J. A. Gladysz

Handbook of fluorous chemistry

Preface.1. Fluorous Chemistry: Scope and Definition (I. Horvath, et al.).2. A Personal View of the History of Fluorous Chemistry (I. Horvath).3. Fluorous Solvents and Related Media (J. Gladysz & C. Emnet).4. Strategies for the Recovery of Fluorous Catalysts and Reagents: Design and Evaluation (J. Gladysz & R. Correa de Costa).5. Ponytails: Structural and Electronic Considerations (J. Gladysz).6. Partition Coefficients Involving Fluorous Solvents (J. Gladysz, et al.).7. Separations with Fluorous Silica Gel and Related Materials (D. Curran).8. Light Fluorous Chemistry-A User-s Guide (D. Curran).9. Getting Started in Synthesis: A Tabular Guide to Selected Monofunctional Fluorous Compounds (J. Rabai).10. Highlights of Applications in Synthesis and Catalysis.11. Preparations.12. Applications of Fluorous Compounds in Materials Chemistry.13. Fluorous Materials for Biomedical Uses (J. Riess).14. Fun and Games with Fluorous Chemistry (J. Rabai).Index.

Fluorous chemistry: from biphasic catalysis to a parallel chemical universe and beyond

Abstract The development of the title discipline is briefly summarized, and the general topics of the articles in this issue introduced. Definitions are proposed for the terms ‘fluorous’, ‘fluorous medium’, ‘fluorous separation technique’, ‘fluorous tag’, ‘fluorous reaction component’, ‘fluorous reaction’, and ‘fluorous chemistry’.

Chemistry in fluorous media: a user's guide to practical considerations in the application of fluorous catalysts and reagents

Abstract Fluorous solvents commonly exhibit temperature-dependent miscibilities with organic solvents. Thus, catalysts and reagents that have high affinities for fluorous solvents can be used in protocols that combine the advantages of one-phase chemistry (higher temperature) and biphase product separation (lower temperature). This review provides a ‘how to’ guide with respect to solvent sources, and solubility and polarity characteristics. All currently available partition coefficients for fluorous catalysts and reagents, as well as various adducts and products, are tabulated.

Thermomorphic fluorous imine and thioether palladacycles as precursors for highly active Heck and Suzuki catalysts; evidence for palladium nanoparticle pathways

p-Iodobenzaldehyde is elaborated to the fluorous alcohol p-Rf8(CH2)3C6H4CH(OH)(CH2)2Rf8 (three steps/80%; Rf8 = n-C8F17), which is converted to imine p-Rf8(CH2)3C6H4C(N(CH2)3Rf8)(CH2)2Rf8 (6, two steps/93%) and thioether p-Rf8(CH2)3C6H4CH(S(CH2)3Rf8)(CH2)2Rf8 (12, 64%). Reactions with Pd(OAc)2 (AcOH, 95 °C) give palladacycles with [RC6H3CR′N(R)Pd(μ-OAc)]2 (7, 87%) and [RC6H3CHR′S(R)Pd(μ-OAc)]2 (13, 84%) cores. The former reacts with LiCl and LiI to give the corresponding bridging halide complexes (8, 9); LiCl/PPh3 affords monomeric RC6H3CR′N(R)Pd(Cl)(PPh3) (10). Palladacycles 7–9 and 13 are poorly soluble or insoluble in many solvents at 20–24 °C, but much more soluble at higher temperatures. The CF3C6F11/toluene partition coefficients of 6, 7, 12, and 13 are >91∶<9 (24 °C). Both 7 and 13 are excellent catalyst precursors for Heck reactions of aryl halides. Turnover numbers exceed 106 with phenyl iodide under homogeneous conditions in DMF at 140 °C. The palladacycles precipitate as bridging halides upon cooling, and can in theory be recovered by liquid/solid phase separations. However, since the quantities are small, the solvent C8F17Br is added for recycling. Induction periods in both the first and second cycles, and progressively lower activities, are noted. Transmission electron microscopy indicates the formation of soluble palladium nanoparticles. Together with other data, it is proposed that the nanoparticles are the active catalysts, for which the recyclable palladacycles constitute a steady state source, until exhausted. Complex 7 similarly catalyzes the Suzuki reaction (K3PO4, toluene, 130 °C).

New methodology for the introduction of sulfur into organic molecules : Synthesis of anhydrous Li2S, Li2S2 and LiSr species by lithium triethylborohydride reduction of elemental sulfur and disulfides

Abstract Anhydrous THF solutions of Li 2 S or Li 2 S 2 (or chemically equivalent species) are rapidly and quantitatively formed by the reaction of common yellow sulfur with appropriate stoichiometries of commercially available LiEt 3 BH. Only volatile by-products H 2 and Et 3 B are produced; however, the Et 3 B probably associates with the anionic sulfur species generated. Subsequent reaction with electrophiles (alkylating agents or acylating agents) affords sulfide or disulfide derivatives in high yields. In several cases, literature procedures are substantially improved. Disulfides are cleaved to lithium mercaptides by LiEt 3 BH. Subsequent addition of electrophiles affords unsymmetrical sulfides. Trisulfides and tetrasulfides can also be prepared by LiEt 3 BH reduction of S g , but only in low yield.

A new type of insulated molecular wire: a rotaxane derived from a metal-capped conjugated tetrayne.

The platinum butadiynyl complex trans-(C(6)F(5))(p-tol(3)P)(2)Pt(C≡C)(2)H and a CuI adduct of a 1,10-phenanthroline based 33-membered macrocycle react in the presence of K(2)CO(3) and I(2) or O(2) to give a rotaxane (ca. 9%) in which the macrocycle is threaded by the sp carbon chain of trans,trans-(C(6)F(5))(p-tol(3)P)(2)Pt(C≡C)(4)Pt(Pp-tol(3))(2)(C(6)F(5)). The crystal structure and macrocycle/axle electronic interactions are analyzed in detail.

Highly Selective Detection of Silver in the Low ppt Range with Ion-Selective Electrodes Based on Ionophore-Doped Fluorous Membranes

Ionophore-doped sensing membranes exhibit greater selectivities and wider measuring ranges if their membrane matrixes are noncoordinating and solvate interfering ions poorly. This is particularly true for fluorous phases, which are the least polar and polarizable condensed phases known. In this work, fluorous membrane matrixes were used to prepare silver ion-selective electrodes (ISEs). Sensing membranes composed of perfluoroperhydrophenanthrene, sodium tetrakis[3,5-bis(perfluorohexyl) phenyl]borate, and one of four fluorophilic Ag(+)-selective ionophores with one or two thioether groups were investigated. All electrodes exhibited Nernstian responses to Ag(+) in a wide range of concentrations. Their selectivities for Ag(+) over interfering ions were found to depend on host preorganization and the length of the -(CH(2))(n)- spacers separating the coordinating thioether group from the strongly electron withdrawing perfluoroalkyl groups. ISEs based on the most selective of the four ionophores, that is, 1,3-bis(perfluorodecylethylthiomethyl)benzene, provided much higher selectivities for Ag(+) over many alkaline and heavy metal ions than most Ag(+) ISEs reported in the literature (e.g., log K(Ag,J)(pot) for K(+), -11.6; Pb(2+), -10.2; Cu(2+), -13.0; Cd(2+), -13.2). Moreover, the use of this ionophore with a linear perfluorooligoether as membrane matrix and solid contacts consisting of three-dimensionally ordered macroporous (3DOM) carbon resulted in a detection limit for Ag(+) of 4.1 ppt (3.8 × 10(-1)1 M).

Transition Metal Formyl Complexes

Publisher Summary This chapter discusses the synthesis of transition-metal formyl complexes, their physical properties, their reactions, and topics relating to the stability and decomposition of transition-metal formyl complexes. The synthesis, chemical characterization, and physical characterization of transition-metal complexes of new carbon-containing ligands constitute important ongoing objectives of organometallic chemists. In the presence of metallic heterogeneous or homogeneous catalysts, synthesis gas can be converted to a variety of organic molecules (methane, methanol, higher alkanes and alcohols, and glycols). In advance of any experiment, formyl complexes appear deceptively easy to synthesize. Comparisons to methods for transition metal acyl synthesis are instructive. Unfortunately, formic acetic anhydride is not a general reagent for formyl complex synthesis. Formyl complexes are characterized by distinct spectroscopic features. Transition-metal formyl complexes are capable of donating hydride to several classes of substrates, of which ketones and aldehydes are prototypical. A unique reaction of formyl complexes is “formyl transfer,” in which the formyl ligand undergoes apparent migration from one metal to another. Reactions of neutral formyl complexes with alkylating agents can follow different courses. Formyl complexes show varying behavior when treated with protonating agents. Anionic formyl complexes can be reduced when treated with the more potent trialkylborohydride nucleophiles. Neutral formyl complexes that contain ligating CO often decompose by decarbonylation; however, several exceptions exist. It is evident that transition-metal formyl complexes possess a unique and rich chemistry.

Molecular Wires in Single‐Molecule Junctions: Charge Transport and Vibrational Excitations

We investigate the effect of vibrations on the electronic transport through single-molecule junctions, using the mechanically controlled break junction technique. The molecules under investigation are oligoyne chains with appropriate end groups, which represent both an ideally linear electrical wire and an ideal molecular vibrating string. Vibronic features can be detected as satellites to the electronic transitions, which are assigned to longitudinal modes of the string by comparison with density functional theory data.

Cubic Nonlinear Optical Properties of Platinum-Terminated Polyynediyl Chains

The wavelength dependence of the cubic nonlinearity of ligated platinum-terminated polyynes trans, trans-{(p-MeC6H4)3P}2(p-MeC6H4)Pt(C[triple bond]C)n Pt(p-C6H4Me){P(p-C6H4Me)3}2 (n = 3-6, 8, 10, 12) has been examined by femtosecond Z-scan studies in the wavelength range 520-1500 nm and the results rationalized by density functional theory calculations on the model complexes trans, trans-(H3P)2(C6H5)Pt(C[triple bond]C)n Pt(C6H5)(PH3)2 (n = 2-8, 10, 12). Although the final states for one- and two-photon transitions are not the same in these centrosymmetric molecules, the Z-scan studies reveal coincidences in one-photon absorption with features in the frequency dependencies of both real and imaginary parts of the cubic hyperpolarizability, as well as inflections in the frequency dependencies of the real part of gamma that correspond to resonances in the imaginary part of gamma. The theoretical studies suggest that the linear absorption spectra are dominated by X(1)A g --> n(1)B(3u) transitions, with the first state of B(3u) symmetry playing a steadily diminishing role upon oligoyne chain lengthening. The theoretical studies also predict a red-shift of two-photon absorption (TPA) profile with increasing conjugation length, and a significant enhancement on proceeding from the shortest to the longest chromophore, trends that are observed experimentally. The experimental low-energy TPA maxima for these complexes can be approximated by a simple Gaussian profile. The sp-carbon chain-length dependence of linear and nonlinear absorption maxima enable an estimate (neglecting saturation) of 660 and 1000 nm for the infinite carbon chain, carbyne.