Electronic Structures and Molecular Properties of Chalcogen Nitrides Se2N2 and SeSN2

2006

The electronic structures and molecular properties of S2N2 as well as the currently unknown chalcogen nitrides Se2N2 and SeSN2 have been studied using various ab initio and density functional methods. All molecules share a qualitatively similar electronic structure and can be primarily described as 2π-electron aromatics having minor singlet diradical character of 6−8% that can be attributed solely to the nitrogen atoms. This diradical character is manifested in the prediction of their molecular properties, in which coupled cluster and multiconfigurational approaches, as well as density functional methods, show the best performance. The conventional ab initio methods RHF and MP2 completely f…

Computational investigations of 18-electron triatomic sulfur–nitrogen anions

2018

MRCI-SD/def2-QZVP and PBE0/def2-QZVP calculations have been employed for the analysis of geometries, stabilities, and bonding of isomers of the 18-electron anions N2S2−, NS2−, and NSO−. Isomers of the isoelectronic neutral molecules SO2, S2O, S3, and O3 are included for comparison. The sulfur-centered acyclic NSN2−, NSS−, and NSO− anions are the most stable isomers of their respective molecular compositions. However, the nitrogen-centered isomers SNS− and SNO− lie close enough in energy to their more stable counterparts to allow their occurrence. The experimental structural information, where available, is in good agreement with the optimized bond parameters. The bonding in all investigate…

Homoleptic, heteroleptic and mixed-valent thallium and indium complexes of multidentate chalcogen-centred PCP-bridged ligands.

2011

The metathetical reaction of [Li(TMEDA)][HC(PPh(2)Se)(2)] ([Li(TMEDA)]1) with TlOEt in a 1:1 molar ratio afforded a homoleptic Tl(I) complex as an adduct with LiOEt, Tl[HC(PPh(2)Se)(2)]·LiOEt (7), which undergoes selenium-proton exchange upon mild heating (60 °C) to give the mixed-valent Tl(I)/Tl(III) complex {[Tl][Tl{(Se)C(PPh(2)Se)(2)}(2)]}(∞) (8). Treatment of TlOEt with [Li(TMEDA)](2)[(SPh(2)P)(2)CE'E'C(PPh(2)S)(2)] (3b, E' = S; 3c, E' = Se) in a 2:1 molar ratio produced the binuclear Tl(i)/Tl(i) complexes Tl(2)[(SPh(2)P)(2)CE'E'C(PPh(2)S)(2)] (9b, E' = S; 9c, E' = Se), respectively. Selenium-proton exchange also occurred upon addition of [Li(TMEDA)]1 to InCl(3) to yield the heterolepti…

Acyclic imidoselenium(ii) dihalides: synthesis and X-ray structures of ClSe[N(But)Se]nCl (n = 1, 2)

2000

The reaction of SeCl2 with tert-butylamine in THF yields the acyclic imidoselenium(II) dichlorides ClSeN(But)NSeCl and ClSeN(But)SeN(But)SeCl, in addition to the six-membered ring Se3(NBut)3.

Experimental and Theoretical Investigations of Structural Trends for Selenium(IV) Imides and Oxides: X-ray Structure of Se3(NAd) 2

2004

The thermal decomposition of Se(NAd)(2) (Ad = 1-adamantyl) in THF was monitored by (77)Se NMR and shown to give the novel cyclic selenium imide Se(3)(NAd)(2) as one of the products. An X-ray structural determination showed that Se(3)(NAd)(2) is a puckered five-membered ring with d(Se-Se) = 2.404(1) A and |d(Se-N)| = 1.873(4) A. On the basis of (77)Se NMR data, other decomposition products include the six-membered ring Se(3)(NAd)(3), and the four-membered rings AdNSe(micro-NAd)(2)SeO and OSe(micro-NAd)(2)SeO. The energies for the cyclodimerization of E(NR)(2) and RNEO (E = S, Se; R = H, Me, (t)Bu, SiMe(3)), and the cycloaddition reactions of RNSeO with E(NR)(2), RNSO(2) with Se(NR)(2), and S…

Structural and Spectroscopic Studies of the PCP-Bridged Heavy Chalcogen-Centered Monoanions [HC(PPh2E)(PPh2)]− (E = Se, Te) and [HC(PR2E)2]− (E = Se,…

2009

Selenium- and tellurium-containing bis(diphenylphosphinoyl)methane monoanions were prepared by oxidation of the anion [HC(PPh2)2]− with elemental chalcogens. The selenium-containing isopropyl derivative was synthesized by generating [H2C(PiPr2)2] via a reaction between [H2C(PCl2)2] and 4 equiv of iPrMgCl prior to in situ oxidation with selenium followed by deprotonation with LiNiPr2. The solid-state structures of the lithium salts of the monochalcogeno anions TMEDA·Li[HC(PPh2E)(PPh2)] (E = Se (Li7a), E = Te (Li7b)) and the dichalcogeno anions TMEDA·Li[HC(PR2Se)2] (R = Ph (Li8a), iPr (Li8c)) revealed five- and six-membered LiEPCP and LiSePCPSe rings, respectively. The homoleptic group 12 com…

Conformations and Energetics of Sulfur and Selenium Diimides

2003

The geometries and energetics of different conformations of sulfur and selenium diimides E(NR) 2 (E = S, Se; R = H, Me, 'Bu, C 6 H 3 Me 2 -2,6, SiMe 3 ) have been studied by using various ab initio and DFT molecular orbital techniques. The syn,syn conformation is found to be most stable for parent E(NH) 2 , but in general, the preferred molecular conformation for substituted chalcogen diimides is syn,anti. In the case of E(NH) 2 the present calculations further confirm that syn,syn and syn,anti conformations lie energetically close to each other. From the three different theoretical methods used, B3PW91/6.31G * proved to be the most suitable method for predicting the geometries of chalcogen…

Synthesis, Spectroscopic, and Structural Investigation of the Cyclic [N(PR2E)2]+ Cations (E = Se, Te; R = iPr, Ph):  the Effect of Anion and R-Group …

2006

Two-electron oxidation of the [N(PiPr2E)2]- anion with iodine produces the cyclic [N(PiPr2E)2]+ (E =Se, Te) cations, which exhibit long E-E bonds in the iodide salts [N(PiPr2Se)2]I (4) and [N(PiPr2Te)2]I (5). The iodide salts 4 and 5 are converted to the ion-separated salts [N(PiPr2Se)2]SbF6 (6) and [N(PiPr2Te)2]SbF6 (7) upon treatment with AgSbF6. Compounds 4-7 were characterized in solution by multinuclear NMR, vibrational, and UV-visible spectroscopy supported by DFT calculations. A structural comparison of salts 4-7 and [N(PiPr2Te)2]Cl (8) confirms that the long E-E bonds in 4, 5, and 8 can be attributed primarily to the donation of electron density from a lone pair of the halide counte…

Electrochemical and Electronic Structure Investigations of the [S3N3]• Radical and Kinetic Modeling of the [S4N4]n/[S3N3]n (n = 0, −1) Interconversion

2009

Voltammetric studies of S4N4 employing both cyclic (CV) and rotating disk (RDE) methods in CH2Cl2 at a glassy carbon electrode reveal a one-electron reduction at −1.00 V (versus ferrocene/ferrocenium), which produces a second redox couple at −0.33 V, confirmed to be the electrochemically generated [S3N3]− by CV studies on its salts. Diffusion coefficients (CH2Cl2/0.4 M [nBu4N][PF6]) estimated by RDE methods: S4N4, 1.17 × 10−5 cm2 s−1; [S3N3]−, 4.00 × 10−6 cm2 s−1. Digital simulations of the CVs detected slow rates of electron transfer for both couples and allowed for a determination of rate constants for homogeneous chemical reaction steps subsequent to electron transfer. The common paramet…

Bonding Trends in Lewis Acid Adducts of S4N4 — X-Ray Structure of TeCl4×S4N4.

2006

Tetrasulfur tetranitride and tellurium tetrachloride react in dichloromethane to form a 1:1 adduct TeCl4·S4N4 (1). The crystal structure of 1 shows that TeCl4 is bonded to the S4N4 ring through a Te–N linkage. As a consequence, the transannular S···S bonds in S4N4 are broken and the molecule assumes an open, monocyclic conformation. The Te–N bond of 2.16(1) A is slightly longer than the single bond. The S–N bonds span a range of 1.55(1)–1.67(1) A. The adduct 1 was also characterized by mass spectrometry and Raman spectroscopy. The bonding and spectroscopic properties of 1 are compared by DFT calculations at the B3PW91/(RLC ECP) level of theory with those of BF3·S4N4 (2), SO3·S4N4 (3), AsF5·…

Syntheses, X-ray structures, and redox behaviour of the group 14 bis-boraamidinates M[PhB(μ-N-t-Bu)2]2 (M = Ge, Sn) and Li2M[PhB(μ-N-t-Bu)2]2 (M = Sn…

2009

The solid-state structures of the complexes M[PhB(μ-N-t-Bu)2]2 (1a, M= Ge; 1b, M = Sn) were determined to be spirocyclic with two orthogonal boraamidinate (bam) ligands N,N′-chelated to the group 14 centre. Oxidation of 1b with SO2Cl2 afforded the thermally unstable, blue radical cation {Sn[PhB(μ-N-t-Bu)2]2}•+, identified by electron paramagnetic resonance (EPR) spectroscopy supported by density functional theory (DFT) calculations, whereas the germanium analogue 1a was inert towards SO2Cl2. The reaction between Li2[PhB(μ-N-t-Bu)2]2 and SnCl2 or PbI2 in 2:1 molar ratio in diethyl ether produced the novel heterotrimetallic complexes Li2Sn[PhB(μ-N-t-Bu)2]2 (2b) and (Et2O·Li)LiPb[PhB(μ-N-t-Bu…

Synthesis of a labile sulfur-centred ligand, [S(H)C(PPh2S)2]−: structural diversity in lithium(i), zinc(ii) and nickel(ii) complexes

2016

A high-yield synthesis of [Li{S(H)C(PPh2S)2}]2 [Li2·(3)2] was developed and this reagent was used in metathesis with ZnCl2 and NiCl2 to produce homoleptic complexes 4 and 5b in 85 and 93% yields, respectively. The solid-state structure of the octahedral complex [Zn{S(H)C(PPh2S)2}2] (4) reveals notable inequivalence between the Zn-S(C) and Zn-S(P) contacts (2.274(1) Å vs. 2.842(1) and 2.884(1) Å, respectively). Two structural isomers of the homoleptic complex [Ni{S(H)C(PPh2S)2}2] were isolated after prolonged crystallization processes. The octahedral green Ni(ii) isomer 5a exhibits the two monoprotonated ligands bonded in a tridentate (S,S',S'') mode to the Ni(ii) centre with three distinctl…

The cyclic [N(PiPr2E)2]+ (E = Se, Te) cations: a new class of inorganic ring system.

2006

The two-electron oxidation of [(tmeda)NaN(PiPr2E)2] with iodine produces the cyclic [N(PiPr2E)2]+ (E = Se, Te) cations, which exhibit long E–E bonds in the iodide salts. peerReviewed

Experimental and theoretical investigations of the redox behavior of the heterodichalcogenido ligands [(EP(i)Pr2)(TeP(i)Pr2)N](-) (E = S, Se): cyclic…

2008

The two-electron oxidation of the lithium salts of the heterodichalcogenidoimidodiphosphinate anions [(EP (i)Pr 2)(TeP (i)Pr 2)N] (-) ( 1a, E = S; 1b, E = Se) with iodine yields cyclic cations [(EP (i)Pr 2)(TeP (i)Pr 2)N] (+) as their iodide salts [(SP (i)Pr 2)(TeP (i)Pr 2)N]I ( 2a) and [(SeP (i)Pr 2)(TeP (i)Pr 2)N]I ( 2b). The five-membered rings in 2a and 2b both display an elongated E-Te bond as a consequence of an interaction between tellurium and the iodide anion. One-electron reduction of 2a and 2b with cobaltocene produces the neutral dimers (EP (i)Pr 2NP (i)Pr 2Te-) 2 ( 3a, E = S; 3b, E = Se), which are connected exclusively through a Te-Te bond. Two-electron reduction of 2a and 2b …

Structures and EPR spectra of binary sulfur–nitrogen radicals from DFT calculations

2007

Abstract The scattered electron paramagnetic resonance (EPR) spectroscopic data for binary sulfur–nitrogen (S,N) radicals have been compiled and critically assessed.Many of these are inorganic rings or cages.For each species, possible equilibrium structures in the gas phase and the EPR hyperfine coupling (hfc) constants have been calculated with DFT using the B3LYP functional and basis sets of triple-ζ (or better) quality.Good agreement is obtained between calculated and measured values for the well characterized [S3N2]+ , a planar π-radical for which the s-component of the orbitals is likely to be reasonably independent of minor geometrical changes between gas-phase and condensed-phase sta…

Synthesis and Redox Behaviour of the Chalcogenocarbonyl Dianions, [(E)C(PPh2S)2]2−: Formation and Structures of Chalcogen−Chalcogen Bonded Dimers and…

2010

The lithium salts of the chalcogenocarbonyl dianions [(E)C(PPh(2)S)(2)](2-) (E=S (4 b), Se (4 c)) were produced through the reactions between Li(2)[C(PPh(2)S)(2)] and elemental chalcogens in the presence of tetramethylethylenediamine (TMEDA). The solid-state structure of {[Li(TMEDA)](2)[(Se)C(PPh(2)S)(2)]}-[{Li(TMEDA)}(2)4 c]-was shown to be bicyclic with the Li(+) cations bis-S,Se-chelated by the dianionic ligand. One-electron oxidation of the dianions 4 b and 4 c with iodine afforded the diamagnetic complexes {[Li(TMEDA)](2)[(SPh(2)P)(2)CEEC(PPh(2)S)(2)]} ([Li(TMEDA)](2)7 b (E=S), [Li(TMEDA)](2)7 c (E=Se)), which are formally dimers of the radical anions [(E)C(PPh(2)S)(2)](-) (.) (E=S (5 …

Bonding Trends in Lewis Acid Adducts of S 4 N 4 – X‐ray Structure of TeCl 4 ·S 4 N 4

2006

Tetrasulfur tetranitride and tellurium tetrachloride react in dichloromethane to form a 1:1 adduct TeCl4·S4N4 (1). The crystal structure of 1 shows that TeCl4 is bonded to the S4N4 ring through a Te–N linkage. As a consequence, the transannular S···S bonds in S4N4 are broken and the molecule assumes an open, monocyclic conformation. The Te–N bond of 2.16(1) A is slightly longer than the single bond. The S–N bonds span a range of 1.55(1)–1.67(1) A. The adduct 1 was also characterized by mass spectrometry and Raman spectroscopy. The bonding and spectroscopic properties of 1 are compared by DFT calculations at the B3PW91/(RLC ECP) level of theory with those of BF3·S4N4 (2), SO3·S4N4 (3), AsF5·…

Preparation and structural characterization of (Me(3)SiNSN)(2)Se, a new synthon for sulfur-selenium nitrides.

2002

The reaction of (Me(3)SiN)(2)S with SeCl(2) (2:1 ratio) in CH(2)Cl(2) at -70 degrees C provides a route to the novel mixed selenium-sulfur-nitrogen compound (Me(3)SiNSN)(2)Se (1). Crystals of 1 are monoclinic and belong the space group P2(1)/c, with a = 7.236(1) A, b = 19.260(4) A, c = 11.436(2) A, beta = 92.05(3) degrees, V = 1592.7(5) A(3), Z = 4, and T = -155(2) degrees C. The NSNSeNSN chain in 1 consists of Se-N single bonds (1.844(3) A) and S=N double bonds (1.521(3)-1.548(3) A) with syn and anti geometry at the N=S=N units. The N-Se-N bond angle is 91.8(1) degrees. The EI mass spectrum shows a molecular ion with good agreement between the observed and calculated isotopic distributions…

The Nature of Transannular Interactions in E4N4 and E82+ (E = S, Se)

2015

The electronic structures of tetrachalcogen tetranitrides, E4N4, and octachalcogen dications, E8(2+), and the nature of their intramolecular E···E interactions (E = S, Se) was studied with high-level theoretical methods. The results reveal that the singlet ground states of both systems have a surprisingly large correlation contribution which functions to weaken and therefore lengthen the cross-ring E-E bond. The observed correlation effects are primarily static in E4N4, whereas in E8(2+) the dynamic part largely governs the total correlation contribution. The presented description of bonding is the first that gives an all-inclusive picture of the origin of cross-ring interactions in E4N4 an…

PCP-bridged chalcogen-centred anions: coordination chemistry and carbon-based reactivity.

2012

Since the discovery of the stabilising influence of thiophosphinoyl groups in methanediides by Le Floch et al. (Angew. Chem. Int. Ed., 2004, 43, 6382), numerous transition metal, lanthanide and actinide complexes of bis(thiophosphinoyl) carbene ligands have been investigated with an emphasis on the electronic structure and reactivity of the metal–carbon bonds. This Perspective begins by discussing main group (s- and p-block) complexes of this ligand and draws attention to differences compared to their d and f-block analogues. Investigations targeting the heavy chalcogen analogues of the Le Floch ligand have revealed an unusual carbon-based reactivity that led to the discovery of novel multi…

Experimental and theoretical investigations of the contact ion pairs formed by reactions of the anions [(EPR2)2N]- (R = (i)Pr, (t)Bu; E = S, Se) with…

2010

Reactions of the sodium salts [(EPR(2))(2)N]Na(TMEDA) (R = (i)Pr, (t)Bu; E = S, Se) with the iodide salts [(TePR(2))(2)N]I (R = (i)Pr, (t)Bu) in toluene produce the mixed-chalcogen systems [(EPR(2))(2)N][(TePR(2))(2)N] (6b, E = Se, R = (t)Bu; 6c, E = S, R = (t)Bu; 7b, E = Se, R = (i)Pr; 7c, E = S, R = (i)Pr). Compounds 6b, 6c, 7b, and 7c have been characterized in solution by variable-temperature multinuclear ((31)P, (77)Se, and (125)Te) NMR spectroscopy and in the solid state by single-crystal X-ray crystallography. The structures are comprised of contact ion pairs linked by bonds between Te and S or Se atoms. For the tert-butyl derivatives 6b and 6c, the anionic half of the molecule is co…

Formation, Structural Characterization, and Calculated NMR Chemical Shifts of Selenium-Nitrogen Compounds from SeCl4 and ArNHLi (Ar = supermesityl, m…

2004

Supermesityl selenium diimide [Se{N(C6H2tBu3-2, 4, 6)}2; Se{N(mes*)}2] can be prepared in a good yield from the reaction of SeCl4 and (mes*)NHLi. The molecule adopts an unprecedented anti, anti-conformation, as deduced by DFT calculations at PBE0/TZVP level of theory and supported by 77Se NMR spectroscopy and a crystal structure determination. An analogous reaction involving (C6H2Me3-2, 4, 6)NHLi [(mes)NHLi] unexpectedly lead to the reduction of selenium and afforded the selenium diamide Se{NH(mes)}2 that was characterized by X-ray crystallography and 77Se NMR spectroscopy. The Se-N bonds of 1.847(3) and 1.852(3) A show normal single bond lengths. The <NSeN bond angle of 109.9(1)° also indi…

Computational modeling of isotropic electron paramagnetic resonance spectra of doublet state main group radicals

2007

The combined use of theoretical and mathematical methods in the analysis of electron paramagnetic resonance data has greatly increased the ability to interpret even the most complex spectra reported for doublet state inorganic main group radicals. This personal account summarizes the theoretical basis of such an approach and provides an in-depth discussion of some recent illustrative examples of the utilization of this methodology in practical applications. The emphasis is on displaying the enormous potential embodied within the approach. peerReviewed

Experimental and theoretical investigations of structural isomers of dichalcogenoimidodiphosphinate dimers: dichalcogenides or spirocyclic contact io…

2007

A synthetic protocol for the tert-butyl-substituted dichalcogenoimidodiphosphinates [Na(tmeda){(EPtBu(2))(2)N}] (3 a, E=S; 3 b, E=Se; 3 c, E=Te) has been developed. The one-electron oxidation of the sodium complexes [Na(tmeda){(EPR(2))(2)N}] with iodine produces a series of neutral dimers (EPR(2)NPR(2)E--)(2) (4 b, E=Se, R=iPr; 4 c, E=Te, R=iPr; 5 a, E=S, R=tBu; 5 b, E=Se, R=tBu; 5 c, E=Te, R=tBu). Attempts to prepare 4 a (E=S, R=iPr) in a similar manner produced a mixture including HN(SPiPr(2)). Compounds 4 b, 4 c and 5 a-c were characterised by multinuclear NMR spectra and by X-ray crystallography, which revealed two alternative structures for these dimeric molecules. The derivatives 4 b,…

Bond stretching and redox behavior in coinage metal complexes of the dichalcogenide dianions [(SPh2P)2CEEC(PPh2S)2]2- (E=S, Se): diradical character …

2011

The metathetical reactions of a) [Li(tmeda)](2)[(S)C(PPh(2)S)(2)] (Li(2)·3c) with CuCl(2) and b) [Li(tmeda)](2)[(SPh(2)P)(2)CSSC(PPh(2)S)(2)] (Li(2)·4c) with two equivalents of CuCl both afford the binuclear Cu(I) complex {Cu(2)[(SPh(2)P)(2)CSSC(PPh(2)S)(2)]} (5c). The elongated (C)S-S(C) bond (ca. 2.54 and 2.72 A) of the dianionic ligand observed in the solid-state structure of 5c indicate the presence of diradical character as supported by theoretical analyses. The treatment of [Li(tmeda)](2)[(SPh(2)P)(2)CSeSeC(PPh(2)S)(2)] (Li(2)·4b) and Li(2)·4c with AgOSO(2)CF(3) produce the analogous Ag(I) derivatives, {Ag(2)[(SPh(2)P)(2)CEEC(PPh(2)S)(2)]} (6b, E=Se; 6c, E=S), respectively. The disele…

Selenium Imides:  77Se NMR Investigations of the SeCl2−tBuNH2 Reaction and X-ray Structures of Se3(NtBu)3, tBuNSe(μ-NtBu)2SO2, and tBuNSe(μ-NtBu)2SeO

2000

The reaction of SeCl2 with tert-butylamine in various molar ratios in THF at −78 °C has been investigated by 77Se NMR spectroscopy. In addition to the known Se−N heterocycles Se6(NtBu)2 (1) and Se9(NtBu)6 (2), the acyclic imidoselenium(II) dichlorides ClSe[N(tBu)Se]nCl (4, n = 1; 5, n = 2) and two new cyclic selenium imides [Se3(NtBu)2]n (3, n = 1 or 2) and Se3(NtBu)3 (6) have been isolated and identified. An X-ray analysis shows that 6 is a six-membered ring in a chair conformation with |d(Se−N)| = 1.833 A. Crystal data:  6, trigonal, P3c1, a = 9.8660(3) A, c = 20.8427(7) A, V = 1757.0(1) A3, Z = 6. The 1H, 13C, and 77Se NMR data for 1−6 are reported, and some reassignments of earlier lite…

New Insights into the Chemistry of Imidodiphosphinates from Investigations of Tellurium-Centered Systems

2010

Dichalcogenido-imidodiphosphinates, [N(PR(2)E)(2)](-) (R = alkyl, aryl), are chelating ligands that readily form cyclic complexes with main group metals, transition metals, lanthanides, and actinides. Since their discovery in the early 1960s, researchers have studied the structural chemistry of the resulting metal complexes (where E = O, S, Se) extensively and identified a variety of potential applications, including as NMR shift reagents, luminescent complexes in photonic devices, or single-source precursors for metal sulfides or selenides. In 2002, a suitable synthesis of the tellurium analogs [N(PR(2)Te)(2)](-) was developed. In this Account, we describe comprehensive investigations of t…

A Selenium-Nitrogen Chain with Selenium in Different Oxidation States

2017

ChemInform Abstract: Preparation and Structural Characterization of (Me3SiNSN)2Se, a New Synthon for Sulfur-Selenium Nitrides.

2010

The reaction of (Me(3)SiN)(2)S with SeCl(2) (2:1 ratio) in CH(2)Cl(2) at -70 degrees C provides a route to the novel mixed selenium-sulfur-nitrogen compound (Me(3)SiNSN)(2)Se (1). Crystals of 1 are monoclinic and belong the space group P2(1)/c, with a = 7.236(1) A, b = 19.260(4) A, c = 11.436(2) A, beta = 92.05(3) degrees, V = 1592.7(5) A(3), Z = 4, and T = -155(2) degrees C. The NSNSeNSN chain in 1 consists of Se-N single bonds (1.844(3) A) and S=N double bonds (1.521(3)-1.548(3) A) with syn and anti geometry at the N=S=N units. The N-Se-N bond angle is 91.8(1) degrees. The EI mass spectrum shows a molecular ion with good agreement between the observed and calculated isotopic distributions…

Syntheses and Structures of Magnesium and Zinc Boraamidinates: EPR and DFT Investigations of Li, Mg, Zn, B, and In Complexes of the [PhB(NtBu)2]•- An…

2006

The first magnesium and zinc boraamidinate (bam) complexes have been synthesized via metathetical reactions between dilithio bams and Grignard reagents or MCl2 (M = Mg, Zn). The following new classes of bam complexes have been structurally characterized:  heterobimetallic spirocycles {(L)μ-Li[PhB(μ-NtBu)2]}2M (6a,b, M = Mg, L = Et2O, THF; 6c, M = Zn, L = Et2O); bis(organomagnesium) complexes {[PhB(μ3-NtBu)2](MgtBu)2(μ3-Cl)Li(OEt2)3} (8) and {[PhB(μ3-NtBu)2](MgR)2(THF)2} (9a, R = iPr; 9b, R = Ph); mononuclear complex {[PhB(μ-NDipp)2]Mg(OEt2)2} (10). Oxidation of 6a or 6c with iodine produces persistent pink (16a, M = Mg) or purple (16b, M = Zn) neutral radicals {Lx-μ-Li[PhB(μ-NtBu)2]2M}• (L …

An Unusual Ditelluride: Synthesis and Molecular and Electronic Structures of the Dimer of the Tellurium-Centered Radical [TePiPr2NiPr2PTe]•

2005

Facile formation of the ditelluride [(TePiPr2NiPr2PTe-)2], which exists as a centrosymmetric dimer (see picture: Te green, P purple, N blue, C gray) with a weak Te[BOND]Te bond, embodies a new feature of the chemistry of dichalcogenoimidodiphosphinate ligands. The monotelluride HPiPr2NiPr2PTe analogue is obtained as the P[BOND]H tautomer. peerReviewed

Structural and Spectroscopic Studies of the PCP-Bridged Heavy Chalcogen-Centered Monoanions [HC(PPh2E)(PPh2)]− (E = Se, Te) and [HC(PR2E)2]− (E = Se,…

2009

Selenium- and tellurium-containing bis(diphenylphosphinoyl)methane monoanions were prepared by oxidation of the anion [HC(PPh2)2]− with elemental chalcogens. The selenium-containing isopropyl derivative was synthesized by generating [H2C(PiPr2)2] via a reaction between [H2C(PCl2)2] and 4 equiv of iPrMgCl prior to insitu oxidation with selenium followed by deprotonation with LiNiPr2. The solid-state structures of the lithium salts of the monochalcogeno anions TMEDA·Li[HC(PPh2E)(PPh2)] (E = Se (Li7a), E = Te (Li7b)) and the dichalcogeno anions TMEDA·Li[HC(PR2Se)2] (R = Ph (Li8a), iPr (Li8c)) revealed five- and six-membered LiEPCP and LiSePCPSe rings, respectively. The homoleptic group 12 comp…

Synthesis and Structures of Aluminum and Magnesium Complexes of Tetraimidophosphates and Trisamidothiophosphates: EPR and DFT Investigations of the P…

2005

Reactions of (RNH)3PNSiMe3 (3a, R = tBu; 3b, R = Cy) with trimethylaluminum result in the formation of {Me2Al(μ-NtBu)(μ-NSiMe3)P(NHtBu)2]} (4) and the dimeric trisimidometaphosphate {Me2Al[(μ-NCy)(μ-NSiMe3)P(μ-NCy)2P(μ-NCy)(μ-NSiMe3)]AlMe2} (5a), respectively. The reaction of SP(NHtBu)3 (2a) with 1 or 2 equiv of AlMe3 yields {Me2Al[(μ-S)(μ-NtBu)P(NHtBu)2]} (7) and {Me2Al[(μ-S)(μ-NtBu)P(μ-NHtBu)(μ-NtBu)]AlMe2} (8), respectively. Metalation of 4 with nBuLi produces the heterobimetallic species {Me2Al[(μ-NtBu)(μ-NSiMe3)P(μ-NHtBu)(μ-NtBu)]Li(THF)2} (9a) and {[Me2Al][Li]2[P(NtBu)3(NSiMe3)]} (10) sequentially; in THF solutions, solvation of 10 yields an ion pair containing a spirocyclic tetraimid…

New Insights into the Chemistry of Imidodiphosphinates from Investigations of Tellurium-Centered Systems

2010

Dichalcogenido-imidodiphosphinates, [N(PR2E)2]− (R = alkyl, aryl), are chelating ligands that readily form cyclic complexes with main group metals, transition metals, lanthanides, and actinides. Since their discovery in the early 1960s, researchers have studied the structural chemistry of the resulting metal complexes (where E = O, S, Se) extensively and identified a variety of potential applications, including as NMR shift reagents, luminescent complexes in photonic devices, or single-source precursors for metal sulfides or selenides. In 2002, a suitable synthesis of the tellurium analogs [N(PR2Te)2]− was developed. In this Account, we describe comprehensive investigations of the chemistry…

Electrochemical and Electronic Structure Investigations of the [S3N3]• Radical and Kinetic Modeling of the [S4N4]n/[S3N3]n (n = 0, −1) Interconversion

2009

Voltammetric studies of S4N4 employing both cyclic (CV) and rotating disk (RDE) methods in CH2Cl2 at a glassy carbon electrode reveal a one-electron reduction at −1.00 V (versus ferrocene/ferrocenium), which produces a second redox couple at −0.33 V, confirmed to be the electrochemically generated [S3N3]− by CV studies on its salts. Diffusion coefficients (CH2Cl2/0.4 M [nBu4N][PF6]) estimated by RDE methods: S4N4, 1.17 × 10−5 cm2 s−1; [S3N3]−, 4.00 × 10−6 cm2 s−1. Digital simulations of the CVs detected slow rates of electron transfer for both couples and allowed for a determination of rate constants for homogeneous chemical reaction steps subsequent to electron transfer. The common paramet…

Experimental and Theoretical Investigations of the Contact Ion Pairs Formed by Reactions of the Anions [(EPR2)2N]− (R = iPr, tBu; E = S, Se) with the…

2009

Reactions of the sodium salts [(EPR2)2N]Na(TMEDA) (R = iPr, tBu; E = S, Se) with the iodide salts [(TePR2)2N]I (R = iPr, tBu) in toluene produce the mixed-chalcogen systems [(EPR2)2N][(TePR2)2N] (6b, E = Se, R = tBu; 6c, E = S, R = tBu; 7b, E = Se, R = iPr; 7c, E = S, R = iPr). Compounds 6b, 6c, 7b, and 7c have been characterized in solution by variable-temperature multinuclear (31P, 77Se, and 125Te) NMR spectroscopy and in the solid state by single-crystal X-ray crystallography. The structures are comprised of contact ion pairs linked by bonds between Te and S or Se atoms. For the tert-butyl derivatives 6b and 6c, the anionic half of the molecule is coordinated in a bidentate (E,E′) fashio…

Stable spirocyclic neutral radicals: aluminum and gallium boraamidinates

2005

Stable dark red (M = Al) or dark green (M = Ga) neutral radicals {[PhB(μ-NtBu)2]2M}˙ are obtained by the oxidation of their corresponding anions with iodine, and EPR spectra supported by DFT calculations show that the spin density is equally delocalized over all four nitrogen atoms in these spiroconjugated systems. peerReviewed

Synthesis of a labile sulfur-centred ligand, [S(H)C(PPh2S)2]-: structural diversity in lithium(i), zinc(ii) and nickel(ii) complexes

2016

A high-yield synthesis of [Li{S(H)C(PPh2S)2}]2 [Li2·(3)2] was developed and this reagent was used in metathesis with ZnCl2 and NiCl2 to produce homoleptic complexes 4 and 5b in 85 and 93% yields, respectively. The solid-state structure of the octahedral complex [Zn{S(H)C(PPh2S)2}2] (4) reveals notable inequivalence between the Zn–S(C) and Zn–S(P) contacts (2.274(1) Å vs. 2.842(1) and 2.884(1) Å, respectively). Two structural isomers of the homoleptic complex [Ni{S(H)C(PPh2S)2}2] were isolated after prolonged crystallization processes. The octahedral green Ni(II) isomer 5a exhibits the two monoprotonated ligands bonded in a tridentate (S,S′,S′′) mode to the Ni(II) centre with three distinctl…

Experimental and Theoretical Investigations of Structural Trends for Selenium(IV) Imides and Oxides: X-ray Structure of Se3(NAd)2

2004

The thermal decomposition of Se(NAd)2 (Ad = 1-adamantyl) in THF was monitored by 77Se NMR and shown to give the novel cyclic selenium imide Se3(NAd)2 as one of the products. An X-ray structural determination showed that Se3(NAd)2 is a puckered five-membered ring with d(Se−Se) = 2.404(1) Å and |d(Se−N)| = 1.873(4) Å. On the basis of 77Se NMR data, other decomposition products include the six-membered ring Se3(NAd)3, and the four-membered rings AdNSe(μ-NAd)2SeO and OSe(μ-NAd)2SeO. The energies for the cyclodimerization of E(NR)2 and RNEO (E = S, Se; R = H, Me, tBu, SiMe3), and the cycloaddition reactions of RNSeO with E(NR)2, RNSO2 with Se(NR)2, and S(NR)2 with Se(NR)2 have been calculated at…

Cubic and Spirocyclic Radicals Containing a Tetraimidophosphate Dianion [P(NR)3(NR‘)]•2-

2005

The reaction of Cl3PNSiMe3 with 3 equiv of LiHNR (R = iPr, Cy, tBu, Ad) in diethyl ether produces the corresponding tris(amino)(imino)phosphoranes (RNH)3PNSiMe3 (1a, R = iPr; 1b, R = Cy; 1c, R = tBu; 1d, R = Ad); subsequent reactions of 1b−d with nBuLi yield the trilithiated tetraimidophosphates {Li3[P(NR)3(NSiMe3)]} (2a, R = Cy; 2b, R = tBu; 2c, R = Ad). The reaction of [(tBuNH)4P]Cl with 1 equiv of nBuLi results in the isolation of (tBuNH)3PNtBu (1e); treatment of 1e with additional nBuLi generates the symmetrical tetraimidophosphate {Li3[P(NtBu)4]} (2d). Compounds 1 and 2 have been characterized by multinuclear (1H, 13C, and 31P) NMR spectroscopy; X-ray structures of 1b,c were also obtai…

Experimental and Theoretical Investigations of Structural Isomers of Dichalcogenoimidodiphosphinate Dimers: Dichalcogenides or Spirocyclic Contact Io…

2007

A synthetic protocol for the tert-butyl-substituted dichalcogenoimidodiphosphinates [Na(tmeda){(EPtBu2)2N}] (3 a, E=S; 3 b, E=Se; 3 c, E=Te) has been developed. The one-electron oxidation of the sodium complexes [Na(tmeda){(EPR2)2N}] with iodine produces a series of neutral dimers (EPR2NPR2E[BOND])2 (4 b, E=Se, R=iPr; 4 c, E=Te, R=iPr; 5 a, E=S, R=tBu; 5 b, E=Se, R=tBu; 5 c, E=Te, R=tBu). Attempts to prepare 4 a (E=S, R=iPr) in a similar manner produced a mixture including HN(SPiPr2). Compounds 4 b, 4 c and 5 a–c were characterised by multinuclear NMR spectra and by X-ray crystallography, which revealed two alternative structures for these dimeric molecules. The derivatives 4 b, 4 c, 5 a an…

Synthesis, X-ray structures and redox behaviour of the group 14 bis-boraamidinates M[PhB(μ-N-t-Bu)2]2 (M = Ge, Sn) and Li2M[PhB(μ-N-t-Bu)2]2 (M = Sn,…

2009

The solid-state structures of the complexes M[PhB(μ-N-t-Bu)2]2 (1a, M= Ge; 1b, M = Sn) were determined to be spirocyclic with two orthogonal boraamidinate (bam) ligands N,N′-chelated to the group 14 centre. Oxidation of 1b with SO2Cl2 afforded the thermally unstable, blue radical cation {Sn[PhB(μ-N-t-Bu)2]2}•+, identified by electron paramagnetic resonance (EPR) spectroscopy supported by density functional theory (DFT) calculations, whereas the germanium analogue 1a was inert towards SO2Cl2. The reaction between Li2[PhB(μ-N-t-Bu)2]2 and SnCl2 or PbI2 in 2:1 molar ratio in diethyl ether produced the novel heterotrimetallic complexes Li2Sn[PhB(μ-N-t-Bu)2]2 (2b) and (Et2O·Li)LiPb[PhB(μ-N-t-Bu)…

Bond Stretching and Redox Behavior in Coinage Metal Complexes of the Dichalcogenide Dianions [(SPh2P)2CEEC(PPh2S)2]2− (E=S, Se): Diradical Character …

2011

The metathetical reactions of a) [Li(tmeda)]2[(S)C(PPh2S)2] (Li2⋅3 c) with CuCl2 and b) [Li(tmeda)]2[(SPh2P)2CSSC(PPh2S)2] (Li2⋅4 c) with two equivalents of CuCl both afford the binuclear CuI complex {Cu2[(SPh2P)2CSSC(PPh2S)2]} (5 c). The elongated (C)S[BOND]S(C) bond (ca. 2.54 and 2.72 Å) of the dianionic ligand observed in the solid-state structure of 5 c indicate the presence of diradical character as supported by theoretical analyses. The treatment of [Li(tmeda)]2[(SPh2P)2CSeSeC(PPh2S)2] (Li2⋅4 b) and Li2⋅4 c with AgOSO2CF3 produce the analogous AgI derivatives, {Ag2[(SPh2P)2CEEC(PPh2S)2]} (6 b, E=Se; 6 c, E=S), respectively. The diselenide complex 6 b exhibits notably weaker Ag[BOND]Se…

Experimental and Theoretical Investigations of Tellurium(IV) Diimides and Imidotelluroxanes: X-ray Structures of B(C6F5)3 Adducts of OTe(μ-NtBu)2TeNt…

2005

The hydrolysis of tBuNTe(μ-NtBu)2TeNtBu (1) with 1 or 2 equiv of (C6F5)3B·H2O results in the successive replacement of terminal imido groups by oxo ligands to give the telluroxane-Lewis acid adducts (C6F5)3B·OTe(μ-NtBu)2TeNtBu (2) and [(C6F5)3B·OTe(μ-NtBu)2Te(μ-O)]2 (3), which were characterized by multinuclear NMR spectroscopy and X-ray crystallography. The TeO distance in 2 is 1.870(2) Å. The di-adduct 3 involves the association of four tBuNTeO monomers to give a tetramer in which both terminal TeO groups [d(TeO) = 1.866(3) Å] are coordinated to B(C6F5)3. The central Te2O2 ring in 3 is distinctly unsymmetrical [d(TeO) = 1.912(3) and 2.088(2) Å]. The X-ray structure of (C6F5)3B·NH2tBu (4),…

In Search of the [PhB(μ-NtBu)2]2As• Radical: Experimental and Computational Investigations of the Redox Chemistry of Group 15 Bis-boraamidinates

2008

DFT calculations for the group 15 radicals [PhB(μ-NtBu)2]2M• (M = P, As, Sb, Bi) predict a pnictogen-centered SOMO with smaller contributions to the unpaired spin density arising from the nitrogen and boron atoms. The reactions of Li2[PhB(μ-NR)2] (R = tBu, Dipp) with PCl3 afforded the unsolvated complex LiP[PhB(μ-NtBu)2]2 (1a) in low yield and ClP[PhB(μ-NDipp)2] (2), both of which were structurally characterized. Efforts to produce the arsenic-centered neutral radical, [PhB(μ-NtBu)2]2As•, via oxidation of LiAs[PhB(μ-NtBu)2]2 with one-half equivalent of SO2Cl2, yielded the Zwitterionic compound [PhB(μ-NtBu)2As(μ-NtBu)2B(Cl)Ph] (3) containing one four-coordinate boron center with a B−Cl bond.…

The Nature of Transannular Interactions in E4N4 and E82+ (E = S, Se)

2012

The electronic structures of tetrachalcogen tetranitrides, E4N4, and octachalcogen dications, E82+, and the nature of their intramolecular E···E interactions (E = S, Se) was studied with high-level theoretical methods. The results reveal that the singlet ground states of both systems have a surprisingly large correlation contribution which functions to weaken and therefore lengthen the cross-ring E–E bond. The observed correlation effects are primarily static in E4N4, whereas in E82+ the dynamic part largely governs the total correlation contribution. The presented description of bonding is the first that gives an all-inclusive picture of the origin of cross-ring interactions in E4N4 and E8…

Synthesis, Spectroscopic, and Structural Investigation of the Cyclic [N(PR2E)2]+ Cations (E = Se, Te; R = iPr, Ph): the Effect of Anion and R-Group E…

2006

Two-electron oxidation of the [N(PiPr2E)2]- anion with iodine produces the cyclic [N(PiPr2E)2]+ (E = Se, Te) cations, which exhibit long E−E bonds in the iodide salts [N(PiPr2Se)2]I (4) and [N(PiPr2Te)2]I (5). The iodide salts 4 and 5 are converted to the ion-separated salts [N(PiPr2Se)2]SbF6 (6) and [N(PiPr2Te)2]SbF6 (7) upon treatment with AgSbF6. Compounds 4−7 were characterized in solution by multinuclear NMR, vibrational, and UV−visible spectroscopy supported by DFT calculations. A structural comparison of salts 4−7 and [N(PiPr2Te)2]Cl (8) confirms that the long E−E bonds in 4, 5, and 8 can be attributed primarily to the donation of electron density from a lone pair of the halide count…

Structures and EPR spectra of binary sulfur−nitrogen radicals from DFT calculations

2007

he scattered electron paramagnetic resonance (EPR) spectroscopic data for binary sulfur–nitrogen (S,N) radicals have been compiled and critically assessed.Many of these are inorganic rings or cages.For each species, possible equilibrium structures in the gas phase and the EPR hyperfine coupling (hfc) constants have been calculated with DFT using the B3LYP functional and basis sets of triple-ζ (or better) quality.Good agreement is obtained between calculated and measured values for the well characterized [S3N2]+radical dot, a planar π-radical for which the s-component of the orbitals is likely to be reasonably independent of minor geometrical changes between gas-phase and condensed-phase sta…

A Selenium-Nitrogen Chain with Selenium in Different Oxidation States

2017

The reaction of tBuNH2 with a mixture of SeCl2 and SeOCl2 in a 6:2:1 molar ratio produces the novel selenium-nitrogen chain ClSeN(tBu)Se(O)Cl (4), in which the selenium atoms are in two different oxidation states, SeII and SeIV. The crystal structure of 4 is compared with that of the related SeII/SeII system ClSeN(tBu)SeCl (1) and differences are attributed to hyperconjugative effects. The energetics of the formation of 4 via two different routes are elucidated by PBE0/def2-TZVPP calculations. peerReviewed

Experimental and Theoretical Investigations of the Redox Behavior of the Heterodichalcogenido Ligands [(EPiPr2)(TePiPr2)N]− (E = S, Se): Cyclic Catio…

2008

The two-electron oxidation of the lithium salts of the heterodichalcogenidoimidodiphosphinate anions [(EPiPr2)(TePiPr2)N]− (1a, E = S; 1b, E = Se) with iodine yields cyclic cations [(EPiPr2)(TePiPr2)N]+ as their iodide salts [(SPiPr2)(TePiPr2)N]I (2a) and [(SePiPr2)(TePiPr2)N]I (2b). The five-membered rings in 2a and 2b both display an elongated E−Te bond as a consequence of an interaction between tellurium and the iodide anion. One-electron reduction of 2a and 2b with cobaltocene produces the neutral dimers (EPiPr2NPiPr2Te−)2 (3a, E = S; 3b, E = Se), which are connected exclusively through a Te−Te bond. Two-electron reduction of 2a and 2b with 2 equiv of cobaltocene regenerates the corresp…

New tellurium-containing ring systems

2007

The recent discovery of a suitable synthesis of the monoanionic ditelluroimidodiphosphinate ligands [TePR2NPR2Te]− (R = Ph, iPr, tBu) has facilitated investigations of the fundamental chemistry of these chelating inorganic ligands. This article is focused on aspects of that chemistry in which the behaviour of this ditelluro PNP ligand differs from that of the well-studied dithio and diseleno congeners. The emphasis is on new tellurium-containing ring systems formed in: (a) redox transformations and (b) the synthesis of metal complexes. peerReviewed

CCDC 1424396: Experimental Crystal Structure Determination

2016

Related Article: Ramalingam Thirumoorthi, Tristram Chivers, Susanna Häggman, Akseli Mansikkamäki, Ian S. Morgan, Heikki M. Tuononen, Manu Lahtinen, Jari Konu|2016|Dalton Trans.|45|12691|doi:10.1039/C6DT02565J

CCDC 1424395: Experimental Crystal Structure Determination

2016

Related Article: Ramalingam Thirumoorthi, Tristram Chivers, Susanna Häggman, Akseli Mansikkamäki, Ian S. Morgan, Heikki M. Tuononen, Manu Lahtinen, Jari Konu|2016|Dalton Trans.|45|12691|doi:10.1039/C6DT02565J

CCDC 1522803: Experimental Crystal Structure Determination

2017

Related Article: Aino J. Karhu, Juho Jämsä, J. Mikko Rautiainen, Raija Oilunkaniemi, Tristram Chivers and Risto S. Laitinen|2017|Z.Anorg.Allg.Chem.|643|495|doi:10.1002/zaac.201700031

CCDC 1486829: Experimental Crystal Structure Determination

2016

Related Article: Ramalingam Thirumoorthi, Tristram Chivers, Susanna Häggman, Akseli Mansikkamäki, Ian S. Morgan, Heikki M. Tuononen, Manu Lahtinen, Jari Konu|2016|Dalton Trans.|45|12691|doi:10.1039/C6DT02565J

CCDC 1424394: Experimental Crystal Structure Determination

2016

Related Article: Ramalingam Thirumoorthi, Tristram Chivers, Susanna Häggman, Akseli Mansikkamäki, Ian S. Morgan, Heikki M. Tuononen, Manu Lahtinen, Jari Konu|2016|Dalton Trans.|45|12691|doi:10.1039/C6DT02565J