A sterically hindered tetrakis(pyrazolyl)borate: Synthesis, characterization and coordinative behaviour

The sterically hindered tetrakis-(3-(p-tolylpyrazolyl)borate [pz0Tpp-Tol] has been prepared and its reaction with CuX2.nH2O (X = Cl or acetate (OAc), M(NO3)2.6H2O (M = Ni, or Co) and MCl2 (M = Zn or Cd) has been investigated. [M(pz0Tpp-Tol)X(Hpzp-Tol)] (M = Cu, X = Cl or OAc; M = Ni or Co, X = NO3) and [M(pz0Tpp-Tol)Cl(Hpzp-Tol)2-n(H2O)n] have been synthesised and their spectroscopic properties described, the five-coordinated Cu species being also structurally characterized. The methyl groups in the para-tolyl fragments of the ligand strongly influences the stoichiometry and structure of the metal complexes.