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Rational synthesis of Molybdenum(V) tetramers consisting of [Mo2O4](2+) dimers held together by bridging phosphinate ligands and the Tungsten(VI) dimer [(CH3O)(2)(O)W(mu-O)(mu-O2PPh2)(2)W(O)(CH3O)(2)]: Structural and theoretical considerations

Authors:
Jimtaisong, A.
Feng, L. S.
Sreehari, S.
Bayse, C. A.
Luck, R. L.
Published by: Journal of Cluster Science
Date: 3 2008
Volume, Number, Pages: 19 1 181-195

Accession Number:

Abstract:

Reacting MoO2(acac)(2) with Ph2POOH or Me2POOH in EtOH results in the formation of the tetranuclear molybdenum (V) clusters Mo-4(mu (3)-O)(4)(mu-O2PR2)(4)O-4, PR2 = PPh2, 1, or PMe2, 2, in functional yields (> 90% and 55% respectively). The reaction of WO2(acac)(2) with Ph2POOH in MeOH affords the tungsten dimer [(CH3O)(2)(O)W(mu-O)(mu-O2PPh2)(2)W(O)(CH3O)(2)], 3. The single crystal X-ray determined structures of complexes 1-3 are reported. In 1 and 2, the four Mo=O units are interconnected by four triply bridging oxygen atoms, resulting in a distorted cubic-like structure for the Mo-4(mu (3)-O)(4)O-4 units. Each molybdenum atom forms two additional Mo-O bonds with two oxygen atoms from different adjacent phosphinato ligands. Complex 3, a tungsten dimer, contains packing disorder and consists of bridging oxo and diphenylphosphinato ligands. The bonding of 1 and 2 assessed by density-functional methods showed that bonding between the Mo(V) centers occurs through sigma overlap of the d(xy) orbitals.