Preparation and structural organisation of heteroleptic tetraphenylantimony(V) complexes comprising unidentately and bidentately coordinated O,O′-dialkyldithiophosphate groups: Multinuclear (13C, 31P) CP/MAS NMR and single-crystal X-ray diffraction studie

O,O′-dipropyldithiophosphate and O,O′-di-iso-butyldithiophosphate (Dtph) tetraphenylantimony(V) complexes of the general formula [Sb(C6H5)4{S2P(OR)2}] (R = C3H7, i-C4H9) were prepared and studied by means of 13C, 31P CP/MAS NMR spectroscopy and single-crystal X-ray diffraction. Distorted octahedral and trigonal bipyramidal molecular structures have been established for prepared complexes. These unexpected structural distinctions between chemically related compounds are defined by the principally different coordination modes of O,O′-dipropyldithiophosphate and O,O′-di-iso-butyldithiophosphate ligands in their molecular structures (i.e., S,S′-bidentate chelating and S-unidentately coordinated, respectively). To characterise quantitatively phosphorus sites in both species of dithiophosphate ligands, 31P chemical shift anisotropy parameters (δaniso and η) were calculated from spinning sideband manifolds in MAS NMR spectra. The 31P chemical shift tensors for the bidentate chelating and unidentately coordinated dithiophosphate ligands display a profoundly rhombic and nearly axially symmetric characters, respectively.