Coordination compounds of nickel with trithiocyanuric acid. Part II. Crystal and molecular structure of [Ni(taa)(ttcH)] (taa=tris-(2-aminoethyl)amine,ttcH3=trithiocyanuric acid)

Coordination compounds of compositions [Ni(taa) (ttcH)] (1), [Ni(teta)(ttcH)] (2), [Ni(sper)(ttcH)]·5H2O (3), [Ni(chxn)2(ttcH)] (4) and [Ni(1,3-pn)(ttcH)(H2O)] (5), where taa=tris-(2-aminoethyl)-amine, ttcH3= trithiocyanuric acid [1,3,5-triazine-2,4,6-trithione], teta=triethylenetetramine, sper= spermine [(N,N-bis-(3-aminopropyl)-1,4-butanediamine], chxn=trans-1,2-diaminocyclohexane, 1,3-pn=1,3-diaminopropane, (the ligands are depicted in Scheme 1) have been prepared and characterized by C, H, N, S analysis, i.r. and u.v.-vis. spectroscopies and magnetochemical measurements. Those complexes containing water were also studied by thermal analysis. X-ray analysis of [Ni-(taa)(ttcH)] revealed a trigonal bipyramidal geometry around the NiII centre, which can be increased to octahedral by a non-bonding interaction between Ni and the S atom of the trithiocyanuric dianion [Ni—S(3)= 2.6650(10) Å].     

Coordination compounds of nickel with trithiocyanuric acid. Part IV. Structure of [Ni(pmdien)(ttcH)] (pmdien = N,N,N′,N′,N′′-pentamethyldiethylenetriamine,ttcH3 = trithiocyanuric acid)

Ni^II mixed-ligand complexes of compositions [Ni(pmdien)(ttcH)] (1), [Ni(baphen)₂(ttcH)] · 4H₂O (2), [Ni-(dpa)(ttcH)(H₂O)] (3), [Ni(cyclam)(ttcH)] · 2H₂O (4), [Ni(hexaa)](ttcH) (5) and [Ni(hexab)(ttcH)] · 2H₂O (6), (baphen = 4,7-diphenyl-1,10-phenanthroline, dpa = 2,2-dipyridylamine, cyclam = 1,4,8,11-tetraazacyclotetradecane, hexaa = 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1^6,9]-octadecane, hexab = 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane) have been prepared and characterized by means of i.r., u.v.–vis. spectroscopies and magnetochemical measurements. The redox properties of the complexes were studied by cyclic voltammetry. The crystal and molecular structure of [Ni(pmdien)(ttcH)] was determined. The nickel atom is penta-coordinated by three N atoms of pmdien, and by S and N atoms of trithiocyanurate(2–) anion.     

Reactions of bis(isopropylxanthato)nickel(II) with nitrogen-donor ligands—II

New complexes of bivalent nickel with isopropylxanthates and nitrogen-donor ligands of composition [Ni(Prⁱxa)₂(L)], [Ni(Prⁱxa)₂(L¹)₂], [Ni(L²)₂](Prⁱxa)₂, and [Ni(L³)₃] (Prⁱxa)₂ have been synthesized, where Prⁱxa = i-C₃H₇OCS₂⁻, L = 1,2-diaminopropane (1,2-pn), N,N,N′,N′=tetramethylethylenediamine (tmen) or 4,4′-bipyridine (4,4′-bipy), L¹ = pyridine (py), L² = diethylenetriamine (dien) and L³ = ethylenediamine (en), 1,2-diaminopropane or 1,10-phenanthroline (phen). The compounds have been characterized by elemental analysis, IR and UV-vis spectroscopy, magnetochemical measurements, molar conductivity and thermal analysis. The compounds containing the complex cation have been one-electron irreversibly oxidized using cyclic voltammetry. The crystal and molecular structures of [Ni(Prⁱxa)₂(tmen)] and [Ni(phen)₃](Prⁱxa)₂ have been elucidated.     

Supramolecular Assemblies of Mononuclear and Polymeric Nickel(II) Glutarato Complexes via π‐π Stacking Interactions and Hydrogen Bonds: [Ni(H2O)3(phen)(C5H6O4)] · H2O and [Ni(H2O)2(phen)(C5H6O4)]

Syntheses of the sky blue complex compounds [Ni(H₂O)₃(phen)(C₅H₆O₄)] · H₂O ( 1 ) and [Ni(H₂O)₂(phen)(C₅H₆O₄)] ( 2 ) were carried out by the reactions of 1,10‐phenanthroline monohydrate, glutaric acid, NiSO₄ · 6 H₂O and Na₂CO₃ in CH₃OH/H₂O at pH = 6.9 and 7.5, respectively. The crystal structure of 1 (P 1 (no. 2), a = 14.289 Å, b = 15.182 Å, c = 15.913 Å, α = 67.108°, β = 87.27°, γ = 68.216°, V = 2934.2 ų, Z = 2) consists of hydrogen bonded [Ni(H₂O)₃‐ (phen)(C₅H₆O₄)]₂ dimers and H₂O molecules. The Ni atoms are octahedrally coordinated by two N atoms of one phen ligand, three water O atoms and one carboxyl O atom from one monodentate glutarato ligand (d(Ni–N) = 2.086, 2.090 Å; d(Ni–O) = 2.064–2.079 Å). Through the π‐π stacking interactions and intermolecular hydrogen bonds, the dimers are assembled to form 2 D layers parallel to (0 1 1). The crystal structure of 2 (P2₁/n (no. 14), a = 7.574 Å, b = 11.938 Å, c = 18.817 Å, β = 98.48°, V = 1682.8 ų, Z = 4) contains [Ni(H₂O)₂(phen)(C₅H₆O₄)_2/2] supramolecular chains extending along [010]. The Ni atoms are octahedrally coordinated by two N atoms of one phen ligand, two water O atoms and two carboxyl O atoms from different bis‐monodentate glutarato ligands with d(Ni–N) = 2.082, 2.105 Å and d(Ni–O) = 2.059–2.087 Å. The supramolecular chains are assembled into a 3 D network by π‐π stacking interactions and interchain hydrogen bonds. A TG/DTA of 2 shows two endothermic effects at 132 °C and 390 °C corresponding to the complete dehydration and the lost of phen.     

Planar Ni(II) 1,2-dithiolenes involving bidentate N -donor ligands

A series of planar Ni(II) dithiolenes derived from maleonitriledithiole (mnt), benzene-1,2-dithiole (bdt) and 1-toluene-3,4-dithiole (tdt) with bidentate N,N-ligands (bpy = 2,2′-bipyridine; phen = 1,10-phenanthroline, nphen = 5-nitro-1,10-phenanthroline) of the [Ni(N,N)(dithiol)] type have been synthesized. The compounds have been characterized by elemental analysis, IR and electronic spectroscopies, magnetochemical and conductivity measurements. Single crystal X-ray analysis of [Ni(phen)(bdt)] confirmed a planar geometry of NiN₂S₂. Possible practical applications such as use for vulcanization catalytic agents and for their anticholinesterase activity were evaluated.     

Heterometallic Polynuclear Complexes of Macrocyclic ­Oxamide with Pyrazine‐2, 3‐dicarboxylic Acid: Synthesis,Crystal Structure,and Magnetic Properties

Three novel complexes, namely [Zn(CuL)(pzdc)]₂ · 5H₂O ( 1 ), [Zn(NiL)(pzdc)]₂ · 5H₂O ( 2 ), and [Gd₂(pzdc)₂(NiL)₆](ClO₄)₂ · 6H₂O ( 3 ) (CuL and NiL, H₂L = 2, 3‐dioxo‐5, 6, 14, 15‐dibenzo‐1, 4, 8, 12‐tetraazacyclo‐pentadeca‐7, 13‐dien and H₂pzdc = pyrazine‐2, 3‐dicarboxylic acid) were synthesized and structurally determined. Complexes 1 and 2 are tetranuclear [Zn^II₂M^II₂] (M = Ni ( 1 ), Cu ( 2 ), respectively) molecules including both oxamide and pzdc^2– bridges. The structure of compound 3 consists of pyrazine‐2, 3‐dicarboxylate and oxamido‐bridged, and is arranged in different butterfly‐like octanuclear molecules. The magnetic susceptibility data of 3 were analyzed.     

Synthesis,structures and thermal properties of Cu(II) and Ni(II) complexes containing diethylenetriamine and nicotinate ligands

The syntheses and crystal structures of four new divalent transition metal complexes of the types [Cu₂(dien)₂(nic)](ClO₄)₃ · MeOH (nic = anion of nicotinic acid; dien = diethylenetriamine), 1; [Cu(dien)(nic)]₂(nic)₂, 2; [Cu(dien)(nic)]₂(BF₄)₂ · 2MeOH, 3 and [Ni(dien)(nic)(H₂O)]₄(NO₃)₄ · 2MeOH, 4, are reported, which were prepared by the reactions of diethylenetriamine and nicotinic acid with Cu(ClO₄)₂ · 6H₂O, Cu(OAc)₂ · H₂O, Cu(BF₄)₂ · 6H₂O and Ni(NO₃)₂ · 6H₂O in MeOH, respectively. These complexes were characterized by single-crystal X-ray diffraction method and elemental analyses. In the cation of complex 1, one nicotinate ligand bridges two Cu(II) metal centers through the pyridyl nitrogen atom and one of the carboxylate oxygen atoms. The cations of complexes 2 and 3 form the twelve-membered metallocycles, involving two Cu(II) ions that are bridged by two nicotinate ligands. The cation of complex 4 forms a tetranuclear cage with the four Ni(II) metal centers bridged by four nicotinate ligands and each Ni(II) metal center adopts the distorted octahedral geometry. Their thermal properties have been investigated by using differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA).     

Synthesis,characterization and screening of biological activity of Zn(II), Fe(II) and Mn(II) complexes with trithiocyanuric acid

New Zn(II), Fe(II) and Mn(II) complexes with a combination of nitrogen-donor ligands and trithiocyanuric acid (ttcH₃) were prepared and characterized by elemental analysis, IR and UV–Vis spectroscopies. The antitumor activity of the prepared complexes, together with already known Ni(II) species, were assayed in vitro against G-361 (human malignant melanoma), HOS (human osteogenic sarcoma), K-562 (human chronic myelogenous leukaemia) and MCF-7 (human breast adenocarcinoma) tumor cell lines. The IC₅₀ values of the Fe(II) and Mn(II) compounds turned out to be lower than those of cisplatin and oxaliplatin. The antimicrobial activities were evaluated by MIC against bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis). The molecular structure of [Zn(taa)(ttcH)] · H₂O (taa = tris(2-aminoethyl)amine) was determined by X-ray diffraction. The central atom is pentacoordinated by four N atoms of taa and one N atom of the ttcH dianion.     

Preparation and structures of a series of phosphorus‐free Nickel(II) diamine complexes and their applications in hydrogenation of acetophenone

To develop economical and phosphorus‐free catalysts for hydrogenation of ketones, three new complexes, [Ni(1R,2R‐dpen)₂(H₂O)Cl]₂Cl₂· 2Et₂O (1), [Ni(1R,2R‐dpen)(phen)(CH₃OH)₂]Cl₂·2CH₃OH (2) and [Ni(1,8‐dan)₂(DMF)Cl]₂Cl₂· 3H₂O (3), and three reported compounds, [Ni(opda)(phen)Cl₂]·CH₃OH (4), [Ni(opda)₂Cl₂] (5) and [Ni(1,2‐dach)₂]Cl₂ (6), were prepared and the structures of new compounds were determined by single crystal X‐ray diffraction analysis, in which 1R,2R‐dpen, phen, 1,8‐dan, opda and 1,2‐dach denote 1R,2R‐1,2‐diphenylethylenediamine, 1,10‐phenanthroline, 1,8‐diaminonaphthalene, o‐phenylenediamine and 1,2‐diaminocyclohexane, respectively. The catalytic effects for hydrogenation of acetophenone of these compounds were tested. This revealed very poor or no catalytic effects of these complexes in transfer hydrogenation of acetophenone using isopropanol or HCOOH? NEt₃ as hydrogen source. However, they presented much better catalytic effects in ionic hydrogenation of acetophenone using H₂ gas as hydrogen source with a dependence of the catalytic effects on the base used in the hydrogenation reactions. The complexes represent a kind of green hydrogenation catalyst, although the conversion in the hydrogenation reactions is not as high as expected. Copyright © 2010 John Wiley & Sons, Ltd.     

Novel Copper(II) Thiodibenzoic Acid Coordination Polymers by in situ Extrusion of Sulfur from 2,2′‐Dithiodibenzoic Acid and the Unique Oxidation of Disulfide to Sulfate

Slow diffusion reaction of 2,2′‐dithiodibenzoic acid (dtdb) with CuCl₂ in the presence of N‐donor ligands results in the formation of different coordination polymers where both S–S and C–S scission and oxidation of S is observed. X‐ray diffraction analysis of [Cu(tdb)(phen)(H₂O)]₂ · 2H₂O.2DMF] ( 1 ), [Cu(tdb)(py)₂(H₂O)]₂ ( 3 ), and [Cu(tdb)(bipy)(H₂O)]₂ · 0.5H₂O ( 4 ) (tdb = thiodibenzoic acid, phen = phenanthroline, py = pyridine, bipy = 2,2′‐bipyridine) show that the metal ions are coordinated to the carboxylate oxygen atoms of the in situ generated tdb ligand in a monodenate fashion. In [Cu(phen)(SO₄)₂(H₂O)₂]_n ( 2 ) and [Cu(bipy)(SO₄)₂(H₂O)₂]_n ( 5 ), the sulfur is oxidized to sulfate ions prior to coordination with the metal. Complex 1 has a dimeric structure with π–π interactions between the phen ligands, whereas 3 and 4 form 1D polymeric chains.     

Syntheses and photocatalytic performances of four coordination complexes constructed from 1,10-phenanthroline and polycarboxylic acids

Four coordination complexes of copper(II) and iron(II), namely [CuCl(phen)₂](5-NO₂-Hipa)·2H₂O (BUC-10), [Cu(phen)(3,4-H₂dczpb)(H₂O)]·H₂O (BUC-11), [Fe(phen)(L)(H₂O)]₂ (BUC-12), and [Fe(phen)₃](3,4-H₃dczpb)₂·0.6H₂O (BUC-13) (phen = 1,10-phenanthroline; 5-NO₂-H₂ipa = 5-nitroisophthalic acid; 3,4-H₄dczpb = 3,4-dicarboxyl-(3′,4′-dicarboxylazophenyl) benzene; L = 6,12-dihydroxy-1,2,6,12-tetrahydroindazolo[2,1-a]indazole-1,7-dicarboxylic acid), have been synthesized under hydrothermal conditions. All four complexes were characterized by single-crystal X-ray diffraction, FTIR, elemental analysis and UV–Vis diffuse reflection spectroscopy. The photocatalytic performances of the complexes for decomposition of methylene blue under UV irradiation were also investigated.     

Formation and Structural Characterization of Metal Complexes derived from Thiosalicylic Acid

The formation and structural aspects of some metal complexes of thiosalicylic acid (TSA) were studied. The μ‐bridging tetra‐coordinated Ru complex, [Ru(C₆H₄(CO₂)(μ‐S)(H₂O)]₂ ( 1 ) was formed by hydrothermal reaction of TSA with RuCl₃. The complexes [M(dtdb)(phen)(H₂O)]_n ( 2 – 4 ) (M = Zn^II, Co^II, Ni^II, dtdb = 2,2′‐dithiodibenzoate anion, phen = 1,10‐phenanthroline) were obtained by the slow diffusion technique and the in situ S–S bond formation was confirmed by elemental, spectral and X‐ray analysis. Reaction of TSA with CuCl₂ and 2,2′‐bipyridine (bipy) under the slow diffusion technique yielded the dimer [Cu(tdb)(bipy)] ( 5 ) (tdb = thiodibenzoic acid), where the in situ generation of 2,2′‐thiodibenzoic acid was observed.     

Tetrathiomolybdates of nickel

Summary The complexes [Ni(en)₃]MoS₄, [Ni(dien)₂]MoS₄ and [Ni(phen)₂(MoS₄)]·2H₂O (en = ethylenediamine, dien = diethylenetriamine, phen = 1,10-phenanthroline) were prepared. On the basis of their magnetochemical and spectral properties the compounds can be characterized as octahedral nickel(II) complexes. The complexes were also studied by c.v. Chemical oxidation of [Ni(en)₃]MoS₄ affords [Ni(en)MoS₄]₂SO₄; this complex has been characterized by i.r. and e.p.r. spectroscopy and by magnetic measurements.     

Copper(II) complexes with 1,2,4-triazolo[1,5-a] pyrimidine and its 5,7-dimethyl derivative

Several Cu(II) complexes with 1,2,4-triazolo[1,5-a]pyrimidine (tp) and its 5,7-dimethyl derivative (dmtp) have been isolated and structurally characterized. Five of them are mononuclear and contain 1,10-phenanthroline (phen) or ethylenediamine (en) as auxiliary ligands, their formula being [Cu(H₂O)(phen)(tp)₂](ClO₄)₂ · H₂O, [Cu(H₂O)(phen)(dmtp)₂](ClO₄)₂, [Cu(NO₃)(H₂O)(phen)(tp)](NO₃), [Cu(H₂O)₂(en)(tp)₂](ClO₄)₂ and [Cu(H₂O)₂(en)(dmtp)₂](ClO₄)₂. In all these compounds the tp or dmtp ligand is monodentately coordinated via the nitrogen atom in position 3. The auxiliary ligand influences the coordination number, which is five when this ligand is phen and six when it is en whereas the number of triazolopyrimidine ligands linked to the metal seems to be influenced by the nature of the counteranion. A dinuclear compound with tp has also been isolated, its formula being [Cu₂(OH)(H₂O)_2.5(tp)₅](ClO₄)₃·(H₂O)_1.5, with both metal atoms linked by an hydroxydo group and by a tp bridging ligand, coordinated to one of the copper atoms via N3 and to the other via N4. This compound has several unusual features among the metal complexes with triazolopyrimidine derivatives: the presence of two different kinds of bridging moieties, the coexistence of bridging and terminal ligands and the formation of a N3–N4 bridge for a Cu(II) dinuclear compound for a derivative without exocyclic oxygen atoms.     

New s-block complexes of 1,10-phenanthroline and 1,3-benzothizole-2-thiolate inhibit urease in silico and in vitro

The coordination chemistry of 1,10-phenanthroline (phen) and sodium 1,3-benzothiazole-2-thiolate (SBT) with selected s-block elements has been investigated. Four metal complexes were prepared and their structures were characterized using a variety of analytical techniques including infrared, UV–visible, ¹H NMR and ¹³C NMR spectroscopies, elemental analysis, mass spectrometry and single-crystal X-ray diffraction. The reactions of phen and SBT with M(X)_n (M = K(I), Cs(I), Mg(II), Sr(II); X = OH⁻, CO₃⁻, Cl⁻; n = 1, 2) in MeOH–H₂O yielded one-dimensional chains of both potassium [K₂(phen)₂(BT)₂(H₂O)₄]_n ( 1 ) and caesium [Cs(phen)(BS)(H₂O)]_n ( 2 ) (where BT = 1,3-benzthiazole-2-thiolate and BS = 1,3-benzthiazole-2-sulfinothiolate) and mononuclear complexes of both magnesium {[Mg(phen)(H₂O)₄](BT)₂·phen} ( 3 ) and strontium {[Sr(phen)₂(H₂O)₄](BT)₂} ( 4 ). In these complexes, phen binds via an N,N′ chelate pocket, while the monoanonic BT⁻ ligands either coordinate in a bidentate fashion (in the case of 1 ) or remain uncoordinated (in the case of 3 and 4 ). In complex 2 , SBT ligand was oxidized in situ into a new BS ligand. The sulfinothiolate oxygen atoms in BS coordinate with caesium in a tridentate fashion. Complexes 1 – 4 were evaluated against urease for enzyme inhibition. The complexes displayed significant inhibition with IC₅₀ values in the range 10.8–45.8 μM. In order to examine the structure–activity relationship, the complexes were docked at the active site of urease. Docking results clearly demonstrate the binding of each complex within the active site of the enzyme.     

Solid state thermal isomerisation of diethylenetriamine complexes of NiX2 (X=NO3, ClO4, BF4 and CF3SO3)

Summary [Ni(dien)₂]X₂·nH₂O (dien=diethylenetriamine; n=0, X=NO₃ or CF₃SO₃; n=0.5, X=ClO₄ or BF₄ and n=2, X=CF₃SO₃) complexes have been prepared and investigated thermally in the solid state. [Ni(dien)₂](NO₃)₂ (1) and [Ni(dien)₂](CF₃SO₃)₂ (2) undergo endothermic irreversible phase transitions (209–247°C and 184–205°C; H=5.6 kJ mol^–1 and 7.7 kJ mol^–1 for (1) and (2), respectively). [Ni(dien)₂](ClO₄)₂·0.5H₂O (3) shows an endothermic irreversible phase transition after deaquation (201–216°C; H=7.7 kJ mol^–1). [Ni(dien)₂](BF₄)₂·0.5H₂O also shows an endothermic irreversible phase transition after deaquation, accompanied by partial decomposition. All the complexes possess octahedral geometry with the ligands arranged meridionally. The phase transitions are explained in terms of conformational changes of the triamine chelate rings.Author to whom all correspondence should be directed. Supplementary data available: i.r. spectra (Table 4) and x-ray diffraction patterns (Table 5).     

Mixed‐Ligand Complexes of Copper(II) with α‐Hydroxycarboxylic Acids and 1,10‐Phenanthroline

Eight new two‐ligand complexes of copper(II) with 1,10‐phenanthroline and one of four different α‐hydroxy‐carboxylic acids (glycolic, lactic, mandelic and benzylic) were prepared. The complexes of general formula [Cu(HL)₂(phen)] · nH₂O (HL = monodeprotonated acid) ( 1 – 4 ) were characterized by elemental analysis, IR, electronic and EPR spectroscopy, magnetic measurements and thermo‐gravimetric analysis. The complexes of general formulae [Cu(HL)(phen)₂](HL) · H₂L · nSolv [ 1 a (HL = HGLYO^–, n = 1, Solv = MeCN) and 3 a (HL = HMANO^–, n = 0)] and [Cu(L)(phen)(OH₂)] · nH₂O [ 2 a (L = LACO^2–, n = 4) and 4 a (L = BENO^2–, n = 2)] were characterized by X‐ray diffractometry. In all these latter a pentacoordinated copper atom has a basically square pyramidal coordination polyhedron, the distortion of which towards a trigonal bipyramidal configuration has been evaluated in terms of the parameter τ. In 1 a and 3 a there are three forms of α‐hydroxycarboxylic acid: a monodentate monoanion, a monoanionic counterion, and a neutral molecule lying in the outer coordination sphere; in 2 a and 4 a the α‐hydroxycarboxylic acid is a bidentate dianion coordinating through carboxyl and hydroxyl oxygens.     

Synthesis,spectral and magnetic properties,and crystal structures of copper(II)2-methylthionicotinate adducts with chelating ligands

The synthesis and characterization of [Cu₂(2-MeSnic)₄(H₂O)₂], [Cu(2-MeSnic)₂(en)], [Cu(en)₂(H₂O)₂](2-MeSnic)₂ and [Cu(dien)(H₂O)₂](2-MeSnic)₂ (where 2-MeSnic=2-methylthionicotinate, en=ethylenediamine, dien=diethylenetriamine) is reported. The characterizations were based on elemental analysis, infrared, electronic and EPR spectra, and magnetic susceptibility measurements over a temperature range of 1.9–300 K. The available evidence supports a dimeric structure for [Cu₂(2-MeSnic)₄(H₂O)₂] and for [Cu(en)₂(H₂O)₂](2-MeSnic)₂ a tetragonal-bipyramidal environment about the copper(II) atom. The other two complexes were studied also by X-ray analysis. The [Cu(dien)(H₂O)₂](2-MeSnic)₂ crystallizes in the monoclinic system. The copper(II) atom has a square-pyramidal arrangement, with three nitrogen atoms of the tridentate diethylenetriamine and one water molecule in the base of the pyramid, and the remaining water molecule occupies the apical position. The copper(II) atom deviates from the basal plane by 0.1164(5) Å toward the water molecule in the apical position. The copper(II) atom in [Cu(2-MeSnic)₂(en)] is coordinated by two symmetry-dependent nitrogen atoms of ethylenediamine and by two pairs of non-equivalently coordinated carboxyl oxygen atoms of two symmetry-dependent 2-methylthionicotinates with CuO bond distances of 1.975(2) and 2.564(2) Å, respectively, resulting in a highly distorted tetragonal-bipyramidal coordination.     

Hydrothermal synthesis and crystal structure of a novel 2-D polymeric manganese (II) complex with mixed ligands

A novel polymeric complex, [Mn(phen)(pdc)]_∞ (phen=1,10-phenanthroline, H₂pdc=2,5-pyridinedicarboxylic acid) has been synthesized from the hydrothermal reaction system of H₂pdc, phen, MnO₂, and H₂O. [Mn(phen)(pdc)]_∞ is characteristic of an edge-sharing dinuclear Mn^II structure unit bridged by pdc, leading to a 2-D framework whose stacking is based on weak H-bond interaction. The temperature dependence of the magnetic susceptibility for [Mn(phen)(pdc)]_∞ indicates antiferromagnetic coupling [J = −2.76(4) cm⁻¹] between the adjacent paramagnetic Mn^II ions.     

Hydrothermal Synthesis,Crystal Structures,and Catalytic Properties of Three Coordination Polymers Containing ­Flexible Bis(benzimidazole) and Dicarboxylate Ligands

Three metal‐organic coordination polymers, namely {[Cd(L1)(1,2‐chdc)] · 2H₂O}_n ( 1 ), {[Ni(L2)(1,2‐chdc)] · H₂O}_n ( 2 ), and [Cd(L2)(npht)]_n ( 3 ) [L1 = 1,2‐bis(2‐methylbenzimidazol‐1‐ylmethyl)benzene, L2 = 1,2‐bis(5,6‐dimethylbenzimidazol‐1‐ylmethyl)benzene, 1,2‐H₂chdc = 1,2‐cyclohexanedicarboxylic acid, H₂npht = 3‐nitrophthalic acid] were synthesized under hydrothermal conditions and structurally characterized by single‐crystal X‐ray diffraction methods, IR spectroscopy, TGA, and elemental analysis. In compound 1 , two 1,2‐chdc^2– ligands connect two neighboring Cd atoms to form a dinuclear [Cd₂(1,2‐chdc)₂] subunit, which is further linked by L1 ligands to construct a 1D ladder‐like chain. Compound 2 exhibits a 2D (4,4) coordination network with {4⁴.6²} topology, whilst compound 3 shows a 1D helical chain structure. The fluorescence, UV/Vis diffuse reflection spectra, and catalytic properties of complexes 1 – 3 for the degradation of the congo red azo dye in a Fenton‐like process are investigated.