Electronic communication between carbon chain bridged metals: a theoretical approach. Even Chains

Abstract

A theoretical investigation (DFT) allowed us to single out the most appropriate valence structure for the [M–C_x–M] unit in a variety of model compounds [{Cp(CO)₂M}₂(µ-C_x)] (M = Cr, Mn or Fe; x = 2–8) and to foresee it on the basis of the molecular parameters, such as (i) the chain length, (ii) the nature of the metal and its oxidation state, (iii) the dⁿ configuration and the metal co-ordination number. The valence structure of the [M–C_x–M] unit is diagnostic of the metal-to-metal communication. A simple electron-counting scheme has been developed to predict the valence structure, based on the dⁿ configuration of the ML_m fragments and the number of p_π electrons of the linear C_x unit.