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。
AN ALTERNATIVE ROUTE TO PERALKYLCYCLOPOLYSILANES: THE REACTION OF 1,2-DICHLOROTETRAALKYLDISILANES WITH LITHIUM
The reaction of 1,2-dichlorotetraalkyldisilanes, Cl(R1R2Si)2Cl (R1=R2=iPr; R1, R2=iPr, Me; R1, R2=Me3SiCH2, Me; R1, R2=tBuCH2, Me; R1, R2=tBu, Me), with an excess amount of lithium in tetrahydrofuran gave the corresponding peralkylcyclopolysilanes, [R1R2Si]n (n=4–5), under mild conditions.
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
Novelperalkylcyclotetrasilanes of the type (R1R2Si)2(R1= R2= ButCH2, R3= R4= Pri; R1= R2= ButCH2, R3= But, R4= Me) were obtained by co-condensation of two 1,2-dichlorotetra-alkyldisilanes with Li; the structure of the tetraisopropyltetraneopentylcyclotetrasilane (1), determined by X-ray crystallography, is folded with a large dihedral angle.
所述类型的新颖peralkylcyclotetrasilanes(R 1 - [R 2 Si)的2(R 1 = R 2 =卜吨CH 2,R 3 = R 4 = PR我; R 1 = R 2 =卜吨CH 2,R 3 =卜吨,通过将两个1,2-二氯四烷基二硅烷与Li共缩合得到R 4 = Me);通过X射线晶体学测定的四异丙基四戊基戊基环四硅烷(1)的结构以大的二面角折叠。
Sensitised (electron-transfer) photochemical reactions of cyclopolysilanes, (R<sup>1</sup>R<sup>2</sup>Si)<sub>n</sub>(n= 3 or 4), in a polar, nucleophilic solvent; electron donating nature of cyclopolysilanes (n= 3–7)
Irradiation (<390 nm) of cyclopolysilanes, (R1R2Si)n(n= 3 or 4), in a mixed solvent (EtOH-MeCN-cyclo-C6H12), with 9,10-dicyanoanthracene as sensitiser, gave the corresponding α-ethoxy-ω-hydropolysilanes resulting from ring-opening addition of ethanol to the polysilanes; a mechanism involving facile electron transfer from the polysilanes is proposed.
在混合溶剂(EtOH-MeCN-cyclo-C 6 H 12)中,用9,10-二氰基蒽作为敏化剂辐照(R 1 R 2 Si)n(n = 3或4 )的环聚硅烷(<390 nm),得到由乙醇开环加成到聚硅烷中而得到的相应的α-乙氧基-ω-氢聚硅烷。提出了一种涉及从聚硅烷容易地进行电子转移的机理。