Spin-orbit quenching of Cl(2P(1∕2)) by H2

We report fully-quantum, time-independent, scattering calculations for the spin-orbit quenching of Cl((2)P(1∕2)) by H(2) molecules at low and moderate temperature. Our calculations take into account chemical reaction channels. Cross sections are calculated for total energies up to 5000 cm(-1) which are used to determine, by thermal averaging, state-to-state rate coefficients at temperatures ranging from 50 to 500 K. Spin-orbit relaxation of chlorine is dominated by collisions with H(2) in the rotationally excited states j = 2 and j = 3. In the former case the near-resonant energy transfer is the primary relaxation mechanism. The inclusion of the reactive channel could lead differences compared to pure inelastic calculations. Good agreement is obtained with experimental relaxation measurements at room temperature.     

Crystal Structure of Bridged Dimer Complex of [Yb (H_2O)) (acac)_2 (Ac)]_2

1INTRODUCTIONTheacetylacetonatoisanexcellentbidentateligand.Withittherareearthmetalionscanformsomeseriesofcomplexes,suchasLn(acac)3.nH,O(n=1～4)andLn-(acac)4etc.[1-5i.lntheeventletasampleofthecomplexLn(acac)3.3H,Odis-solveinacetylacetonewhichmixeswithaceticacidforrecrystallization.Asaresultasubstitutionreactionofligandsinthesolutionarises.Anacetylacetonatoandacoor-dinatedwatermolecu1eofLn(acac),.3H,Oaresubstitutedbytwoacetatosandanon-coordinatedwatermoleculeisremoved.Amixedligandandbr…     

A New Preparation of Mo2(CO)8(μ-PPh2)2 and W2(CO)8(μ-PPh2)2 by a Phosphorus-Carbon Bond Cleavage Reaction. Crystal Structure of a New Polymorph of Mo2(CO)8(μ-PPh2)2

A new synthesis of Mo₂(CO)₈(-PPh₂)₂ and W₂(CO)₈(-PPh₂)₂ by the reaction of molybdenum and tungsten hexacarbonyls with a tetraazamacrocyclic ligand containing —CH₂PPh₂ side chains, comprising cleavage of the phosphorus-methylene bond has been performed. The complexes have been investigated by magnetic and spectroscopic measurements and by single-crystal structure analyses. The structural characterization of a new polymorph of Mo₂(CO)₈(-PPh₂)₂ has been described.     

Formation of mixed-metal alkoxides mediated by the reactivity of coordinated pinacol: Synthesis and molecular structures of Ce2Ti2(μ3-O)2(μ,η2-OCMe2CMe2O)4(OPri)4(PriOH)2 and of Ce2Nb2(μ3-O)2(μ,η2-OCMe2CMe2O)4(OPri)6

The addition of pinacol to mixtures of titanium and cerium isopropoxides as well as the use of insoluble titanium and cerium pinacolate synthons was investigated as a route to M-Ce (M=Ti, Nb) species. Pinacol was able to promote the formation of mixed-metal species and the first Ce-Ti and Ce-Nb species namely Ce_2Ti(pin)₂(OPrⁱ)₈ and [M₂Ce₂(μ₃-O)₂(μ,η²pin)₄(OPrⁱ)₆H_x] [M=Ti, x=2; M=Nb, x=0; pin=OCMe₂-COMe₂] were isolated and characterized by FT-IR and ¹H NMR. The latter were also characterized by X-Ray diffraction. Their structures are based on a rhombus compressed along the M⋯M direction with 6-coordinated metals. The pinacolate moieties act as bridging-chelating ligands. The metal–oxygen bond lengths vary according to M–O(pin)<M-μ₃–O<Mμ–O(pin)<Ce–OPrⁱ<Ce–μ₃O.     

Spectroelectrochemical Studies on the Interactions of Complexes of Cu(phen)_2~(2 ) and Cu(bpy)_2~(2 ) with DNA

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Effects of Cu~(2+) on characteristic of SV currents

Applying the patch-clamp technique to vacuoles from Radish we studied the effects of Cu2 on Slow Vacuolar (SV) current’s characteristic. Our results show that Cu2 in bath solution at higher concentration inhibits SV currents and the percentage of inhibition increases with increasing concentration and changes with different voltage. When at lower concentration, Cu2 significantly promotes the SV currents and the promotion ratio decrease with increasing voltage. At the same time, the time constants of activation become lesser after adding Cu2 . These results show that there may be some Cu2 binding sites on SV channels and binding to which can change SV current’s characteristic.     

Facile synthesis of nanoparticles of the molecule-based superconductor κ-(BEDT-TTF)2Cu(NCS)2

Well-dispersed roughly spherical nano-objects of the molecule-based superconductor κ-(BEDT-TTF)₂Cu(NCS)₂ have been prepared in an organic solution by using an easy synthetic route. Long alkyl-chain aconitate esters have been used as growth controlling agents. Nano-objects exhibiting sizes in the 35–120 nm range are made of aggregated individual smaller nanoparticles ranging from 3 to 10 nm. Nanoparticle powders have been studied by X-ray diffraction, high resolution electron microscopy and atomic force microscopy in the conductivity mode.     

Polymorphic Study of 2-(2-benzofuryl) Δ-2 Imidazoline

The compound 2-(2-benzofuryl) Δ-2 imidazoline, has been studied by DSC, TG, X-ray diffraction and thermomicroscopy. We shall see that in the case of a study by DSC this compound presents a strange behaviour, which apparently is in contradiction with the thermodynamic rules. In a case of monotropy, if we have the α-phase (stable) and the γ-phase (metastable), after melting and cooling only theα-phase could crystallise. But this compound can give, according to the rate of cooling, theγ-phase metastable. The rate of cooling is of fundamental importance and the monotropic behaviour of this compound will be explained using the Gibbs function G=f(T) for P=1 atm. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ir(PCy3)2(H)2(H2B-NMe2)]+ as a latent source of aminoborane: probing the role of metal in the dehydrocoupling of H3B⋅NMe2H and retrodimerisation of [H2BNMe2]2

The Ir^III fragment {Ir(PCy₃)₂(H)₂}⁺ has been used to probe the role of the metal centre in the catalytic dehydrocoupling of H₃B?NMe₂H ( A ) to ultimately give dimeric aminoborane [H₂BNMe₂]₂ ( D ). Addition of A to [Ir(PCy₃)₂(H)₂(H₂)₂][BAr^F₄] ( 1 ; Ar^F=(C₆H₃(CF₃)₂), gives the amine‐borane complex [Ir(PCy₃)₂(H)₂(H₃B?NMe₂H)][BAr^F₄] ( 2 a ), which slowly dehydrogenates to afford the aminoborane complex [Ir(PCy₃)₂(H)₂(H₂B? NMe₂)][BAr^F₄] ( 3 ). DFT calculations have been used to probe the mechanism of dehydrogenation and show a pathway featuring sequential BH activation/H₂ loss/NH activation. Addition of D to 1 results in retrodimerisation of D to afford 3 . DFT calculations indicate that this involves metal trapping of the monomer–dimer equilibrium, 2 H₂BNMe₂ ? [H₂BNMe₂]₂. Ruthenium and rhodium analogues also promote this reaction. Addition of MeCN to 3 affords [Ir(PCy₃)₂(H)₂(NCMe)₂][BAr^F₄] ( 6 ) liberating H₂B? NMe₂ ( B ), which then dimerises to give D . This is shown to be a second‐order process. It also allows on‐ and off‐metal coupling processes to be probed. Addition of MeCN to 3 followed by A gives D with no amine‐borane intermediates observed. Addition of A to 3 results in the formation of significant amounts of oligomeric H₃B?NMe₂BH₂?NMe₂H ( C ), which ultimately was converted to D . These results indicate that the metal is involved in both the dehydrogenation of A , to give B , and the oligomerisation reaction to afford C . A mechanism is suggested for this latter process. The reactivity of oligomer C with the Ir complexes is also reported. Addition of excess C to 1 promotes its transformation into D , with 3 observed as the final organometallic product, suggesting a B? N bond cleavage mechanism. Complex 6 does not react with C , but in combination with B oligomer C is consumed to eventually give D , suggesting an additional role for free aminoborane in the formation of D from C .     

Response mechanism of platinum electrode to uncoupled ions(Ⅰ)——Response of platinum electrode to Pb~(2+),Cd~(2+),Ca~(2+) and Mg~(2+)

The transient response mechanism of the platinum electrode to the uncoupled ions may be interpreted with the mixed phase formation (MPF) model of the transient response of precipitate-based ion-selective electrodes to interfering tons for Kxy<<1 It is discovered that the peak height of the transient signal is related to the solubility of M(OH)2 and hydration heat of M2+ The relation between the positive peak height of transient signal of Pb2+ or Cd2+ and lgaM obey tne Nernst equation,while that of Ca2+ or Mg2+ does not.The equilibrium potential is not of Nernst response for all ions.     

Electrochemical oxidative addition of chloride to Rh2(μ-dppm)2(CO)2Cl2

The electrochemical oxidation of trans-Rh₂(μ-dppm)₂(CO)₂Cl₂ (dppm = bis (diphenylphosphino)methane) in the presence of chloride has afforded the new dirhodium(II) unsymmetrical complex Rh₂(μ-dppm)₂(μ-Cl)(CO)Cl₃ which is readily converted to the complex [Rh₂(μ-dppm)₂(μ-Co)(μ-Cl)Cl₂]PF₆. This species has been shown to undergo addition reactions with chloride to regenerate [Rh₂(μ-dppm)₂(μ-Cl)Cl₃(CO)], and with carbon monoxide and t-butylisocyanide to give the additional new dirhodium(II) complexes [Rh₂(μ-dppm)₂(μ-Cl)Cl₂(CO)₂]PF₆ and [Rh₂(μ-dppm)₂(μ-Cl)(CNC(CH₃)₃)₂Cl₂]PF₆, respectively. During prolonged exposure to carbon monoxide [Rh₂(μ-dppm)₂(μ-Co)(μ-Cl)Cl₂]PF₆ undergoes reduction with the loss of chloride to give [Rh₂(μ-dppm)₂(μ-Cl)(CO)₂]PF₆.     

Crystal Structure of a New Allotropic Form of trans-Pd(Creat)2Cl2·2H2O

Pd(creat)₂Cl₂·2H₂O crystallizes in space group P&1macr; with a= 7.257(2), b= 8.159(2), c= 14.640(2) Å, f =73.97(2), g =77.0(1), u =72.22(2)°, Z=2, and represents a new allotropic form of this compound. Pd atoms have planar fourfold coordination of N and Cl atoms in trans configuration. Creatinine moieties are coordinated to the Pd atoms via endocyclic N atoms and their essential planarity causes significant delocalization of electron density. The structure is stabilized by a system of weak hydrogen bonds involving interstitial water molecules and creatinine amino-groups.     

Synthesis and chemistry of tris(2-pyridyl)phosphine and bis(2-pyridyl)phenylphosphine complexes of mercury(II) X (X = Br,Cl) and X-ray crystal structural determination of [HgBr2(PPh(2-py)2)2]

Mercury(II) halide complexes [HgX₂(P(2-py)₃)₂] (X?=?Br (1), Cl (2)) and [HgX₂(PPh(2-py)₂)₂] (X?=?Br (3), Cl (4)) containing P(2-py)₃ and PPh(2-py)₂ ligands (P(2-py)₃ is tris(2-pyridyl)phosphine and PPh(2-py)₂ is bis(2-pyridyl)phenylphosphine) were synthesized in nearly quantitative yield by reaction of corresponding mercury(II) halide and appropriate ligands. The synthesized complexes are fully characterized by elemental analysis, melting point determination, IR, ¹H, and ³¹P-NMR spectroscopies. Furthermore, the crystal structure of [HgBr₂(PPh(2-py)₂)₂] determined by X-ray diffraction is also reported.     

Synthesis of 2-(2-Thienyl)benzimidazoles by the Reaction of 2-(Mercaptomethyl)benzimidazole With β-Electrophilic Esters

New 2-(2-di- and tetrahydrothienyl)benzimidazole compounds were prepared by the ring closure reactions of 2-(mercaptomethyl)benzimidazole^1,2 (1) and α,β-unsaturated compounds activated with electron-withdrawing groups.     

Scope and limitations of the photooxidations of 2-(α-hydroxyalkyl)furans: synthesis of 2-hydroxy-exo-brevicomin

Photooxygenation of 2-(α-hydroxyalkyl)furans at 5 °C in MeOH followed by in situ reduction affords, in one synthetic operation, 6-hydroxy-3(2H)-pyranones and/or 5-hydroxy-2(5H)-furanones. The relative ratio of the final products is highly dependent on the substitution of the starting furan substrate. Photooxygenation of 2-(α,β-dihydroxyalkyl)furans followed by in situ reduction and ketalization with acid rapidly provides the 6,8-dioxabicyclo[3.2.1]oct-3-en-2-one framework. This new methodology was successfully applied to the synthesis of 2-hydroxy-exo-brevicomin.     

Three-body dissociation dynamics of (SO2)3 studied through dissociative photodetachment of (SO2)3−

The dissociative photodetachment dynamics of (SO₂)₃⁻ were studied by photoelectron–photofragment coincidence spectroscopy at 258 nm. Correlation between the photoelectron and photofragment translational energies was observed as previously seen in the dimer system, implying the presence of a dimer core. The three-body dissociation dynamics of (SO₂)₃ after photodetachment are consistent with a dimer core solvated by a spectator SO₂ molecule with a broad distribution in initial geometry.     

Physical Characterization and Reactivity of the Uranyl Peroxide [UO(2)(η(2)-O(2))(H(2)O)(2)]·2H(2)O: Implications for Storage of Spent Nuclear Fuels

The unusual uranyl peroxide studtite, [UO(2)(η(2)-O(2))(H(2)O)(2)]·2H(2)O, is a phase alteration product of spent nuclear fuel and has been characterized by solid-state cyclic voltammetry. The voltammogram exhibits two reduction waves that have been assigned to the U(VI/V) redox couple at -0.74 V and to the U(V/IV) redox couple at -1.10 V. This potential shows some dependence upon the identity of the cation of the supporting electrolyte, where cations with larger ionic radii exhibit more cathodic reduction potentials. Raman spectroelectrochemistry indicated that exhaustive reduction at either potential result in a product that does not contain peroxide linkers and is likely to be UO(2). On the basis of the reduction potentials, the unusual behavior of neptunium in the presence of studtite can be rationalized. Furthermore, the oxidation of other species relevant to the long-term storage of nuclear fuel, namely, iodine and iodide, has been explored. The phase altered product should therefore be considered as electrochemically noninnocent. Radiotracer studies with (241)Am show that it does not interact with studtite so mobility will not be retarded in repositories. Finally, a large difference in band gap energies between studtite and its dehydrated congener metastudtite has been determined from the electronic absorption spectra.     

Quantum chemical study of chlorine-dissociation of oxalyl chloride (ClCO)_2→2Cl+2CO

It is very difficult to study the phenomenon that molecules are decomposed into several pho-tofragments by UV light, as the energy of lamp-house is insufficient. But the bond energy in oxa-lyl chloride is relatively low, for example, D0(ClCOCO-Cl) = 313.92 kJ/mol[1], D0(ClCO-CO) = 35.53 kJ/mol, and D0(Cl-CO) = 27.17 kJ/mol[2], so, oxalyl chloride, as a typical system for the study of multi-channel dissociation, can be dissociated into the four fragments Cl+Cl+CO+CO by the proper UV …