Tetrakis(imidazole)copper(II) fluorides. The crystal and molecular structure of diaquatetrakis(imidazole)copper(II) difluoride

Abstract

Two new fluoride-containing co-ordination compounds [Cu(Him)₄(H₂O)₂]F₂ and [Cu(Him)₄][BF₄]F (Him = imidazole) are described. From i.r. spectra, ligand-field spectra, and e.s.r. spectra it is concluded that the fluoride ions in both compounds are not co-ordinated to the metal ion. The crystal structure determination of [Cu(Him)₄(H₂O)₂]F₂ confirmed these conclusions. The compound crystallizes in space group C2/c, with cell dimensions a= 12.708(3), b= 10.299(2), c= 13.915(3)Å; β= 106.63(2)°, and Z= 4. The structure was solved using direct phasing and difference-Fourier techniques and refined by full-matrix least-squares methods. The final discrepancy factor, R= 0.027, was based on 1 468 reflections. The copper ions are co-ordinated by four imidazoles and two water molecules. The F^– ions are not co-ordinated to copper. They are strongly hydrogen bonded in a distorted tetrahedron of two imidazole H atoms and two H atoms of water molecules.