Ligand substitution in the osmium-antimony rings Os3(μ-SbPh2)2 (CO)10 and Os3(μ-SbPh2)3(Cl)(CO)9

TMNO-activated ligand substitution in the fused ring compounds Os-3(mu-SbPh2)(2)(CO)(10), 1, and Os-3(mu-SbPh2)(3)(Cl)(CO)(9), 2, in acetonitrile affords the mono-and disubstituted CH3CN-derivatives. The initial product of CH3CN substitution in 1 is an equatorial isomer, which can isomerize to the axial isomer upon heating; they are the first examples in which both isomers have been characterized crystallographically. Subsequent reaction of the CH3CN-derivatives of 2 with two-electron donor ligands L do not always result in the displacement of the acetonitrile ligands; displacement of a carbonyl ligand can also occur and appears to depend on the stereoelectronic properties of L. This is suggestive of an associative mechanism. (C) 2016 Elsevier B.V. All rights reserved.