Rhombimines, macrocyclic tetraimines, have been obtained by the condensation of enantiomerically pure trans- 1,2-diamino-cyclohexane with aromatic dialdehydes connected by a one-atom bridge. The efficiency of the cyclocondensation is dependent upon the nature of the dialdehyde bridge atom: low selectivity was observed and rationalized by computational analysis for sp(2) hybridized bridge atoms. Unusual triple-split exciton Cotton effects were measured and calculated for highly symmetrical, tetrachromophoric rhombimines. (c) 2007 Elsevier Ltd. All rights reserved.
[EN] NOVEL ORGANOSILICON COMPOUND, NOVEL CROSSLINKING AGENT, CURABLE COMPOSITION, PREPREG, MULTILAYER BODY, METAL-CLAD LAMINATE AND WIRING BOARD<br/>[FR] NOUVEAU COMPOSÉ D'ORGANOSILICIUM, NOUVEL AGENT DE RÉTICULATION, COMPOSITION DURCISSABLE, PRÉIMPRÉGNÉ, CORPS MULTICOUCHE, STRATIFIÉ À REVÊTEMENT MÉTALLIQUE ET CARTE DE CÂBLAGE<br/>[JA] 新規な有機ケイ素化合物、新規な架橋剤、硬化性組成物、プリプレグ、積層体、金属張積層板および配線基板
[EN] NOVEL ORGANOSILICON COMPOUND, NOVEL CROSSLINKING AGENT, CURABLE COMPOSITION, PREPREG, LAMINATE, METAL-CLAD LAMINATED BOARD, AND WIRING BOARD<br/>[FR] NOUVEAU COMPOSÉ D'ORGANOSILICIUM, NOUVEL AGENT DE RÉTICULATION, COMPOSITION DURCISSABLE, PRÉIMPRÉGNÉ, STRATIFIÉ, CARTE STRATIFIÉE REVÊTUE DE MÉTAL ET CARTE DE CÂBLAGE<br/>[JA] 新規な有機ケイ素化合物、新規な架橋剤、硬化性組成物、プリプレグ、積層体、金属張積層板および配線基板
Transmission of electronic effects via a SiMe2 spacer in 4-mono- and 4,4′-disubstituted diphenyldimethylsilanes: 29Si and 13C NMR spectroscopy and PM3 semi-empirical calculations
作者:Cornelis A. van Walree、Xavier Y. Lauteslager、Andreas M.A. van Wageningen、Jan W. Zwikker、Leonardus W. Jenneskens
DOI:10.1016/0022-328x(95)05473-3
日期:1995.6
13C NMR studies were performed on series of 4-substituted phenyltrimethylsilanes and 4-substituted and 4,4′-disubstituted diphenyldimethylsilanes. Within each series linear relationships are found between the chemicalshifts and (a) the Hammett substituentconstants σp and (b) the PM3-calculated total atomic charges. It is inferred that the SiMe2 σ-type spacer weakly mediates substituenteffects in
对一系列4-取代的苯基三甲基硅烷和4-取代的和4,4'-二取代的二苯基二甲基硅烷进行了约29 Si和13 C NMR研究。在每个系列的线性关系被化学位移和(a)的哈米特取代基常数之间发现σ p和(b)的PM3计算总原子电荷。据推断,所述森达2 σ型分隔弱介导通过键偏振机构处于基态的取代基的影响。与4-取代的和4,4'-二取代的二苯基甲烷的可用数据进行的比较表明,SiMe 2基团比CH 2基团更好地传递电子效应。