title: The crucial role of polyatomic anions in molecular architecture: structural and magnetic versatility of five nickel(II) complexes derived from A N,N,O-donor Schiff base ligand.
abstract: Five new nickel(II) complexes [Ni(2)L(2)(N(3))(2)(H(2)O)(2)] (1), [Ni(2)L(2)(NO(3))(2)] (2), [Ni(2)L(2)(O(2)CPh)(CH(3)OH)(2)]ClO(4).0.5CH(3)OH (3), [Ni(3)L(2)(O(2)CPh)(4)] (4), and [Ni(2)L(2)(NO(2))(2)](n) (5) have been synthesized by using a tridentate Schiff base ligand, HL (2-[(3-Methylamino-propylimino)-methyl]-phenol), and the polyatomic monoanions N(3)(-), NO(3)(-), PhCOO(-), or NO(2)(-). The complexes have been structurally and magnetically characterized. The structural analysis reveals that in all five complexes, the Ni(II) ions possess a distorted octahedral geometry. Complexes 1 and 2 are dinuclear with di-mu-1,1-azido and di-mu(2)-phenoxo bridges, respectively. Complex 3 is also a di-mu(2)-phenoxo-bridged dinuclear Ni(II) complex but has an additional syn-syn benzoate bridge. Compound 4 possesses a linear trinuclear structure with the tridentate Schiff base ligand coordinated to the terminal nickel atoms which are linked to the central Ni(II) by phenoxo and carboxylate bridges. Complex 5 consists of a dinuclear entity, bridged by di-mu(2)-phenoxo together with a cis-(mu-nitrito-1kappaO:2kappaN) nitrite ion. The dinuclear units are linked each other by another bridging trans-(mu-nitrito-1kappaO:2kappaN) nitrite to form a Ni(II) chain that shows the presence of unprecedented alternating cis- and trans-N,O bridging mode of the nitrite anion. Variable-temperature magnetic susceptibility measurements of complex 1 indicate the presence of ferromagnetic exchange interactions within the dimer (J = 23.5(3) cm(-1)) together with antiferromagnetic interdimer interactions (J' = -0.513(3) cm(-1)), whereas compounds 2 and 3 show intradimer antiferromagnetic interactions (J = -24.27(6) and -16.48(4) cm(-1), respectively). Ferromagnetic coupling (J = 6.14(2) cm(-1)) is observed in complex 4 for the linear centro-symmetric Ni(II) trimer, whereas complex 5 shows an alternating intra-chain antiferromagnetic coupling (J(1) = -32.1(1) cm(-1) and J(2) = -3.2(1) cm(-1)).
authors.affiliation: Department of Chemistry, University College of Science, University of Calcutta, 92 APC Road, Kolkata-700 009, India.
authors.forename: Pampa
authors.initials: P
authors.lastname: Mukherjee
authors.forename: Michael G B
authors.initials: MG
authors.lastname: Drew
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Gómez-García
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Ghosh
mesh_terms: D000838:Anions; D018360:Crystallography, X-Ray; D008024:Ligands; D008280:Magnetics; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D012545:Schiff Bases / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: D000838:Anions; D008024:Ligands; D012545:Schiff Bases; D009532:Nickel