Osmium reaction with isonitriles

The osmium hydride (CO)ioOs3H2 reacts with isonitriles to give monosubstituted products (CO)io(RNC)Os3H(/2-H), which react further via insertion to give (CO)io(ju-ri -RNCH))(/i-H)Os3. In weak donor solvents, hydride attacks at the carbon whereas strong donor solvents result in hydride attack at nitrogen. The latter reaction results from deprotonation of the hydride complex, followed by reprotonation at nitrogen. 

Isonitriles are isoelectronic with carbon monoxide bnt homoleptic see Homoleptic Compound) isonitrile complexes are more difficnlt to prepare than carbonyl complexes. The reduction of OsXg with ethanol in the presence of methylisonitrile gives OsX2(CNMe)4. The osmium(II) isonitrile complex [Os(CNMe)6] + results from the alkylation of [Os(CN)6]" with MeOS02CF3. More generally, [Os(CNR)6] + can be prepared by reaction of 0s2(02CMe)4Cl2 with alkyl isonitriles. 

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