Intramolecular C-H bond activation in bridged dicyclopentadienyl dimethyl dinuclear complexes

Article abstract of DOI:10.1021/om400986a

Photolysis of the doubly bridged dicyclopentadienyl dimethyl dinuclear complexes [(η⁵-C₅H₂R)₂(SiMe ₂)₂]M₂(CO)₄Me₂ (M = Ru, R = H (2a), ^tBu (2b); M = Fe, R = H (2c)) in benzene yields the corresponding methylene-bridged complexes [(η⁵-C ₅H₂R)₂(SiMe₂)₂]M ₂(CO)₂(μ-CO)(μ-CH₂) (3a-c) and the M-M-bonded complexes [(η⁵-C₅H₂R) ₂(SiMe₂)₂]M₂(CO)₄ (1a-c). Irradiation of the analogous diethyl complex [(η⁵-C ₅H₂R)₂(SiMe₂)₂]Ru ₂(CO)₄Et₂ (4) affords only 1a. Unlike the case for the doubly bridged complexes, photolysis of the singly bridged dicyclopentadienyl dimethyl diruthenium complexes [(η⁵-C ₅H₄)₂(EMe₂)]Ru₂(CO) ₄Me₂ (E = C (5a); E = Si (5b)) in benzene yields the corresponding twisted ruthenium methyl complexes with a cyclopentadienyl-Ru σ bond (η⁵,η⁵: η¹-C₅H₄(EMe₂)C₅H ₃)[Ru(CO)₂][Ru(CO)₂Me] (6a,b) and the similar phenyl complexes (η⁵,η⁵:η¹-C ₅H₄(EMe₂)C₅H₃)[Ru(CO) ₂][Ru(CO)₂Ph] (7a,b), from reaction with the benzene solvent. Plausible mechanisms for the formation of the different types of products are proposed involving intramolecular C-H bond activation. The molecular structures of 2a,c, 3a,c, 4, 5a, 6a, and 7b, determined by X-ray diffraction, are also presented.