title: Binuclear cyclopentadienylrhenium hydride chemistry: terminal versus bridging hydride and cyclopentadienyl ligands.
abstract: Theoretical studies predict the lowest energy structures of the binuclear cyclopentadienylrhenium hydrides Cp2Re2H n (Cp = η(5)-C5H5; n = 4, 6, 8) to have a central doubly bridged Re2(μ-H)2 unit with terminal η(5)-Cp rings and the remaining hydrides as terminal ligands. However, the lowest energy Cp2Re2H2 structure by more than 12 kcal mol(-1) has one terminal η(5)-Cp ring, a bridging η(3),η(2)-Cp ring, and two terminal hydride ligands bonded to the same Re atom. The lowest energy hydride-free Cp2Re2 structure is a perpendicular structure with two bridging η(3),η(2)-Cp rings. The previously predicted bent singlet Cp2Re2 structure with terminal η(5)-Cp rings and a formal Re-Re sextuple bond lies ∼37 kcal mol(-1) above this lowest energy (η(3),η(2)-Cp)2Re2 structure. The thermochemistry of the CpReH n and Cp2Re2H n systems is consistent with the reported synthesis of the permethylated derivatives Cp*ReH6 and Cp*2Re2H6 (Cp* = η(5)-Me5C5) as very stable compounds. Additionally, natural bond orbital analysis, atoms-in-molecules and overlap population density-of-state in AOMIX were applied to present the existence of rhenium-rhenium multiple bonds.
authors.affiliation: School of Mechatronical Engineering, Beijing Institute of Technology, Beijing, 100081, China.
authors.forename: Xiaozhen
authors.initials: X
authors.lastname: Gao
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.forename: R Bruce
authors.initials: RB
authors.lastname: King
authors.forename: Henry F
authors.initials: HF
authors.lastname: Schaefer
mesh_terms: D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D012211:Rhenium / Q000737:chemistry*
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D012211:Rhenium