A mass spectrometric investigation of clusters formed by sodium cations and pentacyanonitrosylferrate(2−) anions in the gas phase, and an exploration of structures of some of the clusters using Density Functional Theory

► Mass spectrometric studies reveal more than 50 new aggregates of Na+ with [Fe(CN)5(NO)]2−. ► Aggregates have sizes up to nanomolecular [Na36{Fe(CN)5(NO)}20]4− and [Na47{Fe(CN)5(NO)}22]3+. ► DFT calculations show directional Na+:[Fe(CN)5(NO)]2− bonding involving only the cyano N atoms. ► Na+:[Fe(CN)5(NO)]2− bonding may cause significant angle bending in the [Fe(CN)5(NO)]2− anion. ► Terminal and bridging Na+ can coordinate up to three and six N atoms, respectively.