Identification of Reactive Intermediates Relevantto Dimethylgermylene Group Transfer Reactions of an Anthracene-BasedPrecursor

Dimethylgermylene ([Me2Ge]) group transfer from the anthracene-based precursor dibenzo-7-dimethylgermanorbornadiene (Me2GeA; A = C14H10, anthracene) was investigated. Transfer of [Me2Ge] from Me2GeA to 2,3-dimethylbutadiene to give a dihydrogermole (2) was mediated by a platinum metallagermacycle (1), formed by oxidative addition of the platinum(0) species (Ph3P)2Pt(C2H4) into the strained Ge–C bond of Me2GeA with concomitant loss of ethylene. Metallagermacycle 1 was characterized by multinuclear NMR spectroscopy, single-crystal X-ray diffraction, and elemental analysis. The strained Ge–C bond of Me2GeA was also found to undergo an addition reaction with pyridine, resulting in the [2.2.3]-bicyclic compound 3. Kinetics experiments on both the platinum- and pyridine-promoted systems implicate low-valent dimethylgermylene-containing species as reaction intermediates.