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911.
A series of 2-aryl-1-thioalkyl-2-propenes have been synthesized by treating the corresponding thioalkylated acetophenones with the anion of methyl phosphonate. 相似文献
912.
Mark A. Fox 《Journal of organometallic chemistry》2009,694(15):2350-4677
The five-coordinate complex [RuCl(dppe)2]OTf ([2]OTf) is obtained in high yield by the sequential reduction of RuCl3 · nH2O to RuCl2(PPh3)3, subsequent phosphine substitution to give trans-RuCl2(dppe)2 (trans-1) and finally chloride abstraction (AgOTf, CH2Cl2). The use of [2]OTf as an entry point to mono-acetylide complexes trans-RuCl(CCC6H4R-4)(dppe)2 (3) is described, and represents an alternative route to the long-standing methods based on cis-RuCl2(dppe)2 (cis-1), which is always prepared as a mixture with the more thermodynamically stable trans isomer when prepared by phosphine substitution reactions of RuCl2(dmso)4. The molecular structures of [2]OTf, trans-RuCl(CCC6H4OMe-4)(dppe)2 (3b), trans-RuCl(CCC6H4Me-4)(dppe)2 (3c) and trans-RuCl(CCC6H4CO2Me-4)(dppe)2 (3e) are described. A facile and reproducible synthesis of cis-1 is also reported. 相似文献
913.
Mark A. Fox Carlo Nervi Antonella Crivello Andrei S. Batsanov Judith A. K. Howard Kenneth Wade Paul J. Low 《Journal of Solid State Electrochemistry》2009,13(10):1483-1495
The influence of aryl ring substituents X (F, OMe, NMe2, NH2, OH and O−) on the physical and electronic structure of the ortho-carborane cage in a series of C,C′-diaryl-ortho-carboranes, 1-(4-XC6H4)-2-Ph-1,2-C2B10H10 has been investigated by crystallographic, spectroscopic [nuclear magnetic resonance (NMR), UV–vis], electrochemical and
computational methods. The cage C1–C2 bond lengths in this carborane series show small variations with the electron-donating
strength of the substituent X, but there is no evidence of a fully evolved quinoid form within the aryl substituents in the
ground state. In the 11B and 13C NMR spectra, the ‘antipodal’ shift at B12, and the C1 shift correlates with the Hammett σ
p value of the substituent X. The UV–visible absorption spectra of the cluster compounds show marked differences when compared
with the spectra of the analogous substituted benzenes. These spectroscopic differences are attributed to variation in contributions
from the cage orbitals to the unoccupied/virtual orbitals involved in the transitions responsible for the observed absorption
bands. Electrochemical studies (cyclic and square-wave voltammetry) carried out on the diarylcarborane series reveal that
one-electron reduction takes place at the cage in every case with the voltage required for reduction of the cage influenced
by the electron-donating strength of the substituent X, affording a series of carborane radicals with formal [2n + 3] electron
counts.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
914.
Brian J. Fox Matthew D. Millard Antonio G. DiPasquale Dr. Arnold L. Rheingold Prof. Dr. Joshua S. Figueroa Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(19):3372-3372
Binding of thallium(I) by low‐valent nickel establishes the use of main‐group ions as coordination site protection agents for transition‐metal centers. As described by J. S. Figueroa and co‐workers in their Communication on page 3473 ff. , Tl(I) coordination provides a route to the preparation of a coordinatively unsaturated nickel tris‐isocyanide complex. Thallium functions as a protecting group towards Lewis bases and is readily removed upon addition of halide ions.
915.
Brückner C Götz DC Fox SP Ryppa C McCarthy JR Bruhn T Akhigbe J Banerjee S Daddario P Daniell HW Zeller M Boyle RW Bringmann G 《Journal of the American Chemical Society》2011,133(22):8740-8752
The synthesis and chiral resolution of free-base and Ni(II) complexes of a number of derivatives of meso-tetraphenylmorpholinochlorins, with and without direct β-carbon-to-o-phenyl linkages to the flanking phenyl groups, is described. The morpholinochlorins, a class of stable chlorin analogues, were synthesized in two to three steps from meso-tetraphenylporphyrin. The conformations and the relative stereostructures of a variety of free-base and Ni(II) complexes of these morpholinochlorins were elucidated by X-ray diffractometry. Steric and stereoelectronic arguments explain the relative stereoarray of the morpholino-substituents, which differ in the free-base and Ni(II) complexes, and in the monoalkoxy, β-carbon-to-o-phenyl linked morpholinochlorins, and the dialkoxy derivatives. The Ni(II) complexes were all found to be severely ruffled whereas the free-base chromophores are more planar. As a result of the helimeric distortion of their porphyrinoid chromophores, the ruffled macrocycles possess a stable inherent element of chirality. Most significantly, resolution of the racemic mixtures was achieved, both by classical methods via diastereomers and by HPLC on a chiral phase. Full CD spectra were recorded and modeled using quantum-chemical computational methods, permitting, for the first time, an assignment of the absolute configurations of the chromophores. The report expands the range of known pyrrole-modified porphyrins. Beyond this, it introduces large chiral porphyrinoid π-systems that exist in the form of two enantiomeric, stereochemically stable helimers that can be resolved. This forms the basis for possible future applications, for example, in molecular-recognition systems or in materials with chiroptic properties. 相似文献
916.
Taylor MT Blackman ML Dmitrenko O Fox JM 《Journal of the American Chemical Society》2011,133(25):9646-9649
Computation was used to design a trans-cyclooctene derivative that displays enhanced reactivity in the tetrazine-trans-cycloctene ligation. The optimized derivative is an (E)-bicyclo[6.1.0]non-4-ene with a cis-ring fusion, in which the eight-membered ring is forced to adopt a highly strained 'half-chair' conformation. Toward 3,6-dipyridyl-s-tetrazine in MeOH at 25 °C, the strained derivative is 19 and 27 times more reactive than the parent trans-cyclooctene and 4E-cyclooct-4-enol, respectively. Toward 3,6-diphenyl-s-tetrazine in MeOH at 25 °C, the strained derivative is 160 times more reactive than the parent trans-cyclooctene. 相似文献
917.
Weber L Kahlert J Brockhinke R Böhling L Brockhinke A Stammler HG Neumann B Harder RA Fox MA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(27):8347-8357
Seven derivatives of 1,2-dicarbadodecaborane (ortho-carborane, 1,2-C(2)B(10)H(12)) with a 1,3-diethyl- or 1,3-diphenyl-1,3,2-benzodiazaborolyl group on one cage carbon atom were synthesized and structurally characterized. Six of these compounds showed remarkable low-energy fluorescence emissions with large Stokes shifts of 15100-20260 cm(-1) and quantum yields (Φ(F)) of up to 65% in the solid state. The low-energy fluorescence emission, which was assigned to a charge-transfer (CT) transition between the cage and the heterocyclic unit, depended on the orientation (torsion angle, ψ) of the diazaborolyl group with respect to the cage C-C bond. In cyclohexane, two compounds exhibited very weak dual fluorescence emissions with Stokes shifts of 15660-18090 cm(-1) for the CT bands and 1960-5540 cm(-1) for the high-energy bands, which were assigned to local transitions within the benzodiazaborole units (local excitation, LE), whereas four compounds showed only CT bands with Φ(F) values between 8-32%. Two distinct excited singlet-state (S(1)) geometries, denoted S(1)(LE) and S(1)(CT), were observed computationally for the benzodiazaborolyl-ortho-carboranes, the population of which depended on their orientation (ψ). TD-DFT calculations on these excited state geometries were in accord with their CT and LE emissions. These C-diazaborolyl-ortho-carboranes were viewed as donor-acceptor systems with the diazaborolyl group as the donor and the ortho-carboranyl group as the acceptor. 相似文献
918.
Ashutosh Goel John S. McCloy Kevin M. Fox Clifford J. Leslie Brian J. Riley Carmen P. Rodriguez Michael J. Schweiger 《Journal of Non》2012,358(3):674-679
Sodium- and aluminum-rich high-level nuclear waste glasses are prone to nepheline (NaAlSiO4) crystallization. Since nepheline removes three moles of glass-forming oxides (Al2O3 and SiO2) per mole of Na2O, the formation of this phase can result in severe deterioration of the chemical durability in a given glass. The present study aims to investigate the relationships between the molecular-level structure and the crystallization behavior of sodium alumino-borosilicate-based simulated high-level nuclear waste glasses with infrared spectroscopy (FTIR) and X-ray diffraction, respectively. The molecular structure of most of the investigated glasses comprise a mixture of Q2 and Q3 (Si) units while aluminum and boron are predominantly present in tetrahedral and trigonal coordination, respectively. The increasing boron content has been shown to suppress the nepheline formation in the glasses. The structural influence of various glass components on nepheline crystallization is discussed. 相似文献
919.
Yanfeng Jiang Olivier Blacque Dr. Thomas Fox Dr. Christian M. Frech Dr. Heinz Berke Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(7):2240-2249
The five‐coordinated ReI hydride complexes [Re(Br)(H)(NO)(PR3)2] (R=Cy 1 a , iPr 1 b ) were reacted with benzylbromide, thereby affording the 17‐electron mononuclear ReII hydride complexes [Re(Br)2(H)(NO)(PR3)2] (R=Cy 3 a , iPr 3 b ), which were characterized by EPR, cyclic voltammetry, and magnetic susceptibility measurements. In the case of dibromomethane or bromoform, the reaction of 1 afforded ReII hydrides 3 in addition to ReI carbene hydrides [Re(?CHR1)(Br)(H)(NO)(PR3)2] (R1=H 4 , Br 5 ; R=Cy a , iPr b ) in which the hydride ligand is positioned cis to the carbene ligand. For comparison, the dihydrogen ReI dibromide complexes [Re(Br)2(NO)(PR3)2(η2‐H2)] (R=Cy 2 a , iPr 2 b ) were reacted with allyl‐ or benzylbromide, thereby affording the monophosphine ReII complex salts [R3PCH2R′][Re(Br)4(NO)(PR3)] (R′=? CH?CH2 6 , Ph 7 ). The reduction of ReII complexes has also been examined. Complex 3 a or 3 b can be reduced by zinc to afford 1 a or 1 b in high yield. Under catalytic conditions, this reaction enables homocoupling of benzylbromide (turnover frequency (TOF): 3 a 150, 3 b 134 h?1) or allylbromide (TOF: 3 a 575, 3 b 562 h?1). The reaction of 6 a and 6 b with zinc in acetonitrile affords in good yields the monophosphine ReI complexes [Re(Br)2(NO)(MeCN)2(PR3)] (R=Cy 8 a , iPr 8 b ), which showed high catalytic activity toward highly selective dehydrogenative silylation of styrenes (maximum TOF of 61 h?1). Single‐electron transfer (SET) mechanisms were proposed for all these transformations. The molecular structures of 3 a , 6 a , 6 b , 7 a , 7 b , and 8 a were established by single‐crystal X‐ray diffraction studies. 相似文献
920.
Mezyk SP Helgeson T Cole SK Cooper WJ Fox RV Gardinali PR Mincher BJ 《The journal of physical chemistry. A》2006,110(6):2176-2180
Halonitromethanes are disinfection-byproducts formed during ozonation and chlorine/chloramine treatment of waters that contain bromide ion and natural organic matter. In this study, the chemical kinetics of the free-radical-induced degradations of a series of halonitromethanes were determined. Absolute rate constants for hydroxyl radical, *OH, and hydrated electron, e(aq)-, reaction with both chlorinated and brominated halonitromethanes were measured using the techniques of electron pulse radiolysis and transient absorption spectroscopy. The bimolecular rate constants obtained, k (M(-1) s(-1)), for e(aq)-/*OH, respectively, were the following: chloronitromethane (3.01 +/- 0.40) x 10(10)/(1.94 +/- 0.32) x 10(8); dichloronitromethane (3.21 +/- 0.17) x 10(10)/(5.12 +/- 0.77) x 10(8); bromonitromethane (3.13 +/- 0.06) x 10(10)/(8.36 +/- 0.57) x 10(7); dibromonitromethane (3.07 +/- 0.40) x 10(10)/(4.75 +/- 0.98) x 10(8); tribromonitromethane (2.29 +/- 0.39) x 10(10)/(3.25 +/- 0.67) x 10(8); bromochloronitromethane (2.93 +/- 0.47) x 10(10)/(4.2 +/- 1.1) x 10(8); bromodichloronitromethane (2.68 +/- 0.13) x 10(10)/(1.02 +/- 0.15) x 10(8); and dibromochloronitromethane (2.95 +/- 0.43) x 10(10) / (1.80 +/- 0.31) x 10(8) at room temperature and pH approximately 7. Comparison data were also obtained for hydroxyl radical reaction with bromoform (1.50 +/- 0.05) x 10(8), bromodichloromethane (7.11 +/- 0.26) x 10(7), and chlorodibromomethane (8.31 +/- 0.25) x 10(7) M(-1) s(-1), respectively. These rate constants are compared to recently obtained data for trichloronitromethane and bromonitromethane, as well as to other established literature data for analogous compounds. 相似文献