An electronic perspective on the reduction of an n=n double bond at a conserved dimolybdenum core.
Density functional theory has been used to assess the role of the bimetallic core in supporting reductive cleavage of the N=N double bond in [Cp2Mo2(mu-SMe)3(mu-eta1:eta1-HN=NPh)]+. The HOMO of the complex, the Mo-Mo delta orbital, plays a key role as a source of high-energy electrons, available for transfer into the vacant orbitals of the N=N unit. As a result, the metal centres cycle between the Mo(III) and Mo(IV) oxidation states. The symmetry of the Mo-Mo delta "buffer" orbital has a profound influence on the reaction pathway, because significant overlap with the redox-active orbital on the N=N unit (pi* or sigma*) is required for efficient electron transfer. The orthogonality of the Mo-Mo delta and N-N sigma* orbitals in the eta1:eta1 coordination mode ensures that electron transfer into the N-N sigma bond is effectively blocked, and a rate-limiting eta1:eta1-->eta1 rearrangement is a necessary precursor to cleavage of the bond.
Padden Metzker
Julia K
JK
Department of Chemistry, The University of York, Heslington, York, YO10 5DD, UK.
McGrady
John E
JE
D004563:Electrochemistry / Q000379:methods; D008958:Models, Molecular; D008968:Molecular Conformation; D008982:Molybdenum; D009584:Nitrogen; D010084:Oxidation-Reduction
D008982:Molybdenum; D009584:Nitrogen