Oxidative addition of halogen across an Os-Os or Os-Sb bond: Formation of five-membered osmium-antimony carbonyl rings

• Formation of five-membered Os3Sb2 and 3,5-fused Os3Sb3 metallacyclic rings.
• Fourth isomer of the five-membered Os3Sb2 metallacyclic ring Os3(Cl)2(CO)10(μ-SbPh2)2.
• Formation of such rings via oxidative addition across an OsOs bond.
• Oxidative addition of halogen in 3,5-fused Os3Sb3 metallacyclic rings is across an OsSb bond.
• Two isomers of five-membered metallacycle containing a μ-I ligand.

Halogenation of the cluster Os3(CO)10(μ-SbPh2)2, 2, with PhICl2 or I2 affords the five-membered metallacyclic rings Os3(Cl)2(CO)10(μ-SbPh2)2, 3d and Os3(I)2(CO)10(μ-SbPh2)2, 3d-I, respectively, via oxidative addition across an OsOs bond. The reaction of 2 with SbPh2Cl or SbPh2H gives the 3,5-fused rings Os3(X)(CO)9(μ-SbPh2)3, (X = Cl, 4a; H, 4b), respectively. Halogenation of 4 with PhICl2 gives the five-membered metallacyclic rings Os3(Cl)(X)(CO)9(SbPh2Cl)(μ-SbPh2)2 (X = Cl, 5a; H, 5b) via oxidative addition across an OsSb bond. The analogous reaction with I2 also results in oxidative addition across an OsSb bond, but this is followed by displacement of SbPh2I to afford a five-membered metallacycle containing a μ-I ligand, viz., Os3(μ-I)(X)(CO)9(μ-SbPh2)2 (X = Cl, 7a, H, 7b).

Figure optionsDownload as PowerPoint slide