Syntheses, Characterization and Crystal Structures of Diorganotin(IV) Selenites: 1D Helical Double-Chain Containing Eight-Membered Sn2O4Se2 Inorganic Ring

Three new diorganotin(IV) selenites, [Bu₂Sn(O₂SeC₆H₅OMe)₂]_n (1), [Me₂Sn(O₂SeC₆H₄CHMe₂)₂]_n (2), [Me₂Sn(O₂SeC₆H₄Et)₂]_n (3) have been synthesized and structurally characterized by elemental analysis, FT-IR, NMR (¹H, ¹³C and ¹¹⁹Sn) spectra, TGA, and X-ray crystallography. The X-ray reveals that complexes 1–3 are 1D infinite double-chain polymers. The molecular of complex 1 is further linked by intermolecular C–H···O interactions to form a 2D network polymer. Complex 3 is linked by C–H···O interactions to form a 3D organotin framework.     

New molybdenum(VI) complex with ONS-donor thiosemicarbazone ligand: Preparation,structural characterization,and catalytic applications in olefin epoxidation

New dioxomolybdenum(VI) complex was prepared by reacting 1-(2,4-dihydroxybenzylidene)-N-methyl-N-phenylthiosemicarbazone (H₂L) as ligand and [MoO₂(acac)₂] in acetonitrile solution. The doubly deprotonated ligand is coordinated to molybdenum through sulfur atom, hydrazinic nitrogen atom and phenolic oxygen atom. The resulting complex with the formula [MoO₂L(CH₃CN)] which contains an acetonitrile molecule in sixth site of coordination, was characterized by elemental analyses, ¹H NMR, IR and electronic spectroscopic studies and single crystal X-ray diffraction analysis. This complex was tested as a catalyst for the homogeneous epoxidation of olefins using tert-butyl hydrogen peroxide (TBHP) as an oxidant. The catalyst shows efficient reactivity in the olefins epoxidation reactions giving high yield and selectivity under atmospheric conditions, in most cases.     

Intramolecular hydrogen bond controlled coordination of N-thiophosphorylated thiourea 2,6-Me2C6H3NHC(S)NHP(S)(OiPr)2 with Ni(II)

Reaction of O,O′-diisopropylthiophosphoric acid isothiocyanate (iPrO)₂P(S)NCS with 2,6-dimethylaniline 2,6-Me₂C₆H₃NH₂ leads to the new N-thiophosphorylated thiourea 2,6-Me₂C₆H₃NHC(S)NHP(S)(OiPr)₂ (HL). Reaction of the potassium salt of HL with Ni(II) in aqueous EtOH leads to the complex of formula [Ni(L-N,S)₂]. The molecular structures of the thiourea HL and the complex [Ni(L-N,S)₂] were elucidated by single crystal X-ray diffraction analysis, ¹H and ³¹P NMR spectroscopy and microanalysis. In the complex [Ni(L-N,S)₂], the metal center is found to be in a square-planar N₂S₂ environment formed by the CS sulfur atoms and the P–N nitrogen atoms of two deprotonated L ligands. The ligands are in a trans-configuration.     

Synthesis,crystal structures and urease inhibitory activity of copper(II) complexes with Schiff bases

Two thiocyanate-coordinated Schiff base copper(II) complexes, [CuL¹(NCS)] (1) and [Cu₂(L¹)₂(μ_1,3-NCS)₂]_n (2), where L¹ and L² are the deprotonated forms of 4-bromo-2-[(2-propylaminoethylimino)methyl]phenol (HL¹) and 2-ethoxy-6-[(2-propylaminoethylimino)methyl]phenol (HL²), respectively, have been prepared and structurally characterized. Single crystal X-ray diffraction indicates that 1 is a mononuclear copper(II) complex, while in 2, the adjacent two complex molecules are linked through two phenolate O atoms, forming a dimer. The dimers in 2 are further weakly linked through end-to-end thiocyanate bridges to form a two-dimensional sheet. The Cu atom in 1 is four-coordinate in a square planar geometry, and that in 2 is six-coordinate in an octahedral geometry. Complex 1 shows strong urease inhibitory activity, while complex 2 shows no activity.     

Synthesis and structural characterization of two chain complexes of Mn(II) containing 2-aminopyridinium

The 2-aminopyridine ligand has been exploited in preparation of divalent metal complexes of the formulae [H(2-ampy)][MnCl₃(H₂O)] 1 and [H(2-ampy)]₂[Mn₂Cl₆(2-ampy)₂] 2, where 2-ampy is 2-aminopyridine. Their crystal structures have been determined by X-ray crystallography. Both complexes self-assemble through similar hydrogen bonding motifs which involve three N–H⋯Cl interactions between the 2-aminopyridinium cation and the chloride atoms. Each repeating unit of complexes 1 and 2, [MnCl₃(H₂O)]⁻ and [Mn₂Cl₆(2-ampy)]²⁻, respectively, is doubly edge-sharing to form one-dimensional chains which are cross-linked by hydrogen bonding to the [H(2-ampy)]⁺ cations. In complex 2, two different 2-aminopyridine molecules were observed. One bridges the Mn atoms directly, while the other, through hydrogen bonding interaction, bridges Mn atoms via the chloride atoms. The structural role of the 2-aminopyridinium cation on the aggregation of the metal ions is discussed.     

Nickel(II) thiolates derived from transmetallation reaction of [Zn(Tab)4](PF6)2 with Ni(II) ions and their catalytic activity toward the CN coupling reactions

Reactions of NiCl₂·6H₂O or Ni(ClO₄)₂·6H₂O with 2,2′-bipyridine (2,2′-bipy), or 2-bis(diphenylphosphino)ethane (dppe) or 1,4-bis(diphenylphosphino)butane (dppb) followed by addition of [Zn(Tab)₄](PF₆)₂ (1) resulted in the formation of one trinuclear cationic complex [(2,2′-bipy)₄Ni₃(μ-Tab)₄]Cl_0.5(PF₆)_5.5 (2), one mononuclear cationic complex [Ni(Tab)₂(dppe)](PF₆)₂ (3), and one dinuclear cationic complex [Ni₂(dppb)(μ-Tab)₂(Tab)₂](PF₆)₂(ClO₄)₂ (4). Complexes 2–4 were characterized by elemental analysis, IR, UV–vis, ¹H and ³¹P NMR, and single-crystal X-ray diffraction. In the [(2,2′-bipy)₄Ni₃(μ-Tab)₄]^6 + hexacation of 2, the central Ni(II) atom is connected to two [Ni(2,2′-bipy)₂]^2 + fragments by two pairs of μ-Tab ligands, forming a linear trinuclear cationic structure. The Ni(II) center of the dication of 3 is tetrahedrally coordinated by two S atoms from two Tab ligands and two P atoms of one dppe ligand. Complex 4 has a dimeric cationic structure in which two [(Tab)Ni]^2 + species are linked by a pair of μ-Tab ligands and one dppb ligand. Complexes 2–4 displayed high catalytic activity toward the cross-coupling reactions of arylboronic acids and amines to produce N-arylated amines.     

A fluorescent chemosensor for Zn2 + based on 3,8-bis(4-methoxyphenyl)-1,10-phenanthroline

3,8-Bis(4-methoxyphenyl)-1,10-phenanthroline (L) has been found to show high sensitivity toward Zn^2 + than other competitive metal ions, where Zn^2 +-selective chelation-enhanced fluorescence response at 461 nm is attributed to the formation of a 1:1 metal–ligand complex. In addition, two single-crystal structures of ligand L have been included with the same metal and ligand ratio of 1:1, namely one mononuclear Zn(II) complex [Zn(L)Cl₂] (1) and one 1D Cd(II) coordination polymer [Cd(L)(NO₃)₂]_n (2).     

Self-assembly syntheses and crystal structures of triphenyltin(IV) phenylphosphate: A 1D polymer and a dimer of 24-membered macrocycle

Two novel organotin(IV) complexes of the types [(Ph₃Sn)₄(O₃POPh)₂]_n 1 and [(Ph₃Sn)₆(O₃POPh)₃]₂ 2 have been prepared by treatment of phenylphosphoric acid and the Ph₃SnCl under different conditions. The complexes 1 and 2 were characterized by elemental analysis, IR and NMR (¹H,¹³C,¹¹⁹Sn) spectroscopy and X-ray crystallography diffraction analysis. The structure analyses reveal that complex 1 is an infinite 1D polymer and complex 2 is a dimer which contains two 24-membered macrocycles.     

Tuning the valence of 3,3-di(1H-tetrazol-5-yl)pentanedioic acid: Solvothermal synthesis of Eu(III) and bimetallic Eu(III)/Cu(II) compounds

3,3-Di(1H-tetrazol-5-yl)pentanedioic acid (H₄dtzpda) with four acidic hydrogen atoms can display different valence when reacted with different metal ions. Solvothermal reactions of H₄dtapda with Eu(NO₃)₃·6H₂O or Eu(NO₃)₃·6H₂O/Cu(NO₃)₂·6H₂O afford [Eu(Hdtzpda)(H₂O)₄]·4H₂O (1) and [Eu₂Cu(dtzpda)₂(H₂O)₁₀]·6H₂O (2), respectively, where only three acidic hydrogen atoms of H₄dtzpda are deprotonated in compound 1 while all the four acidic ones are deprotonated in compound 2. In compound 1, Hdtzpda^3 − acts as a pentadentate ligand to bridge Eu(III) centers via the oxygen atoms of the carboxylate group while in compound 2, dtzpda^4 − is a hepadentate one via not only the oxygen atoms of the carboxylate group but also the nitrogen atoms of the tetrazole rings. The luminescence properties of the two compounds in the solid state show both intraligand and characteristic peaks of Eu^3 + at room temperature.     

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.     

Dendrimer-like cyanoruthenate anions with high potential connectivity derived from a [Ru(bpym)3]2+ core

Reaction of [Ru(bpym)₃]²⁺ (bpym = 2,2′-bipyridmidine) with hexacyanoruthenate under forcing conditions affords a mixture of the trinuclear species [(bpym)Ru{(µ-bpym)Ru(CN)₄}₂]^2?, [1]^2?, and the tetranuclear species [Ru{(µ-bpym)Ru(CN)₄}₃]^4?, [2]^4?, in which two or three (respectively) of the peripheral vacant bpym binding sites of [Ru(bpym)₃]²⁺ are occupied by {Ru(CN)₄}^2? fragments. Thus, [1]^2? and [2]^4? have eight and twelve externally-directed cyanide groups respectively for use in forming high connectivity coordination networks. The crystal structure of HK[1]·2MeOH·6.5H₂O reveals a one-dimensional ladder structure in which [1]^2? anions are connected by (i) cyanide/K⁺ and (ii) bpym/K⁺ coordination interactions.     

A mononuclear complex of norfloxacin with silver(I) and its properties

Reaction of norfloxacin (H-Norf) with AgNO₃ yields an unusual mononuclear complex [Ag(H-Norf)₂]NO₃ (1) in which the local coordination environment around Ag⁺ ion is approximately linear with a N–Ag–N angle of 162.1(2)°. Larger concentration of Ag⁺ ions was found in water solution of 1. The unique bonding in 1 may lead to the readily release of Ag⁺ ion from 1, and leads to better antibacterial action in topical burn treatments. Strong blue fluorescent emission of 1 was also observed.     

Self-assembly and guest binding of nickel(II) macrocyclic complex with pentyl groups and cis,cis-1,3,5-cyclohexanetricarboxylic acid

Reaction of the nickel(II) macrocyclic complex 1 including pendant pentyl groups in MeCN/H₂O mixed solvent with deprotonated cis,cis-1,3,5-cyclohexanetricarboxylic acid (CTC^3 −) resulted in two-dimensional (2-D) coordination polymer [Ni(C₁₈H₄₂N₆)]₃[C₆H₉(COO)₃]₂·6H₂O·6CH₃CN (2). The crystal structure of 2 indicates that each nickel(II) macrocyclic unit binds two CTC^3 − ions in trans position and each CTC^3 − ion coordinates three nickel(II) macrocyclic complexes to form a 2-D layer with hexagonal motif. The dried solid of 2 differentiates MeOH, EtOH, and PhOH in toluene solvent with the K_f values of 1.38, 2.11, and 6.68 M^− 1, respectively.     

Synthesis, characterization and crystal structure of a novel co-ordination polymer [Co(BTB)2(NCS)2]n

A novel polymeric cobalt(II) complex with flexible ligand, [Co(BTB)₂(NCS)₂]_n 1 {BTB = 1,4-bis(1,2,4-triazol-1-yl)butane} has been prepared and structurally characterized by single-crystal X-ray diffraction as well as with elemental analysis, infrared spectroscopy and thermogravimetric analysis. The complex 1 consists of two discrete constituents, A and B, with the same chemical formula [Co(BTB)₂(NCS)₂] but different connecting mode. The six-co-ordination of Co²⁺ in A and B is in a distorted octahedral environment formed by four nitrogen atoms of the triazoles and two nitrogen atoms from two trans thiocyanato ligands. The structures of A and B demonstrate a one-dimensional neutral looped chain through two BTB-bridges and a two-dimensional network in which four BTB bridge four Co(II) atoms, respectively. A and B interpenetrate in an inclined fashion. The flexible BTB ligand exhibits three different configurations in 1.     

Construction of a 3D luminescent cadmium(II) network with an unusual deprotonated 1,3-imidazolidine-2-thione ligand

A novel three-dimensional (3D) polymer [Cd(SC₃H₅N₂)₂]_n (SC₃H₅N₂ = deprotonated 1,3-imidazolidine-2-thione) (1) was synthesized. The deprotonated 1,3-imidazolidine-2-thione ligand has been found at cadmium for the first time. The single-crystal X-ray diffraction shows that the deprotonated 1,3-imidazolidine-2-thione ligand contributes greatly to the formation of the 3D framework and the helical structure. Compound 1 exhibits blue fluorescence at 494 nm in the solid state upon excitation at 372 nm.     

Syntheses and structures of two anion-templated dinuclear cadmium complexes with diamino-binaphthyl Schiff bases as ligands

Two cadmium(II) complexes, [CdL¹Cl₂]₂ · 2CH₃OH and [CdL²(SCN)₂]₂ · CH₃OH (1 and 2), were prepared by mixing 2,2′-diamino-1,1′-binaphthalene and 2-pyridyl-carboxaldehyde in the presence of two different cadmium(II) salts. The Schiff base ligand appeared in complex 1 has only one imine group, while in complex 2 both amino groups were reacted to form two imine groups.     

Mono- and dinuclear silver(I) complexes of benzene- and pyridine-bearing 20-membered thiaoxaaza macrocycles

Two 20-membered penta- and hexadentate macrocycles containing one or two pyridine subunits, namely [20]aneNO₂S₂ (L¹) and [20]aneN₂O₂S₂ (L²), have been synthesized. Reaction of L¹ with silver(I) nitrate afforded a unique 2:2 (M:L) disilver(I) complex [μ₂-Ag₂(L¹)₂](NO₃)₂ (1) in which two four-coordinate Ag atoms bridge two ligands to form a cyclic dimer. In contrast, an endo-dentate 1:1 monosilver(I) complexes [AgL²]X; [X = ClO₄ (2) or PF₆ (3)] which show isomorphous structures were obtained from the reactions of L² with silver(I) salts.     

Synthesis and crystal structures of copper(I) iodide complexes chelating with bis(ethylamidophosphine)

Two copper(I) iodide complexes with polydentate bis(ethylamidophosphine) ligands were synthesized, characterized with crystal structures. They include a dimeric complex [Cu(μ-I)(CH₂NHCOC₂H₄PPh₂)₂]₂ 1 containing a planar Cu₂I₂ rhombohedron with two doubly bridged ligands and a tetrameric complex {Cu₄(μ-I)₄[(CH₂NHCOC₂H₄PPh₂)₂]₂} 3 with all the coppers and iodines forming a highly distorted cubane geometry.     

Synthesis,structure and single-molecule magnet characterization of Dy2 dinuclear complexes with an 8–hydroxyquinoline carbohydrazone ligand

The employment of an 8-hydroxyquinoline carbohydrazone tetradentate ligand, 8-hydroxyquinoline-2-carboxaldehyde-(benzoyl)hydrazone (H₂L), DyCl₃·6H₂O and Et₃N has led to the formation of dinuclear Dy(III) complex [Dy₂(HL)₂Cl₄(CH₃OH)₂], (1) and [Dy₂(HL)₂((PhO)₂PO₂)₄]·2(CH₃OH) (2) in the presence of excess amount of bridging diphenyl phosphate anion, (PhO)₂PO^2 −. X-ray crystallography data revealed that two Dy^III atoms in 1 are doubly bridged by the two phenolato oxygen atoms of HL⁻ ligands, however, the Dy^III atoms are bridged by additional two deprotonated μ_1,3-phosphate anions in 2. Each of the two lanthanide ions is eight-coordinated and is located in the different symmetry with triangular dodecahedron (D_2d) for Dy^III in 1 and elongated triangular bipyramid (D_3h) for Dy^III in 2. Dc magnetic susceptibility studies in the 2–300 K range reveal the weak antiferromagnetic interaction for 1 and 2. Both of them showed field-induced slow magnetic relaxation behavior with the U_eff for 1 of 46.0 K higher than 36.8 K for 2.     

Zirconium complexes of amino(polyphenolic) ligands and their hydrolytic stability

Three amino(polyphenolic) ligands, N,N′-bis(5-tert-butyl-2-hydroxybenzyl)-1,2-diaminoethane 1, tris(5-tert-butyl-2-hydroxy-3-methylbenzyl)amine 3, its 3-chloro analogue 4 and their Zr^IV complexes have been synthesised. The crystal structure of the Zr^IV complex of tris(5-tert-butyl-3-chloro-2-hydroxybenzyl)amine, shows this to be [Zr(4-2H)₂] in which both ligands exists in a zwitterionic form with one alkylammonium and three phenolate groups. The complexes are stable in a two phase, chloroform/water, system at high pH, but the zirconium is stripped at pH < 2.5. The pH value needed to strip 50% of the Zr^IV from the complex [Zr(1-4H)] of the tetraphenolic ligand is ∼2.0 whilst the complexes [Zr(3-2H)₂] and [Zr(4-2H)₂] of the triphenolic ligands are slightly more stable with pH_1/2 values of ∼1.4. We were unable to use the ligands to extract zirconium from low pH aqueous zirconium oxychloride solutions into an organic phase under a variety of conditions.