Photoinduced Formal Gallylene Transfer from Gallium-Bridged Dimetallic Complexes to 16-Electron Metal Fragments

Photoirradiation of the mixtures of Cp′(dppe)­FeGaM­(CO)5 (Cp′ = η5-C5Me5 (Cp*), M = W (2), Cr (3); Cp′ = η5-C5H5 (Cp), M = W (5), Cr (6)) and Fe­(CO)5 in C6D6 caused formal gallylene transfer from 2, 3, 5, and 6 to the Fe­(CO)4 fragment to afford the gallium-bridged diiron complexes Cp′(dppe)­FeGaFe­(CO)4 (Cp′ = Cp* (1), Cp (4)) in moderate yields. Gallylene transfers with Cp­(dppe)­FeGaFe­(CO)4 (4) and M­(CO)6 (M = W, Cr) also took place to produce 5 and 6, respectively; however, that with Cp*­(dppe)­FeGaFe­(CO)4 (1) and M­(CO)6 did not proceed. Photoirradiation of 4 alone in toluene caused CO dissociation and dimerization to afford the gallylene-bridged tetrametallic complex {μ-Cp­(dppe)­FeGa}2Fe2(CO)6(μ-CO) (8). In contrast to 4, the Cp* analogue 1 gave no gallylene-bridged complex in a similar reaction.