Studies on transition-metal complexes containing the scorpionate ligand(I) - synthesis, characterization and crystal structure of copper(II) complexes with hydrotris[3-{p-methoxyphenyl (pyrazol-1-yl)}]borate

A scorpionate ligand K[HB{pzAn}3] (pzAn = 3-{p-methoxyphenyl} pyrazole) was prepared, which was reacted with one molar equivalent of Cu(O2CMe)2 · H2O in THF at room temperature, yielding [Cu(O2CMe)(HB{pzAn}3)](I). But the reaction of K[HB{pzAn}3] with anhydrous CuCl2 afforded CuCl(pzAnH)(HB{pzAn}3)(II). The EPR spectra of I and II in benzene solution exhibit a pseudoaxial symmetrical {dx(2)-y(2)}1 configuration at copper. Both I and II are characterized by IR, elementary analysis and CV. The crystal structure of compound II has been determined. Crystals are monoclinic, space group P21/c with a = 1.164 3(2) nm, b = 2.708 1(5) nm, c = 1.449 4(3) nm, β = 105.37 (3)°, V = 4.406 6(14) nm3 and Z = 4, with final residuals R = 0.060 4 and Rw = 0.141 6. The complex shows a distorted square pyramidal copper center, and exhibits a weak intramolecular hydrogen bond, N-H...Cl, with bond length of Cl...N 0.300 9 nm and bond angle of Cl...H-N 120.3°.