Pillared and open-framework uranyl diphosphonates

The hydrothermal reactions of uranium trioxide, uranyl acetate, or uranyl nitrate with 1,4-benzenebisphosphonic acid in the presence of very small amount of HF at 200 °C results in the formation of three different uranyl diphosphonate compounds, [H₃O]₂{(UO₂)₆[C₆H₄(PO₃)(PO₂OH)]₂[C₆H₄(PO₂OH)₂]₂[C₆H₄(PO₃)₂]}(H₂O)₂ (Ubbp-1), [H₃O]₄{(UO₂)₄[C₆H₄(PO₃)₂]₂F₄}·H₂O (Ubbp-2), and {(UO₂)[C₆H₂F₂(PO₂OH)₂(H₂O)}₂·H₂O (Ubbp-3). The crystal structures of these compounds were determined by single crystal X-ray diffraction experiments. Ubbp-1 consists of UO₇ pentagonal bipyramids that are bridged by the phosphonate moieties to form a three-dimensional pillared structure. Ubbp-2 is composed of UO₅F₂ pentagonal bipyramids that are bridged through the phosphonate oxygen atoms into one-dimensional chains that are cross-linked by the phenyl spacers into a pillared structure. The structure of Ubbp-3 is a three-dimensional open-framework with large channels containing water molecules with internal dimensions of approximately 10.9×10.9 Å. Ubbp-1 and Ubbp-2 fluoresce at room temperature.     

Interaction of copper(II) and palladium(II) with linked 2,2′-dipyridylamine derivatives: Synthetic and structural studies

Interaction of copper(II) salts with 2,2′-dipyridylamine (1), N-cyclohexylmethyl-2,2′-dipyridylamine (2), di-2-pyridylaminomethylbenzene (3), 1,2-bis(di-2-pyridylaminomethyl)-benzene (4), 1,3-bis(di-2-pyridylaminomethyl)benzene (5), 1,4-bis(di-2-pyridylaminomethyl)benzene (6), 1,3,5-tris(di-2-pyridylaminomethyl)benzene (7) and 1,2,4,5-tetrakis(di-2-pyridylaminomethyl)benzene (8) has yielded the following complexes: [Cu(2)(μ-Cl)Cl]₂, [Cu(3)(μ-Cl)Cl]₂ · H₂O, [Cu₂(4)(NO₃)₄], [Cu₂(5)(NO₃)₄] · 2CH₃OH, [Cu₂(6)(CH₃OH)₂(NO₃)₄], [Cu₄(8)](NO₃)₄] · 4H₂O while complexation of palladium(II) with 1, 4, 5 and 6 gave [Pd(1)₂](PF₆)₂ · 2CH₃OH, [Pd₂(4)Cl₄], [Pd₂(4)(OAc)₄], [Pd₂(5)Cl₄], [Pd₂(6)Cl₄] and [Pd₂(6)(OAc)₄] · CH₂Cl₂, respectively. X-ray structures of [Cu(2)(μ-Cl)Cl]₂, [Cu(3)(μ-Cl)Cl]₂ · 2C₂H₅OH, [Cu₂(6)(CH₃OH)₂(NO₃)₄], [Pd(1)₂](PF₆)₂ · 2CH₃OH, [Pd₂(4)(OAc)₄] · 4H₂O and [Pd₂(6)(OAc)₄] · 2CH₂Cl₂ are reported. In part, the inherent flexibility of the respective ligands has resulted in the adoption of a diverse range of coordination geometries and lattice arrangements, with the structures of [Pd₂(4)(OAc)₄] · 4H₂O and [Pd₂(6)(OAc)₄] · 2CH₂Cl₂, incorporating the isomeric ligands 4 and 6, showing some common features. Liquid–liquid (H₂O/CHCl₃) extraction experiments involving copper(II) and 1–3, 5, 7and 8 show that the degree of extraction depends markedly on the number of dpa-subunits (and concomitant lipophilicity) of the ligand employed with the tetrakis-dpa derivative 8 acting as the most efficient extractant of the six ligand systems investigated.     

[(η-C6H6)Ru(L)(Cl/N3/CN/CH3CN)] complexes of non-planar pyrazolylmethylpyridine ligands: Formation of helices due to C-H?X (X = Cl, N) interaction

Structural analysis of a previously reported half-sandwich complex having three-legged “piano-stool” geometry [(η⁶-C₆H₆)Ru^II(L¹)Cl][PF₆] (1) (L¹ = 2-(pyrazol-1-ylmethyl)pyridine) is described. Treatment of 1 with (i) Ag(CF₃SO₃) in CH₃CN and (ii) NaN₃ in CH₃OH, and (iii) the reaction between [(η⁶-C₆H₆)Ru(L²)Cl]-[PF₆] (2) (previously reported) and NaCN in C₂H₅OH led to the isolation of [(η⁶-C₆H₆)Ru(L¹)(CH₃CN)][PF₆]₂ (3), [(η⁶-C₆H₆)Ru(L¹)(N₃)][PF₆] (4), and [(η⁶-C₆H₆)Ru(L²)(CN)][PF₆] (5), respectively (L² = 2-(3,5-dimethyl-pyrazol-1-ylmethyl)pyridine). The complex [(η⁶-C₆H₆)Ru(L⁴)Cl][PF₆] (6) with a new ligand (L⁴ = 2-[3-(4-fluorophenyl)pyrazol-1-ylmethyl]pyridine) has also been synthesized. The structures of 3-6 have been elucidated (¹H NMR spectra; CD₃CN). The molecular structures of 1, 4, and 6·C₆H₅CH₃ have been determined. Notably, the crystal-packing in these structures is governed by C-H?X (X = Cl, N) interactions, generating helical architectures.     

Structural,spectroscopic and redox properties of transition metal complexes of dipyrido[3,2-f:2′,3′-h]-quinoxaline (dpq)

The chemistry of first row transition metal complexes obtained from the ligand dipyrido[3,2-f:2′,3′-h]-quinoxaline (dpq) have been reported. The reaction between Cu(ClO₄)₂ · 6H₂O with dpq under different reaction conditions led to the isolation of three polymorphic copper(II) complexes [Cu(dpq)₂(H₂O)](ClO₄)₂ · H₂O (2), [Cu(dpq)₂(ClO₄)](ClO₄) (3) and [{Cu(dpq)₂(H₂O)}{Cu(dpq)₂(ClO₄)}](ClO₄)₃ (4). The bluish-green compound 2, obtained by reacting Cu(ClO₄)₂ · 6H₂O with dpq in methanol, has a distorted trigonal bipyramidal structure with τ = 0.55. The reaction between Cu(ClO₄)₂ · 6H₂O and dpq in dry acetonitrile produced the blue compound 3 in which the copper(II) centre has a distorted square planar geometry. When the condensation reaction between 1,10-phenanthroline-5,6-dione and 1,2-diaminoethane was carried out in the presence of Cu(ClO₄)₂ · 6H₂O in methanol, the green copper(II) complex 4 was isolated along with 1. The structure determination of 4 has established the presence of two different complex cations in the asymmetric unit and they are considered as co-crystals. In the zinc(II) compound [Zn(dpq)₂(ClO₄)₂] (5), the two perchlorates are unidentately coordinated to the metal centre, providing a distorted octahedral geometry. The quinoxaline ring in 5 is involved in intermolecular π–π interactions, leading to the generation of a sinusoidal chain. The proton NMR spectra, especially those of the paramagnetic complexes [Ni(dpq)₃](ClO₄)₂ (6) and [Co(dpq)₃](ClO₄)₂ (7), have been studied in detail. The electronic absorption spectra and the redox behaviour of the copper(I), copper(II), cobalt(II) and cobalt(III) complexes have been studied. The three copper(II) compounds 2–4 show identical absorption spectra and redox properties when measured in acetonitrile, although in nitromethane they show small but definite differences in their spectral and redox features.     

Synthesis, characterization, and norbornene polymerization of η-benzylnickel(II) complexes of N-heterocyclic carbenes

Neutral η¹-benzylnickel carbene complexes, [Ni(η¹-CH₂C₆H₅)(IiPr)(PMe₃)(Cl)] (3) (IiPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene) and [Ni(η¹-CH₂C₆H₅)(SIiPr)(PMe₃)(Cl)] (4) (SIiPr = 1,3-bis-(2,6-diisopropylphenyl)imidazolin-2-ylidene), were prepared by the reaction between [Ni(η³-CH₂C₆H₅)(PMe₃)(Cl)] and an equivalent amount of the corresponding free N-heterocyclic carbene. The preparation of η³-benzylnickel carbene complexes, [Ni(η³-CH₂C₆H₅)(IiPr)(Cl)] (5) and [Ni(η³-CH₂C₆H₅)(SIiPr)(Cl)] (6) were carried out by the abstraction of PMe₃ from 3 and 4 by the treatment of B(C₆F₅)₃. The treatment of AgX on 5 and 6 produced the anion-exchanged complexes, [Ni(η³-CH₂C₆H₅)(NHC)(X)] (7, NHC = IiPr, X = O₂CCF₃; 8, NHC = IiPr, X = O₃SCF₃; 9, NHC = SIiPr, X = O₂CCF₃; 10, NHC = SIiPr, X = O₃SCF₃). The solid state structures of 3 and 10 were determined by X-ray crystallography. The η³-benzyl complexes of IiPr (5, 7, and 8) alone, in the absence of any activators such as borate and MAO, showed good catalytic activity towards the vinyl-type norbornene polymerization. The catalyst was thermally robust and the activity increases as the temperature rises to 130 °C.     

H-type aggregation of functional metal ion sensing phthalocyanines: Synthesis,characterization and electrochemistry

We report, in this study, the preparation and physical characterization of the peripherally functionalized ionophore ligand, 4,5-bis(6-hydroxyhexan-3ylthio)-1,2-dicyanobenzene (1) and its branched thioalcohol-substituted phthalocyanines, 2,3,7,8,12,13,17,18-octakis{6-hydroxyhexan-3-ylthio)-metal (II) or (III) phthalocyanines {M{Pc[SCH(C₃H₇)(C₂H₅OH)]₈} {M = Pb(II) (2), Zn(II) (3), Cu(II) (4), Co(II) (5) and Mn(III), X = Cl⁻ (6)} which can selectively bind soft-metal ions such as silver (I) and palladium (II). It was observed by means of UV–Vis absorption spectrophotometry that the aggregates formed lead to a low solubility of the phthalocyanines in protic solvents, such as low molecular alcohols. However, the addition of AgNO₃ and Na₂PdCl₄ into a THF–MeOH solution of {M{Pc[SCH(C₃H₇)(C₂H₅OH)]₈X} {M = Pb(II) (2), Zn(II) (3), Cu(II) (4), Co(II) (5) and Mn(III), X = Cl⁻ (6)} induced optical changes, which indicated the formation of twisted H-type dimers (blue shift, face-to-face fashion) of {M{Pc[SCH(C₃H₇)(C₂H₅OH)]₈} complexes, bound by four PdCl₂ and AgNO₃ units in THF solution. Elemental analysis data, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS), FT-IR, ¹H, ¹³C NMR, and UV–Vis spectral data were used as complementary techniques. Voltammetry and in situ spectroelectrochemistry of the complexes were performed on Pt in DMSO/TBAP. The first reduction and oxidation processes of 5 were found to be split due to the presence of facile equilibria between the species coordinated differently at axial positions. The Mn(III)Pc(−2)X⁻ complex (6) displayed well-defined colour changes during its reduction processes. The redox behaviour of the Mn(III)Pc(−2)X⁻ complex was observed to be affected significantly by the existence of oxygen in solution due to the formation of μ-oxo MnPc species, Mn(III)Pc–O–PcMn(III). This effect was clarified well by in situ spectroelectrochemical measurements.     

Syntheses and NMR study of [(2-dimethylaminomethyl)phenyl]vinylsilane derivatives and [(2-dimethylaminomethyl)phenyl]ethylsilane derivatives

Various vinylsilanes, SiX(CHCH₂)(CH₃)[2-(CH₃)₂NCH₂C₆H₄], and ethylsilanes, SiX(CH₂CH₃)(CH₃)[2-(CH₃)₂NCH₂C₆H₄] [X=Cl (1); OMe (2); H (3); F (4); OSiMe₃ (5); NMe₂ (6); Me (7)], were synthesized in order to investigate the electronic effect of vinyl group on silicon atom having an intramolecular coordination arm. The magnitude of Δδ (ethyl→vinyl for ²⁹Si-NMR) of chlorosilane, 1, was the biggest one among 1-7. The differences of ²⁹Si chemical shifts between vinylsilanes and ethylsilanes increased in the following order: X=Me, NMe₂<H<OSiMe₃<OMe<F<Cl.     

Copper(II) complexes with neutral bis(pyrazolyl)methane ligands: The influence of steric hindrance on their structures and properties

By using the neutral bidentate nitrogen-containing ligands; bis(3,5-dimethyl-1-pyrazolyl)methane (L0″), bis(3,5-diisopropyl-1-pyrazolyl)methane (L1″), bis(3-tertiary-butyl-5-isopropyl-1-pyrazolyl)methane (L3″), and bis(3,5-ditertiary-butyl-1-pyrazolyl)methane (L4″), the copper(II) nitrato complexes [Cu(L0″)₂(NO₃)]NO₃ (1NO₃), [Cu(L0″)(NO₃)₂] (2), [Cu(L1″)(NO₃)₂] (3), [Cu(L3″)(NO₃)₂] (4), and [Cu(L4″)(NO₃)₂] (5), chloro complexes [Cu(L0″)₂Cl]₂(CuCl₄) (6CuCl₄), [Cu(L0″)₂Cl]₂(Cu₂Cl₆) (6Cu₂Cl₆), [Cu(L1″)Cl₂] (7), and [Cu(L3″)Cl₂] (8), nitrito complexes [Cu(L0″)(ONO)₂] (9) and [Cu(L1″)(ONO)₂] (10), and the complexes with perchlorate ions [Cu(L0″)₂(CH₃OH)](ClO₄)₂ (11ClO₄) and [Cu(L1″)₂(H₂O)](ClO₄)₂ (12ClO₄) were systematically synthesized and fully characterized by X-ray crystallography and by IR, far-IR, UV–Vis absorption, and ESR spectroscopy. In comparison with the obtained complexes with four bis(pyrazolyl)methanes having different bulkiness at pyrazolyl rings, the second coordination sphere effects on the ligands are discussed in detail. Moreover, the structures and physicochemical properties of these obtained complexes are compared with those of the related complexes with the neutral tridentate tris(pyrazolyl)methane ligand.     

Dinuclear double-helical cobalt complexes with two-armed terdentate ligands: Synthesis,structure and physical properties

Three ligands with flexible bis-terdentate coordination sites, di(2-pyridylcarbaldehyde)-6,6′-dicarboxylic acid hydrazone-2,2′-bipyridine (H₂L¹), di(2-acetylpyridyl)-6,6′-dicarboxylic acid hydrazone-2,2′-bipyridine (H₂L²) and di(2-pyridylketone)-6,6′-dicarboxylic acid hydrazone-2,2′-bipyridine (H₂L³) have been easily prepared. Dinuclear double-stranded helicates Co₂(L¹)₂(ClO₄)₂(C₂H₅OH)₂(H₂O)₂ (1), Co₂(HL²)(L²)(ClO₄)₃(C₂H₅OH)₂(H₂O)₂ (2) and Co₂(HL³)(L³)(ClO₄)₃(H₂O)₄ (3) based on the ligands, H₂L^1–3, respectively, have been obtained via self-assembly, their structures were determined by FT-IR, Elemental Analysis, ESI-MS and X-ray diffraction method.     

Dimethylthallium(III) complexes with picolinic acid and its hydroxyl derivatives

The reaction of dimethylthallium(III) hydroxide with picolinic acid (Hpic), 3-hydroxypicolinic acid (H₂3hpic) and 6-hydroxypicolinic acid (H₂6hpic) in an aqueous/methanol mixture afforded the complexes [TlMe₂(pic)] (1), [TlMe₂(H3hpic)] (2) and [TlMe₂(H6hpic)] (3), respectively. Complex 3′, [NaTlMe₂(6hpic)₂]_n, was obtained as a minor product from a methanolic solution of 3. Compounds 1–3 were characterized by IR and Raman spectroscopy and, in the cases of 1, 2 and 3′, by single-crystal X-ray diffraction. Complex 3′ is the first example of an H6hpic⁻ heterobimetallic compound to be isolated. The ¹H and ¹³C NMR spectra of 1 and 2 are also discussed.     

Ruthenium(II), copper(I) and silver(I) complexes of large bite bisphosphinite, bis(2-diphenylphosphinoxynaphthalen-1-yl)methane: Application of Ru(II) complexes towards the hydrogenation of styrene and phenylacetylene

Ruthenium(II), copper(I) and silver(I) complexes of large bite bisphosphinite Ph₂P{(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)}PPh₂ (1) are described. Reactions of bisphosphinite 1 with [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂ and RuCl₂(PPh₃)₃ afford mono- and bis-chelate complexes [RuCl(η⁶-p-cymene){η²-Ph₂P{(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)}PPh₂-κP,κP}]Cl (2) and trans-[RuCl₂{η²-Ph₂P{(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)}PPh₂-κP,κP}₂] (3), respectively. Treatment of 1 with CuX (X = Cl, Br and I) furnish 10-membered chelate complexes of the type [Cu(X){η²-Ph₂P(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)PPh₂-κP,κP}] (4, X = Cl; 5, X = Br; 6, X = I), whereas [Cu(MeCN)₄]PF₆ affords a bis-chelated cationic complex [Cu{η²-Ph₂P(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)PPh₂-κP,κP}₂][PF₆] (7). Reaction between 1 and AgOTf produce both mono- and bis-chelated complexes [Ag{η²-Ph₂P(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)PPh₂-κP,κP}(SO₃CF₃)] (8) and [Ag{η²-Ph₂P(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)PPh₂-κP,κP}₂][SO₃CF₃] (9), respectively; whereas the similar reaction of 1 with[Ag(OTf)PPh₃] affords chelate complex of the type [Ag{η²-Ph₂P(-OC₁₀H₆)(μ-CH₂)(C₁₀H₆O-)PPh₂-κP,κP}(PPh₃)(SO₃CF₃)] (10). All the complexes were characterized by ¹H NMR, ³¹P NMR, elemental analysis and mass spectrometry, including low-temperature NMR studies in the case of silver complexes. The molecular structures of 4 and 6 are determined by X-ray diffraction studies. Ruthenium complexes 2 and 3 promote catalytic hydrogenation of styrene and phenylacetylene with good turnover numbers.     

Macrocyclic organotin(IV) carboxylates based on benzenedicarboxylic acid derivatives: Syntheses, crystal structures and antitumor activities

Six new organotin carboxylates based on 1,3-benzenedicarboxylic acid and 1,4-benzenedicarboxylic acid derivatives, namely (Ph₃Sn)₂(2,5-L¹)(C₂H₅OH)₂ (1) (2,5-H₂L¹ = 2,5-dibenzoylterephthalic acid), (Ph₃Sn)₂(2,5-L²)(C₂H₅OH)₂ (2) (2,5-H₂L² = 2,5-bis(4-methylbenzoyl)terephthalic acid), (Ph₃Sn)₂(2,5-L³)(C₂H₅OH)₂ (3) (2,5-H₂L³ = 2,5-bis(4-ethylbenzoyl)terephthalic acid), [(n-Bu₂Sn)₄(4,6-L¹)O₂(OH)(OC₂H₅)]₂·2(C₂H₅OH) (4) (4,6- H₂L¹ = 4,6-dibenzoylisophthalic acid), [(n-Bu₂Sn)₄(4,6-L¹)O₂(OH)(OC₄H₉)]₂·2(C₄H₉OH) (5) and [(n-Bu₂Sn)₄(4,6-L²)O₂(OH)(OC₂H₅)]₂·2(C₂H₅OH) (6) (4,6-H₂L² = 4,6-bis(4-methylbenzoyl)isophthalic acid), have been synthesized. All the organotin carboxylates have been characterized by elemental analysis, IR, ¹H and ¹³C NMR spectroscopy and X-ray crystallography diffraction analyses. The structural analysis reveals that complexes 1-3 show similar structures, containing binuclear triorganotin skeletons. The significant intermolecular O-H?O hydrogen bonds linked the complexes 1-3 to form a novel 2D network polymer with 38-member macrocycles. In complexes 4-6, two Sn₄O₄ ladders are connected by two 1,3-benzenedicarboxylic acid derivatives to yield ladder-like octanuclear architectures and form macrocycle with 24 atoms. In addition, the antitumor activities of complexes 1-6 have been studied.     

Synthesis and characterisation of saturated and unsaturated triruthenium clusters containing electronically symmetrical and asymmetrical alkynes

The synthesis and characterisation of μ₃-η²-alkynyl triruthenium clusters, [Ru₃(μ₃-η²-R¹-4-C₆H₄CCR²)(μ-dppm)(μ-CO)(CO)₇] (1, saturated), [Ru₃(μ₃-η²-R¹-4-C₆H₄CCR²)(μ-dppm)(CO)₇] (2, unsaturated) and [Ru₃(μ₃-η²-R¹-4-C₆H₄CCR²)(μ-dppm)(PPh₃)(CO)₇] (3, saturated) containing symmetrical and asymmetrical alkynes in which R¹ and R² are electron donor or electron withdrawing groups in the para position of the aromatic ring(s) or R² is ferrocenyl, are reported. Clusters 1 were obtained from the reactions of [PPN][Ru₃(μ-Cl)(CO)₁₀] with R¹-4-C₆H₄CCR² and dppm. Clusters 1 were successfully decarbonylated to give unsturated clusters 2, with the exception of the FcCCC₆H₄-4-NO₂ containing cluster, which is stable. Novel adducts 3 were obtained in high yields by addition of PPh₃ to unsaturated clusters 2. Clusters 1-3 were characterised by analytical and spectroscopic data, and structures were proposed on the basis of systematic ³¹P NMR studies and correlations with X-ray structural data of related compounds available in the literature. Saturated compounds 1 contain a CO and a dppm ligands bridging the same edge, which is also parallel to the μ₃-η²-alkyne, as opposed to the structure previously proposed for the PhCCPh and other derivatives, and established by X-ray crystallography for the PhCCCCPh cluster derivative, in which the dppm ligand bridges a different edge. Unsaturated compounds 2 exhibit the same structure established for the PhCCPh derivative in the solid state, with the alkyne bonded in the μ₃-η²-mode perpendicular to the Ru₂ edge supported by the dppm ligand. Because the dppm phosphorus chemical shifts were sensitive to the alkyne electronic asymmetry, it was possible to show that clusters containing electronically asymmetrical alkynes exist in two inseparable isomeric forms, which differ with respect to the alkyne orientation. Similarly to their osmium analogues, saturated compounds 3 exist as inseparable mixtures of isomers that differ with respect to the position of the bridging CO and dppm ligands, and in the cases of asymmetrical alkyne derivatives, also with respect to the orientation of the alkyne. This work has established, therefore, that μ-CO and dppm ligand positions respective to the μ₃-η²-alkyne in saturated clusters 1 and 3 are sensitive both to the nature of the coordinated alkyne and to the presence of a PPh₃ in place of a CO ligand on the metal frame.     

Iron,copper and zinc ammonium-1-hydroxyalkylidene-diphosphonates with zero-, one- and two-dimensional covalent metal–ligand structures extended into three-dimensional supramolecular networks by charge-assisted hydrogen-bonding

Hydrothermal synthesis with MCl₂ (M = Fe, Cu, and Zn) and disodium 5-ammonium-1-hydroxypentylidene-1,1-bisphosphonate, (Na⁺)₂[⁺H₃N(CH₂)₄C(OH)(PO₃²⁻)(PO₃H⁻)] (Na₂HAC₅OHP₂) or sodium 3-ammonium-1-hydroxypropylidene-1,1-bisphosphonate hydrate, Na⁺[⁺H₃N(CH₂)₂C(OH)(PO₃H^–)(PO₃H^–)]·H₂O (NaH₂PAM·H₂O) the sodium salt of pamidronic acid, H₃PAM) yielded the one-dimensional (1D) iron, molecular copper and two-dimensional (2D) zinc compounds 1D-{[Fe(μ₃-η⁵-HAC₅OHP₂)]·H₂O}, 1, [Cu(η²-H₂AC₅OHP₂)₂], 2, 2D-{[Zn₂(μ₅-η⁷-AC₅OHP₂)Cl], 3, and 2D-{[Zn(μ₂-η³-H₂PAM)₂], 4, respectively. The bisphosphonate ligand bridges (μ_n) between 2–5 metal atoms and uses 2–7 oxygen donor atoms towards metal coordination (ηⁿ). The zwitterionic nature of the now bis- or tetrakis-deprotonated ammonium–bisphosphonate is retained in the metal complexes. From the reaction of NiCl₂ and Na₂HAC₅OHP₂ the zwitterionic 5-ammonium-1-hydroxypentylidene-1-phosphonic acid, ⁺H₃N(CH₂)₄CH(OH)PO₃H⁻, 5 was obtained as a product of the ligand P–C bond hydrolysis. Adjacent strands, molecules or layers in 1–4, respectively are organized through the Coulomb attraction between the positive ammonium group and the negative phosphonate groups, supported by hydrogen-bonding. Each protic H atom on the C–OH, NH₃⁺ and –PO₃H⁻ group is involved in charge-assisted hydrogen-bonding. The ammonium-pentylidene groups act as hydrophobic separators between the hydrophilic units with the polar M{C(OH)(PO₃)₂} and {NH₃} units. Bond valence sum calculations support the Fe(II) oxidation state in 1, which was experimentally determined from a quantitative polarographic Fe(II)/Fe(III) speciation analysis as well as a temperature variable magnetic study.     

Self assembly of asymmetric tetranuclear Cu(II) [2 × 2] grid-like complexes and of a dinuclear Ni(II) complex from pyridyl-phenol Schiff base ligands

Self assembly of N-salicylidene 2-aminopyridine (L1H) with Cu(NO₃)₂·3H₂O affords [Cu₄(L1)₄(NO₃)₃(CH₃OH)][Cu(L1)(NO₃)₂](2-aminopyridinium)(NO₃)·5CH₃OH (1) which is composed of an asymmetric [2 × 2] grid-like cationic complex that co-crystallizes with a Cu(II) mononuclear anion. This remarkable tetranuclear unit presents three penta-coordinated and one hexa-coordinated Cu(II) sites. This quadruple helicate structure reveals strong anti-ferromagnetic coupling (J = −340(2) cm⁻¹) between Cu(II) ions through a double alkoxo bridge. Reacting L1H with Cu(NO₃)₂·3H₂O in slightly different conditions affords however a more symmetric tetranuclear grid-like complex: [Cu₄(L1)₄(NO₃)₂(OH)₂](2-aminopyridinium)(OH)·CH₃OH) (2). A dinuclear Ni(II) complex, [Ni₂(L2)₂(L2H)₂(NCS)₂(CH₃OH)₂]·2CH₃OH (3), obtained with another related donor ligand (L2H = N-salicylidene 3-aminomethylpyridine) was also prepared.     

Syntheses, structures and catalytic activity of copper(II) complexes with hydroxyindanimine ligands

A series of new hydroxyindanimine ligands [ArNCC₂H₃(CH₃)C₆H₂(R)OH] (Ar = 2,6-i-Pr₂C₆H₃, R = H (HL¹), R = Cl (HL²), and R = Me (HL³)) were synthesized and characterized. Reaction of hydroxyindanimine with Cu(OAc)₂ · H₂O results in the formation of the mononuclear bis(hydroxyindaniminato)copper(II) complexes Cu[ArNCC₂H₃(CH₃)C₆H₂(R)O]₂ (Ar = 2,6-i-Pr₂C₆H₃, R = H (1), R = Cl (2), and R = Me (3)). The complex 2′ was obtained from the chlorobenzene solution of the complex 2, which has the same molecule formula with the complex 2 but it is a polymorph. All copper(II) complexes were characterized by their IR and elemental analyses. In addition, X-ray structure analyses were performed for complexes 1, 2, and 2′. After being activated with methylaluminoxane (MAO), complexes 1-3 can be used as catalysts for the vinyl polymerization of norbornene with moderate catalytic activities. Catalytic activities and the molecular weight of polynorbornene have been investigated for various reaction conditions.     

Dinuclear copper(I) complexes of tris(3,5-dimethylpyrazol-1-yl)methane: Synthesis, structure, and reactivity

The reaction of [Cu(NCMe)₄](BF₄) with equimolar amounts of the tris(substituted-pyrazolyl)methane ligand HCPz₃ or HC(3,5-Me₂Pz)₃ yields the respective salts [Cu(HCPz₃)(NCMe)](BF₄) (1a) or [Cu(HC(3,5-Me₂Pz)₃)(NCMe)](BF₄) (1). The acetonitrile ligand of 1 can be replaced by prazine, 4,4′-dipyridine or 1,4-diisocyanobenzene to yield related mononuclear complexes [Cu(HC(3,5-Me₂Pz)₃)(pyrazine)](BF₄) (2), [Cu(HC(3,5-Me₂Pz)₃)(4,4′-bipyridine)] (BF₄) (3) or [Cu(HC(3,5-Me₂Pz)₃)(1,4- CNC₆H₄NC)](BF₄) (7), respectively. A series of binuclear copper(I) complexes {[Cu(HC(3,5-Me₂Pz)₃)]₂(μ -BL)}(BF₄)₂ (4, BL = pyrazine; 5, BL = 4,4′-dipyridine; 8, BL = 1,4-diisocyanobenzene) were prepared by treating equal molar ratio of 1 with related mononuclear complexes 2, 3 and 7. In addition, binuclear copper(I) complexes were also prepared from treatment of 2 equiv of 1 with the related bridge ligand. Both of 4 and 5 reformed mononuclear starting complex 1 in acetonitrile solution. However, the more robust complex 8 was stable in acetonitrile solutions. The structure of complexes 1a, 4, 5, and 7 were confirmed by X-ray crystallography. The redox properties of 4 and 8 were examined by cyclic voltammetry and exhibited two quasi-reversible waves suggesting that no significant structural reorganization occurs during the redox process on the electrochemical time scale.     

New organically templated gallium oxalate-phosphate structures based on Ga4(PO4)4(C2O4) building unit

Five organic-inorganic hybrid gallium oxalate-phosphates, [Ga₂(PO₄)₂(H₂O)(C₂O₄)_0.5](C₃N₂H₁₂)_0.5(H₂O) (1), [Ga₂(PO₄)₂(C₂O₄)_0.5](C₂N₂H₁₀)_0.5(H₂O) (2), [Ga₂(PO₄)₂(C₂O₄)_0.5](C₃N₂H₁₂)_0.5 (3), [Ga₂(PO₄)₂(H₂PO₄)_0.5(C₂O₄)_0.5](C₄N₃H₁₆)_0.5 (H₂O)_1.5 (4) and [Ga_2.5(PO₄)_2.5(H₂O)_1.5(C₂O₄)_0.5](C₄N₃H₁₅)_0.5 (5), have been synthesized by using 1,3-diaminopropane, ethylenediamine and diethylene triamine as structure-directing agents under hydrothermal condition. The structures of 1-5 are based on Ga₄(PO₄)₄(C₂O₄) building unit made up from Ga₂O₈(C₂O₄) oxalate-bridging dimer and alternating PO₄ and GaO₄ tetrahedral units. Compound 1 is layered structure where the building units link together in the same orientation. Corner sharing of these similar layers result in three-dimensional (3-D) structure 2. However, in compound 3, the building units arrange in a wave-like way to generate two types of eight member ring (8MR) channels. Both 4 and 5 contain the layers where the building units have an opposite orientation. Those layers are linked by H₂PO₄ group and Ga(PO₄)(H₂O)₃ cluster, respectively, to form 3-D frameworks with 12MR large pore channels. Compounds 2-5 exhibit intersecting 3-D channels where the protoned amines are located.     

Exploring the reactivity of an N-pyrazole, P-phosphine hybrid ligand with Cu(I), Ag(I) and Au(I) precursors

The reactivity of (3,5-dimethyl-1H-pyrazol-1-yl)ethyldiphenylphosphine (L) hybrid ligand against Cu(I), Ag(I) and Au(I) has been assayed and compounds [Cu(L)₂](PF₆) (1), [Ag(L)]₂(PF₆)₂·2C₂H₄Cl₂·2C₄H₁₀O (2) and [AuCl(L)]₂ (3) have been isolated and fully characterised. A fully characterisation by analytical and spectroscopic methods of 1-3 are presented and X-ray crystal structures of 1 and 2 are also reported. The similar data obtained between 2 and 3 permits to do a serious purpose of the structure of 3 in solid and solution.