Reactions of [η5-carboxycyclopentadiene][η4-tetraphenylcyclo butadiene] cobalt with alkyl and aryl tin oxides: Synthesis, structural studies and electrochemistry of novel monomeric and dimeric [η5-carboxycyclopentadiene][η4-tetraphenylcyclobutadiene]cobal

Reactions of [η5-carboxycyclopentadienyl][η4-tetraphenylcyclobutadiene] cobalt, Ph4C4CoC5H4COOH (1), with (Ph3Sn)2O, [(n-Bu)2SnO]n and (Ph2SnO)n in refluxing toluene resulted in the formation of the monomeric compound Ph3SnOC(O)C5H4CoC4Ph4 (2) and dimeric compounds n-Bu2Sn[OC(O)C5H4CoC4Ph4]2 (3) and Ph2Sn[OC(O)C5H4CoC4Ph4]2 (4), respectively. Reactions carried out in the solid state by mechanical grinding also yielded same results. Crystal structure determination and cyclic voltammetric studies of compounds 1, 2, 3 and 4 have been carried out and compared with similar ferrocene carboxylic acid derivatives. The structures and electrochemistry of these compounds are compared with analogous organotin ferrocene carboxylates. The results obtained from the reaction of 1 with alkyl and aryl tin oxides suggest that the formation of stannoxanes assemblies having more than two carboxylate units are not favored indicating that 1 is a highly sterically hindered metallocene carboxylic acid.