METALLOPHOSPHANE OXIDES AND METALLOPHOSPHANE SULFIDES DERIVED FROM NIOBOCENE OR TANTALOCENE - SYNTHESIS OF HETEROBIMETALLIC COMPLEXES CP2M(CO) (MU, ETA(1)-ETA(1)-PR2S) M'L(N) WITH M=NB OR TA AND M'=CR, MN, FE

The metallophosphanes Cp2M(CO)(PR2) (with M=Nb, Ta and R=Me, Ph) react with H2O2 or S8 leading to the corresponding metallophosphane oxides and metallophosphane sulfides. The sulfides are able to bind electron- deficient fragments (Cr(CO)5, CpMn(CO)2 or Fe(CO)4). This affords a ne w class of bimetallic complexes CP2M(CO)(mu, eta1:eta1-PR2S)M'L(n).