Pentacoordinated bis-o-benzosemiquinonato zinc complexes with different N-ligands: Structure and magnetic properties

New pentacoordinated paramagnetic bis-o-semiquinonato zinc complexes with different neutral ligands (3,6-SQ)(2)Zn center dot L 1-5 (where 3,6-SQ - 3,6-di-tert-butyl-o-semiquinonate anion, L = 2,6-dimethyl-N-(thiophen-2-ylmethylene)aniline (L-1) (1), 2,6-diisopropyl-N-(pyridin-4-ylmethylene)aniline (L-2) (2), N-(pyridin-4-ylmethylene)aniline (L-3) (3), 2-(4-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (L-4) (4) and 4,4'-dipyridyl (L-5) (5)) were synthesized. The crystal structures of compounds 1-3, 5 were investigated using X-ray diffraction. The coordination polyhedron of all complexes was found to be a distorted tau = 0-0.3) square pyramid. The measurements of magnetic susceptibilities show that all complexes are characterized by the intramolecular antiferromagnetic exchange between o-semiquinonate radical centers J = -155.76(28), -53.56(18), -52.57(25), -80.67(27) and -85.77(91)K for 1-5 respectively). The magnitude of the magnetic exchange interactions between spins of semiquinonate ligands was found to be influenced by the radical separation distance. A smaller distance between radical centers leads to the increasing magnetic exchange interaction magnitude. (C) 2016 Elsevier B.V. All rights reserved.