TRIOSMIUM CLUSTER COMPOUNDS CONTAINING ISOCYANIDE AND HYDRIDE LIGANDS - CRYSTAL AND MOLECULAR-STRUCTURES OF (MU-H)(H)OS3(CO)10(CN-T-C4H9) AND (MU-H)2OS3(CO)9(CN-T-C4H9)

The structures of the compounds (µ-H)(H)Os3(CO)10(CN-t-C4H9) and (µ-H)2Os3(CO)9(CN-t-C4H9) have been revealed by X-ray crystallographic techniques. For (µ-H)(H)Os3(CO)10(CN-t-C4H9): a = 9.064 (3), b = 12.225 (3), c = 20.364 (4) Å; β = 98.73 (3)°; space group P21/e [C2hA5], No. 14; Z = 4; dcalcd = 2.79 g cm-3. This compound contains a triangular cluster of three osmium atoms; Os(1)-Os(2) = 2.930 (1) Å, Os(1)-Os(3) = 2.876 (1) Å, and Os(2)-Os(3) = 3.000 (1) Å. There are ten linear terminal carbonyl groups and one linear terminal isocyanide ligand which occupies an axial coordination site. The hydrogen atoms were not observed crystallographically, but their positions are strongly inferred from considerations of molecular geometry. For (µ-H)2Os3(CO)9(CN-t-C4H9): a = 15.220 (8), b = 12.093 (6), c = 23.454 (5) Å; space group Pbcn [D2h 14], No. 60; Z=8; dcalcd = 2.79 g cm-3. The compound is analogous to the parent carbonyl (µ-H)2Os3(CO)10 and has two normal and one short osmium-osmium bonds: Os(1)-Os(2) = 2.827 (1) Å, Os(l)-Os(3) = 2.828 (1) Å, Os(2)-Os(3) = 2.691 (1) Å. The isocyanide ligand resides in an equatorial coordination site on osmium Os(2). The hydrogen atoms were not observed but are believed to occupy bridging positions as in the parent carbonyl complex. © 1979, American Chemical Society. All rights reserved.