Water Adsorption on Platinum Dioxide and Dioxygen Complex: Matrix Isolation Infrared Spectroscopic and Theoretical Study of Three PtO2–H2O Complexes

The interactions of water molecule with platinum dioxygen complex and dioxide molecule are investigated by means of matrix isolation infrared spectroscopy and density functional calculations. The platinum atoms reacted with dioxygen to form the previously reported Pt(O₂) complex. The Pt(O₂) complex reacted with water molecule to give the Pt(O₂)–H₂O complex, which was characterized to involve hydrogen bonding between one O atom of Pt(O₂) and one H atom of H₂O (structure A ). Upon visible light irradiation, the hydrogen bonded Pt(O₂)???HOH complex rearranged to another Pt(O₂)–H₂O isomer (structure B ), which involves (O₂)Pt???OH₂ interaction. The Pt(O₂)–H₂O complex in structure B can be isomerized to the weakly bound platinum dioxide‐water complex (structure C ) under UV irradiation.     

Properties of TRPO-HNO<Subscript>3</Subscript> complex used for direct dissolution of lanthanide and actinide oxides in supercritical fluid CO<Subscript>2</Subscript>

The mixed trialkylphosphine oxide-nitric acid (TRPO-HNO₃) complex prepared by contacting pure TRPO with concentrated HNO₃ may be used as additives for direct dissolution of lanthanide and actinide oxides in the supercritical fluid carbon dioxide (SCF-CO₂). Properties of the TRPO-HNO₃ complex have been studied. Experimental results show when the initial HNO₃/TRPO volume ratio is varied from 1:7 to 5:1, the concentration of HNO₃ in the TRPO-HNO₃ complex changes from 2.12 to 6.16 mol/L, the [HNO₃]/[TRPO] ratio of the TRPO-HNO₃ complex changes from 0.93 to 3.38, and the content of H₂O in the TRPO-HNO₃ complex changes from 0.97% to 2.70%. All of the density, viscosity and surface tension of the TRPO-HNO₃ complex change with the concentration of HNO₃ in the complex. The protons of HNO₃ and H₂O in the complex undergo rapid exchange to exhibit a singlet resonance peak in NMR spectra with D₂O insert. When the TRPO-HNO₃ complex dissolves in a low dielectric constant solvent, small droplets of HNO₃ appear which can be detected by NMR. Supported by the National Natural Science Foundation of China (Grant No. 20506014)     

Guest Recognition Control Accompanied by Stepwise Gate Closing and Opening of a Macrocyclic Metallohost

Host–guest binding behavior of macrocyclic hosts is significantly influenced by the shapes and sizes of the hosts. In particular, closing/opening the apertures of the hosts controls the guest uptake/release. A post-metalation modification method was used to achieve the open/close conversions. The starting open complex, [LCo₂(pip)₄](OTf)₂, was efficiently converted to the closed complex, [LCo₂(hda)₂](OTf)₂, which has a doubly bridged structure. The conversion of this closed complex to the open complex [LCo₂(hda)₂(OAc)]⁺ was too slow to be completed, but this gate-opening was dramatically accelerated by the addition of Na⁺. The Na⁺ binding was also significantly enhanced by the gate-opening, that is, conversion of [LCo₂(hda)₂]²⁺ to [LCo₂(hda)₂(OAc)]⁺.     

Oxygen‐Atom Transfer Chemistry and Thermolytic Properties of a Di‐tert‐Butylphosphate‐Ligated Mn4O4 Cubane

[Mn₄O₄{O₂P(OtBu)₂}₆] ( 1 ), an Mn₄O₄ cubane complex combining the structural inspiration of the photosystem II oxygen‐evolving complex with thermolytic precursor ligands, was synthesized and fully characterized. Core oxygen atoms within complex 1 are transferred upon reaction with an oxygen‐atom acceptor (PEt₃), to give the butterfly complex [Mn₄O₂{O₂P(OtBu)₂}₆(OPEt₃)₂]. The cubane structure is restored by reaction of the latter complex with the O‐atom donor PhIO. Complex 1 was investigated as a precursor to inorganic Mn metaphosphate/pyrophosphate materials, which were studied by X‐ray absorption spectroscopy to determine the fate of the Mn₄O₄ unit. Under the conditions employed, thermolyses of 1 result in reduction of the manganese to Mn^II species. Finally, the related butterfly complex [Mn₄O₂{O₂P(pin)}₆(bpy)₂] (pin=pinacolate) is described.     

Reactivity and Catalytic Activity of Homobimetallic Vanadium(V) Complex Derived from Bis(5‐chlorosalicylaldehyde)oxaloyldihydrazone Ligand

Homobimetallic vanadium(V) complex of the composition [(CH₃)₂NH₂⁺]₂[(VO₂)₂(sloxCl)].4H₂O was synthesized from the reaction of V₂O₅ with bis(5‐chlorosalicylaldehyde)oxaloyldihydrazone ligand in a 1:1 molar ratio in methanol. The structure of the complex was established by X‐ray crystallography. Reactivity of the complex with H₂O₂ leads to bis (monooxidoperoxidovanadate(V)) [{VO(O₂)}₂(sloxCl)]^2? formation and with HCl, oxidohydroxido complex of composition [(VO (OH)(sloxCl)]^2? was formed. Binding interaction of the complex was also investigated toward protein (BSA) and it was found to be 2.21 x 10⁸ M^?1. The catalytic activity of the complex in the oxidation of alcohols and oxidative bromination of some organic substrates was also studied, and it showed a great potent as a catalyst.     

Synthesis,characterization and DFT calculations of a Re(V)-thiazolidine-2,4-dione complex

This article presents a combined experimental and computational study of a new oxorhenium(V) complex of thiazolidine-2,4-dione (HTDO). The complex has been synthesized by direct reaction of NH₄ReO₄ with thiazolidine-2,4-dione in the presence of Na₂S₂O₆ as a reducing agent. The complex [ReO(TDO)(H₂O)₃](S₂O₈) has been characterized by spectroscopy (FT-IR, NMR, UV-vis, mass), thermogravimetry, microanalysis, and HPL chromatography. The complex was geometrically optimized by DFT with B3LYP level of theory and satisfactory theoretical–experimental agreement was achieved for analysis of IR and NMR data of the complex. Additional information about binding between rhenium and oxo ligand in the complex has been obtained by NBO analysis. The antibacterial activity of the investigated complex has been tested and evaluated.     

Synthesis and structures of new metallocene derivatives of lanthanides. Molecular structures of the complexes (C13H9)2Eu(THF)2 and (C5Me4H)2YbI(THF)

The divalent europium bis-fluorenyl complex (C₁₃H₉)₂Eu(THF)₂ was synthesized by the metathesis reaction of EuI₂(THF)₂ with two equivalents of fluorenylpotassium and by the protolytic substitution of the naphthalene ligand in the (C₁₀H₈)Eu(THF)₂ complex using the reaction with fluorene. According to X-ray diffraction data, the complex displays a skewed sandwich structure, in which one fluorenyl ligand is η⁵-coordinated to the metal atom, whereas the η³-coordination mode makes a great contribution to the coordination of another ligand. The (C₅Me₄H)₂YbI(THF) complex was synthesized by the reaction of YbI₃(THF)₂ with two equivalents of (C₅Me₄H)K. The structure of the complex was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 530–534, March, 2008.     

Synthesis, properties, and structure of dimethylgold(III) complexes [(CH3)2AuI]2 and (CH3)2AuS2CN(C2H5)2

Volatile diethyldithiocarbamate of dimethylgold(III) was prepared by the interaction of dimethylgold(III) iodide with sodium diethyldithiocarbamate. The complex is examined by the elemental analysis, DTA, IR and electronic spectroscopy. The starting dimeric complex [(CH₃)₂AuI]₂ and a novel monomeric volatile gold(III) complex (CH₃)₂AuS₂CN(C₂H₅)₂ with the AuC₂S₂ coordination core were investigated by single crystal X-ray diffraction for the first time.     

Heterometallic mixed-valence complex with a {CoIICoIIICu2O4} core as a new type of cobalt-based oxide cubane

A tetranuclear heterometallic complex formulated as [Co₂Cu₂(L)₃(ea)(H₂O)(NCS)₂], where H₂L = 2-((2-hydroxyethyl)iminomethyl)-phenol and Hea = 2-aminoethanol, has been obtained by self-assembly and characterized by single crystal X-ray diffraction. The crystal structure of the complex represents a new {Co^IICo^IIIM₂} type of cobalt-based oxide cubane complex according to the classification which has been made via CSD structural analysis.     

Syntheses of tris(t-butylisocyanide)bis(tri-p-dimethyl- aminophenylphosphine)cobalt(I) and cobalt(II) perchlorates: a reversal of the usual stabilities of cobalt oxidation states

The complexes [Co(CNCMe₃)₃{P(C₆H₄NMe₂-p)₃}₂](ClO₄)₂ and [Co(CNCMe₃)₃{P(C₆H₄NMe₂ -p)₃}₂]ClO₄ are reported. The Co(II) complex, formed by reaction of excess triarylphos-phine with the alkylisocyanide Co(II) complex, is stable and the favoured product. The Co(I) complex, formed by hydrazine reduction of the Co(II) complex, has limited stability in solution, readily oxidizing to the Co(II) species. Upon prolonged irradiation of the Co(II) complex in acetone, [Co{OP(C₆H₄NMe₂-p)₃}₄](ClO₄)₂ is produced.     

Synthesis,crystal structure,magnetism, and biological activities of an oxo-bridged diiron(III) complex

An unsymmetrical oxo-bridged diiron(III) complex [Fe₂L₂(μ-O)], {H₂L?=?trans-N,N′-bis-(2hydroxy-1-naphthalidehydene)-cyclohexanediamine} has been synthesized and characterized by various physico-chemical techniques. In the complex, each deprotonated bi-anionic L^2? serves as a terminal tetradentate ligand (N₂O₂) and coordinates to one Fe to form a [FeL]⁺ unit. Two [FeL]⁺ units are further linked by an oxo-bridge to construct the binuclear oxo-Fe species with intramolecular Fe–Fe separation of 3.38?Å. Variable-temperature magnetic susceptibility studies revealed a strong antiferromagnetic interaction between two iron centers with J of ?112?cm^?1. The interaction of the complex with CT-DNA was studied by various spectroscopic and viscosity measurements, which indicated that the complex could interact with CT-DNA through intercalation. In addition, the complex is able to cleave pBR322 DNA in the presence of H₂O₂. Furthermore, the interaction of the compound with BSA was also investigated, which indicated that the complex could quench the intrinsic fluorescence of BSA by a static quenching mechanism.     

Thermodynamic stability of neodymium nitrate complex with 1,10-phenanthroline

The thermodynamic stability of neodymium nitrate complex with 1,10-phenanthroline (Phen) was determined by mass spectrometry. The complex was formulated as Nd(NO₃)₃ · 2C₁₂H₈N₂ on the basis of elemental analysis. Mass spectrometry allowed us to characterize the decomposition of Nd(NO₃)₃ · 2C₁₂H₈N₂ thermodynamically. The formation enthalpy of this complex is ?1058.0 kJ/mol.     

Study on Properties of TBP-HNO3 Complex Used for Direct Dissolution of Lanthanide and Actinide Oxides in Supercritical Fluid CO2

The tri-n-butyl phosphate-nitric acid （TBP-HNO3） complex prepared by contacting the pure TBP with the concentrated HNO3 can be used for direct dissolution of lanthanide and actinide oxides in the supercritical fluid carbon dioxide （SCF-CO2）. Properties of the TBP-HNO3 complex have been studied. Experimental results showed that when the initial HNO3/TBP volume ratio was varied from 1 ： 7 to 5 ： 1, the concentration of HNO3 in the TBP-HNO3 complex changed from 1.95 to 5.89 mol/L, the [HNO3]/[TBP] ratio of the TBP-HNO3 complex changed from 0.61 to 2.22, and the content of H20 in the TBP-HNO3 complex changed from 2.02% to 4.19%. All of the density, viscosity and surface tension of the TBP-HNO3 complex changed with the concentration of HNO3 in the complex, and were higher than those of the pure TBE The protons of HNO3 and H2O in the complex underwent rapid exchange to exhibit a singlet resonance peak in nuclear magnetic resonance spectra. When the TBP-HNO3 complex was dissolved in a low dielectric constant solvent, small droplets of HNO3 were formed that can be detected by NMR.     

Synthesis,Characterization, and Fluorescence Chemosensor Properties of a cis‐Dioxomolybdenum(VI) Complex Containing Multidentate Hydrazone Ligands

The homobimetallic molybdenum(VI) complex, [(MoO₂)₂(slsch)(DMF)₂], derived from multidentate hydrazone ligand (H₄slsch = disalicylaldehyde succinoyldihydrazone) was synthesized. The complex was obtained by reaction of the ligand with Mo₂(acac)₂ in 1:2 molar ratio in methanol. It was characterized by using various spectroscopic techniques. The structure of the complex was established by single crystal X‐ray diffraction. The complex shows fluorescence emission, responds toward Al^III ions, and hence it can be used as fluorescence chemosensor for sensing Al^III ions. The sensing properties show that the complex is more efficient and sensitive towards Al^III ions than the rest of the ions used in the presented study.     

Thermal Decomposition of Barium Dioxodiaquaperoxyoxalato Uranate(VI) Hydrate

Barium dioxodiaquaperoxyoxalatouranate was obtained by reaction of uranyl nitrate with oxalic acid and then hydrogen peroxide in the presence of barium ion. The complex was subjected to chemical analysis. The thermal decomposition behaviour of the complex was studied using TG, DTG and DTA techniques. The solid complex salt and the intermediate product of its thermal decomposition were characterized using IR absorption and X-ray diffraction spectra. Based on data from these physico-chemical investigations the structural formula of the complex was proposed as Ba[UO₂(O₂)(C₂O₄)(H₂O)₂]⋅H₂O. This revised version was published online in August 2006 with corrections to the Cover Date.     

Second generation of a polypyridine ligand to mimic enzymes containing non-heme iron centers

A new tetrapyridyl ligand (BDPEA) and the corresponding di-iron(III) μ-oxo complex were synthesized. The iron complex structure, determined by X-ray crystallography, exhibited the dinuclear core [Fe₂^III(BDPEA)₂(μ-O)(NO₃)₂](NO₃)₂ (1). With monopersulfate as oxidant, this complex catalyzed the conversion of 2,4,6-trichlorophenol and catechol, with a better activity and an enhanced life-time compared to the previously reported complex [Fe^III(BDPMA)](NO₃)₃ (2) (BDPMA: bis[di(2-pyridyl)methyl]amine) which contained two fragile benzylic C–H bonds on the tetrapyridyl ligand.     

Synthesis and characterization of novel platinum group metal complexes of bis[2-(diphenylphosphino)ethyl]amine

A mixed donor tridentate ligand bis[2-(diphenylphosphino)ethyl]amine (DPEA) was synthesized in its hydrochloride form by a modified procedure and characterized by ¹H, ¹³C and ³¹P NMR spectral data. Reaction of RhCl(CO)(PPh₃)₂ with DPEA · HCl and NaBPh₄ in methanol gave the cationic Rh(I) complex [Rh(DPEA)PPh₃IBPh₄ but the reaction of IrCl(CO)(PPh₃)₂ with DPEA · HCl in boiling benzene gave a unique complex, [Ir(H)(Cl)(CO)(DPEA)]Cl, in which five different donor atoms are coordinated to the single Ir(III) ion. A neutral, RH(III) complex of the composition [RhCl₃(DPEA)] was prepared by the reaction of RhCl₃ · xH₂O with DPEA · HCl in methanol. Reaction of PdCl₂(COD) with DPEA · HCl in benzene or methanol gave the cationic complex [PdCl(DPEA)]Cl the above reaction conducted in benzene-acetone-methanol mixture gave the 1:2 complex [Pd(DPEA)₂]Cl₂. A novel trinuclear Pt(II) complex of the composition [Pt₃Cl₃(DPEA)₃]Cl₃ was prepared by the reaction of K₂PtCl₄ and DPEA · HCl in water-acetone mixture. Reaction of K₂PtCl₄, DPEA · HCl and NH₄PF₆ in water ethanol mixture gave the binuclear, cationic complex, [Pt₂(DPEA)₃](PF₆)₄. All the complexes were characterized by elemental analysis, conductivity, ¹H and ³¹P NMR spectral data.     

Thermal decomposition of the [Pt(NH3)4]2+ complex in nax zeolite: effect of calcination procedure

The effect of the calcination procedure on the decomposition of the [Pt(NH₃)₄]²⁺ complex in a NaX zeolite was studied by mass spectrometry (MS-TPDE) and diffuse reflectance spectroscopy (DRS). The decomposition of the complex took place in two steps. In the first step, under oxygen, the [Pt(NH₃)₄]²⁺ complex was first converted to [Pt(NH₃)₂]²⁺ complex, accompanied by nitrogen release. In the second step, corresponding to the decomposition of the remaining two amine ligands, NO formation was also observed. Under He, the decomposition also occurred in two steps with H₂ liberation. A reaction scheme was proposed for these results.     

Synthesis and structure of the pyrazolate-bridged cobalt(II) benzoate Co<Subscript>2</Subscript>(μ-dmpz)<Subscript>2</Subscript>(Hdmpz)<Subscript>2</Subscript>(OOCPh)<Subscript>2</Subscript>

The reaction between Co(Hdmpz)₂(OOCPh)₂ and cobalt acetate hydrate leads to the deprotonation of coordinated pyrazole and formation of pyrazolate-bridged Co₂(μ-dmpz)₂(Hdmpz)₂(OOCPh)₂ binuclear complex. The structure of the complex was determined by X-ray crystallography.