β‐Diketiminate‐Stabilized Magnesium(I) Dimers and Magnesium(II) Hydride Complexes: Synthesis,Characterization, Adduct Formation,and Reactivity Studies

The preparation and characterization of a series of magnesium(II) iodide complexes incorporating β‐diketiminate ligands of varying steric bulk and denticity, namely, [(ArNCMe)₂CH]^? (Ar=phenyl, (^PhNacnac), mesityl (^MesNacnac), or 2,6‐diisopropylphenyl (Dipp, ^DippNacnac)), [(DippNCtBu)₂CH]^? (^tBuNacnac), and [(DippNCMe)(Me₂NCH₂CH₂NCMe)CH]^? (^DmedaNacnac) are reported. The complexes [(^PhNacnac)MgI(OEt₂)], [(^MesNacnac)MgI(OEt₂)], [(^DmedaNacnac)MgI(OEt₂)], [(^MesNacnac)MgI(thf)], [(^DippNacnac)MgI(thf)], [(^tBuNacnac)MgI], and [(^tBuNacnac)MgI(DMAP)] (DMAP=4‐dimethylaminopyridine) were shown to be monomeric by X‐ray crystallography. In addition, the related β‐diketiminato beryllium and calcium iodide complexes, [(^MesNacnac)BeI] and [{(^DippNacnac)CaI(OEt₂)}₂] were prepared and crystallographically characterized. The reductions of all metal(II) iodide complexes by using various reagents were attempted. In two cases these reactions led to the magnesium(I) dimers, [(^MesNacnac)MgMg(^MesNacnac)] and [(^tBuNacnac)MgMg(^tBuNacnac)]. The reduction of a 1:1 mixture of [(^DippNacnac)MgI(OEt₂)] and [(^MesNacnac)MgI(OEt₂)] with potassium gave a low yield of the crystallographically characterized complex [(^DippNacnac)Mg(μ‐H)(μ‐I)Mg(^MesNacnac)]. All attempts to form beryllium(I) or calcium(I) dimers by reductions of [(^MesNacnac)BeI], [{(^DippNacnac)CaI(OEt₂)}₂], or [{(^tBuNacnac)CaI(thf)}₂] have so far been unsuccessful. The further reactivity of the magnesium(I) complexes [(^MesNacnac)MgMg(^MesNacnac)] and [(^tBuNacnac)MgMg(^tBuNacnac)] towards a variety of Lewis bases and unsaturated organic substrates was explored. These studies led to the complexes [(^MesNacnac)Mg(L)Mg(L)(^MesNacnac)] (L=THF or DMAP), [(^MesNacnac)Mg(μ‐AdN₆Ad)Mg(^MesNacnac)] (Ad=1‐adamantyl), [(^tBuNacnac)Mg(μ‐AdN₆Ad)Mg(^tBuNacnac)], and [(^MesNacnac)Mg(μ‐tBu₂N₂C₂O₂)Mg(^MesNacnac)] and revealed that, in general, the reactivity of the magnesium(I) dimers is inversely proportional to their steric bulk. The preparation and characterization of [(^tBuNacnac)Mg(μ‐H)₂Mg(^tBuNacnac)] has shown the compound to have different structural and physical properties to [(^tBuNacnac)MgMg(^tBuNacnac)]. Treatment of the former with DMAP has given [(^tBuNacnac)Mg(H)(DMAP)], the X‐ray crystal structure of which disclosed it to be the first structurally authenticated terminal magnesium hydride complex. Although attempts to prepare [(^MesNacnac)Mg(μ‐H)₂Mg(^MesNacnac)] were not successful, a neutron diffraction study of the corresponding magnesium(I) complex, [(^MesNacnac)MgMg(^MesNacnac)] confirmed that the compound is devoid of hydride ligands.     

Synthesis,Characterization and Photophysical Properties of Iridium(III) Bis‐cyclometallated Complexes Containing 1,1‐Dithiolates

A series of neutral Ir(III)‐based heteroleptic complexes with a formula of [Ir(η²‐(C^∧N))₂(η²‐(S^∧S))] ((C^∧N)^‐ = ppy^‐, (S^∧S)^‐ = Et₂NCS₂^‐ ( 2a ), MeOCS₂^‐ ( 2b ), EtOCS₂^‐ ( 2c ), ⁱPrOCS₂^‐ ( 2d ); (C^∧N)^‐ = tpy^‐, (S^∧S) = Et₂NCS₂^‐ ( 3a ), MeOCS₂^‐ ( 3b ), EtOCS₂^‐ ( 3c ), ⁱPrOCS₂^‐ ( 3d ); (C^∧N)^‐ = epb^‐ , (S^∧S)^‐ = Et₂NCS₂^‐ ( 4a ), MeOCS₂^‐ ( 4a ), EtOCS₂^‐ ( 4a ); ppyH = 2‐phenylpyridine; tpyH = 2‐(4′‐tolyl)pyridine; epbH = ethyl 4‐(2′‐pyridyl)benzate) was synthesized and characterized. The crystal structure of complex 2d was also determined. The electron‐releasing substituents on (C^∧N)^‐ or (S^∧S)^‐ blueshift λ_max values.     

An alternative route for the preparation of the medical isotope 99Mo from the 238U(γ, f) and 100Mo(γ, n) reactions

The radionuclide ⁹⁹Mo, which has a half-life of 65.94 h was produced from ²³⁸U(γ, f) and ¹⁰⁰Mo(γ, n) reactions using a 10 MeV electron linac at EBC, Kharghar Navi-Mumbai, India. This has been investigated since the daughter product ^99mTc is very important from a medical point of view and can be produced in a generator from the parent ⁹⁹Mo. The activity of ⁹⁹Mo was analyzed by a γ-ray spectrometric technique using a HPGe detector. From the detected γ-rays activity of 140.5 and 739.8 keV, the amount of ⁹⁹Mo produced was determined. For comparison, the amount of ⁹⁹Mo from ²³⁸U(γ, f) and ¹⁰⁰Mo(γ, n) reactions was also estimated using the experimental photon flux from ¹⁹⁷Au(γ, n)¹⁹⁶Au reaction. The amount of ⁹⁹Mo from the detected γ-lines is in agreement with the estimated value for ²³⁸U(γ, f) and ¹⁰⁰Mo(γ, n) reactions. The production of ⁹⁹Mo activity from ²³⁸U(γ, f) and ¹⁰⁰Mo(γ, n) reactions is a relevant and novel approach, which provides alternative routes to ^235,238U(n, f) and ⁹⁸Mo(n, γ) reactions, circumventing the need for a reactor. The viability and practicality of the ⁹⁹Mo production from the ²³⁸U(γ, f) and ¹⁰⁰Mo(γ, n) reactions alternative to ^235,238U(n, f) and ⁹⁸Mo(n, γ) reactions has been emphasize. An estimate has been also arrived based on the experimental data of present work to fulfill the requirement of DOE.     

Synthese und spektroskopische Charakterisierung einiger Pentacarbonylwolfram(0)‐Komplexe mit monound bicyclischen Phosphiran‐Liganden: Kristallstruktur von [{(Me3Si)2HCPC(H)H–C(H)Ph}W(CO)5]

Synthesis and Spectroscopic Characterisation of some Pentacarbonyltungsten(0) Complexes with Mono‐ and Bicyclic Phosphirane Ligands: Crystal Structure of [{(Me₃Si)₂HCPC(H)H–C(H)Ph}W(CO)₅] The tungsten(0) complex [{(Me₃Si)₂HCPC(Ph)=N}W(CO)₅] ( 1 ) reacts upon heating with alkene derivatives 2 , 6 , 8 , and 10 in toluene to form benzonitrile and the complexes [{(Me₃Si)₂HCPC(R¹,R²)–C(R³,R⁴}W(CO)₅] ( 4 , 7 a , b , 9 a , b , 11 a , b ) ( 4 (trans): R¹,R³ = Ph, R²,R⁴ = H, 7 a , b (cis, meso and rac): R¹,R³ = Ph, R²,R⁴ = H, 9 a , b (RR und SS): R¹ = Ph, R²,R³,R⁴ = H, 11 a , b : R¹=R³ = (CH₂)₄, R²,R⁴ = H). Spectroscopic and mass spectrometric data are discussed. The structure of the complex 9 a was determined by X‐ray single crystal structure analysis showing characteristic data for the phosphirane ring such as a narrow angle at phosphorus (49,2(2)°), different P–C distances (P–C(6) 182,1(5) and P–C(7) 185,2(4) pm) and 152,9(6) pm for the basal C–C bond.     

Direct Resonance Raman Characterization of a Peroxynitrito Copper Complex Generated from O2 and NO and Mechanistic Insights into Metal‐Mediated Peroxynitrite Decomposition

We report the formation of a new copper peroxynitrite ( PN ) complex [Cu^II(TMG₃tren)(κ¹‐OONO)]⁺ ( PN1 ) from the reaction of [Cu^II(TMG₃tren)(O₂^.?)]⁺ ( 1 ) with NO^._(g) at ?125 °C. The first resonance Raman spectroscopic characterization of such a metal‐bound PN moiety supports a cis κ¹‐(^?OONO) geometry. PN1 transforms thermally into an isomeric form ( PN2 ) with κ²‐O,O′‐(^?OONO) coordination, which undergoes O?O bond homolysis to generate a putative cupryl (LCu^II?O^.) intermediate and NO₂^.. These transient species do not recombine to give a nitrato (NO₃^?) product but instead proceed to effect oxidative chemistry and formation of a Cu^II–nitrito (NO₂^?) complex ( 2 ).     

Formation et désactivation par l'oxygène moléculaire de l'atome métastable O(5S) dans une décharge oxygène-hélium

O(⁵S) metastable atom production is studied in a microwave induced plasma (2450 MHz, 320 W) as a function of pressure (0.5 to 10 Torr) and oxygen concentration in helium (0 to 15 % O₂). O(⁵S) and He(³S) densities, electron temperature and electron density are determined. Measurements are performed by optical absorption for metastable species and by double probes for electron temperature and density.Results show that: -O(⁵S) density increases and reaches a maximum with increasing pressure and increasing oxygen concentration, then decreases, while He(³S) decreases continuously; -electron temperature decreases with oxygen concentration and with pressure; -electron density variation is a weak function of oxygen concentration and increases with pressure.According to the results obtained a mechanism for O(⁵S) production and destruction is proposed. Assuming a steadystate, the quenching rate constant of O(⁵S) by O₂ was estimated to be: (1.2 ± 0.4) × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹.     

Cleavage of Carbon Dioxide C=O Bond Promoted by Nickel-Boron Cooperativity in a PBP-Ni Complex

The synthesis and characterization of (^tBuPBP)Ni(OAc) ( 5 ) by insertion of carbon dioxide into the Ni−C bond of (^tBuPBP)NiMe ( 1 ) is presented. An unexpected CO₂ cleavage process involving the formation of new B−O and Ni−CO bonds leads to the generation of a butterfly-structured tetra-nickel cluster (^tBuPBOP)₂Ni₄(μ-CO)₂ ( 6 ). Mechanistic investigation of this reaction indicates a reductive scission of CO₂ by O-atom transfer to the boron atom via a cooperative nickel-boron mechanism. The CO₂ activation reaction produces a three-coordinate (^tBuP₂BO)Ni-acyl intermediate ( A ) that leads to a (^tBuP₂BO)−Ni^I complex ( B ) via a likely radical pathway. The Ni^I species is trapped by treatment with the radical trap (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) to give (^tBuP₂BO)Ni^II(η²-TEMPO) ( 7 ). Additionally, ¹³C and ¹H NMR spectroscopy analysis using ¹³C-enriched CO₂ provides information about the species involved in the CO₂ activation process.     

Cross section measurements for (n, p) and (n, 2n) reactions of rare-earth isotopes at neutron energies from 13.5 to 14.6 MeV

Cross sections for (n, p) and (n, 2n) reactions have been measured on some rare-earth isotopes at neutron energies of 13.5-14.6 MeV using activation technique. Data are reported for the following reactions:¹⁵⁰Nd(n, 2n) ¹⁴⁹Nd, ¹⁴⁸Nd(n, 2n) ¹⁴⁷Nd, ¹⁴²Nd(n, 2n) ¹⁴¹Nd, ¹⁶⁰Gd(n, 2n) ¹⁵⁹Gd, ¹⁵⁸Gd(n, p) ¹⁵⁸Eu, ¹⁴⁶Nd(n, p) ¹⁴⁶Pr, ¹⁴¹Pr(n, p) ¹⁴¹Ce and ¹³⁹La(n, p) ¹³⁹Ba. The neutron fluences are determined by the cross sections of ²⁷Al(n, a) ²⁴Na and ⁹³Nb(n, 2n) ^92mNb reactions. This revised version was published online in August 2006 with corrections to the Cover Date.     

Redox Non‐Innocence of Nitrosobenzene at Nickel

Nitrosobenzene (PhNO) serves as a stable analogue of nitroxyl (HNO), a biologically relevant, redox‐active nitric oxide derivative. Capture of nitrosobenzene at the electron‐deficient β‐diketiminato nickel(I) complex [ⁱPr₂NN_F6]Ni results in reduction of the PhNO ligand to a (PhNO)^./? species coordinated to a square planar Ni^II center in [ⁱPr₂NN_F6]Ni(η²‐ONPh). Ligand centered reduction leads to the (PhNO)^2? moiety bound to Ni^II supported by XAS studies. Systematic investigation of structure–reactivity patterns of (PhNO)^./? and (PhNO)^2? ligands reveals parallels with superoxo (O₂)^./? and peroxo (O₂)^2? ligands, respectively, and forecasts reactivity patterns of the more transient HNO ligand.     

Dynamics of reactions of O(3P) atoms with CS,CS2 and OCS

The reactions of CS(X ¹Σ⁺), CS₂(X ¹Σ⁺_g) and OCS(X ¹Σ⁺) with O(³P) were studied at 298 K by means of a CO laser resonance absorption technique. The CO(ν) population distribution produced from the reaction O(³P) + CS(X ¹Σ⁺) studied in a quartz flash photolysis tube (λ>/ 200 nm) is similar to distributions observed previously for ν> 7. For ν < 7 an energetically colder vibrational population was observed which is attributed to the reaction of O(³P) atoms with undissociated CS₂(X ¹Σ⁺_g). Subsequent experiments carried out in a Pyrex flash photolysis tube (λ>/ 300 nm) in which the O(³P) + CS₂(X ¹Σ⁺_g) reaction is the only one which can occur confirmed that the colder population observed is attributable to this process. The branching ratio for the reaction channel O(³P) + CS₂(X ¹Σ⁺_g) → CO(X ¹Σ⁺) + S₂(³Σ^?_g) has been measured. We find that 1.4 ± 0.2% of the O + CS₂ reaction proceeds through this channel, and that the rate constant for this reaction channel is, k = 3.5 (±0.5) × 10¹⁰ cm³/mole s. Isotope labeled experiments using ¹⁸O atoms show that the O(³P) + OCS(X ¹Σ⁺) reaction takes place by a direct stripping mechanism, wherein CO(ν) is produced exclusively from the parent OCS molecule. The CO(ν) formed in this reaction carries about 9% of the total available energy.     

Barium as Honorary Transition Metal in Action: Experimental and Theoretical Study of Ba(CO)+ and Ba(CO)−

Ba(CO)⁺ and Ba(CO)^? have been produced and isolated in a low‐temperature neon matrix. The observed C?O stretching wavenumber for Ba(CO)⁺ of 1911.2 cm^?1 is the most red‐shifted value measured for any metal carbonyl cations, indicating strong π backdonation of electron density from Ba⁺ to CO. Quantum chemical calculations indicate that Ba(CO)⁺ has a ²Π reference state, which correlates with the ²D(5d¹) excited state of Ba⁺ that comprises significant Ba⁺(5d_π¹)→CO(π* LUMO) backbonding, letting the Ba(CO)⁺ complex behave like a conventional transition‐metal carbonyl. A bonding analysis shows that the π backdonation in Ba(CO)⁺ is much stronger than the Ba⁺(5d_σ/6s)←CO(HOMO) σ donation. The Ba⁺ cation in the ²D(5d¹) excited state is a donor rather than an acceptor. Covalent bonding in the radical anion Ba(CO)^? takes place mainly through Ba(5d_π)←CO^?(π* SOMO) π donation and Ba(5d_σ/6s)←CO^?(HOMO) σ donation. The most important valence functions at barium in Ba(CO)⁺ cation and Ba(CO)^? anion are the 5d orbitals.     

Ab-initio calculations of excited rare gas alkali ions

The excimer-like ions formed by combining a rare gas ion with an alkali atom were investigated by an ab initio HF-CI calculation. The resulting four bound excited states¹Σ⁺,¹Π,³Σ⁺ and³Π were subjected to a semiempirical spin orbit (SO)-coupling yielding eight fine structure levels with angular momenta Ω=2, 1(3) and 0(4). For (NeLi)⁺, (NeNa)⁺, (ArLi)⁺, (ArNa)⁺, (ArK)⁺ and (KrLi)⁺ the wavelengths for the five allowed transitions to the ground state were calculated. The results are in close agreement with the experimental results. Also other spectroscopic properties as binding energies, transition moments and vibrational quanta are given.     

Conversion of E4 (E4=P4, As4, AsP3) by Ni(0) and Ni(I) Synthons – A Comparative Study

The reactivity of white phosphorus and yellow arsenic towards two different nickel nacnac complexes is investigated. The nickel complexes [(L¹Ni)₂tol] ( 1 , L¹=[{N(C₆H₃ⁱPr₂-2,6)C(Me)}₂CH]⁻) and [K₂][(L¹Ni)₂(μ,η^{1 : 1}-N₂)] ( 6 ) were reacted with P₄, As₄ and the interpnictogen compound AsP₃, respectively, yielding the homobimetallic complexes [(L¹Ni)₂(μ-η²,κ¹:η²,κ¹-E₄)] (E=P ( 2 a ), As ( 2 b ), AsP₃ ( 2 c )), [(L¹Ni)₂(μ,η^{3 : 3}-E₃)] (E=P ( 3 a ), As ( 3 b )) and [K@18-c-6(thf)₂][L¹Ni(η^{1 : 1}-E₄)] (E=P ( 7 a ), As ( 7 b )), respectively. Heating of 2 a , 2 b or 2 c also leads to the formation of 3 a or 3 b . Furthermore, the reactivity of these compounds towards reduction agents was investigated, leading to [K₂][(L¹Ni)₂(μ,η^{2 : 2}-P₄)] ( 4 ) and [K@18-c-6(thf)₃][(L¹Ni)₂(μ,η^{3 : 3}-E₃)] (E=P ( 5 a ), As ( 5 b )), respectively. Compound 4 shows an unusual planarization of the initial Ni₂P₄-prism. All products were comprehensively characterized by crystallographic and spectroscopic methods.     

Mononukleare und mehrfach verbrückte dinukleare Phthalocyaninate(1–/2–) des Yttriums durch Solvenz‐kontrollierte Kondensation; kleine Solvenz‐Cluster als Liganden

Mononuclear and Multiply Bridged Dinuclear Phthalocyaninates(1–/2–) of Yttrium by Solvent Controlled Condensation; Small Solvent Clusters as Ligands Green chlorophthalocyaninato(2–)yttrium(III), [Y(Cl)pc^2–] forms when yttrium chloride is heated with o‐phthalonitrile in 1‐chloronaphthalene. Black cis‐di(chloro)phthalocyaninato(1‐)yttrium(III), ^cis[Y(Cl)₂pc^–] is obtained as a stable intermediate by partial reduction. Both complexes are soluble in many O‐donor solvents and pyridine. The solubility in water is remarkable: [Y(Cl)pc^2–] dissolves with green, ^cis[Y(Cl)₂pc^–] with red‐violet color. Typical absorptions of the pc^2– ligand are observed at 14800 and 29700 cm^–1. A solvent dependent monomer‐dimer equilibrium is found for the pc^– radical. The monomer with absorptions at 12100 and 19900 cm^–1 is favored in non‐polar solvents, while in polar solvents the dimer with absorptions at 8700, 13200 and 18600 cm^–1 is preferred. cis‐Tri(dimethylformamide)chlorophthalocyaninato(2–)yttrium(III) etherate ( 1 ) crystallises from a solution of [Y(Cl)pc^2–] in MeOH/dmf, cis‐tetra(dimethylsulfoxide)phthalocyaninato(2–)yttrium(III) chloride etherate methanol disolvate ( 2 ) from thf/dmso, μ‐di(chloro)‐μ‐di〈di(pyridine)(μ‐water)〉di(phthalocyaninato(2–)‐ yttrium(III)) ( 5 ) from py, and cis‐(chloro)pyridine(triphenylphosphine oxide)phthalocyaninato(2–)yttrium(III) semi‐etherate ( 3 ) is obtained from a solution of [Y(Cl)pc^2–] and triphenylphosphine oxide in py. 1 condenses in MeOH yielding a (1 : 1)‐mixture ( 4 ) of μ‐di(chloro)di(〈trans‐(diwaterdimethanol)〉〈dimethanol〉phthalocyaninato(2–)yttrium(III)) ( 4 a ) and μ‐di(chloro)di(dimethylformamide〈dimethanol〉phthalocyaninato(2–)yttrium(III)) ( 4 b ); co‐ordinatively bound solvent clusters are in brakets. The structures of 1 – 5 have been established by X‐ray crystallography. Apart from 3 with hepta‐co‐ordinated yttrium, the metal ion prefers octa‐co‐ordination, and the bond arrangement around Y³⁺ is always a distorted quadratic antiprism. In the dinuclear complexes obtained by solvent controlled condensation both antiprisms share an edge by two μ‐Cl atoms in 4 , while in 5 the antiprisms are face‐shared by two trans positioned μ‐Cl atoms and μ‐O atoms, respectively. In 5 , the bent ^b〈{py}₂(μ‐H₂O)〉 cluster is stabilised by a combined interplanar bonding of pyridine by short N…H–O bonds (d(N…O) = 2.664(7) Å; 2.81(2) Å) and strong van‐der‐Waals interactions with the ecliptic pc^2– ligands. 4 a and 4 b contain the dimeric methanol cluster 〈(MeOH)₂〉, and 4 a in addition the cyclic heterotetrameric trans‐diwaterdimethanol cluster, trans^c〈(H₂O)₂(MeOH)₂〉. The neutral clusters co‐ordinatively bound to the Y atom are compared with structurally established cluster‐anions of type 〈(OMe)(MeOH)〉^–, linear ^l〈(OMe)(MeOH)₂〉^–, cyclic ^c〈(OH)₃(H₂O)₃〉^3–, ^b〈{H₂O}₂(μ‐O)〉^2–, and ^b{H₂O}₂(μ‐F)〉^–.     

Reactive regioregular oligothiophenes and polythiophenes with Zincke salt structure: Synthesis,reactions, and chemical properties

Polythiophenes with reactive Zincke salt structure, P4ThPy⁺DNP(Cl^?)‐a and P5ThPy⁺DNP(Cl^?)‐a , were synthesized by the oxidation polymerization of oligothiophenes, such as 3'‐(4‐N‐(2,4‐dinitrophenyl)pyridinium chloride)?2,2':5',2'';5'',2'''‐quarterthiophene ( 4ThPy⁺DNP(Cl^?) ) and 4''‐(4‐N‐(2,4‐dinitrophenyl)pyridinium chloride)?2,2';5',2'';5'',2''';5''',2''''‐quinquethiophene ( 5ThPy⁺DNP(Cl^?) ), with iron(III) chloride. The reaction of P5ThPy⁺DNP(Cl^?)‐a with R‐NH₂ [R = n‐hexyl (Hex) and phenyl (Ph)] substituted the 2,4‐dinitrophenyl group into the R group with the elimination of 2,4‐dinitroaniline to yield P5ThPy⁺R(Cl^?) . Similarly, model compounds, 4ThPy⁺R(Cl^?) and 5ThPy⁺R(Cl^?) (R = Hex and Ph), were also synthesized. In contrast to the photoluminescent 4ThPy and 5ThPy , the compounds P4ThPy⁺DNP(Cl^?)‐a , P5ThPy⁺DNP(Cl^?)‐a , and P5ThPy⁺R(Cl^?) showed no photoluminescence because their internal pyridinium rings acted as quenchers. Cyclic voltammetry measurements suggested that P4ThPy⁺DNP(Cl^?)‐a , P5ThPy⁺DNP(Cl^?)‐a , and P5ThPy⁺R(Cl^?) received an electrochemical reduction of the pyridinium and 2,4‐dinitrophenyl groups and oxidation of the polymer backbone. P4ThPy⁺DNP(Cl^?)‐a and P5ThPy⁺DNP(Cl^?)‐a were electrically conductive (ρ = 3.0 × 10 ^{? 6} S cm ^{? 1} and 2.1 × 10 ^{? 6} S cm ^{? 1}, respectively) in the nondoped state. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 481–492     

Characterization of 99mTc(CO)3-iminodiacetic acid (IDA) and its comparison with 99mTc-(IDA)2 using compounds for hepatobiliary scintigraphy

The organometallic precursor of fac-[^99mTc(CO)₃(H₂O)₃]⁺ has attracted much attention because of the robustness and small size of Tc(I)-tricarbonyl complexes compared to Tc(V) complexes and the good labeling affinity with a variety of donor atoms. Among various ligand systems, an iminodiacetic acid (IDA) was proven as a good chelating group to form a Tc(III)-compelx as well as has been shown its potential as a chelating system for fac-[^99mTc(CO)₃] precursor. In an attempt to confirm the similarity and the difference between ^99mTc(CO)₃-IDA and ^99mTc-(IDA)₂-complex, M(CO)₃-IDA (M = ^99mTc, Re) complexes of disofenin, mebrofenin and N-(3-iodo-2,4,6-trimethyl phenylcarbamoylmethyl) iminodiacetic acid were prepared, and the biological evaluation of ^99mTc(CO)₃-disofenin was performed. The ^99mTc(CO)₃-IDA complexes were prepared with a high radiolabeling yield (>98%) in a quantitative manner and showed a negative charge. The in vivo pharmacokinetic behavior of ^99mTc(CO)₃-disofenin showed a similar biological activity to ^99mTc-(disofenin)₂ in that those complexes were quickly cleared from the blood by the hepatocytes and excreted into the gallbladder and intestine. Accordingly, the ^99mTc(CO)₃-IDA derivatives of disofenin and mebrofenin might be used as hepatobiliary imaging agents. Since an IDA is a promising chelator for ^99mTc-based radiopharmaceutical and the biological properties of ^99mTc(CO)₃-IDA derivative shows similar to that of ^99mTc-complex, a biomolecule containing IDA can be freely radiolabeled with fac-[^99mTc(CO)₃]-precursor or ^99mTc. However, the radiolabeling efficiency and the biological behavior demonstrates the favorable properties of ^99mTc(CO)₃-IDA compound for the development of a new imaging agent.     

On the tri-n-octylammonium chlorocomplexes of Sn(IV) in benzene solution

Extracts with tri-n-octylammonium chlorocomplexes of Sn(IV) of various compositions, included the N-deuterated compounds, were prepared and investigated by IR spectroscopy and conductivity measurements. Three Sn(IV) complexes were found: (TOAH⁺)₂SnCl₆^2? (2:1-complex), TOAH⁺SnCl₅^? (1:1-complex) and a complex with the stoichiometric ratio TOA:Sn(IV) > 2. The cation of the latter contains the groups (TOAH…Cl…HTOA)⁺ and TOAH⁺ and that species is supposed to be a 3:1-complex (TOAH…Cl…HTOA)⁺TOAH⁺SnCl₆^2?.     

Chemiluminescence in the oxidation of sodium anthracenide and pyrenide by a RuIII complex

Chemiluminescence (CL) during oxidation of organosodium compounds of anthracene and pyrene in THF by a Ru(bpy)₃ ²⁺ complex was studied. Excited singlet states of anthracene and pyrene (¹R^*) and a Ru(bpy)₃ ^2+* complex were identified as CL emitters. A mechanism for the generation of the excited states in electron transfer reactions resulting in the formation of Ru(bpy)₃ ^2+* and triplet states of hydrocarbons (³R^*) was proposed. The direct formation of a singlet state from the radical anion is energetically impossible. Therefore¹R^* is generated in the triplet-triplet annihilation³R^*+³R^*→¹R^*+R, whereas Ru(bpy)₃ ^2+* can be formed in the reaction of Ru(bpy)₃ ³⁺ with Ru(bpy)₃ ¹⁺ or by the energy transfer from¹R^* to Ru(bpy)₃ ²⁺. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 609–611, March, 1997.     

13C- und 199Sn-NMR untersuchungen an alkinylstannanen

Chemical shifts δ(¹³C), δ(¹¹⁹Sn) and coupling constants J(¹¹⁹Sn¹³C) for alkynylstannanes of the type R_4-nSn(CCR′)_n (n = 1–4) are reported. The values of ¹J(¹¹⁹Sn¹³C) and ²J(¹¹⁹SnC¹³C) depend upon the nature of the substituent R′. ¹J(¹¹⁹Sn¹³C) in Sn(CCCH₃)₄ is 1168 Hz, much larger than a value predicted in the literature of ca. 700 Hz. The comparison of δ(¹¹⁹Sn) for (CH₃)₂Sn(CCR′)₂ and 1,1,4,4-tetramethyl-1-stannacyclohexadi-2,5-ene suggests that the δ(¹¹⁹Sn) of alkynylstannanes are determined only to a small extent by the diamagnetic anisotropic effect of the CC-triple bond.     

Excitation-transfer studies of n2(a3σ+u) with s atoms and cs molecules

The excitation-transfer reaction N₂(A ³Σ⁺_u) and CS molecules has been studied in a fast-flow reactor at 300 K; the excitation rate constant is (1.8 ^+1.7_−0.9) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹. Excitation to the CS (a) state is favored over excitation to the Cs (a¹Π) state. Excitation transfer from S (³P) to S (¹S) is not a facile reaction and an upper limit to the rate constant k(¹S) ≦ 4 × 10⁻¹³ cm³ atom⁻¹ s⁻¹.