Structure and Relative Stability of Isomers of Rhenium and Molybdenum Oxo- and Oxohydroxoalkoxo Derivatives Re_xMo_4–xO_6–n(ОН)_n(OMe)₁₀ (х = 0–4, n = 1, 2, 4)

Quantum chemical methods have been used to calculate heteronuclear rhenium and molybdenum oxo-alkoxo complexes (Re_xMo_4–xO₆(OMe)₁₀) and oxohydroxoalkoxo complexes (Re_xMo_4–xO_6–n(ОН)_n(OMe)₁₀, n = 1, 2, 4). The core of the clusters is a rhombus composed of four metal atoms connected by bridging oxygen atoms along the sides and the short diagonal. Alkoxo groups occupy terminal positions. The structure and relative stability of the isomers corresponding to different positions of the heterometal atoms at the vertices of the rhombus have been calculated. The theoretical differences in total energies relative to the most stable isomer, the metal-metal bond lengths, bond order indices and the sum of these indices for each isomer have been determined. It has been found that in some cases, along with the bridging M–O–M' bonds, direct metal-metal bonds are also formed.