Lanthanide contraction effect on the crystal structures of 2D lanthanide coordination polymers based on 2-(trifluoromethyl)-1<Emphasis Type="Italic">H</Emphasis>-imidazole-4,5-dicarboxylic acid

A series of new two-dimensional (2D) lanthanide(III) coordination polymers, namely {[Ln₂(μ ₂-HTFMIDC)₃(DMA)₄] · 2H₂O} _n [Ln = Pr (1); Nd (2); Sm (3); Eu (4); H₃TFMIDC = 2-(trifluoromethyl)-1H-imidazole-4,5-dicarboxylic acid, DMA = N,N′-dimethylacetamide] for type I and {[Ln₂(μ ₂-HTFMIDC)₃(DMA)₂(H₂O)₂] · DMA} _n [Ln = Eu (5); Gd (6)] for type II, have been successfully prepared under solvothermal conditions and structurally characterized for the first time. Both two types of structures exhibit similar 2D honeycomb-like networks, which are constructed by the linkages of μ ₂-HTFMIDC^2? bis-(bidentate) bridging ligands and Ln(III) metal centers. However, slightly different ABAB stacking fashions of the 2D layers and distinctly different hydrogen bonding interactions between the neighboring 2D layers are observed in crystal structures of type I and type II, which may be attributed to the lanthanide contraction effect. Meanwhile, the solid-state luminescent properties of 4 and 5 have been also investigated.     

Interaction of hydantoins with transition metal ions: synthesis,structural, spectroscopic,thermal and magnetic properties of [M(H<Subscript>2</Subscript>O)<Subscript>4</Subscript>(phenytoinate)<Subscript>2</Subscript>] M = Ni(II), Co(II)

Complexes of Ni(II) and Co(II) of the formulae [Ni(H₂O)₄(pht)₂] (1) and [Co(H₂O)₄(pht)₂]·1,5NH₃·H₂O (2) (where pht = phenotoinate anion) were obtained and characterized physicochemically. [Ni(H₂O)₄(pht)₂] (1) crystallizes in a monoclinic space group P2₁/c; a = 11.7358(8), b = 11,1250(8), 11.4182(7) Å; β = 97.076(5)°; V = 1479.41 Å³; Z = 2. The environment around the nickel and cobalt ions can be described as a distorted octahedron. The metal ion was found to bind to four water molecules and two nitrogen atoms derived from two anions of the monodentate phenytoinate. Four intramolecular hydrogen bonds designated as S(6) graph set are found in one [Ni(H₂O)₄(pht)₂] (1) molecule. Two chain HB patterns, constructed by the [Ni(H₂O)₄(pht)₂] molecules extending along the c and b axes, respectively, have been observed. The cobalt complex precipitates with the additional solvent molecules: one and a half of ammonia and one water. The results document the preferential binding of hydantoins to the metal ions through N(3) atom.     

Structures and enhanced third-order nonlinear optical performance of four complexes investigated by thin film <Emphasis Type="Italic">Z-</Emphasis>scan technique

Four transition metal complexes have been synthesized via hydrothermal reactions, namely, [Zn(1,3-BIB)(CH₃COO)₂]₂ 1, [Cu₂(1,4-BIB)₃(CO₃)₂](1,4-BIB)·10H₂O 2, {[Mn(H₂O)₂(1,2-BIB)₂]Cl₂}_n 3, and {[Mn(1,2-BIB)(1,4-NDC)]₂}_n 4, where 1,n-BIB = 1,n-bis(imidazol-l-yl-methyl)benzene, n = 2, 3, 4 and 1,4-NDC = naphthalene-1,4-dicarboxylic acid. Complex 1 presents a discrete ring-like structure. Complex 2 shows a ladder-like chain structure, while complex 3 has a joint-like chain structure. Complex 4 features a layer structure constructed from [Mn₂(N₄O₈)] clusters. The third-order nonlinear optical (NLO) properties of these complexes in thin films have been investigated by employing the Z-scan technique. Complexes 1–3 exhibit strong third-order NLO reverse-saturable absorption, while 4 shows third-order NLO saturable absorption and a strong self-defocusing effect. The third-order NLO susceptibilities χ ⁽³⁾ of the four complexes were calculated as 2.74 × 10^?9, 12.24 × 10^?9, 42.78 × 10^?9 and 189.32 × 10^?9 esu, respectively. The electronic structures of the complexes were investigated by density functional theory, and the origins of their NLO properties are discussed.     

A series of 3d metal complexes prepared by in situ reactions of a flexible diacylhydrazine ligand: synthesis,structures and magnetic properties

The coordination reactions of 3d metal salts with malonic acid N,N′-bis(salicyloyl) bishydrazide (H₆mbshz) afforded three complexes, namely [Cu₂(H₂bshz)(Py)₄Cl₂]·Py (1) (Py = pyridine), [Fe₂(bshz)(Py)₂] (2) and the known complex [Ni₄(aehba)₂(DMF)₂(H₂O)₂]·2DMF (3), where bshz = N,N′-bis(salicyloyl)hydrazine anion and aehba^4? = azo-enolic-2-hydroxybenzamide anion. The X-ray crystal structures of all three complexes have been obtained. Complexes 1 and 2 are composed of N–N-bridged binuclear units, while complex 3 displays a planar tetranuclear structure in which four Ni(II) centers are linked together by N–N and N=N bonds. The bshz anions in 1 and 2 and aehba^4? anions in 3 were all generated in situ from H₆mbshz. A mechanism for these reactions is proposed, involving tandem C–N cleavage and C–N/N–N coupling processes via free radical intermediates. Magnetic investigations revealed dominant antiferromagnetic interactions between the metallic centers of each complex.     

Substituted group-directed assembly of six coordination compounds based on pyrazole bifunctional ligands

Six new complexes [Mn₈(μ₄-O)₄(phpz)₈(MeOH)₄]·(MeOH)(H₂O) (1) [Co₂(HphpzH)(Hphpz)₂(phpz)₂]·4(MeOH) (2), Ni(Hphpz)₂ (3), [Ni(Hphpz)₂]·H₂O (4), [Zn₄(pzpy)₄Cl₄] (5) and [Cu₂(pzpy)₂(HCO₂)₂(H₂O)₂] (6) have been synthesized by hydrothermal reactions of MCl₂·4H₂O (M = Mn, Co, Ni, Zn or Cu) with 5-(2-hydroxyphenyl)-3-pyrazole (HphpzH) or 2-(1H-pyrazol-3-yl)pyridine (Hpzpy). The complexes were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Complex 1 is an octanuclear Mn(III) cluster, complexes 2 and 6 are binuclear Co(III) and Cu(II), respectively, complexes 3 and 4 are isomorphous mononuclear species, while complex 5 is a tetranuclear Zn(II) cluster. The magnetic behavior of complex 1 was investigated. Magnetic susceptibility measurements revealed antiferromagnetic exchange interactions between the metal centers in the clusters. The luminescence properties of the complexes were investigated at room temperature in the solid state.     

Hydrostable coordination polymers of a methyl-functionalized 4,4′-bipyridine ligand: structure,stability, magnetic and luminescent properties

The reactions of aromatic dicarboxylic acids and methyl-functionalized 4,4′-bipyridine ligands with metal salts under hydrothermal conditions generated four structurally diverse cobalt(II), zinc(II) and cadmium(II) coordination polymers, [Co(CH₃-BDC)(dmbpy)_0.5] _n (1), [Cd(OH-HBDC)₂(dmbpy)] _n (2), [Zn(NDC)(dmbpy)] _n , (3) and {[Cd(DBA)(dmbpy)_0.5]·2H₂O} _n (4) (CH₃–H₂BDC = 5-methylisophthalic acid, OH–H₂BDC = 5-hydroxyisophthalic acid, H₂NDC = 1,4-naphthalenedicarboxylic acid, H₂DBA = 4,4′-methylenedibenzoic acid, dmbpy = 2,2′-dimethyl-4,4′-bipyridine). All four complexes have been structurally characterized by X-ray crystallography. Complex 1 shows a 3D jsm topology structure with two 1D channels parallel to the a and b axes. Complex 2 has a zigzag chain in which the OH-HBDC ligands point alternately up and down. Complexes 3 and 4 show 2D (4,4) networks when the dinuclear metal centers and their ligands are regarded as nodes and linkers, respectively. Complex 3 also shows twofold interpenetration with 1D channels along the b axis. Two nets of complex 4 interlock in parallel, giving rise to a polycatenated layer (2D → 2D). Thermogravimetric and chemical stabilities, magnetic and luminescent properties of these complexes were investigated.     

Silver-based coordination complexes of carboxylate ligands: crystal structures,luminescence and photocatalytic properties

The complexes [Ag₄(dpe)₄]·(btec) (1) and [Ag₄(bpy)₄]·(btec)·12H₂O (2) (dpe = 1,2-di(4-pyridyl)ethylene, bpy = 4,4′-bipyridine, H₄btec = 1,2,4,5-benzenetetracarboxylic acid) have been synthesized in aqueous alcohol/ammonia by slow evaporation at room temperature and characterized by elemental analysis, single-crystal X-ray diffraction, FTIR, UV–Vis and luminescence spectroscopies. Both complexes are composed of 1D infinite cationic [Ag/dpe(bpy)] _n ⁿ⁺ chains and discrete btec^4? anions. Their three-dimensional supramolecular structures are built up of cationic sheets formed from [Ag/dpe(bpy)] _n ⁿ⁺ units via weak Ag…Ag and Ag…N interactions, plus anionic btec^4? sheets featuring electrostatic, π–π and hydrogen bonding interactions. Both complexes exhibited photocatalytic activity for the decomposition of methyl orange under UV light irradiation.     

Synthesis,crystal structures,and antibacterial studies of silver(I) complexes with reduced Schiff base amino acid ligands

Three Ag(I) complexes of reduced Schiff base amino acid ligands, [Ag₂(Hshis)₂]·3H₂O (1), Ag(Hcgly) (2), and Ag(cala) (3) (H₂shis = N-(2-hydroxybenzyl)-l-histidine, H₂cgly = N-(2-hydroxy-5-chlorobenzyl)-glycine, Hcala = N-(4-chlorobenzyl)-d,l-alanine), have been synthesized and characterized by X-ray crystallography. Complex 1 shows a dimeric structure, while complex 2 shows one-dimensional zigzag chains, which are extended into a two-dimensional supramolecular sheet by hydrogen bonds. Complex 3 exhibits a 2D sheet structure with dangling arms. The antimicrobial activities of the complexes have been investigated.     

Directed assembly of cobalt(II) 1-H-indazole-3-carboxylic acid coordination networks by bipyridine and its derivatives: structural versatility,electrochemical properties,and antifungal activity

This paper describes the hydrothermal synthesis, full characterization, and architectural diversity of three intriguingly bioactive cobalt–organic frameworks, namely, 3D [Co(HL ^? )₂(BPY)] _n ·4nH₂O (1), 2D [Co(HL ^? )₂(BPE)] _n (2), and 2D [Co(HL ^? )₂(DPP)] _n (3) coordination polymers, synthesized through a mixed ligand strategy using H ₂ L (1-H-indazole-3-carboxylic acid) as a main structural block and the flexible bipyridine and its derivatives (BPY = 4,4′-bipydine, BPE = 1,2-bis(4-pyridyl)ethane, DPP = 1,3-bis(4-pyridyl)propane) as auxiliary ligand sources. Complexes 1–3 were isolated as air stable and slightly soluble crystalline solids and characterized using elemental analysis, FT-IR, electrochemical technique, thermogravimetric analysis, powder X-ray diffractometer, and single-crystal X-ray crystallography. The bipyridine derivatives played key roles in defining the structural space group and dimensionality feature of the obtained networks. The abundant H-bonding and π–π stacking interactions in complexes 1–3 gave rise to their intricate metal–organic structures of 3D (1), 2D (2), and 2D (3). In addition, the solutions of complexes 1–3 showed profound antifungal activities against the selected strain of Colletotrichum musae compared with the controlled group using benomyl as a traditional agrochemical fungicide.     

Crystal structure,spectroscopic and thermal properties of copper(II) and manganese(II) coordination polymers based on triazole-benzoic acid ligands

Two transition metal coordination polymers {[Cu(tba)₂(H₂O)]·2H₂O} _n (1) and {[Mn(Htta)₂(H₂O)₂]·2H₂O} _n (2) {Htba = 3-[1,2,4]triazol-1-yl-benzoic acid, H₂tta = 2-[1,2,4]triazol-1-yl-terephthalic acid} have been synthesized under solvothermal conditions. Both complexes have been characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis and FTIR spectroscopy. Complex 1 has a 1-D chain structure in which Cu(II) atoms are doubly bridged by tba^? ligands, which is further stabilized by hydrogen bonding and π–π stacking interactions to give a 3-D supramolecular framework. In complex 2, Mn(II) atoms are doubly bridged by Htta^? ligands to form 1-D chains, which are further connected by intermolecular hydrogen bonds to form a 3-D supramolecular framework. The electronic spectra and thermal behaviors of complexes 1 and 2 are also reported.     

Synthesis,structures and magnetic properties of four 3D heterometallic cobalt(II)–barium(II) coordination polymers

Four heterometallic complexes, namely {[CoBa(2,5-pdc)₂(H₂O)₃]_n·2nH₂O} (1), [CoBa(2,5-pdc)₂(H₂O)₄]_n (2), [CoBa(2,5-pdc)₂(H₂O)₅]_n (3) and [CoBa₂(2,5-pdc)₃(μ₂-H₂O)₂(H₂O)₄]_n (4) (2,5-H₂pdc?=?pyridine-2,5-dicarboxylic acid), have been hydrothermally synthesized and characterized both structurally and magnetically. All four complexes exhibit 3D frameworks, in which the Co(II) centers are chelated by pyridine nitrogen and carboxyl oxygen atoms in a five-membered ring. The Ba(II) centers are chelated and bridged by carboxyl oxygen atoms to extend the structures into 3D frameworks. The networks of the complexes can be controlled via rationally choosing the appropriate ligand and tuning the ratio of the two types of metal centers. The magnetic properties of complexes 1, 2 and 4 have been investigated from 2 to 300 K.     

Two New Cubane-Type Tetranuclear Compounds of Copper(II), Nickel(II) Derived from Reduced Schiff Base Ligand: Syntheses,Structures and Magnetic Properties

Two tetranuclear complexes, [M(H₃L)]₄·X (1, M = Cu, X = 4,4′-dpdo; 2, M = Ni, X = DMF, H₅L = 2-[(3,5-dibromo-2-hydroxybenzyl) amino]-2-(hydroxymethyl)propane-1,3-diol, 4,4′-dpdo is 4,4′-bipyridine-N,N′-dioxide, DMF = N,N′-dimethyl formamide), have been synthesized and characterized by elemental analysis, IR and X-ray single-crystal diffraction. Compound 1 features a centrosymmetric tetranuclear copper cluster which further constructed a 1D chain through a tetra-acceptor hydrogen bonds of 4,4′-dpdo molecule. Compound 2 having a P2₁ /n space group also exhibits a tetranuclear nickel cluster with a cubane topology in which the central Ni(II) ion and oxygen atoms from H₃L^2? occupy the alternate vertices of the cube. Magnetic properties of 1 and 2 in the 2–300 K have also been discussed. The tetranuclear cubanes cores display dominant ferromagnetic interactions.     

Synthesis and catalytic activity of rhenium carbonyl complexes containing alkyl-substituted tetramethylcyclopentadienyl ligands

A series of six alkyl-substituted tetramethylcyclopentadienyl mononuclear metal carbonyl complexes [(η ⁵-C₅Me₄R)Re(CO)₃] [R = allyl (1), i-Pr (2), n-butyl (3), t-butyl (4), benzyl (5), CH(CH₂)₄ (6)] have been synthesized by treating the corresponding ligands (C₅Me₄R) [R = allyl, i-Pr, n-butyl, t-butyl, benzyl, CH(CH₂)₄] with Re₂(CO)₁₀ in refluxing xylene. The six new complexes were characterized by elemental analysis, IR, ¹H NMR and ¹³C NMR spectroscopy. The crystal structures of all six complexes were determined by X-ray crystal diffraction analysis, showing that they have similar molecular structures, being mononuclear carbonyl complexes. In each of these complexes, the Re atom is η ⁵ -coordinated to the cyclopentadienyl ring. Complexes 1–5 have significant catalytic activity in Friedel–Crafts reactions of aromatic compounds with alkylation reagents. Compared with traditional catalysts, these mononuclear rhenium carbonyl complexes have obvious advantages such as lower amounts of catalyst, mild reaction conditions and environmentally friendly chemistry.     

A New Three-Dimensional Framework Based on K<Subscript>2</Subscript>Zr<Subscript>3</Subscript>-Substituted Sandwich-Type Polyoxometalate Clusters and K–O Chains

A new Zr-substituted sandwich-type polyoxometalate, H₈K₃[Zr₃K₂(μ₃-O)₂(μ₂-OH)(H₂O)₂(A-α-PW₉O₃₄)₂]·2Cl^?·7H₂O (1), has been made under hydrothermal conditions. 1 was characterized by IR spectrum, thermogravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction, respectively. Crystal data for 1: tetragonal space group P4₂2₁2, a = 24.0096(3), b = 24.0096(3), c = 14.7416(3) Å, V = 8498.0(2) Å³ and Z = 4. Single crystal X-ray structure analysis reveals that 1 exhibits a three-dimensional framework structure based on Zr₃K₂-substituted sandwich-type polyanions [Zr₃K₂(μ₃-O)₂(μ₂-OH)(H₂O)₂(PW₉O₃₄)₂]^9? linked by K–O chains. UV–Vis spectrum indicates that 1 is a wide-gap semiconductor. In addition, the SHG of 1 was also investigated.     

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.     

Synthesis and characterization of half-sandwich ruthenium(II) complexes with N-alkyl pyridyl-imine ligands and their application in transfer hydrogenation of ketones

A series of new arene ruthenium(II) complexes were prepared by reaction of ruthenium(II) precursors of the general formula [(η⁶-arene)Ru(μ-Cl)Cl]₂ with N,N′-bidentate pyridyl-imine ligands to form complexes of the type [(η⁶-arene)RuCl(C₅H₄N-2-CH=N-R)]PF₆, with arene = C₆H₆, R = iso-propyl (1a), tert-butyl (1b), cyclohexyl (1c), cyclopentyl (1d) and n-butyl (1e); arene = p-cymene, R = iso-propyl (2a), tert-butyl (2b). The complexes were fully characterized by ¹H NMR and ¹³C NMR, UV–Vis and IR spectroscopies, elemental analyses, and the single-crystal X-ray structures of 2a and 2b have been determined. The single-crystal molecular structure revealed both compounds with a pseudo-octahedral geometry around the Ru(II) center, normally referred to as a piano stool conformation, with the pyridyl-imine as a bidentate N,N ligand. The activity of all complexes in the transfer hydrogenation of cyclohexanone in the presence of NaOH and iso-propanol is reported, the compounds showing turnover numbers of close to 1990 and high conversions. Complex 2b was also shown to be very effective for a range of aliphatic and cyclic ketones, giving conversions of up to 100 %.     

Syntheses,characterization, and magnetic properties of two 3D frl topological frameworks constructed from nickel diphosphonates

Two 3D open-framework nickel diphosphonates, [Ni₃(H₂zdn)₂(bpe)₂]·4H₂O (1) and [Ni₃(H₂zdn)₂(bpy)₂]·bpy·4H₂O (2) (H₅zdn = zoledronic acid, bpe = trans-4,4-vinylenedipyridine, bpy = 4,4′-dipyridyl), have been prepared and structurally characterized. In complex 1, the metal centers are linked by zoledronate ligands to generate a 2D layer, containing 14- and 24-membered rings. These 2D layers are further pillared by the bpe ligands into a 3D network structure with cylindrical channels. Magnetic susceptibility measurements reveal ferrimagnetism at T _c = 3.8 and 4.4 K for complexes 1 and 2, respectively.     

Synthesis and catalytic reactivity of mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes

The reactions of five dinuclear carbonyl complexes [(η ⁵-C₅Me₄R)Mo(CO)₃]₂ [R = allyl, ⁿ Bu, ^t Bu, Ph, Bz] with I₂ in chloroform solution gave the corresponding mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes [(η ⁵-C₅Me₄R)MoI(CO)₃] [R = allyl (1), ⁿ Bu (2), ^t Bu (3), Ph (4), Bz (5)]. The molecular structures of complexes 2, 3 and 5 were determined by X-ray diffraction analysis. The results show that the substituent in the ring can directly affect the Mo–I bond distances; the more sterically hindered the substituent, the longer the Mo–I bond. Friedel–Crafts reactions of aromatic compounds with a variety of alkylation reagents catalyzed by the complexes showed that all of these mononuclear molybdenum carbonyl complexes have catalytic activity in Friedel–Crafts alkylation reactions. Indeed, compared with traditional catalysts, these mononuclear metal carbonyl complexes have obvious advantages such as higher activities, mild reaction conditions, high selectivity, simple post-processing, and environmentally friendly chemistry.     

Addition of Pt(IPr) Groupings to Ru<Subscript>5</Subscript> Carbide Gives New Mixed-Metal Pt–Ru Cluster Complexes

The reaction of Pt(IPr)(SnBu ₃ ^t )(H), 1 [IPr = N-heterocylic carbene ligand N,N ′-bis-(2,6-(diisopropyl) phenyl)imidazol-2-ylidene] with Ru₅(μ ₅ -C)(CO)₁₅, 2, in 1.2:1 (and 2.2:1) ratio in benzene solvent at refluxing temperature afforded the octahedral monoplatinum–pentaruthenium cluster complexes PtRu₅(IPr)(CO)₁₅(μ ₆ -C), 3 in 54 % (10 %) yield, PtRu₅(IPr)(CO)₁₄(H)₂(μ ₆ -C), 4 in 6 % (10 %) yield and the diplatinum–pentaruthenium cluster complex Pt₂Ru₅(IPr)₂(CO)₁₅(μ ₆ -C), 5 in 2 % (36 %)yield. Complex 3 readily reacts with H₂ at room temperature to give complex 4. Compound 5 exhibits dynamical activity in solution where the two Pt(IPr) groups are exchanging rapidly. All three compounds were structurally characterized by single-crystal X-ray diffraction analyses.