Issue 108, 2014

Structural, spectroscopic and magnetic properties of a novel copper(ii) l-tyrosinato complex

Abstract

The complex [Cu(L-Tyr)2(H2O)]·H2O (1) (L-Tyr = L-tyrosine) was obtained as crystals and characterized by X-ray, spectroscopic (FT-IR, FT-Raman, NIR-vis-UV, and EPR) and magnetic methods. The monomeric complex crystallized in the monoclinic P21 symmetry with a = 11.967 (1) Å, b = 5.9986 (4) Å, c = 14.936 (1) Å. The amino N and carboxylate O atoms of chelating L-tyrosinate anions together with the O atom of water molecules create a slightly distorted square pyramidal environment around the Cu(II) ions (τ = 0.11). The distance of about 5.998(1) Å [Cu(L-Tyr)2(H2O)] units is involved in a polymeric chain based on N(1)–H⋯O(4)vi and N(2)–H⋯O(5)vi hydrogen bonds. The d–d band found in the polycrystalline-reflectance spectrum at 15 700 cm−1 is composed of three 2B1(dx2–y2) → 2A1 (dz2), 2B12B2(dxy) and 2B12E (dxz ≈ dyz) transitions with energies 14 880, 15 800 and 19 950 cm−1, respectively. In DMSO solution the complex preserves its square pyramidal geometry as evidenced by an intensive band at ca. 16 400 cm−1. The EPR spectral parameters for powder (g = 2.236 and g = 2.063) and DMSO frozen solution (g = 2.250, g = 2.055, and A = 180 G) correspond to an axial symmetry of the Cu(II) coordination geometry with the dx2–y2 orbital as a ground state of the unpaired electron. Furthermore, the frozen solution spectrum revealed signals corresponding to S = 1 spin states of Cu(II) ions coupled by dipole–dipole interactions with distinctly resolved hyperfine splitting due to two copper nuclei (|D| = 0.0468 cm−1, g = 2.238, g = 2.06 and A = 85 G). The variable-temperature magnetic susceptibility measurements revealed the existence of a weak ferromagnetic interaction between neighboring copper(II) ions through the N–H⋯O hydrogen bonds.

Graphical abstract: Structural, spectroscopic and magnetic properties of a novel copper(ii) l-tyrosinato complex

Supplementary files

Article information

Article type
Paper
Submitted
19 Sep 2014
Accepted
07 Nov 2014
First published
07 Nov 2014

RSC Adv., 2014,4, 63150-63161

Author version available

Structural, spectroscopic and magnetic properties of a novel copper(II) L-tyrosinato complex

A. Wojciechowska, A. Gągor, J. Jezierska and M. Duczmal, RSC Adv., 2014, 4, 63150 DOI: 10.1039/C4RA10717A

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