Two new μ2-(1,1-azido) and μ2-(1,1-phenoxido)-bridged dinuclear nickel(II) complexes: Syntheses, single-crystal structures and magnetic studies

Abstract

Two dinuclear azido bridged Ni(II) complexes [Ni2(HL1)2(N3)(C8H7O3)]·(H2O) (1) and [Ni2(L2)2(N3)2(H2O)](2) [H2L1 and HL2 are Schiff bases, obtained from the condensation of 2-hydroxy-3-methoxy-benzaldehyde with 2-amino-2-methyl-1-propanol and N,N-diethylethylene diamine, respectively; C8H7O3 = 3-methoxy-2-oxo-benzaldehyde] have been synthesized and their crystal structures have been determined. Complex 1, C32H39N5Ni2O10, crystallizes in a triclinic system, space group P-1 with a = 10.0846 (6), b = 12.5179 (7), c = 14.1176 (8) Å, α = 74.3873 (7), β = 83.9553 (7), γ = 83.1921 (7) º and Z = 2; complex 2, C28H44N10Ni2O5, crystallizes in an orthorhombic system, space group Pbca with a = 12.4197 (1), b = 21.4737 (4), c = 24.4569 (5) Å, and Z = 8. X-ray single crystal structure determination reveals that both the complexes are dinuclear with μ2-(1,1-azido) and μ2-(penoxido) bridges. Variable temperature magnetic studies indicate overall ferromagnetic interaction between nickel (II) centers in both the complexes. The experimental magnetic data of the complexes were fitted using PHI program and the Ĥ = - JŜ1Ŝ2 - D (Ŝ1z2 + Ŝ2z2) - gβH (Ŝ1 + Ŝ2) Hamiltonian, where S1 = S2 = SNi, J is the intramolecular magnetic exchange constant and D is the zero-field splitting parameter. An intermolecular interaction term (zJ′) was also considered in the model and a good agreement between experimental and simulated curves was found by using the following parameters: gNi = 2.13, DNi = 5.83 cm−1, JNi-Ni = 14.61 cm−1 and zJ’ = −0.1 cm−1 for 1, and gNi = 2.15, DNi = 2.33 cm−1, JNi-Ni = 13.09 cm−1and zJ’ = −0.07 cm−1 for 2.