Al(CN) 3−6 and Al(NC) 3−6 trianions

Abstract

At this time the smallest trianions observed in the gas phase are fluorinated fullerenes and large organic ring systems with attached sulfonic acid groups. Considerably smaller trianions have been predicted to be sufficiently stable for observation in mass spectrometers, but have not yet been detected. Here two isomers of the aluminium cyanide trianion, Al(CN)³⁻₆ and Al(NC)³⁻₆, are studied using ab initio methods. These two isomers are predicted to be electronically stable and to show substantial barriers with respect to dissociation of CN⁻ units. Thus, the investigated trianions hit a sweat-spot regarding the possibility of detection, as they are by far more robust with respect to dissociation than alkali halide trianions, while at the same time materials from which these trianions can at least in principle be formed are much more readily available than those needed for producing small covalently bound trianions.