Acid-Promoted Rearrangement of the Metalated Thienyl Rings in Dirhodium(II) Complexes with Thienyl Phosphines as Ligands

Several mono- and bis-cyclometalated compounds have been prepared and characterized from the thermal reaction of dirhodium(II) tetraacetate and tris(2-thienyl)phosphine, P(2-C4H3S)3 (1), in toluene/acetic acid mixtures. In refluxing acetic acid, the mono-cyclometalated compound Rh2(O2CCH3)3[(2-C4H2S)P(2-C4H3S)2] (CH3CO2H)2 (2A) isomerizes to Rh2(O2CCH3)3[(3-C4H2S)P(2-C4H3S)2](CH3CO2H)2 (2B), which results from the selective rearrangement of the metalated ring from a 2-thienyl to a 3-thienyl structure. In the same conditions, the bis-cyclometalated compounds of formula Rh2(O2CCH3)2[(2-C4H2S)P(2-C4H3S)2]2(CH3CO2H)2 and with head-to-tail (3AA) or head-to-head (4AA) configuration of the phosphi…

Cyclometallation reactions in complexes of the type Rh(oq)(CO)(P(o-BrC6F4)Ph2)

Abstract The complex [uRh(oq)Br(P( o -Cu 6 F 4 )Ph 2 )(H 2 O)] 2 is obtained by refluxing a solution of Rh(oq)(CO)(P( o -BrC 6 F 4 )Ph 2 ) (oq = 8-oxyquinolinate) in toluene. The structure of this compound has been determined by X-ray diffraction and refined to R = 0.061 and R w = 0.065 factors. The cell has monoclinic symmetry, space group P 2 1 / n ; a 19.513(2), b 17.049(1), c 16.898(1) A and β 99.69(1)°. The structure consists of two independent Rh(oq)Br(P( o -C 6 F 4 )Ph 2 )H 2 O) units linked by hydrogen bonds between the coordinated water molecules and oq ligands to form a distorted boat (six atom ring of junction between the two units). In each unit the metal atom has a distorted oc…

Synthesis and X-ray Crystallographic Characterization of (μ-(Diphenylphosphino)phenyl-C2,P)palladium Bromide. A Novel Tetranuclear Metalated Compound

The synthesis and crystal structure of a tetranuclear palladium cluster, [Pd(PC)Br]4 (PC) = [P(C6H4)Ph2]-), is described. Cleavage of this cluster with phosphines yields the mononuclear species Pd(PC)Br(P) in the form of cis and trans isomers. An equilibrium between mono- and tetranuclear species is observed for P = PCBr.

Part 2. Synthesis, characterization and X-ray structure of a new enantiomerically pure bis-equatorial dirhodium(II) compound

Abstract The UV irradiation of an acetone solution of Rh2(O2CCF3)4 and the chiral phosphane (1S, 2S, 5R)-(2-hydroxy-5-isopropenyl-2-methyl-cyclohexyl)diphenylphosphane, (+)PPh2(CHR*OH) leads to the formation of two diastereoisomeric bis-equatorial compounds of formula Rh2(μ-O2CCF3)2(η1-O2CCF3)2(η2-(+)PPh2(CHR*OH))2 P(+)2 and M(+)2 in a 1.5:1 ratio, respectively. Both compounds have been separated by standard column chromatography. The characterization of the enantiomer M(+)2 has been accomplished by X-ray crystallography. The molecular structure consists of an Rh2 4+ unit bridged by two trifluoroacetate ligands. The coordination of each metal center is fulfilled by one phosphine acting …

ortho-metallation of P(m-MeC6H4)3 in dirhodium(II) tetraacetate. Molecular structure of Rh2(O2CCH3)2[(m-MeC6H3)P(m-MeC6H4)2]2(HO2CCH3)2·CH3CO2H

Abstract The thermal reaction of Rh2(O2CCH3)4(MeOH)2 and P(m-MeC6H4)3 in a 1:2 molar ratio in acetic acid yielded Rh2(O2CCH3)2[(m-MeC6H3)P(m -MeC6H4)2]2(HO2CCH3)2. Purple monoclinic crystals of this compound and one molecule of acetic acid, space group P21/c, were obtained by evaporation of a solution of the original reaction product in acetic acid/CH2Cl2 mixture. The unit cell parameters are a = 21.346(3), b = 11.909(2), c = 20.071 A, β = 97.98(1)° and Z = 4. The structure consists of a dinuclear rhodium core bridged by cisoid acetate groups and two ortho-metallated phosphine ligands. The ortho-metallation occurs at the least sterically hindered carbon atom which is trans to the methyl sub…

Dirhodium(II) compounds with bridging thienylphosphines: studies on reversible P,C/P,S coordination.

Monocyclometalated compound [Rh(2){(C(8)H(4)S)P(C(8)H(5)S)(2)}(CH(3)CO(2)H)(2)(O(2)CCH(3))(3)] (1 a) and bis-cyclometalated compound [Rh(2){(C(8)H(4)S)P(C(8)H(5)S)(2)}(2)(CH(3)CO(2)H)(2)(O(2)CCH(3))(2)] (2 a) have been isolated from the reaction of dirhodium tetraacetate and tris(2-benzo[b]thienyl)phosphine (2 BTP) using low acidic solutions. By contrast, in pure acetic acid the reaction of Rh(2)(O(2)CCH(3))(4) with 2 BTP and tris(2-thienyl)phosphine (2 TP), followed by replacement of the axial acetate ligands by chlorides, led to [Rh(2){(2-C(8)H(5)S)P(2-C(8)H(5)S)(2)}(2)Cl(2)(O(2)CCH(3))(2)] (3 b) and [Rh(2){(2-C(4)H(3)S)P(C(4)H(3)S)(2)}(2)Cl(2)(O(2)CCH(3))(2)] (5 b), respectively. These n…

ChemInform Abstract: Enantiocontrol in the Intermolecular Cyclopropanation Reaction Catalyzed by Dirhodium(II) Complexes with ortho-Metalated Aryl Phosphine Ligands.

(P) and (M) dirhodium(II) complexes with ortho-metalated aryl phosphines are assessed as chiral catalysts in the enantioselective cyclopropanation of styrenes by ethyl diazoacetate; enantioselectivities up to 91% and up to 87%, respectively, for cis- and trans-2-arylcyclopropanecarboxylates are observed.

Fast orthometalation reactions at a binuclear dirhodium(II) complex. Synthesis, crystal structure and reactivity of Rh2(O2CCH3)3[(C6H4)PPh2]·(HO2CCH3)2

Abstract From the reaction of Rh2(O2CCH3)4(MeOH)2, in hot acetic acid with PPh3 the monometalated intermediate Rh2(O2CCH3)3[(C6H4)PPh2](HO2CCH3)2 has been isolated and characterized by an X-ray study. This compound rapidly reacts with an excess of PPh3 in dichloromethane at room temperature to give Rh2(O2CCH3)2-[(C6H4)PPh2]2(PPh3)2 with a head-to-tail structure. The same procedure at higher temperatures gives a mixture of this compound and another doubly metalated compound with a head-to-head structure.

Dinuclear Rh(II) complexes in styrene hydroformylation. Enhancement of catalytic activity through orthometalation

Three dirhodium(II) compounds including orthometalated PPh3 ligands have been tested as catalytic precursors for the hydroformylation of styrene. The activities obtained and the wide range of selectivities have been compared to the same reaction performed with RhH(CO)(PPh3)3, Rh2(O2CCH3)4 and various amounts of triphenylphosphine.

Electrochemical study of dinuclear ruthenium(II)—arene compounds: Electrogeneration of Ru(II)—Ru(I) species

Abstract The preparation and characterization of Ru(II)—arene compounds [{RuCl2(p-cym)}2(μ-L-L)] where p-cym = p-MeC6H4CHMe2; and L-L = diphenylphosphinomethane (I), 1,1′-bisdiphenylphosphinoferrocene (II), pyrazine (III) and 4,4′-bipyridine (IV), are described. Electrochemical data for these compounds obtained by cyclic voltammetry and coulometry are reported. The electrochemical reduction of compounds I or II yields ruthenium(O) species. However, compounds III or IV containing ligands with delocalized Π orbitals undergo one-electron reduction. The ESR signal detected during the electrolysis of compounds III or IV is consistent with one delocalized electron through the whole dinuclear unit.

eCity: Virtual City Environment for Engineering Problem Based Learning

The main objective of the eCITY project is to design, develop and validate a pedagogical methodology, supported by an online, collaborative, city-development simulation engine (Simcity like) that stimulates the integration and continuous exploitation of Problem-Based Learning (PBL) in engineering and science schools but, at the same time, fostering the interest for these orientations in secondary school students. DOI: http://dx.doi.org/10.4995/HEAd15.2015.447

Orthometallation reaction in dirhodium(II) compounds. Selective formation of doubly-metallated compounds with head-to-head structure

Abstract The reaction of the mono-metallated compound Rh 2 (O 2 CCH 3 ) 3 [(C 6 H 4 )P(CH 3 ) (C 6 H 5 )]·2(HO 2 CCH 3 ) with PPh 3 (1:1 molar ratio) has been studied by 31 P NMR spectroscopy. The reaction yields the doubly-metallated compound Rh 2 (O 2 CCH 3 ) 2 [(C 6 H 4 ) P(CH 3 )(C 6 H 5 )]p(C 6 H 4 )P(C 6 H 5 ) 2 ]·2(HO 2 CCH 3 ) with a head-to-head (H-H) configuration. An intermediate reaction compound, not previously observed, has been spectroscopically detected in solution. Analogous intermediate compounds have been detected using P( p -CH 3 C 6 H 4 ) 3 and P( p -ClC 6 H 4 ) 3 instead of triphenylphosphine.

Orthometallation reactions of rhodium compounds containing orthohaloarylphosphines

The reaction of RhCl3·.3H2O with a 3-molar proportion of P(o-ClC6H4)Ph2, (PCCl) at room temperature gives RhCl(PCCl)2 (1), in high yield. Reaction of [Rh(cot)2Cl]2, (cot = cyclooctene), with PCCl, sol12 molar ratio, also gives compound 1. Refluxing of a solution of 1 in 96% ethanol gives RhCl2(PC)(η2-PCCl), [PC  (C6H4)PPh2] (2). Complex 1 reacts with CO to give RhClCO(PCCl)2 (3). 31P NMR studies reveal that 1 exhibits a fluxional behaviour in solution in the temperature range −50 to 0 °C. The low temperature spectrum is consistent with the formulation RhCl(η2-PCCl)(η1-PCCl). In cyclic voltammetry complex 2 shows two two-electronic reduction processes, at −0.98 and −1.56 V. Electrochemical …

ChemInform Abstract: Synthesis and X-Ray Structure of Metalated Rhodium(II) Catalysts with a Chiral Phospholane.

The reaction of Rh2(O2CR)4 (R = CH3, CF3) with the chiral phosphane (2S,5S)-2,5-dimethyl-1-phenylphospholane (PC*H), results in the formation of two diastereoisomers of Rh2(O2CCR)2(PC*)2, with (P) and (M) configuration. These can easily be isolated by chromatographic methods to obtain enantiomerically pure RhII compounds. Preliminary catalytic studies have shown that they induce moderate asymmetry in the cyclization of 5-aryl-1-diazo-2-pentanones and 1-diazo-5-hexen-2-one. X-ray analysis of the (M) diastereoisomer with formula Rh2(O2CCCH3)2(PC*)2 is reported. The crystallographic parameters are as follows: space group P21212 (orthorhombic) with a = 12.1347(11) A, b = 14.5870(13) A, c = 9.81…

Synthesis, characterization and kinetics of the metallation of the intermediate compound to produce compound · (H2O) from Rh(II) tetraacetate

Abstract Photochemical irradiation of mixtures of [Rh2(μ-O2CCH3)4]·(HOCH3)2 and P(2-(CH3O)C6H4)Ph2 (POMe) in CH2Cl2 solution (1:1 molar ratio) yields quantitatively compound [ Rh 2 (μ- O 2 CCH 3 ) 3 ( O 2 CCH 3 )(η 2 - P (2-( CH 3 O ) C 6 H 4 ) Ph 2 ]·( H 2 O ) (1) containing a POMe acting as a chelating equatorial ( P ) axial ( O ) donor ligand. This compound undergoes intramolecular CH activation reaction at one of the phenyl rings in CHCl3 or CH3COOH/toluene solution at room temperature to form the monometallated compound [ Rh 2 (μ- O 2 CCH 3 ) 3 (μ-( C C 3 H 4 ) P (2-( CH 3 O C 6 H 4 ) Ph )]· ( H 2 O ) ( 2 ). The kinetics of the 1 → bd2 reaction have been studied in acid media (CH3CO…

Synthesis, Molecular Structure, and Reactivity of Rhodium(I) Complexes with Diazoalkanes and Related Substrates as Ligands

A series of (diazoalkane)rhodium(I) compounds of the general composition trans-[RhCl(N2CRR‘)(PiPr3)2] with R = R‘ = Ph, p-C6H4Me, p-C6H4Cl and R = Ph, R‘ = p-C6H4Me, o-C6H4Me, CH3, CH2Ph, CF3 has been prepared from the dimer [RhCl(PiPr3)2]2 (1) and the diazoalkane. This preparative route has also been extended to complexes in which the N2C unit(s) of 1,4-C6H4{C(Ph)N2}2, 9-diazofluorene, 9,10-anthraquinone-9-diazide, and 3-methyl-1,4-naphthoquinone-1-diazide is (are) linked to a 14-electron [RhCl(PiPr3)2] fragment. While C(CO2Et)2N2 behaves as expected and affords upon treatment with 1 the complex trans-[RhCl{N2C(CO2Et)2}(PiPr3)2), CH(CO2Et)N2 reacts with the same starting material to give t…

Synthesis and crystal structure of {Rh2(O2CCH3)4·P(o-CH3OH6H4)Ph2}2. A novel dirhodium(II) monoadduct with intermolecular μ-oxo interactions

Abstract We have investigated the reaction of dirhodium tetraacetate with the phosphine P( o -CH 3 OH 6 H 4 )Ph 2 (P) under different experimental conditions. From these reactions we have been able to isolate the dirhodium tetraacetate phosphine mono-adduct. The crystal structure shows that in the solid state this compound forms a centrosymmetric dimer of the dimer, {Rh 2 (O 2 CCH 3 ) 4 ·P(0-CH 3 OC 6 H 4 )Ph 2 } 2 , in which we oxygen atom from one acetate group in one Rh 2 (O 2 CCH 3 ) 4 ·P unit is axially coordinating one Rh atom on another Rh 2 (O 2 CCH 3 ) 4 · P unit (Rh⋯) 2.347(3) A intermolecular versus Rh⋯O 2.455(3) A intermolecular), and vice versa. The RhRh bond distance is 2.414…

Orthometallation reactions of tris(p-methoxyphenyl)phosphine with dirhodium(II) tetraacetate

Abstract Reactions of dirhodium(II)tetraacetate [Rh2(OAc)4] with tris(p-methoxyphenyl)phosphine (PMP) at 1:1 and 1:2 molar ratios yield, first appropriate adducts: [Rh2(OAc)4P(p-CH3OC6H4)3] (1a) and [Rh2(OAc)4{P(p-CH3OC6H4)3}2] (2a), and then orthometallated [Rh2(OAc)3{μ-(p-CH3OC6H3)P(p-CH3OC6H4)2}(HOAc)2] (1) and [Rh2(OAc)2{μ-(p-CH3OC6H3)P(p-CH3OC6H4)2}2(HOAc)2] (2) complexes, respectively. They have been characterized by spectroscopic methods. The molecular structure of 1 has been determined by the X-ray methods. Crystal data: space group P1, a=11.085(5), b=11.387(5), c=13.900(6) A, α=97.29(3), β=105.23(3), γ=91.93(3)°. In this compound The Rh–Rh distance is 2.421(1), Rh–P bond length 2.1…

Photo-assisted formation of a chelating diphos ligand from PPh3 and a cyclometallated [P(C6H4)(C6H5)2]− ligand. Crystal structure of Pd{η2-o-[P(C6H5)2]2(C6H4)}Br2

Abstract The cyclometallated palladium compound, Pd[η2-(C6H4)P(C6H5)2]Br[P(C6H5)3] (1), in the solid state by action of light, evolves to give Pd{η2-o-[P(C6H5)2]2(C6H4)}Br2 (2). This compound contains the diphosphine, o-[P(C6H5)2]2(C6H4), as chelated ligand that is formed by a couple reaction of the metallated ligand η2-[(C6H4)P(C6H5)2]− and the coordinated arylphosphine. A study by NMR spectroscopy confirms that the o-phenylene bridge in the diphosphine ligand in 2 comes from the metallated phosphine ligand in 1.

Electrochemical study on a tricyclic 1,1,1-tricar-bonyl-2,3-1 diazaferrole derivative. II. Activation of carbon monoxide replacement by electron transfer processes

Etudes, par voltammetrie cyclique, de la reduction electrochimique du complexe de diazaferratricyclodecene, en presence de P(OMe) 3

Synthesis and reactivity of the novel hydride derivative RhHCl(TIMP3) (HTIMP3 = tris[1-(diphenylphosphino)-3-methyl-1H-indol-2-yl]methane)

The reaction of HTIMP(3) (HTIMP(3) = tris[1-(diphenylphosphino)-3-methyl-1H-indol-2-yl]methane) with [RhCl(COD)](2) and Rh(acac)(CO)(2) produces RhHCl(TIMP(3)) (1H) and Rh(TIMP(3))(CO) (2), respectively, both exhibiting tetradentate kappaC,kappa(3)P-coordination of the TIMP(3) moiety. The reaction of RhHCl(TIMP(3)) with nucleophiles (L) in the presence of AgBF(4) or AgPF(6) produces different compounds depending on the nature of L. Indeed, cationic Lewis adducts of formula [RhH(L)(TIMP(3))](+) ((2H+)-(5H+)) are obtained when L is CO, CNCH(2)Ph, pyridine or CH(2)CHCN. On the other hand, when the incoming nucleophile is CH(3)COOH the hydride-free complex [Rh(CH(3)COO)(TIMP(3))](+) ((6+)) is o…

ChemInform Abstract: Dinuclear Rh(II) Complexes in Styrene Hydroformylation. Enhancement of Catalytic Activity Through Orthometalation.

Three dirhodium(II) compounds including orthometalated PPh3 ligands have been tested as catalytic precursors for the hydroformylation of styrene. The activities obtained and the wide range of selectivities have been compared to the same reaction performed with RhH(CO)(PPh3)3, Rh2(O2CCH3)4 and various amounts of triphenylphosphine.

C—br insertion reactions in rhodium and iridium compounds containing an ortho-halo-arylphosphine. X-ray structures of two ortho-metallated compounds of formula IrX2[P(C6F4)Ph2][P(o-BrC6F4)Ph2], (X = Cl, Br)

Abstract A comparative study of the reaction of rh and ir complexes with the ortho-bromo-arylphosphine PCBr [PCBr = P(o-BrC6F4)(C6H5)2], is presented. Various PCBr complexes of Ir(I) and Rh(I) undergo rapid insertion of the metal atom into a CBr bond provided the phosphine is coordinated in a η2-mode (Pbr). If the Br coordination is substituted by a superior ligand such as CO or an olefin, no reaction occurs under normal conditions. PCBr complexes of the tervalent metals require a two-electron reduction step prior to the ortho-metallation reaction. Most intermediates were characterized by chemical and spectroscopic analysis. Two intermediates of general formula IrX2(η2-PC)(η-PCBr), [PC = …

High Enantiocontrol in the Intramolecular Cyclopropanation of Diazo Ketones Catalyzed by Dirhodium(II) Complexes with Ortho-Metalated Aryl Phosphine Ligands

[reaction: see text]. Chiral dirhodium(II) complexes, Rh2(O2CCF3)2(PC)2, [PCH = (p-CH3C6H4)3P, (m-CH3C6H4)3P], provide an excellent yield and a high enantiocontrol in the cyclopropanation of alpha-diazo ketones with gamma and delta double bonds. The ee values are significantly dependent on the solvent used; the best results are obtained using pentane.

Ligand Effects on the Chemoselectivity of Ortho-Metalated Rhodium(II) Catalyzed α-Diazo Ketone Transformations

Rh2(OOCR)2(PC)2 complexes (PC = orthometalated phosphines, OOCR = carboxylates) with very polarizable ligands, such as aromatic rings directly joined to the rhodium atoms, control chemoselectivity in competitive metal carbene transformations of α-diazo ketones. These catalysts have a mixed set of ligands that allows choosing among a big selection of ligands to gradually affect the electronic and steric properties of the catalyst. Their selectivity depends on the electrophilicity of the ligands and the polarizability of the metalated aromatic rings. Thus, Rh2(OOCR)2(PC)2 compounds [PC = (C6H4)P(CH3)(C6H5), (p-CH3C6H3)P(p-CH3C6H4)2, (C6H4)P(C6H5)2; R = C3F7 or CF3] exhibit an exceptional sele…

Molecular structure of the compound [Rh2(O2CCH3)3{(C6H4)P(BrC6H4-1,2)(C6H5)} · (HO2CCH3)2].Kinetic study of the exchange reaction of acetate groups with CD3CO2D

Abstract The compound [Rh 2 (O 2 CCH 3 ) 3 {(C 6 H 4 )P(BrC 6 H 4 -1,2) (C 6 H 5 )} · (HO 2 CCH 3 ) 2 ] has been isolated in high yield from the thermal reaction of dirhodium tetraacetate and the phosphine P(BrC 6 H 4 -1,2) (C 6 H 5 ) 2 in acetic acid. The structure of this compound has been determined by X-ray diffraction; it crystallizes in the P 1 (triclinic) space group and contains three acetate groups bridging a Rh 2 4+ unit the RhRh distance being 2.432(1)A; the fourth bridging ligand is an ortho -bromophenyldiphenylphosphine metallated at one of the ortho positions of the unsubstituted phenyl rings. Two molecules of acetic acid occupy the axial coordination positions. Stepwise exch…

Novel unsymmetrical ortho-metalated dirhodium (II) catalysts: trans influence of the axial ligand

Inductive effects of an X axial group which are transmitted through the RhRh bond influence the reactivity of ortho-metalated dirhodium complexes 3 in the cyclization of 1-diazo-5-penten-2-one (4).

Orthometalation reactions in trifluoroacetate dirhodium(II) compounds. Molecular structure of Rh2(O2CCF3)2[(C6H4)PPh2]2·(PPh3)2·2(C7H8)

Abstract Rh 2 (O 2 CCF 3 ) 3 [(C 6 H 4 )PPh 2 ]·(HO 2 CCF 3 ) 2 reacts with PPh 3 yielding the doubly metalated compound Rh 2 (O 2 CCH 3 ) 2− [(C 6 H 4 )PPh 2 ] 2 ·(HO 2 CCF 3 ) 2 . The reaction proceeds via a reactive intermediate with an equatorial phosphine, Rh 2 (η 2 -O 2 CCF 3 )(μ-O 2 CCF 3 ) 2 [(C 6 H 4 )PPh 2 ](PPh 3 )·(HO 2 CCF 3 ), which can also be generated in moderate yield under photochemical conditions. The structure of the PPh 3 bis-adduct Rh 2 (O 2 CCF 3 ) 2 [(C 6 H 4 )PPh 2 ] 2 ·(PPh 3 ) 2 ·2(C 7 H 8 ) has been determined by X-ray diffraction. M r =1663.27, orthorhombic, space group Fdd 2, a =41.748(9), b =21.620(5), c =17.375(5) A, V =15683(6) A 3 , Z =8, D x =1.41 g cm −3…

NMR studies on [Rh(η6-arene)(P(OPH)3)2]ClO4 in the presence of acetone-d6. Arene dissociation and dynamic behaviour of the solvent complex

Abstract Dissociation of the complexes [Rh(η 6 -arene)L 2 ]ClO 4 (arene = mesitylene (Ia), toluene (Ib) and benzene (Ic); L = P(OPh) 3 ) with loss of the arene ligand in CD 2 Cl 2 / acetone- d 6 (95/5 mol/mol) has been studied by 31 P NMR spectroscopy; for initial 0.025 M concentrations of degrees of dissociation were 0.23, 0.33 and 0.85, respectively. The dissociations were first-order, with half-lifes of 31 (Ia), 1.2 (Ib) and 0.7 (Ic) h. The solvent complex [Rh(acetone) m L 2 ]ClO 4 produced by these dissociation reactions showed unusual dynamic structural behaviour. In dry acetone the two phosphorus nuclei were magnetically equivalent (species II-A 2 ), whereas in acetone solutions conta…

Cyclometallation reactions in complexes of the type Rh(oq)(CO)(P(o-BrC6F4)Ph2)

Abstract The reaction of Rh(oq)(CO)(PCBr) (PCBr = P(o-BrC6F4)Ph2; oq = 8-oxyquinolinte)_ in refluxing toluene in the presence of Et4NBr (1/4 molar ratio) gives Rh(oq)Br(PC) (H2O), PC = P (o-C6F4)Ph2, in practically quantitative yield. The water molecule is readily displaced by various P-donor ligands to give complexes of general formula Rh(oq)Br(PC) PR3 (PR3 = PPh3, P(p-MeC6H4)3, P(p-MeOC6H4)3, P(p-FC6H4)3, P(PMe)3 and P(OPh3). The molecular structure of the compound Rh(oq)Br(PC) (PPh3) has been determined by X-ray methods. Crystals of the title compound are monoclinic, space group P21/n with unit cell dimensions a 11.273(4), b 20.087(8), c 17.471(7) A and β 102.15(8)°. The final R for 2304…

Reaction of Rh2(μ2-O2CCH3)3[μ2-(C6H4)PMePh](HO2CCH3)2 with triphenylphosphine: rearrangement of the metalated PMePh2 ligand and formation of a compound with a diphenylphosphinomethanide group in (P,C) coordination; crystal structure of [Rh2(μ2-O2CCH3)2{μ2-(CH2)PPh2}- {μ2-(C6H4)PPh2}(PPh3)]·2CH2Cl2

The reaction of [Rh2(μ2-O2CCH3)3{μ2-(C6H4)PMePh}] (1) in CHCl3 with one mole of PPh3 gives the two phosphine monoadducts, which are in rapid equilibrium above −40 °C. After 6 h at room temperature this mixture gives [Rh2(μ2-O2CCH32{μ2-(C6H4)PMePh}{μ2-(C6H4)PPh2}](HO2CCH3)2 (3), a doubly metalated compound with a head-to-head configuration. 1 reacts with two moles of PPh3, forming the bis-adduct 1.P2, which at 10 °C gives a mixture 3, in the form of its phosphine adduct 3.P, and [Rh2(μ2-O2CCH3)2{μ2-(CH2)PPh2}{μ2- (C6H4) PPh2}(PPh3)] (2). It is confirmed that 3.P is not the kinetic product in the reaction from 1.P2 to 2. The structure of [Rh2(μ2-O2CCH3)2{μ2-(CH2)PPh2}{μ2-(CP6H4) PPh2} (PPh3)]…

Five coordinate complexes of the type Rh(SnCl3)(NBD)L2

Several new rhodium complexes of general formulation Rh(SnCl3)(NBD)L2 (L=P(OMe)3, P(OMe)2Ph, P(OMe)Ph2, P(OEt)3, P(OEt)2Ph, P(OEt)Ph2, P(O-i-Pr)3, P(OPh)3) have been prepared and characterized by elemental analysis and by i.r. and n.m.r. spectroscopy. The complexes show low or no conductivity in acetone solution and react with carbon monoxide (1 atm).

Rhodium (II) compounds with functionalized metalated phosphines as bridging ligands

Abstract The reaction of Rh2(O2CCH3)4 · 2CH3OH with the phosphine P(4-BrC6H4)2(C6H5), 2, results in the formation of the monometalated compound Rh2(O2CCH3)3[PC] · 2CH3CO2H (PC representing a metalated P(4-BrC6H4)2(C6H5)). The reaction involves selective metalation of the phosphine at one Br-substituted ring (12:1 isomer ratio). The reaction of Rh2(O2CCH3)3[(4-BrC6H3)P(4-BrC6H4)(C6H5)] · 2CH3CO2H, 4, with one additional mol of triphenylphosphine yields a mixture of two main stereoisomers Rh2(O2CCH3)2[(4-BrC6H3)P(4-BrC6H4)(C6H5)] [(C6H4)P(C6H5)2] · 2CH3CO2H, 5a and 5b, that were isolated as pure compounds. These two compounds were resolved in the corresponding M and P enantiomers as trifluoro…

ChemInform Abstract: Reactivity and Selectivity of ortho-Metalated Rhodium(II) Complexes in C-H Insertion Reactions of α-Diazo Compounds.

Regioselective intramolecular C−H insertion reactions of α-diazo β-keto esters and α-diazo ketones are mediated by Rh2[OOCR]4-x[PC]x (x = 1, 2; PC = ortho-metalated phosphine; R = CH3, C3F7). In particular, the intramolecular transformation of 1-diazo-5-methyl-3-propyl-2-hexanone catalyzed by Rh2[OOCCH3]2[PC]2 (PC = (C6H4)P(C6H5)2, head-to-tail (H−T) configuration) afforded only the tertiary C−H insertion product. By comparison, no C−H insertion reaction was promoted by doubly metalated complexes with a head-to-head (H−H) configuration. Rh2[OOCR]3[PC] compounds were found to be less suited for these type of reactions.

Synthesis of Dirhodium(II) Complexes with Several Cyclometalated Thienylphosphines

The thermal reaction of dirhodium tetraacetate with tris(3-thienyl)phosphine (3TP), diphenyl(3-thienyl)phosphine (3TPPh2), and diphenyl(2-thienyl)phosphine (2TPPh2) gives rise to mono-cyclometalated and bis-cyclometalated compounds; the latter can have a head-to-head (H−H) or head-to-tail (H−T) configuration. Bis-cyclometalated compounds with H−T configuration can be prepared in high yield under photochemical conditions or by combining irradiation with subsequent thermal treatment in acetic acid. The reactivity order of aromatic ring C−H activation is phenyl < 2-thienyl ≪ 3-thienyl, which leads to a selective activation of the thienyl ring. Thus, only one mono-cyclometalated compound is obt…

Multifaceted Palladium Catalysts Towards the Tandem Diboration-Arylation Reactions of Alkenes

Novel Pd(2) (6+) compounds have been synthesized in high yield. These compounds and their Pd(2) (4+) counterparts as synthetic precursors mediate the diboration of vinylarenes and aliphatic 1-alkenes, and under mild and basic reaction conditions they produce a variety of 1,2-diboronate esters with excellent conversions and chemoselectivities. The presence of bis(catecholato)diboron (B(2)cat(2)) favours the reduction of Pd(III) to Pd(II), while the catalytic precursor of Pd(II) is transformed into Pd(0)-nanoparticles. An "in situ" catalytic tandem reaction has been designed to transform the diboronate intermediates into the monoarylated product, which after oxidative workup, provides the car…

Electrochemical studies on organometallic compounds—xx. Electrogeneration of an unusual organometallic derivative of ruthenium(I)

Abstract The two-electron reduction of dinuclear ruthenium complexes [RuCl 2 (η 6 - p -cymene)] 2 ( p -cymene = p -CH 3 C 6 H 4 CH(CH 3 ) 2 ] give the corresponding relatively stable ruthenium(I) dimer derivative. The same species can also be obtained by electrochemical reduction of the cationic complexes [(η 6 - p -cymene)Ru(μ-Cl) 3 Ru(η 6 - p -cymene)]PF 6 . A redox mechanism is proposed.

Enantiocontrol in the intermolecular cyclopropanation reaction catalyzed by dirhodium(II) complexes with ortho-metalated aryl phosphine ligands

(P) and (M) dirhodium(II) complexes with ortho-metalated aryl phosphines are assessed as chiral catalysts in the enantioselective cyclopropanation of styrenes by ethyl diazoacetate; enantioselectivities up to 91% and up to 87%, respectively, for cis- and trans-2-arylcyclopropanecarboxylates are observed. Barberis, Mario, Mario.Barberis@uv.es ; Lahuerta Peña, Pascual, Pascual.lahuerta@uv.es ; Perez Prieto, Julia, Julia.Perez@uv.es ; Sanau Torrecilla, Mercedes, Mercedes.Sanau@uv.es

Enantio- and diastereocontrol in intermolecular cyclopropanation reaction of styrene catalyzed by dirhodium(II) complexes with bulky ortho-metalated aryl phosphines

Enantiomerically pure dirhodium(II) complexes with ortho-metalated p-substituted aryl phosphines have been shown to be enantio- and diastereoselective in the cyclopropanation of styrene by ethyl diazoacetate. Enantioselectivities up to 91% and diastereoselectivities up to 90% are observed for ethyl cis-2-phenylcyclopropanecarboxylate. Estevan Estevan, Francisco, Francisco.Estevan@uv.es ; Lahuerta Peña, Pascual, Pascual.lahuerta@uv.es ; Lloret Fillol, Julio, Julio.Lloret@uv.es ; Sanau Torrecilla, Mercedes, Mercedes.Sanau@uv.es ; Ubeda Picot, M Angeles, Angeles.Ubeda@uv.es ; Vila Gomez, Jaume Llorenc, Jaume.Vila@uv.es

Reactivity and Selectivity of Ortho-Metalated Rhodium(II) Complexes in C−H Insertion Reactions of α-Diazo Compounds

Regioselective intramolecular C−H insertion reactions of α-diazo β-keto esters and α-diazo ketones are mediated by Rh2[OOCR]4-x[PC]x (x = 1, 2; PC = ortho-metalated phosphine; R = CH3, C3F7). In particular, the intramolecular transformation of 1-diazo-5-methyl-3-propyl-2-hexanone catalyzed by Rh2[OOCCH3]2[PC]2 (PC = (C6H4)P(C6H5)2, head-to-tail (H−T) configuration) afforded only the tertiary C−H insertion product. By comparison, no C−H insertion reaction was promoted by doubly metalated complexes with a head-to-head (H−H) configuration. Rh2[OOCR]3[PC] compounds were found to be less suited for these type of reactions.

Synthesis, Reactivity, and X-ray Crystallographic Characterization of Mono-, Di-, and Tetranuclear Palladium(II)-Metalated Species

The reactivity of the tetranuclear metallated palladium compound (Pd[mu 2-(C6H4)PPh2]Br)4 (1) with different ligands has been investigated with the aim of evaluating the influence of the entering ligand on the nature of the reaction products. The results confirmed the ability of the ligand [(C6H4)PPh2]- to expand a bridging [mu 2-] or a chelating [eta 2-] coordination mode, depending on the auxiliary ligands present in the complex. Bulky phosphines stabilize mononuclear species of formula (Pd[eta 2-(C6H4)PPh2]Br[P]), with a four-atom metallocycle, while small phosphines give dinuclear compounds. The molecular structures of three different metalated palladium compounds have been determined b…

New Dinuclear Catalysts Rh2(N−O)2[(C6H4)P(C6H5)2]2 with Imidate Ligands:  Synthesis and Isomerization from Head-to-Tail to Head-to-Head Configuration of the Imidate Ligands

Two new dirhodium(II) catalysts of general formula Rh(2)(N-O)(2)[(C(6)H(4))P(C(6)H(5))(2)](2) (N-O = C(4)H(4)NO(2)) are prepared, starting from Rh(2)(O(2)CCH(3))(2)(PC)(2)L(2) [PC = (C(6)H(4))P(C(6)H(5))(2) (head-to-tail arrangement); L = HO(2)CCH(3)]. The thermal reaction of Rh(2)(O(2)CCH(3))(2)(PC)(2).L(2) with the neutral succinimide stereoselectively gives one compound that according to the X-ray structure determination has the formula Rh(2)(C(4)H(4)NO(2))(2)[(C(6)H(4))P(C(6)H(5))(2)](2) (1). It corresponds to the polar isomer with two bridging imidate ligands in a head-to-head configuration. However, stepwise reaction of Rh(2)(O(2)CCH(3))(2)(PC)(2).L(2) with (CH(3))(3)SiCl and potassiu…

Reaction of Tris(2-thienyl)phosphine with Dirhodium(II) Acetate. Orthometalation of a Heteroaromatic π-System and an Unusual Ring Rearrangement

The reaction of tris (2-thienyl)phosphine (1) with dirhodium(II) acetate in a 9:1 refluxing toluene/ acetic acid mixture for 2 h leads to the formation of two metalated compounds. The structure of one of them contained two new orthometalated phosphines in a head-to-head arrangement, and, surprisingly, the metalated thiophene rings, but not the nonmetalated ones, were rearranged to a 3-thienyl structure. Both types of dirhodium compounds were assessed in a catalytic α-diazo ester transformation.

Orthometalation of Tris(3-sodium sulfonatophenyl)phosphine with Dirhodium(II) Acetate

Tetraacetatodirhodium(II) reacts with tris(3-sodium sulfonatophenyl)phosphine (TPPTS) giving [Rh2(μ-OOCCH3)3{μ-(3-NaO3SC6H3)P(C6H4SO3Na-3)2}(HOOCCH3)]·6H2O (1) and [Rh2(μ-OOCCH3)2{μ-(3-NaO3SC6H3)P(C6H4SO3Na-3)2}2(HOOCCH3)]·12H2O (2). Their structures and properties have been studied by electronic, IR, and 31P{1H}, 1H, 1H{31P}, and 13C{1H} NMR spectroscopies. In compound 1, one of the acetate bridges is replaced by a phosphine ligand, orthometalated via the C2 carbon atom of the phenyl ring. One axial site of the Rh24+ core is occupied by a sulfonato group of the metalated ring and another one by a labile molecule of acetic acid. 1H NMR spectroscopy shows that chemical shifts of the aromatic…

Determination of equilibrium constants and computational interaction energies for adducts of [Rh2(RCO2)(4-n)(PC)n] (n = 0-2) with Lewis bases.

Properties of dirhodium catalysts with cyclometalated aryl phosphine ligands have been studied. We report here the study of the acid−base reaction of Rh2(RCO2)2(PC)2(H2O)2 catalysts (PC = cyclometalated aryl phosphine) with different Lewis bases. The determination of the equilibrium constants of these reactions can be used to study to which extent the properties of the axial coordination site of the catalyst, considered the active site, are affected by modification of the metalated phosphines, the carboxylate ligands, or the incoming axial ligand. The trends in the computational density functional theory interaction energies show good agreement with the major trends in the equilibrium const…

Cyclometallation reactions in complexes of the type Rh(oq)(CO)[P(o-BrC6F4)Ph2]. The molecular structure of F4)Ph2] (oq = 8-hydroxyquinolinate)

Cyclometallation occurs when a solution of the complex Rh(oq)(CO)(PCBr), (PCBr = 2-bromo-3,4,5,6-tetrafluorophenyldiphenylphosphine; oq = 8-hydroxyquinolinate) in toluene is refluxed, giving Rh(oq)2(PC) (PC = P(C6F4)(C6H5)2) and a dimeric compound, not yet completely characterized, formulated as Rh2Br(oq)(PCBr)2. Rh(oq)2(PC) was characterized by elemental analysis, by conductance measurements, and by 19F, 31P NMR and infrared spectroscopy. Its molecular structure was determined by single-crystal X-ray methods and refined by standard procedures to final agreement factors R and Rw of 0.067 and 0.060 for 5346 observed data. Lattice constants are 15.8494(6), 14.7188(5), 14.6675(5) A and β 96.93…

Reactions of rhodium trifluoroacetate with triphenylphosphine and pyridine. Molecular structure of Rh2(O2CCF3)4(py)4

Abstract Rh 2 (O 2 CCF 3 ) 4 reacts with two mol of triphenylphosphine forming the adduct Rh 2 (O 2 CCF 3 ) 4 (PPh 3 ) 2 . This compound in solution, even at room temperature, undergoes slow stepwise orthometalation of the phosphine ligands forming the doubly metalated compound Rh 2 (O 2 CCF 3 ) 2 [(C 6 H 4 )P(C 6 H 5 ) 2 ] 2 . This reaction has been monitored by 31 P NMR spectroscopy detecting in solution three reaction intermediates. Rh 2 (O 2 CCF 3 ) 4 reacts with excess of pyridine to form the compound Rh 2 (O 2 CCF 3 ) 4 (py) 4 that can be structurally classified as a class III adduct. It contains two bridging and two monodentate equatorial carboxylates and two equatorial and two axial…

Synthesis of Cyclometalated Rhodium(III) Complexes. Study of the Carbonyl Insertion Reactions into the Rh-C Bond of the Metalocycle

Abstract In this paper we report the preparation of new orthometalated rhodium(III) compounds of the formula Rh(oq)(AB)(PC), from Rh(oq)(Br)(PC)(H20), AB being a bidentade anionic ligand, oq= 8-oxyquinolate and PC = P(o-C6F4)Ph2. Their redox behaviour is also described. The reaction of Rh(Oq)(Br)(PC)(H20) [Oq = 5-Me-8-oxyquinolate (5-Meoq), 8-oxyquinolate] with carbon monoxide under pressure leads to expansion of the metalocycle ring by CO insertion into the Rh-C bond.

Electrochemical study on (NN)Fe3 (CO)9 ((NN) = 2,3-diazanorbornene) and related compounds. A new example of activation of carbon monoxide replacement by electron transfer.

Abstract The compound (NN)Fe 3 (CO) 9 ( 1 ) in tetrahydrofuran undergoes two reversible one-electron reduction processes in cyclic voltammetry at the platinum electrode. A rapid electron transfer-catalyzed reaction occurs when 1 is reduced in the presence of L (L = P(OMe) 3 ) and this gives (NN)Fe 3 (CO) 8 L ( 2 ), quantitatively. Only an electron-induced nucleophilic substitution is observed for compound 2 under the same conditions, yielding (NN)Fe 3 (CO) 7 L 2 , which undergoes a similar reaction but with much lower efficiency, to give (NN)Fe 3 (CO) 6 L 3 .

Preparation and Oxidative Addition Reactions of 8-Oxyquinolate Rhodium(I) Complexes

Abstract The preparation of new 8-oxyquinolate rhodium(I) complexes of the general formula Rh(Oq) (L) (L') is described. They undergo oxidative addition reactions with halogens and methyl iodide to give the corresponding rhodium(III) complexes. NMR measurements are used in the characterization of the compounds.

Selective ortho-metallation reaction of the phosphine P(o-ClC6H4)Ph2. Synthesis and crystal structure of [Rh2(μ-O2CCH3)3(μ-(ClC6H3)PPh2(OH2)2]·CHCl3

Abstract From the reaction of [Rh2(O2CCH3)4(MeOH)2] in hot acetic acid with P(o-ClC6H4)Ph2, two monometallated compounds [Rh2(O2CCH3)3(C6H4)P(o-ClC6H4)Ph(HO2CCH3)2] (1), already described, and [Rh2(O2CCH3)3{(ClC6H3)PPh2}(OH2)2] have been isolated. The new compound has been characterized by an X-ray study. It crystallizes in the triclinic space group P1. It contains three acetate groups bridging a Rh24+ unit that has a Rh-Rh bond distance of 2.426(1) A; the fourth bridging ligand is derived from one P(o-ClC6H4)Ph2 metallated in the halogenated ring. The two water molecules occupy the axial coordination sites.

Heterogeneous Dinuclear Rhodium(II) Hydroformylation Catalysts—Performance Evaluation and Silsesquioxane-Based Chemical Modeling

Supported, air stable, and reusable hydroformylation catalysts have been prepared by immobilizing dinuclear rhodium(II) complexes bearing ortho-metalated arylphosphane ligands on amorphous silica and mesoporous MCM-41 supports by phosphane tethers. The oligosilsesquioxane model complex of the catalytic site 1 has been prepared analogously and characterized by single-crystal X-ray diffraction analysis.

Isolation of enantiomerically pure organometallic palladium compounds: synthesis of the triangles prepared from enantiopure [cis-Pd2(C6H4PPh2)2(NCCH3)4]2+

Reaction of the racemic [Pd(C(6)H(4)PPh(2))Br](4) () with the silver salt of 1R-(1alpha,2beta,3alpha)]-3-methyl-2-(nitromethyl)-5-oxocyclopentaneacetate, (R)-AgO(2)CR*, results in the formation of a mixture of diastereoisomers (RRR)- and (SRR)- of the formula Pd(2)(C(6)H(4)PPh(2))(2)(O(2)CR*)(2) that were separated by standard chromatographic methods. Each diastereoisomer was readily converted into the tetrametallic stereoisomers (SS)- and (RR)-, of the formula [Pd(C(6)H(4)PPh(2))Br](4) that were isolated and characterized by X-ray crystallography. The R enantiomer of the solvated cationic species [cis-Pd(2)(C(6)H(4)PPh(2))(2)(NCCH(3))(4)](2+), obtained from (RR)-, was reacted with ammonium…

Photochemical ligand rearrangement in dirhodium(II) compounds. Structure of Rh2(O2CCH3)2(η2-O2CCH3)[(C6H4)PPh2] (η2-PCCl)(PCClP-ClC6H4)Ph2

Abstract The photochemical reaction of the adducts Rh2(O2CCH3)3[(C6H4)P(o-ClC6H4)Ph]· (P(p-XC6H4)3) (X=H, Me, Cl), yield the compounds Rh2(O2CCH3)2(η2-O2CCH3)[(p-XC6H3)P (p-XC6H4)2](η2-PCCl), (PCCl=P(o-ClC6H4)Ph2) in a ligand rearrangement reaction that involves activation of CH and RhC bonds. The factors that favour this process are studied by carrying out photochemical reactions with different phosphines. The structures of Rh2(O2CCH3)2(η2-O2CCH3) [(C6H4)PPh2](η2-PCCl) has been determined by X-ray diffraction. Mr=1321.1, orthorhombic, space group Pbcn, a=20.339(8), b=20.07(6), c=23.07(3) A , V=9413(3) A 3 , Z=8, D x =1.86 g cm −3 . Mo Kα radiation (graphite crystal monochromator, λ=0.071…

The structure of a dinuclear silver(I) complex: Ag2[S2C2(CN)2] [P(C6H5)3]4

Abstract The crystal structure of the dimeric Ag maleonitriledithiolate complex, Ag2[S2C2(CN)2] [P(C6- H5)3]4 (1), has been performed. Complex 1 crystallizes in the space group P21/c with a = 12.2898(77), b = 23.8325(91), c = 23.1790(118) A, β = 101.315(43)° and Z = 4. Refinement using 3253 reflections with Fo2>3σ(Fo2) yielded R = 0.0662, Rw= 0.0669. The most interesting aspect of the structure is the strong bridging interaction of the chelating maleonitriledithiolate ligand with the second Ag center, where a Ag-S distance of 2.478 A is observed. The residual bonding capability of the sulfur atoms in the chelating anion [Ag(S2C2(CN)2)(PPh3)2]− for [Ag(PPh3)2]+ is demonstrated.

Diastereospecific control in the synthesis of enantiomerically pure bis-equatorial rhodium(II) catalysts by chiral phosphanes

The reaction of Rh2(O2CR)4 [R = CH3, CF3] with the chiral phosphane (1S,2S,5R)-(2-hydroxy-5-isopropenyl-2-methylcyclohexyl)(diphenyl)phosphane, (+)PPh2(CH−R*−OH) or its enantiomer (1R,2R,5S)-(2-hydroxy-5-isopropenyl-2-methylcyclohexyl)(diphenyl)phosphane, (−)-PPh2(CH−R*−OH), results in the specific formation of the products (P)-Rh2(μ-O2CR)2(η1-O2CR)2{η2-(+)PPh2(CH−R*−OH)}2 [P(+)1, R = CH3; P(+)2 R = CF3] and (M)-Rh2(μ-O2CR)2(η1-O2CR)2{η2-(−)-PPh2(CH−R*−OH)}2 [M(−)1, R = CH3; M(−)2, R = CF3] in a high yield. Their synthesis, characterisation and catalytic behaviour in metal−carbenoid reactions are reported. X-ray analysis of P(+)2 and M(−)2 shows, in each case, a Rh24+ unit supported by two …

Synthesis, Structure, and Reactivity of the First Enantiomerically Pure Ortho-Metalated Rhodium(II) Dimer

Dinuclear palladium(ii) compounds with bridging cyclometalated phosphines. Synthesis, crystal structure and electrochemical study

The structural characterization of bis-cyclometalated palladium(II) compounds of formula Pd2[(micro-(C6X4)PPh2]2(micro-O2CR)2 [X = H, R = CH3 (3), CF3 (4), C(CH3)3 (5) and C6F5 (6); X = F, R = CH3 (7) and CF3 (8)], has confirmed its paddle wheel structure with two palladium atoms bridged by two acetates and two metalated phosphines in a head-to-tail arrangement. The Pd...Pd distances are in the range 2.6779(16)-2.7229(8) A. Under cyclic voltammetric conditions, compounds 3-6, in CH2Cl2 solution, were found to undergo a reversible oxidation peak in the range of potential values 0.84-1.25 V. A second partially-reversible oxidation is observed at more positive potentials (1.37-1.55 V). For com…

ChemInform Abstract: Multifaceted Palladium Catalysts Towards the Tandem Diboration-Arylation Reactions of Alkenes.

Novel Pd(2) (6+) compounds have been synthesized in high yield. These compounds and their Pd(2) (4+) counterparts as synthetic precursors mediate the diboration of vinylarenes and aliphatic 1-alkenes, and under mild and basic reaction conditions they produce a variety of 1,2-diboronate esters with excellent conversions and chemoselectivities. The presence of bis(catecholato)diboron (B(2)cat(2)) favours the reduction of Pd(III) to Pd(II), while the catalytic precursor of Pd(II) is transformed into Pd(0)-nanoparticles. An "in situ" catalytic tandem reaction has been designed to transform the diboronate intermediates into the monoarylated product, which after oxidative workup, provides the car…

Synthesis of orthometallated rhodium(III) compounds. Crystal structures of [RhCl2{η2(C6H4)PPh2}(η2-dppm)] and [RhCl{η2(C6H4)PPh2}(η1-PCCl)(phen)] (SbF6)·CH2Cl2 (dppm=bis(diphenylphosphino)methane; PCCl=P(o-ClC6H4)Ph2; phen=1,10 phenanthroline)

Abstract Neutral and cationic rhodium(III) metallated compounds containing a four-membered ring are prepared by different synthetic methods: (i) from rhodium(I) compounds that contain the ligand P( o -ClC 6 H 4 )PPh 2 , by 2c-2e intramolecular oxidative addition; (ii) from metallated dirhodium(II) compounds; (iii) by ligand substitution in [RhCl 2 {η 2 -(C 6 H 4 )PPh 2 }{η 2 -P( o -ClC 6 H 4 )Ph 2 }]. The crystal structures of [RhCl 2 {η 2 -(C 6 H 4 )PPh 2 }(η 2 -dppm)] ( 2 ) and of the dichloromethane solvate of [RhCl{η 2 -(C 6 H 4 )PPh 2 }{η 1 -P( o -ClC 6 H 4 )Ph 2 }(phen)](SbF 6 ) ( 11 ) have been determined by X-ray diffraction methods. In both complexes the Rh atom is in the distorted…

High Yield Syntheses of Stable, Singly Bonded Pd26+ Compounds

A general method for the syntheses of dipalladium compounds having a singly bonded Pd26+ core and the formula R,S-cis-Pd2(C6H4PPh2)2(O2CR)2Cl2 is described. When the alkyl group in the carboxylate ligands is an electron donating group, the compounds are stable and the yields high. The Pd-Pd distances for the diamagnetic compounds with R = CF3 and CMe3 are 2.5434(4) and 2.5241(9) A, respectively. Calculations at the DFT level suggest that the electronic configuration is sigma2pi4delta2delta*2pi*4. These represent rare examples of palladium(III) compounds.

Synthesis of new orthometallated iridium(III) compounds by chemical and electrochemical methods

Abstract Replacement of one phosphine ligand in IrCl 3 (η 2 -PCBr)(η 1 -PCBr) ( 1 ) (PCBr = P( o -BrC 6 F 4 )Ph 2 ), by various P-donor ligands has given compounds of stoichiometry IrCl 3 (η 2 -PCBr)L ( 3 : L = PMePh 2 ; 4 : L = P( p -MeC 6 H 4 ) 3 ; 5 : L = P(OMe) 3 , 6 : L = P(OPh) 3 ). All of these show two irreversible reduction peaks in the range −1.1, −1.3 and ca. −2.0 V. The electrochemical reduction of compound 1 at −1.5 V (at 0°C) leads to a very reactive iridium(I) species, probably IrCl(PCBr) 2 , which undergoes intramolecular orthometallation at room temperature. Three compounds are obtained as the results of this chemical conversion: IrBr 2 (PC)(PCBr) ( 7 ), IrCl 2 (PC)(PCBr) (…

Reactions of dirhodium(II) monometallated compounds with phosphines. Factors affecting the reactivity and the structure of the doubly-metallated compounds. Molecular structure of Rh2(O2CCH3)2[(C6H4)P(C6H5)2][(p-ClC6H3)P(p-ClC6H4)2] · (HO2CCH3)2·(C6H6), a compound with two different metallated phosphines

Abstract Monometallated compounds of formula Rh2(O2CCH3)3[(p-XC6H3)P(p-XC6H4)2](HO2CCH3)2 (X=CH3, Cl) have been prepared in good yield. The reactions with p-substituted triarylphosphines P(p-X′C6H4)3 (X′=CH3, H, Cl) have been studied. For X=X′ and [P]/[Rh2]=1 all the resulting doubly metallated compounds Rh2(O2CCH3)2[(p- XC6H3)P(p-XC6H4)2](HO2CCH3)2 (X=CH3, Cl) have head-to-tail (H-T) structure. For [P]/[Rh2]=3 reaction progress is observed at room temperature. When X=X′ a 1:1 mixture of H-T and H-H compounds is formed for X=Cl but only the H-H compound is obtained for X=CH3. For X ≠ X′ mixtures of H-T and H-H compounds are obtained. The entering phosphine, and to a less extent the phosphin…

A dinuclear rhodium(III) complex with the N,N′-ethylenebis(salicylideneiminato) (salen) ligand in a bridging bis-bidentate mode of coordination. Crystal structure of [{Rh(η2-(C6H4)PPh2)(η2-P(o-ClC6H4)Ph2)}2(salen)](SbF6)2

In this communication we describe the synthesis and crystal structure of the complex [{Rh(η 2 -(C 6 H 4 )PPh 2 )(η 2 -P(o-ClC 6 H 4 )Ph 2 )} 2 (salen)]-(SbF 6 ) 2 , showing the bridging configuration of the salen ligand

Simultaneous substitution of bridging acetate groups and reversible RhC bond cleavage in [Rh2(O2CCH3)3-{(C6H4)PPh2}(HO2CCH3)2] in the presence of CF3CO2H. Crystal structure of [Rh2(O2CCF3)3-{(C6H4)PPh2}(HO2CCF3)2]

Abstract The reaction of the monometallated compound [Rh2(O2CCH3)3 {(C6H4)PPh2}(HO2CCH3)2] (1) with CF3CO2H at room temperature yields [Rh2(O2CCF3)3{(C6H4)PPh2}(HO2CCF3)2] (3) as the only isolable product. Compound 3 has been characterized by X-ray methods. 3 crystallizes in the space group P21 / n. It contains three trifluoroacetate groups bridging a Rh4+2 unit with a RhRh bond distance of 2.438(1) Ă; the fourth bridging ligand is a triphenylphosphine metallated at one of the ortho positions. Two molecules of trifluoroacetic acid occupy the axial coordination positions. In addition to the substitution of acetate groups, reversible electrophilic RhC bond activation is observed.

AC3-Symmetric Palladium Catalyst with a Phosphorus-Based Tripodal Ligand

An Unprecedented Iridium(III) Catalyst for Stereoselective Dimerisation of Terminal Alkynes

A novel iridium(III) hydride complex, IrHCl(TIMP 3 ) {HTIMP 3 = tris[1-(diphenylphosphino)-3-methyl-lH-indol-2-yl]methane) was prepared and fully characterized in both the solid state and in solution. Chloride abstraction by silver cations provides a more reactive compound, [IrH-(TIMP 3 )][BF 4 ], which can react with pyridine (py) and phenylacetylene to yield the complexes [IrH-(TIMP 3 )(py)][BF 4 ] and [Ir(PhCH=C-CH=CHPh)-(TIMP 3 )][BF 4 ], respectively. Interestingly, IrH-(TIMP 3 )(py)][BF 4 ] efficiently catalyses the stereoselective dimerisation of model terminal alkynes to the 1,4-disubstituted (E)-but-1-en-3-yne only.

Dinuclear Ortho-Metalated Palladium(II) Compounds with N,N- and N,O-Donor Bridging Ligands. Synthesis of New Palladium(III) Complexes

New dinuclear ortho-metalated palladium(II) compounds with N,N′-diarylformamidinates, Pd2[(C6H4)PPh2]2[R′NC(H)NR′]2 (R′ = C6H5, 3a; R′ = p-CH3C6H4, 3b; R′ = p-CH3OC6H4, 3c) and N,O-donor ligands, Pd2[(C6H4)PPh2]2[N,O]2 (N,O = succinimidate (5), phtalimidate (6), 2-hydroxypyridinate (7), acetanilidate (8)) have been synthesized and characterized by NMR spectroscopy and X-ray diffraction methods. The oxidation with iodobenzene dichloride gave new and rare Pd26+ compounds, Pd2[(C6H4)PPh2]2[R′NC(H)NR′]2Cl2 (R′ = C6H5, 4a; R′ = p-CH3C6H4, 4b). DFT calculations on the Pd24+ → Pd26+ oxidation reaction show that the substituents on the amidinate N atoms have a greater effect on the reaction energy …

Preparation and study of silver maleonitriledithiolate complexes

Abstract This paper reports the reaction of Ag2(mnt) and [(NEt4)Ag(mnt)] (mnt2− = maleonitriledithiolate) with PPh3 and 1,2-bis(diphenylphosph

Synthesis and X-ray structure of metalated Rhodium(II) catalysts with a chiral phospholane

The reaction of Rh2(O2CR)4 (R = CH3, CF3) with the chiral phosphane (2S,5S)-2,5-dimethyl-1-phenylphospholane (PC*H), results in the formation of two diastereoisomers of Rh2(O2CCR)2(PC*)2, with (P) and (M) configuration. These can easily be isolated by chromatographic methods to obtain enantiomerically pure RhII compounds. Preliminary catalytic studies have shown that they induce moderate asymmetry in the cyclization of 5-aryl-1-diazo-2-pentanones and 1-diazo-5-hexen-2-one. X-ray analysis of the (M) diastereoisomer with formula Rh2(O2CCCH3)2(PC*)2 is reported. The crystallographic parameters are as follows: space group P21212 (orthorhombic) with a = 12.1347(11) A, b = 14.5870(13) A, c = 9.81…

ChemInform Abstract: Novel Unsymmetrical ortho-Metalated Dirhodium(II) Catalysts: trans Influence of the Axial Ligand.

Inductive effects of an X axial group which are transmitted through the RhRh bond influence the reactivity of ortho-metalated dirhodium complexes 3 in the cyclization of 1-diazo-5-penten-2-one (4).

A Highly Regio-, Diastereo- and Enantioselective Intramolecular Cyclopropanation Reaction of a Racemic α-Diazo Ketone Catalyzed by Chiral ortho-Metalated Dirhodium(II) Compounds.

Abstract A series of racemic dirhodium(II) compounds with two ortho-metalated aryl phosphine ligands in a head-to-tail arrangement Rh2(O2CR)2(pc)2 (pc=ortho-metalated aryl phosphine) (1a–k) were tested in the regio- and stereoselective cyclopropanation of racemic 1-diazo-6-methyl-3-(2-propenyl)-5-hepten-2-one 2, which possesses two different reactive CC double bonds for a five-membered-ring formation. The complexes Rh2(O2CCH3)2(pc)2 {pc=[(C6H4)P(C6H5)2], [(p-CH3C6H3)P(p-CH3C6H4)2], and [(C6H4)P(C6H5)(C6F5)]} (1a–d) successfully enhanced the cyclopropanation of trisubstituted versus monosubstituted CC bonds to give an 80:20 selectivity ratio. The reaction occurred with excellent diastereos…