Electrochemical and structural studies of nickel(II) complexes with N2O2 Schiff base ligands 2. Crystal and molecular structure of...

• Tipo: Artigo em Revista Científica Internacional
• Data: 1994

Autores

Azevedo, F (Autor) Outra; Carrondo, MAAFdCT (Autor) Outra; de Castro, B (Autor) FCUP; Convery, M (Autor) Outra; Domingues, D (Autor) Outra; Freire, C (Autor) FCUP; Duarte, MT (Autor) Outra; Nielsen, K (Autor) Outra; Santos, IC (Autor) Outra

Revista

Título: Inorganica Chimica Acta

Vol. 219

Páginas: 43-54

ISSN: 0020-1693

Editora: Elsevier

Indexação

ISI Web of Knowledge

Scopus - 78 Citações

Outras Informações

ID Authenticus: P-007-AYY

Abstract (EN): Title full: Electrochemical and structural studies of nickel(II) complexes with N2O2 Schiff base ligands 2. Crystal and molecular structure of N,N¿-l,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)nick el(II). 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: N,N¿-1,2-ethane-1,2-diyl-bis(2-hydroxyacetophenonylideneiminate)ni ckel(II) (1); N,N¿-1,2-cis-cyclohexane-1,2-diyl-bis(2-hydroxyacetophenonylidenei minate)nickel(II) (2); N,N¿-1,2-benzene-1,2-diyl-(bis(3,5-dichlorosalicylideneiminate)nic kel(II) (3). Electrochemical behavior of the complexes was determined by cyclic voltametry, 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 dxy ground state (gz>gx, gy), 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 dz2 ground state (gx, gy>gz). The crystal structures of the three Ni(II) complexes were determined from single crystal X-ray diffraction data collected with the use of Mo K¿ radiation. 1: space group C2/c with a = 25.963(3), b = 7.2973(4), c = 17.357(2) Å, ß = 107.085(5)°, Z = 8 (R = 0.061); 2: space group P21/a with a = 9.645(6), b = 19.149(16), c = 10.743(5) Å, ß = 94.66(2)°, Z = 4 (R = 0.085); 3: space group P21/n with a = 13.372(5), b = 8.785(2), c = 16.534(5) Å, ß = 101.60(3)°, 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. © 1994.

Idioma: Inglês

Tipo (Avaliação Docente): Científica