C–H Activation of 3,3-diphenylcyclopropene in the reaction with Os(CO)2(PPh3)3: 3,3-diphenylcyclopropenyl, 2,2-diphenylcyclopropyl, and 3-phenylindenyl complexes of osmium(II)

Reaction between Os(CO)2(PPh3)3 and 3,3-diphenylcyclopropene under quartz–halogen irradiation leads to C(sp2)–H bond activation and the formation of the 3,3-diphenylcyclopropenyl complex, OsH[C3H(Ph-2)2](CO)2(PPh3)2 (1). When complex 1 is heated there is ring-opening of the cyclopropene ring and rearrangement to the 3-phenylindenyl complex, OsH[C9H6(Ph-3)](CO)2(PPh3)2 (2). Compound 1 reacts with HCl forming the 2,2-diphenylcyclopropyl complex, OsCl[C3H3(Ph-2)2](CO)2(PPh3)2 (3). Reaction of either 1 or 3 with excess HCl leads to reversible formation of the hydroxycarbene complex, OsCl2[C(OH)C3H3(Ph-2)2](CO)(PPh3)2 (4), through protonation of the acyl group formed by a migratory insertion reaction involving a carbonyl ligand and the σ-bound 2,2-diphenylcyclopropanyl ligand. An X-ray crystal structure determination of 2 is reported.

In a new pathway for the reaction of 3,3-diphenylcyclopropene with low-valent metal complexes, the reaction with Os(CO)2(PPh3)3 leads to a C–H activation process giving the 3,3-diphenylcyclopropenyl complex, OsH[C3H(Ph-2)2](CO)2(PPh3)2. This complex is thermally unstable and readily rearranges to the 3-phenylindenyl complex, OsH[C9H6(Ph-3)](CO)2(PPh3)2.Figure optionsDownload as PowerPoint slide