Synthesis, structure, electrochemistry, and magnetic properties of face-sharing bioctahedral nickel complexes containing a N3Ni(μ-S2)(μ-X)NiN3 core (X = F-, Cl-, Br-, OH-)

A series of isostructural dinickel complexes of the type [Ni-2(L-Me2H4)][X](2) (where (L-Me2H4)(2-) represents a 28-membered macrocyclic N6S2 donor ligand, X = ClO4- (1a), I- (1b)) and [Ni-2(L-Me2H4)(mu-L')][X] (X = ClO4-, L' = F- (2a), Cl- (3a), OH- (5a), N-3(-) (6a), X = BPh4-, L' = F- (2b), Cl- (3b), OH- (5b), N-3(-) (6b), X = Br-, L' = Br- (4)) have been synthesized and characterized by IR, ESI-MS, UV-vis, cyclic voltammetry, SQUID magnetometry, and X-ray crystallography. The dications in 1a and 1b feature an edge sharing bis(square-pyramidal) N3Ni(mu-S-2)NiN3 core, while the monocations of 2a-6b comprise a face-sharing bioctahedral N3Ni(mu-S)(2)(mu-L')NiN3 core. The variation of the coordination geometry has a strong impact on the magnetic properties of the Ni complexes. 3a, 4, and 5a have an S = 2 ground state with a value for the magnetic exchange coupling constant J of +10.06 cm(-1), (3a), J = +12.13 cm(-1) (4) and J = +2.9(1) cm(-1) (5a), while 1a, 1b, and 2a have an S = 0 ground state with J = -13.4 cm(-1) (1a), -22.8 cm(-1) (1b) and J = -0.56 cm(-1) (2a) (H = - 2JS(1)S(2)). Broken symmetry density functional theory calculations have been performed to study the individual contributions of the coligand and thiolato-bridges to the overall magnetic behavior. The capability to propagate exchange interactions was found to increase in the order Br- < Cr- < N-3(-) < OH- similar to F-. (C) 2016 Elsevier B.V. All rights reserved.