Syntheses, 95Mo NMR Spectroscopy and Structures of Distorted Cubic Mo4(μ3-O)4(μ2-O2P(CH2C6H5)2 )4O4

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Department of Chemistry


The reaction of MoO2(acac)2 and dibenzylphosphinic acid in ethanol leads to a red distorted cubic tetrameric cluster, Mo4(μ3-O)4(μ2 -O2P(CH2C6H5)2) 4O4, and a pink open mixed-valent cluster, Mo4(μ3-O)2(μ2 -O2P(CH2C6H5)2) 6O6, when the reduction is carried out at 120 and 75 °C, respectively. 95Mo NMR spectroscopy revealed a singlet for Mo4(μ3-O)4(μ2 -O2P(CH2C6H5)2) 4O4 (1) at 584.9 ppm (Δν1/2 = 4500 Hz) and two resonances for Mo4(μ3-O)2(μ2 -O2P(CH2C6H5)2) 6O6 (2) at 238.8 ppm (Δν1/2 = 1250 Hz) and 6.4 ppm (Δν1/2 = 5999 Hz), which were assigned to the Mo(V) and Mo(VI) sites, respectively. DFT geometries and 95Mo DFT-GIAO chemical shifts for Mo4(μ3-O)4(μ2 -O2P(CH3)2)4O4 (3) and Mo4(μ3-O)2(μ2-O 2P(CH3)2)6O6 (4) are consistent with X-ray crystallography and 95Mo NMR of 1 and 2. The open complex, Mo4(μ3-O)2(μ2 -O2P(CH2C6H5)2) 6O6·2(CH2Cl2), exhibits a central Mo(V)-Mo(V) single bond at 2.6217(5) Å with each Mo(V) atom bonded to one oxo (trans-disposed) terminal ligand.

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Journal of Cluster Science