Molecular and electronic structure of (η5-pentaalkyl-2,3-dihydro-1,3-diborolyl)(η5-pentamethylcyclopentadienyl)metal complexes, M = Fe, Ru

The X-ray diffraction study of the Ru sandwich derivative 2b revealed a folding along the B⋯B vector of the heterocycle of 40.7°, which is due to electronic factors. The molecular and electronic structure of iron and ruthenium complexes have been studied by density functional theory (DFT) with the B3LYP functional and extended triple-ζ basis sets. The model complexes with a planar diborolyl ligand 1′ (M = Fe) and 2′ (M = Ru) are by 24.9 and 24.5 kcal/mol less stable than the equilibrium folded structures of 1 and 2, respectively.