Search results for "Protonation"
showing 10 items of 583 documents
Acylchalcogenourea Complexes of Silver(I)
2016
Acylthio- or acylselenoureas react with silver(I) oxide to form tetranuclear silver(I) complexes containing the deprotonated acylchalcogenourea ligands bound to the silver atoms through the chalcogen and oxygen atoms. These tetrasilver(I) species react with either 4 or 8 equiv. of a phosphine to afford either dinuclear silver(I) phosphine complexes or tetrahedral silver diphosphine complexes. In these compounds, the acylchalcogenourea ligands form six-membered rings by coordinating to the metal atom through the chalcogen and oxygen atoms. In one case, we observed a very rare example of an acylthiourea ligand coordinated through the nitrogen and sulfur atoms to form a four-membered ring. A s…
Synthesis and structural characterization of well-defined bis(oxamato)palladate(II) precatalysts for Suzuki and Heck reactions
2018
Abstract A family of tetra-n-butylammonium salts of bis(oxamato)palladate(II) complexes of formula (n-Bu4N)2[Pd(Lm)2]·pH2O [m = 1–9; L1 = N-phenyloxamate (pma) and p = 2 (1), L2 = N-2-methylphenyloxamate (2-Mepma) and p = 4 (2), L3 = N-4-methylphenyloxamate (4-Mepma) and p = 2 (3), L4 = N-2,3-dimethylphenyloxamate (2,3-Me2pma) and p = 3 (4), L5 = N-2,4-dimethylphenyloxamate (Me2pma) and p = 4 (5), L6 = N-2,5-dimethylphenyloxamate (2,5-Me2pma) and p = 7 (6), L7 = N-3,4-dimethylphenyloxamate (3,4-Me2pma) and p = 6 (7), L8 = N-3,5-dimethylphenyloxamate (3,5-Me2pma) and p = 5 (8)] have been prepared and characterized by spectroscopic methods. The crystal structure of 1 that has been solved by s…
The Cu(II) complex of a C-lipophilized 13aneN4 macrocycle with an additional protonable amino group as micellar anion receptor.
2009
Three 13aneN4 macrocyclic ligands have been prepared bearing a -CH(2)NHR side arm (R = H, n-C(5)H(11), n-C(10)H(21)) on a carbon atom. When Cu(2+) is complexed in the macrocyclic ring, the amino group of the side arm undergoes an acid-base protonation equilibrium but it is not able to coordinate apically the metal cation even when it is deprotonated. The Cu(2+) complex with the ligand bearing the longest appended aliphatic chain is fully confined inside Triton X-100 micelles, and its ability to bind and sequestrate a series of anions inside micelles has been studied at two different pH values, i.e. both with protonated and neutral side-arm amino group. The favourable role played by the prot…
Deprotonation of Benzoxazole and Oxazole Using Lithium Magnesates
2005
International audience; The first deprotonations of oxazole and benzoxazole using lithium magnesates are described. The reactions occurred in tetrahydrofuran at room temperature using 1/3 equiv of lithium tributylmagnesate. As 2-lithiooxazole and 2-lithiobenzoxazole, lithium tri(2-oxazolyl)magnesate and lithium tri(2-benzoxazolyl)magnesate very rapidly and completely isomerized to the more stable 2-(isocyano)enolate and 2-(isocyano)phenolate type structures, respectively, a result shown by NMR analysis. The isolation of 2-substituted oxazoles and benzoxazoles in medium to good yields after electrophilic trapping was interpreted in two ways: (1) the equilibration between the open and closed…
Alkali Blues: Blue‐Emissive Alkali Metal Pyrrolates
2019
2-Iminopyrroles [HtBu L, 4-tert-butyl phenyl(pyrrol-2-ylmethylene)amine] are non-fluorescent π systems. However, they display blue fluorescence after deprotonation with alkali metal bases in the solid state and in solution at room temperature. In the solid state, the alkali metal 2-imino pyrrolates, M(tBu L), aggregate to dimers, [M(tBu L)(NCR)]2 (M=Li, R=CH3 , CH(CH3 )CNH2 ), or polymers, [M(tBu L)]n (M=Na, K). In solution (solv=CH3 CN, DMSO, THF, and toluene), solvated, uncharged monomeric species M(tBu L)(solv)m with N,N'-chelated alkali metal ions are present. Due to the electron-rich pyrrolate and the electron-poor arylimino moiety, the M(tBu L) chromophore possesses a low-energy intra…
N-Cobaltocenium Amide as Reactive Nucleophilic Reagent for Donor–Acceptor Bimetallocenes
2017
Deprotonation of the aminocobaltocenium ion [Cc-NH2]+ ([H-1]+) generates the nucleophilic imine CcNH (1). Reaction of 1 with acid chlorides R–COCl (R = Ph, Fc, and Cc+) yields the reference amide [Ph-CO-NH-Cc]+ (2+) and the amide-linked hetero- and homobimetallocenes [Fc-CO-NH-Cc]+ (3+) and [Cc-CO-NH-Cc]2+ (42+), respectively. Cation–anion interactions of charged amides 2+–42+ in the solid state and in solution are probed by single crystal X-ray diffraction and NMR and IR spectroscopy. Intramolecular metal–metal interactions in donor–acceptor heterobimetallocene 3+ and in mixed-valent homobimetallocene 4+ (prepared electrochemically) are discussed within the Marcus–Hush framework aided by s…
Iron( ii ) and cobalt( ii ) complexes based on anionic phenanthroline-imidazolate ligands: reversible single-crystal-to-single-crystal transformations
2018
A series of low-spin FeII and CoII complexes based on phenanthroline-imidazolate (PIMP) ligands are reported. The FeII complex (H9O4)[Fe(PIMP)3]·(C4H10O)2(H2O) (1a) shows reversible crystalline phase transformations to afford two new phases (H9O4)[Fe(PIMP)3]·(H2O) (1b) and (H9O4)[Fe(PIMP)3]·(C8H18O)(C4H10O)(H2O) (1c) by release of diethyl ether and absorption of diethyl/dibutyl ether, respectively. This reversible uptake/release of solvent molecules is a clear example of single-crystal-to-single-crystal transformation involving a discrete metal complex. On the other hand, the corresponding CoII complex (H9O4)[Co(PIMP)3]·(C4H10O)2(H2O)2 (2) does not exhibit similar phase transformations. In …
Nature of (C5Me5)2Mo2O5in water–methanol at pH 0–14. On the existence of (C5Me5)MoO2(OH) and (C5Me5)MoO2+: a stopped-flow kinetic analysis
2002
A stopped-flow analysis of compound Cp*2Mo2O5 (Cp* = η5-C5Me5) in 20% MeOH–H2O over the pH range 0–14 has provided the speciation of this molecule as well as the rate and mechanism of interconversion between the various species that are present in solution. The compound is a strong electrolyte in this solvent combination, producing the Cp*MoO2+ and Cp*MoO3− ions in equilibrium with a small amount of Cp*MoO2(OH), the latter attaining ca. 15% relative amount at pH 4. At low pH ( 6. The acid dissociation constant of Cp*MoO2(OH) has been measured directly (pK = 3.65 ± 0.02) while the pK for the protonation equilibrium leading to Cp*MoO3H2+ is estimated as 5. The prevalent pathway at high pH i…
Structural and metallo selectivity in the assembly of [2 × 2] grid-type metallosupramolecular species: Mechanisms and kinetic control
2011
An unsymmetrical bis(tridentate) ligand LH in which one binding site can be readily deprotonated forms a kinetically inert [Co(III)L(2)](+) complex which can be used as a "corner" species for the "Coupe du Roi" assembly of trans,trans-[Co(2)M(2)L(4)](6+) metallogrids (M = Fe(II), Co(II), Cu(II), Zn(II)). In the mixed Co(III)/Co(II) species, the oxidation states appear to be localised. In solution, the ligand LH forms octacationic, homometallic [2 × 2] grids with the individual labile metal ions Fe(II), Co(II), Cu(II), Zn(II), seemingly as mixtures of all possible isomers arising from the unsymmetrical nature of the ligand. In the solid state, however, [Zn(4)L(4)](CF(3)SO(3))(8)·4CH(3)CN cry…
A two-dimensional coordination polymer constructed from binuclear copper(II) metalloligands and manganese(II) ions: Synthesis, crystal structure and …
2016
Abstract The self-assembly process between the binuclear [Cu2(HL)(L)]− complex and the manganese(II) ion affords a two-dimensional coordination polymer of formula [Mn{Cu2(HL)(L)}2(H2O)2]n (1) (H3L = 3-hydroxyiminomethylsalicylic acid) where parallel ladder-like motifs of defective double cubanes of bis(phenoxo)dicopper(II) units as rods and anti-syn carboxylato bridges as rungs act as ligands towards tetraaqua-manganese(II) entities through the deprotonated oxime groups. The topology of 1 is compared with the one of another compound, [Mn{Cu2(HL)(L)}2(H2O)4]·4H2O·2DMF (1′) which was obtained in different conditions by Okawa et al. (J. Chem. Soc., Dalton Trans. (2001) 3119). Magnetic suscepti…