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An Electronic Perspective on the Reduction of an NN Double Bond at a Conserved Dimolybdenum Core
Author(s) -
Padden Metzker Julia K.,
McGrady John E.
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400580
Subject(s) - atomic orbital , chemistry , electron transfer , crystallography , bimetallic strip , density functional theory , molybdenum , metal , molecular orbital , bond cleavage , redox , electron , computational chemistry , molecule , photochemistry , physics , inorganic chemistry , catalysis , quantum mechanics , organic chemistry , biochemistry
Density functional theory has been used to assess the role of the bimetallic core in supporting reductive cleavage of the NN double bond in [Cp 2 Mo 2 (μ‐SMe) 3 (μ‐η 1 :η 1 ‐HNNPh)] + . The HOMO of the complex, the Mo–Mo δ orbital, plays a key role as a source of high‐energy electrons, available for transfer into the vacant orbitals of the NN unit. As a result, the metal centres cycle between the Mo III and Mo IV oxidation states. The symmetry of the Mo–Mo δ “buffer” orbital has a profound influence on the reaction pathway, because significant overlap with the redox‐active orbital on the NN unit (π* or σ*) is required for efficient electron transfer. The orthogonality of the Mo–Mo δ and N–N σ* orbitals in the η 1 :η 1 coordination mode ensures that electron transfer into the N–N σ bond is effectively blocked, and a rate‐limiting η 1 :η 1 →η 1 rearrangement is a necessary precursor to cleavage of the bond.