An ab initio study on coinage atom-inserted cyanide/isocyanide: XMCN/XMNC (M = coinage atoms; X = halogen)

The coinage atom-inserted cyanide/isocyanide compounds, XMCN and XMNC (X = halogens) formed by the insertion of a coinage atom into the X-C(N) bonds of XCN (or XNC), were investigated by ab initio methods. XMCN was predicted to be more stable than XMNC, which is different from the case of XUCN/XUNC reported previously. Based on the analyses on the ionization dissociation pathways, the M-C (or M-N) bond is more easily broken than the X-M bond. Moreover, the order of the M-C (or M-N) bond energy in XMCN (or XMNC) is XAuCN (XAuNC) > XCuCN (XCuNC) > XAgCN (XAgNC). The shift characters of v _C-N in XMCN (or XMNC) with respect to the concerning precursor can be used to identified XMCN and XMNC experimentally. The results of charge decomposition analysis (CDA) and atoms-in-molecule (AIM) illustrate that the X-M and M-C(N) bond behaves as a coordination bond, while the C-N bond is a typical polar covalent bond. The higher thermodynamic stability of XMCN is the result of the -CN group having better coordination ability than the -NC group.