The unique alternation of conformationally different ('chair'-'saddle') eight-membered metallocycles [Cd2S4P2] in the chains of cadmium dialkyldithiophosphates: C-13, P-31, Cd-113 CP/MAS NMR and single-crystal X-ray diffraction studies

摘要

O,O'-Dipropyidithiophosphate and O,O'-dibutyldithiophosphate (Dtph) cadmium(II) complexes were prepared and studied by means of heteronuclear P-31, Cd-113, C-31 CP/MAS NMR spectroscopy and single-crystal X-ray diffraction. Linear-chain polynuclear structures have been established for both cadmium(II) complexes, in which each pair of equivalent dithiophosphate groups, playing the same bridging structural function, asymmetrically links the neighbouring cadmium atoms. One remarkable structural feature of the synthesised cadmium(II) compounds is defined by the alternation of two types of conformationally different ('chair'-'saddle') eight-membered rings [Cd2S4P2] in the polymeric chains. Therefore, in both P-31 NMR and XRD data, the bridging dithiophosphate ligands exhibit structural inequivalence in pairs. The structural states of both Dtph ligands and cadmium atoms have been characterised by the P-31 and Cd-113 chemical shift tensors, which display a profound axially symmetric and mainly rhombic characters, respectively. All experimental P-31 resonances were assigned to the phosphorus structural sites in both resolved structures. (c) 2005 Elsevier B.V. All rights reserved.