Luminescence of the oxonium ions image with ML = AuIPPh3 and HgIICl

The oxonium ions image and image are phosphorescent at r.t. and 77 K, respectively. It is suggested that these ions which are characterized by a rather flat trigonal pyramid in the ground state undergo a distortion to a steeper pyramid in their phosphorescent states. This structural change is caused by metal–metal bonding in the excited state.