Crystal and molecular structure of NN-di-isopropyl-p-phenylphosphon-amidic chloride, PPh(Cl)(NPri2)O

Abstract

Crystals of the title compound are monoclinic, with unit-cell dimensions a= 7.463(5), b= 13.72(l), c= 13.90(1)Å, and β= 100.35(5)°, space group P2₁/c, and Z= 4. The structure has been determined from three- dimensional counter data and refined to R 0.045 for 1 634 observed amplitudes. The P–N bond length [1.614(2)Å] indicates a considerable degree of π bonding, and the conformation about this bond is consistent with an n–σ* type of interaction. Comparison with structural data on related molecules shows that the π bonding is enhanced by electronegative substituents on the phosphorus atom. The two Prⁱ groups are orientated differently with respect to the P–N bond. These results are discussed in relation to n.m.r. spectroscopic data which indicate that the Prⁱ groups are non-equivalent at low temperature.