Experimental Identification of the Active Site in the Heteronuclear Redox Couples [AlVO ] /CO/N O (x=3, 4) by Gas-Phase IR Spectroscopy.

Cryogenic ion vibrational spectroscopy was used in combination with electronic structure calculations to identify the active site in the oxygen atom transfer reaction [AlVO ] +CO→[AlVO ] +CO . Infrared photodissociation spectra of messenger-tagged heteronuclear clusters demonstrate that in contrast to [AlVO ] , [AlVO ] is devoid of a terminal Al-O unit while the terminal V=O group remains intact. Thus it is the Al-O moiety that forms the active site in the [AlVO ] /CO/N O (x=3, 4) redox couples, which is in line with theoretical predictions.