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111.
Miller TA Jeffery JC Ward MD Adams H Pope SJ Faulkner S 《Dalton transactions (Cambridge, England : 2003)》2004,(10):1524-1526
Co-crystallisation of the anionic cyanometallate chromophore [Ru(bipy)(CN)4]2- with Yb(III) provides coordination polymers or oligomers containing Ru-CN-Yb bridges; in [K(H2O)4][Yb(H2O)6][Ru(bipy)(CN)4]2.5H2O Ru-->Yb energy-transfer (k > 5 x 10(6) s(-1)) results in partial quenching of the Ru-based luminescence and sensitised near-IR luminescence from the Yb(III) unit. 相似文献
112.
Ogrin D van Poppel LH Bott SG Barron AR 《Dalton transactions (Cambridge, England : 2003)》2004,(21):3689-3694
The reaction of AlMe(3) and [((t)Bu)(2)Al(micro-OPh)](2) with pyrazine (pyz), 4,4'-bipyridine (4-4'-bipy), 1,2-bis(4-pyridyl)ethane (bpetha) and 1,2-bis(4-pyridyl)ethylene (bpethe) yields (Me(3)Al)(2)(micro-pyz)(1), (Me(3)Al)(2)(micro-4,4'-bipy)(2), (Me(3)Al)(2)(micro-bpetha)(3), (Me(3)Al)(2)(micro-bipethe)(4), Al((t)Bu)(2)(OPh)(pyz)(5), [((t)Bu)(2)Al(OPh)](2)(micro-4,4-bipy)(6a), [((t)Bu)(2)Al(OPh)](2)(micro-bpetha)(7a), [((t)Bu)(2)Al(OPh)](2)(micro-bipethe)(8a). Compounds 1-4, 6a and 7a have been confirmed by X-ray crystallography. In solution compounds 1-4 undergo a rapid ligand-dissociation equilibrium resulting in a time-average spectrum in the (1)H NMR. In contrast, the solution equilibria for compounds 5-8a are sufficiently slow such that the mono-aluminium compounds may be observed by (1)H NMR spectroscopy: Al((t)Bu)(2)(OPh)(4,4-bipy)(6b), Al((t)Bu)(2)(OPh)(bpetha)(7b) and Al((t)Bu)(2)(OPh)(bpethe)(8b). The inability to isolate [((t)Bu)(2)Al(OPh)](2)(micro-pyz) and the relative stability of each complex is discussed with respect to the steric interactions across the bridging ligand (L) and the electronic effect on one Lewis acid-base interaction by the second Lewis acid-base interaction on the same ligand. 相似文献
113.
Petrie S 《The journal of physical chemistry. A》2005,109(28):6326-6334
Quantum chemical calculations are used to explore the proton-transfer reactivity of O-protonated vinyl alcohol, CH2CHOH2+, with phosphorus nitride, PN. This reaction is relevant to the chemical evolution of interstellar clouds, since O-protonated vinyl alcohol has been postulated (and tentatively identified) as a product of the association reaction between interstellar H3O+ and C2H2, while PN is the most widespread and abundant phosphorus-containing molecule seen in astrophysical environments. Furthermore, the reaction exhibits an unusual mechanistic feature, namely, an extended "proton-transport catalysis" mechanism, which we characterize here as a "proton-transfer triple play". The reaction proceeds initially by proton transfer from CH2CHOH2+ to PN, then from PNH+ to CH2CHOH, and finally from CH3CHOH+ to PN, where the emphasized atom indicates the resultant site of protonation/deprotonation. Thus, the ultimate overall bimolecular proton-transfer reaction is expected to occur as CH2CHOH2+ + PN --> CH3CHO + PNH+; that is, the apparent favored product channel exhibits not only proton transfer but also keto/enol tautomerization. The triple-play mechanism can be rationalized in terms of the proton affinities of vinyl alcohol, acetaldehyde, and phosphorus nitride, which here are satisfactorily reproduced by high-level ab initio calculations. Other neutrals with a proton affinity appropriate for the possible triple-play mechanism converting CH2CHOH2+ to CH3CHO are also identified, with a view to encouraging experimental investigation of this mechanism. 相似文献
114.
Philip J. Cox Olga A. Melvin Simon J. Garden James L. Wardell 《Journal of chemical crystallography》1995,25(8):469-475
The title organotin carbohydrate, C31H36O6Sn, has been synthesized and its molecular structure has been determined in solution and in the solid state. NMR, infrared, mass and X-ray crystallographic techniques were used. The chiral molecules crystallize in the monoclinic space group P21 withZ=2. The triphenyltin and carbohydrate moieties are linked by a trans methylene-oxygen-methylene arrangement. The pyranosyl ring adopts a twist-boat conformation and the isopropylidene rings adopt different (half-chair and envelope) forms. Solution and solid-state conformations are similar as only three 13C shift values are greater than 2ppm; the 119Sn value is 12 ppm. 相似文献
115.
Let (E, (ie63-01),) be a halfordered plane and call
convex if M contains for any two points a,bM all pointsx between a and b. It is shown that segments [a,b] are convex if and only if (E, (ie63-02)) is the affine plane of order 3, (E, (ie63-03),) is an ordered plane or is near-trivial.
Herrn Professor Johannes Böhm zum 70. Geburtstag gewidmet 相似文献
Herrn Professor Johannes Böhm zum 70. Geburtstag gewidmet 相似文献
116.
We prove two new upper bounds on the size of binary codes with a minimum distance of three, namelyA(10, 3)76 andA(11, 3)152. 相似文献
117.
118.
Simon A. Butler Gillian W. Harris David S. Moss Beatrice A. Gorinsky Margaret J. Adams Sheila Gover 《Journal of chemical crystallography》1994,24(1):1-3
We report the estimation of random errors in the refinement of the rigid body displacements of the -helices of the enzyme 6-phosphogluconate dehydrogenase. Least-squares refinement of the TLS parameters of the helices has been carried out using X-ray reflection data of 2.1 Å resolution, resulting in anR-factor of 19.5%. Standard deviations were estimated from the normal matrix. The results show that the translational mean-square displacements of nearly all the helices are significant at this resolution. However the libration parameters are only significant when the helices have at least four turns. Screw-rotation tensor values cannot be determined at this resolution. 相似文献
119.
120.
1D and 2D five-pulse ESEEM experiments on a PO 3 2? center in γ-irradiated betaine phosphite are presented to study the protons bound to the radical in more detail. The ESEEM results are in accordance with previous ENDOR investigations. From the 2D fivepulse ESEEM experiments the1H ENDOR assignment in the ferroelectric ordered state of betaine phosphite could be completed. Additionally, the occurrence of ordered proton states in the disordered paraelectric high-temperature phase and of disordered proton states in the ordered ferroelectric low-temperature phase as well could be observed due to the enhanced resolution of the 2D method. 相似文献