Reactions of triplet carbenes with Group IVB compounds

The photoinduced reactions of diphenyldiazomethane and diazafluorene with silicon, germanium and tin hydrides and with hexamethyldisilane, tetrakis(trimethylsilyl)silane and hexabutylditin have been investigated by ESR spectroscopy. In the reactions with the metal hydrides, hydrazonyls, resulting from addition to the diazocompounds of metal-centred radicals, were observed. The latter ones were formed via hydrogen abstraction from the starting metal hydrides brought about by the photogenerated diarylcarbenes. Triplet diphenylcarbene reacted with (Me3Si)4Si and Bu6Sn2 by a radical-like displacement mechanism, the displaced cradicals being captured by the diazomethane to give easily detected hydrazonyl while photolysis of diazofluorene under the same conditions did not lead to the detection of any radical species.