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Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала. Structures and relative energies of binuclear iron-manganese complexes with the phosphine ligand L, which exist in vinylidene Cp(CO)(L)MnFe(μ-C=CHPh)(CO)4 (2) and benzylidene ketene η4 -{C[Mn(CO)(L)Cp]⋅ ⋅(CO)CHPh}Fe(CO)3 (3) forms are calculated by the B3LYP density functional method. Four isomers with different positions of ligand L relative to the phenyl ring (conformers a and b) and the substituent Ph relative to the С=С bond (conformers E and Z) are considered for each form and their relative stability is determined. It is shown that all isomers of 2 have approximately the same energy (within 4 kcal/mol) whereas the energies of isomers of 3 differ within 21 kcal/mol. Isomer 3Ea in which the PPh3 ligand contacts with the phenyl substituent of the vinylidene group is most energetically favorable. It is found that with an increase in the L ligand size in the order PH3 < PH2Ph < PHPh2 < PPh3 the Mn–P bond length increases to 2.37 Å in the most stable isomer of form 3 and to 2.43 Å in the isomers of 2 and three conformers of 3. A more substantial increase in the Mn–P bond length in complexes 2 and 3 correlates with their lower stability as compared to isomer Ea of 3, which is consistent with experimental data on the presence of only one conformer 3Ea in solution.

The electrochemical reactions of carbonyl cluster compounds M3(CO)12 (M = Fe, Ru, Os) were compared with those of [Fe5C(CO)14]2− and [Fe6C(CO)16]2− in different aprotic solvents. The stability of electrochemically generated products of these clusters in the studied solvents was shown to grow in the following order: tetrahydrofuran < acetone < dichloromethane < acetonitrile.

The electrochemical behavior of the heteronuclear dimeric vinylidene complex [Cp(CO)2MnCu(μ-C=CHPh)(μ-Cl)]2 (I) is studied using polarography, cyclic voltammetry, and controlled-potential electrolysis on mercury and platinum electrodes in acetonitrile. The dimer is reduced in two two-electron stages: at the first stage, metal-halogen bonds are broken and binuclear monomers [Cp(CO)2MnCu(μ-C=CHPh)(Cl)]− are formed; at the second stage, mononuclear manganese complexes Cp(CO)2Mn=C=CHPh, metallic copper, and chloride ions are formed. The two-electron oxidation of dimer [Cp(CO)2MnCu(μ-C=CHPh)(μ-Cl)]2 also results in the formation of binuclear monomers, which decompose to complex Cp(CO)2Mn=C=CHPh, Cu2+ ions, and Cl− ions.

The potential energy profile of the full catalytic cycle of methanol carbonylation catalyzed by [Rh(CO)2I2]- complex was explored computationally using a gradient-corrected density functional method. The equilibrium structures of all isomers of the intermediates involved in the catalytic process have been calculated. The transition states of CH3I oxidative addition, the CO migratory insertion, and the CH3COI reductive elimination were also located. The rate-determining step of the reaction, CH3I oxidative addition, was found to proceed via a back-side SN2 mechanism. The activation barrier of CO migratory insertion is calculated lower than that of CH3I reductive elimination; this finding confirms the hypothesis that the unstable nature of the complex [RhCH3(CO)2I3]- is mainly due to its fast decomposition into the acyl species. The trans conformers of the six-coordinated intermediates [RhCH3(CO)2I3]- and [Rh(CH3CO)(CO)2I3]- are more stable than their cis conformers. The activation barriers of CO migratory ...