Donor properties of arylphosphines towards selenium: X-ray crystal structure of tris(m-trifluoromethylphenyl)phosphine selenide

Abstract

Crystals of the title compound are orthorhombic, space group Pbca, with a= 31.822(15), b= 11.047(6), c= 12.426(7)Å, and Z= 8. The structure was solved using multisolution direct methods and refined by least squares to R 0.054 (R′ 0.059) for 1 964 observed diffractometer data. Phosphorus adopts a distorted tetrahedral geometry with mean Se–P–C and C–P–C angles of 113.1 and 105.6° respectively. The P–Se bond length [2.094(2)Å] is the shortest reported for a tertiary phosphine selenide and is attributed to the electron-withdrawing properties of the (C₆H₄CF₃-m) groups and the consequent increased s character of the phosphorus orbital involved in bonding with selenium.