Sequential bond energies and structures of the Cr + ⋅(N 2 ) n , n =1 −4

Abstract

DFT calculations, with an effective core potential for the chromium ion and large polarized basis set functions have been used to calculate the sequential bond dissociation energies of the Cr+⋅(N2)n (n = 1—4) complexes. A linear configuration was obtained for the Cr\(^{+}\cdot \textit {N}_{2}\) and Cr+⋅(N2)2 complexes with sequential bond dissociation energies of 14.6 and 16.4 kcal mol−1, respectively. For the Cr+⋅(N2)3 and Cr+⋅(N2)4 complexes, distorted trigonal pyramidal and tetrahedral geometries were optimized with sequential bond dissociation energies of 6.5 and 5.5 kcal mol−1, respectively. π- back-donation in side-on approach of the Cr\(^{+}\cdot \textit {N}_{2}\) leads to the formation of a tilted structure with the Cr+ ion in central position. The di-ligated complex exhibits the strongest bond dissociation energy among these four Cr+⋅(N2)n (n = 1—4) complexes since it has the largest Cr+—N bond order. End-on structures and sequential bond dissociation energies of the Cr+·(N2)1-4 were studied using different DFT methods. The interaction in these complexes is of physical nature, where the di-ligated complex has the largest BDE. For tilted structure, [N·Cr·N]+, the interaction involves an electronic transfer from Cr+ to N (π-back donation).