Issue 12, 2016

Crystal structure and physical properties of 1-methyl-3-(carboxymethyl)benzimidazolium betaine·CuBr2 in crystal and water solution

Abstract

A new Cu(II) carboxylate coordinating compound [1-methyl-3-carboxymethyl benzimidazolium betaine]2CuBr2 was synthesized and crystallized. The crystal has the triclinic symmetry P[1 with combining macron], with unit cell dimensions a = 7.9693, b = 8.4129, c = 9.1302 Å, α = 68.058, β = 85.402 and γ = 71.258 deg. (Z = 1), and molecules stacked along the a-axis. Cu(II)-complexes are planar and four-coordinated with chromophore CuO2Br2, where two oxygen atoms belong to the carboxylate groups of two betaines acting as unidentate ligands. The compound was characterized by two-dimensional 1H and 13C NMR spectroscopy for the determination of the correlation between protons of a ligand molecule. NMR spectra confirm the coordination of Cu(II) ions and allow identification of H(2) proton as easily detached in basic conditions. FT-IR spectra confirm the unidentate coordination of the betaine carboxylate group. UV-Vis spectra show three bands in d–d-transition region. Energies of these transitions were used in the interpretation of the EPR results. From powder and single crystal EPR measurements the g-factors were determined as gx = 2.072, gy = 2.030, gz = 2.241. A non-typical g-factor sequence is a consequence of the orbital mixing in the ground state of Cu(II) complex of D2h symmetry. The g-factors were interpreted in terms of the Molecular Orbital (MO) theory which delivered the Cu(II) unpaired electron density delocalization onto the ligand molecules. A strong delocalization on betaine molecules via in-plane ground-state orbital was found and unexpectedly also via out-of plane orbital directed towards the non-coordinating oxygen of the betaine carboxylate group.

Graphical abstract: Crystal structure and physical properties of 1-methyl-3-(carboxymethyl)benzimidazolium betaine·CuBr2 in crystal and water solution

Supplementary files

Article information

Article type
Paper
Submitted
11 Oct 2016
Accepted
09 Nov 2016
First published
10 Nov 2016
This article is Open Access
Creative Commons BY license

New J. Chem., 2016,40, 10526-10535

Crystal structure and physical properties of 1-methyl-3-(carboxymethyl)benzimidazolium betaine·CuBr2 in crystal and water solution

Ł. Czekański, S. K. Hoffmann, P. Barczyński, A. Gąsowska, R. Bregier-Jarzębowska, A. Zalewska, J. Goslar, M. Ratajczak-Sitarz and A. Katrusiak, New J. Chem., 2016, 40, 10526 DOI: 10.1039/C6NJ03192G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements