Azido and thiocyanato bridged dinuclear Ni(II) complexes involving 8-aminoquinoline based Schiff base as blocking ligands: Crystal structures, ferromagnetic properties and magneto-structural correlations

Abstract

The use of two 8-aminoquinoline-based tridentate N3-donor rigid Schiff base ligands (L1 and L2) with Ni(II) in the presence of the pseudohalides, NaN3 and NaSCN results in the crystallization of the two novel Ni(II) dimers: [Ni2(L1)2(µ1,1′-N3)2(N3)2] (1) and [Ni2(L2)2(µ1,3-NCS)2(NCS)2] (2). Both complexes are centrosymmetric Ni(II) dimers where the Schiff base ligands coordinate the octahedral Ni(II) centres in a mer configuration with one terminal and two bridging pseudohalide ligands in the remaining positions. Complex 1 shows Ni(II) ions connected by a double µ1,1′-N3− bridge whereas in complex 2 the Ni(II) ions are connected by a double µ1,3-NCS− bridge. The magnetic properties show the presence of a weak ferromagnetic coupling in both compounds that can be fit with g = 2.290(6), J = 6.1(2) cm−1, zJ′ = −0.32(1) cm−1 and |D| = 4.34(5) cm−1 for 1 and g = 2.096(2), J = 4.71(5) cm−1, zJ′ = −0.054(2) cm−1 and |D| = 1.52(2) cm−1 for 2 (the Hamiltonian is written as −2JS1S2). Both J values have been rationalized in terms of previous magneto structural correlations based on the Ni-N-Ni bridging angle in 1 and on the asymmetry of the Ni-S-C-N-Ni bridges in 2.