Doubly Pyridazine-bridged Dicobalt(ii) and Dinickel(ii) Side-by-side Complexes of Variously Substituted Conjugated Bis-bidentate Ligands

Jason R. Price; Yanhua Lan; Boujemaa Moubaraki; Keith S. Murray; Sally Brooker

doi:10.1071/CH09614

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Doubly Pyridazine-bridged Dicobalt(ii) and Dinickel(ii) Side-by-side Complexes of Variously Substituted Conjugated Bis-bidentate Ligands

Jason R. Price ^A , Yanhua Lan ^A , Boujemaa Moubaraki ^B , Keith S. Murray ^B and Sally Brooker ^A ^C

+ Author Affiliations

- Author Affiliations

^A Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin, New Zealand.

^B School of Chemistry, Monash University, PO Box 23, Clayton, Vic. 3800, Australia.

^C Corresponding author. Email: sbrooker@chemistry.otago.ac.nz

Australian Journal of Chemistry 63(5) 779-784 https://doi.org/10.1071/CH09614
Submitted: 27 November 2009 Accepted: 6 January 2010 Published: 21 May 2010

Abstract

A family of six acyclic bis-bidentate Schiff base ligands, L^x (prepared by condensation of 3,6-diformylpyridazine with a range of anilines: 2,4-dimethylaniline L^o,p-Me; 3,5-dichloroaniline L^m,m-Cl; 3,5-difluoroaniline L^m,m-F; p-toluidine L^p-Me; 4-aminophenol L^p-OH; 2,4,6-trimethylaniline L^o,o,p-Me), was complexed, 1:1, with cobalt(ii) or nickel(ii) perchlorate or tetrafluoroborate in refluxing dry acetonitrile. A family of dinuclear, doubly pyridazine-bridged complexes, M₂^II(L^x)₂(solvent)_n(ClO₄)₄ and [Ni₂(L^o,o,p-Me)₂(2H₂O)₄](BF₄)₄, resulted. An X-ray crystal structure determination on [Co₂^II(L^o,o,p)₂(H₂O)₂(MeCN)₂](ClO₄)₄·MeCN confirmed that it has the expected side-by-side architecture with axial solvent molecules completing the octahedral coordination sphere of the two cobalt(ii) ions. Magnetic analysis showed that the pyridazine bridges mediate weak-to-medium antiferromagnetic interactions between the metal ions. Specifically, for the cobalt(ii) complexes J was in the range –12 to –6 cm^–1, while for the nickel(ii) complexes J was in the range –22 to –17 cm^–1. There is no clear cut correlation of J values with electron-donating or -attracting properties of ligand substituent peripheral groups, although it is noted that the smallest J occurs in both the NiNi and CoCo families for the ligand L^o,o,p-Me.

Acknowledgements

This work was supported by grants from the University of Otago (including a Postgraduate Scholarship to Y.L.), the Marsden Fund (Royal Society of New Zealand; including a Postdoctoral Research Fellowship to J.R.P.) and the MacDiarmid Institute. We also thank the Australian Research Council for a Discovery grant to K.S.M., and I. Stewart, M. G. Cowan and J. E. M. Lewis (Otago) for their help with ESI MS.

References

Doubly Pyridazine-bridged Dicobalt(ii) and Dinickel(ii) Side-by-side Complexes of Variously Substituted Conjugated Bis-bidentate Ligands

Abstract

Acknowledgements

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