Comparison of the bis(ferrocenylethynyl)phenylmethylium cation with bis(ferrocenylethenyl)methylium analogues

Several new ferrocenylethynyl derivatives, (FcCC)₂CHOH, (FcCC)₂CH₂, (FcCC)₂CPhOH have been synthesised from ethynylferrocene. Attempts to synthesise the corresponding bis(ferrocenylethynyl)-stabilised carbocations by hydroxyl or hydride abstraction from the bridging group was unsuccessful for (FcCC)₂CHOH and (FcCC)₂CH₂, respectively. In the case of (FcCC)₂CPhOH, the [(FcCC)₂CPh]⁺ cation could be observed by ¹H and ¹³C NMR, and by UV-Vis-NIR spectroscopy, but was too unstable for isolation or prolonged study in solution. The UV-Vis-NIR spectrum of [(FcCC)₂CPh]⁺ is compared to that of the considerably more stable cations, [Fc(CHCH)₂CH]⁺ and [(FcCHCH)₂CPh]⁺.     

Cationic iridium-BINAP complex-catalyzed addition of aryl ketones to alkynes and alkenes via directed C-H bond cleavage

Cationic Ir complex ([Ir(cod)₂]BF₄ + BINAP) catalyzed the addition of ortho-C-H bonds in aryl ketones to alkynes, which gave alkenylated products in good to high yield. Styrene derivatives were good substrates, and the enantioselective addition to norbornene was also described.     

Preparation, structure and some chemistry of FcCCCCCCRu(dppe)Cp

The synthesis of Fc(CC)₃Ru(dppe)Cp (2) from Fc(CC)₃SiMe₃ and RuCl(dppe)Cp is described, together with its reactions with tcne to give the tetracyano-dienyl FcCCCC{C[C(CN)₂]}₂Ru(dppe)Cp (3) and -cyclobutenyl FcCCCC{CCC(CN)₂C(CN)₂}Ru(dppe)Cp (4), with Co₂(μ-dppm)_n(CO)_8−2n (n = 0, 1) to give FcC₂{Co₂(CO)₆}C₂{Co₂(CO)₆}CCRu(dppe)Cp (5) and FcCCCCC₂{Co₂(μ-dppm)(CO)₄}Ru(dppe)Cp (6), respectively, and with Os₃(CO)₁₀(NCMe)₂ to give Os₃{μ₃-C₂CCCC[Ru(dppe)Cp]}(CO)₁₀ (7). On standing in solution, the latter isomerises to the cyclo-metallated derivative Os₃(μ-H){μ₃-C[Ru(dppe)Cp]CCC[(η-C₅H₃)FeCp]}(CO)₈ (8). X-ray structural determinations of 1, 2, 6 and 7 are reported.     

DFT-assisted design and evaluation of bifunctional copper(I) catalysts for the direct intermolecular addition of aldehydes and ketones to alkynes

Bifunctional catalysts containing discrete metal pi-acid and amine sites were designed and investigated for the direct intermolecular addition of aldehydes and ketones to unactivated alkynes. Copper(I)-based catalysts were prioritized based on intramolecular (Conia-ene type) reactions, and complexes were designed with tridentate ligands and potentially hemilabile heterocyclic spacers. The structures of the designed catalysts were computed using density functional theory (DFT), and the relative energies of putative catalytic intermediates were estimated and used to prioritize catalyst designs. Novel bifunctional precatalysts containing a thiazole spacer were synthesized via a 9-step sequence and combined with transition metals before screening for the direct addition of aldehydes and ketones to several internal and terminal alkynes. Despite the lack of desired intermolecular reactions, DFT calculations of putative catalyst intermediates appears to be a promising strategy for the design and prioritization of bifunctional catalysts for CC bond formation.     

Synthesis and characterisation of new platinum ethynyl dimers and polymers with pendant ferrocenyl groups

The square-planar platinum(II) complex trans-[(Ph₂FcP)₂PtCl₂] (1) (Fc=ferrocenyl), that is a metal-containing polymer precursor, has been synthesised and its single crystal structure determined. Using 1, new ferrocene-containing platinum ethynyl dimers trans-[(Ph₂FcP)₂Pt(CCR)₂] {R=SiMe₃ (2), C₆H₅ (3) and C₆H₄-p-NO₂ (4)} and a polymer [(Ph₂FcP)₂Pt(CCC₆H₂-p-(OC₈H₁₇)₂CC)]_n (5) have been formed by the reaction of the metal precursor with the appropriate mono- and bis-ethynyl ligands. Single crystal X-ray studies of 4 have shown it to exist as two different polymorphic forms, both having trans-geometry with respect to the ferrocenyl phosphines and ethynyl ligands. GPC measurements on the polymer show a high degree of polymerisation with an average molecular weight of ca. 88?000.     

Study of the reactivity of palladacycles containing [C(sp, ferrocene),N,S] or [C(sp),N,S] terdentate ligands with symmetric alkynes

The study of the reactivity of the cyclopalladated complex [Pd{[(η⁵-C₅H₃)-CHN-(C₆H₄-2-SMe)]Fe(η⁵-C₅H₅)}Cl] (1c) with the alkynes R¹-CC-R¹ (with R¹ = CO₂Me, Ph or Et) is reported.Compound 1c reacts with the equimolar amount of MeO₂C-CC-CO₂Me in refluxing CH₂Cl₂ to give [Pd{[(MeO₂C-CC-CO₂Me)(η⁵-C₅H₃)-CHN-(C₆H₄-2-SMe)]Fe(η⁵-C₅H₅)}Cl] (2c), which arises from the monoinsertion of the alkyne into the σ[Pd-C(sp², ferrocene)] bond.However, when the reaction was performed using Ph-CC-Ph or Et-CC-Et no evidence of the insertion of these alkynes into the σ[Pd-C(sp², ferrocene)] bond was detected.In contrast with these results, when 1c was treated with the Tl[BF₄] followed by the removal of the TlCl formed and the subsequent addition of MeO₂C-CC-CO₂Me the reaction gave 2c and [Pd{[(MeO₂C-CC-CO₂Me)₂(η⁵-C₅H₃)-CHN-(C₆H₄-2-SMe)]Fe(η⁵-C₅H₅)}][BF₄] (3c); but when the alkyne was R¹-CC-R¹ (with R¹ = Ph or Et), the ionic palladacycles [Pd{[(R¹-CC-R¹)₂(η⁵-C₅H₃)-CHN-(C₆H₄-2-SMe)]Fe(η⁵-C₅H₅)}][BF₄] · CH₂Cl₂ [with R¹ = Ph (5c) or Et (6c)] were isolated. In compounds 3c, 5c and 6c, the mode of binding of the butadienyl unit is η³. The reactions of 2c, 3c, 5c and 6c with PPh₃ are also reported. The results obtained from these studies reveal that the σ(Pd-S) bond in 2c is more prone to cleave than in 4c-6c. X-ray crystal structures of 2c, 5c and [Pd{[(MeO₂C-CC-CO₂Me)(η⁵-C₅H₃)-CHN-(C₆H₄-2-SMe)]Fe(η⁵-C₅H₅)}Cl(PPh₃)] (7c), are also described. Compound 7c arises from 2c by cleavage of the Pd-S bond and the incorporation of a PPh₃ in the coordination sphere of the palladium. A parallel study focused on the reactions of [Pd{[2-CH₂-4,6-Me₂-C₆H₂]-CHN-(C₆H₄-2-SMe)}Cl] (1d) (with a [Csp³,N,S]⁻ terdentate group) with the three alkynes reveals that the σPd-C(sp², ferrocene)] bond of 1c is more reactive than the σ[Pd-C(sp³)] bond of 1d.     

PhIO-mediated Synthesis of Ketones from Alkynes and Alkenes

A facile and efficient method for the preparation of methyl ketones was developed in the reaction of alkynes and alkenes with PhIO-BF3·Et2O.The reaction features mild conditions,short time and metal-free catalyst.The possible mechanism for the formation of methyl ketones was proposed.H2O functions as both a nucleophile and an oxygen source.     

Rhodium vinylidene and alkyne complexes containing a pendant uracil group

Reaction of HCCUr (Ur = uracil) with [RhCl(PiPr₃)₂] results in the formation of the vinylidene complex [RhCl(PiPr₃)₂(CC{H}Ur)]. In the solid state this complex forms a hydrogen bonded network which consists of complementary interactions between uracil groups on neighbouring rhodium complexes and with the methanol of crystallisation. The η²-alkyne complexes [RhCl(PiPr₃)₂(η²-PhCCUr)] and [Rh(η⁵-C₅H₅)(PiPr₃)(η²-PhCCUr)] have also been prepared. In contrast to the behaviour of [Rh(η⁵-C₅H₅)(PiPr₃)(η²-PhCCUr)], [RhCl(PiPr₃)₂(η²-PhCCUr)] shows little evidence for the formation of hydrogen bonded aggregates in solution. The difference in behaviour between the two species is rationalised on the basis of steric effects.     

Synthesis and characterisation of monomeric, dimeric and polymeric ferrocenylacetylides. Crystal structure of 1,1′-bis(phenylethynyl)ferrocene

The reactions of alkynyltrimethylstannanes with 1,1′-dilithioferrocene have given several ferrocenylacetylides, namely 1-pheny]-ethynyl-1′-iodo-ferrocene (1), 1,1′-bis(phenylethynyl)ferrocene (2), 1,4-di(1′-iodoferrocenylethynyl)benzene (3) and poly[1,4-(1′-ferrocenylethynyl)ethynylbenzene] (4). The versatility of this reaction for the formation of ferrocenylacetylides is demonstrated. The crystal structure of 2 has been determined, and shown to involve a linear array of the groups with a cis arrangement of the phenylethynyl ligands.     

Rhodium-catalyzed 1,4-addition of terminal alkynes to vinyl ketones

The metal complex Rh(acac)(CO)₂ in the presence of an eqimolar amount of tris(o-methoxyphenyl)phosphine provides a useful catalyst system for the 1,4-addition of alkynes to unsubstituted vinyl ketones. Best yields are obtained when the transformation is performed in benzene at reflux with an excess of vinyl ketone. Both aryl and alkyl substituted alkynes participate in the reaction. Primary alcohols and alkyl chlorides are well tolerated under these reaction conditions. The reaction also proceeds in aqueous solvent mixtures, unlike most organometallic addition reactions.     

Reactions of Ru(CCPh)(L2)Cp* (L2=dppm, dppe) with tetracyanoethene: cycloaddition, formation of monodentate dppm and dppmO complexes and migration of CN to ruthenium

Reactions of FcCCH (a), HCCCCFc (b) and FcCCCCFc (c) with Ru₃(CO)₁₀(NCMe)₂ (all) and Ru₃(μ-dppm)(CO)₁₀ (b and c only) are described. Among the products, the complexes Ru₃(μ₃-RC₂R′)(μ-CO)(CO)₉ (R=H, R′=Fc 1, CCFc 2; R=R′=Fc 5), Ru₃(μ-H)(μ₃-C₂CCFc)(μ-dppm)(CO)₇ 3, Ru₃(μ₃-FcC₂CCFc)(μ-dppm)(μ-CO)(CO)₇ 6 and Ru₃{μ₃-C₄Fc₂(CCFc)₂}(μ-dppm)(μ-CO)(CO)₅ 7 were characterised, including single-crystal structure determinations for 1, 3, 5 and 7; that of 7 did not differ significantly from an earlier study of a mixed CH₂Cl₂–C₆H₆ solvate.     

Reactivity of cationic decamethylmetallocene complexes towards ketones

Reaction of decamethylmetallocene cations [Cp∗₂M]⁺ (M = Sc, Ti, V) with acetone and benzophenone resulted in the formation of the corresponding acetone adducts [Cp∗₂M(OCMe₂)_n]⁺ (M = Sc, n = 2; M = Ti, n = 1; M = V, n = 1) and benzophenone adducts [Cp∗₂M(OCPh)]⁺. The stoichiometry of these adducts is determined by both the electronic configuration of the metal center as well as steric pressure imparted by the large Cp∗-ligands. In addition, the M-O-C angle is controlled by the number of free valence orbitals of the Cp∗₂M unit.     

Organometallic Triskelia: Novel Tris(vinylideneruthenium(II)), Tris(alkynylruthenium(II)), and Triruthenium–Triferrocenyl Complexes

Incorporation of a redox-passive bridge affords three identical redox systems in the triskelion-shaped, carbon-rich, polyvinylidenemetal complex 1 . The complex was isolated from the activation of the tripodal polyyne 1,3,5-(HC≡CC₆H₄C≡C)₃C₆H₃ with [RuCl₂({(Ph₂P)₂C₂H₄}₂] and further converted into polyynylmetal complexes and a triple ferrocenyl-substituted ruthenium complex.     

Cyclopalladation of N-phenyl-4-ferrocenylmethylpyrazoles: Crystal structure of [Pd{κ-C,N-C6H4-1-[(3,5-Me2-C3N2)-CH2-(η-C5H4)Fe(η-C5H5)]}Cl(PPh3)] · CH2Cl2

The synthesis and characterization of pyrazole derivatives of general formula [C₆H₄-4-R-1-{(3,5-Me₂-C₃N₂)-CH₂-(η⁵-C₅H₄)Fe(η⁵-C₅H₅)}] [R = OMe (1a) or H (1b)] with a ferrocenylmethyl substituent are described.The study of the reactivity of compounds 1 with palladium(II) acetate has allowed the isolation of complexes (μ-AcO)₂[Pd{κ²-C,N-C₆H₃-4-R-1-[(3,5-Me₂-C₃N₂)-CH₂-(η⁵-C₅H₄)Fe(η⁵-C₅H₅)]}]₂ (2) [R = OMe (2a) or H (2b)] that contain a bidentate [C(sp², phenyl), N]⁻ ligand and a central “Pd(μ-AcO)₂Pd” unit.Furthermore, treatment of 2 with LiCl produced complexes (μ-Cl)₂[Pd{κ²-C,N-C₆H₃-4-R-1-[(3,5-Me₂-C₃N₂)-CH₂-(η⁵-C₅H₄)Fe(η⁵-C₅H₅)]}]₂ (3) [R = OMe (3a) or H (3b)] that arise from the replacement of the acetato ligands by the Cl⁻.Compounds 2 and 3 also react with PPh₃ giving the monomeric complexes [Pd{κ²-C,N-C₆H₃-4-R-1-[(3,5-Me₂-C₃N₂)-CH₂-(η⁵-C₅H₄)Fe(η⁵-C₅H₅)]}X(PPh₃)] {X⁻ = AcO⁻ and R = OMe (5a) or H (5b) or X⁻ = Cl⁻ and R = OMe (6a) or H (6b)}, where the phosphine is in a cis-arrangement to the metallated carbon atom. Treatment of 3 with thallium(I) acetylacetonate produced [Pd{κ²-C,N-C₆H₃-4-R-1-[(3,5-Me₂-C₃N₂)-CH₂-(η⁵-C₅H₄)Fe(η⁵-C₅H₅)]}(acac)] (7) [R = OMe (7a) or H (7b)]. Electrochemical studies of the free ligands and the cyclopalladated complexes are also reported. The dimeric complexes 3 also react with MeO₂C-CC-CO₂Me (in a 1:4 molar ratio) giving [Pd{(MeO₂C-CC-CO₂Me)₂C₆H₃-4-R-1-[(3,5-Me₂-C₃N₂)-CH₂-(η⁵-C₅H₄)Fe(η⁵-C₅H₅)]}Cl] (8) [R = OMe (8a) or H (8b)], which arise from the bis(insertion) of the alkyne into the σ{Pd-C(sp², phenyl)} bond of 3.     

Baeyer-Villiger oxidation of ketones with hydrogen peroxide catalyzed by Sn-palygorskite

Palygorskite-supported Sn complexes were prepared by a simple procedure. Cyclic ketones and acyclic ketones were oxidized by hydrogen peroxide in a reaction catalyzed by palygorskite-supported Sn complexes, affording corresponding lactones or esters with selectivity for the product of 90-100%. The catalysts can be recycled for several times without significant decline in catalytic activity.     

Extension of polar GC-SAFT to systems containing some oxygenated compounds: Application to ethers, aldehydes and ketones

The GC-SAFT equation of state proposed by Tamouza et al. (2004) [51], extended to polar molecular fluids NguyenHuynh et al. (2008) [32], is here applied to model vapor-liquid phase equilibria of various binary mixtures containing at least one oxygenated compound belonging to ethers, ketones or aldehydes chemical families.These systems are modeled using a polar version of the three different versions of SAFT-EOS (original, VR-SAFT and PC-SAFT) in a predictive manner: binary interaction parameters k_ij and l_ij are all set to zero.In the case of alcohol + ether, +ketone, +aldehyde systems, a cross-association interaction between an oxygenated compound (non self-associating compound) and an alcohol is necessary to model/predict accurately the mixture VLE. The corresponding association parameters are assumed to be equal to the self-association parameters of pure 1-alkanols.The above-cited systems have been treated in a comprehensive manner. The general agreement between polar GC-SAFT and experimental data is good (within 4-5% deviation on pressure), similar to the one obtained on previously investigated systems using GC-SAFT.     

‘Click’ synthesis of ferrocenyl-, biferrocenyl-, and cobalticenyl-triazolyl-β-cyclodextrins

Cu^I-catalyzed Huisgen-type dipolar ‘click’ reactions between azidomethyl-β-cyclodextrin and ethynylferrocene, ethylnylcobaltocenium hexafluorophosphate, and bis(ethynyl)-biferrocene yield the corresponding metallocenyl-1,2,3-triazolyl-β-cyclodextrins. The monometallocenyl 1,2,3-triazolyl-β-cyclodextrins are soluble in water, unlike the biferrocene derivative.     

Metal-free catalytic reduction of aldehydes,ketones,aldimines,and ketimines

<正>The metal-free combination of catalytic amounts of PPh_3,B(C_6F_5)_3,and PhSiH_3 can efficiently hydrosilylate aldehydes, ketones,aldimines and ketimines to afford the corresponding reduction products in good yields.     

Click chemistry inspired synthesis of ferrocene amino acids and other derivatives

This work reports the synthesis of a wide range of ferrocenyl-amino acids and other derivatives in excellent yield. Diverse amino acid containing azides were synthesized and ligated to ferrocene employing click reaction to access ferrocenyl amino acids. Chiral alcohols, esters, diols, amines containing azido group were tagged to ferrocene via click reaction to generate ferrocene derived chiral derivatives. A novel strategy for direct incorporation of ferrocene into a peptide and a new route to 1, 1′disubstituted ferrocene amino acid derivative are reported.     

Some aspects of organosilicon and ferrocene chemistry

This review deals with three topics selected from my researches carried out over a period of nearly 40 years up to my retirement in 1983, namely (1) methylpolysilane chemistry, (2) some chemical properties of ferrocene-substituted silicon compounds and (3) some organic syntheses catalyzed by ferrocenylphosphine-transition metal complexes.