ELECTROCHEMICAL AND STRUCTURAL STUDIES OF NICKEL(II) COMPLEXES WITH N2O2 SCHIFF-BASE LIGANDS .2. CRYSTAL AND MOLECULAR-STRUCTURE OF N,N'-1,2-ETHANE-1,2-DIYL-BIS(2-HYDROXYACETOPHENONYLIDENEIMINATE)NICKEL(II), N,N'-1,2-CIS-CYCLOHEXANE-1,2-DIYL-BIS(2-HYDROXYACETOPHENONYLIDENEIMINATE)-NICKEL(II) AND N,N'-1,2-BENZENE-1,2-DIYL-BIS(3,5-DICHLOROSALICYLIDENEIMINATE)NICKEL(II)

• Type: Article in International Scientific Journal
• Date: 1994

Authors

AZEVEDO, F (Author) Other; CARRONDO, MAAFD (Author) Other; DECASTRO, B (Author) FCUP; CONVERY, M (Author) Other; DOMINGUES, D (Author) Other; FREIRE, C (Author) FCUP; DUARTE, MT (Author) Other; NIELSEN, K (Author) Other; SANTOS, IC (Author) Other

Journal

Title: Inorganica Chimica Acta

Vol. 219

Pages: 43-54

ISSN: 0020-1693

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 82 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-001-K40

DOI: 10.1016/0020-1693(94)03821-x

Abstract (EN): Reductive and oxidative chemistry of three complexes of formula [Ni(L)], where L represents a N2O2 Schiff base pseudomacrocyclic ligand based on salicylaldehyde derivatives and three different diamines, was studied in (CH3)2SO: NN'-1,2-ethane-1,2-diyl-bis(2-hydroxyacetophenonylideneiminate)nicke](II) (1); NN'-1,2-cis-cyclo-hexane-1,2-diyl-bis(2-hydroxyacetophenonylideneiminate)nickel(II) (2); NN'-1,2-benzene-1,2-diyl-(bis(3,5-dichlo-rosalicylideneiminate)nickel(II) (3). Electrochemical behavior of the complexes was determined by cyclic voltammetry, and EPR spectroscopy was used to characterize the one-electron reduced/oxidized species. Reduction of the complexes 1 and 2 yielded Ni(I) complexes with a d(xy) ground state (g(z)>g(x),g(y)), but the reduction of 3 is ligand-centered as suggested from the pseudo-isotropic radicalar EPR signal of frozen electrolyzed solutions. Oxidation of all three complexes is metal-centered and the oxidized products are low spin hexacoordinate Ni(III) species with two solvent molecules coordinated axially, with a d(z2) ground state (g(x),g(y)>g(z)). The crystal structures of the three Ni(II) complexes were determined from single crystal X-ray diffraction data collected with the use of Mo Kalpha radiation. 1: space group C2/c with a=25.963(3), b=7.2973(4), c=17.357(2) angstrom, beta = 107.085(5)-degrees, Z=8 (R=0.061); 2: space group P2(1)/a with a=9.645 (6), b=19.149(16), c=10.743(5) angstrom, beta=94.66(2)-degrees, Z=4 (R=0.085); 3: space group P2(1)/n with a=13.372(5), b=8.785(2), c=16.534(5) angstrom, beta=101.60(3)-degrees, Z=4 (R=0.054). Crystal packing of 1 and 3 involves the pairing of two centrosymmetrical related molecules in dimers, but that of 2 shows no systematic parallel orientation of any part of the molecules. X-ray structural data have provided a rationale for the E1/2 values obtained for the reduction and oxidation processes.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12