COMPLEXES OF TRIS(N-PIPERIDINOMETHYL) PHOSPHINE OXIDE WITH ZINC AND CADMIUM

A number of compounds which can by their stoichiometry be classified i nto several groups have been prepared by reaction of tris(N-piperidino methyl)phosphine oxide (tppo) with Zn(II) and Cd(II) salts. The struct ure of two Zn(II) complexes differing by their Zn : tppo ratio and of one Cd(II) complex has been determined by the X-ray diffraction techni que. The results show that in all the cases tppo is bound as divalent chelate N,O-donor, but the geometry of coordination sphere of M(II) de cisively affects the steric arrangement of the five-membered chelate r ing. Structures of the compounds studied are entirely different from t hose of Zn(II) complexes of sterically less demanding P,P-dimethyl-P-a minomethylphosphine oxide (dmao). On the other hand, the way of coordi nation of tppo is the same as that found in the case of the Co(II) com plex of tris(N,N-dimethylaminomethyl)phosphine oxide.