Intramolecular positional exchange of chlorine atoms in solid pentacoordinated phosphorus compounds as studied by the 35Cl NQR method

Abstract

The 35Cl NQR frequencies and the spin-lattice relaxation times have been investigated for the solid cyclic chlorophosphoranes Cl 3PO 2C 6H 4 ( I), ClP (O 2C 6H 4) 2 ( II) and CCl 3Cl 2PO 2C 6H 4 ( III) at different temperatures. In crystalline compound I, thermoactivated motion involving the chlorine atoms of the PCl bonds has been revealed. This motion is due to intramolecular positional exchange of one axial and two equatorial chlorine atoms with an activation energy of 46.5 kJ mol −1. Earlier results obtained by means of the 35Cl NQR method for chlorine positional exchange in some other solid chlorophosphoranes are summarized.