122991-86-0Relevant academic research and scientific papers
Effect of ring size on NMR parameters: Cyclic bisphosphine complexes of molybdenum, tungsten, and platinum. Bond angle dependence of metal shieldings, metal-phosphorus coupling constants, and the 31P chemical shift anisotropy in the solid state
Lindner, Ekkehard,Fawzi, Riad,Mayer, Hermann August,Eichele, Klaus,Hiller, Wolfgang
, p. 1033 - 1043 (2008/10/08)
The 31P chemical shift tensors of bis(phosphine) complexes of the type [M] [Ph2P(CH2)nPPh2] ([M] = (OC)4Mo, (OC)4W, Cl2Pt; n = 1-5) and of fac-(OC)3Mo[PPh(CH2CH2PPh2) 2] were determined by solid-state NMR techniques and correlated with structural features of the compounds. δ(31P), 1JM-P, and δ(M) show a dependence on the ring size in the solution NMR spectra of the four- to six-membered chelates; for larger rings this dependence vanishes. A model for the orientation of the 31P shift tensor principal components within the molecular frame is proposed. Each tensor component displays a different dependence on the ring size; the isotropic shift is dominated by the component perpendicular to the ring plane. Changes in this component are explained in terms of variations of the M-P-C angles. Generally speaking, the behavior of each of the tensor components must be regarded as a complex interplay of all six bond angles at phosphorus. The crystal structure of (OC)4W[Ph2P(CH2)4PPh2] (2d) was determined by X-ray diffraction. Crystals of 2d are monoclinic, space group P21/n, a = 1202.8 (1) pm, b = 1531.8 (1) pm, c = 1654.1 (2) pm, β = 104.72 (1)°, and Z = 4.
