P~(IV)-P~V Coordination Isomersim of Cyclic Phosphorus P-Chloro Imines

摘要

The structure of 5-chloromethyl-substituted 1,3,2gamma~5-diazaphosphorines Cl_2P(NCR)_2CC(Cl)R_2' (R = H, Cl; R' = Cl, F, CN) and their 1:2 solvates with chloroform, and alternative chlorotropy pathways in these compounds with variation of the phosphorus coordination number P~(IV)-P~V were studied by semiempirical MNDO-PM3 calculations in the supermolecular approximation. A possibility for isolating metastable P~V isomers Cl_3P(N=CR)_2C=CR_2' containing two imine nitrogen atoms in the equatorial positions of the trigonal bipyramid of phosphorus was demonstrated. The models of limited specific solvation of sigmatropic transition states of P-chlorodiazaphosphorines and related bipolar phosphorus halides were examined. Specific solvation levels out the preferableness of the 1,5-sigmatropic transformation of 5-chloromethyl-1,3,2gamma~5-diazaphosphorines via unstable intermediate [NC(Cl)R]C=CR_2' over the direct, P,C migration of chlorine.