Solvation four coordinate complexes

Four-coordinate complexes with monodentate ligands have also been reported. The X-ray crystal structures of three modifications of the compound [Au(PPh3)4]BPh4 have been determined, none of which shows the expected simple tetrahedral geometry.2540 Thus, the chloroform solvate... 

Like their aluminum counterparts, gallium alkoxides are susceptible to hydrolysis, giving Ul-defined products. Methanolysis of hydrated Ga + ions produces Ga(OMe) + and Ga(OMe)2+ in solvated forms, as well as polymeric complexes. Ga(OPh)3 reacts with boiling MeOH or EtOH to form the corresponding alkoxide. Reaction of the trialkoxide compounds with other metal alkoxides, for example, LiOR, results in the formation of four-coordinate complex anions of the type [Ga(OR)4] A recent review of sesquihahdes/oxides... 

The coordination chemistry of halocarbons is the subject of a survey by Kttlawiec and Crabtree/" and this includes a few four-coordinate compounds of palladium and platinum. Its principal concern is the activation of the halocarbons during their oxidative addition reactions to unsaturated species, but the uncertainty in the degree of solvation of three- and four-coordinate complexes by such halocarbons as CH2CI2 gives the subject some relevance to other reactions, including, of course, dissociative ligand replacements at square-planar molecules. 

Bun, Bus, Bu1) (99). The complex with R = Me crystallizes as the THF solvate [MeCu(PBu2)Li(THF)3] in which the phosphide ligand bridges the two-coordinate Cu and four-coordinate Li centers. These cuprates were found to be more thermally stable than other phosphido(alkyl)-cuprates but less reactive toward electrophiles than related cyanocu-prates. 

Mott transition, 25 170-172 paramagnetic states, 25 148-161, 165-169 continuum model, 25 159-161 ESR. studies, 25 152-157 multistate model, 25 159 optical spectra, 25 157-159 and solvated electrons, 25 138-142 quantitative theory, 25 138-142 spin-equilibria complexes, 32 2-3, see also specific complex four-coordinated d type, 32 2 implications, 32 43-44 excited states, 32 47-48 porphyrins and heme proteins, 32 48-49 electron transfer, 32 45-46 race-mization and isomerization, 32 44—45 substitution, 32 46 in solid state, 32 36-39 lifetime limits, 32 37-38 measured rates, 32 38-39 in solution, 32 22-36 static properties electronic spectra, 32 12-13 geometric structure, 32 6-11 magnetic susceptibility, 32 4-6 vibrational spectra, 32 13 summary and interpretation... 

Besides these determinations of static structures, further studies of the kinetics of oxidative addition to Ir(I) complexes have been made. Beginning with Ir(CO)H(PPh3)3 (VIII), the first step is seen as dissociation to the four-coordinate planar intermediate (IX). This then deforms and undergoes concerted cis addition to yield the adduct (V) (179,224). In a comparison of group IV hydrides, PhsMH, the rates increased in the order Sibond energy but to the effects of differing polarizability and solvation of M-Ir products on the activation energy for addition. 

The mechanisms of alkene insertions are known for some square-planar Pt(II) complexes , but it is difficult to distinguish between pathways in which a four-coordinated alkene/hydride species collapses by migratory insertion to a three-coordinated (perhaps solvated) species, and pathways in which a five-coordinated alkene/hydride collapses to a four-coordinated product. Both pathways occur, depending on the ligands. The rates of insertion of ethylene into the neutral and cationic hydrides trans-PtHX(PEt3)2 and trans-[PtHL(PEt3)2] + (X = Cl , NOj", CN L = acetone, CO, PEtj, AsPha, P(OMe)3 and P(OPh)3) leads to Scheme 1 °. 

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