New binuclear copper(II) complex with 2-thiopheneacetic acid. Synthesis, X-ray diffraction and vibrational studies of bis(N,N-dimethylformamide)tetra(2-thiopheneacetato)dicopper(II)

Green crystals of the [Cu(taa)2(dmf)]2 (where taa denotes 2-thiopheneacetate anion) complex crystallize from the dmf solution of another polymeric [Cu2(taa)4]n complex. Obtained compound was investigated by X-ray diffraction methods, which revealed that the complex consists of centrosymmetric dimers where the bidentate 2-thiopheneacetate anions form syn, syn bridges between copper(II) ions. The coordination polyhedron of each metal ion is completed by the dmf molecule. The complex structure is well reflected in the infrared spectrum, where the assignment of the bands originating from the Cu–COO and Cu–dmf vibrations was confirmed with the aid of metal isotope substitution. q 2004 Elsevier B.V. All rights reserved.