Zifeng Li

Versatile coordination patterns in the reaction system of N-benzoyl-N′-(2-pyridyl)thiourea with CuCl2. Their reaction conditions, systematic isolation and crystal structures

A versatile reaction system; N-benzoyl-N′-(2-pyridyl)thiourea (L) with CuCl2, has been studied under conditions of control of the relative concentration of the components (L or CuCl2). Therefore, both converse approaches were employed: one is dropwise addition of L to CuCl2 in ethanol solution, from which a dark-brown needle-like crystal, ∞1{[CuClL′][Cl]} 1, was obtained, which is a chloride-bridged one-dimensional Cu(II) polynuclear complex coordinated by the oxidative cyclization product L′ generated from L (L′ = 2-benzoylimino-[1,2,4]thiadiazolo-[2,3-a]pyridine), and the second approach is conversely dropping CuCl2 into L in acetone solution; at first, a pale-yellow reduced copper(I) mononuclear complex, [CuL2Cl] 2, was formed, which exhibits a planar molecular configuration with a regular three coordination geometry, and then a red bis-sulfur-bridged copper(II) dinuclear complex, {[CuLCl2]2} 3, appeared subsequently. The crystal structures of these three products have been determined by X-ray diffraction. From the presented results the coordination and redox reaction pathways in the L–CuCl2 system have been clearly revealed.

Novel zinc(II) coordination polymers constructed from ferrocenyl carboxylate ligands

Two novel ferrocene-containing Zn(II) coordination polymers, [Zn{μ2-OOCCH(CH3)CFc}2]n [1, Fc = (η5-C5H5)Fe(η5-C5H4)] and {[Zn2{μ2-OOCCH(CH3)CFc}4(bpa)]·2MeOH}n [2, bpa = 1,2-bis(4-pyridyl)ethane], have been prepared. The two polymers have been characterized by single-crystal X-ray crystallography. The Zn(II) ions in polymer 1 are bridged by μ2-coordinated FcC(CH3)CHCOO− anions, forming an infinite [Zn(μ2-OOCH(CH3)CFc}2]n chain. Polymer 2 is constructed from paddle-wheel shaped [Zn2{μ2-OOCCH(CH3)CFc}4] building units. The dimeric tetrabridged cores are connected by organic bridging ligands, leading to a linear [Zn2{μ2-OOCCH(CH3)CFc}4(bpa)]n chain. To the best of our knowledge, 2 is the first example of a Zn(II) polymer built up by ferrocene-based paddle-wheel building units. The electrochemical properties of both polymers were also investigated.

Synthesis, Structures, and Properties of Two Novel Zn(II) Polynuclear Complexes

A tetranuclear complex [Zn4(L)4(μ 2-L)2(OH)2(H2O)6] (1) and a trinuclear complex [Zn3(μ 2-L)6(H2O)2] (2) have been prepared by treatment of HL (HL = 3-(4-carboxyphenylhydrazono)pentane-2,4-dione) with ZnCl2· 2H2O or Zn(NO3)2· 6H2O in methanol solution, respectively. Both molecular structures have been characterized by means of elemental analysis, IR and single crystal X-ray diffraction. Their thermal behaviors and fluorescent properties also have been studied.

An unprecedented 2-D cluster polymer constructed from unique mixed-valence CuI6CuII6 subunits

A new 2-D cluster-based polymer {[Cu(I)(6)Cu(II)(6)L(6)(H(2)O)(3)(CH(3)OH)(6)].5H(2)O.3CH(3)OH}(n) (2) (H(3)L = C(6)H(5)C(O)NHC(S)NHCH(2)COOH) containing unique mixed-valence [Cu(I)(6)Cu(II)(6)L(6)] subunits was synthesized by reaction of single crystals of [Ln(2)(H(2)L)(4)(Phen)(2)(NO(3))(2)] (Ln = Pr (1a), Nd (1b) or Ho (1c)) (Phen = 1,10-phenanthroline) with copper(II) acetate in aqueous DMF. Interestingly, cation-exchanged products {[Cu(I)(6)Cu(II)(5)Zn(H(2)O)(3)(CH(3)OH)(6)].5H(2)O.3CH(3)OH}(n) (3) or {[Cu(I)(6)Cu(II)(4)Co(2)(H(2)O)(3)(CH(3)OH)(6)].5H(2)O.3CH(3)OH}(n) (4) were obtained from single crystals of and the appropriate M(NO(3))(2) (M = Zn or Co) in H(2)O.

Synthesis, structure and electrochemical properties of a zinc(II) coordination polymer based on ferrocenyl-substituted carboxylate and bis (benzimidazolyl)pentane ligands

By reaction of two ligands, Na(o-OOCC6H4COFc) (Fc = (η5–C5H5)Fe(η5–C5H4)) and 1,1′–(1,5–pentamethylene)bis-1H-benzimidazole (pbbm), with Zn(OAc)2 · 2H2O in methanol solution, we have synthesized a zinc(II) coordination polymer [Zn(o-OOCC6H4COFc)2(pbbm)] n . The polymer was characterized by X-ray single crystal diffraction, IR spectroscopy, and elemental analysis. Each Zn atom was connected by two pbbm ligands, leading to an infinite one-dimensional chain. Two monodentate o-FcCOC6H4COO− anions completed the coordination sphere of the central Zn(II) ion. The polymers electrochemical properties were investigated in DMF solution.

A Novel 2D Coordination Polymer Constructed from Left- and Right-handed Helical Chains and 4,4′-bipyridine Bridges

Treatment of 2-methyl-1H-imidazole-4,5-dicarboxylic acid (H3MIA) with Co(NO3)2 in the presence of 4,4′-bipyridine (4,4′-bipy) under hydrothermal condition, yielded one novel two-dimensional (2-D) coordination polymer [Co(HMIA)(H2O)(4,4′-bipy)0.5]·H2On (1). Single-crystal structural study reveals that the complex incorporates alternate left– and right–handed helical chains by 4,4′-bipy linkages. This is the first example of 2-D Co(II) helical coordination polymer with mixed HMIA and 4,4′-bipy ligands. Its thermal properties are also investigated.

Trinuclear and dinuclear Ni(II) complexes constructed by bridging oxygen: crystal structures, magnetic, and thermal properties

The reaction of H2L (N,N ′-bis(5-ethyl-1,3,4-thiadiazol-2-yl)-2,6-pyridinedicarboxamide) with Ni(II) salts gave crystals of two new complexes, [Ni3(µ3-O)(H2L)(L)2] · 2DMF (1) and [Ni2(µ-H2O)(CH3OH)(DMF)(L)2] · H2O · CH3OH (2). The complexes were characterized by elemental analysis, IR, thermal analysis, and X-ray single crystal diffraction. Complex 1 is a trinuclear complex containing a triangle frame in the center formed by three Ni(II) atoms with a bridging µ3-O. Complex 2 is dinuclear formed by two Ni(II) atoms with a bridging H2O. H2L coordinates to metal centers as a pentadentate ligand in 1 and tetradentate in 2. Thermal analysis shows that the thermal stability of 1 is higher than that of 2. In addition, the magnetic properties of 2 are also reported.

Two Novel Lanthanide Coordination Polymers: Synthesis, Structures, Fluorescence, and Thermal Properties

Two novel 1-D chain lanthanide coordination polymers, {[Pr(μ2-L)2(η2-NO3)(CH3OH)(H2O)2]·H2O}n (1) and {[Ho(μ2-L)2(η2-NO3)(CH3OH)(H2O)]·H2O}n (2) (HL = N-benzoyl-N′-(4-benzoxy)thiourea) have been prepared and characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. The fluorescence properties and themostabilities of the two polymers were determined as well.

Hydrothermal Synthesis, Crystal Structure and Thermal Property of a Novel Three-Dimensional Pb(II) Coordination Polymer

One novel Pb(II) coordination polymer formulated as [Pb(4-PyCOO)2]n (1) (Py = C5H4N) has been hydrothermally synthesized. The molecular structure of the polymer has been characterized by elemental analysis, IR and single crystal X-ray diffraction. The complex possesses three-dimensional solid-state structure. The thermal property of the complex has been determined.