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.