Synthesis, crystal structure, and EPR studies of the five-coordinate [CUCl3(H2O)(2)](-)complex in (dabcoH(2))(2)Cl-3[CuCl3(H2O)(2)]center dot H2O

The compound (dabcoH(2))(2)Cl-3[CuCl3(H2O)(2)]. H2O, where dabco = 1,4-diazabicyclo[2.2.2]octane, has been synthesized, its structure has been determined by single-crystal structural analysis, and its properties have been investigated by powder and single-crystal EPR spectroscopy. The compound crystallizes in space group Pnma at room temperature with unit cell dimensions of a = 15.227(1) Angstrom, b = 7.467(1) Angstrom, and c = 20.166(2) Angstrom with Z = 4. The structure was solved by the Patterson method and refined by full-matrix least-squares to R = 4.3% for 1681 observed reflections (I > 2 sigma(I)). The [CuCl3(H2O)(2)](-) anion exists with a slightly distorted trigonal bipyramidal geometry in which the three Cl atoms lie in equatorial positions and the two water molecules are in axial positions. The distortion appears to be driven by the presence of N-H ... Cl hydrogen bonds. The EPR spectra are also consistent with the presence of only a small distortion from trigonal bipyramidal geometry since g(1) similar to g(2) > g(3) approximate to 2.0. Analysis of the geometry indicates the distortion consists primarily of a ''negative'' C-2 upsilon type. Analysis of the thermal parameters supports the supposition that the observed geometry corresponds to disorder over two ''positive'' C-2 upsilon distortions.