Assembly of 1D and 3D cobalt(II) coordination polymers based on isophthalic acid and flexible benzimidazolyl-based ligands

Two new metal–organic coordination polymers {[Co(L1)(nip)]·H₂O} _n (1) and [Co(L2)(ip)] _n (2) (H₂ip = isophthalic acid, L1 = 1,3-bis(benzimidazol-1-ylmethyl)benzene, L2 = 1,4-bis(5-methylbenzimidazol-1-ylmethyl)benzene, H₂nip = 5-nitroisophthalic acid) have been synthesized under hydrothermal conditions and characterized by physicochemical and spectroscopic methods as well as single-crystal X-ray diffraction analysis. The analysis reveals that complex 1 has a 1D double chain structure connected by L1 and nip^2? ligands, which is further assembled into a 3D bbf (moganite network) supermolecular framework via two types of C–H···O hydrogen bond interactions. Complex 2 possesses a 3D MOF with a four-connected cds (CdSO₄ network) topology. The fluorescence and catalytic properties of the complexes for the degradation of Congo red have been investigated.     

Construction of Cd(II)–ferrocenesuccinate coordination complexes via changing adjuvant ligands and anions

Seven Cd(II)–ferrocenesuccinate coordination complexes with the formulas [Cd(η²-FcCOC₂H₄COO)₂(pbbbm)]₂ (1), [Cd(η²-FcCOC₂H₄COO)(pbbbm)Cl]₂ (2), [Cd(η²-FcCOC₂H₄COO)(pbbbm)I]₂ (3), {[Cd(η²-FcCOC₂H₄COO)₂(btx)₂]₂(CH₃OH)_0.5} (4), [Cd(η²-FcCOC₂H₄COO)₂(bix)]₂(H₂O) (5), {[Cd(η²-FcCOC₂H₄COO)(bbbm)_1.5Cl] · (CH₃OH)_0.5}_n (6), and {[Cd(η²-FcCOC₂H₄COO)(mbbbm)Cl] · (H₂O)_2.75}_n (7) [pbbbm = 1,4-Bis(benzimidazole-1-ylmethyl)benzene), btx = 1,4-bis(triazol-1-ylmethyl)benzene), mbbbm = 1,3-bis(benzimidazole-1-ylmethyl)benzene), bix = 1,4-bis(imidazol-1-ylmethyl)benzene, bbbm = 1,1-(1,4-Butanediyl)bis-1H-benzimidazole)] have been synthesized and characterized. Single-crystal X-ray analysis reveals that complexes 1–5 are all dimers and bridged by pbbbm, btx and bix, respectively. But the five complexes present some differences in their dimeric conformations, which can be ascribed to the impacts of adjuvant ligands and counter anions. In contrast to complexes 1–5, both 6 and 7 are of 1-D structures (with the same counter anions), and the former is double ladder-like structure only bridged by bbbm, while the latter is chain-like structure bridged by chlorine anions and adjuvant ligand mbbbm. Notably, various π–π interactions are found in complexes 1–7, and they have significant contributions to molecular self-assembly processes. The electrochemical studies of complexes 1–7 in DMF solution display irreversible redox waves and indicate that the half-wave potentials of the ferrocenyl moieties in these complexes are all shifted to positive potential compared with that of ferrocenesuccinate.     

Two manganese(II) coordination polymers containing semirigid bis(benzimidazole) ligands: synthesis,crystal structures,and catalytic properties

Two ternary mixed Mn(II) coordination polymers (CPs), namely [Mn(L1)(Hnip)₂] _n (1) and [Mn(H_0.5L2)₂(H_1.5btc)₂] _n (2) (H₂nip = 5-nitroisophthalic acid, L1 = 1, 4-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H₃btc = 1,3,5-benzenetricarboxylic acid, L2 = 4,4′-bis(benzimidazol-1-ylmethyl)biphenyl), have been synthesized under hydrothermal conditions and structurally characterized. CP 1 exhibits a non-interpenetrated six-connected pcu framework with the point symbol {4¹²·6³}, while CP 2 features a metal-carboxylate loop-like chain, which is further assembled into a 3D supramolecular network via hydrogen bonds and π–π interactions. The thermal stabilities, luminescence, and catalytic properties of both CPs for the degradation of methyl orange in a Fenton-like reaction have also been investigated.     

One- and two-dimensional cobalt(II) coordination polymers derived from flexible bis(benzimidazole) and aromatic carboxylate co-ligands

Two new coordination polymers, formulated as [Co(L1)(btec)_0.5] _n (1) and {[Co(L2)(bdc)]·H₂O} _n (2) (L1 = 1,3-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H₂bdc = 1,3-benzenedicarboxylic acid, H₄btec = 1,2,4,5-benzenetetracarboxylic acid, L2 = 1,3-bis(benzimidazol-1-ylmethyl)benzene), have been hydrothermally synthesized and characterized by physicochemical and spectroscopic methods as well as single-crystal X-ray diffraction. The cobalt atoms present different environments, with a trigonal pyramidal geometry in 1 and a distorted octahedral configuration in 2. Complex 1 shows a 2D (4,4) network linked by L1 and btec^4? anions, giving an uninodal 4-connected sql topology with a point symbol of {4²·6²}, while complex 2 displays a 1D ladder-like chain structure, which is further assembled into a 3D supramolecular architecture via C–H···π hydrogen bonding interactions. The fluorescence properties of both complexes have been investigated in the solid state.     

Synthesis,crystal structures and photocatalytic properties of four silver(I) coordination polymers based on semirigid bis(pyrazole) and carboxylic acid co-ligands

Four Ag(I) coordination polymers, formulated as [Ag(L1)(tpa)_0.5] _n (1), {[Ag(L2)(ndc)_0.5]·0.5H₂ndc} _n (2), [Ag(L3)_0.5(ndc)_0.5] _n (3) and {[Ag(L3)]·H₃bptc} _n (4) (L1 = 4,4′-bis(pyrazole-1-ylmethyl)-biphenyl, L2 = 4,4′-bis(3,5-dimethylpyrazol-1-ylmethyl)-biphenyl, L3 = 1,4-bis(3,5-dimethylpyrazol-1-ylmethyl)benzene, H₂tpa = terephthalic acid, H₂ndc = 2,6-naphthalenedicarboxylic acid, H₄bptc = 3,3′,4,4′-biphenyltetracarboxylic acid), have been hydrothermally synthesized and structurally characterized. Complex 1 features the rare binodal (4,4)-connected 2D 4,4L10 topological network with a point symbol of {3²·4.6²·7}₂{3²·6²·7²}. Complex 2 has a folded ladder-like chain structure, which is further extended into a 3D supramolecular network via O–H···O hydrogen bonding and π···π stacking interactions. Complexes 3 and 4 both possess 1D zigzag chain structures. Complex 3 is further extended into a binodal (3,4)-connected network with the point symbol of {4.8⁴·10}{6²·8²}₂ by Ag···O weak interactions, while complex 4 is further connected through O–H···O hydrogen bonding and π···π interactions to afford a 2D supramolecular structure. The photoluminescence spectra and photocatalytic properties of these complexes for degradation of methylene blue and methyl orange are reported.     

Two new cadmium(II) coordination polymers with bis(benzimidazole) ligands

Two new cadmium(II) coordination polymers, {[Cd(L1)(tbta)]·H₂O} _n (1) and [Cd(L2)(tbta)] _n (2) (L1 = 1,4-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H₂tbta = tetrabromoterephthalic acid and L2 = 1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene) are obtained under hydrothermal conditions and structurally characterized by single crystal X-ray diffraction methods, IR spectroscopy, TGA and elemental analysis. The L1 and L2 ligands differ by subtle variation of substituents at semi-rigid bis(benzimidazole) bakcbones. Complex 1 features a 3D threefold interpenetrating dia array with a 4-connected 6⁶ topology. Complex 2 displays a 2D {4⁴.6²} sql/Shubnikov tetragonal plane network. Complexes 1 and 2 possess high thermal stabilities and promising fluorescence behavior in the solid state.     

Syntheses,structures, and properties of transition metal coordination polymers based on a long semirigid tetracarboxylic acid and multidentate N-donor ligands

Six transition metal coordination polymers based on a semirigid tetracarboxylic acid and the multidentate N-donor ligands have been synthesized by the hydrothermal method, namely, {[Co(H₂obda) (μ₂-H₂O) (H₂O)₂]·2H₂O}_n (1), {[Co(obda)_0.5(bpe) (H₂O)₂]·3H₂O}_n (2), {[Zn(H₂obda) (H₂O)₄]·H₄obda·6H₂O}_n (3), {[Zn(bpy) (H₂O)₄]·H₂obda}_n (4), {[Ni(bpy) (H₂O)₄]·H₂obda}_n (5) and {[Cu(H₂obda) (bpy)₂]}_n (6) (H₄obda = 1,4-bis(4-oxy-1,2-benzene dicarboxylic acid)benzene, bpe = 1,2-Bis(4-pyridyl)ethylene), bpy = 4,4′-bipyridine). Compounds 1–6 were structurally characterized by the elemental analyses, infrared spectra, and single crystal X-ray diffractions. Compounds 1–2 exhibit the 2D quadrilateral and polygonal layered grid structures, respectively; a 3D supramolecular structure of 2 has been build via π···π and hydrogen bonds interactions. Compounds 3–6 reveal the 1D zigzag and linear chains structures, respectively; furthermore, 3–5 display the diverse 3D supramolecular structures via hydrogen bonds, respectively. The 1-D infinite water chain in 3 has been found between the lattice water molecules. In addition, the thermogravimetric analyses of 1–6, magnetic property of 1, and photoluminescence of 3–4 have been investigated, respectively.     

Silver(I)-organic networks constructed with flexible silver-ethynide supramolecular synthon o-, m-, p-Cl–C6H5OCH2CC⊃Agn (n = 4, 5)

A series of five silver coordination polymers [(AgL1)·(AgCF₃COO)₅·(H₂O)₃] (1), [(AgL1)₂·(AgCF₃COO)₁₁·(H₂O)₆] (2), [(AgL2)·(AgCF₃COO)₃·(H₂O)] (3), [(AgL3)·(AgCF₃COO)₄·(CH₃CN)₂] (4), and [(AgL3)·(AgCF₃COO)₇·(CH₃CN)₂·(H₂O)₂] (5) have been constructed from three flexible anionic ligands HL1, HL2, and HL3 (HL1 = 1-chloro-2-(prop-2-ynyloxy)benzene, HL2 = 1-chloro-3-(prop-2-ynyloxy)benzene, HL3 = 1-chloro-4-(prop-2-ynyloxy)benzene). In these compounds, the invariable appearance of the μ₄- and μ₅-ligation modes of the ethynide moiety affirms the general utility of the flexible silver-ethynide supramolecular synthon o-, m-, p-Cl?C₆H₅OCH₂CC?Ag_n (n = 4, 5) in coordination network assembly. Among them, Ag?Cl interaction plays a vital role in assembling the supramolecular structures in complexes 1?3.     

Synthesis,characterization and property study of new coordination polymers constructed from flexible dicarboxylates and bidentate nitrogen mixed ligands

Five new coordination polymers, [Cd(1,2′-cy)_0.5(bix)H₂O]_n (1), [Cd₂(1,2′-cy)₂(1,10′-phen)₂(H₂O)₂] (2), {[Co(1,2-cy)(2,2′-bipy)(H₂O)₂]·2H₂O}_n (3) {[Cd(succ)(1,10′-phen)H₂O]·H₂O}_n (4), and {[Cd(succ)(2,2′-bipy)H₂O]·2H₂O}_n (5) (1,2-cy = 4-cyclohexene-1,2-dicarboxylate, succ = succinic acid, bix = 1,4-bis(imidazol-1-ylmethyl)benzene, 1,10′-phen = 1,10-phenanthroline, 2,2′-bipy = 2,2′-bipyridine), have been synthesized and characterized by single-crystallographic X-ray diffraction. Complex 1 shows a two-dimensional covalent layer structure. Complex 2 exhibits a two-dimensional supramolecular layer network composed from discrete fundamental units. Complex 3 exhibits a one-dimensional covalent chain-like structure, which further extends to a two-dimensional supramolecular structure with hydrogen bonding and π-π interactions respectively. Complexes 4 and 5 show three-dimensional supramolecular networks composed from one-dimensional chain-like covalent structures. Furthermore, the magnetic property of complex 3 and fluorescent properties of complexes 1, 2, 4 and 5 have also been studied.     

Inhibition of two Cu(II) and Mn(II) coordination polymers on the surgical site infections by inhibiting the bacterial biofilm formation

Within this work, two novel Cu(II) and Mn(II)-based coordination polymers (CPs) along with chemical compositions of {[Cu₂(L¹)(1,4-NDC)₂]·3H₂O}_n (1, 1,4-H₂NDC = Naphthalene-1,4-dicarboxylic acid, L¹ ​= ​di(1H-imidazole-1-yl)methane) and [Mn₃(L²)₂(H₂O)₂(1,4-NDC)₂]_n (2, L² ​= ​1,4-di(1H-imidazole-1-yl)benzene) have been completed in success via related metal salts reaction with 1,4-H₂NDC ligand in existence of various N-donor co-ligands. We discovered its application values on the surgical site infections (SSI) along with corresponding mechanism in the interim. We evaluated inflammatory cytokines released into the urine through ELISA detection kit after compound treatment. Then, we discovered the inhibitory effect of compound on the bacterial biofilm formation via real time RT-PCR.     

Synthesis,crystal structures,luminescence, and photocatalytic properties of two 1D Co(II) coordination polymers constructed with semirigid bis(benzimidazole) and dicarboxylate ligands

Two ternary cobalt(II) coordination polymers (CPs), namely [Co(L1)(npht)] _n (1) and {[Co₂(L2)₂(npht)₂(H₂O)]·H₂O} _n (2) (L1 = 4,4′-bis(benzimidazol-1-ylmethyl)biphenyl, L2 = 1,2-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, and H₂npht = 4-nitrophthalic acid) have been synthesized and structurally characterized by X-ray crystallography. Both CPs feature similar 1D infinite chains containing two distinct loops. CP 1 further forms a 3D supramolecular network via weak C–H···O hydrogen bond interactions. CP 2 shows a 1D two-layer chain structure, assembled through π–π stacking interactions. The electrochemical, luminescence, and photocatalytic activities of the two CPs for the removal of methylene blue under visible or UV light were investigated. Possible photocatalytic mechanisms are discussed.     

Synthesis and characterization of copper(II) and nickel(II) coordination polymers containing 2,6-naphthalenedicarboxylate and bis(benzimidazole) ligands

Two coordination polymers, namely [Ni(L1)-(ndc)(H₂O)] _n (1) and [Cu(L2)_0.5(ndc)] _n (2) (L1 = 1,3-bis(2-methylbenzimidazol-1-ylmethyl)benzene, L2 = 1,4-bis(2-methylbenzimidazole)butane, H₂ndc = 2,6-naphthalenedicarboxylic acid) have been synthesized and characterized by single-crystal and powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and elemental analysis. Complex 1 features a 2D 3-connected hcb network with 6³ topology, which is further extended into a 3D supramolecular framework by O–H···O hydrogen bonding interactions. Complex 2 possesses a 3D threefold interpenetrating (4,5)-connected xah topological network, and its Schläfli symbol is (4².6².8²)(4⁶.6⁴). Both complexes exhibit intense luminescence emissions in the solid state and promising catalytic activities for the degradation of Congo red azo dye in a Fenton-like process.     

New N-heterocyclic carbene mercury(II) complexes: Close mercury-arene interaction

Mononuclear mercury complexes (1, 2, and 3) bearing bis-N-heterocyclic carbene (NHC) ligands of the form [(NHC)₂-μ-Hg]⁺² have been prepared and structurally characterised. The complexes were derived from three bis-imidazolium salts as precursors to NHC; either 1,3-bis(N-methylimidazolium-1-ylmethyl)benzene bis(hexafluorophosphate) (I·2PF₆), 1,3-bis(N-butylimidazolium-1-ylmethyl)benzene bis(hexafluorophosphate) (II·2PF₆) or 3,5-bis(N-butylimidazolium-1-ylmethyl)toluene bis(hexafluorophosphate) (III·2PF₆) treated with mercury(II) acetate. Interestingly X-ray crystal structure analysis revealed a close interaction between the Hg metal centre with one carbon atom of the aryl linker in addition to coordination with two NHCs.     

Structural diversity of copper complexes with angular and linear dipyridyl ligands

The versatile coordination properties of the 2,2′ and 4,4′-long conjugated bidentate ligands 2,5-bis(2-pyridylethynyl)thiophene (L₁), 2,2′-dipyridyldisulfide (L₂) and 4,4′-dipyridyldisulfide (L₃) with copper acetate has been investigated. Reactions with 2,5-bis(2-pyridylethynyl)thiophene (L₁) and 4,4′-dipyridyldisulfide (L₃) leads to two types of complexes. So, when methanol solutions of Cu(OAc)₂ · H₂O were allowed to diffuse into a solution of L₁ or L₃ (ratio 1:1), green crystals of the molecular 1:2 adduct Cu₂(μ-OAc)₄(L₁)₂ (1) and the infinite coordination polymer [Cu₂(μ-OAc)₄(L₃)]_n (2) were obtained. The reaction with L₂, under reflux in MeOH, affords the copper(I) cluster Cu₆(SC₅H₄N)₆ (3) and the dimer [Cu(μ-S)(L₂)]₂ (4). Compound 3 was already known by reaction of the copper(I) salt [Cu(NCMe)₄]PF₆ with SC₅H₄NH in acetone. The structures were determined by X-ray crystallography and their magnetic properties examined.     

Copper(I) complexes of heterocyclic thiourea ligands

The coordination of heterocyclic thiourea ligands (L = N-(2-pyridyl)-N′-phenylthiourea (1), N-(2-pyridyl)-N′-methylthiourea (2), N-(3-pyridyl)-N′-phenylthiourea (3), N-(3-pyridyl)-N′-methylthiourea (4), N-(4-pyridyl)-N′-phenylthiourea (5), N-(2-pyrimidyl)-N′-phenylthiourea (6), N-(2-pyrimidyl)-N′-methylthiourea (7), N-(2-thiazolyl)-N′-methylthiourea (8), N-(2-benzothiazolyl)-N′-methylthiourea (9), N,N′-bis(2-pyridyl)thiourea (10) and N,N′-bis(3-pyridyl)thiourea (11)) with CuX (X = Cl, Br, I, NO₃) has been investigated. CuX:L product stoichiometries of 1:1–1:5 were found, with 1:1 being most common. X-ray structures of four 3-coordinate mononuclear CuXL₂ complexes (CuCl(6)₂, CuCl(7)₂, CuBr(6)₂, and CuBr(9)₂) are reported. In contrast, CuBr(1)₂ is a 1D sulfur-bridged polymer. CuIL structures (L = 7, 8) are 1D chains with corner-sharing Cu₂(μ-I)₂ and Cu₂(μ-S)₂ units, and CuCl(10) is a 2D network having μ-Cl and N-/S-bridging L. Two [CuL₂]NO₃ structures are reported: a mononuclear 4-coordinate copper complex with chelating ligands (L = 10) and a 1D link-chain with N-/S-bridging L (L = 3). Two ligand oxidative cyclizations were encountered during crystallization. CuI crystallized with 6 to produce zigzag ladder polymer [(CuI)₂(12)]·½CH₃CN (12 = N-(pyrimidin-2-yl)benzo[d]thiazol-2-amine) and CuNO₃ crystallized with 10 to form [Cu₂(NO₃)(13)₂(MeCN)]NO₃ (13 = dipyridyltetraazathiapentalene).     

Experimental and theoretical characterization of Co(III) and Zn(II) complexes with phenol-based hexa-dentate macro-acyclic ligands: synthesis,density functional theory and time-dependent density functional theory studies

Macro-acyclic complexes with two dissimilar coordination sites: one includes six coordination set (N₄O₂) and the other a tetradentate donor set (N₂O₂) of the type [Co^IIIL^en]ClO₄ and [Co^IIIL^tn]ClO₄ (where L^en = N,N′-bis(pyridine-2-ylmethyl)-N,N′-bis(5-bromo-3-formyl-2-hydroxybenzyl)-1,2-diaminoethane and L^tn = N,N′-bis(pyridine-2-ylmethyl)-N,N′-bis(5-bromo-3-formyl-2-hydroxybenzyl)-1,3-diaminoepropane) have been synthesized and characterized. Characterization result revealed that in the synthetic procedure of [Co^IIIL^en]ClO₄ only an isomer (trans-pyridine/cis-phenolate) among three possible geometrical isomers is formed. However, synthesis of its counterpart, [Co^IIIL^tn]ClO₄ resulted in the formation of a mixture of geometrical isomers (trans-pyridine/cis-phenolate and cis-pyridine/cis-phenolate). The computational studies of these complexes demonstrated that in [Co^IIIL^tn]⁺ an equilibrium exists between two possible geometrical isomers as result of a small energy difference (0.72 kcal mol^?1), whereas in [Co^IIIL^en]⁺ the difference is (2.71 kcal mol^?1). Furthermore, [Zn^IIL^en] has been studied computationally and experimentally by IR, UV–Vis spectroscopy techniques. The results showed that it has a similar structure to [Co^IIIL^en]⁺ complex. Electronic spectra of the complexes were analyzed and the absorption bands were assigned through the density functional theory (DFT) and time-dependent density functional theory (TD–DFT) studies procedures. The molecular orbital diagrams of the complexes were also determined.     

Cobalt(II) and silver(I) coordination polymers constructed from flexible bis(5,6-dimethylbenzimidazole) and substituted isophthalate co-ligands

Two coordination polymers, [Co(L1)(IPA] _n (1) and {[Ag(L2)(HMIPA)]·H₂O} _n (2) (H₂IPA = isophthalic acid, L1 = 1,2-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H₂MIPA = 5-methylisophthalic acid, L2 = 1,6-bis(5,6-dimethylbenzimidazol-1-yl)hexane, have been synthesized and characterized by physicochemical and spectroscopic methods, as well as single-crystal X-ray diffraction. In 1, six-coordinated cobalt centers are bridged by L1 and IPA^2? ligands to generate a (4,4) two-dimensional layer. However, complex 2 features a 1D chain structure, which is further extended by O–H···O hydrogen bonding interactions into a 2D supramolecular layer with (6³) topology. The fluorescence and thermal gravimetric analysis of both complexes were also explored. Furthermore, the complexes 1 and 2 exhibit remarkable catalytic properties for the degradation of methyl orange dyes in a Fenton-like process.     

Topological diversification of two new Cd(II) photoluminescent coordination polymers via auxiliary N-donor ligands

Two new cadmium(II) coordination polymers, [Cd₂(nda)₂(L₁)] _n (1) and [Cd(nda)(L₂)_0.5] _n (2), were hydrothermally synthesized with 1,4-naphthalenedicarboxylic acid (H₂nda) and auxiliary N-donor coligands [L₁?=?1,5-bis(2-methyl-imidazol-1-yl)pentane and L₂?=?4,4′-bis(2-methyl-imidazol-1-ylmethyl)biphenyl]. Single-crystal X-ray diffraction analyses showed that the topological networks are different when the N-donor ligands are changed. Compound 1 showed a (4¹⁶.6⁵) topology and 2 showed a twofold interpenetrating pcu topology.     

Dinuclear ruthenium(I) complexes of the type [Ru2(CO)4L2] with carboxylate or 2-pyridonate ligands: Evaluation as catalysts for olefin cyclopropanation with diazoacetates

Dinuclear ruthenium(I,I) carboxylate complexes [Ru₂(CO)₄(μ-OOCR)₂]_n (R = CH₃ (1a), C₃H₇ (1b), H (1c), CF₃ (1d)) and 2-pyridonate complex [Ru₂(CO)₄(μ-2-pyridonate)₂]_n (3) catalyze efficiently the cyclopropanation of alkenes with methyl diazoacetate. High yields are obtained with terminal nucleophilic alkenes (styrene, ethyl vinyl ether, α-methylstyrene), medium yields with 1-hexene, cyclohexene, 4,5-dihydrofuran and 2-methyl-2-butene. The E-selectivity of the cyclopropanes obtained from the monosubstituted alkenes and the cycloalkenes decreases in the order 1b > 1a > 1d > 1c. The cyclopropanation of 2-methyl-2-butene is highly syn-selective. Several complexes of the type [Ru₂(CO)₄(μ-L¹)₂]₂ (4) and (5), [Ru₂(CO)₄(μ-L¹)₂L²] (L² = CH₃OH, PPh₃) (6)–(9) and [Ru₂(CO)₄(CH₃CN)₂(μ-L¹)₂] (10) and (11), where L¹ is a 6-chloro- or 6-bromo-2-pyridonate ligand, are also efficient catalysts. Compared with catalyst 3, a halogen substituent at the pyridonate ligand affects the diastereoselectivity of cyclopropanation only slightly.     

Four silver-containing coordination polymers based on bis(imidazole) ligands

Four coordination polymers, [Ag(L¹)](m-Hbdc) (1), [Ag(L¹)]₂(p-bdc)?·?8H₂O (2), [Ag(Hbtc)(L¹)][Ag(L¹)]?·?2H₂O (3) and [Ag₂(L²)₂](OH-bdc)₂?·?4H₂O (4), where L¹?=?1,1′-(1,4-butanediyl)bis(imidazole), L²?=?1,2-bis(imidazol-1-ylmethyl)benzene, m-H₂bdc?=?1,3-benzenedicarboxylic acid, p-H₂bdc?=?1,4-benzenedicarboxylic acid, H₃btc?=?1,3,5-benzenetricarboxylic acid, and OH–H₂bdc?=?5-hydroxisophthalic acid, were synthesized under hydrothermal conditions. Compound 1 contains a–Ag-L¹–Ag-L¹–chain and a hydrogen-bonding interaction induced–(m-Hbdc)-(m-Hbdc)–chain. Compound 2 consists of two independent–Ag-L¹–Ag-L¹–chains. P-bdc anions are not coordinated. Hydrogen bonds form a 3D supramolecular structure. A novel (H₂O)₁₆ cluster is formed by lattice water molecules in 2. Compound 3 contains a–Ag-L¹–Ag-L¹–and a–Ag(Hbtc)-L¹–Ag(Hbtc)-L¹–chain. The packing diagram shows a 2D criss-cross supramolecular structure, with?π?···?π?and C–H ···?π?interactions stabilizing the framework. Compound 4 contains a [Ag₂(L²)₂]²⁺ dimer with hydrogen-bonding,?π?··· π, and Ag ··· O interactions forming a 3D supramolecular framework. The luminescent properties for these compounds in the solid state are discussed.