Preparation of [C,N,O]-Pincer Osmium Complexes by Alkylidene Metathesis with a Methyl Group of 2,6-Diacetylpyridine

The complex [(η6-p-cymene)OsCl(CHPh)(IPr)]OTf
(1) reacts with 2,6-diacetylpyridine in acetonitrile at 40 °C to
give the [C,N,O]-pincer derivative [OsCl{κ3C,N,O-[CHC(O)pyC(CH3)O]}(NCCH3)(IPr)]OTf (2), containing an alkylidene
function at the terdentate ligand. Under the same conditions in
dichloromethane, the neutral species OsCl(OTf){κ3C,N,O-[CHC(O)pyC(CH3)O]}(IPr) (3) is formed.