The catalytic chemistry of [Mo2]4+ compounds has been unexplored due to the inherent difficulty in functionalizing their axial positions.  Here, we explore the use of Lewis acids to create heterotrimetallic [Mo2]4+ complexes with unprecedentedly high affinity for axial ligands through synthesis and characterization of five new [Mo2]4+ complexes: trans-2,2-dimolybdenum-tetra(6-thioxo-2-piperidinone) (2,2-Mo2(SNO6)4); trans-2,2-dimolybdenum-tetra(monothiosuccinimide) (2,2-Mo2(SNO5)4); 4,0-dimolybdenum-tetra(monothiosuccinimide) (4,0-Mo2(SNO5)4); 4,0-lithium dimolybdenum-tetra(6-thioxo-2-piperidinone)chloride (4,0-LiMo2(SNO6)4Cl); 4,0-lithium dimolybdenum-tetra(monothiosuccinimide) (4,0-LiMo2(SNO5)4Cl).  These complexes use supporting ligands containing both hard and soft bases to form linear heterotrimetallic complexes between a hard Lewis acid and a softer [Mo2]4+ core.   X-ray crystallographic studies show that lithium increases the Lewis-acidity of [Mo2]4+, resulting in exceptionally short axial [Mo2]4+-Cl bond lengths (4,0-LiMo2(SNO6)4Cl = 2.715(2) �, 4,0-LiMo2(SNO5)4Cl = 2.6436(12) �).  This result is supported by DFT calculations, which show polarization of metal-metal bonding/antibonding molecular orbitals in the lithiated complexes. This polarization increases the affinity of [Mo2]4+ for axial ligands, which will expand the chemistry of [Mo2]4+.

Lewis acid activated axial functionalization of [Mo<sub>2</sub>]<sup>4+</sup> complexes

245th National Meeting (2013)

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Lewis acid activated axial functionalization of [Mo2]4+ complexes

Lewis acid activated axial functionalization of [Mo₂]⁴⁺ complexes