Linear Ni(I) Complex in cis-[Ni(CN)_4Cl_2]~(5-) Cluster

摘要

Ab initio embedded cluster UMP2 calculations are performed on paramagnetic 3d~9 cis-[Ni(CN)_4Cl_2]~(5-) cluster in KCl host lattice taking into account short and long-range crystal interactions. The results confirm the d_(x~2-y~2) unpaired electron orbital assignment, with a small participation of p_x and p_y basis functions. Hyperfine interactions are shown to arise mainly from spin polarization of their valence orbitals caused by the unpaired electron. The calculated difference between the two possible Ni-CN distances is 0.25 A. Chlorine ions, first neighbors to the central metallic atom, as well as the two cyanides pointing to the d_(x~2-y~2) orbital, are found to be not coordinated to the metal. The coordination complex present in the cis-[Ni(CN)_4Cl_2]~(5-) cluster is thus assigned to linear [Ni(CN)_2]~- instead of hexacoordinated or planar forms.