Synthesis, crystal structure and vibrational spectroscopy of a novel mixed ligands Ni(II) pentaborate: [Ni(C4H10N2)(C2H8N2)2][B5O6(OH)4]2

A novel organic-inorganic hybrid pentaborate [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂][B₅O₆(OH)₄]₂ has been synthesized by hydrothermal reaction and characterized by FT-IR, Raman spectroscopy, elemental analyses and DTA-TGA. Its crystal structure was determined from single crystal X-ray diffraction. The structure consists of isolated polyborate anion [B₅O₆(OH)₄]⁻ and nickel complex cation of [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂]²⁺, in which the two kinds of ligands come from the decomposition of triethylenetriamine material. The [B₅O₆(OH)₄]⁻ units are connected to one another through hydrogen bonds, forming a three-dimensional framework with large channel along the a and c axes, in which the templating [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂]²⁺ cations are located. The assignments of the record FT-IR absorption frequencies and Raman shifts were given.     

Copper(I)-organophosphine complexes of bis(3,5-dimethylpyrazol-1-yl)dithioacetate ligand

Copper(I) complexes have been synthesized from the reaction of CuCl, monodentate tertiary phosphines PR₃ (PR₃ = P(C₆H₅)₃; P(C₆H₅)₂(4-C₆H₄COOH); P(C₆H₅)₂(2-C₆H₄COOH); PTA, 1,3,5-triaza-7-phosphaadamantane; P(CH₂OH)₃, tris(hydroxymethyl)phosphine) and lithium bis(3,5-dimethylpyrazolyl)dithioacetate, Li[LCS₂]. Mono-nuclear complexes of the type [LCS₂]Cu[PR₃] have been obtained and characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (¹H, ¹³C and ³¹P) NMR spectral data; in these complexes the ligand behaves as a κ³-N,N,S scorpionate system. One exception to this stoichiometry was observed in the complex [LCS₂]Cu[P(CH₂OH)₃]₂, where two phosphine co-ligands are coordinated to the copper(I) centre. The solid-state X-ray crystal structure of [LCS₂]Cu[P(C₆H₅)₃] has been determined. The [LCS₂]Cu[P(C₆H₅)₃] complex has a pseudo tetrahedral copper site where the bis(3,5-dimethylpyrazolyl)dithioacetate ligand acts as a κ³-N,N,S donor.     

Supramolecular networks of transition metal sulfates templated by piperazine

Syntheses, structural studies from single-crystal X-ray diffraction and thermal behaviour of (C₄H₁₂N₂)[M^II(H₂O)₆](SO₄)₂ with M^II = Mn, Ni, Fe and Cu are reported. All compounds crystallise in monoclinic system, space group P2₁/n. The two isotypical compounds (C₄H₁₂N₂)[Mn(H₂O)₆](SO₄)₂ (I) and (C₄H₁₂N₂)[Ni(H₂O)₆](SO₄)₂ (II), are isostructural with the related cobalt and zinc phases, while the isotypical sulfates (C₄H₁₂N₂)[Fe(H₂O)₆](SO₄)₂ (III) and (C₄H₁₂N₂)[Cu(H₂O)₆](SO₄)₂ (IV) belong to another structure type. The three-dimensional structure networks for the four compounds consist of isolated [M^II(H₂O)₆]²⁺ and (C₄H₁₂N₂)²⁺ cations and (SO₄)²⁻ anions linked by hydrogen-bonds only. The thermal behaviour of the precursors has been studied by powder thermodiffractometry and thermogravimetric analyses. The first stages of dehydration are discussed with respect to the hydrogen bonds within the compounds.     

Synthesis and structural investigations of Ni(II)- and Pd(II)-coordinated α-diimines with chlorinated backbones

Novel square planar Pd(II) α-diimines [PdX₂{ArNC(Cl)}₂], where Ar = C₆H₅, (2,6-Me₂C₆H₃), (2,6-ⁱPr₂C₆H₃) and X = Cl or Br, and the octahedral Ni(II) complex [NiBr₂{(C₆H₅)NC(Cl)}₂(THF)₂] have been prepared and characterised by spectroscopic methods. For two of the Pd(II) complexes and the Ni(II) complex the crystal structures were determined by X-ray crystallography. A further insight into the geometry and electronic structure of [PdBr₂{(2,6-Me₂C₆H₃)NC(Cl)}₂] was gained using density functional theoretical calculations (DFT). This compound resembles structurally and electronically typical olefin polymerisation pre-catalysts supported by α-diimines incorporating methyl- and 1,8-naphtalenyl substituents at the ligand backbone. The chlorine-substituted backbone of the free ligand [2,6-Me₂C₆H₃NC(Cl)]₂ can be employed in further alkylation reactions to generate new multifunctional ligand prototypes with potential uses as ansa-metallocene/diimines building blocks for catalytic applications of heterobimetallic complexes.     

Novel ruthenium(II) diamine complexes

The complex cations [Ru(C₇H₁₆N₂)(C₁₀H₁₄)Cl]⁺, [Ru(C₇H₁₆N₂)(C₆H₆)Cl]⁺, [Ru(C₉H₁₈N₂)(C₆H₆)Cl]⁺, [Ru(C₉H₁₈N₂)(C₁₀H₁₄)Cl]⁺ and [Ru(C₁₄H₁₆N₂)(C₁₀H₁₄)Cl]⁺ have been synthesised from the reaction between the ruthenium-arene complexes [with C₆H₆ (benzene) or C₁₀H₁₄ (p-cymene)] and the respective chiral diamines [C₇H₁₆N₂=(S)-(−)-2-aminomethyl-1-ethylpyrrolidine, C₉H₁₈N₂=(S)-(+)-2-(pyrrolidinylmethyl)-pyrrolidine, or C₁₄H₁₆N₂=(1R,2R)-(+)-1,2-diphenylethylenediamine], isolated and characterised as chloride salts using single-crystal X-ray diffraction. All complexes were fully characterised by elemental analysis, mass spectrometry, ¹³C and ¹H NMR, and also found to exhibit catalytic activity in the transfer hydrogenation of acetophenone to 1-phenylethanol at 50 °C (enantiomeric excesses range from ca. 25% to 60%, and conversions from ca. 30% to 50%).     

Synthesis and characterization of carbamoyl methyl pyrazole(CMPz) compounds of palladium(II) chloride: The crystal and molecular structure of [PdCl2{C3H3N2CH2CONBu2}2]

Carbamoyl methyl pyrazole compound of palladium(II) chloride of the type [PdCl₂L₂] (where L =  C₅H₇N₂CH₂CON(C₄H₉)₂, C₅H₇N₂CH₂CON(ⁱC₄H₉)₂, C₃H₃N₂CH₂CON(C₄H₉)₂, or C₃H₃N₂CH₂CON(ⁱC₄H₉)₂) has been synthesized and characterized by IR and ¹H NMR spectroscopy. The structure of the compound [PdCl₂{C₃H₃N₂CH₂CONⁱBu₂}₂] has been determined by single crystal X-ray diffraction and shows that the ligands are bonded through the soft pyrazolyl nitrogen atom to the palladium(II) chloride in a trans disposition.     

The crystallochemistry of tetracyanocomplexes. The crystal and molecular structures of tris(1,2-diaminoethane)zinc(II) tetracyanoniccolate(II) monohydrate and tris(1,2-diaminoethane)zinc(II) tetracyanoniccolate(II)

C₁₀H₂₆N₁₀ONiZn, tris(1,2-diaminoethane) zinc(II) tetrakis(cyano)niccolate(II) monohydrate (I), orthorhombic, Pbca, a = 1.1680(4), b = 1.5844(3), c = 1.9981(6) nm, Z = 8 d(meas) = 1.54, d(calc) = 1.53 g cm^?3. C₁₀H₂₄N₁₀NiZn, tris(1,2-diaminoethane) zinc(II) terakis(cyano)niccolate(II), (II), monoclinic, P2₁/n, a = 0.7957(2), b = 1.5170(5), c = 1.4932(4) nm, β = 96.41(2)°, Z = 4, d(meas) = 1.49, d(calc) = 1.51 g cm^?3. Both the structures (I) and (II) have been solved by the heavy atom method and refined by full-matrix least-squares to R(I) = 0.086 for 1890 independent reflections and R(II) = 0.058 for 1689 independent reflections, respectively. In the case of (II) the superlattice structure problem was solved. The crystal structure of (I) consists of [Zn(en)₃]²⁺ cations, [Ni(CN)₄]^2? anions and water molecules. Two of the cyano groups in trans positions are bonded to water molecules by hydrogen bonds, the distances CN?O being 0.289 and 0.291 nm, respectively. The crystal structure of (II) is constituted by [Zn(en)₃]²⁺ cations and [Ni(CN)₄]^2? anions.     

Chalcogenolato-bridged cyclometallated binuclear palladium complexes: Synthesis, spectroscopy, structures of [Pd2(μ-Cl)(μ-SMes)(C10H6NMe2-C,N)2] and [Pd2(μ-SePh)2(C10H6NMe2-C,N)2]

Reactions of orthometallated binuclear palladium complexes with NaER, obtained by NaBH₄ reduction of R₂E₂ in methanol, gave complexes, [Pd₂(μ-ER)₂(C^∩Y)₂] (HC^∩Y = N,N-dimethylbenzylamine (C₆H₅CH₂NMe₂), N,N-dimethylnaphthylamine (C₁₀H₇NMe₂), tri-o-tolylphosphine {P(tol-o)₃}; ER=SePh, SeMes, TePh, TeMes (Mes = 2,4,6-Me₃C₆H₂). Similar reactions of [Pd₂(μ-Cl)₂(C₁₀H₆NMe₂-C,N)₂] with Pb(SMes)₂ or MesSH in the presence of NaHCO₃ gave chloro/thiolato-bridged complex [Pd₂(μ-Cl)(μ-SMes)(C₁₀H₆NMe₂-C,N)₂]. The newly synthesized complexes were characterized by elemental analysis, UV-Vis, IR, NMR (¹H, ¹³C, ³¹P, ⁷⁷Se, ¹²⁵Te) spectroscopy. These complexes crystallized out preferentially in sym-cis configuration. A low energy charge transfer transition has been identified from chalcogenolate centers to an emptyπ^∗ orbital of cyclometallated ligand in absorption spectroscopy in these complexes. The structures of [Pd₂(μ-Cl)(μ-SMes)(C₁₀H₆NMe₂-C,N)₂] (1) and [Pd₂(μ-SePh)₂(C₁₀H₆NMe₂-C,N) ₂] (3) have been established by single crystal X-ray diffraction analyses. In the former, the two palladium atoms are held together by chloro and thiolato bridges whereas in the latter, the two phenylselenolato ligands bridge two palladium atoms. The pyrolysis of [Pd(μ-TeMes)(C₁₀H₆NMe₂-C,N)]₂ (10) in a furnace gave Pd₇Te₃ whereas thermolysis in TOPO afforded primarily PdTe₂.     

Copper(II) compounds of the planar-tridentate ligand 2,6-bis(pyrazol-3-yl)pyridine

The tridentate ligand 2,6-bis(pyrazol-3-yl)pyridine (dPzPy) renders coordination compounds with halide, nitrate and tetrafluoroborate salts of copper. The complexes, which have the form [Cu(dPzPy)X₂] with X=Br and Cl, [Cu(dPzPy)(NO₃)₂](H₂O), and [Cu(dPzPy)₂](BF₄)(SiF₆)_0.5(MeOH)₃ have been characterized by elemental analysis and by IR, EPR and ligand field spectroscopy. The single-crystal X-ray structure of [Cu(C₁₁H₉N₅)Br₂] shows the copper(II) ion to be coordinated by three N atoms of 2,6-bis(pyrazol-3-yl)pyridine and two bromides in a geometry exactly in between a trigonal-bipyramid and a square-pyramid. Each molecule lies on a crystallographic C₂-symmetry axis. They are coupled to one another by a two-dimensional network through NH to Br hydrogen bonds. The crystal structure of [Cu(C₁₁H₉N₅)Cl₂] is analogous to the bromide. The single-crystal X-ray structure of [Cu(dPzPy)₂](BF₄)(SiF₆)_0.5(MeOH)₃ shows the copper ion to be in a Jahn-Teller distorted octahedral N₆ environment of two mer-oriented tridentate ligands.     

Oligonuclear nickel(II) complexes sustained by intermolecular hydrogen-bonding

Reaction of Ni(OAc)₂ with the symmetric `end-off' compartmental proligand 2,6-[N,N^′-bis(2-hydroxy-phenylmethyl)-N,N^′-bis(2-pyridylmethyl)aminomethyl]-4-methylphenol (H₃L) in the presence of NaPF₆ has been found to generate a homotetranuclear nickel(II) complex [(Ni₄HL)(L)(OAc)₂(H₂O)₂(HOAc)₂]PF₆. The crystal structure of the complex reveals that the complex is donor asymmetric and that the extended supra-ligand periphery is maintained by a tight hydrogen-bond between two pendant phenol/phenoxy groups of adjacent ligands and by further tight hydrogen-bonds between coordinated acetic acid molecules and the remaining pendant phenols of the ligand, generating a double acid salt of the type [CH₃COO?H?LH?L?H?OOCCH₃]⁵⁻. Reaction of H₃L with Ni(OAc)₂ and NaClO₄ in methanol gave the complex [Ni₂(HL)(OAc)₂(OH₂)₂][ClO₄]. The structure was determined by X-ray diffraction and showed that the complex exists as a dimer promoted by intermolecular hydrogen-bonding.     

Catalytic effect of cis-diammineplatinum α-pyrrolidone tan adsorbed on a platinum electrode in electrochemical oxidation of water into molecular oxygen

Cyclic voltammograms of cis-diammineplatinum α-pyrrolidone-blue and -tan, [Pt₄(NH₃)₈(C₄H₆NO)₄]ⁿ⁺ (n = 5 and 6, respectively) show for either complex only one redox peak at 0.53 V (average potential of the anodic and cathodic peak potentials). Coulometry and UVVis spectra of bulk- electrolyzed solution indicated that the redox peak corresponds to the reaction [Pt₄(NH₃)₈(C₄H₆NO)₄]⁸⁺ + 4e ⇄ 2[Pt₂(NH₃)₄(C₄H₆NO)₂]²⁺. When cyclic voltammetry is carried out in a solution of [Pt₄(NH₃)₈(C₄H₆NO)₄]⁶⁺ or a platinum electrode adsorbed with [Pt₄(NH₃)₈(C₄H₆NO)₄]⁶⁺ is used in the presence of oxidizing agent in the solution, O₂ gas generates from the electrode surface with large catalytic cathodic current at potentials below ca. 0.8 V. The O₂ gas was confirmed to generate from water by GC-MS analysis. This abnormal O₂ generation phenomenon is explained with cyclic reactions of chemical surface oxide formation on the electrode by the oxidizing agent and electrochemical reduction of the surface oxide. Oxygen gas generates from the reaction of [Pt₄(NH₃)₈(C₄H₆NO)₄]⁸⁺ or [Pt₄(NH₃)₈(C₄H₆NO)₄]⁶⁺ with OH⁻ produced in the course of the electrochemical reduction of the electrode surface oxide. The ability of [Pt₄(NH₃)₈(C₄H₆NO)₄]⁸⁺ and [Pt₄(NH₃)₈(C₄H₆NO)₄]⁶⁺ to oxidize OH⁻ into O₂ has been reported previously.     

Preparation and crystal structure of the hydroxo-bridged complex biscyclo-tri-μ-hydroxo-tris[(trans-1,2-diaminocyclohexane)platinum(II)] tris

The title compound, [C₁₈H₄₅N₆O₃Pt₃]2(SO₄)₃·14H₂O, belongs to space group C2/c, with a = 25.90(2) Å, b = 14.33(2) Å, c = 23.74(3) Å, β = 122.88(7)°, and Z = 4. The structure was refined on 2899 independent nonzero reflections to an R factor of 0.042. The crystal contains hydroxobridged cyclic [Pt₃(OH)₃(C₆H₁₄N₂)₃]³⁺ ions, in which the Pt₃O₃, ring has a chair conformation. The coordination around each Pt atom is square planar and the cyclohexyl ring lies roughly in the same plane. A large cavity between two trimeric ions related by a twofold axis is filled with one SO₄^2- ion and five water molecules, which participate in an intricate network of hydrogen bonds among themselves and with the hydroxo and amino groups of the complex cation. These units are held together in the crystal by stacking interactions between Pt(OH)₂(C₆H₁₄N₂) “planes” belonging to adjacent molecules, as well as by hydrogen bonds involving the remaining SO₄^2- ions and water molecules. The presence of the cyclohexane ring precludes λ-δ interconversion in the chelate ring and imparts rigidity to the Pt(trans-dach)²⁺ unit.     

[S2], [S3], and [N3] coordination modes of hydrotris(thioxotriazolyl)borato. Zinc, nickel, cobalt, and bismuth complexes

The ligand hydrotris(1,4-dihydro-3-methyl-4-phenyl-5-thioxo-1,2,4-triazolyl)borato (Tr^Ph,Me) was synthetized as natrium salt and the complexes [Zn(Tr^Ph,Me)₂] · 7.5H₂O · 1.5CH₃CN (2a), [Zn(Tr^Ph,Me)₂] · 8DMF (2b), [Co(Tr^Ph,Me)₂] · 8DMF (3a), [Ni(Tr^Ph,Me)₂] · H₂O · 6DMSO (4a), [Bi(Tr^Ph,Me)₂]NO₃ (5), have been isolated and structurally characterized by X-ray diffraction. In the zinc derivatives the ligand adopts different denticity and coordination modes, η² and [S₂] for 2a and η³ and [N₃] for 2b, depending on the crystallization solvent, giving rise to tetrahedral and octahedral geometry, respectively. In the octahedral cobalt and nickel complexes the ligand is η³ and [N₃] coordinated whereas in the bismuth complex the η³ and [S₃] coordination is exhibited.     

On the identification of ionic species of neutral halogen dimers, monomers and pincer type palladacycles in solution by electrospray mass and tandem mass spectrometry

Electrospray (ESI) mass spectra analysis of acetonitrile solutions of a series of neutral chloro dimers, pincer type, and monomeric palladacycles has enabled the detection of several of their derived ionic species. The monometallic cationic complexes Pd[κ¹-C,κ¹-N,κ¹-S-C(CH₃S-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]⁺ (1a) and [Pd[κ¹-C,κ¹-N,κ¹-S-C(CH₃S-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)]⁺ (1b) and the bimetallic cationic complex [κ¹-C,κ¹-N,κ¹-S-C(CH₃S-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]Pd-Cl-Pd[κ¹-C,κ¹-N,κ¹-S-C(CH₃S-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]⁺ (1c) were detected from an acetonitrile solution of the pincer palladacycles Pd[κ¹-C,κ¹-N,κ¹-S-C(CH₃S-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](Cl) 1. For the dimeric compounds {Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](μ-Cl)}₂ (2, Y=H and 3, CF₃), highly electronically unsaturated palladacycles [Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]⁺ (2d, 3d) and their mono and di-acetonitrile adducts, namely, [Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)]⁺ (2e, 3e) and [Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)₂]⁺ (2f and 3f) were detected together with the bimetallic complex [Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]-Cl-Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N](CH₃)₂]⁺ (2a, 3a) and its acetonitrile adducts [κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)Pd-Cl-Pd[ κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂]⁺ (2b, 3b) and [κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)Pd-Cl-Pd[κ¹-C, κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂(CH₃CN)]⁺ (2c, 3c). The dimeric palladacycle {Pd[κ¹-C,κ¹-N-C(CH₃O-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](μ-Cl)}₂ (4) is unique as it behaves as a pincer type compound with the OCH₃ substituent acting as an intramolecular coordinating group which prevents acetonitrile full coordination, thus forming the cationic complexes [(C₆H₄(o-CH₃O)CC(Cl)CH₂N(CH₃)₂-κO,κC,κN)Pd]⁺ (4b), [(C₆H₄(o-CH₃O)CC(Cl)CH₂N(CH₃)₂- κO,κC,κN)Pd(CH₃CN)]⁺ (4c) and [(C₆H₄ (o-MeO)CC(Cl)CH₂N(CH₃)₂-κO, κC,κN)Pd-Cl-Pd(C₆H₄(o-CH₃O)CC(Cl)CH₂N(CH₃)₂-κO,κC,κN)]⁺ (4a). ESI-MS spectra analysis of acetonitrile solutions of the monomeric palladacycles Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](Cl)(Py) (5, Y=H and 6, Y=CF₃) allows the detection of some of the same species observed in the spectra of the dimeric palladacycles, i.e., monometallic cationic 2d-3d, 2e-3e and {Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](Py)}⁺ (5a, 6a) and {Pd[κ¹-C,κ¹-N-C(Y-2-C₆H₄)C(Cl)CH₂N(CH₃)₂](CH₃CN)(Py)}⁺ (5b, 6b) and the bimetallic 2a, 3a, 2b, 3b, 2c and 3c. In all cationic complexes detected by ESI-MS, the cyclometallated moiety was intact indicating the high stability of the four or six electron anionic chelate ligands. The anionic (chloride) or neutral (pyridine) ligands are, however, easily replaced by the acetonitrile solvent.     

Hydrogen bond network structures based on sulfonated phosphine ligands: The effects of complex geometry, cation substituents and phosphine oxidation on guanidinium sulfonate sheet formation

Interactions between guanidinium cations and the sulfonate groups on the phosphine [PPh₂C₆H₄-m-SO₃]⁻ have been exploited to incorporate iridium(I) centres into hydrogen-bonded networks. The crystal structure of [C(NH₂)₃]₂{trans-[IrCl(CO)(PPh₂C₆H₄-m-SO₃)₂]} (4) contains hexagonal guanidinium sulfonate (GS) sheets in which both of the sulfonate groups from each complex anion form hydrogen bonds within the same sheet. The crystal structures of [C(NH₂)₂(NHMe)][PPh₂C₆H₄-m-SO₃] (5) and [C(NH₂)₂(NHEt)][PPh₂C₆H₄-m-SO₃] (6) reveal that the GS sheets can tolerate the loss of one hydrogen bond donor, though twisting occurs to accommodate the alkyl group. However, the crystal structure of [C(NH₂)₂(NMe₂)][PPh₂C₆H₄-m-SO₃] (7) shows that ribbon structures are formed instead of sheets when two hydrogen bond donors are lost. The compound [C(NH₂)₂(NHMe)]₂{trans-[IrCl(CO)(PPh₂C₆H₄-m-SO₃)₂]} · 3/8H₂O (8) contains hydrogen-bonded cylinders as opposed to sheets. This is a likely consequence of a mismatch between the intramolecular S?S distance present in the anion, and the closer S?S distance present in a twisted GS sheet such as that in 5. The crystal structures of [C(NH₂)₂(NHEt)][P(O)Ph₂C₆H₄-m-SO₃] (9) and [C(NH₂)₂(NMe₂)][P(O)Ph₂C₆H₄-m-SO₃] · H₂O (10) show that the phosphine oxide group successfully competes with the sulfonate as a hydrogen bond acceptor. The crystal structure of 9 contains hydrogen-bonded ribbons that are interlinked through the anions which act as pillars to form a layer structure. In contrast, the crystal structure of 10 contains hydrogen-bonded sheets that involve cations, sulfonate groups, phosphine oxides and the included water molecule. These sheets are linked into a three-dimensional network through the anion pillars.     

Synthesis and structural characterisation of new cationic dinuclear ruthenium(II) thiolato complexes of the type [Ru2(η-arene)2(μ-p-S-C6H4-Br)3]

Dinuclear dichloro complexes [Ru(C₆H₆)Cl₂]₂, [Ru(p-MeC₆H₄ ⁱPr)Cl₂]₂, [Ru(1,2,4,5-C₆H₂Me₄)Cl₂]₂, and [Ru(C₆Me₆)Cl₂]₂ react in ethanol with p-bromothiophenol to give the corresponding cationic complexes [Ru₂(C₆H₆)₂(p-S-C₆H₄-Br)₃]⁺ (1), [Ru₂(p-MeC₆H₄ ⁱPr)₂(p-S-C₆H₄-Br)₃]⁺ (2), [Ru₂(1,2,4,5-C₆H₂Me₄)₂(p-S-C₆H₄-Br)₃]⁺ (3), and [Ru₂(C₆Me₆)₂(p-S-C₆H₄-Br)₃]⁺ (4), which can be isolated in quantitative yield as their chloride salts. X-ray structure analysis of these complexes shows that the nature of the arene ligand influences the folding of the p-S-C₆H₄-Br units. In 1, where the less hindered arene ligand is present, the three phenyl rings of the thiolato units are not constrained to a coplanar arrangement, whereas in 4 the C₆Me₆ forces the three phenyl rings to be in perfect planarity. Complexes 2 and 3 show an intermediary arrangement.     

Cobalt and nickel complexes of versatile imidazole- and pyrrole-2-carbaldehyde thiosemicarbazones. Synthesis, characterisation and antimicrobial activity

Ni(II), Co(II) and Co(III) complexes of imidazole- and pyrrole-2-carbaldehyde thiosemicarbazone ligands (H₂L¹ and H₂L², respectively) have been prepared. The X-ray crystal structures of [Co(L¹)(HL¹)], [Ni(H₂L¹)₂]Cl₂ · 3.5H₂O and [Ni(HL²)₂] have been solved. The Co(III) ion assumes a slightly distorted octahedral coordination geometry, involving both N₂S binding domain of di- and monoanionic ligand molecules. Whereas in [Ni(HL²)₂] the metal ion is tetracoordinated in a square planar geometry by two pyrrole-2-carbaldehyde thiosemicarbazone molecules acting as NS-donor, the spatial array of non deprotonated H₂L¹ ligand molecules in [Ni(H₂L¹)₂]Cl₂ · 3.5H₂O is equivalent to that found for [Co(L¹)(HL¹)]. The in vitro antimicrobial properties of the ligands and their complexes were tested against representative bacterial and fungal strains in broth culture. The compounds H₂L² and [Co(L²)(HL²)(H₂L²)] · 1.5H₂O exhibit a moderate inhibitory effect on the microbial proliferation and only against some Gram positive bacteria.     

Electrochemical behavior of S,S-bridged adducts of square planar metalladithiolene complexes [M(S2C2Ph2)2](M=Ni, Pd, and Pt)

The electrochemical behavior of the S,S^′-bridged adducts of square planar metalladithiolene complexes was investigated by using cyclic voltammetry and electrochemical spectroscopies (visible, near-IR, and ESR). The norbornene-bridged S,S^′-adduct [Ni(S₂C₂Ph₂)₂(C₇H₈)] (2a; C₇H₈=norbornene) formed by [Ni(S₂C₂Ph₂)₂] (1a) and quadricyclane (Q) was dissociated by an electrochemical reduction, and anion 1a⁻ and norbornadiene (NBD) were formed. Q was isomerized to NBD in the overall reaction. The o-xylyl-bridged S,S^′-adduct [Ni(S₂C₂Ph₂)₂(CH₂)₂(C₆H₄)] (3a; (CH₂)₂(C₆H₄)=o-xylyl) was also dissociated by an electrochemical reduction, and this reaction gave the o-xylyl radical (o-quinodimethane). The reduction of complex 3a in the presence of excess o-xylylene dibromide underwent the catalytic formation of o-quinodimethane. The butylene-bridged S,S^′-adduct [Ni(S₂C₂Ph₂)₂(CH₂)₄] (4a; (CH₂)₄=butylene) was stable on an electrochemical reduction. The lifetimes of reduced species of these adducts 2a-4a were influenced by the stability of the eliminated group (stability: NBD > o-xylyl radical (o-quinodimethane) > butylene radical). Therefore, the reduced species are stable in the sequence 4a⁻ > 3a⁻ > 2a⁻. Although the palladium complex [Pd(S₂C₂Ph₂)₂] (1b) was easier to reduce than the nickel complex 1a or the platinum complex [Pt(S₂C₂Ph₂)₂] (1c), their S,S^′-adducts were easier to reduce in the order of Ni adduct > Pd adduct > Pt adduct.     

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.     

Novel supramolecular compounds based on Cucurbit[6]uril, 1,8-diaminooctane and octahedral thiohydroxo anions with cluster core [Re6S8]

Supramolecular compounds {C₈N₂H₂₂@Cuc[6]}{Re₆S₈(H₂O)₂(OH)₄}·18H₂O (1), and K₂{C₈N₂H₂₂@Cuc[6]}{Re₆S₈(OH)₆}·14H₂O (2) were obtained by crystallization from aqueous solutions that contained the macrocyclic cavitand cucurbit[6]uril (C₃₆H₃₆N₂₄O₁₂), 1,8-diaminooctane and the cluster thiohydroxo complex [Re₆S₈(OH)₆]⁴⁻. The resultant composition of the formed compounds depends on the experiment technique. According to the X-ray diffraction analysis, 1,8-diaminooctane molecules are encapsulated within the cavity of the cucurbit[6]uril molecules in such a way that the aminogroups are above and below the plane of the cavitand. The 1,8-diaminooctane molecules formed hydrogen bonds with the cavitand and the cluster thiohydroxo complexes to give chains.