Syntheses, Structures And Characterization Of Transition Metal Complexes Of Arenesulfonates And Polyamines

Current efforts on hybrid metal-organic complexes are directed mostly toward synthesis of diverse metal-organic frameworks using polycarboxylates and phosphonates. However, a few of studies are dedicated to the metal arenesulfonates owing to the weak coordination ability of sulfonate toward transition metal ions. In addition, the transition metal complexes with imidazole and organic polyamines have received considerable attention in recent years because of their diverse biological activity and excellent catalytic properties. In this paper, we discuss mainly the syntheses and coordination behavior of transition metal cations toward arenedisulfonates and organic polyamines.(1) Three new polymeric complexes{[Zn(1,5-nds)(Him)₂(H₂O)]·2H₂O}_n (1), {[Cd₂ (1,5-nds)₂(Him)₄(H₂O)₂]·4H₂O}_n (2) and [Mn(1,5-nds)(Him)₄]_N (3) were prepared by the reactions of 1,5- naphthalenedisulfonate (1,5-nds) with zinc oxide, cadmium oxide, manganese carbonate and imidazole in aqueous solution, respectively. X-ray diffraction analysis reveals that complex 1 and 2 have the similar two-dimensional layer network structures. In complex 1, the -SO₃^- groups of the 1,5-nds ligand have two different coordination modes, one bridges two Zn atoms in a bidentate fashion with the shortest Zn…Zn distance being 0.54523(16) nm (0.54533(9) nm for Cd…Cd in 2), the ligand acts as aμ₄ bridge and links four symmetry-related Zn centers forming a linear chains with the shortest Zn…Zn distance between Zn atoms separated by a 1,5-nds ligand being 1.02530(22) nm(1.02570(11) nm for Cd…Cd in 2), while the other coordinates to the Zn atom in a monodentate fashion, the ligand acts as aμ₂ bridge and links the adjacent chains giving rise to a 2-dimensional network with the shortest Zn…Zn distance 0.8017(2) nm (0.80194(22) nm for Cd…Cd in 2). The overall structure can be described as stacking of 2-dimensional networks, held together by inter-layered hydrogen bonds between water molecules and SO₃^-groups. In complex 3, Mn(â…¡) ion is coordinated in a distorted octahedral geometry. The [Mn(Him)₄]²⁺ units are linked by 1,5-nds which act as bidentate bridging ligands, leading to the forming of a 1-D Zig-Zag chain coordination polymer with Mn…Mn distance 1.14499(12) nm. There are significant inter-string hydrogen bonded interactions. Therefore, the 1,5-nds ligands have much stronger coordination ability to Zn(â…¡), Cd(â…¡) and Mn(â…¡) in aqueous solution by introducing imidazole ligand as auxiliaries to these metal centers. The theoretical investigation of the complexes 1-3 as a structure unit were carried out with Gaussian 03W and MOPAC 2007 program packages, and the single-point energy, atomic charges distribution, bond order and composition of some frontier molecular orbitals were also discussed. Their properties were also characterized by element analysis, IR,¹H NMR and TG analysis.(2) Complexes [Cu(Him)₂(H₂O)₄](1,5-nds) (4), [Co(Him)₂(H₂O)₄](1,5-nds) (5) and [Zn (C₆H₈N₂)₃(H₂O)](C₇H₇SO₃)₂·3H₂O (6) hvae been synthesized and characterized by elemental analysis, IR , ¹H NMR spectroscopies, and X-ray single-crystal diffraction analysis. The complexes 4 and 5 own the same structure type. There is no direct coordination between SO₃^-and Cu²⁺ and Co²⁺ in the presence of water molecules and imidazole ligand, instead, hydrogen bonding interactions between SO₃^- and imidazole and water molecules constructed two-dimensional alternating inorganic-organic structures. Therefore, the Cu²⁺ and Co²⁺ show no tendency to coordinate to sulfonate anions in the presence of imidazole ligand in aqueous solution. p-Toluenesulfonate in complex 6 didn't coordinate to Zn²⁺ in the presence of o-phenylenediamine. All of the SO₃^- O-atoms and the amino H-atoms, water molecules are involved in hydrogen bonds with each other, resulting extended stable structures.(3) A novel one-dimensional zinc(â…¡) coordination polymer [Zn(acac)₂(4,4'-bipy)]_n (7) has been synthesized and cultured using the solvothermal method in methanol medium. It's structure was characterized by element analysis, IR, ¹H NMR and TGA. The crystal structure was determined by X-ray single-crystal diffraction. In the crystal, a plannar structure unit Cu(acac)₂ are linked with 4,4'-bipyridinyl, forming a one-dimension chain. The theoretical investigation of the complex 7 as a structure unit was carried out at HF/LanL2dz level with Gaussian 03W program, and the atomic charges distribution, composition of some frontier molecular orbitals provided a good testimony for the coordination condition in the crystal structure.(4) Three new zinc complexes [(tren)Zn(HCOO)Zn(tren)](BF₄)₃(8), [(tren)ZnCl]BF₄(9) and [Zn(1,2-pn)3](ClO₄)₂(10) were obtained by the reactions of zinc salts with polyamine tris (2-aminoethyl)amine, propane-1,2-diamine respectively. X-ray diffraction analysis reveals that in complex 8 and 9, Zn(â…¡) ion is coordinated in a distorted trigonal bipyramids coordination geometry, while in complex 10 Zn(â…¡) ion adopts octahedral coordination geometry. There is moderate intermolecular hydrogen bonds between the amino hydrogens and BF₄^- fluorins in complex 8, forming 3-D layer structure. Compounds 8-10 were also characterized by element analysis, IR and H NMR.(5) Three new complexes [Ni(C₇H₁₉N₃O)₂](ClO₄)₂(11), [Cd(C₇H₁₉N₃O)₂](ClO₄)₂(12) and {[Cu₂(C₇H₁₉N₃O)₂(C₁₀H₈N₂)](ClO₄)₄·H₂0}(13) have been prepared by reaction of ligand l-[bis(aminoethyl)amino]-2-propanol (L) and 4,4'-bipyridyl with Ni(â…¡), Cd(â…¡) and Cu(â…¡) ions. The products were characterized by element analysis, IR, H NMR , TGA and X-ray single-crystal diffraction analysis. In compound 11, the nickel center coordinates to two tridentate nitrogen atoms of two L ligands, leaving the other binding site hydroxypropyl pendant. Ni(â…¡) ion with two L ligands forms six-coordinated complex . The geometry around Ni(â…¡) is octahedral. The L in compound 12 is coordinated to Cd(â…¡) ions as tetradentate mode, so that the Cd center is eight-coordinated. This is not a familiar coordination number for the Cd(â…¡) ion. Eight coordination atoms form a distorted square antiprism with a Cd(â…¡) ion center. Compound 13 is a binuclear mixed-ligand copper(â…¡) complex with 4,4'-bipyridyl as bridging ligand. Each of Cu(â…¡) ions is bonded to three nitrogen atoms and one oxygen atom from L and one nitrogen atom from 4,4'-bipy, forming a CUN₄O five-coordinated tetragonal pyramid stereochemistry. The Cu…Cu distance in [Cu₂ (C₇H₁₉N₃O)₂(C₁₀H₈N₂)]⁴⁺ is 1.1122 nm. Thermogravimetric analysis (TGA) was performed to investigate the thermal stability of compounds 11-13. The thermal behaviour of 11 and 13 is very similar and generally shows a single-step explosive thermal decomposition at 298℃and 260℃. The results provide the valuable information for further investigations for these compounds as a potential energetic materials.