Very long C–H···O contacts can be weak hydrogen bonds: experimental evidence from crystalline [Cr(CO)3{η6-[7-exo-(CCH)C7H7]}]

Abstract

The crystal structure of the title compound contains a very long C–H···O contact from the ethynyl group to a carbonyl ligand with a H···O separation of 2.92 Å; weakly hydrogen bonding character of this contact is inferred from the Raman and the IR absorption spectra, showing the long range nature of the C–H···O hydrogen bond.