Theoretical studies examining a series of binuclear transition metal pentazolides Rh-2(N-5)(4) predict paddle wheel type structures with very short metal-metal distances. Natural bonding orbital analysis indicated that the bonding between the metal atom and the five-membered ring is predominantly ionic for Rh-2(N-5)(4) species, and a high-order metal-metal multiple bonding exists between the two metal atoms. In addition, the presence of the delocalized pi orbital plays an important role in the stabilization of Rh-2(N-5)(4). Nucleus independent chemical shift values confirm that the planar N-5 exhibits aromaticity. The dissociation energies into mononuclear fragments are predicted for Rh-2(N-5)(4). (C) 2015 Elsevier B.V. All rights reserved.