Reprinted from J. Am. Chem. Soc. 120, 1172-1178 (1998).

1998, American Chemical Society

Direct Detection of 1,1-Diphenylgermene in Solution and Absolute Rate Constants for Germene Trapping Reactions

N.P. Toltl and W. J. Leigh*

Contribution from the Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1

Abstract: Direct irradiation of 1,1-diphenylgermetane in hexane solution affords 1,1,3,3-tetraphenyl-1,3-digermetane in high chemical yield. Photolysis in the presence of aliphatic alcohols leads instead to the formation of the corresponding alkoxymethyldiphenylgermane. These results are consistent with the formation of 1,1-diphenylgermene as a primary photochemical product from photolysis of the germetane. Nanosecond laser flash photolysis of the germetane in hexane, acetonitrile and tetrahydrofuran gives rise to the formation of a transient, assignable to the germene on the basis of its second order decay kinetics, UV spectrum (lmax = 325-nm), and the fact that it is quenched by addition of alcohols and acetic acid. Absolute rate constants for reaction of 1,1-diphenylgermene with methanol, ethanol, 2-propanol, t-butanol, acetic acid, the O-deuterated isotopomers, and acetone have been determined in the three solvents, using the germetane as the precursor. The kinetics and mechanisms of these germene trapping reactions are discussed and compared to those of silenes.