ELECTRON DENSITY DISTRIBUTION ON TWO IMINO COMPLEXES, [Co(C10H20N8)(H2O)2]+[ClO4]22- AND
[Cu(N2O2C16H14)]2. J. J. Lee, C. H. Hwang, G. H. Lee, Yu Wang*, Y. S. You, S. M. Peng, Department of Chemistry, National Taiwan University, Taipei, Taiwan
The crystal and molecular structures of [Co(C10H20N8)(H2O)2]+ [CIO4]2- and [Cu(N2O2C16H14)]2 have been determinated by single-crystal X-ray diffraction method at 295 and 125 K. The former crystallizes in the space group of P bca at 125 K with cell parameters a=11.655(2), b=16.930(4), c=10.508(2)Å, Mw=556.27, V=2073.4(6)Å3, Z=4. The molecular symmetry is Ci with the Co atom at the 1 position; the latter one crystallizes in the space group C 2/c with cell parameters a=26.609(2), b=6.9143(4), c=14.567(2)Å, Mw=559.68, V=2073.4(6)Å3, Z=4. The molecule is a dinuclear complex with molecular symmetry of Ci.
In the Co complex, the Co atom is coordinated by four imino N at the macrocyclic plane and two water molecules at the axial position. The Co-N distances are 1.9026(7)Å and 1.9153(7)A. The CoN4O2 can be described as a tetragonal distorted octahedron due to Jahn - Teller distortion. The ligand is a partially [[pi]]-delocalized [[alpha]]-diimine ligand, the C-N bond distance is 1.301(1)Å, indicating a double bond character, and the N-N bond is 1.373(1) and 1.382(1)Å, which is a single bond character. In the Cu complex, the Cu ion is five coordinated(N2O3) with one oxygen atom served as bridge between two Cu ions. The Cu-N distances are 1.9567(8) and 1.9596(8)Å. Electron density distribution based on multipole refinement confirms the predication on the asphericity in electron density around the metals. The bonding between imino nitrogen and metal ions(Co and Cu) can be recognized as a [[sigma]]-donor from N, the density depletion is found along the d[[sigma]] direction on both complexes. Electron density distribution on low spin d7 Co(II) and d9 Cu(II) will be displayed. Detail comparison between experimental and theoretical results will be presented for Co-complex. Strong covalent bond characters are found on ligand part in both complexes.