Syntheses And Characterization Of The Novel Pyrazolyl/triazolyl Tridentate N₂O Ligands And Their Ni(Ⅱ), Pd(Ⅱ) And Cu(Ⅱ) Complexes

Since the initial development of two new tris(pyrazol-l-yl)borate and poly(pyrazol-l-yl)methane ligands by Trofimenko in the 1960s, this type of ligands have developed greatly in transition metal chemistry, bioinorganic chemistry and organometallic chemistry. A significant number of complexes using most metals of the periodic table have been prepared with these ligands and studied their catalysis on olefin polymerization. In recent years, people began to design and synthesize N, N, O ligands derived from bis(pyrazol-l-yl)methane similar to these two types of ligands. Because of the character of "scorpionate" ligands and their preference to forming polydentate structure with most metals, more attentions have also been paid for the synthesis of small metal complexes to mimicing active centers of metalloenzymes and for the catalytic oxo-polymerization of phenols mimicing the property of peroxidase. It is therefore of importance to study this type of ligands and their complexes. In the first part of this dissertation, tris(pyrazol-l-yl)methane, bis(pyrazol-l-yl)methane, pyrazole-based N,N,O(S) ligands and their complexes are reviewed briefly.In the second part of this dissertation, four N, N, O ligands with pyrazole-l-yl or trizol-1-yl groups and their ten Ni(II) and Pd(II) complexes were synthesized. Their physicochemical properties were characterized by the Elemental Analysis, ¹H NMR spectra, Infrared spectra and TG-DSC analyses. Single crystals of three complexes of them, suitable for X-ray diffraction analysis, were grown and their structures were determined. The unit-cell parameters were listed below: compound 5 Ni₂(dpzhp)₂ (ClO₄)₂·2(CH₃CN) was monoclinic with space group P2(1)/c and unit-cell parameters of a=l. 1709(2) nm, b=l.2527(3) nm, c=l.4259(3) nm;compound 7 Pd( Hdpzhp)Cl₂ was monoclinic with space group C2/c and unit-cell parameters of a=2.3861(3) nm, b= 0.89216(10) nm, c=1.64322(18) nm;compound 10 Pd(Hmppzhp)Cl₂ was monoclinic with space group P2(l)/c and unit-cell parameters of a=0.88868(18) nm, b=l.6192(3) nm, c=l.6228(3) nm. All nickel complexes are dinuclear commonly, in which two nickel atoms were bridged by two oxygen atoms of hydroxyl anions and forming a square-planar enviro nment. The corresponding palladium(II) complexes containmononuclear and binuclear compounds, however, of which the complexes derived from the ligands and PdC^ are mononuclear with no ligation of the oxygen atom of the hydroxyl group of the ligands, while the products synthesized from Pd(NO3)2 and the identical ligands are possibly binuclear, similar in structure to the corresponding nickel compounds.In the third part, eleven new copper(II) complexes were synthesized by reaction between copper salts and our synthesized N, N, O ligands. These compounds were also undergone the Elemental analysis, Infrared spectra and TG-DSC analysis. The crystal structures of five complexes were determined by X-ray diffraction analysis. The unit-cell parameters were listed below: compound 17Cu2(dpzhp)2Br2-2(CH3OH) was orthorhombic with space group Pbca and unit-cell parameters of a=1.1914(4) nm, b=l.6368(5) nm, c=l.8237(6) nm;compound 18 Cu2(mppzhp)2(NO3)2-2(CH3OH) was monoclinic with space group P2(l)/n and unit-cell parameters of a= 1.1017(6) nm, b=l .5143(9) nm, c=l .4906(8) nm;compound 19 Cu2(mppzhp)2(ClO4)2 was monoclinic with space group P2(l)/c and unit-cell parameters of a=1.01581(16) nm, b=l .43991(17) nm, c=l.57485(16) nm;compound 22 Cu2(mipzhp)2(C104)2-2DMF was monoclinic with space group P2(l)/n and unit-cell parameters of a=l. 1892(7) nm, b= 1.5774(9) nm, c=1.8397(10)nm;compound 25 [Cu2(tpzhp)2Br]Br(CH3OH) was tetragonal with space group 14(1 )/a and unit-cell parameters of a=l. 1987(9) nm, b=l. 1987(9) nm, c=5.424(4) nm. The crystal X-ray analyses show that binuclear copper complexes were obtained between the tridentate N, N, O ligands with pyrazole-1-yl groups and all copper salts are similar at coordination enviro nment. The three-dimensional networks are stabilized by hydrogen bonds and Van de Wall interactions. The compound 25 is a one-dimensional coordination polymer, each ligand bridging two copper atoms and each metal center coordinating four ligands to form a two-strand helical structure.In the four part, four new cyano-bridged complexes were obtained by reaction between two different copper(II) complex and KAg(CN)2-. K2Ni(CN)4 and K3Co(CN)6. The crystal structures of three complexes were determined by single-crystal X-ray diffraction analysis.The unit-cell parameters were listed below: compound [Cu2(dpzhp)2][Ag(CN)2]2 26 was monoclinic with space group P2(l)/c and unit-cell parameters of a=l.05301(9) nm, b=2.06609(18) nm, c=0.82806(7) nm;compound [Cu2(dpzhp)2][Ni(CN)4]-2CH3OH 27 was monoclinic with space group P2(l)/c and unit-cell parameters of a=0.91513(16) nm, b=2.0352(4) nm, c=l. 1330(2) nm;compound [Cu2(dpzhp)2][Ni(CN)4](DMF)-3H2O 29 was triclinic with space group P-l and unit-cell parameters of a=0.9218(2) ran, b=l.0358(3) nm, c=1.3715(4) nm. The crystal X-ray analyses show that the crystal structures of compound 27 and 29 are identical, each copper atom being five-coordinate to furnish a square-pyramidal geometry. Two cyanide groups of each polycyanide anion bridge two [Cu2(dpzhp)2]2+cations alternatively at opposite direction, thus forming a zigzag one-dimensional network. However, in compound 26 only one cyanide group of the Ag(CN)2 link with one [Cu2(dpzhp)2]2+cations and the another one is uncoordinated, thus a hetero-tetranuclear compound was obtained. Magnetic properties of compound 27 and 29 were examined and we find that both of them are anti-ferromagnetic.In this paper, three new tridentate "heteroscorpionate" N,N,0 ligands and their Ni(II)% Pd(II) and Cu(II) complexes were synthesized and characterized. Four new cyanide-bridged complexes were obtained and magnetic properties of two complexes were characterized. These results will provide the theoretical basis for the studies of the properties of this type of ligands and their complexes.