Two polymeric linear tri-nickel(II) complexes:: [Ni3 (μ3-dpa)4(C4O4Me)]n(BF4)n and [Ni3(μ3-dpa)4(N3)]n(PF6)n synthesis, structural characterization and magnetic properties

Two new linear tri-nickel(II) complexes with an infinite polymeric chain, [Ni-3(mu(3)-dpa)(4)(C4O4Me)](BF4)1 and [Ni-3(mu(3)-dpa)(4)(N-3)](PF6) 2, [dpa(-) = di(alpha-pyridyl)amido anion], have been synthesized and their structures were determined by X-ray diffraction. Compound 1 crystallizes in the monoclinic system, space group C 2/c, with a = 19.9078(3), b = 13.2986(2), c = 37.6622(5) (A) over circle, beta = 94.091 (1)degrees, Z = 8. Compound 2 crystallizes in the monoclinic system, space group P 2(l)/n, with a = 13.323(4), b = 23.217(3), c = 17.528(5) (A) over circle, beta = 94.42(3)degrees, Z = 4. The two complexes are described as one-dimensional systems with the (C4O4Me)(-), 1, or N-3(-), 2, serving as a mu-(1,3) bridged ligand at the two axial sites of each [Ni-3(mu(3)-dpa)(4)](2+) fragment. The Ni-Ni distances of 2.400(1) and 2.402( 1) in 1 and 2.389(2), 2.385(2) in 2 are obviously shorter than those of 2.4325(7), 2.4356(7) in the monomeric complex [Ni-3(mu(3)-dpa)(4)(N-3)(2)] 3. The magnetic properties of complexes 2 and 3 were studied by susceptibility measurements vs temperature. The X-m vs T plots of both complexes show a strong anti-ferromagnetic behavior. The simulated J(13) values are -95 cm(-1) and -97 cm(-1) for 2 and 3, respectively.