Abstract
The dinuclear mesitylene osmium complexes [(Mes) 2Os 2(μ-H) 3]X ( 2a, b) and [(Mes)OsH(μ-H)] 2 ( 3) are prepared from [(Mes)OsCl 2] n ( 1) and NaBH 4. The complex 2a (X = Cl) and its corresponding BF 4 salt 2c can also be obtained from the reaction of 3 with HCl or HBF 4, respectively. The structures of 2a and 3 have been determined by single-crystal X-ray diffraction studies. The cation of 2a contains two equivalent (Mes)Os fragments linked by a rather short OsOs bond (247.41(2) pm) and three bridging hydride ligands. The midpoints of the six-membered rings together with the two osmium atoms form a linear unit. The metal—metal distance in compound 3 (267.34(6) pm) is significantly longer than that in the cation of 2a and corresponds to an OsOs double bond. The trans arrangement of the mesitylene rings with regard to the metal—metal bond axis indicates that two of the hydride ligands in 3 are terminal and two are bridging. An equilibrium between the cis and trans isomers of 3 probably exists in CD 2Cl 2 solution. Treatment of [(Mes)OsCl 2(PMe 3)] ( 4) with NaBH 4 or LiAlH 4 affords the dihydrido complex [(Mes)OsH 2(PMe 3)] ( 5) which is also one of the products of the reaction of 3 with PMe 3. Compound 5 is photoreactive and on UV irradiation in benzene gives the hydrido phenyl complex [(Mes)OsH(C 6H 5)PMe 3].
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have