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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 26, Number 9
BKCSDE 26(9)
September 20, 2005 

Cr(III)-Tetraaza Macrocyclic Complexes Containing Auxiliary Ligands (Part IV); Synthesis and Characterization of Cr(III)-Acetylacetonato, -Malonato and -Oxalato Macrocyclic Complexes
Jong Chul Byun*, Chung Hun Han
Macrocyclic Cr(III) complex, Acetylacetonato ligand, Crystal structure, Electronic absorption spectra
The reaction of cis-[Cr([14]-decane)(OH)2]+ ([14]-decane = rac-5,5,7,12,12,14-hexamethyl-1,4,8,11- teraazacyclotetradecane) with auxiliary ligands {La = acetylacetonate (acac), oxalate (ox) or malonate (mal)} leads to a new cis-[Cr([14]-decane)(acac)](ClO4)2·(1/2)H2O (1), cis-[Cr([14]-decane)(ox)]ClO4·(1/2)H2O (2) or cis-[Cr([14]-decane)(mal)]ClO4·(1/4)H2O (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)(acac)](ClO4)2·(1/2)H2O reveals that central chromium(III) has a distorted octahedral coordination environment and two acetylacetonate-oxygen atoms are bonded to the chromium(III) ion in the cis positions. The angle Naxial-Cr-Naxial deviates by 11o from the ideal value of 180o for a perfect octahedron. The bond angle O-Cr-O between the chromium(III) ion and the two acetylacetonate-oxygen atoms is close to 90o. The bond lengths of Cr-O between the chromium and the acetylacetonate-oxygen atoms are 1.950(3) and 1.954(2) 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 1560 {ν (C=O)}, 1710 {νas(OCO)} and 1660 cm-1 {νas(OCO)} attributed to the acac, ox and mal auxiliary ligands stretching vibrations, respectively.
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