Quantum chemical calculations suggest that inverse sandwich compounds with the general formula MN7M′, where M is an alkali metal (K,Rb,Cs), N7 is a ten-π-electron ring, and M′ is an alkaline-earth metal (Ca,Sr,Ba), are local C7v; minima. Among these systems, the CsN7Ba molecule is the stablest of all and presents a barrier of 35 kcal/mol to dissociation towards CsNBa and three N2 molecules. Substantial 5d character is found in the bonding. Possible ways of making these high-energy compounds are discussed.
- Honorary d elements B3LYP