Nuclear quadrupole resonance of amidinium tetrachlorophosphorates

The³⁵C1 NQR spectra and relaxation parameters of the cyclic amidinium tetrachlorophos-phorates PCl₄(NCH₃)₂CX, where X=C₆H₅ (1), CCl₃ (2), and CF₃ (3), have been studied at 77 °K. The crystal of (3) has been found to contain two coexisting phases of the compound, which consist, respectively, of zwitterionic molecules of a hexacoordinated phosphorus atom with square-pyramidal symmetry of the PCl₄ group and molecules of chlorotropic isomers with a trigonal-bipyramidal environment for the phosphorus atom. The structural features of the crystalline state and the nature of the phosphorus—ligand bonds have been discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 6, pp. 727–730, November–December, 1985.