Stereospecific interactions between dinuclear complex cations involving square-planar [Pt(II)(μ-S)2(bpy)] (bpy = 2,2′-bipyridine) frameworks derived from optically active octahedral Co(III) units with d- or l-penicillaminates

The reaction of the octahedral mononuclear complex, trans(N)-[Co(l-pen-N,O,S)₂]⁻ (pen = penicillaminate), with [PtCl₂(bpy)] (bpy = 2,2′-bipyridine) stereoselectively gave an optically active S-bridged dinuclear complex, [Pt(bpy){Co(l-pen)₂}]Cl · 3H₂O (2Cl · 3H₂O), whose structure is enantiomeric to the previously reported [Pt(bpy){Co(d-pen)₂}]Cl · 3H₂O (1Cl · 3H₂O). The mixture of equimolar amounts of 1Cl · 3H₂O and 2Cl · 3H₂O in H₂O crystallizes as [Pt(bpy){Co(d-pen)₂}]_0.5[Pt(bpy){Co(l-pen)₂}]_0.5Cl · 7H₂O (3Cl · 7H₂O), in which the enantiomeric complex cations 1 and 2 are included in the ratio of 1:1. The crystal structures of 2Cl · 3H₂O and 3Cl · 7H₂O were determined by X-ray crystallography, and compared with that of 1Cl · 3H₂O. The structural feature for 2 is essentially consistent with that for 1, except for the absolute configurations around the octahedral Co(III) center. The optically active complex cation 2 exists as a monomer, accompanied by no intermolecular interactions in the π-electronic systems of bpy moieties. In the crystals of 3Cl · 7H₂O, on the other hand, the enantiomeric complex cations, [Pt(bpy){Co(d-pen)₂}]⁺ and [Pt(bpy){Co(l-pen)₂}]⁺, are arranged alternately while overlapping the bpy planes along a axis, and the π electronic system of the bpy framework in [Pt(bpy){Co(d-pen)₂}]⁺ interacts with those in [Pt(bpy){Co(l-pen)₂}]⁺. Differences between the crystal structures of 2Cl · 3H₂O and3Cl · 7H₂O significantly reflect their diffuse reflectance spectra. In aqueous solution, each cation in both 2Cl · 3H₂O and 3Cl · 7H₂O is comparatively put on a free environment without such intermolecular interactions.     

Zirconium and hafnium aqua complexes [(H2O)3M(P2W17O61)]: Synthesis, characterization and substitution of water by chiral ligand

The hydroxocomplexes [{(H₂O)M(μ₂-OH)(P₂W₁₇O₆₁)}₂]¹⁴⁻ (M = Zr, Hf) in HCl undergo cleavage of the hydroxo bridges with the formation of monomeric species [(H₂O)₃M(P₂W₁₇O₆₁)]⁶⁻. In the case of Hf single crystals of the composition (Me₂NH₂)_5.5(H)_1.5[(Hf(H₂O)₃)_0.9(WO)_0.1{P₂W₁₇O₆₁}]Cl·9.5H₂O (1), as the result of co-crystallization of [(H₂O)₃Hf(P₂W₁₇O₆₁)]⁶⁻ and [P₂W₁₈O₆₂]⁶⁻ salts, were isolated from these solutions and structurally characterized. Zr gives (Me₂NH₂)₂(H)₄[{(H₂O)₂ZrP₂W₁₇O₆₁}]·8.67H₂O (2), in whose structure chiral polymeric chains {[(H₂O)₂M(P₂W₁₇O₆₁)]}_n⁶ⁿ⁻ are present. Under hydrothermal conditions the water molecules in [(H₂O)₃M(P₂W₁₇O₆₁)]⁶⁻ are replaced by l-malic acid with the formation of stable chiral polyoxoanions, isolated as (NH₂Me₂)₈[M(L-ООССН(ОН)СН₂СОО)P₂W₁₇O₆₁]·7·9H₂O (M = Zr, 3; M = Hf, 4). The structures of 1, 2 and 3 were determined; 3 and 4 were found to be isostructural. The products were also characterized by elemental analysis, thermogravimetry and IR-spectroscopy.     

One-dimensional chain structures constructed from tetra(acetamidato)dirhodium(II,III) complexes and square planar platinum and palladium complexes

The reaction of [Rh₂(acam)₄(H₂O)₂]ClO₄ (1) (Hacam = acetamide) with K₂PtCl₄ in aqueous solution gave crystals of [Rh₂(acam)₄(H₂O)₂][Rh₂(acam)₄{(μ-Cl)₂PtCl₂}] · 2H₂O (2). The reaction of 1 with K₂PdCl₄ produced the palladium analog [Rh₂(acam)₄(H₂O)₂][Rh₂(acam)₄{(μ-Cl)₂PdCl₂}] · 2H₂O (3) and a small amount of an aquated palladium complex [Rh₂(acam)₄{(μ-Cl)₂PdCl(H₂O)}] · H₂O (4). Complexes 2 and 3 have anionic chains of [Rh₂(acam)₄{(μ-Cl)₂MCl₂}]⁻ (M = Pt, Pd), while 4 includes neutral chains of [Rh₂(acam)₄{(μ-Cl)₂PdCl(H₂O)}]. Although all of the structures include infinite chains of (-Rh-Rh-Cl-M-Cl-)_n (M = Pt, Pd), the chain structures are different; zigzag for 2 and 3 and helical for 4. In the structures of 2 and 3, the counter cation [Rh₂(acam)₄(H₂O)₂]⁺ made a hydrogen-bonded chain with the crystallization water molecules. The cationic chains and the anionic chains are connected with hydrogen bonds. In the structure of 4, the chains are also linked together by direct hydrogen bonds between the chains and those with the crystallization water molecules. ESR spectra of the powdered samples of 2 and 3 at 77 K were consistent with a rhombic structure: for 2, g₁ = 2.111, g₂ = 2.054, g₃ = 2.004; for 3, g₁ = 2.115, g₂ = 2.057, g₃ = 2.007. These results indicate that there is a spin flip-flop exchange between the cations, [Rh₂(acam)₄(H₂O)₂]⁺, and the units in the anionic chains. The electrical conductivities of 2 and 3 were in the order of 10⁻⁷ S cm⁻¹ at room temperature.     

Assembly of three novel 2D frameworks with helical chains based on [H2W12O40] clusters and lanthanide - Organic complexes

Three novel polyoxotungstate-based rare earth compounds, [(C₆H₅NO₂)Ln(H₂O)₅]₂[H₂W₁₂O₄₀] · nH₂O (Ln = Ce³⁺ (1), Pr³⁺(2), n = 7; Nd³⁺ (3), n = 6), have been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectra and TG analysis. The structural feature of compounds 1-3 is that the α-metatungstate cluster [H₂W₁₂O₄₀]⁶⁻ anions are linked by the lanthanide (Ln) cation-organic coordination complexes, resulting in a two-dimensional (2D) structure with helical chains. The magnetic properties of compounds 1 and 2 have been studied by measuring their magnetic susceptibility in the temperature range 2-300 K, indicating the existence of spin-orbital coupling interactions and antiferromagnetic response. Furthermore, the electrochemical properties of 1-3 were studied.     

Syntheses, structures, and magnetic properties of 3d-4f heterometallic complexes constructed from pyrazole-bridged CuLn dinuclear units

A series of pyrazole-bridged heterometallic 3d-4f complexes, [CuDy(ipdc)₂(H₂O)₄] · (2H₂O)(H₃O⁺) (1) and [CuLn(pdc)(ipdc)(H₂O)₄] · H₃O⁺ (Ln = Ho (2), Er (3), Yb (4); H₃ipdc = 4-iodo-3,5-pyrazoledicarboxylic acid; H₃pdc = 3,5-pyrazoledicarboxylic acid), {[Cu₃Ln₄(ipdc)₆(H₂O)₁₆] · xH₂O}_n (Ln = Sm (5), x = 8.5; Ln = Eu (6), x = 7; Ln = Gd (7), Tb (8), x = 9), have been synthesized and structurally characterized. Ligand H₃ipdc was in situ obtained by iodination of ligand H₃pdc. Complexes 1-4 are pyrazole-bridged heterometallic dinuclear complexes, and 2-4 are isostructural. Complexes 5-8 are isostructural and comprised of an unusual infinite one-dimensional tape-like chain based on pyrazole-bridged heterometallic dinuclear units. The magnetic properties of compounds 1-4, 7 and 8 have been investigated through the magnetic measurement over the temperature range of 1.8-300 K.     

Organic-inorganic hybrid materials: Ligand influences on the structural chemistry of copper-vanadates

Hydrothermal reactions were used in the preparation of a series of bimetallic organic-inorganic hybrid materials of the M(II)/V_xO_y/organonitrogen ligand class. Compound 1, [{Cu₂(bpa)₂(C₂O₄)}₂V₄O₁₂]·H₂O, is molecular, while [{Cu(terpy)}₂V₆O₁₇] (2), [Cu₂(bpyrm)V₄O₁₂] (4) and [{Cu(phen)(H₂O)₂}VOF₄(H₂O)]·2H₂O (5) are two-dimensional, three-dimensional and one-dimensional, respectively (bpa = 2,2′-bipyridylamine; terpy = 2,2′:6,2″-terpyridine; bpyrm = 2,2′-bipyrimidine; phen = 1,10-phenanthroline). In contrast to the 2-D structure of 2, the Ni(II) analogue [{Ni(terpy)}₂V₄O₁₂]·2H₂O (3) is one-dimensional. The {V₄O₁₂}⁴⁻ cluster is a building block of structures 1, 3, and 4 while 2 is constructed from {V₆O₁₇}⁴⁻ rings.     

Selective synthesis of triangular cluster oxido-sulfidocomplexes of Mo and W: High yield preparations of [Mo3O2S2(H2O)9], [W3O2S2(H2O)9], [W2MoO2S2(H2O)9] and their derivatization

Reaction of [Mo₂O₂(μ-S)₂(H₂O)₆]²⁺ with Mo(CO)₆ or metallic Mo under hydrothermal conditions (140 °C, 4 M HCl) gives oxido-sulfido cluster aqua complex [Mo₃(μ₃-S)(μ-O)₂(μ-S)(H₂O)₉]⁴⁺ (1). Similarly, [W₃(μ₃-S)(μ-O)₂(μ-S)(H₂O)₉]⁴⁺ (2) is obtained from [W₂O₂(μ-S)₂(H₂O)₆]²⁺ and W(CO)₆. While reaction of [Mo₂O₂(μ-S)₂(H₂O)₆]²⁺ with W(CO)₆ mainly proceeds as simple reduction to give 1, [W₂O₂(μ-S)₂(H₂O)₆]²⁺ with Mo(CO)₆ produces new mixed-metal cluster [W₂Mo(μ₃-S)(μ-O)₂(μ-S)(H₂O)₉]⁴⁺ (3) as main product. From solutions of 1 in HCl supramolecular adduct with cucurbit[6]uril (CB[6]) {[Mo₃O₂S₂(H₂O)₆Cl₃]₂CB[6]}Cl₂⋅18H₂O (4) was isolated and structurally characterized. The aqua complexes were converted into acetylacetonates [M₃O₂S₂(acac)₃(py)₃]PF₆ (M₃ = Mo₃, W₃, W₂Mo; 5a-c), which were characterized by X-ray single crystal analysis, electrospray ionization mass spectrometry and ¹H NMR spectroscopy. Crystal structure of (H₅O₂)(Me₄N)₄[W₃(μ₃-S)(μ₂-S)(μ₂-O)₂(NCS)₉] (6), obtained from 2, is also reported.     

Synthesis and characterization of 8-quinolinolato vanadium(IV) complexes

Reaction of vanadium(III) chloride with 8-quinolinol (Hqn) gave a mononuclear vanadium(IV) complex, [VOCl₂(H₂O)₂] 1) · 2H₂qn · 2Cl · CH₃CN, and three dinuclear vanadium(IV) complexes: [V₂O₂Cl₂(qn)₂(H₂O)₂] (2) · Hqn, [V₂O₂Cl₂(qn)₂(C₃H₇OH)₂] (3), and [V₂O₂Cl₂(qn)₂(C₄H₉OH)₂] (4). Reaction of vanadium(III) chloride with 5-chloro-8-quinolinol (HClqn) gave four dinuclear vanadium(IV) complexes: [V₂O₂Cl₂(Clqn)₂(H₂O)₂] (5) · 2HClqn, [V₂O₂Cl₂(Clqn)₂(C₃H₇OH)₂] (6), [V₂O₂Cl₂(Clqn)₂(C₆H₅CH₂OH)₂] (7), and [V₂O₂Cl₂(Clqn)₂(C₄H₉OH)₂] (8) · 2C₄H₉OH. Reaction of vanadium(III) chloride with 5-fluoro-8-quinolinol (HFqn) gave two dinuclear vanadium(IV) complexes: [V₂O₂Cl₂(Fqn)₂(H₂O)₂] (9) · HFqn · 2H₂O and V₂O₂Cl₂(Fqn)₂(C₃H₇OH)₂] (10). X-ray structures of 1 · 2H₂qn · 2Cl · CH₃CN, 3, 4, 6, 7, 8 · 2 t-BuOH, and 10 have been determined. As to the mononuclear species 1 · 2H₂qn · 2Cl · CH₃CN, coordination of Hqn to vanadium does not occur, but protonation to Hqn occurs to give H₂qn⁺, which links 1’s through hydrogen bonding, while each of the dinuclear species has a terminal and a bridging qn (or Clqn, Fqn) ligand, giving rise to a (V-O)₂ ring. Magnetic measurements of 3, 4, 6, 7, and 10 in solid form show very weak antiferromagnetic behavior, and the effective magnetic moments are close to spin only value (2.44) of d¹-d¹ system, while ESR of 3 in THF shows dissociation to monomeric species. Change from mononuclear, 1, to dinuclear, 2, species was followed by the change of electronic spectrum.     

Structures and properties of octaethylporphinato(phenolate)iron(III) complexes with NH?O hydrogen bonds: modulation of Fe-O bond character by the hydrogen bond

Iron(III) porphinate complexes of phenolate that have NH?O hydrogen bonds on the coordinating oxygen, [Fe^III(OEP){O-2,6-(RCONH)₂C₆H₃}] (R = CF₃ (1), CH₃ (3)) and [Fe^III(OEP)(O-2-RCONHC₆H₄)] (R = CF₃ (2), CH₃ (4)) (OEP = 2,3,7,8,12,13,17,18-octaethyl-21H, 23H-porphinato), were synthesized and characterized as models of heme catalase. The presence of NH?O hydrogen bonds was established by their crystal structures and IR shifts of the amide NH band. The crystal structure of 1 shows an extremely elongated Fe-O bond, 1.926(3) Å, compared to 1.887(2) Å in 2 or 1.848(4) Å in [Fe^III(OEP)(OPh)]. The NH?O hydrogen bond decreases an electron donation from oxygen to iron, resulting in a long Fe-O bond and a positive redox potential.     

Polymorphism in intercluster salt system: two crystal structures of [Al13O4(OH)24(H2O)12][H2W12O40](OH) · nH2O

In this paper, we report the syntheses and crystal structures of two intercluster salt compounds, [Al₁₃O₄(OH)₂₄(H₂O)₁₂][H₂W₁₂O₄₀](OH) · 20H₂O (1) and [Al₁₃O₄(OH)₂₄(H₂O)₁₂][H₂W₁₂O₄₀](OH) · 24H₂O (2). The crystal structures of these compounds show that they are polymorphs to each other with different modes of packing of the and ions. The structures of 1 and 2 can be described as alternating arrangements of ionic clusters that optimize electrostatic interactions and hydrogen bonds between them. The structure of 1 is analogous to the PtS structure and that of 2 is similar to the β-BeO structure with the clusters forming tetrahedral or square planar coordination geometries to each other.     

Supramolecular architectures built of triangular molybdenum(IV) heterometallic clusters encapsulating novel water clusters

The hydrothermal reaction of the dimolybdenum(V) Na₂[Mo₂O₃S(HNTA)₂] · 6H₂O (1) and the lanthanide(III) ion yield the neutral trimolybdenum(IV) heterometalic cluster, [(H₂O)₈NdMo₃O₃S(HNTA)₂(NTA)] · 7H₂O (2) (NTA = nitrilotriacetato ligand). The addition reaction of Ag⁺ and [Mo₃O₄(C₂O₄)₃(H₂O)₃]²⁻ affords the anionic heterometallic cluster in N(C₂H₅)₄[Ag(H₂O)₃Mo₃O₄(C₂O₄)₃(H₂O)₃] · 5H₂O (3). The H-bonded self-assemblies of the resulting asymmetric and larger heterometallic clusters form the 2D layered structure and 3D supramolecular open framework in 2 and 3, respectively, with larger pores to be stabilized by water clusters. These water clusters appear as (H₂O)₄ and (H₂O)₁₈ in 2 and (H₂O)₂₂ in 3.     

Protonated N-heterocycle-templated supramolecular frameworks built of triangular molybdenum(IV) clusters

A series of porous supramolecular complexes (Hoxine)₂ · [Mo₃O₄(C₂O₄)₃(H₂O)₃] · 5H₂O (1),(Hphen)₂ · [Mo₃O₄(C₂O₄)₃(H₂)₃]  · 0.5C₂H₅OH · 7H₂O (2), H₂bpy · [Mo₃O₄(C₂O₄)₃(H₂O)₃] · 2.5H₂O (3), H₂TTD · [Mo₃O₄(C₂O₄)₃(H₂O)₃] · C₂H₅OH · 3H₂O (4), (oxine = 8-hydroxyquinoline, phen = 1,10-phenanthroline, bpy = 4,4′-bipyridine, TTD = triethylene diamine) have been prepared and characterized by single-crystal X-ray crystallography, elemental analysis and infrared spectroscopy. Self-assembly of [Mo₃O₄(C₂O₄)₃(H₂O)₃]²⁻ directed by H-bonding association between the coordination water molecules and oxalate groups forms 2-D host H-bonded single layer in 1, double layer in 2 and 3, and undulated layer in 4 depending on the nature of the guest protonated N-heterocycles. Unlike cis-Hoxine⁺ or Hphen⁺ that employs lattice water molecules H-bonded to them to interconnect the host layers, trans-H₂bpy²⁺ or H₂TTD²⁺ acts a linker between the neighboring host layers to form 3-D supramolecular frameworks with channeled structures wherein the guest protonated cations are located.     

Iron(III), chromium(III) and cobalt(II) complexes with squarate: Synthesis, crystal structure and magnetic properties

The preparation and variable temperature-magnetic investigation of three squarate-containing complexes of formula [Fe₂(OH)₂(C₄O₄)₂(H₂O)₄]·2H₂O (1) [Cr₂(OH)₂(C₄O₄)₂(H₂O)₄]·2H₂O (2) and [Co(C₄O₄)(H₂O)₄]_n (3) [H₂C₄O₄ = 3.4-dihydroxycyclobutene-1,2-dione (squaric acid)] together with the crystal structures of 1 and 3 are reported. Complex 1 contains discrete centrosymmetric [Fe₂(OH)₂(C₄O₄)₂(H₂O)₄] diiron(II) units where the iron pairs are joined by a di-μ-hydroxo bridge and two squarate ligands acting as bridging groups through adjacent oxygen atoms. Two coordinated water molecules in cis position complete the octahedral environment at each iron atom in 1. The iron-iron distance with the dinuclear unit is 3.0722(6) Å and the angle at the hydroxo bridge is 99.99(7)°, values which compare well with the corresponding ones in the isostructural compound 2 (2.998 Å and 99.47°) whose structure was reported previously. The crystal structure of 3 contains neutral chains of squarato-O¹,O³-bridged cobalt(II) ions where four coordinated water molecules complete the six-coordination at each cobalt atom. The cobalt-cobalt separation across the squarate bridge is 8.0595(4) Å. A relatively important intramolecular antiferromagnetic coupling occurs in 1 whereas it is very weak in 2, the exchange pathway being the same [J = −14.4 (1) and −0.07 cm⁻¹ (2), the spin Hamiltonian being defined as ]. A weak intrachain antiferromagnetic interaction between the high-spin cobalt(II) ions occurs in 3 (J = −0.30 cm⁻¹). The magnitude and nature of these magnetic interactions are discussed in the light of their respective structures and they are compared with those reported for related systems.     

Novel topological nets of lanthanide metal-organic frameworks based on dicarboxylate ligands

Four novel topological nets of lanthanide metal-organic frameworks: [Sm₂(op)₃(H₂O)]_n (1), {Ln₂(op)₂(ox)(H₂O)₄] · H₂O}_n (Ln = La, 2; Sm, 3), {[La₂(mp)₂(ox)(H₂O)₄] · 2H₂O}_n (4), [La₂(op)₂(mp)(H₂O)₄]_n (5) (op = o-phthalate, mp = m-phthalate, and ox = oxalate), have been hydrothermally synthesized and characterized. Compound 1 exhibits novel (3,4,5,6)-connected five-nodal two-dimensional net, compound 2 and 3 show the (3,4)-connected V₂O₅ topologies, compound 4 has the (4,5)-connected topological net, and compound 5 shows the (4,5)-connected four-nodal three-dimensional network. Photoluminescent analyses of 1 and 3 show strong blue emission in the solid state at room temperature.     

Construction of a series of 0D, 2D and 3D inorganic-organic hybrid coordination polymers based on octamolybdate and 2-(2-pyridyl)imidazole and its derivative

Four octamolybdate-based compounds, that is, Cu^II₂(L¹)₄(Mo₈O₂₆) (1), Cu^II₂(HL²)₄(Mo₈O₂₆)₂ (2), [Cu^IIL²(H₂O)(Mo₈O₂₆)_0.5]·2H₂O (3) and [Cu^IIL²(H₂O)(Mo₈O₂₆)_0.5]·2H₂O (4) (L¹ = 2-(2-pyridyl)imidazole, L² = 2-(1-(pyridine-3-ylmethyl)-1H-imidazol-2-yl)pyridine), have been hydrothermally synthesized via changing the reaction conditions and structurally characterized by single-crystal X-ray diffraction. With L¹ ligand, we obtained compound 1, which is a 0D molecule and extends to a 3D supramolecular structure via hydrogen-bonding interactions. By using L² instead of L¹ ligand, compound 2 comes into being which is as well a discrete molecule and further extended to a 3D supramolecular structure by hydrogen bonds. Intriguingly, compounds 3 and 4 are supramolecular isomers: the former is a 2D 4-connected network and the latter is a 3D (3,4)-connected framework. The measurements of diffuse reflectance for compounds 1-4 indicate that they are potential wide gap semiconductors.     

Diverse coordination of polynuclear copper(II) complexes constructed from benzene tetracarboxylates

The reaction of aqueous solutions of the preformed 1:1 Cu(ClO₄)₂-polydentate amine with tetrasodium 1,2,4,5-benzene tetracarboxylate (Na₄bta) afforded three different types of polynuclear compounds. These include the tetranuclear complexes: [Cu₄(Medpt)₄(μ₄-bta)(ClO₄)₂(H₂O)₂](ClO₄)₂·2H₂O (1), [Cu₄(pmdien)₄(μ₄-bta)(H₂O)₄](ClO₄)₄ (2), [Cu₄(Mepea)₄(μ₄-bta)(H₂O)₂](ClO₄)₄(3), [Cu₄(TPA)₄(μ₄-bta)](ClO₄)₄·10H₂O (4) and [Cu₄(tepa)₄(μ₄-bta)](ClO₄)₄·2H₂O (5), the di-nuclear: [Cu₂(DPA)₂(μ₂-bta)(H₂O)₂]·4H₂O (6), [Cu₂(dppa)₂(μ₂-bta)(H₂O)₂]·4H₂O (7) and [Cu₂(pmea)₂(μ₂-bta)]·14H₂O (8) and the trinuclear complex [Cu₃(dppa)₃(μ₃-bta)(H₂O)_2.25](ClO₄)₂·6.5H₂O (9) where Medpt = 3,3′-diamino-N-methyldipropylamine, pmedien = N,N,N′,N″,N″-pentamethyldiethylenetriamine, Mepea = [2-(2-pyridyl)ethyl]-(2-pyridylmethyl)methylamine, TPA = tris(2-pyridylmethyl)amine, tepa = tris[2-(2-pyridyl)ethyl)]amine, DPA = di(2-pyridymethyl)amine, dppa = N-propanamide-bis(2-pyridylmethyl)amine and pmea = bis(2-pyridylmethyl)-[2-(2-pyridylethyl)]amine. The complexes were structurally characterized by elemental analyses, spectroscopic techniques, and by X-ray crystallography for complexes 1, 2, 4, 6, 7 and 9. X-ray structure of the complexes reveal that bta⁴⁻ is acting as a bridging ligand via its four deprotonated caboxylate groups in 1, 2 and 4, three carboxylate groups in 9 and via two trans-carboxylates in 6 and 7. The complexes exhibit extended supramolecular networks with different dimensionality: 1-D in 2 and 4 due to hydrogen bonds of the type O-H···O, 2-D in 1 and 7, and 3-D network in 6 as a result of hydrogen bonds of the types N-H···O and O-H···O. Magnetic susceptibility measurements showed very weak antiferromagnetic coupling between the Cu^II ions in 1-5, 7-9 (|J| = 0.02-0.87 cm⁻¹) and weak ferromagnetic coupling for 6 (J = 0.08 cm⁻¹).     

Hydrogen-bonded copper(II) and nickel(II) complexes and coordination polymeric structures containing reduced Schiff base ligands

Complexes [Cu(HSas)(H₂O)] · 2H₂O (H₃Sas = N-(2-hydroxybenzyl)-l-aspartic acid) (1), [Cu(HMeSglu)(H₂O)] · 2H₂O (H₃MeSglu = (N-(2-hydroxy-5-methylbenzyl)-l-glutamic acid) (2), [Cu₂(Smet)₂] (H₂Smet = (N-(2-hydroxybenzyl)-l-methionine) (3), [Ni(HSas)(H₂O)] (4), [Ni₂(Smet)₂(H₂O)₂] (5), and [Ni(HSapg)₂] (H₂Sapg = (N-(2-hydroxybenzyl)-l-aspargine) (6) have been synthesized and characterized by chemical and spectroscopic methods. Structural determination by single crystal X-ray diffraction studies revealed 1D coordination polymeric structures in 2 and 4, and hydrogen-bonded network structure in 5 and 6. In contrast to previously reported coordination compounds with similar ligands, the phenol remains protonated and bonded to the metal ions in 2 and 4, and also probably in 1. However, the phenolic group is non-bonded in 6.     

Three new multidimensional organic-inorganic hybrids based on polyoxometalates and copper coordination polymers with 4,4′-bipyridine ligands

Three new organic-inorganic hybrid materials with 4,4′-bipy ligands and copper cations as linkers, [Cu^II(H₂O)(4,4′-bipy)₂][Cu^II(H₂O)(4,4′-bpy)₂]₂H[Cu^IIP₈Mo₁₂O₆₂H₁₂] · 5H₂O (1), [Cu^I(4,4′-bipy)][Cu^II(4,4′-bipy)]₂ (BW₁₂O₄₀) · (4,4′-bipy) · 2H₂O (2) and [Cu^I (4,4′-bipy)]₃ (PMo₁₂O₄₀) · (pip) · 2H₂O (3) (pip = piperazine; 4,4′-bipy = 4,4′-bipyridine), have been hydrothermally synthesized. The single X-ray structural analysis reveals that the structure of 1 is constructed from [Cu(H₂O)(4,4′-bipy)₂] complexes into a novel, three-dimensional supermolecular network with 1-D channels in which Cu[P₄Mo₆]₂ dimer clusters reside. To the best of our knowledge, compound 1 is the first complex in which the [P₄Mo₆] clusters have been used as a non-coordinating anionic template for the construction of a novel, three-dimensional supermolecular network. Compound 2 is constructed from the six-supported [BW₁₂O₄₀]⁵⁻ polyoxoanions and [Cu^I(4,4′-bipy)] and [Cu^II(4,4′-bipy)] groups into a novel, 3-D network. Compound 3 exhibits unusual 3-D supramolecular frameworks, which are constructed from tetrasupporting [PMo₁₂O₄₀]³⁻ clusters and [Cu^I (4,4′-bipy)_n] coordination polymer chains. The electrochemical properties of 2 and 3 have been investigated in detail.     

Syntheses, crystal structures and magnetic properties of trinuclear and [3 × 1 + 1 × 2] pentanuclear complexes derived from a compartmental ligand: Role of solvent on nuclearity and number of components

Reaction of [Cu^IIL⊂(H₂O)] (H₂L = N,N′-ethylenebis(3-ethoxysalicylaldimine)) with nickel(II) perchlorate in 1:1 ratio in acetone produces the trinuclear compound [(Cu^IIL)₂Ni^II(H₂O)₂](ClO₄)₂ (1). On the other hand, on changing the solvent from acetone to methanol, reaction of the same reactants in same ratio produces the pentametallic compound [(Cu^IIL)₂Ni^II(H₂O)₂](ClO₄)₂·2[Cu^IIL⊂(H₂O)]·2MeOH (2A), which loses solvated methanol molecules immediately after its isolation to form [(Cu^IIL)₂Ni^II(H₂O)₂](ClO₄)₂·2[Cu^IIL⊂(H₂O)] (2B). Clearly, formation of 1 versus 2A and 2B is solvent dependent. Crystal structures of 1 and 2A have been determined. Interestingly, compound 2A is a [3 × 1 + 1 × 2] cocrystal. The cryomagnetic profiles of 1 and 2B indicate that the two pairs of copper(II)···nickel(II) ions in the trinuclear cores in both the complexes are coupled by almost identical moderate antiferromagnetic interaction (J = −22.8 cm⁻¹ for 1 and −26.0 cm⁻¹ for 2B).     

Synthesis, crystal structures, and fluorescence properties of six complexes with thiophene derivative carboxylic acid ligand

The crystallization of 2,3-dihydro-thieno[3,4-b][1,4] dioxine-5,7-dicarboxylic acid (H₂tddc) with divalent transitional metal (Co, Ni, Zn, Cd) or with tervalent lanthanide metal (Sm) and with mixed ligand 4,4′-bipyridine (4,4′-bipy) or 1,10-phenanthroline (1,10-phen) formed six new complexes: [Co(C₈H₄O₆S) · 3H₂O] (1), [Co(C₈H₄O₆)(1,10-phen)(H₂O)] · H₂O (2), [Ni(C₈H₄O₆S)(4,4′-bipy)(H₂O)] · 3H₂O (3) [Sm(C₈H₄O₆S)(NO₃)(H₂O)₄] · 2H₂O (4), [Zn(C₈H₄O₆S)(H₂O)₃] (5), and [Cd₂(C₈H₄O₆S)₂(4,4′-bipy)₂] (6). The structures of these six crystals have been characterized by single-crystal X-ray diffraction analyses, which revealed that complexes 1, 4, 5 are all one-dimensional chain structures and they self-assemble into three-dimensional super-molecules via the hydrogen bond interactions and π-π stacking interactions, 2 is also a one-dimensional chain structure but still self-assembles into one-dimensional double-chains, the complex 3 has two-dimensional undulating parallelogram grid structure extended along the bc-plane, the crystal of 6 is a 3D threefold interpenetration topology framework with 4⁶6³8 nodes. The photoluminescent properties of the H₂tddc ligand and the six compounds have been measured in the solid state at room temperature. Free ligand has no luminescence, while its complexes 1, 4, and 6 all exhibit intense photoluminescence which implies that these complexes may be excellent candidates for potential photoactive materials.