Syntheses, Structures And Properties Of Coordination Compounds Containing N-Heterocyclic Multidentate Ligands

Considerable efforts are being undertaken to generate multi-dimensional coordination polymers due to their intriguing structural diversities and their potential applications in various advanced materials. The N-containing heterocyclic ligands, 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine (bdmpp) and 1H-1,2,3-triazole-4,5-dicarboxylic acid (H3tda), were chosen in this dissertation to prepare coordination oligomers and polymers through precursor method and hydro-/solvo- thermal methods. The results were summarized as follows:1. 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine (bdmpp) was used to synthesize the transition metal compounds that possess at least one of the following requirements. Firstly, that some ligands around the metal center are labile and be readily replaced by other strong donor ligands. Secondly, that some ligands in the compounds are potential multi-linkers to interconnect with other metal centers. Thirdly, that the coordination is around metal center unsaturated. Such compounds are the potential precursors to generate coordination oligomers and polymers.2. Reactions of three Cu(II) compounds of 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine (bdmpp), [Cu(bdmpp)(MeCN)2][ClO4]2 (2), [Cu(bdmpp)(N3)2]·1.5H2O (8) and [Cu(bdmpp)(N3)(μ-N3)]2·2MeOH (9) with 4,4′-bipy, dicyanamide (dca), azide, or M2+ (M = Cu, Co, Ni) produced a series of homo- and hetero-metallic coordination oligomers and polymers {[Cu(bdmpp)(ClO4)]2(μ-4,4′-bipy)}[ClO4]2 (18), {[Cu(bdmpp)(μ-dca)][ClO4]}n (19), {[Cu(bdmpp)(μ-N3)][ClO4]?MeCN}n (20), {[Cu(bdmpp)(μ-ClO4)][PF6]?(MeCN)}n (21),[Cu(N3)(bdmpp)]2(μ-N3)2Cu(N3)2 (22)和{[Cu(μ-N3)(bdmpp)(μ-N3)M(μ-N3)(X)]2·eMeCN}n (23:M = Co,X = N3,,e = 0;24:M = Ni,X = Cl;e = 4). Compounds 18~24 have been characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray crystallography. Compound 18 has a centrosymmetric dimeric dication structure in which two [Cu(bdmpp)(ClO4)]+ fragments are bridged by one 4,4′-bipy. Compound 19, 20 or 21 has a 1D linear or spiral chain extending along the b-axis in which each [Cu(bdmpp)]2+ fragment links its equivalent ones via bridging dca, azide or perchlorate anions, respectively. Compound 22 has a trinuclear sandwich structure in which two molecules of 8 link a Cu(N3)2 species via two end-on bridging azide anions. Compounds 23 and 24 have a 1D chain structure extending along the c axis in which [Cu(μ-N3)(bdmpp)(μ-N3)M(μ-N3)(X)]2 (M = Co, Ni) molecules are linked by end-to-end azide anions (23) or end-on azide anions (24). In addition, the electrochemical properties of 18~24 and their precurcors 2, 8 and 9 in DMF were also investigated by cyclic voltammetry.3. Three new compounds, [Cu(bdmpm)2][PF6] (25) [bdmpm = bis(3,5-dimethyl-N-pyrazolyl) methane], [Cu(μ-bdmpp)(MeCN)]2[PF6]2 (26) and [Ag(μ-bdmpp)NO3]2 (27) [bdmpp = 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine], were prepared directly by metal salts and ligands. X-ray analysis revealed that compounds 26 and 27 are metal ion-induced double-stranded helicates that are bridged by the twisted bdmpp ligands. Compounds 25 and 26 were employed as catalysts in the ATRP of MMA in cyclohexanone, while compound 27 failed to work in the polymerization of MMA even using initiator. Though MMA was polymerized in the presence of compounds 25 and 26, as well as initiator (EBiB), it did not belong to the system of ATRP. The effects of the polymerization temperature and the various ratios of MMA to Cu(I), as well as solvent were investigated in details only in the presence of compound 25 or 26 as catalysts.4. The solvothermal method was employed to prepare a novel copper(I) coordination polymer, {[Cu(tpt)(MeCN)][ClO4]}∞(28) [tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine]. Single crystal X-ray diffraction showed that the compound 28 consists of a 2D (3,4)-connected network with a unique (53)2(5482) topology. The luminescent properties of compound 28 in the solid state at ambient temperature were investigated.5. Five novel cadmium(II)/Htda, zinc(II)/tda and Cu(II)/phen(bpy)/Htda coordination polymer [K2Cd(Htda)2]n (29) (H3tda = 1-H-1,2,3-triazole-4,5-dicarboxylate), [Zn2(bpy)2(tda)NO3·0.5H2O]n (30) (bpy = 2,2′-bipyridine), [Cu(phen)(Htda)] (31), [Cu(bpy)(Htda)] (blue)(32) (phen = 1,10-phenanthroline) and [Cu(bpy)(Htda)] (light blue) (33) were prepared through solvothermal methods and structurally characterized. An X-ray analysis revealed that 29 consists of an unusual 3D (4,4,6)-connected network with a (4264)Cd(42638)K(4361082)Htda topology; compound 30 is a 1D chain structure and then connected byπ···πinteraction between auxiliary ligand of bpys to form a 3D net. The luminescent properties of compounds 29 and 30 along with the H3tda ligand in the solid state were investigated. Compound 31 or 33 has a 1D spiral chain structure and compound 32 has a 1D stair-like chain structure, and their electronic properties were determined by cyclic voltammetry.