ISOCYANIDE INSERTION REACTIONS AND THEIR ROLE IN THE CLUSTER-CATALYZED HYDROGENATION OF ISOCYANIDE MOLECULES

Studies of the reactions of H2Os3(CO)10 with the isocyanide molecules, CNR, R = C6H5, CH3, t-C4H9, are reported. The initial products are 1:1 adducts of the type H(μ-H)Os3(CO)10CNR. A hydrogen atom can be transferred to the isocyanide ligand in two different ways depending on the reaction conditions. In strong donor solvents compounds of the type (μ-H)(μ-C═N(H)R)Os3(CO)io are obtained apparently through a proton dissociation and readdition process. When heated in weak donor solvents a hydrogen atom is transferred to the carbon atom. This evidently occurs through an intramolecular insertion type process. The initial products, (μ-H)(μ-η2-HC═NR)Os3(CO)10, R = C6H5, CH3, contain a formimidoyl ligand bridging the edge of the cluster. With further heating these compounds lose CO, reversibly, to form the complexes (μ-H)(μ3-η2-HC=NR)Os3(CO)9, R = C6H5, CH3, in which the formimidoyl ligand is bonded to the face of the cluster. An X-ray crystallographic analysis of the compound (μ-H)(μ3-η2-HC=NC6H5)Os3(CO)9 is reported. This compound reacts with P(OCH3)3 to form the adduct (formula omitted) which contains an edge-bridging formimidoyl ligand. An X-ray crystallographic analysis of this compound is also reported. From the reaction solutions which have produced the formimidoyl-containing products, the compounds (μ-H)2Os3(CO)9(CNR), R = C6H5, CH3, t-C4H9), have been isolated. The possible role of these compounds in the formation of the formimidoyl-containing products is discussed. © 1979, American Chemical Society. All rights reserved.