Heptacoordinate dithiophosphate W(II) and Mo(II) complexes of diphosphines and iodide

• Published in: Inorganica Chimica Acta Vol. 327; no. 1; pp. 169 - 178
• Main Authors: Liu, Huizhang, Calhorda, Maria José, Félix, Vitor, Drew, Michael G.B., Veiros, Luı́s F.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 10-01-2002
• Subjects: Crystal structures; DFT calculations; Molybdenum; Seven coordination; Tungsten; Seven coordination; Crystal structures; Molybdenum; Tungsten; DFT calculations
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(01)00699-5

New complexes [MI(CO)
2(dppe){S
2P(OEt)
2}] (M=W,
1a; M=Mo,
1b), [MI(CO)
2(dppm){S
2P(OEt)
2}] (M=W,
2a; M=Mo,
2b) and [W(CO)(dppe){S
2P(OEt)
2}
2][O
2dppe] (
3a), were synthesised from [MI
2(CO)
3(NCMe)
2] (M=Mo, W), after treatment with ammonium diethyldithiophosphate and phosphine under different conditions. The structure of the tungsten complexes was determined by single crystal X-ray diffraction. During the synthesis of
3a, oxidation of the phosphine took place and a molecule of oxidised phosphine occupies channels in the crystal. DFT/B3LYP calculations on models of
1a and
2a showed the capped octahedron structure, observed in most dicarbonyl complexes of this family, to be preferred by 1.4 and 2.6 kcal
mol
−1 for the dppm and the dppe complexes, respectively. Strong steric repulsions can reverse this trend, as happens with the rigid dppm ligand. Complex
1a adopts a pentagonal bipyramidal geometry, which is often found in related monocarbonyl complexes.
New complexes [MI(CO)
2{Ph
2P(CH
2)
n
PPh
2}{S
2P(OEt)
2}] (
n=1, 2) of Mo(II) and W(II), as well as [W(CO)(dppe){S
2P(OEt)
2}
2][O
2dppe], were prepared and, for W, structurally characterised. Two different ligand arrangements (
a and
b) were found. DFT/B3LYP calculations were performed in order to rationalise the results and showed that there was no strong preference for either.