CLUSTER CHEMISTRY .98. FORMATION OF AN RU-5-DICARBON COMPLEX - X-RAY STRUCTURES OF RU-5(MU(5)-C-2)(MU-PPH(2))(2)(MU-CL)(2)(CO)(11) AND (MU-H)(MU(5)-CC(PPH(2)))(MU-CL)(MU-PPH(2))(CO)(12)

Reaction of Ru-5(mu(5)-C(2)PPh(2))(mu-PPh(2))(CO)(13) (1) with 5-chlor o-4-chloromethyl-2,4-dimethylpent-1-ene in refluxing CHCl3 affords Ru- 5(mu(5)-C-2)(mu-PPh(2))(2)(mu-Cl)(2)(CO)(11) (3) and (mu-H)(mu(5)-CC(P Ph(2)))(mu-Cl)(mu-PPh(2))(CO)(12) (4). The crystal structures of 3 and 4 were determined by X-ray crystallography. Complex 3 is the second e xample of a cluster containing a C-2 ligand sitting on top of a partia lly disordered puckered pentagonal Ru-5 cluster, with one carbon stron gly bonded (sigma) to one Ru atom(Ru-C, 1.937 (9) Angstrom) with the C -2 moiety interacting in pi fashion with the other four metal atoms. C omplex 4 retains the C(2)PPh(2) ligand of the precursor, sitting on an ''open-envelope'' Ru-5 cluster; one carbon is strongly bonded to four Ru atoms of a pseudosquare Ru-4 array.