PREPARATION AND PROPERTIES OF PHOSPHANE-B ORANES DERIVED FROM POLYFUNCTIONAL PHOSPHANES - CRYSTAL-STRUCTURES OF BIS(BORANATODIPHENYLPHOSPHONIO)METHANE AND ETRAKIS[(BORANATODIPHENYLPHOSPHONIO)METHYL]METHANE

Bis(boranatodiphenylphosphonio)methane has been prepared in pure form from Ph2PCH2PPh2 (dppm) via two synthetic routes and its crystal struc ture determined. The molecule adopts a conformation very similar to th at of the parent dppm ligand, which reflects the influences of the rep ulsive charges in the functional groups. Analogous phosphine-boranes w ere obtained from 1, 1, 1-tris(diphenylphosphinomethyl)ethane and tetr akis(diphenylphosphinomethyl)methane. The crystal structure has also b een determined for the tetra-borylated derivative of the latter. A hig hly symmetrical arrangement has been found which corresponds to a rela xed conformation of the four dipolar groups. From C(CH2PPh2)4 and H2BB r . SMe2 an ionic, spirobicyclic product was obtained, which resembles the monocyclic analogues previously described in its properties and s pectroscopic data.