35Cl NQR spectra of phosphorus chlorides and their molecular conformations in crystals. Part 2. Steric effects in ArPCl2 and RPCl2 molecules

Abstract The MNDO, HF and MP2 calculations showed that in the molecules of both types, RPCl 2 ( R = CH 3 , ClCH 2 , CF 3 , CC1 3 ) and ArPCl 2 increasing of steric interactions between R and Ar radicals and chlorine atoms of the PCl 2 group leads to enhancement of s-character of LP2 orbital of the chlorine atoms. In the series RPCl 2 , in contradistinction to the series ArPCl 2 , increasing of steric interactions leads to decreasing of percentage of s-character of LP3 hybrid orbital of the chlorine atoms and increasing of LP3 donor–acceptor interactions with antibonding orbital of the P–C bond. The difference in coefficients of linear dependencies between 35 Cl NQR frequencies of the chlorine atoms of PCl 2 group and atomic charges on these atoms in the series RPCl 2 and ArPCl 2 are explained by the above mentioned distinctions. 35 Cl NQR spectrum at 77 K of CCl 3 PCl 2 have been obtained: ν( C – Cl )=38.853(2), 39.469(1) MHz , ν( P – Cl )=27.306 MHz .