Attaching Metal-Capped sp Carbon Chains to Metal Clusters: Synthesis, Structure, and Reactivity of Rhenium/Triosmium Complexes of Formula [(η5-C5Me5)Re(NO)(PPh3)(CC)nOs3(CO)y(X)z]m+, Including Carbon Geometries More Distorted than Planar Tetracoordinate
✍ Scribed by Stephen B. Falloon; Slawomir Szafert; Atta M. Arif; J. A. Gladysz
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 280 KB
- Volume
- 4
- Category
- Article
- ISSN
- 0947-6539
No coin nor oath required. For personal study only.
✦ Synopsis
Reaction of [(h 5 -C 5 Me 5 )Re-(NO)(PPh 3 )(CCH)] (1) and [Os 3 -(CO) 10 (NCCH 3 ) 2 ] (CH 2 Cl 2 , room temperature) gives the ReC 2 Os 3 complex [(h 5 -C 5 Me 5 )Re(NO)(PPh 3 )(CC)Os 3 -(CO) 10 (H)] (2, 78 %). The crystal structure shows that the hydride and ReCC terminus bridge the same two osmium atoms symmetrically. The Re ± C and ReC ± C bond lengths, and IR and NMR properties, indicate contributions by both ReCC(Os 3 ) and ReCC(Os 3 ) À resonance forms. Analogous ReC 4 Os 3 (4, 83 %) and Re-C 6 Os 3 (6, 61 %) complexes are prepared similarly, and are increasingly less stable in solution and the solid state. Cyclic voltammograms of 2, 4, and 6 show partially reversible oxidations. Complex 4 decarbonylates in refluxing hexane to give [(h 5 -C 5 Me 5 )Re(NO)(PPh 3 )(CCC-C)Os 3 (CO) 9 (H)] (7, 57 %), in which the ReCCCC terminus binds to three osmium atoms, and the adjacent carbon (and hydride) to two. Reaction of 2 and HBF 4 ´Et 2 O gives [(h 5 -C 5 Me 5 )Re(NO)-(PPh 3 )(CC)Os 3 (CO) 10 (H) 2 ] ´BF À 4 (8 BF À
4 , 69 %). The crystal structure of the SbF À 6 salt shows an ReC 2 Os 3 unit very similar to that of 2, but with the hydrides bridging different osmium ± osmium bonds. The C 3 OMe complex [(h 5 -C 5 Me 5 )Re(NO)(PPh 3 )(CCC(OMe))-Os 3 (CO) 11 ] (9) decarbonylates in refluxing heptane to give [(h 5 -C 5 Me 5 )Re-(NO)(PPh 3 )(CCC)Os 3 (CO) 9 (OMe)] (10, 63 %), in which the ReCCC terminus binds to three osmium atoms, and the center carbon binds to the osmium that is not methoxide-bridged. The crystal structure shows the ReCCC carbon to be highly distorted, binding to four atoms that fall on one side of a plane through the carbon.