Theoretical investigation of isomerization in the systems of B2H4, AlH2BH2, Al2H4 and Al2F4 with reconstruction of covalent bond X2M - MX2 in coordinate bond M+[MX4-]

Hartree-Fock calculations of potential surfaces near different structures of molecules B2H4, AlBH4 and Al2H4 as well as separate points for similar structures of molecules B2F4, AlBF4 and Al2F4 are made. It is found that molecules B2H4 and B2F4 have symmetric structure X2M-MX2 with covalent bond M-M; on the contrary, in molecules AlBH4, Al2H4 and Al2F4 salt-like structure M+[MX4-] is the most preferrential one, though isomers X2M-MX2 and XM-MX3 in hydrides AlBH4 and Al2H4 lie 6-17 kcal above it and in Al2F4- 50 kcal. It is forecasted that the salt-like strUcture M+[MX4-] will be the main one in all the rest halides M2Hal4, where Al, Ga, In, Tl