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

Abstract

Two new fluoride-containing co-ordination compounds [C~(Him), (H,0)~1 F2 and [Cu(Him),] [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),( H20)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 = 13.91 5(3) A, p = 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 Fions 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.

Structure of tetrakis(imidazole)copper(II) diiodide

“…The non-coordinated N atoms on opposite rings are in an inverted position with respect to each other as has been found in similar structures (Vreugdenhil, Birker, ten Hoedt, Verschoor & Reedijk, 1984;Gtowiak & Wn~k, 1985). Three of the rings are close to being parallel with the linear I 1--Cu--I2 direction [average torsion angle I2--Cu--N(coord.)--N(uncoord.)…”

“…and [Cu(imH)4(NO3)2], with values of 2.000-2.021, 1.998-2.010, 1.984-2.033, 2.018-2.020 and 2.008-2.018/k, respectively (Fransson & Lundberg, 1972;Ivarsson, 1973;Vreugdenhil, Birker, ten Hoedt, Verschoor & Reedijk, 1984;Gtowiak & Wn~k, 1985;McFadden, McPhail, Garner & Mabbs, 1976 The copper-iodide interactions are weak (3.406 for I1 and 3.865 A for I2) but are definitely in the fifth and sixth coordination sites as indicated by the angles around copper (I1--Cu--I2 179.3; I1--Cu--N1,N2,N3,N4 from 90.7 to 93.4; I2--Cu--N1,N2,N3,N4 from 86.2 to 89.8°). The only known copper(II)-iodide distances are for five-coordinate complexes and these range from 2.672 to 2.718 A for compounds such as [Cu(phen)2I]I.H20 (Nagle & Hathaway, 1991;Hambley, Raston & White, 1977;Hathaway & Murphy, 1980;Barclay, Hoskins & Kennard, 1963).…”

Structures of four complexes of copper with N-methylimidazole and chloro ligands

“…4), [Cu(Meim)4(H20)2]C12.H20, with the presence of two water molecules as axial ligands. The Cu-O bond lengths of 2.511 (3) and 2.518 (3),/k indicate a rather weak attachment and these Cu-O distances are in the range observed for semi-coordination (Hathaway & Tomlinson, 1970;Hathaway & Billing, 1970), but are shorter than the values of 2.638,~ observed by Vreugdenhil et al (1984) for the compound [Cu(Him)4(H20)2]F 2, in which the strong hydrogen-bonding interaction weakens the axial interaction of the water molecules with the Cu ion. (4) contains two crystallographically independent cations, each located on a centre of symmetry.…”

Coordination chemistry beyond Werner: interplay between hydrogen bonding and coordination

“…7. 25 Here each fluoride is pseudo-tetrahedrally ''coordinated'' by 4 H atoms: 2 from water and 2 from imidazoles. So to summarize the pyrazoles and imidazoles: in pyrazoles the H bond donor function of NH is used intramolecularly, whereas in imidazoles the NH is stabilizing (in this case) anions NOT in the coordination sphere.…”