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, [Ni2(dmpn)2(hap)2(μ1,1-N3)2] and [Ni2(dmpn)2(han)2(μ1,1-N3)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/π interactions form supramolecular chains both in 1 and 2. DFT calculations reveal that C–H/π interaction energies are large negative (ΔE1 = –12.9 kcal/mol for 1 and ΔE2 = –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.

Graphical abstractSingle crystal X-ray diffraction analyses confirm the structures of two centrosymmetric dinuclear nickel(II) complexes and variable temperature magnetic susceptibility measurements indicate the presence of ferromagnetic coupling interactions, which were also corroborated by DFT analysis. C–H/π interaction energies are found to be large negative. The interactions have also been characterized by means of NCI plot.Figure optionsDownload full-size imageDownload as PowerPoint slide