A Novel μ1,1-Azido-, μ2-Alkoxo-, and μ2-Phenoxo-Bridged Tetranuclear Copper(ii) Complex with a Quinquedentate Schiff-Base Ligand: Magneto-Structural and DFT Studies

Subhra Basak; Soma Sen; Georgina Rosair; Cédric Desplanches; Eugenio Garribba; Samiran Mitra

doi:10.1071/CH08511

RESEARCH ARTICLE

A Novel μ_1,1-Azido-, μ₂-Alkoxo-, and μ₂-Phenoxo-Bridged Tetranuclear Copper(ii) Complex with a Quinquedentate Schiff-Base Ligand: Magneto-Structural and DFT Studies

Subhra Basak ^A , Soma Sen ^A ^B , Georgina Rosair ^C , Cédric Desplanches ^D , Eugenio Garribba ^E and Samiran Mitra ^A ^F

+ Author Affiliations

- Author Affiliations

^A Department of Chemistry, Jadavpur University, Kolkata – 700 032, West Bengal, India.

^B Current address: Rishi Bankim Chandra College, Kantalpara, Naihati, 24 Parganas (N), West Bengal, India.

^C Department of Chemistry, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.

^D Institut de Chimie de la Matière Condensée de Bordeaux UPR 9048 CNRS, Université Bordeaux 1, 87 Avenue Dr Schweitzer, 33608 Pessac, Cedex, France.

^E Dipartimento di Chimica, Università degli Studi di Sassari, Via Vienna 2, I-07100 Sassari, Italy.

^F Corresponding author. Email: smitra_2002@yahoo.com

Australian Journal of Chemistry 62(4) 366-375 https://doi.org/10.1071/CH08511
Submitted: 20 November 2008 Accepted: 24 February 2009 Published: 24 April 2009

Abstract

A novel tetranuclear copper(ii) complex [Cu₄L₂(μ_1,1- N₃)₂]·CH₃CN (1) has been synthesized using a symmetrical quinquedentate N₂O₃-donor Schiff-base ligand H₃L (N,N′-(2-hydroxypropane-1,3-diyl)bis(2- hydroxyacetophenimine)) and characterized by elemental analysis, Fourier-transform (FT)-IR, UV-visible, electron paramagnetic resonance spectroscopy, and cyclic voltammetry. The X-ray single-crystal structure of 1 reveals three kinds of bridges among the four metal centres: one from the exogenous azido ligand and two from the phenoxo and alkoxo moieties of the Schiff base. The same structure highlights the remarkable versatility of copper(ii) to adopt an array of stereochemistries. Four unusual eight-membered metallacycles exist in 1. The μ_1,1-azido, μ₂-alkoxo, and μ₂-phenoxo bridges among the four copper centres have facilitated interesting magnetic interactions that have been elucidated by variable-temperature magnetic susceptibility measurements and backed up by density functional theory calculations. Detailed analyses have shown that the antiferromagnetic effect through the alkoxo-bridged Cu^II centres combined with the ferromagnetic interaction through the azido-bridged metal centres results in an S = 0 ground state.

Acknowledgements

Subhra Basak gratefully acknowledges the DRDO, New Delhi, India, for financial assistance. Our thanks are also extended to the All India Council for Technical Education (AICTE), New Delhi, India. We are thankful to Professor S. Bhattacharya and Dr S. Halder, Department of Chemistry, Jadavpur University, Kolkata, India, for the electrochemical study.

References

A Novel μ1,1-Azido-, μ2-Alkoxo-, and μ2-Phenoxo-Bridged Tetranuclear Copper(ii) Complex with a Quinquedentate Schiff-Base Ligand: Magneto-Structural and DFT Studies

Abstract

Acknowledgements

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A Novel μ_1,1-Azido-, μ₂-Alkoxo-, and μ₂-Phenoxo-Bridged Tetranuclear Copper(ii) Complex with a Quinquedentate Schiff-Base Ligand: Magneto-Structural and DFT Studies