The trimesitylsilylium cation
The trimesitylsilylium cation
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DOI：
10.1002/anie.199704001
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发表时间：
1997-03-03
期刊：
影响因子：
--
通讯作者：
Zhao, Y
中科院分区：
文献类型：
--
作者：
Lambert, JB;Zhao, Y
三配位的硅离子R， Si+，至今未见报道。最广泛接受的确定硅性质的标准是* Si的化学位移和从晶体学中获得的表明三配位和平面性的适当结构参数。我们用四（五氟苯）硼酸盐阴离子（TPFPB）和Reed用各种碳硼烷阴离子[31]最接近这种带有烷基的物种。在0f6 ('~ Si)= 90-115范围内观察到化学位移，C-Si-C角为114-117”。31三配位的理想角度是120”，根据气相的计算，这些烷基子物质的化学位移预计为6= 350-380。[~ 1] Reed等人指出，超出硅的范德华半径的非特异性溶剂化可能会显著降低化学位移。他们认为，迄今为止观测到的最佳物种具有36-52%的硅离子~特征。三配位硅的高亲电性是其强烈的配位动力学驱动的原因。的计算
No tricoordinated silylium ion, R, Si+, has been reported to date."] The most widely accepted criteria for determining silylium character are the*'Si chemical shift and suitable structural parameters obtained from crystallography that indicate tricoordination and planarity. The closest approaches to such a species with alkyl groups have been our work [2] with the tetrakis (pentafluoropheny1) borate anion (TPFPB) and Reed's work [31 with various carborane anions. Chemical shifts in the range 0f6 ('~ Si)= 90-115 and C-Si-C angles of 114-117" were observed.['. 31 The ideal angle for tricoordination is 120" and, according to calculations for the gas phase, chemical shifts of 6= 350-380 are expected for these alkyl sub~ tituents.[~ 1 Reed et al. noted that nonspecific solvation beyond the van der Waals radius of silicon may significantly lower the chemical shift. In their opinion, the optimal species observed to date have 36-52% silylium ion~ haracter.'~] The high electrophilicity of tricoordinate silicon is responsible for its strong kinetic drive to coordinate. Calculations by