Redox properties of dihalogermylenes, dihalostannylenes and their complexes with Lewis bases

Article abstract of DOI:10.1016/0022-328X(95)00320-P

Reduction and oxidation potentials of Gel2, GeBr2 * B (B = dioxane, PPh3), GeCl2 * B (B = dioxane, PPh3, AsPh3, Py, dip), SnCl2 * dioxane, SnX2 (X = F, Cl Br, I) were measured in MeCN at 20 deg C.The data obtained indicate that in many cases the EX₂ and EX₂ * B (E = Ge, Sn) can act not only as a good reducing agents, but also as strong oxidants.Examples of redox reactions in which EX₂ and EX₂ * B react as oxidizing agents were found.The variation of the redox potentials of the dihalogermylenes and dihalostannylenes with complexation and with the nature of the halogen substituent and the Lewis base is discussed.In some cases (GeI2, GeX2 * B; X = Cl, Br, B = dioxane, PPh3), the reduction or oxidation was found to be quasi-reversible, indicating the presence of relatively stable ion radicals.AM1 calculations on GeCl2 * dioxane and GeCl2 * PH3 complexes show that the complexation destabilizes both the highest occupied and the lowest unoccupied MOs of the carbene analogues.The complexation reduces the IP and lowers the oxidation potential; its intluence on the electron affinity is not straightforward.Calculations of the ion radicals of GeCl2 and GeCl2 * B (B = dioxane, PH3 ) show that in the ground state an unpaired electron occupies ?-MO in the cation and ?-MO in anion radicals.Keywords: Germanium; Tin; Germylenes; Stannylene; Electrochemistry; AM1 calculations