Nucleophilic Addition to (η3-Allyl)Fe(CO)4 Cations with Functionalized Zinc-Copper Reagents RCu(Znl)CN

Regioselectivity of the addition of the highly functionalized zinc-copper reagents to (η³-allyl)Fe(CO)₄ cationic salts was studied. For 1,1-disubstituted allyl cation 1, the zinc-copper reagents added predominantly at the unsubstituted terminus. For 1,1,2-trisubstituted allyl cation 2, reactive zinc-copper reagents attacked mainly at the unsubstituted terminus while less reactive zinc-copper reagents added to a coordinated CO ligand. For 1,1,3-trisubstituted allyl cation 3, the addition occurred at both the less substituted allyl terminus and a coordinated CO ligand.     

Kristall- und molekülstruktur von η3-allyl-tricarbonyl-ethylenbis(diphenylphosphin)vanadium(0), η3-C3H5V(CO)3(Ph2PCH2CH2PPh2)

A single crystal X-ray structure investigation of η³3-allyltricarbonylethylenebis(diphenylphosphine)vanadium(0) has been carried out (R = 0.04, 3061 significant reflexions). The orthorhombic unit cell (space group Pbcn) contains 8 molecules. Considering the allyl group as a monodentate ligand, the central V atom is coordinated pseudooctahedrally with the CO groups in meridional positions. As expected the distances from V to the terminal C atoms of the allyl group are significantly greater than to the central C atom. The C and H atoms of the allyl group are not coplanar as shown by computation of least-squares planes.     

Synthesis and structural characterization of (μ-H)2RU3(CO)9(μ3-η-C8H12) and (μ-H)RU3(CO)9(μ3-η-C12H19)

The reaction between Ru₃(CO)₁₂ and a cyclic olefin (cis-cyclooctene or trans-cyclododecene) at 100 °C for several hours gives the title compounds (μ-H)₂RU₃(CO)₉(μ₃-η²-C₈H₁₂) (1), and (μ-H)RU₃(CO)₉(μ₃-η³-C₁₂H₁₉) (2), both of which have been characterized by X-ray diffraction studies, IR and NMR spectral measurements and elemental analysis. The prolonged reaction between Ru₃(CO)₁₂ and cis-cyclooctene gives compound HRu₃(CO)₉(C₈H₁₁) (3). Compound 3 has been characterized with IR and NMR spectral analyses. In 1 the cyclooctene ring is linked via a μ₃-η²-alkyne type of bonding to the face of the Ru₃ cluster. It is formally σ-bonded to two of the three Ru atoms and π-bonded to the third Ru. The two hydrides in 1 are bridging Ru---Ru bonds. In 2 the cyclododecene ring is bonded to the Ru₃ face via the μ₃-η³-CCHC linkage. There are two formal σ-bonds from the allyl part to the hydrido-bridged Ru atoms and the η³-allyl linkage to the third Ru atom.     

A comparative theoretical study on CO insertion into Rh–C bond

A DFT study on CO insertion into Rh–C(alkylethyl, ethenyl, 2-propenyl, trans-propenyl, cis-propenyl, and allyl) bonds were carried out comprehensively. All structures were optimized completely and the mechanism of the CO insertion was discussed in detail. The present results indicated that except for the CO insertion into Rh–C(allyl), other CO insertions were feasible from the thermodynamics point of view. The CO insertion into Rh–C(cis-propenyl) was the easiest process with 24.42 kJ/mol of the lowest activation free energy and the most difficult was the CO insertion into Rh–C(allyl). Also, entropy played a critical role in the CO insertion except for the CO insertion into Rh–C(ethenyl).     

The unusual role of CO transfer in molybdenum-catalyzed asymmetric alkylations

Spectroscopic and crystallographic studies were undertaken to gain insight into the mechanism of the highly regio- and enantioselective allylic aklylation reaction catalyzed by molybdenum. The chiral ligand (L*) consisting of the mixed benzamide/picolinamide of (S,S,)-trans-1,2-diaminocyclohexane reacts with a typical Mo precatalyst, (norbornadiene)Mo(CO)4, to give a neutral complex L*Mo(CO)4 in which the ligand binds to the metal in a bidentate fashion through the pyridine and adjacent amide group. Reaction of this complex with the methyl carbonate of cinnamyl alcohol gives the corresponding pi-allyl complex L*(CO)2Mo(eta3-CH2=CH-CHPh). NMR and X-ray crystallographic characterization of this complex reveal the ligand binds in a facially capping tridentate fashion via the pyridine nitrogen, the nitrogen of the adjacent amide group, which has now been deprotonated, and the carbonyl oxygen of the remote amide. Surprisingly, the face of the allyl group open to attack with nucleophiles is that which would lead to the sense of stereochemistry opposite to that which is observed in catalytic reactions. Furthermore, the allyl complex in its isolated form is unreactive toward sodium dimethyl malonate. However, in the presence of a source of carbon monoxide (either Mo(CO)6 or gaseous CO), the allyl complex reacts with malonate to give the typically observed branched alkylated product in high yield and enantiomeric excess. The metal-containing product of this reaction is the molybdate complex [L*Mo(CO)4]-Na+. Reaction of the molybdate complex with linear or branched allylic carbonates regenerates the allyl complex, thus closing the catalytic cycle. Both the allyl complex and the molybdate complex are the only metal-containing species observed by NMR in typical catalytic reactions and thus appear to be catalyst resting states. Turnover of the catalytic cycle therefore involves shuttling of carbon monoxide between the two catalyst resting states. Coordination of CO appears to be necessary to activate the allyl complex toward nucleophilic attack, in effect stabilizing the molybdenum fragment as a leaving group.     

Carbonyl (η3-allyl) anions of molybdenum and tungsten

Anionic complexes of the type [M(CO)₂(diket)(η³-allyl)Cl]^? (where M is Mo or W and diket is a β-diketonate group) are readily prepared by the addition of allyl chloride to [M(CO)₄(diket)]^? anions. NMR measurements indicate an equilibrium between two conformers due to rotation of the allyl groups. [M(CO)₅(OC(=O)R)]^? anions also react with allyl chloride to form η³-allyl complex anions. Some structural aspects of both the diketonate and carboxylate derivatives are discussed.     

The photochemistry of (η-2-R-C3H4)Fe(CO)(NO)(X) (R = H or Cl; X = CO or PPh3) in room temperature solution or frozen gas matrixes

A photochemical study of allyl iron complexes of the type, (η³-2-R-C₃H₄)Fe(CO)(NO)(X) (R = H or Cl; X = CO or PPh₃) is presented. These compounds were studied in solid matrixes at 20 K, and at room temperature, by a combination of laser flash at 355 nm and steady-state photolysis. The predominant photochemical process for these compounds is loss of a CO ligand. In addition, exhaustive irradiation of (η³-2-R-C₃H₄)Fe(CO)(NO)(PPh₃) with λ_exc > 300 nm provided evidence for a haptotropic shift of the allyl group from η³ to η¹ coordination.     

Molybdenum- and tungsten(II) monometallic 3-(2-pyridyl)pyrazole and bimetallic 3-(2-pyridyl)pyrazolate complexes

Molybdenum and tungsten complexes containing the pypzH (3-(2-pyridyl)pyrazole) ligand as a chelating bidentate are prepared: [Mo(CO)(4)(pypzH)], cis-[MoBr(η(3)-allyl)(CO)(2)(pypzH)], cis-[MoCl(η(3)-methallyl)(CO)(2)(pypzH)], [MI(2)(CO)(3)(pypzH)] (M = Mo, W) from [Mo(CO)(4)(NBD)] or the adequate bis(acetonitrile) complexes. The deprotonation of the molybdenum allyl or methallyl complexes affords the bimetallic complexes [cis-{Mo(η(3)-allyl)(CO)(2)(μ(2)-pypz)}](2) or [cis-{Mo(η(3)-methallyl)(CO)(2)(μ(2)-pypz)}](2) (μ(2)-pypz = μ(2)-3-(2-pyridyl-κ(1)N)pyrazolate-2κ(1)N). The allyl complex was subjected to an electrochemical study, which shows a marked connection between both metallic centres through the bridging pyridylpyrazolates.     

Insertion of CO2 into a palladium allyl bond and a Pd(II) catalysed carboxylation of allyl stannanes

The complex 2,6-bis[(di-t-butylphosphino)methyl]phenyl allyl palladium (PCP(tBu)Pd-allyl, 3) reacts with CO(2) in a very fast insertion reaction to give the corresponding butenoate complex. The reaction is thought to occur via a cyclic six-membered transition state (7), where the gamma-carbon of the allyl group is linked up with the CO(2)-carbon. A group of related PCP complexes were investigated as catalysts for the carboxylation of tributyl(allyl)stannane. A catalytic cycle is proposed for this reaction where the rate determining step is the transmetallation between tin and palladium. The carboxylation reaction is faster using less sterically crowded catalysts whereas the electron richness of the palladium complexes seems less important for reactivity. Thus, there was no apparent difference in reactivity between 2,6-bis[(di-phenylphosphino)methyl]phenyl palladium triflouroacetate (13) and resorcinolbis(diphenyl)phosphinite palladium triflouroacetate (10). Both of these complexes give high turnovers for the carboxylation of tributyl(allyl)stannane (80% in 16 h using a ca. 5% catalyst loading and 4 atm CO(2) pressure). On the other hand complex 3 was inactive in the catalytic carboxylation reaction.     

Effect of M(CO)3 (M = Cr, Mn+) on aromatic C-Cl BDE in (eta6-ArCl)M(CO)3 complexes

The coordination of Cr(CO)3 to chlorobenzenes significantly reduces the C-Cl bond dissociation energy. Treatment of chloroarene-Cr(CO)3 complexes with SmI2/HMPA at room temperature led to complete dechlorination. Reaction of o-allyloxychlorobenzene-Cr(CO)3 complexes with SmI2 at room temperature resulted in the corresponding dechlorinative cyclization products in good to excellent yields. Competition experiments indicated the following relative reactivities of dehalogenation by SmI2: PhI/PhCl-Cr(CO)3/PhBr/PhCl = 50:1:0.3:<0.001. On the other hand, the coordination of Mn(CO)3(+) to chlorobenzene showed a much smaller activation effect. Density functional theory calculations revealed that the spin delocalization effect of the metal center plays an important role in the C-Cl bond activation.     

Mo4(η3‐allyl)4Cl2(OH)2(CO)8: the first cubane‐type Mo2+ organometallic complex with μ3‐OH and μ3‐Cl bridges

The reaction between fluorenyllithium and Mo(η³‐C₃H₅)Cl(NCMe)₂(CO)₂ led to the isolation of di‐μ₃‐chlorido‐di‐μ₃‐hydroxido‐tetrakis[(η³‐allyl)dicarbonylmolybdenum(II)]–9‐fluorenone–tetrahydrofuran (1/1/1), [Mo₄(C₃H₅)₄Cl₂(OH)₂(CO)₈]·C₄H₈O·C₁₃H₈O. The tetrametallic Mo₄ unit constitutes the first example of a complex containing simultaneously two μ₃‐OH groups and two μ₃‐Cl anions capping the metallic trigonal prism. The four crystallographically independent Mo²⁺ centres exhibit distorted octahedral geometry with the η³‐allyl groups being trans‐coordinated to a μ₃‐OH group and the carbonyl groups occupying the equatorial plane. Space‐filling tetrahydrofuran and 9‐fluorenone molecules are engaged in strong O—H...O hydrogen‐bonding interactions with Mo₄(η³‐allyl)₄Cl₂(OH)₂(CO)₈ complexes.     

Pd-catalyzed reaction of allyl carbonate with polyols: the role of CO2 in transesterification versus etherification of glycerol

An intermolecular Pd/PPh(3)-catalyzed transesterification of diallyl carbonate with glycerol to generate glycerol carbonate has been developed. Analysis of the reaction kinetics in THF indicates a first-order dependence on Pd and diallyl carbonate, that the Pd bears two phosphines during the turnover limiting event, and that increasing the glycerol concentration inhibits reaction, possibly via change in the polarity of the medium. (13)C isotopic labeling studies demonstrate that the Pd-catalyzed transesterification requires at least one allyl carbonate moiety and that there is rapid equilibrium of the allyl carbonate with CO(2) in solution, even when present only at low concentrations. A mechanism that is consistent with these results involves oxidative addition of the allyl carbonate to Pd followed by reversible decarboxylation, with the intermediate η(1)- and η(3)-allyl Pd alkoxides mediating direct and indirect transesterification reactions with the glycerol. Using this model, successful simulations of the kinetics of reactions conducted under atmospheres of N(2) or CO(2) could be achieved, including switching in selectivity between etherification and transesterification in the early stages of reaction. Reactions with the higher polyols threitol and erythritol are also efficient, generating the terminal (1,2) monocarbonates with high selectivity.     

Palladium(I)-bridging allyl dimers for the catalytic functionalization of CO2

In general, the chemistry of both η(1)-allyl and η(3)-allyl Pd complexes is extremely well understood; η(1)-allyls are nucleophilic and react with electrophiles, whereas η(3)-allyls are electrophilic and react with nucleophiles. In contrast, relatively little is known about the chemistry of metal complexes with bridging allyl ligands. In this work, we describe a more efficient synthetic methodology for the preparation of Pd(I)-bridging allyl dimers and report the first studies of their stoichiometric reactivity. Furthermore, we show that these compounds can activate CO(2) and that an N-heterocyclic carbene-supported dimer is one of the most active and stable catalysts reported to date for the carboxylation of allylstannanes and allylboranes with CO(2).     

Crystal and molecular structure of (η3-allyl)carbonylchlorobis(dimethylphenylphosphine)- iridium(III) hexafluorophosphate, [Ir(η3-C3H5)Cl(CO)(P(CH3)2(C6H5))2][PF6

The structure of (η³-allyl)carbonylchlorobis(dimethylphenylphosphine)-iridium(III) hexafluorophosphate, [Ir(η³-C₃H₅)Cl(CO)(P(CH₃)₂(C₆H₅))₂][PF₆], has been determined from three-dimensional X-ray data to add support for a proposed mechanism of the oxidative addition of allyl halides to IrX(CO)(PR₃)₂ (X = halide). The compound crystallizes in space group C⁵_2h-P2₁/c with four formula units in a cell of dimensions a = 11.027(1), b = 12.230(2), c = 19.447(5) Å, and β = 103.16(2)⁰. Least-squares refinement of the structure has led to a value of the conventional R index (on F) of 0.066 for the 3018 independent reflections having F²₀>3—(F²₀). The crystal structure consists of discrete, monomericions. The hexafluorophosphate anion is disordered. The coordination geometry around the iridium atom may be described as octahedral, with the chloro ligand trans to the carbonyl group and each phosphorus atom trans to a terminal carbon of the allyl group. Structural parameters: Ir—P = 2.366(4), 2.347(3);Ir—Cl = 2.389(3); Ir—C(allyl) = 2.28(1), 2.24(1),2.25(1); Ir—C (carbonyl) = 1.85(1) Å; P—Ir—P = 105.7(1); C(terminal)—Ir—C(terminal) = 66.2(8); C—C—C = 125(2)^o. The allyl group makes an angle of 126^o with the P—Ir—P plane. Correlations between geometric structure and number of d electrons are noted among several M—C₃H₅-complexes, and are interpreted in the light of theoretical models of the M—C₃H₅- bond.     

Theoretical study on the reaction mechanism of(CH_3)_3CO+CO

The global environment pollution includes pho-tochemical smog, acid rain and stratospheric ozonedepletion. The short-lived species/radicals in atmos-phere are closely related to these phenomena. Theshort-lived species/radicals bring the photochemicalsmog,…     

Organopolysilane oligomers bearing transition-metal moieties: Synthesis, reactivities and molecular structure of [η-Me3SiMe2SiC5H4(CO)Fe(CO)2Fe(CO)-η-C5H4SiMe2SiME3]

Reaction of Me₃SiMe₂SiC₅H₅ (4), prepared from Me₃SiMe₂SiCl and C₅H₅Na, with Fe(CO)₅ in refluxing xylene afforded the title compound (3). The silicon-silicon bond in 3 is exceptionally stable in refluxing xylene and also in succeeding reactions to prepare a series of its derivatives. Thus, 3 reacted with I₂ in either chloroform or benzene, giving [η⁵-Me₃SiMe₂SiC₅H₄Fe(CO)₂I] (6). Compound 3 was reduced by sodium amalgam and reacted subsequently with CH₃I, PhCH₂Cl, CH₃COCl, PhCOCl, Cy₃SnCl (Cy = cyclohexyl) and Ph₃SnCl, producing [η⁵-Me₃SiMe₂SiC₅H₄Fe(CO)₂R][7 : R = CH₃ (a), PhCH₂ (b), CH₃CO (c), PhCO (d), Cy₃Sn (e) and Ph₃Sn (f), respectively]. The molecular structure of 3 has been determined by X-ray diffraction crystallography. It was found that 3 has a trans-configuration with a symmetrical centre located at the middle of the Fe---Fe bond. It is abnormal that the conformation of the disilane part around the Si---Si bond is almost eclipsed rather than staggered.     

Multiple ligand transfer reaction between [CpRu(L)(AN)2][PF6] (L=AN, CO, P(OMe)3; AN=acetonitrile) and CpFe(CO)L′X (L′=CO, PMe3, PMe2Ph, PMePh2, PPh3, P(OPh)3; X=Cl, Br, I)

Treatment of ruthenium complexes [CpRu(AN)₃][PF₆] (1a) (AN=acetonitrile) with iron complexes CpFe(CO)₂X (2a–2c) (X=Cl, Br, I) and CpFe(CO)L′X (6a–6g) (L′=PMe₃, PMe₂Ph, PMePh₂, PPh₃, P(OPh)₃; X=Cl, Br, I) in refluxing CH₂Cl₂ for 3 h results in a triple ligand transfer reaction from iron to ruthenium to give stable ruthenium complexes CpRu(CO)₂X (3a–3c) (X=Cl, Br, I) and CpRu(CO)L′X (7a–7g) (L′=PMe₃, PMe₂Ph, PMePh₂, PPh₃, P(OPh)₃; X=Br, I), respectively. Similar reaction of [CpRu(L)(AN)₂][PF₆] (1b: L=CO, 1c: P(OMe)₃) causes double ligand transfer to yield complexes 3a–3c and 7a–7h. Halide on iron, CO on iron or ruthenium, and two acetonitrile ligands on ruthenium are essential for the present ligand transfer reaction. The dinuclear ruthenium complex 11a [CpRu(CO)(μ-I)]₂ was isolated from the reaction of 1a with 6a at 0°C. Complex 11a slowly decomposes in CH₂Cl₂ at room temperature to give 3a, and transforms into 7a by the reaction with PMe₃.     

Syntheses of gold-manganese and gold-rhenium clusters, [(Ph3PAu)3M(CO)4] and [(Ph3PAu)4M(CO)4] (M = Mn, Re), and the crystal structure of [(Ph3PAu)4Mn(CO)4]BF4

The specific additions of one, three or four Ph₃PAu groups to [M(CO)₅]⁻ (M=Mn, Re) are described. Thus [M(CO)₅] ⁻ in THF reacts with [(Ph₃PAu)₃O]BF₄ to give [(Ph₃PAu)₄Mn(CO)₄]BF₄. An X-ray crystal structure of the M = Mn example shows the cation to have a trigonal bipyramidal Au₄Mn core with the Mn in an equatorial site. The previously known neutral (Ph₃PAu)₃M(CO)₄ clusters are formed by addition of two Ph₃PAu groups, using the mixed reagent [(Ph₃PAu) ₃O]BF₄/[ppn][Co(CO)₄], to Ph₃PAuM(CO)₅, which itself is readily prepared from [M(CO)₅]⁻ and Ph₃PAuCl.     

Synthesis and characterisation of HRuRh3(CO)12. Crystal structures of HRuRh3(CO)12, HRuRh3(CO)10(PPh3)2 and HRuCo3(CO)10(PPh3)2

A new ruthenium-rhodium mixed-metal cluster HRuRh₃(CO)₁₂ and its derivatives HRuRh₃(CO)₁₀(PPh₃)₂ and HRuCo₃(CO)₁₀(PPh₃)₂ have been synthesized and characterized. The following crystal and molecular structures are reported: HRuRh₃(CO)₁₂: monoclinic, space group P2₁/c, a 9.230(4), b 11.790(5), c 17.124(9) Å, β 91.29(4)°, Z = 4; HRuRh₃(CO)₁₀(PPh₃)₂·C₆H₁₄: triclinic, space group P$\text{1}$, a 11.777(2), b 14.079(2), c 17.010(2) Å, α 86.99(1), β 76.91(1), γ 72.49(1)°, Z = 2; HRuCo₃(CO)₁₀(PPh₃)₂·CH₂Cl₂: triclinic, space group P$\text{1}$, a 11.577(7), b 13.729(7), c 16.777(10) Å, α 81.39(4), β 77.84(5), γ 65.56°, Z = 2. The reaction between Rh(CO)₄^? and (Ru(CO)₃Cl₂)₂ tetrahydrofuran followed by acid treatment yields HRuRh₃(CO)₁₂ in high yield. Its structural analysis was complicated by a 80–20% packing disorder. More detailed structural data were obtained from the fully ordered structure of HRuRh₃(CO)₁₀(PPh₃)₂, which is closely related to HRuCo₃(CO)₁₀(PPh₃)₂ and HFeCo₃(CO)₁₀(PPh₃)₂. The phosphines are axially coordinated.     

超薄铝/碳酸锂修饰氧化铟锡阴极制备蓝色磷光反转底发光有机发光二极管

在氧化铟锡（ITO）阴极上依次蒸镀2 nm铝和2 nm碳酸锂（Li2CO3）薄膜作为电子注入层,成功制备出器件结构为ITO/Al/Li2CO3/SPPO13/SPPO13∶FIrpic/TCTA/MoO3/Al(SPPO13：2,7-双（二苯基磷）-9,9′-螺二[芴];FIrpic：双(4,6-二氟苯基吡啶-N,C2)吡啶甲酰合铱;TCTA：4,4′,4″-三(咔唑-9-基)三苯胺)的蓝色磷光反转底发光有机发光二极管（IBOLED）。 结果表明,Al/Li2CO3作为电子注入层可以有效降低ITO与有机材料之间的电子注入势垒,蓝色磷光IBOLED的起亮电压由11 V降至4.2 V,器件的发光效率也得到有效提高。 蓝光磷光IBOLED的最大电流效率与功率效率分别达到了28.2 cd/A和19.6 lm/W,制备出的反转结构器件性能可与传统正置结构比美,说明Al/Li2CO3可以作为反转有机发光二极管优良的电子注入层。