Structures of Fe(II) spin-crossover complexes from synchrotron powder-diffraction data.

Crystal structure determination and analysis have been carried out for the two spin-crossover compounds [Fe(teeX)(6)](BF(4))(2) (teeX is haloethyltetrazole; X = I: teei; X = Br: teeb), in both their high-spin (near 300 K) and their low-spin states (T = 90 K), using high-resolution powder-diffraction data collected at the ESRF (Grenoble, France) and SPring8 (Japan) synchrotron radiation facilities. The structures of teei have been solved using various direct-space structure determination techniques (grid search, genetic algorithm and parallel tempering) and refined with the Rietveld method using geometrical restraints. In the case of teeb, a structural model was found but a full refinement was not successful because of the presence of a significant amount of an amorphous component.

Strongly isolated ferromagnetic layers in poly-trans-mu-dichloro- and poly-trans-mu-dibromobis(1-(2-chloroethyl)-tetrazole-N4)copper(II) complexes.

Two new isostructural compounds, dichlorobis(1-(2-chloroethyl)tetrazole)copper(II) (1) and dibromobis(1-(2-chloroethyl)tetrazole)copper(II) (2), have been prepared. The synthesis, characterization, and spectral and magnetic properties as well as the crystal and molecular structures of 1 and 2 have been studied. Both complexes form two-dimensional, distorted square grid planes of copper and halides, distinctly separated by layers of tetrazole ligands.

Tetrakis[1-(3-chloropropyl)-1,2,4-triazole-kappaN4]bis(tetrafluoroborato-kappaF)copper(II).

In the title complex, [Cu(BF(4))(2)(1tpc)(4)] [1tpc is 1-(3-chloropropyl)-1,2,4-triazole, C(5)H(8)ClN(3)], the copper(II) centres reside in a tetragonally distorted octahedral coordination environment. Four 1tpc ligands are coordinated to the metal atom via the N4 atom of the triazole rings in a square-planar arrangement, with Cu-N bond lengths in the range 2.002 (2)-2.