Synthesis, structure determination, and magnetic properties of pentakis[bis(hexafluoroacetylacetonato)1,2,4-triazinecopper(II)]

Abstract

Reaction of bis(hexafluoroacetylacetonato)copper(II) hydrate with 1,2,4-triazine (tz) in dichloromethane yields pentakis[bis(hexafluoroacetylacetonato)triazinecopper(II)] [Cu(hfac)₂(tz)]₅ (hfac = hexafluoroacetylacetonate) (1). The complex crystallizes in the triclinic space group P-1, with cell parameters a = 11.4124(5), b = 13.3405(5), c = 16.1794(7) Å, α = 93.360(2)°, β = 108.700(2)°, γ = 100.293(2)° at 120(1) K. In the complex, the copper(II) ions show three types of coordination polyhedra: square planar, square pyramidal, and octahedral (4 + 2). The tz ligand also shows different coordination modes (bridging and monodentate). In addition, disorder is observed in the triazine molecule, either through non-crystallographic two-fold rotation about the longitudinal N,N-axis, or with respect to a crystallographic center of symmetry. The crystal structure of 1 consists of alternating trimers and dimers. The weak coordination of the tz molecules results in negligible magnetic exchange through the ring.

Keywords:

• Disorder
• 1,2,4-Triazine
• Crystal structure
• Hexafluoroacetylacetone
• Cu(II)
• Magnetic exchange

Acknowledgements

The Quantum Design MPMS XL SQUID magnetometer was established at Clark University with the assistance of funds from the National Science Foundation (IMR-0314773). We are grateful to PCISynthesis Inc. for funds toward the purchase of the D8 Powder X-ray diffractometer, and the Kresge Foundation for funds toward the purchases of both. Research at Brandeis University was supported through National Science Foundation Grants DMR-0504000 and CHE-0521047.