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{pz^An}₃] (pz^An = 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{pz^An}₃)]( I ). But the reaction of K[HB{Pz^An}₃] with anhydrous CuCl₂ afforded CuCl(pz^AnH)(HB{pz^An}₃)( II ). The EPR spectra of I and II in benzene solution exhibit a pseudoaxial symmetrical {d_x2-y2}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 R_w = 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°.