SYNTHESIS, X-RAY STRUCTURE, SPECTROSCOPIC AND MAGNETIC-PROPERTIES OF IAZOLE-N',N1)(AQUA)COPPER(II)]BIS(HYDROGENSULFATE)

The synthesis, crystal structure, spectroscopic and magnetic propertie s of a five-coordinated mononuclear copper(II) compound with the ligan d 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (abbreviated as abpt) i s reported. The compound 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole- N',Nl )(aqua)copper(II)], [Cu(abpt)(2)(H2O)](HSO4)(2), crystallizes in the triclinic space group C2/c, with a=15.0685(9), b=9.6108(5), c=19. 691(1) Angstrom, beta=93.611(5)degrees, V=2846.0(3) Angstrom(3) and Z= 4. The least-squares refinement based on 2028 significant reflections, with I>2.5 sigma(1), converged to R=0.037 and R-w=0.043. The molecula r structure consists of a mononuclear five-coordinated copper(LI) cati on. Two abpt ligands act as didentate chelating ligands with Cu-N(I)=1 .958(3), Cu-N(SI)=2.066(3) Angstrom and an N(1)-Cu-N(51) angle of 80.1 (1)degrees. A water molecule is coordinated (Cu-O(1)=2.124(4) Angstrom ). The Cu and O(1) are in special positions. The anions are the unusua l hydrogensulfate (HSO;) which have remarkably short acceptor hydrogen bonds to the same coordinating water molecule (O(1)-O(13) (1-x, y, 0. 50-z)=2.701(4), H(1)-O(13) (1-x, y, 0.50-z)=1.74(4) Angstrom, O(1)-H(1 )... O(13) (1-x, y, 0.50-z)=167(4)degrees). Absorptions of the (low sy mmetry) hydrogen bonded hydrogensulfate anion can easily be found in t he LR spectrum. The X-band powder electron paramagnetic resonance spec tra show the usual rhombic spectrum for a copper(II) ion in a five-coo rdination. Despite the strong hydrogen-bonding network no evidence for Cu Cu exchange splittings are observed, in agreement with the magneti c susceptibility measurements over the temperature range 4.2-290 K, wh ere the product of the magnetic susceptibility and the temperature rem ains constant at 0.325 cm(3) mol(-1) K. (C) 1998 Elsevier Science S.A.