名称:
Racemic nickel(II) pyridine-2-aldoximate complexes capped by 2,2′-bipyridine and 1,10-phenanthroline: syntheses, structures and magnetic properties
摘要:
Two Ni(II) pyridine-2-aldoximate complexes, Ni(pao)(2)(bpy) (1) and Ni(pao)(2)(phen) (2) (pao(-)pyridine-2-aldoximate, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline), were synthesized via the deprotonation of NiCl2(Hpao)(2) in methanol followed by the addition of bidentate ligands of 2,2'-bipyridine and 1,10-phenanthroline. Crystallization in CHCl3 gave block-type crystals of 1 and 2 in high yields. The mononuclear structure surrounded by three bidentate ligands, i.e., two pao(-) and one bpy or phen, was revealed by X-ray crystallography: 1 crystallizes in monoclinic space group P2(1)/c with cell dimensions of a = 13.457(3) Angstrom, b = 14.493(3) Angstrom, c = 19.104(4) Angstrom, beta = 108.681(3)degrees, Z = 4, and 2 crystallizes in monoclinic space group P2(1)/n with cell dimensions of a = 14.235(5) Angstrom, b = 12.018(4) Angstrom, c = 20.696(7) Angstrom, beta = 110.304(4)degrees, Z = 4.1 and 2 each have two oximate groups (pao(-)), with an NO-trans arrangement around the Ni-II ion. Complexes 1 and 2 are racemic, namely, each molecule has a chiral center of Delta or Lambda, thereby forming NO-trans-Delta and -Lambda geometries in the solid state. Magnetic measurements revealed a paramagnetic S = 1 spin state with a positive zero-field splitting parameter. (C) 2003 Elsevier B.V. All rights reserved.