REDOX PROPERTIES OF DIHALOGERMYLENES, DIHALOSTANNYLENES AND THEIR COMPLEXES WITH LEWIS-BASES

Reduction and oxidation potentials of GeI2, GeBr2 . B (B = dioxane, PP h(3)), GeCl2 . B (B = dioxane, PPh(3), AsPh(3), Py, dip), SnCl2 . diox ane, SnX(2) (X = F, Cl Br, I) were measured in MeCN at 20 degrees C. T he data obtained indicate that in many cases the EX(2) and EX(2) . B ( E = Ge, Sn) can act not only as a good reducing agents, but also as st rong oxidants. Examples of redox reactions in which EX(2) and EX(2) . B react as oxidizing agents were found. The variation of the redox pot entials of the dihalogermylenes and dihalostannylenes with complexatio n and with the nature of the halogen substituent and the Lewis base is discussed. In some cases (GeI2, GeX(2) . B; X = Cl, Br, B = dioxane, PPh(3)), the reduction or oxidation was found to be quasi-reversible, indicating the presence of relatively stable ion radicals. AM1 calcula tions on GeCl2 . dioxane and GeCl2 . PH3 complexes show that the compl exation destabilizes both the highest occupied and the lowest unoccupi ed MOs of the carbene analogues. The complexation reduces the IP and l owers the oxidation potential; its influence 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 sigma-MO in the cation and pi-MO in anion radicals.