Koordination von Rhodium(III), Iridium(III) und Kupfer(II) mit dem potentiell vierzähnigen Akzeptorliganden Bis(1‐methylimidazol‐2‐yl)glyoxal (big)

Coordination of Rhodium(III), Iridium(III), and Copper(II) with the Potentially Tetradentate Acceptor Ligand Bis(1‐methylimidazol‐2‐yl)glyoxal (big) Bis(1‐methylimidazol‐2‐yl)glyoxal (big) which has hitherto not been used in coordination chemistry crystallizes to form two perpendicular 1‐methylimidazol‐2‐yl‐carbonyl molecular halves. Out of the various possibilities for mono‐ and bis‐chelate coordination the N,N′‐alternative with a seven‐membered chelate ring is realized in [Cp*Cl(big)Rh](PF₆) as evident from crystal structure analysis. The iridium analogue reacts under hydration of big and elimination of HCl to form a complex cation [Cp*(bigOH)Ir]⁺ which dimerizes in the crystal through hydrogen bonding and contains one five‐ and one six‐membered chelate ring involving the alcoholate‐O. Cu(ClO₄)₂ and the ligand big yield a complex ion [Cu(big)₂]²⁺ with an ESR spectrum that suggests the coordination of the central metal by four N atoms in an approximately planar setting.     

DFT study of bis(picolinato-N,O)-copper(II) complex

The geometry of bis(pyridine-2-carboxylato-N,O)-copper(II) complex is optimized at B3LYP/6-311G^∗ level of theory and compared with experimental data. Comparing the electronic structure of this complex with that of its anionic ligand does not indicate any mechanical strain in the five-membered Cu–O–C–C–N metallocycle. The copper d-electron population of 9.2 corresponds to Cu(II) oxidation state. Using 6-31G^∗ basis sets produces an incorrect non-planar structure of the complex.     

Dehydrotropylium-Co2(CO)6 ion: generation, reactivity and evaluation of cation stability

The dehydrotropylium–Co₂(CO)₆ ion was generated by the action of HBF₄ or BF₃ ? OEt₂ on the corresponding cycloheptadienynol complex, which in turn has been prepared in four steps from a known diacetoxycycloheptenyne complex. The reaction of the cycloheptadienynol complex via the dehydrotropylium–Co₂(CO)₆ ion with several nucleophiles results in substitution reactions with reactive nucleophiles (N>1) under normal conditions, and a radical dimerisation reaction in the presence of less reactive nucleophiles. Competitive reactions of the cycloheptadienynol complex with an acyclic trienynol complex show no preference for generation of the dehydrotropylium–Co₂(CO)₆ ion over an acyclic cation. DFT studies on the dehydrotropylium–Co₂(CO)₆ ion, specifically evaluation of its harmonic oscillator model of aromaticity (HOMA) value (+0.95), its homodesmotic‐reaction‐based stabilisation energy (≈2.8 kcal mol^?1) and its NICS(1) value (?2.9), taken together with the experimental studies suggest that the dehydrotropylium–Co₂(CO)₆ ion is weakly aromatic.     

Synthesis,crystal structure,and properties of copper(II) and manganese(II) complexes with azide and 3,4-di(2′-pyridyl)-1,2,5-oxadiazole

Two transition metal complexes with azide and 3,4-di(2′-pyridyl)-1,2,5-oxadiazole (dpo), [Cu₂(dpo)₂(N₃)₄] (1), and [Mn(dpo)₂(N₃)₂] (2), have been synthesized and characterized by single-crystal X-ray diffraction. The Cu(II) complex is binuclear with double end-on (EO) azido bridges, in which each Cu(II) ion assumes a distorted square pyramidal geometry, and each EO azido bridge adopts a quasi-symmetric fashion. In contrast, the Mn(II) complex is mononuclear, in which the Mn(II) ion is ligated by two dpo ligands and two terminal azide ions, with a distorted octahedron geometry. Magnetic studies on the Cu(II) complex revealed that the double EO azido bridge mediates ferromagnetic coupling with J=12.8 cm⁻¹.     

Bis[N,N'-diisopropylbenzamidinato(-)]silicon(II): a silicon(II) compound with both a bidentate and a monodentate amidinato ligand

Well looked-after: reductive HCl elimination of the λ(6)-silicon(IV) complex 1 leads to the λ(3)-silicon(II) species 2, a novel type of donor-stabilized silylene. Reaction of 2 with [W(CO)(6)] and with I(2) yields the λ(5)-silicon(II) complex 3 and the λ(6)-silicon(IV) complex 4, respectively.     

Preparation of enol ethers by carbonyl olefination utilizing an alkoxymethyl chloride-titanocene(II) system

Aldehydes, ketones, esters and lactones are transformed into enol ethers or 1,2-dialkoxy-1-alkenes by treatment with organotitanium species prepared from alkoxymethyl chlorides and a titanocene(II) complex.     

Hydrosilylation of alkynes by Ni(CO)3-stabilized silicon(II) hydride

Not copy and paste: Although β-diketiminato ligands have been employed for the stabilization of Ge(II) and Sn(II) hydrides, the corresponding Si(II) hydride is not accessible. However, coordination of silicon(II) to a {Ni(CO)(3)} fragment allowed the isolation of the first Si(II) hydride metal complex 1. This complex was used for the first silicon(II)-based and Ni(0)-mediated, stereoselective hydrosilylation of alkynes. R = phenyl, tolyl.     

Die Kristallstruktur von Tetraphenylarsonium-tetrabromooxotechnetat(V), (Ph4As)TcOBr4

The Crystal Structure of Tetraphenylarsonium-tetrabromooxotechnetate(V), (Ph₄As)TcOBr₄ (Ph₄As)TcOBr₄ has been prepared from (Bu₄N)TcO₄, HBr and (Ph₄As)Br. The crystal structure of the complex has been determined by X-ray diffraction using MoKα radiation. The crystals are tetragonal, space group P 4/n with a = 1276.6(1) pm, c = 803.2(1) pm, Z = 2. The refinement based on 1595 reflexes converged to R = 0.034. The structure consists of discrete TcOBr₄^? anions and Ph₄As⁺ cations. The technetium is coordinated in a square pyramidal environment. A C_4v symmetry was derived for the complex anion. With this, it is isomorphous to the other structurally studied (Ph₄As)TcYX₄ complexes (Y = O, N; X = Cl, Br). The Tc = O length is 161.3(9) pm with Tc? Br 246.0(1) pm     

Bis(calixcrown)tetrathiafulvalene receptors

A new class of electroactive receptors has been synthesized, built by covalent association of five subunits: two calixarene platforms for spatial organization, two polyether 3D cavities for cation binding, and one electroactive TTF unit to probe the complexation event. Sodium complexation induces rigidification of the molecular assembly, as shown by 1H NMR titration and single-crystal X-ray crystallographic studies on free receptor 14 and a corresponding complex with two bound sodium atoms per receptor (15-(NaPF6)2). The calixarene units in these receptors change from a pinched cone conformation in the free ligand to a symmetrical cone in the complex. Cyclovoltammetric studies validated the electrochemical recognition concept of these five-member assemblies.     

Ligand‐Supported Facile Conversion of Uranyl(VI) into Uranium(IV) in Organic and Aqueous Media

Reduction of uranyl(VI) to U^V and to U^IV is important in uranium environmental migration and remediation processes. The anaerobic reduction of a uranyl U^VI complex supported by a picolinate ligand in both organic and aqueous media is presented. The [U^VIO₂(dpaea)] complex is readily converted into the cis‐boroxide U^IV species via diborane‐mediated reductive functionalization in organic media. Remarkably, in aqueous media the uranyl(VI) complex is rapidly converted, by Na₂S₂O₄, a reductant relevant for chemical remediation processes, into the stable uranyl(V) analogue, which is then slowly reduced to yield a water‐insoluble trinuclear U^IV oxo‐hydroxo cluster. This report provides the first example of direct conversion of a uranyl(VI) compound into a well‐defined molecular U^IV species in aqueous conditions.     

Bis(triphenylphosphin)iminium-bis(methoxo)phthalocyaninato(2–)ferrat(III) – Synthese und Kristallstruktur

Bis(triphenylphosphine)iminium Bis(methoxo)phthalocyaninato(2–)ferrate(III) – Synthesis and Crystal Structure Chlorophthalocyaninato(2–)ferrate(III) reacts with bis(triphenylphosphine)iminium hydroxide in methanol/acetone solution to yield blue crystals of bis(triphenylphosphine)iminium bis(methoxo)phthalocyaninato(2–)ferrate(III). The complex salt crystallizes as an acetone/methanol solvate (^bPNP)[Fe(OCH₃)₂pc^2–] · (CH₃)₂CO · 1.5 CH₃OH in the triclinic space group P 1 (no. 2) with the cell parameters a = 13.160(5) Å, b = 15.480(5) Å, c = 17.140(5) Å, α = 97.54(5)°, β = 91.79(5)°, γ = 95.44(5)°. The Fe atom is located in the centre of the pc^2– ligand coordinating four isoindole N atoms (N_iso) of the pc^2– ligand and two O atoms of the methoxo ligands in a mutual trans arrangement. The average Fe–O and Fe–N_iso distances are 1.887 and 1.943 Å, respectively. The cation adopts the bent conformation (< P–N–P = 140.4(2)°) with P–N distances of 1.579(3) and 1.575(3) Å.     

配合物(enH_2)_(0.5)[Zn(en)_3](SCN)_3单晶生长与表征(英文)

以NH4SCN,ZnCl2,乙二胺和盐酸为反应原料,采用缓慢降温法,从水溶液中生长了尺寸为11×6×3mm3新的化合物(enH2)0.5[Zn(en)3](SCN)3单晶体;采用元素分析、红外光谱、EDS、TG/DTA、粉末X射线衍射和单晶X射线衍射等手段对所生长的晶体进行了表征,结果发现,所生长的晶体分子式为:(enH2)0.5[Zn(en)3](SCN)3,属于三角晶系P-3c1空间群,晶胞参数为:a=12.0355(17),b=12.0355(17),c=17.086(3),V=2143.4(6)3,Z=4。热分析结果表明,晶体在温度达135℃具有良好的物理化学稳定性并且热分解的最终残留物是ZnS。采用重量法,化合物(enH2)0.5[Zn(en)3](SCN)3在不同温度条件下的溶解度也已测定。荧光分析表明,该固体配合物在蓝光区表现出强的蓝色发光量子效应。采用维氏显微硬度法对该晶体的力学性能进行了研究,其硬度值为56.6kg/mm2。CCDC:767781     

A photoswitchable Zn (II) selective spiropyran-based sensor

A spiropyran-based fluorescent and photoregenerable receptor, that is, selective towards zinc(II) ions over a series of biologically and environmentally relevant cations has been designed and synthesized. The complex formation gives rise to colour changes that are visible to the naked eye and reversible upon visible light irradiation. ¹H NMR studies confirm that the closed form is converted to the open trans-merocyanine complex upon addition of zinc ions.     

Intercalation of molybdenum disulfide with chlorobis(phenanthroline)copper(II)

An intercalation compound of molybdenum disulfide with the copper complex Cu^II(phen)₂Cl⁺ was found to form by the interaction of the MoS₂ single-layer dispersions with the complex and by the treatment of the phenanthroline intercalation compound with CuCl₂. The compositions and structures of the compounds formed were determined by powder diffractometry and electron microscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2648–2654, December, 2005.     

The use of 3,3-bis(2-imidazolyl) propionic acid (bip-OH) as a new chelating ligand for Re(CO)3 and Ru complexes: Formation of organometallic PNA oligomers with (bip)Re(CO)3 and their interaction with complementary DNA

We report the use of 3,3-bis(2-imidazolyl) propionic acid (bip-OH, 1) as a new chelating bis(imidazole) ligand. The synthesis and full characterization of complexes Re(bip-O)(CO)₃2 and [Ru(bpy)₂(bip-OH)]²⁺3 is reported. Both complexes show interesting spectroscopic properties, namely IR for compound 2 and ¹H NMR for 3, respectively. The free carboxylic acid functionality of 1 may be used for the coupling to biomolecules. We have prepared two peptide nucleic acid (PNA) decamers to which the rhenium complex 2 is coupled. All reactions were carried out by solid phase synthesis methods. The Re-PNA oligomer conjugates Re(CO)₃(bip- tgt cta gca a -NH₂) 4 and Re(CO)₃(bip- agg agc aac t-Lys-NH₂) 5 were obtained in good yield and high purity after HPLC purification and identified by their mass spectra. The interaction of 5 with complementary DNA yields a melting temperature of (53.9 ± 1) °C. This is the first DNA melting temperature reported for an organometallic metal-PNA conjugate.     

Spiroconjugation in spirodicorrolato-dinickel(II)

In the present work the effect of spiroconjugation on the electronic spectrum of the recently synthesized metal complex hexadecaethylspirodicorrolato-dinickel(II) (5) (the corrole units in 5 are isoforms) is investigated. To have a suitable reference compound at our disposal, tetraethylhexamethylisocorrolato nickel(II) (7) has been prepared. On comparing the electronic spectra of this reference compound and the spiro-complex, bathochromic shifts of all absorption bands in the NIR/Vis-region are observed for the latter as well as marked changes in the spectral intensities. A detailed analysis of the spectra supported by semiempirical calculations reveals that at least part of the observed changes can be unambiguously attributed to the spiro effect. This effect is further affirmed by electrochemically measured redox potentials.     

Darstellung und Charakterisierung von [N-(2-Mercaptoacetyl)-N′ -4-(penten-3on-2)ethylen-1,2-diaminato]oxorhenium(V), ReO(MRP 40)

Synthesis and Characterization of [N-(2-Mercaptoacetyl)-N′ -4-(penten-3on-2)ethylen-1,2-diaminato]oxorhenium(V), ReO(MRP 40) The title complex is obtained in good yields from the reaction of the triphenylmethyl-protected ligand with (Bu₄N)ReOBr₄ or ReOCl₃(Ph₃P)₂. The structure of the compound as neutral oxorhenium(V) complex is confirmed by analytical, ¹H-, ¹³C-NMR, IR, UV/Vis as well as mass spectrometric studies.     

Evaluation of the Antiviral Activity against Infectious Pancreatic Necrosis Virus (IPNV) of a Copper (I) Homoleptic Complex with a Coumarin as Ligand

The aquatic infectious pancreatic necrosis virus (IPNV) causes a severe disease in farmed salmonid fish that generates great economic losses in the aquaculture industry. In the search for new tools to control the disease, in this paper we show the results obtained from the evaluation of the antiviral effect of [Cu(NN₁)₂](ClO₄) Cu(I) complex, synthesized in our laboratory, where the NN₁ ligand is a synthetic derivate of the natural compound coumarin. This complex demonstrated antiviral activity against IPNV at 5.0 and 15.0 µg/mL causing a decrease viral load 99.0% and 99.5%, respectively. The Molecular Docking studies carried out showed that the copper complex would interact with the VP2 protein, specifically in the S domain, altering the process of entry of the virus into the host cell.     

Infrared Spectroscopic and Gravimetric Studies on the Dicyclohexylaminecadmium(II) Tetracyanopalladate(II) Host-Aromatic Guest Systems

The host complex Cd(Cyclohexylamine)₂Pd(CN)₄ has been prepared in powder form. The spectral data suggest that the structure of this complex issimilar to those of the Hofmann-dma-type hosts. The sorption processes of thearomatic guests (benzene, toluene,o-, m-, p-xylene, naphthalene, 1,2-, 1,3-, 1,4-dichlorobenzene and 1,4-dibromobenzene) in this host have been examined at room temperature by gravimetric and spectroscopic measurements.The desorption of the benzene guest against time has been measured. The hoststructure changes on inclusion of the guests and recovers after liberations. Thehost complex has been suggested as sorbents for selective absorption.     

Synthese und Struktur der Platin(O)-Verbindungen [(dipb)Pt]2(COD) und (dipb)3Pt2 sowie des clusters Hg6[Pt(dipb)]4 (dipb = (i-Pr)2P(CH2)4P(i-Pr)2)

Synthesis and Structure of the Platinum(0) Compounds [(dipb)Pt]₂(COD) and (dipb)₃Pt₂ and of the Cluster Hg₆[Pt(dipb)]₄ (dipb = (i-Pr)₂P(CH₂)₄P(i-Pr)₂) The reduction of (dipb)PtCl₂ with Na/Hg yields (dipb)Pt as an intermediate which reacts with the amalgam to form the cluster Hg₆[Pt(dipb)]₄ ( 3 ) or decomposes to (dipb)₃Pt₂ ( 2 ) and Pt. In the presence of COD [(dipb)Pt]₂(COD) ( 1 ) is obtained. 1 crystallizes monoclinicly in the space group P2₁/c with a = 1596.1(4), b = 996.5(2), c = 1550.4(3) pm, β = 113.65(2)°, Z = 2. In the dinuclear complex two (dipb)Pt units are bridged by a 1,2-η²-5,6-η² bonded COD ligand. Whereby the C = C double bonds are lengthened to 145 pm. 2 forms triclinic crystals with the space group P1 and a = 1002.0(2), b = 1635.9(3), c = 868.2(2) pm, α = 94.70(2)°, β = 94.45(2)°, σ = 87.95(1)°, Z = 1. In 2 two (dipb)Pt moieties are connected by a μ-dipb ligand in a centrosymmetrical arrangement. 3 is monoclinic with the space group C2/c and a = 1273.8(3), b = 4869.2(6), c = 1660.2(3) pm, β = 95.16(2)°, Z = 4. The clusters Hg₆[Pt(dipb)]₄ have the symmetry C₂. Central unit is a Hg₆ octahedron of which four faces are occupied by Pt(dipb) groups. The bonding in the cluster is discussed on the basis of eight Pt? Hg two center bonds of 267.6 pm and two Pt? Hg? Pt three center bonds with Pt? Hg = 288.0 pm.