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Structural and spectroscopic properties of trans-dichlorobis(2,2-dimethyl-1,3-diaminopropane)chromium(III) chloride

Lookup NU author(s): Professor William Clegg, Gary Nichol, Professor Mohammad Habibi

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Abstract

The structure of trans-[CrCl2(Me2tn)2]Cl (Me2tn = 2,2-dimethylpropane-1,3-diamine) has been determined by a single-crystal X-ray diffraction study at 150 K. The analysis reveals that there are two independent Cr(III) complex cations in the structure, one with crystallographic inversion symmetry and the other with two-fold rotation symmetry, which are conformational isomers of each other. In both conformations, the chromium atom adopts a distorted octahedral structure with the four nitrogen atoms of two Me2tn ligands occuping the equatorial plane and two chlorine atoms occuping trans-axial positions. The six-membered chelate rings are in stable chair conformations with N-Cr-N angles of 87.03(8)° and 88.99(8)°. The two chelate rings in the centrosymmetric complex cation 1 are anti, while those in the rotation-symmetric complex cation 2 are in syn conformations. The mean Cr-N and Cr-Cl bond lengths are 2.0922 and 2.3253 Å, respectively. The infrared and UV-visible absorption spectra of trans-[CrCl2(Me2tn)2]Cl have also been measured. The resolved band maxima of the electronic d-d spectrum are fitted with a secular determinant for a quartet energy state of the d3 configuration in a tetragonal field including configurational but neglecting spin-orbit coupling. It is confirmed that the nitrogen atoms of the Me2tn ligand have a strong σ-donor character, but the chloro ligand has weak σ- and π-donor properties toward the chromium(III) ion. © 2007 Elsevier B.V. All rights reserved.

Publication metadata

Author(s): Choi J-H, Clegg W, Nichol GS, Lee SH, Park YC, Habibi MH

Publication type: Article

Publication status: Published

Journal: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

Year: 2007

Volume: 68

Issue: 3

Pages: 796-801

ISSN (print): 1386-1425

ISSN (electronic): 1873-3557

Publisher: Elsevier BV

URL: http://dx.doi.org/10.1016/j.saa.2007.01.002

DOI: 10.1016/j.saa.2007.01.002

PubMed id: 17307384

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