Study On Controlled Synthesis, Structures And Property Of D-Block Metal Complexe With Tris(Benzimidazole-2-methyl) Amine As Ligand

Polydentate ligands, containing N-heterocyclics (such as pyrazole, imidazole, and pyrazine, etc.), show a special importance in mimic of biomolecule. More than that, the ligands, when coordinate to metal ions, present a wide variety of coordination modes, so allowing the isolation of a large number of coordination compounds, which are structurally interesting to crystal engineering.In light of the virtues of such ligands, we chosed tris(benzimidazole-2-methyl)amine (NTB) as primary ligand in this synthetic effort, based on which we obtained 12 mono and polynuclear complexes. The work intends to mainly discuss the effects of different reaction conditions on the formation of complexes, for examples, the effect of pH on occurrence and dentation of NTB and the effect of temperature, deprotonation of ligand, difference in second ligands, and presence of anion and solvents on structures of complexes. The complexes obtained are as mono-, or di- or polynuclear, whose structures show the strategic schemes to fabricate the 0D, 1D and 2D metal coordination polymers and so reify the self-assembly of molecular blocks. The originality, shown by these complexes, includes that1,they demonstrated, for the first time, the case of deprotonated NTB, used as ligand for synthesis of coordination compound, and2,they present the first example of NTB as building block of coordination polymer.Now, we intend to introduce the whole of this dissertation by chapters.In Chapter 1, a survey on the categorization, structure domination and potential application of coordination compounds has been made. The significance of tris(benzimidazole-2-methyl)-amine (NTB) ligand in biomimic and the on-going progress of its coordination chemistry are introduced in details, based on which we clarify our attempt to choose this topic.Chapter 2 introduces mainly seven new mononuclear complexes obtained from the ordinary and solvothermal reactions of tris(benzimidazole-2-methyl)amine (NTB) with Ni²⁺,Zn²⁺,Fe²⁺,Cu²⁺ and Cd²⁺ ions. In these products, NTB takes uniformly aκ⁴ -N,N,N, N coordination manner. But for the differences in the electronic configuration and hybridization of metal ions, the compounds present either triangle bipyramidal or square-pyramidal 5-coordination or distorted octahedral 6-coordination. In the lattice packing, owing to the diversity of intermolecular interactions, the complexes appear discrete or bimolecular associated by supramolecular interaction. Especially the comparison between two Cu²⁺ complexes [Cu(H₃L)(SO₄)]·H₂O (4) and [Cu(H₃L)Cl]Cl (5) reveals that anion has an ignorable effect on the structure of complex. Besides, the compounds, [Cd(H₃L)(SO₄)] (6) and {[Cd(H₃L)(SO₄)(H₂O)][Cd(H₃L)(SO₄)]} (7), which were prepared in diversely composed solvents, have respectively 5 and 6-coordinated Cd^â…¡ ions, therewith reifying an effect of solvents on formation of complexes.In Chapter 3, we describe mainly the synthesis and structures of some di-, tri- and polynuclear complexes. The methods used to extend the mononuclear adducts described in chapter 2 include: 1) adding some linking second ligands, such as polycarboxylic acids, cyanide, and sulfate anions, to enable the catenation of consequent complexes. And 2) increasing pH of solution to facilitate deprotonation of NTB to turn it from a pure chelating to a bridging ligand. Obviously the tactics applied are significant to structural crystal engineering and the structures of isolated compounds reflect the conditioned controllability of infinite coordination compounds. There the complexes included are [Zn₂(H₃L)₂(m-BDA)]SO₄ (8) , [Cd₄(H₂L)₂(SO₄)₃]_n (9), [Cu₄(H₂L)(H₃L)(SO₄)₃]_n(10), [(CuCN)₃(H₃L)]_n(11) and [Cu₇(CN)₃(HL)₂]_n(12), of which 8 is a bimetal compound, composed by the linking m-BDC and two identical mononuclear Zn(H₃L) motifs. 9 and 10 are both 2D polymers with cyanide and deprotonated H₂L^- as bridging ligands. Likewise, 11 and 12 are also 2D polymers with partially deprotoned H₂L^- and HL^2- as linking ligands. From the functions of H₂L^- and HL^2-, we see that to tune the structures of complexes through modifying the pH of solution is possible.Chapter 4 summarizes the work involved in this dissertation, telling how to start from NTB, the primary ligand, via controlling the reaction conditions, to tune the structures of coordination compounds from simple to complicated and from zero to high demnsional.