SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF THE ELECTRON-DEFICIENT METAL-CARBONYL CLUSTER )-H)(MU-H)(MU-P(T)BU(2))(2)(MU-PH(2)PCH(2)PPH(2))]

The reaction of [Os-3(CO)(10)(mu-dppm)] (1) with (t)Bu(2)PH in refluxi ng diglyme results in the electron-deficient metal cluster complex 3(C O)(5)(mu(3)-H)(mu-H)(mu-P(t)Bu(2))(2)(mu-dppm)] (2) (dppm = Ph(2)PCH(2 )PPh(2)) in good yields. The molecular structure of 2 has been establi shed by a single crystal X-ray structure analysis. In contrast to the known homologue )(CO)(4)(mu(3)-H)(mu-H)(mu-P(t)Bu(2))(2)(mu-dppm)] (3) , no bridging carbonyl ligand was found in 2. The electronically unsat urated cluster 2 does not react with carbon monoxide under elevated pr essure, therefore 2 seems to be coordinatively saturated by reason of the high steric demands of the phosphido ligands.