Identification of Reactive Intermediates Relevant to Dimethylgermylene Group Transfer Reactions of an Anthracene-Based Precursor

Abstract

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.