The effect of thiophene ring substitution position on the properties and electrochemical behaviour of alkyne–dicobaltcarbonylthiophene complexes

A large number of Co2(CO)6-Co2(CO)6- and Co2(CO)4(L-L)-substituted alkyne complexes (L-L = dppa and dmpm) have been prepared, characterized and studied by cyclic and square-wave voltammetry. In this paper we report a comparative electrochemical study of 2,5-, 2,4-, 3,4- and 2,3-bis(trimethylsilylethynyl)thiophene dicobalt substituted alkyne complexes, in order to evaluate the extent of the electronic interaction between the “Co2C2” redox centres depending on the position of the alkynyl substituent on the thiophene ring.