Electrochemistry of complexes of dichlorogermylene and dihalostannylenes with chromium, molybdenum, and tungsten pentacarbonyls

Electrochemical behaviour of the transition metal complexes of dichlorogerm ylene and dihalostannylenes, (CO)(5)M=EX2 . B (M = Cr, Mo, W; E = Ge, X = C l; E = Sn, X = Cl, Pr, I; B = THF, dioxane, DMF) has been studied in MeCN a t 20 degrees C. Both the reduction and the oxidation processes were found t o be irreversible suggesting that the corresponding radical ions were unsta ble under these conditions; mechanisms of reduction and oxidation of (CO)(5 )M=EX2 . B were proposed. Electrochemical data obtained show that the elect ronic structures of (CO)(5)M=EX2 . B complexes are similar to those of Fisc her transition metal carbene complexes. Cyclic voltammetry data of (CO)(5)M =GeCl2 . B (M = Cr, W; B = THF, dioxane, DMF) in DMF solutions clearly test ify to the fact that the solvolytic cleavage of M=Ge bond in these complexe s takes place leading to (CO),M DMF and GeCl2 . DMF species formation. The reduction of GeCl2 . dioxane complex in DMF is discussed. (C) 1999 Publishe d by Elsevier Science S.A. All rights reserved.