The electronic structure and bonding in W 2(μ-H) 2(O iPr) 4(DMPE) 2 and a comparison with Mo 2(O iPr) 4(DMPE) 2

Abstract

The bonding in the recently reported [1] W 2(μ-H) 2(O i Pr) 4(DMPE) 2 (O i Pr=isopropoxide; DMPE=bis(dimethylphosphino)ethane) molecule is investigated via the computational method of Fenske and Hall and the results are compared with those of a previous study of the electronic structure of Mo 2(O i Pr) 4(DMPE) 2 by Bursten and coworkers [2]. In the dimolybdenum system, a Mo–Mo triple bond of configuration σ 2π 4δ 2 nb (nb=nonbonding) unites the two molybdenum atoms of oxidation states 0 and 4+. The introduction of the two bridging hydrides reduces the metal–metal bond order to two in W 2(μ-H) 2(O i Pr) 4(DMPE) 2 and by analogy the bonding between the tungsten atoms can be described as σ 2π 2δ 2 nb. Although there is extensive mixing of the W–W and W–H σ bonds, an orbital can still be ascribed as a W–W σ bond. An analogy is made to the bonding in B 2H 4 2−, an ethane-type molecule, and to B 2H 6.