The electronic structure and the solid state properties of the one-dimensional tetraza porphin nickel (II ) system. A self-consistent-field Hartree-Fock crystal-orbital approach based on a semiempirical Hamiltonian

Abstract

The electronic structure and the solid state properties of tetraza porphin nickel (II), 1, have been studied by means of self-consistent field (SCF) Hartree-Fock (HF) crystal-orbital (CO) calculations that are derived in the framework of a semiempirical INDO Hamiltonian. The iterative SCF procedure is based on an algorithm where Hartree damping of the bond-order matrices and a direct steepest-descent formalism have been combined in order to avoid SCF difficulties in the CO method as a result of the closely spaced occupied and virtual Fermi seas. The diatomic intercell energies are mainly determined by electrostatic contributions. The NiNi coupling is highly repulsive, large stabilising two-centre pairs are found for the interaction between the 3d centre of the reference cell and the heteroatoms (N) in the neighbouring fragments. A large number of ligand, pi , lone-pair and sigma bands are predicted to be on top of dispersion curves with substantial Ni3d character. Oxidation processes in 1 are ligand-centred leading to organic pi radical cations. The INDO CO results for 1 are compared with experimental data derived for nickel phthalocyanine, NiPc, and halogenated NiPc derivatives.