Unusual coordination behavior by a hydroxypyridine/pyridone ligand: Synthesis and structure of [(2-bromo-4-hydroxypyridine)₂(2-bromo-1(H)-4-pyridone)₂copper(II)] perchlorate • 2(2-bromo-4-hydroxypyridine) • 2(2-bromo-1(H)-4-pyridone)

Abstract

The synthesis and structure of [Cu(2-Br-4-HOpy)₂(2-Br-4-pyone)₂](ClO₄)₂ • 2(2-Br-4-HOpy) • 2(2-Br-4-pyone) is reported [2-Br-4-HOpy = 2-bromo-4-hydroxypyridine; 2-Br-4-pyone = 2-bromo-(1H)4-pyridone]. The compound forms as a co-crystal in the triclinic P-1 space group with four-coordinate Cu(II) ions and perchlorate geganions interacting with both the hydroxypyridine and pyridone forms of the organic molecule through hydrogen and halogen bonding. The coordination complex exhibits the unusual coordination motif of having both the hydroxypyridine and pyridone tautomers of the ligand coordinated to the same metal ion. The isolation of the Cu complex by the organic groups suggests an absence of magnetic exchange within the sample which is confirmed by variable temperature magnetization measurements and EPR data.

Keywords:

• Tautomers
• Cu(II)
• Coordination mode
• Hydroxypyridine/pyridone

Acknowledgements

The authors are grateful for funds from PCISynthesis, Inc. (now SEQENS) toward the purchase of the X-ray powder diffractometer, the National Science Foundation (IMR-0314773) toward the purchase of the MPMS SQUID magnetometer and the Kresge Foundation toward the purchase of both.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

PCI Synthesis; US National Science Foundation.