Dowex Polymer–Mediated Protection of Carbonyl Groups

Dowex (strongly acidic cationic exchange resin) polymer is employed as solid acid catalyst for the clean and less hazardous protection of carbonyl compounds as phenylhydrazones and 2,4‐dintrophenylhydrazones in ethanol under reflux conditions. The reactions proceed very smoothly and the yields of the derivatives are excellent.     

Experimental and Simulation Research of Spatial Distribution of Carbonyl Groups in γ-Irradiated Polyethylene

The dependence of the optical density in the peak of the characteristic IR absorption band of carbonyl groups on the thickness of polyethylene films irradiated with 60Co gamma quanta is experimentally determined. A method for calculating the distribution of CO groups relative to the frontal surfaces of the samples is proposed and justified. The calculated curves are discussed in terms of the generally accepted model of diffusion-controlled oxidation of polymers under the action of high energy radiation. Based on the data obtained, the conditions for the radiation modification of polymers are found, which make it possible to minimize the destructive effects of oxidation.     

Synthesis and Structure of New Cobalt–Carbonyl Complexes Containing Tellurium Atoms

Co₂(CO)₈ and Te₂O react to form the well known Co₄(CO)₁₀Te₂, Co₄(CO)₁₁Te₂ complexes and the two new cluster complexes CCo₆(CO)₁₂Te₂(1), and CCo₆(CO)₁₀Te₂(Te₃) (2). The structures of 1 and 2 were determined by X-ray analysis, together with the triphenylphosphine derivative of 1, CCo₆(CO)₁₁(PPh₃)Te₂(3), which was analyzed to clarify the disordered structure of the parent compound. Complex 1 is formed by a prismatic cluster of cobalt atoms with a carbon embedded in the cage; two tellurium atoms cap the triangular faces of the prism and each cobalt atom links two terminal carbonyl groups. The complex 2 has a similar prismatic cage CCo₆; two ₄-Te atoms cap two rectangular faces of the prism, while other two Te atoms bridge two edges of the triangular faces and are linked each other through a third Te atom. Electron counting gives for complex 2 92 electrons: the presence of two long Co–Co distances suggests that the two excess electrons are located on Co–Co antibonding orbitals. Crystal data for 1, space group C2/c, a = 12.845(2) Å, b = 13.449(2) Å, c = 13.246(2) Å, = 91.95(2)°, Z = 4, R = 0.097 for 2555 reflections; for 2, space group Pnna, a = 17.219(5) Å, b= 14.969(6) Å, c = 9.178(4) Å, Z = 4,R = 0.037 for 3103 reflections; for 3, space group P2₁/c, a = 9.288(2) Å, b = 14.920(6) Å, c = 26.300(9) Å, = 99.99(2)°, Z = 4, R = 0.037 for 4300 reflections. The vibrational analysis of the complex 1 was performed and most of the (CO), (₆C–Co), (Co–Co) and (Co–Co) modes were assigned. The (Co–Te) modes were interpreted on the basis of the intermolecular coupling, due to the close contact between neighboring clusters in one distinct direction in the crystal.     

Observation of CH⋅⋅⋅π Interactions between Methyl and Carbonyl Groups in Proteins

Protein structure and function is dependent on myriad noncovalent interactions. Direct detection and characterization of these weak interactions in large biomolecules, such as proteins, is experimentally challenging. Herein, we report the first observation and measurement of long-range “through-space” scalar couplings between methyl and backbone carbonyl groups in proteins. These J couplings are indicative of the presence of noncovalent C−H⋅⋅⋅π hydrogen-bond-like interactions involving the amide π network. Experimentally detected scalar couplings were corroborated by a natural bond orbital analysis, which revealed the orbital nature of the interaction and the origins of the through-space J couplings. The experimental observation of this type of CH⋅⋅⋅π interaction adds a new dimension to the study of protein structure, function, and dynamics by NMR spectroscopy.     

Metal- and Additive-Free Electrochemical Oxidation of Benzylic C−X Bonds to Carbonyl Groups

A scalable electrochemical strategy for oxidation of various benzylic C−X bonds to carbonyl groups was achieved. The protocol runs under mild reaction conditions and air atmosphere in a simple undivided electrolysis cell, H₂O as oxygen source, and cheap graphite plates as both anode and cathode. In addition, the electrolysis strategy features good functional groups tolerance for selectively generating structure versatile ketones, aldehydes, and esters.     

Synthesis and Structure of Binary Complexes of Platinum Group Metals — Precursors of Metallic Materials

This paper reviews the results of structural studies of binary complexes whose cationic part contains cobalt, rhodium, iridium, ruthenium, and chromium chloropentammne. The structure of these compounds is discussed in the light of the design of new multicomponent precursor compounds. Data are given on the chemical and phase compositions of the polymetallic powders resulting from the thermal decomposition of the compounds studied.     

Syntheses and Characterization of Pentacoordinate Organotin (Ⅳ) Complexes

Ten novel pentacoordinate organo-tin complexes were prepared and characterized. Singlecrystal structure determination by X-diffraction was made.     

Syntheses,Characterization and Crystal Structures of Dithiocarbamate-based Mononuclear Palladium(Ⅱ) Complexes

By employing the dithiocarbamate salt(K(PPDC), where PPDC = 4?-pyridyl-1-piperazine-4-dithiocarbamate) as the functional ligand and di-palladium complexes [(N^N)_2Pd_2(NO_3ˉ)_2](NO3ˉ)2(N^N = 2,2?-bipyridine, bpy; 4,4?-dimethylbipyridine, dmbpy) as corner, two novel single metal complexes with Pd(II) centers have been obtained. These organic-metal complexes were characterized by NMR, ESI-MS, elemental analysis, Uv-vis spectra and single-crystal X-ray diffraction analysis. Compound 1·(PF6)2([(bpy)Pd(PPDC)]·(PF6)2) crystallizes in triclinic, space group P1, a = 8.3968(5), b = 11.5565(7), c = 18.2234(11) ?, α = 97.505(1), β = 91.424(1), γ = 106.146(1)o, C22H24N6S2P2F12 Pd, Mr = 832.93, V = 1680.58(18) ?~3, Z = 2, Dc = 1.646 Mg/m3, μ(MoK α) = 0.863 mm-1, F(000) = 828, the final R = 0.0455 and wR = 0.1390 for 6981 observed reflections with I 2σ(I). Similarly, compound 2·(PF6)2([(dmbpy)Pd(PPDC)]·(PF6)2) also crystallizes in triclinic, space group P1, a = 13.9467(3), b = 14.8390(2), c = 17.0632(3) ?, α = 81.8680(10), β = 87.051(2), γ = 83.4590(10)o, C_(22)H_(25)N_5S_2P_2F_(12)Pd, M_r = 819.93, V = 3470.81(11) ?~3, Z = 4, D_c = 1.569 Mg/m~3, μ(CuK α) = 7.115 mm~(-1), F(000) = 1632, the final R = 0.0606 and w R = 0.1637 for 12835 observed reflections with I 2σ(I). Crystallography reveals that each metal center coordinates with two N atoms from bpy and two S atoms from PPDC in the square coordination mode. In the crystal structure of complex 1, a weak Pd···Pd interaction can be observed. Interestingly, it was also found that the mononuclear moieties of complex 2 could be packed into a 3-D porous framework via multiple intermolecular C–F···H hydrogen-boding interactions which extended in the a, b, and c axes with PF_6ˉ anions frozen inside.     

Nonheme Oxovanadium(Ⅴ,Ⅳ) Complexes Catalyze the Oxidative Cleavage of Catechols

Introductionlnrecentyearstherehasbeenanincreasinginterestinthebiochemisto'ofnonhemeenZymeslnvoIvedindioxygenactivation1Theactivesiteofintradiol-cleavingcatecholdioxygenasescomprisesanonhemeiron(III).Theenn'mecatal}'zestheoxjdatjvec1eavageoftheintradiol-C-Cbondofvariouscatecholderivativeswithmolecularoxygen.}'ieldingthecorrespondingmuconicacid.Probablythemostunusualpropem'ofthisenp'meisthatthetri\'alentoxidationstateoftheironcenterisretainedthrouRhoutthecatalVticc.cle.2Thediversityofbiologi…     

Crystallographic and Theoretical Evidences of Anion⋅⋅⋅Anion Interaction

Planar (HgCl₃)⁻ anions are stacked fairly closely together in a slipped parallel arrangement within several crystal structures. Quantum chemical analysis shows evidence of strong noncovalent spodium bonds between the Hg π-hole of one unit and the Cl atom of an adjacent unit. Anion⋅⋅⋅anion spodium bonds work in tandem with crystal packing forces.     

Synthesis,Structure, and Haptotropic Interconversions of Tungsten Cycloheptatrienyl–Acetonitrile–Carbonyl Complexes

Russian Journal of Coordination Chemistry - Tungsten cycloheptatrienyl complexes (η7-C7H7)W(CO)2I (I), [(η3-C7H7)W(CO)2(CH3CN)3]PF6 (II), and [(η7-C7H7)W(CO)2(CH3CN)]PF6 (III) (CIF...     

Functionalized Trifluoromethyl-Containing Lithium β-Diketonate in the Synthesis of Homo- and Heteronuclear Complexes of Rare-Earth Metals

Russian Journal of Coordination Chemistry - The reactions of functionalized lithium CF3-β-diketonate (LiL) with trivalent rare-earth metal salts in methanol afford homobinuclear and...     

Synthesis and Characterization of Two Binuclear Macrocyclic Zinc(Ⅱ) Complexes by Anion Exchange

Two macrocyclic zinc(II) complexes {[ZnL(VO3)2]·0.33H2O}n(1) and [ZnL(H2O)2][Ni(CN)4](2)(L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) have been obtained from the reactions of [ZnL](ClO4)2 with NH4VO3 and K2[Ni(CN)4], respectively, and structurally characterized by elemental analysis, IR, XRPD, TG and X-ray diffraction. Single-crystal X-ray diffraction analyses indicated that the Zn(II) atom lies on an inversion center and is octahedrally coordinated by four nitrogen atoms of the tetradentate macrocyclic ligand in the equatorial plane and two oxygen atoms of [VO4] tetrahedra in the axial positions in 1, and two oxygen atoms of two water molecules in 2. Complex 1 shows a three-dimensional structure, which is constructed by the links of [VO3]nn- chains with [ZnL]2+, forming one-dimensional channels occupied by guest water molecules. The monomers of [ZnL(H2O)2]2+ and [Ni(CN)4]2- are connected through the intermolecular hydrogen bonds to form a two-dimensional sheet in complex 2.     

Silica-supported Polysiloxanes with Dithiacrown Ether Groups and Their Platinum Complexes

The present paper represents the syntheses of polypropyloxymethyldithia 15-crown-5 and 18-crown-6 supported on silica and their platinum complexes. The platinum complexes are effective catalysts for the hydrosilylation of olefins with triethoxysilane. The influences of temperature, amount of platinum complexes used and the nature of olefins used on the catalytic activity of the complexes are also investigated in this paper.     

Molecular Recognition of Bases and Nucleosides by Mono－substituted Mononuclear Complexes of 1,4,7,10－Tetraaza－cyclododecane

The mononuclear macrocyclic polyamine metal complexes 5a-5e have been shown to form stable 1 : 1 complexes with bases and nucleosides. Their binding constants (K) were determined by UV-visible spectrometric titration. The results show that recognition ability of the complexes 5a--5e for uracil, U (Uridine), dT (Thymidine) is higher than that for the other bases or nucleosides (such as Cytidine, Guanosine, Adenosine). The metal ion also plays an important role for the recognition ability of complexes.     

Impact of Group 10 Metals on the Solvent-Induced Disproportionation of o-Semiquinonato Complexes

The oxidation of [M^II(3,5-DTBCat)(DTBbpy)] (M=Ni ( [Ni] ), Pd ( [Pd] ), and Pt ( [Pt] ); 3,5-DTBCat=3,5-di-tert-butylcatecholato; DTBbpy=4,4′-di-tert-butyl-2,2′-bipyridine) afforded the dimeric {[Ni^II(3,5-DTBSQ)(DTBbpy)](PF₆)}₂ ( {[Ni](PF₆)}₂ ; 3,5-DTBSQ=3,5-di-tert-butylsemiquinonato) and monomeric semiquinonato (SQ) complexes [M^II(3,5-DTBSQ)(DTBbpy)](PF₆) (M=Pd ( [Pd](PF₆) ) and Pt ( [Pt](PF₆) )). The negative solvatochromic properties of the SQ complexes allowed us to estimate the relative order of their dipole moments: [Pd](PF₆) > [Pt](PF₆) > {[Ni](PF₆)}₂ . The complexes [Pd](PF₆) and [Pt](PF₆) adopt monomeric structures and are stable in CH₂Cl₂ and toluene, whereas they gradually disproportionate at room temperature to [M] and 3,5-di-tert-butylbenzoquinone (3,5-DTBBQ) in polar solvents such as THF, MeOH, EtOH, DMF, or DMSO. The results of spectroscopic studies suggested that the oxidized nickel complex adopts a monomeric structure ( [Ni](PF₆) ) in CH₂Cl₂, but a dimeric structure ( {[Ni](PF₆)}₂ ) in the other investigated solvents. In polar solvents, {[Ni](PF₆)}₂ may disproportionate to [Ni] and 3,5-DTBBQ at 323 K, thereby demonstrating a significant solvent- and metal-dependence in temperature. The relative activities of {[Ni](PF₆)}₂ and [M](PF₆) toward disproportionation are related to the electrochemically estimated K_dis values in CH₂Cl₂ and DMF. The present work demonstrates that solvent polarity and the dipole moments of the SQ complexes promote disproportionation, which can be controlled by a judicious choice of the metal ion, solvent, and temperature.     

Addition of Alkynes to High Nuclearity Platinum–Ruthenium Carbonyl Cluster Complexes

The reactions of the mixed metal cluster complexes PtRu₅(CO)₁₆(μ₆-C)[Pt(PBu )], 5 and PtRu₅(CO)₁₆(μ₆-C)[Pt(PBu ]₂, 6 with selected alkynes have been investigated. Compound 5 adds one and two equivalents of PhC₂H to yield the new compounds PtRu₅(CO)₁₅(μ₆-C)(μ₃-PhC₂H)[Pt(PBu )], 8 and PtRu₅(CO) -C)( -PhC₂H)₂[Pt(PBu )], 9 at 40 and 68°C, respectively. Compound 6 was found to react with PhC₂H at 40°C to yield the new compound PtRu₅(CO) -C)( -PhC₂H)[Pt(PBu )]₂, 10. The reaction of 6 with PhC₂Ph at 97°C yielded the new compound PtRu₅(CO) -C)( -PhC₂Ph)₂[Pt(PBu )]₂, 11. All products were characterized crystallographically by single crystal X-ray diffraction techniques. The structure of 8 consists of a pseudo-octahedral PtRu₅ cluster with a second platinum atom bridging a basal edge of the Ru₅ square pyramid. A triply bridging PhC₂H ligand is bonded to the two platinum atoms and one of the ruthenium atoms. The structure of 9 consists of a nido-dodecahedral Pt₂Ru₅ cluster with a carbido ligand in the interior that is not bonded to all seven of the metal atoms. It also contains two triply bridging PhC₂H ligands. The structure of 10 consists of a central octahedral cluster of five ruthenium atoms and one platinum atom. Two additional platinum atoms are bonded to the platinum atom in this cluster but these atoms are not bonded to any other metal atoms of the PtRu₅ cluster. A triply bridging PhC₂H ligand is coordinated to the group of three platinum atoms. The structure of 11 consists of an octahedral PtRu₅ cluster with two additional platinum atoms capping two PtRu₂ triangular faces. There are two PhC₂Ph ligands bridging two Ru₃ triangular faces of the central octahedron. This report is dedicated to Professor Ilya Moiseev on the occasion of his 75th birthday for his many pioneering contributions to the chemistry of metal clusters.     

Synthesis of Mixed-Ligand Nitrileand Carbonyl–Isocyanide Complexes of Platinum(II) and Their Reaction with P-Toluenesulfonyl Hydrazide

Mixed-ligand nitrile- and carbonyl-isocyanide complexes of platinum(II) trans-[PtCl₂(NCEt)CNXyl] and trans-[PtCl₂(CO)CNXyl] (Xyl = 2,6-Me₂C₆H₃) have been prepared for the first time. The compounds have been characterized by mass spectrometry, IR and NMR spectroscopy. Reactivity of the prepared complexes towards N-nucleophiles has been studied using the reaction with p-toluenesulfonyl hydrazide as the example.     

Synthesis and Molecular Structure of Binuclear Tin（Ⅳ）Complex Bridged by Terephthalate Anion

The title complex [Ph₃Sn(CH₃OH) (terephthalate) (CH₃OH) SnPh₃]·2CH₃OH was synthesized by the reaction of Ph₃SnCl with terephthalate in the molar ratio of 2:1 in methanol solution and characterized by elemental analysis, IR and ¹H NMR spectra, and the crystal structure was determined by X‐ray single crystal diffraction study. The crystal belongs to monoclinic with space group P2₁/n, a = 1.5199(5) nm, b = 0.9000(3) nm, c = 1.8206(6) nm, β= 113.970(5)°, Z = 2, V = 2.2755 (13) nm³, D_c= 1.413 g/cm³, μ = 1.146 mm^?1, F(000) = 980, R =0.0353, wR = 0.0606. In the crystals of complex, the tin atoms rendered five‐coordinate in a distorted trigonal bipyramidal structure.     

Syntheses, Spectral Studies and Bioanalyses of Some Triorganotin(Ⅳ) Complexes of Cephlaxine

Five novel triorganotin(Ⅳ) complexes have been synthesized by refluxing trimethyl, triethyl, tributyl, triphenyl and tribenzyltin chloride with Cephlaxine.These compounds were characterized by spectroscopic (IR,1H, 13C, 119Sn NMR) techniques and elemental analysis.The results obtained through these techniques are in full agreement with the proposed 1:1 stoichiometry.The synthesized compounds were than tested against various microorganisms and fungi.The results of new products obtained showed that the triphenyltin(IV) complex displayed promising activity against all types of bacteria and fungi used while all other compounds showed significant antibacterial and antifungal activity.