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21.
Dalton GT Viau L Waterman SM Humphrey MG Bruce MI Low PJ Roberts RL Willis AC Koutsantonis GA Skelton BW White AH 《Inorganic chemistry》2005,44(9):3261-3269
Reaction of [WIr3(mu-CO)3(CO)8(eta-C5Me5)] (1c) with [W(C[triple bond]CPh)(CO)3(eta-C5H5)] afforded the edge-bridged tetrahedral cluster [W2Ir3(mu4-eta2-C2Ph)(mu-CO)(CO)9(eta-C5H5)(eta-C5Me5)] (3) and the edge-bridged trigonal-bipyramidal cluster [W3Ir3(mu4-eta2-C2Ph)(mu-eta2-C=CHPh)(Cl)(CO)8(eta-C5Me5)(eta-C5H5)2] (4) in poor to fair yield. Cluster 3 forms by insertion of [W(C[triple bond]CPh)(CO)3(eta-C5H5)] into Ir-Ir and W-Ir bonds, accompanied by a change in coordination mode from a terminally bonded alkynyl to a mu4-eta2 alkynyl ligand. Cluster 4 contains an alkynyl ligand interacting with two iridium atoms and two tungsten atoms in a mu4-eta2 fashion, as well as a vinylidene ligand bridging a W-W bond. Reaction of [WIr3(CO)11(eta-C5H5)] (1a) or 1c with [(eta-C5H5)(CO)2 Ru(C[triple bond]C)Ru(CO)2(eta-C5H5)] afforded [Ru2WIr3(mu5-eta2-C2)(mu-CO)3(CO)7(eta-C5H5)2(eta-C5R5)] [R = H (5a), Me (5c)] in low yield, a structural study of 5a revealing a WIr3 butterfly core capped and spiked by Ru atoms; the diruthenium ethyndiyl precursor has undergone Ru-C scission, with insertion of the C2 unit into a W-Ir bond of the cluster precursor. Reaction of [W2Ir2(CO)10(eta-C5H5)2] with the diruthenium ethyndiyl reagent gave [RuW2Ir2{mu4-eta2-(C2C[triple bond]C)Ru(CO)2(eta-C5H5)}(mu-CO)2(CO)6(eta-C5H5)3] (6) in low yield, a structural study of 6 revealing a butterfly W2Ir2 unit capped by a Ru(eta-C5H5) group resulting from Ru-C scission; the terminal C2 of a new ruthenium-bound butadiyndiyl ligand has been inserted into the W-Ir bond. Reaction between 1a, [WIr3(CO)11(eta-C5H4Me)] (1b), or 1c and [(eta-C5H5)(CO)3W(C[triple bond]CC[triple bond]C)W(CO)3(eta-C5H5)] afforded [W2Ir3{mu4-eta2-(C2C[triple bond]C)W(CO)3(eta-C5H5)}(mu-CO)2(CO)2(eta-C5H5)(eta-C5R5)] [R = H (7a), Me (7c); R5 = H4Me (7b)] in good yield, a structural study of 7c revealing it to be a metallaethynyl analogue of 3. 相似文献
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Ir. H. A. Waterman 《Rheologica Acta》1969,8(1):22-38
Summary The propagation of elastic waves (both longitudinal and transverse) through polyurethane rubbers filled with different amounts
of sodium chloride particles was studied at 0.8 MHz and 5 MHz. At a constant filler concentration (∼10% by volume), the velocity
of these waves appeared to be independent of filler size. On the other hand, both velocities were found to increase with filler
content. From the wave velocities, the effective modulus for longitudinal waves, L, bulk modulus, K, and shear modulus, G,
were calculated according to the relations for a homogeneous isotropic material. All three moduli appear to be monotonically
increasing functions of filler content, c, over the whole experimentally accessible temperature range (−80°C to +80°C for
L and K; −80°C to about −30°C for G) and they, moreover, reflect the glass-rubber transition of the binder. Poissons ratio,
μ, was found to decrease with increasing filler content and shows a rise at about −30°C as a result of the approach of the
glass-rubber transition.
The attenuation of the elastic waves was also measured in the temperature ranges mentioned. For filler particles beyond a
critical size both tan δL and tan δG in the hard region are independent of the filler content within the accuracy of the measurements. The critical size depends
on the type of wave and on its frequency. In the rubbery region, however, tan δL increases with particle size (at a constant content of 10% by volume) and even shows an enhancement with the smallest particles
(1–5 μ) at 0.8 MHz. Moreover, it is found that for the same filler size tan δL increases with filler content. In some cases an anomalous damping behaviour was found, such that in the rubbery region the
attenuation rises indefinitely with temperature. For filler particles larger than the above-mentioned critical size, tan δG and tan δL increase in the hard region as well. Finally, the experimental results are compared with existing theories on the elastic
properties of and wave propagation through composite media. 相似文献
26.
F. M. Schertz S. Rask E. Kaplan H. C. Waterman und T. L. Mc Namara 《Fresenius' Journal of Analytical Chemistry》1936,107(1-2):44
Ohne Zusammenfassung 相似文献
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AT-Schottky group is a discrete group of Möbius transformations whose generators identify pairs of possibly-tangent Jordan curves on the complex sphere ?. If the curves are Euclidean circles, then the group is termed classicalT-Schottky. We describe the boundary of the space of classicalT-Schottky groups affording two parabolic generators within the larger parameter space of allT-Schottky groups with two parabolic generators. This boundary is surprisingly different from that of the larger space. It is analytic, while the boundary of the larger space appears to be fractal. Approaching the boundary of the smaller space does not correspond to pinching; circles necessarily become tangent, but extra parabolics need not develop. As an application, we construct an explicit one parameter family of two parabolic generator non-classicalT-Schottky groups. 相似文献
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