REACTIONS OF THE LINEAR TRIOSMIUM CLUSTER [OS3H(CO)(11)(ETA(2)-C6F5NNNC6F5)] WITH [OS-3(CO)(12-N)(NCME)(N)] (N=1 OR 2) - CRYSTAL-STRUCTURESOF [OS-4(MU-H)-(CO)(14)(ETA(2)-C6F5NNNC6F5)] AND [OS-5(MU-H)(CO)(17)(ETA(2)-C6F5NNNC6F5)]

Reaction of the linear triosmium carbonyl cluster [Os3H(CO)(11)(eta(2) -C6F5NNNC6F5)] with [Os-3(CO)(11)-(NCMe)] in hexane at 60 degrees C un der vacuum afforded the 'spiked' tetraosmium cluster [Os-4(mu-H)(CO)(1 4)(eta(2)-C6F5NNNC6F5)] 1. Reaction with [Os-3(CO)(10)(NCMe)(2)] in CH 2Cl2 at room temperature gave the 'spiked' hexaosmium cluster [Os-6(mu -H)(CO)(21)(NCMe)(eta(2)-C6F5NNNC6F5)] 2. Cluster 2 is reactive and co nverts into the 'spiked' pentaosmium cluster [Os-5(mu-H)(CO)(17)(eta(2 )-C6F5NNNC6F5)] 3 and a known cluster [Os-5(CO)(16)] respectively when heated with and without C6F5N=NNHC6F5. Clusters 1 and 3 were characte rized by single-crystal X-ray crystallography. The structure of 1 cons ists of a triangular unit with a Os(CO)(3)(eta(2)-C6F5NNNC6F5) portion 'spiked' equatorially to it. The two nitrogen atoms in the triazenide ligand occupy an axial and an equatorial position in the Os(CO)(3)(et a(2)-C6F5NNNC6F5) group. The hydride ligand bridges, in a cis manner, the Os-Os edge where the Os(CO)(3)(eta(2)-C6F5NNNC6F5) portion is atta ched. The structure of 3 adopts a '4 + 1 spiked' geometry hitherto unk nown. Its metal core consists of a planar 'kite-like' Os-4 unit with t he Os(CO)(3)(eta(2)-C6F5NNNC6F5) portion 'spiked' to one of the equato rial co-ordination sites of an osmium atom. The two nitrogen atoms in the triazenide ligand and the hydride are bonded as in cluster 1. Base d upon C-13 NMR studies, the structure of cluster 2 in solution was al so deduced to have a 'spiked' feature with the linear triosmium fragme nt Os-3(CO)(11)(eta(2)-C6F5NNNC6F5) bound to one atom in the osmium tr iangle at an equatorial co-ordination site. The transformation of clus ter 2 and the formation of cluster 1 are also briefly discussed.