Synthesis, Characterization and Single Crystal X-Ray Structures of Trifluroacetylacetonate Copper(II) Complexes

Three Cu(II) complexes of 1,1,1-trifluoroacetylacetonate, viz. [Cu(TFACAC)₂(MeOH)] (1), [Cu(TFACAC)₂(py)] (2) and [Cu(TFACAC)₂(DABCO)] (3) were synthesized and characterized by elemental analysis, IR, UV–Visible spectroscopy and cyclic voltammetry. Structures of complexes 1–3 were established by single crystal X-ray diffraction wherein 1 and 2 adapt square pyramidal geometry. Complex 1 crystallizes in triclinic space group P-₁, with a = 8.5059(6) Å, b = 9.3025(7) Å, c = 10.9906(8) Å, α = 75.684(2)°, β = 73.191(2)°, γ = 64.992(2)°, and Z = 2. X-ray crystallographic studies revealed that in complex 1, both, TFACC ligands and coordinated methanol are disordered over two conformations giving a combination of two isomers with cis to trans isomer ratio of 0.538:0.462. In complex 3 DABCO is acting as a bridging ligand connecting two Cu(II) centers thereby forming a 1-D polymer chain with each copper in octahedral coordination. The cyclic voltammograms of 1 and 3 give a quasi-reversible Cu(II)/Cu(I) peak with E_1/2 + 0.01 V and − 0.05 V respectively whereas complex 2 gives a one electron reversible Cu(II)/Cu(I) couple at E_1/2 = − 0.25 V.

Graphical Abstract

Three Cu(II) complexes of (1,1,1-trifluoroacetylacetonato) ligand with methanol, pyridine and DABCO occupying the axial positions are reported.