The valence electron distribution in (5,10,15,20-tetramethylporphyrinato)nickel(II), Ni(TMP), has been investigated by experimental and theoretical techniques. An extensive ((sin θ)/λ < 1.0 Å-1), low-temperature (140 K) set of crystallographic data has been analyzed by the (X- XHo) method in order to extract experimental deformation densities. In addition, model deformation densities have been mapped after a least-squares refinement of deformation functions with the use of a multipole model. First-principles molecular calculations on Ni(TMP), the unsubstituted (porphyrinato)nickel(II), Ni(P), and a model of Ni(TMP) perturbed by neighboring molecules were carried out with the use of the self-consistent local density model. One-electron energy levels, wave functions, and charge densities were obtained from the discrete variational method in an LCAO basis. The experimental and theoretical deformation maps show features qualitatively in agreement. The theoretical effects of the perturbing neighboring molecules show some interesting charge density shifts, but are probably too small to account conclusively for the observed difference in Ni-N bond lengths of 0.020 (1) Å (conventional refinement). A distorted molecule calculation does, however, reproduce essential features of the experimental density distribution.
ASJC Scopus subject areas
- Colloid and Surface Chemistry