Studies On The Coordination Compounds Of Several Bridging Ligands

In the last decades, considerable efforts have been made to design and synthesize the molecular-based magnets. Due to their functions to act as the aircraft and magneto-recorded materials, the molecular-based magnets have attracted considerable interest and become one of the subjects of intensive research.In this dissertation, the studies on the coordination fashions of the ligands and the structures of the transition metal complexes with bridging ligands azido anion (N3-) and nitrilotriacetate anion(NTA) have been reviewed in detail. By new routes and improved methods, eight new transition metal complexes of azido anion or the nitrilotriacetate anion (NTA) have been synthesized, and all of them were studied systematically by IR, Elemental Analysis and single crystal X-ray diffraction. The variable-temperature magnetic susceptibility data of several complexes are measured. Studies shows that the synthesized complexes can be divided into dissrete, one-dimensional (1-D),two-dimensional (2-D) and three dimensional (3-D) systems A novel 3-D Co(Ⅱ)-K(Ⅰ) heterometallic complex {[CoK2(NTA)(Hmta)(H2O)3]NO3}n(1)(Hmta = Hexamethylenetetramine) has been synthesized by means of controlling different temperature in different step. The complex crystallizes in the orthorhombic space group P212121 with the cell parameters: a=9.547(1)?, b=14.202(2)?, c=16.626(2)?,V=2254.3(5)?3 and z=4. In this complex, the coordination modes of three carboxylate groups of all NTA are identical, they all act only using one oxygen atom to ligate a pair of K(Ⅰ) ions in a μ1,1-O bridging mode, and using another oxygen atom to coordinate to a Co(Ⅱ) ion. Thus, NTA acts as heterometal and homometal bridges simultaneously, and water only as homometal one. Thecoordinated anions [Co (NTA)(Hmta)]- are assembled into an infinite two-dimensional heterometal network structure by K(Ⅰ) ions. Then, the two-dimensional networks are further extended into an infinite three-dimensional structure by K-O water-K bridges between them. A unique 2-D complex [Cu(ABA)( μ1,1-N3)(H2O)]n(2)(ABA = p-Aminobenzoic acid) has been obtained by adding NaN3 in batches to the reacting system. Complex (2) crystallizes in the triclinic space group Pī with cell parameters: a=7.3631(15)?, b=7.5455(15)?, c=9.3382(19)?,(=95.93(3)3°,( =101.79(3)°, (=117.49(49)°, V=438.69(15)?3 and z=2. The X-ray analysis reveals that the two-dimensional structure is constructed by two kinds of the chains in the complex mutually, one main chain is bridged by the μ1,1-N3 fashion stretches along the c-axis , ABA acts as a bridge between the main chains .The bridging fashion of ABA is that two oxygens of the carboxylate group coordinate to two copper(Ⅱ) ions in one chain and nitrogen of the amino-group to one copper(Ⅱ) ion in another neighboring chain. The main chains construct a perfect two-dimensional layer structure through the special bridging modes, and four different kinds of H-bonds exist between layers. The structure determination of [Mn(N3)( μ1,3-N3) (H2O)3 ]·(Hmta)(3) reveals that the complex crystallizes in the orthorhombic space group P212121 with the cell parameters: a=6.521(1) ?, b=9.325(1)?, c=22.203(6)? , V=1350.0(4) ?3, Dc=1.639Mg/m3, Z=4. The coordination number of Mn(Ⅱ) ion is six, the coordination geometry of Mn(Ⅱ) ion is best described as pseudooctahedral. The two nitrogen atoms of two bridging azide ligands and two oxygen atoms of two water molecules are in the equatorial plane and the nitrogen atom from a azide-unbridging ligand and the oxygen atom of a water molecule occupy the axial positions. Mn(Ⅱ) ions are connected by azido anions through μ1,3-N3- fashion, constructing an infinite 1-D chain. Interestingly, uncoordinated Hmta molecule is inlaid in the "zigzag" chains of the compound.Two new dinuclear complexes [Cu2Na(bipy)3(NTA)(NO3)2(H2O)]·3H2O(4) and [Cu2 (phen)3(NTA)]NO3 ·6H2O(5) containing NTA ligand as well as three mononuclear complexes [Co(bipy)2(N3)2]Cl·2H2O(6), [Ni(bipy)2(N3)2]·H2O(7) and [Cu(phen)2(N3)]NO3·2H2O(8) containi...