Synthesis, structure, magnetic property and self-assembly of two double end-on azide bridged ferromagnetic nickel(II) complexes with distinct bidentate blocking ligands: A combined experimental and theoretical study

Two centrosymmetric dinuclear nickel(II) complexes, [Ni-2(dmpn)(2)(hap)(2)(mu(1,1)-N-3)(2)] and [Ni-2(dmpn)(2)(hap)(2)(mu(1,1)-N-3)(2)], (dmpn=N,N-dimethyl-1,3-diaminopropane and Hhap = 2-hydroxyacetophenone, Hhan = 1-hydroxy-2-acetonaphthone) have been synthesized and characterized. Single crystal X-ray diffraction analyses confirm the structures of one of the tridentate Schiff bases used and both complexes. Variable temperature (1.8-300 K) magnetic susceptibility measurements indicate the presence of ferromagnetic coupling interactions among nickel(II) centers with J = 29(1) cm(-1) (in 1) and 15.62(2) cm(-1) (in 2). Calculated J values (37 cm(-1) in 1 and 31 cm(-1) in 2, respectively) are in agreement with the values obtained experimentally. C-H/pi interactions form supramolecular chains both in 1 and 2. DFT calculations reveal that C-H/pi interaction energies are large negative (Delta E-1 = -12.9 kcal/mol for 1 and Delta E-2 = -17.2 kcal/mol for 2) confirming the relevance of these interactions. The interactions have also been characterized by means of the non-covalent interaction (NCI) plot. (C) 2015 Elsevier Ltd. All rights reserved.