Photoinduced Reactions of (η5-C5H5)2MH3 and (η5-C5H5)2M(CO)H (M = Nb, Ta) and the Molecular Structure of (η5-C5H5)2Ta(CO)H

Article abstract of DOI:10.1021/ja00385a015

The reaction of (η⁵-C5H5)2TaCl2 with NaBH4 followed by the addition of triethylamine and carbon monoxide yields (η⁵-C5H5)2Ta(CO)H.The molecular structure of (η⁵-C5H5)2Ta(CO)H has been established by single crystal X-ray diffraction methods.The compound crystallizes in the monoclinic space group P2₁/n with a = 6.147 (3) Angstroem, b = 13.864 (6) Angstroem, c = 11.801 (5) Angstroem, β = 100.53 (3)<*>, and ρ_calcd = 2.28 g cm^-3 for Z = 4.The structure was refined to an R value of 0.089 based on 1358 observed reflections.The tantalum-bound hydrogen atom was located on a difference electron density map and fixed at the observed Ta-H length of 1.45 Angstroem. (η⁵-C5H5)2Ta(CO)H is not isostructural with the earlier reported niobium analogue.Photolyses of (η⁵-C5H5)2MH3 or (η⁵-C5H5)2M(CO)H (M = Nb, Ta) in aromatic solvents lead to a common intermediate, (η⁵-C5H5)2MH, that can react with carbon monoxide, hydrogen, or triethylphosphine.These photogenerated species are also capable of inserting into the carbon-hydrogen bonds of benzene and catalyzing the photoassisted H/D exchange between molecular hydrogen and benzene.