Extreme Oxatriquinanes: Structural Characterization of alpha-Oxyoxonium Species with Extraordinarily Long Carbon-Oxygen Bonds

Günbaş, Emrullah Görkem
Sheppard, William L.
Fettinger, James C.
Olmstead, Marilyn M.
The first stable alpha-oxyoxonium species have been synthesized and characterized. Strong donation of nonbonding electrons on oxygen into the adjacent sigma*(C-O+) orbital was predicted by modeling to result in unheard of carbon-oxygen bond lengths. The kinetic stability of the triquinane ring system provides a platform upon which to study these otherwise elusive species, which are evocative of intermediates on the acetalization reaction pathway. Crystallographic analysis of the alpha-hydroxy and alpha-methoxy oxatriquinane triflates reveals 1.658 and 1.619 angstrom C-O+ bond lengths, respectively, the former of which is a new record for the C-O bond.