A small and stable covalently bound trianion

Stable doubly charged anions have become well known over the past decade, but the knowledge about higher-charged molecules is still sparse. Especially the minimum size of a covalently bound trianion which is still stable is an open question. Here, we present the smallest trianion of this kind known up to now, namely, B(C(2)CO(2))(3) (3-). After establishing its geometrical parameters, we investigate its stability with respect to electron autodetachment and fragmentation of the molecular framework. Our results lend strong support to the notion that this trianion indeed represents a stable compound which should be observable in the gas phase.