Optical properties of pyrrolyl-substituted polysilanes
摘要:
Pyrrolyl-substituted polysilanes were synthesized in the present study. The pyrrolyl rings directly attached to the Si conjugated main chains with Si-N bonds. Poly(alkylpyrrolylsilane) and poly(phenylpyrrolylsilane) showed a chromophore which is attributed to sigma-sigma* transition in the conjugated system associated with near-UV fluorescence. However, a strong photoluminescence band was observed at 450-500 mn other than the near-UV photoluminescence for the polysilanes. The luminescence is due to the energy relaxation from sigma* to an inter-band level produced by sigma-pi mixing between main chain sigma-conjugated system and pyrrolyl groups as suggested by theoretical calculations. Transient spectroscopy of the polysilanes was also carried out showing a new chromophore at the vis-IR region (800 nm) other than near-UV (300-400 nm) and IR (similar to 2000 nm) absorption bands typically observed for alkyl- and phenyl-substituted polysilanes. It also supports the presence of the mid-gap level in the pyrrolyl-substituted polysilanes. (C) 2000 Elsevier Science S.A. All rights reserved.
Palladium-Catalyzed Synthesis of <i>N</i>-Vinyl Pyrroles and Indoles
作者:Mohammad Movassaghi、Alison E. Ondrus
DOI:10.1021/jo051450i
日期:2005.10.1
azaheterocycles with vinyl triflates is described. Cyclic and acyclic vinyl triflates along with nonnucleophilic azaheterocycles were found to be substrates for this palladium-catalyzed synthesis of N-vinyl pyrrole and indole derivatives.
Bulky Cyclometalated Ruthenium Nitrates for Challenging
<i>Z</i>
‐Selective Metathesis: Efficient One‐Step Access to α‐Oxygenated
<i>Z</i>
‐Olefins from Acrylates and Allyl Alcohols
作者:Yan Xu、Quan Gan、Adrian E. Samkian、Jeong Hoon Ko、Robert H. Grubbs
DOI:10.1002/anie.202113089
日期:2022.1.21
metathesis is the lack of a widely applicable method that converts feedstock allyl alcohols and acrylates to valuable α-oxygenated Z-olefins. Here, enabled by bulky cyclometalated Ru-nitrate catalysts whose syntheses were newly unlocked, Z-selective metathesis between terminal olefins could now be used to access Z-allyl alcohols, Z-alkenyl esters, and Z-alkenyl acids in high yields and >20 : 1 Z : E selectivity
烯烃复分解的一个持久挑战是缺乏将原料烯丙醇和丙烯酸酯转化为有价值的α-氧化Z-烯烃的广泛适用的方法。在这里,通过新解锁合成的庞大的环金属化硝酸钌催化剂,末端烯烃之间的Z选择性复分解现在可以用于以高产率和 >20 : 1 Z : E选择性。
作者:Yan Xu、Jonathan J. Wong、Adrian E. Samkian、Jeong Hoon Ko、Shuming Chen、K. N. Houk、Robert H. Grubbs
DOI:10.1021/jacs.0c11334
日期:2020.12.16
cyclometalated ruthenium catalysts with bulky N-heterocycliccarbene (NHC) ligands. Superior reactivity and stereoselectivity are realized for the first time in this challenging transformation, allowing streamlined access to an important class of cis-Michael acceptors from readily available feedstocks. The kinetic preference for cross-metathesis is enabled by a pivalate anionic ligand, and the origin
通过使用具有庞大 N-杂环卡宾 (NHC) 配体的新型环金属化钌催化剂,开发了丙烯酰胺和普通末端烯烃之间的高效 Z 选择性交叉复分解。在这一具有挑战性的转化中首次实现了卓越的反应性和立体选择性,允许从现成的原料中简化获得一类重要的顺式迈克尔受体。交叉复分解的动力学偏好是由新戊酸盐阴离子配体实现的,这种效应的起源通过密度泛函理论计算得到阐明。
Regioselective Electrophilic Substitution and Addition Reactions at an N-Coordinated Pyrrolyl Ligand in (PMe<sub>2</sub>Ph)<sub>3</sub>Cl<sub>2</sub>Re(NC<sub>4</sub>H<sub>4</sub>)
作者:M. Rakowski DuBois、Lisa D. Vasquez、L. Peslherbe、B. C. Noll
DOI:10.1021/om9900216
日期:1999.5.1
The reaction of excess pyrrolyllithium with mer-(PMe2Ph)3ReCl3 leads to the formation of the air-stable product mer-(PMe2Ph)3Cl2Re(NC4H4) (1), which has been characterized by spectroscopic techniques and by an X-ray diffraction study. Complex 1 reacts with electrophiles to form new Re(III) complexes with regioselectively substituted pyrrolyl ligands. For example, reaction with 1 equiv of N-chlorosuccinimide
过量pyrrolyllithium与反应聚体- (PME 2 PH)3个RECL 3个通向空气稳定产物的形成聚体- (PME 2 PH)3氯2的Re(NC 4 H ^ 4)(1),其一直以光谱技术和X射线衍射研究为特征。配合物1与亲电试剂反应形成具有区域选择性取代的吡咯基配体的新Re(III)配合物。例如,与1当量的N反应-氯琥珀酰亚胺与3-氯吡咯基配体形成络合物,而与过量试剂反应生成3,4-二氯吡咯基和2,3,4-三氯吡咯基络合物。通过1 H NMR数据确定了反应的区域化学,并通过以下方法确认了二溴化产物(PMe 2 Ph)3 Cl 2 Re(3,4-NC 4 H 2 Br 2)(5)的结构。 X射线衍射。后处理(PMe 2 Ph)3 Cl 2 Re(3-NC 4 H 3 Me)(1与三氟甲磺酸甲酯反应)(6),然后使6与三氟甲磺酸甲酯进一步反应,得到(PMe 2 Ph)3 Cl 2 Re(3
Nucleophilic Substitution of η<sup>5</sup>-Pyrrolyl Ligands in Ruthenium(II) Complexes
作者:M. Rakowski DuBois、K. G. Parker、C. Ohman、B. C. Noll
DOI:10.1021/om9700268
日期:1997.5.1
pyrrolyl ligand has been characterized in some cases, and protonation of the substituted pyrrole complex led to isolation of the free substituted pyrrole with recycling of the rutheniumcomplex. The nucleophilic substitutions are sensitive to the electronic features of the supporting ligands in the complex and to the strength of the nucleophiles.
的RuCl的反应2(PPH 3)3与所述吡咯基复合物(NC的形成pyrrolyllithium结果4 ħ 4)的RuCl(PPH 3)2,1,已特征在于X射线衍射研究。结构确认η 5为吡咯配体η-键接模式。配体取代反应1导致相关η的简便合成5吡咯基钌络合物与其它suppporting配体。PET的反应3衍生物(NC 4 H ^ 4)RUX(PET 3)如图2所示,X = Cl和I,用芳基锂和烷基锂试剂导致吡咯基配体的亲核取代,同时氢转移到金属离子上,形成(2-RNC 4 H 3)RuH(PEt 3)2。可以在氯化溶剂中将氢化物产物转化为相应的氯化物衍生物,以及络合物(2-PhNC 4 H 3)RuCl(PEt 3)2已经在结构上得到了表征。在某些情况下,已经表征了在配位的吡咯基配体上的第二次亲核取代反应,并且取代的吡咯配合物的质子化导致游离取代的吡咯的分离以及钌配合物的再循环。亲核取代对复