Two- and Three-Dimensional Cadmium Coordination Polymers Based on N,N-(2-Pyridyl)-(4-pyridylmethyl)amine

A new three-dimensional CdII supramolecular framework constructed from the 1-[(1H-tetrazol-5-yl)methyl]-1,4-diazoniabicyclo[2.2.2]octane ligand

A new tetrazole-metal supramolecular compound, di-μ-chlorido-bis(trichlorido{1-[(1H-tetrazol-5-yl-κN(2))methyl]-1,4-diazoniabicyclo[2.2.2]octane}cadmium(II)), [Cd2(C8H16N6)2Cl8], has been synthesized and structurally characterized by single-crystal X-ray diffraction. In the structure, each Cd(II) cation is coordinated by five Cl atoms (two bridging and three terminal) and by one N atom from the 1-[(1H-tetrazol-5-yl)methyl]-1,4-diazoniabicyclo[2.2.2]octane ligand, adopting a slightly distorted octahedral coordination geometry. The bridging bicyclo[2.2.2]octane and chloride ligands link the Cd(II) cations into one-dimensional ribbon-like N-H...Cl hydrogen-bonded chains along the b axis. An extensive hydrogen-bonding network formed by N-H...Cl and C-H...Cl hydrogen bonds, and interchain π-π stacking interactions between adjacent tetrazole rings, consolidate the crystal packing, linking the poymeric chains into a three-dimensional supramolecular network.

Cadmium(ii) complexes containing N,N′-dimethylviolurate as ligand or counteranion: synthesis, characterization, crystal structures and DFT study

The synthesis and X-ray characterization of two N,N′-dimethylvioluric acid (1) derivatives of formula [Cd(DMV)₂(benzim)₂] (2) (benzim = benzimidazole) and [Cd(H₂O)₄(py)₂](DMV)₂ (3) (py = pyridine) are reported.

Synthesis, X-Ray Structure, and Characterization of Catena-bis(benzoate)bis{N,N-bis(2-hydroxyethyl)glycinate}cadmium(II)

The reaction of N, N-bis(2-hydroxyethyl)glycine (bicine; bicH₃) with Cd(O₂CPh)₂ · 2H₂O in MeOH yielded the polymeric compound [Cd₂(O₂CPh)₂(bicH₂)₂]_n(1). The complex crystallizes in the tetragonal space group P4₁2₁2. The lattice constants are a = b = 12.737(5) and c = 18.288(7) Å. The compound contains chains of repeating {Cd₂(O₂CPh)₂(bicH₂)₂} units. One Cd^II atom is coordinated by two carboxylate oxygen, four hydroxyl oxygen, and two nitrogen atoms from two symmetry-related 2.21111 (Harris notation) bicH₂⁻ ligands. The other Cd^II atom is coordinated by six carboxylate oxygen atoms, four from two bicH₂⁻ ligands and two from the monodentate benzoate groups. Each bicinate(-1) ligand chelates the 8-coordinate, square antiprismatic Cd^II atom through one carboxylate oxygen, the nitrogen, and both hydroxyl oxygen atoms and bridges the second, six-coordinate trigonal prismatic Cd^II center through its carboxylate oxygen atoms. Compound 1 is the first structurally characterized cadmium(II) complex containing any anionic form of bicine as ligand. IR data of 1 are discussed in terms of the coordination modes of the ligands and the known structure.

Hydrothermal Syntheses, Crystal Structures, and Characteristics of a Series of Cd−btx Coordination Polymers (btx = 1,4-Bis(triazol-1-ylmethyl)benzene)

Four novel cadmium-btx (btx = 1,4-bis(triazol-1-ylmethyl)benzene) coordination polymers [Cd(btx)(2)(NO(3))(2)](n)(1), [Cd(btx)(2)Cl(2)](n)(2), [Cd(btx)(SO(4))(H(2)O)(2)](n)(3), and [Cd(btx)(S(2)O(7))(H(2)O)](n)(4) have been prepared by hydrothermal reaction (140 or 180 degrees C) and characterized. Both 1 and 2 have two-dimensional rhombohedral grid structures, 3 possesses a two-dimensional rectangular grid structure, and 4 displays a three-dimensional framework, which is formed by btx bridging parallel layers. To the author's best knowledge, polymer 4 is the first Cd(II) polymer in which the Cd(II) ion is eight-coordinated in a hexagonal bipyrimidal geometry. In addition, we studied the effects of temperature on the hydrothermal reaction system of btx and CdSO(4) and found that different products can be obtained at different temperatures. Furthermore, polymer 3 possesses a very strong third-order NLO absorptive effect with an alpha(2) value of 1.15 x 10(-)(9) m W(-1). Polymers 2-4 display strong fluorescent emissions in the solid state at room temperature. The DTA and TGA results of the four polymers are in agreement with the crystal structures.

Novel Triazole-Bridged Cadmium Coordination Polymers Varying from Zero- to Three-Dimensionality

Cadmium salts with different triazole ligands have led to a series of novel triazole-cadmium compounds varying from zero- to three-dimensionality. [Cd(2)(deatrz)(2)(H(2)O)Br(4)] (1) (deatrz = 3,5-diethyl-4-amino-1,2,4-triazole) is a zero-dimensional complex which uses a triazole ligand together with micro-OH(2) as bridges to form a 1D chain via hydrogen-bonding contacts. [[Cd(3)(deatrz)(2)Cl(6)(H(2)O)(2)].2H(2)O](n) (2), [[Cd(dmtrz)Cl(2)].1.5H(2)O](n)(3) (dmtrz = 3,5-dimethyl-1,2,4-triazole), and [[Cd(3)(deatrz)(4)Cl(2)(SCN)(4)].2H(2)O](n)(4) are polymeric 1D chains. 2 and 4 were constructed via trinuclear cadmium units bridged by triazole ligands and chloride atoms, while 3 consists of micro(2)-Cl, micro(3)-Cl, and triazole bridges, cross-linked by hydrogen bonding to give a 3D framework. [[Cd(3)(dmatrz)(4)(SCN)(6)]](n)(5) (dmatrz = 3,5-dimethyl-4-amino-1,2,4-triazole) shows a two-dimensional structure whose fundamental units are trinuclear metal cations bridged via triazole ligands. The complex [[Cd(dmtrz)(SCN)(2)]](n)(6) is the first three-dimensional example in N1,N2-didentate-bridged triazole-metal compounds. Six complexes exhibit six types of bridging modes of N1,N2-triazole in combination with single-atom bridges. 2, 4, and 5 are the unprecedented examples of polymeric chains and planes constructed via trinuclear metal ion clusters, whereas 3 is the first example of the micro(3)-Cl bridging mode in triazole-metal complexes. We have briefly discussed the variety of dimensionalities based on the tuning of different organic ligands and anions.

Self-Assemblies of New Rigid Angular Ligands and Metal Centers toward the Rational Construction and Modification of Novel Coordination Polymer Networks

Self-assemblies of rigid angular ligands with 120 degrees molecular angle and metal centers have been investigated with the aim of achieving the rational construction and modification of coordination polymer structures. The reactions of Co(NCS)(2) with 1,3-bis(trans-4-styrylpyridyl)benzene (L(1)()), 2,6-bis(trans-4-styrylpyridyl)pyridine (L(2)()), 1,3-bis(trans-4-styrylpyrimidyl)benzene (L(3)()), and 1,3-bis(trans-4-styrylquinoly)benzene (L(4)()) afford complexes [Co(L(1)())(2)(NCS)(2)]( infinity ) (1), [Co(L(2)())(2)(NCS)(2)]( infinity ) (2), Co(L(3)())(2)(NCS)(2)(CH(3)OH)(2) (3), and [Co(L(4)())(NCS)(2)]( infinity ) (4), respectively. The resulting complexes exhibit open framework, stairlike hydrogen-bonded chain and single-stranded helical coil structures, which are controlled by the variation of the geometry around the coordination site in ligands. Moreover, the coordination of L(1)() and L(2)() to Mn(hfac)(2) (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate) yields single-stranded helical coordination polymers of [Mn(L(1)())(hfac)(2)]( infinity ) (5) and [Mn(L(2)())(hfac)(2)]( infinity ) (6), respectively.

Two Versatile N,N‘-Bipyridine-Type Ligands for Preparing Organic−Inorganic Coordination Polymers: New Cobalt- and Nickel-Containing Framework Materials

The Schiff base ligands 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene (L1, monoclinic, P2(1)/c, a = 3.856(1) A, b = 11.032(2) A, c = 12.738(3) A, beta = 92.21(3) degrees, Z = 2) and 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene (L2, monoclinic, P2(1)/c, a = 10.885(2) A, b = 4.613(1) A, c = 14.978(3) A, beta = 92.827(4) degrees, Z = 2) were used in the synthesis of four new organic-inorganic coordination polymers, each of them adopting a different structural motif. Synthesis, X-ray structural determinations, and spectroscopic and thermogravimetric analyses are presented. The reaction between Co(NO(3))(2).6H(2)O and L1 afforded a two-dimensional noninterpenetrating brick-wall structure, [Co(C(12)N(4)H(10))(1.5)(NO(3))(2)(H(2)O)(CH(2)Cl(2))(2)](n)() (1, triclinic, P1; a = 10.242(7) A, b = 10.802(7) A, c = 15.100(1) A, alpha = 70.031(1), beta = 75.168(11), gamma = 76.155(11), Z = 2), while Ni(NO(3))(2).6H(2)O combined with L1 yielded an interpenetrating three-dimensional rhombus-grid polymer, [Ni(C(12)N(4)H(10))(2)(NO(3))(2)(OC(4)H(8))(1.66)(H(2)O)(0.33)](n) (2, monoclinic, C2/c; a = 20.815(8) A, b = 23.427(8) A, c = 17.291(6) A, beta = 116.148(6), Z = 8). The reaction of Co(NO(3))(2).6H(2)O and L2 was found to be solvent-sensitive and resulted in the formation of two different noninterpenetrating compounds: [Co(C(14)N(4)H(14))(2)(NO(3))(2)(C(6)H(6))(1.5)](n)() (3, monoclinic, C2/c; a = 22.760(2) A, b = 21.010(3) A, c = 25.521(2) A, beta = 97.151(2), Z = 8), which adopts a two-dimensional square-grid motif formed by propeller-type modules, and [Co(C(14)N(4)H(14))(1.5)(NO(3))(2)(CH(2)Cl(2))(2)](n)() (4, monoclinic, P2(1)/n; a = 14.432(2) A, b = 14.543(8) A, c = 15.448(4) A, beta = 96.968(0), Z = 4), consisting of T-shaped building blocks assembled into a one-dimensional ladder-type structure. These four coordination polymers all exhibit impressive thermal stability. Thermogravimetric studies showed that after complete removal of the solvents, the frameworks are stable to temperatures between 234 degrees C and 260 degrees C.

New inorganic/organic coordination polymers generated from bidentate Schiff-base ligands

The coordination chemistry of the long conjugated bidentate Schiff-base ligands 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (L1) and 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene (L2) with cadmium and cobalt nitrate hydrates is investigated. Four new coordination polymers are prepared by solution reactions and fully characterized by infrared spectroscopy, elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. [Cd(NO3)2(L1)(1.5).0.5(L1)]n (1; monoclinic, P2(1)/c; a = 7.7729(16) A, b = 19.049(4) A, c = 17.865(4) A, beta = 93.13(3) degrees, Z = 4) is obtained by combination of L1 with Cd(NO3)(2).4H2O in a benzene/methanol or THF/methanol mixed-solvent system. The structure features two-dimensional brick wall sheets that are cross-linked by weak noncovalent pi-pi interactions (alternating face-to-face stacking of coordinated and uncoordinated L1 molecules) to generate a novel three-dimensional network. [Co(NO3)2(L1)(1.5).H2O]n (2; orthorhombic, Ccca; a = 19.031(4) A, b = 33.627(7) A, c = 14.299(3) A, Z = 4) is generated from the reaction of L1 with Co(NO3)(2).6H2O in a benzene/ethanol mixed-solvent system. It forms with a unique three-dimensional framework that can be considered a new polymeric motif based on the 1:1.5 metal-to-ligand composition M(L)1.5. The Cd(II) and Co(II) centers in 1 and 2, which lie in seven-coordinate environments, generate two new types of building blocks. The topologies of these two new building blocks are distinctly different from the common "T-shaped" building block generated from the same (MN3O4) coordination environment reported previously. Cd(L2)2(NO3)2 (3) and Co(L2)2(NO3)2 (4) are obtained by combination of L2 with Cd(NO3)(2).4H2O and Co(NO3)(2).6H2O, respectively. Compounds 3 and 4 are isostructural, crystallizing in the monoclinic space group P2(1)/n, with a = 8.5802(17) A, b = 17.506(4) A, c = 10.443(2) A, beta = 96.59(3) degrees, and Z = 2 for 3 and a = 8.5283(17) A, b = 17.408(4) A, c = 10.229(2) A, beta = 97.05(3) degrees, and Z = 2 for 4. 3 and 4 adopt a novel one-dimensional chain structural motif, consisting of M2(L2)2 (M = Cd, Co) ringlike units. O...H-C hydrogen-bonding interactions in both 3 and 4 play a significant role in aligning the polymer strands in the solid state.