Ferromagnetic coupling in a novel dicyanamide-bridged dinuclear gadolinium(III) complex [Gd2(dca)4(OH)2 (NITpPy)4] (NITpPy = 4-pyridyl-nitronyl nitroxide radical)

The novel six-coordinated gadolinium(III) complex of formula [Gd₂(dca)₄(OH)₂(NITpPy)₄] (1) (dca = dicyanamide, NITpPy = 4-pyridyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-oxy-3-oxide) has been prepared and characterized by X-ray crystallography. Compound 1 is a dimer structure made up of double μ_1,5-dca-bridged gadolinium(III) ions and one terminal dca ligand; variable-temperature magnetic susceptibility measurements reveal the occurrence of a significant ferromagnetic interaction directly spin polarization through the NITpPy–Gd(III)–NITpPy pathway with J = 11.56 cm⁻¹.     

3D Ln–Ag (Ln = Nd; Eu) coordination polymers based on isonicotinate and oxalate ligands: Synthesis, crystal structures and luminescence

The self-assembly of isonicotinic acid with metal salts under hydrothermal conditions obtained two new 4d–4f coordination polymers, LnAg(OX)(IN)₂·H₂O (Ln = Nd (1); Eu (2), OX = oxalic acid, IN = isonicotinic acid). The 3D isostructural complexes 1 and 2 are constructed by the assembly of 2D layers, which are built by carboxylate groups of isonicotinic acid and oxalate ligands coordinating to metal centers, with 1D linear linkers completed by silver ions. Furthermore, the luminescent property of complex 2 was investigated.     

A new binuclear potassium (І) complex with a novel 1D infinite water chain containing (H2O)12 clusters

A novel 1D infinite water chain made of (H₂O)₁₂ clusters containing two different chair water hexamers is found in the binuclear coordination compound, [K₂(L)₂(phen)₄]·6H₂O (1) (where L = 2,2′-azanediyldibenzoic dianion, phen = 1,10′-phenanthroline), which has been synthesized and structurally characterized by single-crystal X-ray diffraction. The fluorescence spectrum and thermogravimetric analysis (TGA) of the title complex 1 have been also discussed.     

1,3,5-Triaza-7-phosphaadamantane (PTA) ligated iridium(I) complexes as catalysts for the intramolecular hydroamination of 4-pentyn-1-amine in water

The water-soluble complex [Ir(COD)(PTA)₃]Cl (1, PTA = 1,3,5-triaza-7-phosphaadamantane) was prepared by the reaction of [IrCl(COD)]₂ with six equivalents of PTA under a nitrogen atmosphere. Compound 1 was fully characterized in solution and the solid state. 1 crystallized in the monoclinic space group C2/c with a = 29.648(9) Å, b = 11.238(2) Å, c = 19.930(2) Å, and β = 96.55(2)°. Complex 1 and the related Ir(I) compounds, [IrCl(CO)(PTA)₃] (2) and [Ir(CO)(PTA)₄]Cl (3), were active catalysts in the intramolecular hydroamination of 4-pentyn-1-amine in water. This is the first reported study of the Ir(I) mediated transformation in aqueous media.     

Synthesis of a fluorescent gold(I) complex with a thiosemicarbazone, [Au2(3-NO2-Hbtsc)4]Cl2 · 2CH3CN

Direct reaction of gold(I) chloride with 3-nitrobenzaldehyde thiosemicarbazone (3-NO₂-Hbtsc) in the presence of triphenylphosphine in acetonitrile has yielded ionic complex, [Au₂(3-NO₂-Hbtsc)₄]Cl₂ · 2CH₃CN (1). It exhibited an intense fluorescence band (λ_em) at 383 nm (λ_ex = 300 nm), and two bands of medium intensity at 413 and 436 nm (λ_ex = 350 nm). Complex 1 represents first example of ionic gold(I) complex with a thiosemicarbazone.     

1-D and 2-D lanthanide coordination polymers constructed from 4-sulfobenzoate and 1,10-phenanthroline

Two complexes {[Dy₂(4-SBA)₃(phen)₂(H₂O)₄] · 2H₂O}_n (1) and {[Eu₂(4-SBA)₃(phen)₂(H₂O)₂]}_n (2) (4-SBA = 4-sulfobenzoate, phen = 1,10-phenanthroline) were synthesized and their structures were determined by X-ray crystallography. The 1 has a 1-D chain structure by bidentate and tridentate 4-SBA ligands as linkages and 3-D network was formed by strong hydrogen bonds. The 2 has a 2-D network structure by tridentate and tetradentate 4-SBA ligands as linkages. The luminescence properties and thermal stability of the two complexes were investigated.     

One-dimensional manganese(II) complex with only end-to-end azide ligands: Crystal structure and magnetic characterization

A novel one-dimensional azido-bridged manganese(II) complex of formula [Mn(L)₂(N₃)](ClO₄) 1 has been synthesized and characterized crystallographically and magnetically, where L is the bidentate Schiff base obtained from the condensation of pyridine-2-carbaldehyde with 4-methoxyl aniline. Complex 1 is of one-dimensional chain structure with single end-to-end azido bridges. Magnetic analysis reveals that the weak antiferromagnetic interaction is mediated by the single end-to-end azido bridge with the exchange parameter J = −6.60 cm⁻¹.     

First dicadmium(II) complex of tripodal amide ligand with one edge-sharing monocapped octahedral geometry

A new dicadmium(II) complex [Cd₂(L)₂(H₂O)₂](NO₃)₄ · 8H₂O (1) with the tripodal amide ligand L (tris[3-aza-2-oxo-4-(2-pyridyl)butyl]amine) was synthesized and structurally characterized. Complex 1 is revealed as a dinuclear 2:2 (Cd:L) complex, in which each cadmium(II) ion is hepta-coordinated with the coordination surrounding of distorted monocapped octahedral geometry. Two cadmium(II) ions are dibridged by two carbonyl μ-O atoms forming a Cd₂(μ-O)₂ parallelogram-type moiety. Interestingly, the dinuclear coordination sphere can be seen as resulting from the fusion of two distorted monocapped octahedral [Cd(L)(H₂O)]²⁺ units through sharing one edge originated from the two carbonyl μ-O atoms as a first example. Comparative NMR, IR and FAB-mass data of 1 are also discussed.     

Solvothermal synthesis of 1D and 2D cobalt(II) and nickel(II) coordination polymers with 2,5-dihydroxy-p-benzenediacetic acid

1D cobalt(II) and nickel(II) coordination polymers {[Co(dba)(H₂O)₄] · H₂O}_n (1) and {[Ni(dba)(H₂O)₄] · H₂O}_n (2) (H₂dba = 2,5-dihydroxy-p-benzenediacetic acid) were synthesized under low temperature solvothermal condition. When 4,4′-bipyridine (bpy) was introduced to the synthetic systems of 1 and 2, respectively, two novel 2D coordination polymers {[Co(dba)(bpy)] · 0.5H₂O}_n (3) and [Ni(dba)(bpy)(H₂O)₂]_n (4) with different structures were obtained. All of the compounds were characterized by elemental analysis, FT-IR, UV–Vis spectra and single crystal X-ray diffraction.     

An unexpected sulfinate–sulfonate mixed coordination polymer of copper(II)

By reaction of copper nitrate trihydrate and 2,2′-dipyridyldisulfide in both aerobic and anaerobic conditions, the mixed [{Cu(2-pySO₂)₂}_n]–[{Cu(2-pySO₃)₂}_n] coordination polymer of copper(II) (1) has been synthesized. The X-ray diffraction analysis indicates that complex 1 exhibits an infinite one-dimensional polymeric chain consisting of [Cu(C₅H₄N)₂] building units connected by SO₂/SO₃ groups. The atom which has been labelled O3 is only present in 60% of the molecules. Complex 1 exhibits a very weak ferrogmagnetic spin coupling (zJ = +0.40 cm⁻¹).     

Synthesis, crystal structures and photoluminescence of Zn–Ln heterometallic polymers based on pyridine-2,3-dicarboxylic acid

Three new two-dimensional 3d–4f isostructural heterometallic coordination polymers, namely [Ln₂Zn(2,3-pydc)₄(H₂O)₄·4H₂O]_n (Ln = Sm (1), Eu (2), Gd (3), 2,3-pydcH₂ = pyridine-2,3-dicarboxylic acid) have been successfully synthesized by the hydrothermal reactions of Ln₂O₃, Zn(NO₃)₂·6H₂O, H₂pydc and H₂O. X-ray diffraction analyses reveal that they possess a 2D heterometallic framework containing 1D lanthanide chains based on dimeric [Ln(2,3-pydc)₂(H₂O)₂]₂ unit. The Zn(II) ion, which is six-coordinated by four oxygen and two nitrogen atoms from four 2,3-pydc²⁻ ligands, as a bridge, links the lanthanide chains to make the 1D chains further extend into 2D layer framework. Furthermore, the neighboring layers are assembled into three-dimensional supramolecular network through inter-layer O–HO and C–HO hydrogen-bond interactions. In addition, the solid-state luminescent property of complex 2 was investigated.     

pH Dependent formations of dinuclear molybdenum(V) and incomplete cubane molybdenum(IV) complexes with nitrilotriacetate

Nitrilotriacetato oxomolybdenum(V) dinuclear complex (NH₄)₄[cis-Mo₂O₄(nta)₂] · 7H₂O (1) (H₃nta = nitrilotriacetic acid) and its incomplete cubane-type trinuclear molybdenum(IV) complex [Mo₃O(OH)₃(Hnta)₃] · Cl · 3H₂O (2) are isolated in a weak acidic and an acidic solutions, respectively (pH 4.5 and 1.0). The nitrilotriacetate ligand in the anion 1 or the cation 2 displays tridentate mode through the nitrogen atom and the oxygen atoms of β-carboxy groups. Unusual protonations of bridged oxygen atoms in 2 have not effect on the skeleton of molybdenum(IV) cap Mo₃O unit. There are obvious dissociations of molybdenum(V) complexes based on ¹³C NMR observations in solution.     

A hemidirected 1-D coordination polymer [Pb2(H2O)2(HBTC)2] · 3H2O extended in holodirected 3-D by weak Pb–O interactions

A new complex, [Pb₂(H₂O)₂(HBTC)₂] · 3H₂O (H₃BTC = 1,3,5-Benzenetricarboxylic acid) (1), has been synthesized under hydrothermal condition. The single-crystal analysis shows that 1 consists of 1-D double-chains with Pb(II) six-coordinated by three H₃BTC and one H₂O molecule with the Pb–O bond distances in the range of 2.56–2.76 Å. When the Pb–O bonding limit extends from 2.76 to 2.90 Å, the potential weak bonds of Pb–O can be found and the coordination number of Pb will increase from six to nine. As a result, the coordination geometry of Pb(II) transforms from hemidirected to holodirected and an infinite 3-D framework is obtained by the connection of the double-chains. The IR spectrum and the TGA–DTA curve of 1 are also reported in this paper.     

Synthesis and structural characterization of two novel 2D coordination polymers [PbCl(atza)]n and [PbCl(a4-ptz)]n

Reactions of Katza (atza⁻ = 5-aminotetrazole-1-acetato) or Ka4-ptz (a4-ptz⁻ = 5-[N-acetato(4-pyridyl)]tetrazole) with PbCl₂in aqueous solution, produced two new Pb(II) compounds, [PbCl(atza)]_n (1) and [PbCl(a4-ptz)]_n (2). Both compounds were structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. In 1 or 2, the Pb(II) centers are connected through the atza⁻ or a4-ptz⁻ bridging ligand to form a two-dimensional layered structure. The luminescence properties of 1 and 2 were investigated at room temperature in the solid state.     

Formation of an unusual copper(II) complex from the degradation of a novel tricopper(II) carbohydrazone complex

An unusual copper(II) complex [Cu(L^1a)₂Cl₂] CH₃OH·H₂O·H₃O⁺Cl⁻ (1a) was isolated from a solution of a novel tricopper(II) complex [Cu₃(HL¹)Cl₂]Cl₃·2H₂O (1) in methanol, where L^1a is 3-(2-pyridyl)triazolo[1,5-a]-pyridine, and characterized with single crystal X-ray diffraction study. The tricopper(II) complex of potential ligand 1,5-bis(di-2-pyridyl ketone) carbohydrazone (H₂L¹) was synthesized and physico-chemically characterized, while the formation of the complex 1a was followed by time-dependant monitoring of the UV–visible spectra, which reveals degradation of ligand backbone as intensity loss of bands corresponding to O → Cu(II) charge transfer.     

Catalytic properties of Ru-η-C6H6-diphosphine complexes for hydrogenation of benzene in aqueous-organic biphasic system

The influences of pH on the catalytic properties of Ru-η⁶-C₆H₆-diphosphine complex [RuCl(η⁶-C₆H₆)(BISBI)]Cl (1) (BISBI = 2,2′-bis(diphenylphosphinomethyl)-1,1′-biphenyl), [RuCl(η⁶-C₆H₆)(BDPX)]Cl (2) (BDPX = 1,2-bis(diphenylphosphinomethyl)benzene), Ru₂Cl₄(η⁶-C₆H₆)₂(μ₂-BDNA) (3) (BDNA = 1,8-bis(diphenylphosphinomethyl)naphthalene), [RuCl(η⁶-C₆H₆)(BISBI)]BF₄ (4), [RuCl(η⁶-C₆H₆)(BDPX)]BF₄ (5), and [(η⁶-C₆H₆)₂Ru₂Cl₂(μ₂-Cl)(μ₂-BDNA)]BF₄ (6) for the hydrogenation of benzene were investigated in aqueous-organic biphasic system. The hydrogenation of benzene catalyzed by all complexes yielded only cyclohexane. The catalytic results revealed that the stabilities of these complexes were not only closely relative with their compositions or molecular structures but also the pH value of aqueous solution. Complexes 1 and 2 were homogeneous catalysts at pH <5, but complexes 3, 4, 5 and 6 were partly decomposed in the same reaction conditions and played simultaneously the roles of homogeneous and heterogeneous catalysts. When the pH was up to 12, all of six complexes were gradually decomposed to Ru(0) particles. The addition of extra phosphine ligand was favorable to prevent these complexes from decomposing in the catalytic process. The experiment of mercury poisoning and the curve of conversion vs time strongly supported above conclusions.     

Synthesis, structural characterization and third-order non-linear optical property of new three-dimensional metal-organic polymer [Fe2(μ10-btc)0.5(μ2-ox)0.5(μ2-O)1.5]n

One new metal-organic polymer formulated as [Fe₂(μ₁₀-btc)_0.5(μ₂-ox)_0.5(μ₂-O)_1.5]_n 1 (btc = 1,2,4,5-benzenetetracarboxylate, pyramellitate; ox = oxalate) has been synthesized by low-temperature solid-state reaction and characterized by single-crystal X-ray diffraction, elemental analyses, TGA, IR spectra and UV–visible spectra. Complex 1 presents the first 3D coordination network structure constructed by bridging btc, ox and O mixed ligands. In 1, carboxyl groups of btc are all deprotonated and they have a new type of μ₁₀-btc coordination mode. The third-order non-linear optical (NLO) properties of the title compound 1 were also investigated and they exhibit the reverse saturable absorption and self-defocusing performance with modulus of the hyperpolarizability (γ) 5.98 × 10⁻³⁰ esu for 1 in a 7.45 × 10⁻⁴ mol dm⁻³ DMF solution.     

A novel 2D luminescent lead(II) framework with 3-carboxylic acid-4H-1,2,4-triazole based on binuclear Pb2Cl2(H2O)2 building blocks

Under hydrothermal conditions using a triazole derivative ligand 3-carboxylic acid-4H-1,2,4-triazole (HL) and corresponding lead(II) salts, a novel two-dimensional(2D) lead(II) complex {[Pb(L)(μ₂-Cl)(H₂O)}_n (1) has been isolated. In 1 Pb₂Cl₂(H₂O)₂ building blocks can be observed, which are extended by tetra-dentate coordinated L ligands to form a 2D corrugated layered structure. 1 also represents a novel example of luminescent lead(II) frameworks with triazole derivatives. Solid-state fluorescence spectrum of 1 exhibits the excited peak at 376 nm while the emission peak at 604 nm.     

Synthesis, structures, and photoluminescent properties of 3D lanthanide coordination polymers with rare (4,5)-connected topology

Three lanthanide coordination polymers, [Ln(Hpdc)(ox)_0.5(H₂O)₂]·H₂O (Ln = Nd(1), Eu(2), Er(3)) (H₃pdc = 3,5-pyrazoledicarboxylic acid, ox = oxalate), have been synthesized by the hydrothermal reaction of lanthanide nitrates, 3,5-pyrazoledicarboxylic acid, and oxalic acid (H₂ox) and characterized by elemental analysis, IR, and single-crystal X-ray diffraction. Single-crystal X-ray diffraction studies indicate that complexes 1–3 are isomorphous and exhibit three-dimensional metal–organic frameworks with uncommon (4,5)-connected topology, which contain open channels occupied by the lattice water molecules. The photoluminescent properties of complex 2 were also studied.     

Photoinduced linkage isomerism of binuclear bis(pyrazole-3,5-dicarboxylato)-bridged {RuNO} centres

The two novel binuclear pyrazole-3,5-dicarboxylato-bridged {RuNO}⁶ complexes K₂[{Ru(NO)Cl}₂(μ-pzdc)₂] (1) and [{Ru(NO)(H₂O)}₂(μ-pzdc)₂]·4H₂O (2) (pzdc = pyrazole-3,5-dicarboxylate) were synthesized and characterized by elemental analysis, mass spectrometry and spectroscopic methods (NMR, UV–vis, IR). 2 was investigated by means of single-crystal X-ray diffraction analysis. On irradiation, in both 1 and 2 the existence of photoinduced long-lived metastable isonitrosyl states SI were detected by low-temperature infrared spectroscopy.