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Several novel pentamethylcyclopentadienyl complexes of general formula [(C5Me5)IrL3][BF4]2 were prepared including the tris(solvent) precursors [(C5Me5)M(acetone)2(H2O)][BF4]2 (M = Rh, Ir) (1a,b). The X-ray molecular structures of 1a,b were determined at low temperature. Complexes 1a,b are isostructural, and both compounds crystallize in the monoclinic space group P2(1)/c with a = 10.157(3) A, b = 14.038(9) A, c = 16.335(2) A, beta = 99.73(2) degrees, and Z = 4 for 1a and with a = 10.107(9) A, b = 13.994(16) A, c = 15.996(34) A, beta = 99.61(12) degrees, and Z = 4 for 1b. The coordinated water molecule is hydrogen bonded to both BF4(-) anions. Reaction of 1a,b with pyridine (py) afforded the related tris(pyridine) complexes [(C5Me5)M(eta1-(N)-py)3][BF4]2 (M = Rh, Ir) (2a,b). Complex 2b was characterized by X-ray crystallography, monoclinic space group P2(1)/c with a = 8.665(3) A, b = 19.687(7) A, c = 18.408(5) A, beta = 94.17(3) degrees, and Z = 4. Moreover, we prepared the novel neutral compounds (C5Me5)M(eta2-NO3)(eta1-NO3) (M = Rh, Ir) (4a,b) where the anions are bonded to the metal center instead of a coordinating solvent as confirmed by X-ray study on the iridium complex 4b. The latter crystallizes in the orthorhombic space group Pcab with a = 13.032(4) A, b = 14.370(11) A, c = 14.839(18) A, and Z = 8. 相似文献
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Chevreux G Potier N Van Dorsselaer A Bahloul A Houdusse A Wells A Sweeney HL 《Journal of the American Society for Mass Spectrometry》2005,16(8):1367-1376
Among the myosin superfamily, myosin VI differs from all others by a reverse directionality and a particular motility. Little structural information is available for myosin VI. It is known that it binds one calmodulin (CaM) by means of a single "IQ motif" and that myosin VI contains a specific insert located at the junction between the motor domain (MD) and the lever arm, likely to play a critical role for the unusual motility previously observed. Electrospray ionization mass spectrometry (MS) was used to determine the CaM and Ca2+ stoichiometries in several myosin VI constructs. In particular, the experimental conditions required for the observation of multiprotein/Ca2+ noncovalent assemblies are detailed for two truncated MD constructs (less than 20 kDa) and for three full MD constructs (more than 90 KDa). The specificity of the detected stoichiometries is discussed for each construct and the resolving power of Time of Flight mass spectrometry is stressed, in particular for the detection of metal ions binding to high molecular weight complexes. MS reveals a new CaM binding site for myosin VI and highlights a different behavior for the five myosin VI constructs versus Ca2+ binding. In addition to these stoichiometry based experiments, gas-phase dissociation analyses on intact complexes are described. They reveal that Ca2+ transfer between protein partners occurs during the dissociation process for one construct with a full MD. Charge-transfer and dissociation behavior has allowed to draw structural assumptions for the interaction of the MD with the CaM N-terminal lobe. 相似文献
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André Loupy Noelle Philippon Philippe Pigeon Jean Sansoulet Hervé Galons 《合成通讯》2013,43(18):2855-2864
Solid-liquid PTC without added solvent efficiently promotes SNAr reactions of a variety of anionic nucleophiles generated in situ. This methodology is applied with success to some examples concerning non-activated aromatic systems. TDA-1 is the most effective catalyst. 相似文献
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Stephen K. Taylor Dawn DeYoung Lloyd J. Simons James R. Vyvyan ‡ Mary A. Wemple Noelle K. Wood 《合成通讯》2013,43(9):1691-1701
The nucleophilic opening of epoxides by nitrile enolates using an efficient, convenient protocol is described. The diastereoselectivity of this reaction was explored and found to give syn:anti ratios ranging from 1.1:1.0 to 4.8:1.0. 相似文献
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Summary.
We prove convergence of a class of higher order upwind
finite
volume schemes on unstructured grids for scalar conservation laws in
several space dimensions. The result is applied to the discontinuous
Galerkin method due to Cockburn, Hou and Shu.
Received
April 15, 1993 / Revised version received March 13, 1995 相似文献
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Noelle Antony 《代数通讯》2013,41(11):4043-4056
ABSTRACT Baez and Birman introduced the singular braid monoid on n + 1 strings, 𝒮B n+1, which Birman uses in understanding knot invariants. 𝒮? n+1 is the type A n case of an infinite class of monoids known as singular Artin monoids and denoted by 𝒮G M for a Coxeter matrix M. Birman conjectured, and Paris proved, that 𝒮B n+1 embeds in the complex algebra of the braid group under the desingularisation map or Vassiliev homomorphism, η. In effect, Birman's conjecture generalizes to arbitrary types since, as noted by Corran, the Vassiliev homomorphism from 𝒮G M to the algebra of the corresponding Artin group is well defined. We deduce general combinatorial results regarding divisibility in positive singular Artin monoids, and when M is of finite type, a well-defined positive form for 𝒮G M is produced. These facts are then invoked to infer that, when M is of finite type, η is injective on pairs of words such that a common multiple exists for their positive form. 相似文献
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Noelle Antony 《代数通讯》2013,41(9):3329-3346
We explore some combinatorial properties of singular Artin monoids and invoke them to prove that a positive singular Artin monoid of arbitrary Coxeter type necessarily injects into the corresponding singular Artin monoid. This is an extension of L. Pari' result that positive Artin monoids embed in the correpsonding Artin groups: Adjoining inverses of the generators does not produce any new identities between words that do not involve those inverses. 相似文献