Crystal and molecular structure of cis-2,2,3,4,4-pentamethyl-1-phenylphosphetan 1-oxide, C14H21PO

Abstract

cis-2,2,3,4,4-Pentamethyl-1-phenylphosphetan 1-oxide crystallizes in the space group P2₁/c with Z= 4 in a unit cell of dimensions a= 6·350(2), b= 15·750(5), c= 14·305(4)Å, and β= 106·07°(2). Intensities of 1785 independent reflections were measured on a diffractometer. The crystal structure has been elucidated using the phosphorus atom as a phase-determining heavy atom, and refined by full-matrix least-squares methods to R 4·1%, for 1188 observed reflections. The bond angles around the phosphorus atom are considerably distorted from tetrahedral, ranging from 81·3 to 117·8°, the small angle being in the heterocyclic ring. The phosphetan ring is puckered with a dihedral angle of 23·8°. The methyl group at C(3) is cis to the phenyl ring.