Silylene‐Bridged Tetranuclear Palladium Cluster as a Catalyst for Hydrogenation of Alkenes and Alkynes
作者:Chikako Yanagisawa、Seiji Yamazoe、Yusuke Sunada
DOI:10.1002/cctc.202001387
日期:2021.1.12
A planartetranuclearpalladium cluster was obtained from the reaction of a cyclotetrasilane with [Pd(CNtBu)2]3. Single‐crystal X‐ray diffraction analysis and DFT calculations revealed that the tetranuclear framework of the cluster was supported effectively by the bridging organosilylene ligand. Although [Pd(CNtBu)2]3 as well as mononuclear palladium bis(silyl) complex, cis‐Pd(SiMePh2)2(CNtBu)2, do
通过环四硅烷与[Pd(CN t Bu)2 ] 3的反应获得平面四核钯簇。X射线单晶衍射分析和DFT计算表明,桥联的有机硅配体有效地支持了簇的四核骨架。尽管[Pd(CN t Bu)2 ] 3以及单核钯双(甲硅烷基)络合物,但顺式-Pd(SiMePh 2)2(CN t Bu)2,而不是有效的催化剂,平面四核钯簇对于烯烃和炔烃(包括位阻三和四取代的烯烃)的氢化是有效的催化剂。
Silylene-transfer reactions of cyclic organosilanes induced by phenanthraquinone triplet
2a–b. Since the photolysis of PQ with 1a–b in the presence of CCl4 gives dichlorooligosilanes, intermediacy of oligosilanyl radicals is highly probable. The quenching rate constant kq of 3PQ* by cyclic organosilane 1b has been determined by laser flashphotolysis. In a mixed solvent of CH3CN and CH2Cl2, 3PQ* is readily quenched by the addition of 1b with the formation of PQ radical anion. On the other
Reactions of a series of peralkylcyclopolysilanes with iodine were found to proceed via second-order kinetics. Rate constants show that, in general, the smaller rings react faster than larger rings. Values of the activation parameters, Ea and ΔG\eweq, decreased with the decreasing ring size and are parallel with those of the oxidation potentials and of the lowest transition energies.
研究发现,一系列全烷基环多硅烷与碘的反应是通过二阶动力学进行的。速率常数表明,一般来说,较小的环比较大的环反应更快。活化参数 Ea 和 ΔG\eweq 的值随着环尺寸的减小而减小,与氧化电位和最低转变能的值平行。
Photo-induced silylene-transfer reactions of cyclic organosilanes to phenanthraquinone
Cophotolysis of cyclic organosilanes 1–4 with phenanthraquinone
gave silylene insertion products via radical displacement at the
silicon atoms of organosilanes by the photochemically excited
phenanthraquinone.
Photolysis of cyclotetrasilanes. Remarkable dependence on molecular structure
作者:Haruo Shizuka、Kazuyuki Murata、Yasushi Arai、Kenichi Tonokura、Hideaki Tanaka、Hideyuki Matsumoto、Yoichiro Nagai、Greg Gillette、Robert West
DOI:10.1039/f19898502369
日期:——
at 415 nm at 77 K. For the peralkylcyclotetrasilanes 3 and 4 having bent structures, photolysis occurs to give the corresponding silylene and cyclotrisilane at 293 K, but not in MP glass at 77 K. These photolyses originate from the excited singlet state (S1), judging from a rapid build-up of the transient absorption after pulsing. Transient peaks for diisopropylsilylene (S3) and t-butylmethylsilylene