Syntheses, crystal structures, circular dichroism, and magnetic properties of chiral dinuclear and polymeric nickel(II) compounds

Title
Syntheses, crystal structures, circular dichroism, and magnetic properties of chiral dinuclear and polymeric nickel(II) compounds
Author(s)
신종원[신종원]손효진[손효진]김석규민길식[민길식]
Keywords
MACROCYCLIC NICKEL(II); COMPLEXES; OXALATO; SPECTRA; LIGAND; CHAIN; IONS; ACID
Issue Date
201303
Publisher
PERGAMON-ELSEVIER SCIENCE LTD
Citation
POLYHEDRON, v.52, pp.1206 - 1212
Abstract
Chiral dinuclear nickel(II) complexes, [Ni(L-R,L-R)(C2O4)Ni(L-R,L-R)](ClO4)(2)center dot 4CH(3)CN (3) and [Ni(L-S,L-S)(C2O4) Ni(L-S,L-S)](ClO4)(2)center dot 4CH(3)CN (4) and chiral polymeric compounds, [Ni(L-R,L-R)(CrO4)]n center dot 2H(2)O center dot CH3CN (5) and [Ni(L-S,L-S)(CrO4)]n center dot 2H(2)O center dot CH3CN (6) have been synthesized and characterized (L-R,L-R/S,L-S = 1,8-di((R/S)-alpha-methylbenzyl)-1,3,6,8,10,13-hexaazacyclotetradecane). These chiral compounds were characterized by X-ray crystallography, circular dichroism, and molecular magnetism. The nickel(II) ions in 3 and 4 have a distorted octahedral geometry by coordination with four nitrogens of a macrocyclic ligand with chiral pendents in a folded conformation and two oxygens of an oxalate ion in the cis positions. The nickel(II) ions in 5 and 6 have a distorted octahedral geometry by coordination with four nitrogens of a macrocyclic ligand in a planar conformation and two oxygens of two chromate ions in the axial positions. Complexes 3 and 4 show strong antiferromagnetic interactions [3: g = 2.36, J/k(B) = -29.9 K (-20.8 cm(-1)); 4: g= 2.18, J/k(B) = -25.5 K (-17.7 cm(-1))], while 5 and 6 exhibit weak antiferromagnetic couplings [5: g= 2.25, J/k(B) = -1.20 K (-0.83 cm(-1)); 6: g = 2.25, J/k(B) = -0.68 K (-0.47 cm(-1))]. The former complexes occur strong antiferromagnetic interactions via the oxalato bridges within the nickel(II) dimers, the latter compounds are weak antiferromagnetic interactions through the chromate ions within the 1D polymers. The circular dichroism (CD) spectrum of 3 has exhibited two negative peaks at 336 and 533 nm, and that of 4 has displayed an enantiomeric pattern. The CD spectrum of 5 has appeared a negative absorption above ca. 550 nm, while that of 6 has shown an enantiomeric pattern in the same wavelength region. (C) 2012 Elsevier Ltd. All rights reserved.
URI
http://hdl.handle.net/YU.REPOSITORY/26223http://dx.doi.org/10.1016/j.poly.2012.06.041
ISSN
0277-5387
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이과대학 > 화학생화학부 > Articles
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