NICKEL COMPLEXES OF PYRAZOLYL BORATE AND THEIR CATALYTIC ACTIVITIES

Abstract

Addition of potassium hydrotris(3-phenyl-5-methyl-pyrazolyl)borate ligand [KTpPh, Me] to a solution of NiC12 and 3-phenyl-5-methyl-pyrazole [pzPh, MeH] in dichloro methane and methanol yields the structurally characterized complex 2 [Ni(TpPh,Me)(pzPI,Me)Cl] which is further reacted with different substituted benzoates to form complexes type [Ni(TpPh,Me)(pZPh,Me)(X-OBz)] (X = H, Me, OMe, NO2, Cl, F, CHO, CN, NH2, OH). IR spectroscopy confirms that TpPh, Me ligand is a3 coordinated in all the complexes and the benzoates are coordinated as monodentate terminally. Also the reaction of complex 2 with NaN3, KCN, KSCN in methanol and toluene yields [Ni(TpPh,Me)(pzPh'Me)(Y)] (Y = N3, NCS, CN) the IR spectra shows the monodentate terminal binding of these ligands. The magnetic susceptibility studies suggest that complexes 2-16 are paramagnetic with two unpaired electrons. The X-ray crystallographic studies of 2-5, 7 and 13-15 reveals the distorted square pyramidal nickel centre. Thermogravimetric measurements were also carried out to all the complexes to check their thermal stabilities.inally the SOD activity of complexes 2-16 for 50% inhibition of superoxide ions in biological system shows the activity of complexes at different