STRUCTURE AND VIBRATIONAL FREQUENCIES OF Ph3PCl2 WITH DISCRETE SOLVENT MOLECULES AND IN GAS PHASE

Abstract

Triphenyldichlorophosphorane ( Ph 3 PCl 2) in solution was studied with cluster model of discrete water molecules and the Onsager reaction field model. The geometry of Ph 3 PCl 2– H 2 O cluster is optimized with DFT-PW91 and DZVP basis sets. A weak hydrogen bond is formed between Cl and H atom of the water molecule. The geometry data of Ph 3 PCl 2 molecule is altered due to the presence of water molecule. The bond length of P – Cl 2 increases from 2.501 Å to 2.832 Å, and the P – Cl 1 bond length decreases from 2.113 Å to 2.064 Å. Three C – P bonds have slightly changed. The geometrical parameters of the three benzene rings do not change much upon clustering. To compare with solution structure, gas structure of Ph 3 PCl 2 also was investigated. Four stationary structures were found. The trigonal bipyramidal structure C is a penta-coordinated structure and the most stable one. This is in agreement with the previous research. The trigonal bipyramidal structure C and the ionic structure A has no imaginary frequency. The structure B and structure D have an imaginary frequency of -41.9 cm-1 and -7.4 cm-1, respectively.