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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 26, Number 7
BKCSDE 26(7)
July 20, 2005 

 
Title
Cr(III)-Tetraaza Macrocyclic Complexes Containing Auxiliary Ligands (Part III); Synthesis and Characterization of Cr(III)-Isothiocyanato, -Azido and -Chloroacetato Macrocyclic Complexes
Author
Jong Chul Byun*, Chung Hun Han, Yu Chul Park
Keywords
Cr(III) macrocyclic complex, Cr(III) isothiocyanato complex, Crystal structure, Absorption spectra
Abstract
The reaction of cis-[Cr([14]-decane)(OH2)2]+ ([14]-decane = rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-teraazacyclotetradecane) with auxiliary ligands {La = isothiocyanate (NCS-), azide (N3-) or chloroacetate(caa)} leads to a new cis-[Cr([14]-decane)(NCS)2]ClO4·H2O (1), cis-[Cr([14]-decane)(N3)2]ClO4 (2) or cis-[Cr([14]-decane)(caa)2]ClO4 (3). These complexes have been characterized by a combination of elemental analysis, conductivity, IR and Vis spectroscopy, mass spectrometry, and X-ray crystallography. Analysis of the crystal structure of cis-[Cr([14]-decane)(NCS)2]ClO4·H2O reveals that central chromium(III) has a distorted octahedral coordination environment and two NCS? anions are bonded to the chromium(III) ion via the Ndonor atom in the cis positions. The angle Naxial-Cr-Naxial deviates by 13o from the ideal value of 180o for a perfect octahedron. The bond angle N-Cr-N between the Cr(III) ion and the two nitrogen atoms of the isothiocyanate ligands is close to 90o. The bond lengths of Cr-N between the chromium and NCS- groups are 1.964(5) and 2.000(5) A. They are shorter than those between chromium and nitrogen atoms of the macrocycle. The IR spectra of 1, 2 and 3 display bands at 2073, 1344 and 1684 cm-1 attributed to the NCS-, N3- and caa groups stretching vibrations, respectively.
Page
1044 - 1050
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