Reactions of a Gallium-Bridged Diiron Complex with Alkyl Lithium, HCl, and Phosphines

Gallium-bridged diiron complex Cp*(dppe)FeGaFe(CO)4 (2, Cp* = η-C5Me5, dppe = Ph2CH2CH2PPh2) did not react with [PPN]Cl, DMAP (4-N,N-dimethylaminopyridine), and bpy (2,2′-bipyridine); however, reaction of 2 with HCl caused Ga−Fe(CO)4 bond fission to give Cp*(dppe)FeGaCl2 (4). The Ga−Fe(CO)4 bond cleavage also occurred by the reaction of 2 with RLi (R = Me, nBu) to afford Cp*(dppe)FeGaR2 (R = Me (5a), nBu (5b)). Irradiation of 2 in the presence of phosphine PR3 (R = OPh, Me, and OMe) gave Cp*(dppe)FeGaFe(CO)3L (L = P(OPh)3 (6a), PMe3 (6b), and P(OMe)3 (6c)) and Cp*(dppe)FeGaFe(CO)2L2 (L = PMe3 (7b) and P(OMe)3 (7c)) depending on the reaction conditions. Cleavage of the Cp*(dppe)Fe−Ga bond occurred by irradiation of 2 in the absence of PR3 to give hydridoiron complex Cp*(dppe)FeH (8) via abstraction of hydrogen from solvent. Structural investigation of 6a and 6b revealed that substitution of CO with an electron-releasing ligand PR3 caused shortening of the Ga−Fe(CO)3L bond and elongation of the Cp*(dppe)Fe−Ga bond.