Atmospheric chemistry of CF3CF═CH2 and (Z)-CF3CF═CHF: Cl and NO3 rate coefficients, Cl reaction product yields, and thermochemical calculations

Rate coefficients, k, for the gas-phase reactions of Cl atoms and NO(3) radicals with 2,3,3,3-tetrafluoropropene, CF(3)CF═CH(2) (HFO-1234yf), and 1,2,3,3,3-pentafluoropropene, (Z)-CF(3)CF═CHF (HFO-1225ye), are reported. Cl-atom rate coefficients were measured in the fall-off region as a function of temperature (220-380 K) and pressure (50-630 Torr; N(2), O(2), and synthetic air) using a relative rate method. The measured rate coefficients are well represented by the fall-off parameters k(0)(T) = 6.5 × 10(-28) (T/300)(-6.9) cm(6) molecule(-2) s(-1) and k(∞)(T) = 7.7 × 10(-11) (T/300)(-0.65) cm(3) molecule(-1) s(-1) for CF(3)CF═CH(2) and k(0)(T) = 3 × 10(-27) (T/300)(-6.5) cm(6) molecule(-2) s(-1) and k(∞)(T) = 4.15 × 10(-11) (T/300)(-0.5) cm(3) molecule(-1) s(-1) for (Z)-CF(3)C═CHF with F(c) = 0.6. Reaction product yields were measured in the presence of O(2) to be (98 ± 7)% for CF(3)C(O)F and (61 ± 4)% for HC(O)Cl in the CF(3)CF═CH(2) reaction and (108 ± 8)% for CF(3)C(O)F and (112 ± 8)% for HC(O)F in the (Z)-CF(3)CF═CHF reaction, where the quoted uncertainties are 2σ (95% confidence level) and include estimated systematic errors. NO(3) reaction rate coefficients were determined using absolute and relative rate methods. Absolute measurements yielded upper limits for both reactions between 233 and 353 K, while the relative rate measurements yielded k(3)(295 K) = (2.6 ± 0.25) × 10(-17) cm(3) molecule(-1) s(-1) and k(4)(295 K) = (4.2 ± 0.5) × 10(-18) cm(3) molecule(-1) s(-1) for CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF, respectively. The Cl-atom reaction with CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF leads to decreases in their atmospheric lifetimes and global warming potentials and formation of a chlorine-containing product, HC(O)Cl, for CF(3)CF═CH(2). The NO(3) reaction has been shown to have a negligible impact on the atmospheric lifetimes of CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF. The energetics for the reaction of Cl, NO(3), and OH with CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF in the presence of O(2) were investigated using density functional theory (DFT).     

Probing stepwise reaction of NNP-ligand copper(I) complex with elemental sulfur by using N-heterocyclic carbene as a trapper

The dinuclear NNP-ligand copper(I) complex [o-N═CH(C(4)H(3)N)-PPh(2)C(6)H(4)](2)Cu(2) (1) has been synthesized by the reaction of (CuMes)(4) (Mes = 2,4,6-Me(3)C(6)H(2)) with N-((1H-pyrrol-2-yl)-methylene)-2-(diphenylphosphino)benzenamine under an elimination of MesH. Further reaction of 1 with an excess of S(8) produced a mononuclear Cu(II) complex [o-N═CH(C(4)H(3)N)-P(S)Ph(2)C(6)H(4)](2)Cu (5) and CuS. CuS was identified by Raman spectroscopy and 1 and 5 were clearly confirmed by X-ray crystallography. The N-heterocyclic carbene was employed to react with 1 to give a mononuclear [o-N═CH(C(4)H(3)N)-PPh(2)C(6)H(4)]Cu{C[N(iPr)CMe](2)} (2). The reactions of 2 were carried out with (1)/(8), (2)/(8), and (5)/(8) equiv of S(8), leading to compounds [o-N═CH(C(4)H(3)N)-P(S)Ph(2)C(6)H(4)]Cu{C[N(iPr)CMe](2)} (3), [o-N═CH(C(4)H(3)N)-P(S)Ph(2)C(6)H(4)]Cu (4), and 5 respectively, in which CuS was generated in the third reaction and S═C[N(iPr)CMe](2) in the latter two reactions. The clean confirmation of 2-4 demonstrates a stepwise reaction process of 1 with S(8) to 5 and CuS and the N-heterocyclic carbene acts well as a trapping agent.     

Chemically activated reactions on the C7H5 energy surface: propargyl + diacetylene, i-C5H3 + acetylene, and n-C5H3 + acetylene

This study uses computational chemistry and statistical reaction rate theory to investigate the chemically activated reaction of diacetylene (butadiyne, C(4)H(2)) with the propargyl radical (C˙H(2)CCH) and the reaction of acetylene (C(2)H(2)) with the i-C(5)H(3) (CH(2)CCCC˙H) and n-C(5)H(3) (CHCC˙HCCH) radicals. A detailed G3SX-level C(7)H(5) energy surface demonstrates that the C(3)H(3) + C(4)H(2) and C(5)H(3) + C(2)H(2) addition reactions proceed with moderate barriers, on the order of 10 to 15 kcal mol(-1), and form activated open-chain C(7)H(5) species that can isomerize to the fulvenallenyl radical with the highest barrier still significantly below the entrance channel energy. Higher-energy pathways are available leading to other C(7)H(5) isomers and to a number of C(7)H(4) species + H. Rate constants in the large multiple-well (15) multiple-channel (30) chemically activated system are obtained from a stochastic solution of the one-dimensional master equation, with RRKM theory for microcanonical rate constants. The dominant products of the C(4)H(2) + C(3)H(3) reaction at combustion-relevant temperatures and pressures are i-C(5)H(3) + C(2)H(2) and CH(2)CCHCCCCH + H, along with several quenched C(7)H(5) intermediate species below 1500 K. The major products in the n-C(5)H(3) + C(2)H(2) reaction are i-C(5)H(3) + C(2)H(2) and a number of C(7)H(4) species + H, with C(7)H(5) radical stabilization at lower temperatures. The i-C(5)H(3) + C(2)H(2) reaction predominantly leads to C(7)H(4) + H and to stabilized C(7)H(5) products. The title reactions may play an important role in polycyclic aromatic hydrocarbon (PAH) formation in combustion systems. The C(7)H(5) potential energy surface developed here also provides insight into several other important reacting gas-phase systems relevant to combustion and astrochemistry, including C(2)H + the C(3)H(4) isomers propyne and allene, benzyne + CH, benzene + C((3)P), and C(7)H(5) radical decomposition, for which some preliminary analysis is presented.     

Structures of novel R(2)Mo(5)O(18) and R(6)Mo(12)O(45) (R = Eu and Gd) prepared by thermal decomposition of polyoxomolybdate precursor [R2(H2O)(12)Mo(8)O(27)].nH2O

Single crystals of R(2)Mo(5)O(18) and R(6)Mo(12)O(45) (R = Eu and Gd), which are novel compounds in the R(2)O(3)-MoO(3) system, have been obtained by thermal decomposition of [R(2)(H(2)O)(12)Mo(8)O(27)].nH(2)O in air at 750 degrees C for 2 h. TG-DTA and X-ray diffractometry showed that R(2)Mo(5)O(18) crystallizes in a melt of the dehydrated precursor (R(2)Mo(8)O(27)), and R(2)Mo(5)O(18) is transformed to R(6)Mo(12)O(45) in the solid state, both occurring with the loss of MoO(3). R(2)Mo(5)O(18) species crystallize isostructurallyas orthorhombic, Pbcn, Z = 4, with lattice constants of a = 19.2612(7) and 19.246(1) A, b = 9.4618(3) and 9.4414(5) A, c = 9.3779(3) and 9.3446(4) A for R = Eu and Gd, respectively. R(6)Mo(12)O(45) crystallize isostructurally as triclinic P1, Z = 1, with lattice constants of a = 9.3867(4) and 9.3409(3) A, b = 10.9408(5) and 10.8826(5) A, c = 11.4817(5) and 11.4377(5) A, alpha = 104.194(2) degrees and 104.170(1) degrees, beta = 109.567(3) degrees and 109.288(4) degrees, gamma = 108.998(2) degrees and 109.266(2) degrees for R = Eu and Gd, respectively. Both structures consist of [RO(8)] square-antiprisms and [MoO(n)] polyhedra. In R(2)Mo(5)O(18), an [RO(8)] polyhedron is attached by only molybdate groups, being isolated from adjacent [RO(8)] groups. The 12 nearest R atoms surrounding an R atom with R...R distances of 6.0735(4)-7.0389(4) A form an approximate cuboctahedron. All the [RO(8)] square-antiprisms in R(6)Mo(12)O(45) are connected to each other by face-sharing to form dimeric [R(2)O(13)] and [R(2)O(12)] groups. The latter unusual [R(2)O(12)] group is achieved by sharing a square-face via four bridging O atoms with a very short R...R separation (3.4741(7) and 3.4502(6) A for R = Eu and Gd, respectively).     

Organolanthanide-catalyzed intramolecular hydroamination/cyclization/bicyclization of sterically encumbered substrates. Scope, selectivity, and catalyst thermal stability for amine-tethered unactivated 1,2-disubstituted alkenes

This paper reports the organolanthanide-catalyzed intramolecular hydroamination/cyclization of amine-tethered unactivated 1,2-disubstituted alkenes to afford the corresponding mono- and disubstituted pyrrolidines and piperidines using coordinatively unsaturated complexes of the type (eta(5)-Me(5)C(5))(2)LnCH(TMS)(2) (Ln = La, Sm), [Me(2)Si(eta(5)-Me(4)C(5))(2)]SmCH(TMS)(2), and [Me(2)Si(eta(5)-Me(4)C(5))((t)BuN)]LnE(TMS)(2) (Ln = Sm, Y, Yb, Lu; E = N, CH) as precatalysts. [Me(2)Si(eta(5)-Me(4)C(5))((t)BuN)]LnE(TMS)(2) mediates intramolecular hydroamination/cyclization of sterically demanding amino-olefins to afford disubstituted pyrrolidines in high diastereoselectivity (trans/cis = 16/1) and good to excellent yield. In addition, chiral C(1)-symmetric organolanthanide catalysts of the type [Me(2)Si(OHF)(CpR*)]LnN(TMS)(2) (OHF = eta(5)-octahydrofluorenyl; Cp = eta(5)-C(5)H(3); R* = (-)-menthyl; Ln = Sm, Y), and [Me(2)Si(eta(5)-Me(4)C(5))(CpR*)]SmN(TMS)(2) (Cp = eta(5)-H(3)C(5); R* = (-)-menthyl) mediate asymmetric intramolecular hydroamination/cyclization of amines bearing internal olefins and afford chiral 2-substituted piperidine and pyrrolidine in enantioselectivities as high as 84:16 er at 60 degrees C. The substrate of the structure NH(2)CH(2)CMe(2)CH(2)CH=CH(CH(2))(2)CH=CH(2) is regiospecifically bicyclized by [Me(2)Si(eta(5)-Me(4)C(5))((t)BuN)]LnE(TMS)(2) to the corresponding indolizidine skeleton in good yield and high diastereoselectivity. Thermolysis of (eta(5)-Me(5)C(5))(2)LaCH(TMS)(2) in cyclohexane-d(12) at 120 degrees C rapidly releases CH(2)(SiMe(3))(2) and leads to possible formation of fulvene (eta(6)-Me(4)C(5)CH(2)-) species. The thermolysis product readily reverts to active catalysts upon protonolysis by substrate and exhibits the same catalytic activity as the (eta(5),eta(1)-Me(5)C(5))(2)LaCH(TMS)(2) precatalyst at 120 degrees C in the cyclization of cis-2,2-dimethylhept-5-enylamine. Catalytically-active lanthanide-amido complexes (eta(5)-Me(5)C(5))(2)La(NHR)(NH(2)R)(n) and [Me(2)Si(eta(5)-Me(4)C(5))((t)BuN)]Sm(NHR)(NH(2)R)(n) are shown to be thermally robust species.     

Synthesis and structural variations of substituted phenylamide complexes of the heavy alkaline earth metals calcium, strontium and barium

Starting material KN(H)C(6)H(3)-2,6-F(2) was prepared via a transamination reaction from KNH(2) and 2,6-F(2)C(6)H(3)NH(2) in THF and crystallized from 1,4-dioxane (diox) as the three-dimensional polymer [(diox)(1.5)K{N(H)-2,6-F(2)C(6)H(3)}.diox(0.5)](infinity) (1). The metathesis reaction of (THF)(4)CaI(2) with KN(Me)Ph in THF yields monomeric (THF)(4)Ca[N(Me)Ph](2) (2) with a nearly linear N-Ca-N moiety of 179.84(8) degrees . The metathesis reaction of (THF)(4)CaI(2) with KN(H)Mes yields trinuclear (THF)(6)Ca(3)[N(H)Mes](6) (3) with a linear Ca(3) fragment and bridging 2,4,6-trimethylphenylamido groups. The reaction of 1 with (THF)(4)CaI(2) gives dinuclear (THF)(5)Ca(2)[N(H)-2,6-F(2)C(6)H(3)](4).2THF (4) with three bridging and one terminally bound 2,6-difluorophenylamide. A similar reaction of (THF)(5)SrI(2) with KN(H)-2,6-F(2)C(6)H(3) yields dinuclear (THF)(6)Sr(2)[N(H)-2,6-F(2)C(6)H(3)](3)I.THF (5) in which the iodide anion binds terminally. This iodide ligand cannot be substituted as easily by excess KN(H)-2,6-F(2)C(6)H(3). The metathesis reaction of (THF)(5)BaI(2) with KN(H)-2,6-F(2)C(6)H(3) leads to the formation of [(THF)(2)Ba{N(H)-2,6-F(2)C(6)H(3)}(2)](infinity) (6) which crystallizes as a one-dimensional polymer with bridging 2,6-difluorophenylamide anions and additional Ba-F-bonds.     

Thermal decomposition of the perfluorinated peroxides CF3OC(O)OOC(O)F and CF3OC(O)OOCF3

Gas phase thermal decomposition of CF(3)OC(O)OOC(O)F and CF(3)OC(O)OOCF(3) was studied at temperatures between 64 and 98 degrees C (CF(3)OC(O)OOC(O)F) and 130-165 degrees C (CF(3)OC(O)OOCF(3)) using FTIR spectroscopy to follow the course of the reaction. For both substances, the decompositions were studied with N(2) and CO as bath gases. The rate constants for the decomposition of CF(3)OC(O)OOC(O)F in nitrogen and carbon monoxide fit the Arrhenius equations k(N)2 = (3.1 +/- 0.1) x 10(15) exp[-(29.0 +/- 0.5 kcal mol(-1)/RT)] and k(CO) = (5.8 +/- 1.3) x 10(15) exp[-(29.4 +/- 0.5 kcal mol(-1)/RT)], and that for CF(3)OC(O)OOCF(3) fits the equation k = (9.0 +/- 0.9) x 10(13) exp[-(34.0 +/- 0.7 kcal mol(-1)/RT)] (all in units of inverted seconds). Rupture of the O-O bond was shown to be the rate-determining step for both peroxides, and bond energies of 29 +/- 1 and 34.0 +/- 0.7 kcal mol(-1) were obtained for CF(3)OC(O)OOC(O)F and CF(3)OC(O)OOCF(3). The heat of formation of the CF(3)OCO(2)(*) radical, which is a common product formed in both decompositions, was calculated by ab initio methods as -229 +/- 4 kcal mol(-1). With this value, the heat of formation of the title species and of CF(3)OC(O)OOC(O)OCF(3) could in turn be obtained as Delta(f) degrees (CF(3)OC(O)OOC(O)F) = -286 +/- 6 kcal mol(-1), Delta(f) degrees (CF(3)OC(O)OOCF(3)) = -341 +/- 6 kcal mol(-1), and Delta(f) degrees (CF(3)OC(O)OOC(O)OCF(3)) = -430 +/- 6 kcal mol(-1).     

Rare-earth-metal-hydrocarbyl complexes bearing linked cyclopentadienyl or fluorenyl ligands: synthesis, catalyzed styrene polymerization, and structure-reactivity relationship

A series of rare-earth-metal-hydrocarbyl complexes bearing N-type functionalized cyclopentadienyl (Cp) and fluorenyl (Flu) ligands were facilely synthesized. Treatment of [Y(CH(2)SiMe(3))(3)(thf)(2)] with equimolar amount of the electron-donating aminophenyl-Cp ligand C(5)Me(4)H-C(6)H(4)-o-NMe(2) afforded the corresponding binuclear monoalkyl complex [({C(5)Me(4)-C(6)H(4)-o-NMe(μ-CH(2))}Y{CH(2)SiMe(3)})(2)] (1a) via alkyl abstraction and C-H activation of the NMe(2) group. The lutetium bis(allyl) complex [(C(5)Me(4)-C(6)H(4)-o-NMe(2))Lu(η(3)-C(3)H(5))(2)] (2b), which contained an electron-donating aminophenyl-Cp ligand, was isolated from the sequential metathesis reactions of LuCl(3) with (C(5)Me(4)-C(6)H(4)-o-NMe(2))Li (1 equiv) and C(3)H(5)MgCl (2 equiv). Following a similar procedure, the yttrium- and scandium-bis(allyl) complexes, [(C(5)Me(4)-C(5)H(4)N)Ln(η(3)-C(3)H(5))(2)] (Ln=Y (3a), Sc (3b)), which also contained electron-withdrawing pyridyl-Cp ligands, were also obtained selectively. Deprotonation of the bulky pyridyl-Flu ligand (C(13)H(9)-C(5)H(4)N) by [Ln(CH(2)SiMe(3))(3)(thf)(2)] generated the rare-earth-metal-dialkyl complexes, [(η(3)-C(13)H(8)-C(5)H(4)N)Ln(CH(2)SiMe(3))(2)(thf)] (Ln=Y (4a), Sc (4b), Lu (4c)), in which an unusual asymmetric η(3)-allyl bonding mode of Flu moiety was observed. Switching to the bidentate yttrium-trisalkyl complex [Y(CH(2)C(6)H(4)-o-NMe(2))(3)], the same reaction conditions afforded the corresponding yttrium bis(aminobenzyl) complex [(η(3)-C(13)H(8)-C(5)H(4)N)Y(CH(2)C(6)H(4)-o-NMe(2))(2)] (5). Complexes 1-5 were fully characterized by (1)H and (13)C NMR and X-ray spectroscopy, and by elemental analysis. In the presence of both [Ph(3)C][B(C(6)F(5))(4)] and AliBu(3), the electron-donating aminophenyl-Cp-based complexes 1 and 2 did not show any activity towards styrene polymerization. In striking contrast, upon activation with [Ph(3)C][B(C(6)F(5))(4)] only, the electron-withdrawing pyridyl-Cp-based complexes 3, in particular scandium complex 3b, exhibited outstanding activitiy to give perfectly syndiotactic (rrrr >99%) polystyrene, whereas their bulky pyridyl-Flu analogues (4 and 5) in combination with [Ph(3)C][B(C(6)F(5))(4)] and AliBu(3) displayed much-lower activity to afford syndiotactic-enriched polystyrene.     

Allylic C-H bond activation and functionalization mediated by tris(oxazolinyl)borato rhodium(I) and iridium(I) compounds

Allylic C-H bond oxidative addition reactions, mediated by tris(oxazolinyl)borato rhodium(I) and iridium(I) species, provide the first step in a hydrocarbon functionalization sequence. The bond activation products To(M)MH(η(3)-C(8)H(13)) (M = Rh (1), Ir (2)), To(M)MH(η(3)-C(3)H(5)) (M = Rh (3), Ir (4)), and To(M)RhH(η(3)-C(3)H(4)Ph) (5) (To(M) = tris(4,4-dimethyl-2-oxazolinyl)phenylborate) are synthesized by reaction of Tl[To(M)] and the corresponding metal olefin chloride dimers. Characterization of these group 9 allyl hydride complexes includes (1)H-(15)N heteronuclear correlation NMR experiments that reveal through-metal magnetization transfer between metal hydride and the trans-coordinated oxazoline nitrogen. Furthermore, the oxazoline (15)N NMR chemical shifts are affected by the trans ligand, with the resonances for the group trans to hydride typically downfield of those trans to η(3)-allyl and tosylamide. These group 9 oxazolinylborate compounds have been studied to develop approaches for allylic functionalization. However, this possibility is generally limited by the tendency of the allyl hydride compounds to undergo olefin reductive elimination. Reductive elimination products are formed upon addition of ligands such as CO and CN(t)Bu. Also, To(M)RhH(η(3)-C(8)H(13)) and acetic acid react to give To(M)RhH(κ(2)-O(2)CMe) (8) and cyclooctene. In contrast, treatment of To(M)RhH(η(3)-C(3)H(5)) with TsN(3) (Ts = SO(2)C(6)H(4)Me) gives the complex To(M)Rh(η(3)-C(3)H(5))NHTs (10). Interestingly, the reaction of To(M)RhH(η(3)-C(8)H(13)) and TsN(3) yields To(M)Rh(NHTs)(H)OH(2) (11) and 1,3-cyclooctadiene viaβ-hydride elimination and Rh-H bond amination. Ligand-induced reductive elimination of To(M)Rh(η(3)-C(3)H(5))NHTs provides HN(CH(2)CH=CH(2))Ts; these steps combine to give a propene C-H activation/functionalization sequence.     

锰(III)5,10,15-三(五氟苯基)-Corrole配合物的DFT计算

在6-31G*水平上采用DFT(UB3LYP)方法对锰(III)5,10,15-三(五氟苯基)-corrole [(TPFC)MnIII]及其咪唑轴向配位加合物(TPFC)MnIII(Im)进行了几何结构全优化. 计算结果表明, 咪唑的配位作用不会改变其基态的高自旋(s=2)特性. (TPFC)MnIII与咪唑配位形成轴向加合物后, 其中心金属Mn原子偏离平面结构, 与corrole大环N4平均平面的距离达到0.02734 nm. NBO分析显示(TPFC)MnIII和(TPFC)MnIII(Im)中心金属锰的电子组态为(dxz)1(dyz)1(dz2)1(dx2-y2)1(dxy)0. (TPFC)MnIII(Im)前线分子轨道能级明显上升, 从其β-(LUMO+3)轨道可见咪唑配位N原子的py轨道与中心金属Mn原子dyz轨道形成了d-pπ轨道. TD-DFT计算发现, (TPFC)MnIII和(TPFC)MnIII(Im)电子光谱Q带的“四轨”特征比B 带明显; (TPFC)MnIII的CT带主要源自β-(HOMO-1)→β-(LUMO+5)和β-HOMO→β-(LUMO+4)的跃迁, (TPFC)MnIII(Im)的CT带则主要源自β-(HOMO-1)→β-(LUMO+3)和β-HOMO→β-(LUMO+4)的跃迁.     

Reaction of tin porphyrins with vicinal diols

Reactions of tin porphyrins with vicinal diols were investigated. Treatment of (TTP)Sn(CCPh)(2) or (TTP)Sn(NHtolyl)(2) with pinacol and 2,3-diphenylbutane-2,3-diol afforded diolato complexes (TTP)Sn[OC(Me)(2)C(Me)(2)O] (1) and (TTP)Sn[OC(Ph)(Me)C(Ph)(Me)O] (2), respectively. Both complexes underwent C-C cleavage reactions to give (TTP)Sn(II) and ketones. Reaction of (TTP)Sn(CCPh)(2) with 1 equivalent of o-catechol generated (TTP)Sn(CCPh)(OC(6)H(4)OH) (3), which subsequently transformed into (TTP)Sn(OC(6)H(4)O) (4). With excess catechol, disubstituted (TTP)Sn(OC(6)H(4)OH)(2) (5) was obtained. (TTP)Sn(CCPh)(OCHRCHROH) (R = H, 6; R = Ph, 8) and (TTP)Sn(OCHRCHROH)(2) (R = H, 7; R = Ph, 9) were obtained analogously by treatment of (TTP)Sn(CCPh)(2) with appropriate diols. In the presence of dioxygen, tin porphyrin complexes were found to promote the oxidative cleavage of vicinal diols and the oxidation of alpha-ketols to alpha-diketones. Possible reaction mechanisms involving diolato or enediolato intermediates are discussed. The molecular structure of (TTP)Sn(CCPh)(OC(6)H(4)OH) (3) was determined by X-ray crystallography.     

Reactivity of Mo(PMe3)6 towards benzothiophene and selenophenes: new pathways relevant to hydrodesulfurization

Mo(PMe(3))(6) cleaves a C-S bond of benzothiophene to give (kappa(2)-CHCHC(6)H(4)S)Mo(PMe(3))(4), which rapidly isomerizes to the olefin-thiophenolate and 1-metallacyclopropene-thiophenolate complexes, (kappa(1),eta(2)-CH(2)CHC(6)H(4)S)Mo(PMe(3))(3)(eta(2)-CH(2)PMe(2)) and (kappa(1),eta(2)-CH(2)CC(6)H(4)S)Mo(PMe(3))(4). The latter two molecules result from a series of hydrogen transfers and are differentiated according to whether the termini of the organic fragments coordinate as olefin or eta(2)-vinyl ligands, respectively. The reactions between Mo(PMe(3))(6) and selenophenes proceed differently from those of the corresponding thiophenes. For example, whereas Mo(PMe(3))(6) reacts with thiophene to give eta(5)-thiophene and butadiene-thiolate complexes, (eta(5)-C(4)H(4)S)Mo(PMe(3))(3) and (eta(5)-C(4)H(5)S)Mo(PMe(3))(2)(eta(2)-CH(2)PMe(2)), selenophene affords the metallacyclopentadiene complex [(kappa(2)-C(4)H(4))Mo(PMe(3))(3)(Se)](2)[Mo(PMe(3))(4)] in which the selenium has been completely abstracted from the selenophene moiety. Likewise, in addition to (kappa(1),eta(2)-CH(2)CC(6)H(4)Se)Mo(PMe(3))(4) and (kappa(1),eta(2)-CH(2)CHC(6)H(4)Se)Mo(PMe(3))(3)(eta(2)-CH(2)PMe(2)), which are counterparts of the species observed in the benzothiophene reaction, the reaction of Mo(PMe(3))(6) with benzoselenophene yields products resulting from C-C coupling, namely [kappa(2),eta(4)-Se(C(6)H(4))(CH)(4)(C(6)H(4))Se]Mo(PMe(3))(2) and [mu-Se(C(6)H(4))(CH)C(CH)(2)(C(6)H(4))](mu-Se)[Mo(PMe(3))(2)][Mo(PMe(3))(2)H].     

Visible spectrum of titanium dioxide

The electronic spectrum in the region 17?500 cm(-1) to 18?850 cm(-1) of a cold molecular beam of TiO(2) has been investigated using laser induced fluorescence (LIF) and mass-resolved resonance enhanced multi-photoionization (REMPI) spectroscopy. Bands at 18?412 cm(-1), 18?470 cm(-1) and 18?655 cm(-1) were recorded at a resolution of 35 MHz, rotationally analyzed, and assigned as the ?(1)B(2) (0,1,2) ←X[combining tilde](1)A(1) (0,0,0), ?(1)B(2) (1,0,0) ←X[combining tilde](1)A(1) (0,0,0) and ?(1)B(2) (1,1,0) ←X[combining tilde](1)A(1) (0,0,0) transitions. The dispersed fluorescence from the ?(1)B(2) (0,1,2) and ?(1)B(2) (1,0,0) levels were combined with previous results to produce an improved set of vibrational parameters for the X[combining tilde](1)A(1) state. The optical Stark effect in the ?(1)B(2) (0,1,2) ←X[combining tilde](1)A(1) (0,0,0) and ?(1)B(2) (1,0,0) ←X[combining tilde](1)A(1) (0,0,0) bands were recorded and combined with earlier results for ?(1)B(2) (1,1,0) ←X[combining tilde](1)A(1) (0,0,0) to determine the permanent electric dipole moment for these states. The origin and harmonic vibrational constants for the ?(1)B(2) state are determined to be: T(000) = 17?593(5) cm(-1), ω(1) = 876(3) cm(-1), ω(2) = 184(1) cm(-1), and ω(3) = 316(2) cm(-1). A normal coordinate analysis was performed and Franck-Condon factors calculated.     

Cyclic and linear polyferrocenes with silicon and tin as alternating bridges

The synthesis and characterization of ferrocene-based oligomers that contained two different elements (Si and Sn) as alternating bridges is described for the first time. The salt-metathesis reaction of R(2) Si[(C(5) H(4) )Fe(C(5) H(4) Li)](2) (R=Me, Et) with R'(2) SnCl(2) (R'=Me, nBu, tBu) afforded a mixture of oligomers (6(Me) SnMe(2), 6(Et) SnMe(2), 6(Me) SnnBu(2), 6(Et) SnnBu(2), 6(Me) SntBu(2), and 6(Et) SntBu(2)). These oligomers were characterized by (1) H, (13) C, (29) Si, and (119) Sn?NMR spectroscopy and by mass spectrometry. MS (MALDI-TOF) studies of 6(Et) SnMe(2) revealed the presence of linear (l) and cyclic (c) species that contained up to 20?ferrocene moieties. The molecular weights of the polymers were determined by gel-permeation chromatography (GPC) and by dynamic-light scattering (DLS). GPC analysis revealed average molecular weights of 2100-6300?Da with respect to polystyrene as a standard. DLS analysis yielded very similar results. Some compounds, c-(6(Me) SnMe(2) )(1), c-(6(Me) SntBu(2))(2), c-(6(Et) SnMe(2))(1), c-(6(Et) SntBu(2))(2), l-(6(Me) SnnBu(2) )(2), and l-(6(Me) SnnBu(2))(3), which contained up to six ferrocene moieties, were isolated in their pure form either by column chromatography or by crystallization. The Si- and Sn-bridged macrocycles that contained four ferrocene units (c-(6(Me) SntBu(2))(2) and c-(6(Et) SntBu(2))(2)) were structurally characterized by single-crystal X-ray analysis.     

The reaction of tertiary phosphines with (Ph2Se2I2)2--the influence of steric and electronic effects

The reaction of (Ph(2)Se(2)I(2))(2) with a wide variety of tertiary phosphines possessing different steric and electronic properties has been studied, leading in most cases to R(3)PSe(Ph)I adducts; [R(3)P = (p-CH(3)C(6)H(4))(3)P (1), (m-CH(3)C(6)H(4))(3)P (2), (o-OCH(3)C(6)H(4))(3)P (4), Ph(2)MeP (6), Me(2)PhP (7), Me(3)P (8), Cy(3)P (9)]. All of the products formed were characterised by elemental analysis, Raman and multinuclear NMR spectroscopy. Both steric and electronic factors are important in determining the structural motif (CT vs. ionic) observed in the solid-state. In general, highly basic phosphines result in a lengthening of the Se-I interaction, and a preference for an ionic structure. The reaction with (o-CH(3)C(6)H(4))(3)P does not yield a stable R(3)PSe(Ph)I adduct, and instead (o-CH(3)C(6)H(4))(3)PI(2) (3) is formed. The unusually long P-I bond, [2.5523(12) A], and short I-I bond, [3.0724(4) A], exhibited by is a result of the high steric requirements of this phosphine. The similarly bulky (o-SCH(3)C(6)H(4))(3)P yields a mixture of (o-SCH(3)C(6)H(4))(3)PSe(Ph)I (5a) and [(o-SCH(3)C(6)H(4))(3)PSePh]I(3) (5b). The crystal structures of (m-CH(3)C(6)H(4))(3)PSe(Ph)I, 2, (o-CH(3)C(6)H(4))(3)PI(2), 3, [(o-OCH(3)C(6)H(4))(3)PSePh]I.CH(2)Cl(2), 4, [(o-SCH(3)C(6)H(4))(3)PSePh]I(3), 5b, two pseudo-polymorphs of Ph(2)MePSe(Ph)I, 6a/6b, and [Me(3)PSe(Ph)I](2).CH(2)Cl(2), 8, are reported. The R(3)PSe(Ph)I adducts formed exhibit one of four types of behaviour. Type I products, (such as 2) are CT in the solid-state and display fluxionality in solution. Type II products (such as 6a/6b) lie close to the CT/ionic structural borderline, displaying long Se-I bonds, and are more appropriately classified as [R(3)PSePh] (acceptor)/I(-) (donor) CT complexes. Type II complexes ionise in solution to [R(3)PSePh]I. Type III products, such as 8, are ionic in solution, but frequently show cation-anion, or cation-solvent interactions in the solid-state, although these interactions are weak and the linear P-Se-I motif is lost. Type IV products (such as 4) are ionic and feature bulky phosphines. They display no short cation-anion interactions in the solid-state.     

Metallacycles of cadmium, mercury dicarboxylates

A series of linear coordination polymers, metallacycles of cadmium(II) and mercury(II) of flexible carboxylic acid ligands, RCH{3-CH(3)-,5-CH(3)-,6-(-OCH(2)CO(2)H)C(6)H(2)}(2), (when R = C(6)H(5), (H(2)L(1)); 2-NO(2)C(6)H(4)- (H(2)L(2)) and 3-NO(2)C(6)H(4)- (H(2)L(3))) are synthesized and characterized. [CdL(1) (py)(3)](n)·3nH(2)O (py = pyridine) is a linear coordination polymer, whereas [CdL(2)(py)(CH(3)OH)](2)·CH(3)OH is a dinuclear complex of cadmium with a Cd(2)O(2) type of core. The latter is obtained from reaction of cadmium(II) acetate with H(2)L(2) in methanol followed by reaction with pyridine. A similar reaction of cadmium(II) acetate with H(2)L(2) in dimethylformamide results in the formation of a cadmium metallacycle, namely [CdL(2) (py)(2)(H(2)O)](2)·H(2)O. The H(2)L(3) reacted with cadmium(II) acetate in the presence of pyridine to form a metallacycle [CdL(3)(py)(2)(H(2)O)](2)·3H(2)O. The ligand H(2)L(2) form mercury(II) metallacycle [HgL(2)(4-mepy)(2)](2) in the presence of 4-methylpyridine (4-mepy) and the ligand H(2)L(3) forms metallacycle [HgL(3)(3-mepy)(2)](2)·DMF in the presence of 3-methylpyridine (3-mepy). The potassium salts of H(2)L(1) and H(2)L(2) were found to be coordination polymers and these potassium coordination polymers were structurally characterized.     

Heterobimetallic Clusters of Copper(I) with Trithiotungstate and Trithiomolybdate. Synthesis and Characterization of the Octanuclear Clusters [Et(4)N](4)[M(4)Cu(4)S(12)O(4)] (M = Mo, W) and the Dodecanuclear Clusters [M(4)Cu(4)S(12)O(4)(CuTMEN)(4)] (M = Mo, W; TMEN = N,N,N',N'-Tetramethylethylenediamine)

Synthetic methods for [Et(4)N](4)[W(4)Cu(4)S(12)O(4)] (1), [Et(4)N](4)[Mo(4)Cu(4)S(12)O(4)] (2), [W(4)Cu(4)S(12)O(4)(CuTMEN)(4)] (3), and [Mo(4)Cu(4)S(12)O(4)(CuTMEN)(4)] (4) are described. [Et(4)N](2)[MS(4)], [Et(4)N](2)[MS(2)O(2)], Cu(NO(3))(2).3H(2)O, and KBH(4) (or Et(4)NBH(4)) were used as starting materials for the synthesis of 1 and 2. Compounds 3 and 4 were produced by reaction of [Et(4)N](2)[WOS(3)], Cu(NO(3))(2).3H(2)O, and TMEN and by reaction of [Me(4)N](2)[MO(2)O(2)S(8)], Cu(NO(3))(2).3H(2)O, and TMEN, respectively. Crystal structures of compounds 1-4 were determined. Compounds 1 and 2 crystallized in the monoclinic space group C2/c with a = 14.264(5) ?, b = 32.833(8) ?, c = 14.480(3) ?, beta = 118.66(2) degrees, V = 5950.8(5) ?(3), and Z = 4 for 1 and a = 14.288(5) ?, b = 32.937(10) ?, c = 14.490(3) ?, beta = 118.75(2) degrees, V = 5978.4(7) ?(3), and Z = 4 for 2. Compounds 3 and 4 crystallized in the trigonal space group P3(2)21 with a = 13.836(6) ?, c = 29.81(1) ?, V = 4942(4) ?(3), and Z = 3 for 3 and a = 13.756(9) ?, c = 29.80(2) ?, V = 4885(6) ?(3), and Z = 3 for 4. The cluster cores have approximate C(2v) symmetry. The anions of 1 and 2 may be viewed as consisting of two butterfly-type [CuMOS(3)Cu] fragments bridged by two [MOS(3)](2-) groups. Eight metal atoms in the anions are arranged in an approximate square configuration, with a Cu(4)M(4)S(12) ring structure. Compounds 3 and 4 can be considered to consist of one [M(4)Cu(4)S(12)O(4)](4-) (the anions of 1 and 2) unit capped by Cu(TMEN)(+) groups on each M atom; the Cu(TMEN)(+) groups extend alternately up and down around the Cu(4)M(4) square. The electronic spectra of the compounds are dominated by the internal transitions of the [MOS(3)](2-) moiety. (95)Mo NMR spectral data are investigated and compared with those of other compounds.     

Probing the structural and electronic properties of Ag(n)H(-) (n = 1-3) using photoelectron imaging and theoretical calculations

Structural and electronic properties of silver hydride cluster anions (Ag(n)H(-); n = 1-3) have been explored by combining the negative ion photoelectron imaging spectroscopy and theoretical calculations. The photoelectron spectrum of AgH(-) exhibits transitions from AgH(- 2)Σ(+) to AgH (1)Σ(+) and AgH (3)Σ(+), with the electron affinity (EA) 0.57(3) eV. For Ag(2)H(-), the only observed transition is from Ag(2)H(-) (C(∞v)) (1)Σ(+) to Ag(2)H (C(2v)) (2)A(') and the electron affinity is 2.56(5) eV. Two obvious electron bands are observed in photoelectron imaging of Ag(3)H(-), which are assigned to the transitions from Ag(3)H(-) (C(2v)-T, which means C(2v) geometry with top site hydrogen) (2)B(2) to Ag(3)H (C(2v)-T) (1)A(1) and Ag(3)H (C(2v)-T) (3)B(2). The electron affinity is determined to be 1.61(9) eV. The Ag-H stretching modes in the ground states of AgH and Ag(2)H are experimentally resolved and their frequencies are measured to be 1710(80) and 1650(100) cm(-1), respectively. Aside from the above EAs and the vibrational frequencies, the vertical detachment energies to all ground states and some excited states of Ag(n)H (n = 1-3) are also obtained. Theoretical calculations reproduce the experimental energies quite well, and the results are used to assign the geometries and electronic states for all related species.     

Ionic liquids and deep eutectic mixtures as new solvents for the synthesis of vanadium fluorides and oxyfluorides

An exploratory study of the synthesis of vanadium (oxy)fluorides (VOFs) using ionic liquids (ILs) and deep eutectic mixtures (DESs) as a solvent yielded 10 different materials. The previously reported chain type: (NH(4))(2)VF(5) (1), (NH(4))(2)VOF(4) (2), NH(4)VO(3) (3) and (H(2)NH(2)(CH(2))(2)NH(2))VF(5) (9) have been successfully produced for the first time using ILs as the reaction media. The monomeric (HNH(2)CH(3))(2)VOF(4)(H(2)O) (4), the dimer (HNH(2)CH(3))(4)V(2)O(2)F(8) (5) and the 1D chains (HNH(2)CH(3))(2)VF(5) (6), (H(2)O)(2)VF(3) (7), α-(H(2)NH(2)(CH(2))(2)NH(2))VOF(4) (8) and β-(H(2)NH(2)(CH(2))(2)NH(2))VOF(4) (10) are novel materials. Template control has also been achieved by the selective choice of ILs or the appropriate deep eutectic mixture, where the expected template is delivered to the reaction by the partial breakdown of the urea derivative portion of the DES.     

Unimolecular reactions including ClF interchange of vibrationally excited CF2ClCHFCH2CH3 and CF2ClCHFCD2CD3

Vibrationally excited CF(2)ClCHFC(2)H(5)(CF(2)ClCHFC(2)D(5)) molecules were prepared in the gas phase at 300 K with approximately 93 kcal mol(-1) of energy by recombination of CF(2)ClCHF and C(2)H(5) or C(2)D(5) radicals. Three unimolecular reactions were observed. 1,2-ClF interchange converts CF(2)ClCHFC(2)H(5)(CF(2)ClCHFC(2)D(5)) into CF(3)CHClC(2)H(5)(CF(3)CHClC(2)D(5)), and subsequent 2,3-ClH (ClD) elimination gives CF(3)CH=CHCH(3) (CF(3)CH=CDCD(3)). 2,3-FH(FD) elimination gives cis- and trans-CF(2)ClCH=CHCH(3) (CF(2)ClCH=CDCD(3)), and 1,2-ClH elimination gives CF(2)=CFCH(2)CH(3) (CF(2)=CFCD(2)CD(3)). The experimental rate constants for CF(2)ClCHFC(2)H(5) (CF(2)ClCHFC(2)D(5)) were 1.3 x 10(4) (0.63 x 10(4)) s(-1) for 1,2-FCl interchange and 2.1 x 10(4) (0.61 x 10(4)) s(-1) with a trans/cis ratio of 3.7 for 2,3-FH(FD) elimination. The 1,2-ClH process was the least important with a branching fraction of only 0.08 +/- 0.04. The rate constants for 2,3-ClH (ClD) elimination from CF(3)CHClC(2)H(5) (CF(3)CHClC(2)D(5)) were 1.8 x 10(6) (0.49 x 10(6)) s(-1) with a trans/cis ratio of 2.4. Density functional theory was used to compute vibrational frequencies and structures needed to obtain rate constants from RRKM theory. Matching theoretical and experimental rate constants provides estimates of the threshold energies, E0, for the three reaction pathways; 1,2-FCl interchange has the lowest E0. The unimolecular reactions of CF(2)ClCHFC(2)H(5) are compared to those of CF(2)ClCHFCH(3). Both of these systems are compared to CH(3)CHFC(2)H(5) to illustrate the influence of a CF(2)Cl group on the E0 for FH elimination.