非平面分子内电荷转移离子配合物的合成及其光物理性质

以N-乙烯基咔唑三羰基铬为模板化合物, 选用丙烯基阳离子取代其中一个羰基配体, 合成了一种新型非平面分子内电荷转移有机金属配合物. 通过元素分析、红外、核磁共振确定了配合物的组成和结构, 电子吸收和荧光光谱结果表明配合物的光物理行为可通过配体取代调控．运用双光束前向简并四波混频(DFWM)的方法, 测试了配合物及配体的三阶非线性效应, 同时探讨了金属配位和配体取代对其的影响.     

N-(2-溴乙基)咔唑与N-乙烯基咔唑的气相HeI紫外光电子 能谱与电子结构研究

首次报道了N-(2-溴乙基)咔唑和N-乙烯基咔唑的气相HeI紫外光电子能谱(UPS),借助于Gaussian94采用RHF/6-31G基组优化几何构型,并用RHF/6-31G^*基组计算分子轨道及能级.在对咔唑和N-烷基咔唑系列分子UPS电离能变化规律研究的基础上,对这2个分子的UPS谱带给予指认,并讨论其电子结构.结果表明N-(2-溴乙基)咔唑的UPS谱与N-烷基咔唑的不同之处是在10.295,10.540eV处出现2个Br原子的孤对轨道;N-乙烯基咔唑的UPS谱带与咔唑的相比,电离能变化的特殊性说明乙烯基与咔唑环共平面。     

N-(2-溴乙基)咔唑与N-乙烯基咔唑的气相HeI紫外光电子能谱与电子结构研究

首次报道了N-(2-澳乙基)咔唑和N-乙烯基咏唑的气相Hel紫外光电子能谱(UPS),借助于Gaussian 94采用RHF/6-3lG基组优化几何构型,并用RHF/6-31G基组计算分子轨道及能级.在对咔唑和N-烷基咔唑系列分子UPS电离能变化规律研究的基础上,对这2个分子的UPS谱带给予指认,并讨论其电子结构.结果表明N-(2-溴乙基)咔唑的UPS谱与N-烷基咔唑的不同之处是在10.295,10.540Ve处出现2个Br原子的孤对轨道;N-乙烯基咔唑的UPS谱带与咔唑的相比,电离能变化的特殊性说明乙烯基与咔唑环共平面.     

N-乙烯基咔唑引发丙烯腈光聚合研究

N-乙烯基咔唑(VCz)是一个正性单体,双键上电荷密度较大,容易在顺丁烯二酸酐、反丁烯二酸二乙酯、丙烯腈(AN)等负性单体诱发下进行正离子聚合,以及与这些单体进行自发的交替共聚合。从结构上看,它又是一个三级胺,氮原子连两个苯基和一个乙烯基,所以电荷密度较大,是一个强电子给体。从芳     

N-乙烯基咔唑的光聚合

N-乙烯基咔唑的三氯甲烷溶液经光照后可以获得聚N-乙烯基咔唑,这一结论已经通过荧光光谱和NMR谱得到证实,产率很高可达70％。又通过荧光淬灭实验证实:这一反应首先在光照下形成激基复合物,由激基复合物分解产生自由基而引发N-乙烯基咔唑的聚合,此外,本文还研究了光强、N-乙烯基咔唑的浓度和光照时间对产率的影响。     

8-丙烯酰氧喹啉及其聚合物与四溴化碳双组分体系敏化的丙烯腈光聚合

我们曾报道过8-丙烯酰氧喹啉本身在光照下可以聚合;8-丙烯酰氧喹啉(AQ)及其聚合物(PAQ)的喹啉环上的氮原子可以和双键缺电子单体如丙烯腈(AN)在紫外光下能形成激基复合物引发AN的光聚合,并且通过荧光分析证明AQ或PAQ还参与AN聚合物链中,含有氮杂环的烯类单体如N-乙烯基咔唑等不仅和缺电子化合物,和一些卤代烷如CCl_4、CBr_4等在激发下也可以形成激基复合物,进而可以引发烯类单体聚     

(乙烯基咔唑-甲基丙烯酸金刚烷酯)共聚物的制备与光致发光性能

以1-金刚烷醇和甲基丙烯酰氯为原料,经酯化反应合成甲基丙烯酸金刚烷酯单体。然后通过甲基丙烯酸金刚烷酯与N-乙烯基咔唑进行共聚反应合成了乙烯基咔唑-甲基丙烯酸金刚烷酯共聚物。采用1H-NMR、FI-IR和元素分析等表征了共聚产物的结构,通过凝胶渗透色谱仪和荧光光谱仪考察了金刚烷基团对共聚物结构与荧光性能的影响。     

高效液相色谱法测定N-乙烯基咔唑的含量

建立了一种操作简单、灵敏度高的N-乙烯基咔唑含量的高效液相色谱测定方法。采用BDS-C18柱,以乙腈∶水=70∶30(体积比)为流动相,流速为1.0mL/min,检测波长为240nm,外标法定量测定N-乙烯基咔唑的含量。N-乙烯基咔唑在0.02～0.2mg/mL范围内呈线性关系,相关系数为0.9999,平均回收率为106.7%,相对标准偏差0.87%。该方法操作简单,灵敏度高,结果准确,适用于N-乙烯基咔唑的含量检测。     

电荷转移聚合

链引发或链增长过程包含有电荷转移的聚合称电荷转移聚合。通常可分两类:一是电子受体(或给体)直接引发烯类单体聚合。典型例子是电子受体四腈基乙烯(TCNE)引发乙烯基咔唑(给电子单体)聚合,或苯胺(电子给体)引     

Lewis酸碱对在聚合中的应用

自从Stephan和Erker两位科学家提出“位阻型(Frustrated)Lewis酸碱对”概念以来,Lewis酸碱对的催化化学得到极大的关注。近年来,人们也发现Lewis酸碱对在催化极性乙烯基单体和内酯单体聚合中有着重要的应用。Lewis酸碱对催化极性乙烯基单体聚合可形成具有高分子量和窄分子量分布的聚合物,而催化活性与所使用的Lewis酸碱对关系密切,最有效的Lewis酸是Al(C₆F₅)₃和B(C₆F₅)₃,Lewis碱是有机磷、氮杂环卡宾和氮杂环卡宾烯和膦腈超强碱,可聚合的单体包括甲基丙烯酸甲酯、γ-甲基-α-亚甲基-γ-丁内酯、α-亚甲基-γ-丁内酯、 丙烯酸正丁酯、 N,N-二甲基丙烯酰胺、 N,N-二苯基丙烯酰胺、 乙烯基磷酸二乙酯、2-乙烯基吡啶、2-异丙烯基-2-氧 NFDA1 唑林以及非对称的极性二乙烯基单体。聚合过程包括:链引发、链增长和链终止。链引发过程是通过Lewis酸、Lewis碱和单体相互作用形成两性离子,链增长是通过双金属活化单体加成方式进行,链终止通过两种途径:1)增长聚合物链中活化的酯氧负离子对相邻酯中羰基碳原子的亲核进攻形成δ-戊内酯;2)增长聚合物链中活化的烯酯碳负离子对倒数第三个酯中羰基碳原子的亲核进攻形成β-酮酸酯。Lewis酸碱对催化内酯单体聚合可形成线形和环状聚合物,所使用的Lewis酸为Zn(C₆F₅)₃、有机铝、氯化铟,Lewis碱为有机胺。     

1H NMR conformational analysis of disubstituted arene tricarbonyl chromium complexes

The positions of conformational equilibrium in disubstituted arene chromium tricarbonyl complexes, i.e. alkylanisole chromium tricarbonyl complexes and alkylbenzoate chromium tricarbonyl complexes, have been determined by ¹H NMR spectroscopy. It has been found that the donor effect is the dominant factor in determining the preferred conformation.     

含乙烯基π-芳烃金属铬羰基配合物的合成

由含有不饱和有机官能团的芳煤与三胺基三羰基铬在温和条件下反应,合成了7个新的具有聚合潜力的π芳烃金属铬羰基配合物,并通过元素分析,IR,UV和1H NMR对其进行了表征。     

Donor and acceptor properties of the chromium tricarbonyl substituent in benzylic and homobenzylic anions, cations, and radicals

Both benzylic cations and anions are strongly stabilized by chromium tricarbonyl complexation, while benzylic radicals are largely unaffected. Density functional theory calculations were performed on primary, secondary, and tertiary benzylic species to explore the effect of substitution on the stabilizing ability of the chromium tricarbonyl moiety. Complexed 1-indanyl species were also examined to elucidate the effect of conformational restraint. It was found that the strong stabilization of benzylic anions and the slight destabilization of benzylic radicals by chromium tricarbonyl are insensitive to skeletal changes. Chromium-complexed benzylic cations, however, are highly sensitive to changes in the organic framework, with increased substitution or constriction of conformational mobility eroding the effect of the metal. 2-Indanyl species were also examined to study the effect of the chromium tricarbonyl fragment on homobenzylic species. It was found that the metal fragment stabilizes distant anions by field and inductive effects and cations by a direct interaction of the metal with the cationic carbon. Homobenzylic radicals, however, do not interact with the chromium tricarbonyl moiety and suffer a slight inductive destabilization.     

Directed regioselective lithiation of (η-arene) chromium tricarbonyl complexes : Regioselective synthesis of anthraquinones and calamenenes

(3-Methoxybenzylalcohol)chromium tricarbonyl (10) and (7-methoxy-1-tetralol)chromium tricarbonyl (12) are selectively lithiated at the 4- and 6-positions, respectively, by treatment with n-BuLi-TMEDA. Since the directed lithiation of the corresponding chromium free arenes normally proceeds at the 2-and 8-positions, complementarily substituted arenes can be prepared by using the chromium tricarbonyl complexes. The difierent position of lithiation is explained by the relative configuration of the chromium tricarbonyl group in the (arene)Cr(CO)₃ and electrostatic factors. Some anthraquinones, 31,36,42, and 7-hydroxycalamenenes, 43, have been synthesized through the stereo- and regioselective introduction of substituents by means of(η⁶-arene)chromium tricarbonyl complexes.     

The tricarbonylchromium template for stereocontrol in radical reactions of arenes

Chromium tricarbonyl complexed aryl aldeyhydes and ketones underwent Sm(II)-promoted radical lactone formation in the presence of alpha,beta-unsaturated esters to produce diastereomerically pure lactones in good yields. The completely diastereoselective lactone formation involves capture of the benzylic ketyl radical by the ester anti to the chromium tricarbonyl moiety. The relative stereochemistry of the lactone and chromium tricarbonyl moieties was proven by X-ray crystallography and supports the proposed mechanism. Enantiopure chromium tricarbonyl complexed arenes afforded single enantiomers when subjected to Sm(II)-promoted radical lactone formation condiditions. The enantio- and diastereomerically pure chromium tricarbonyl complexed lactones were subsequently treated with BF3.OEt2 to generate a mixture of diastereomers via Lewis acid promoted chromium tricabonyl directed cationic rearrangement. The diastereomers were separated and individually decomplexed with I2 to afford both of the corresponding chromium-free enantiomerically pure lactones starting from a single enantiomerically pure chromium tricarbonyl complex.     

Metal arene complexation of polybenzyl: Preparation and methylation

Polybenzyl has been complexed with the chromium tricarbonyl moiety by thermal treatment with chromium hexacarbonyl. The aryl rings of the product were complexed with the chromium tricarbonyl moiety to the extent of 41–63%. Assessment of the degree of complexation was satisfactorily carried out by elemental chromium analysis or by ¹³C-NMR methods which agreed within 5%. GPC was less satisfactory. TGA analysis of the complexed polymers suggested the possibility of cross-linking on thermal treatment. The benzylic groups of the polymer complex were methylated with base and methyl iodide in up to 88% of the complexed arene activated methylene groups. © 1992 John Wiley & Sons, Inc.     

Reaction of phenyl-containing N-substituted 1,3-oxazolidines and 1,3-oxazinanes with triammine(tricarbonyl)chromium

Russian Chemical Bulletin - New heterocyclic compounds with phenyl chromium tricarbonyl substituents were synthesized by the reaction of triammine(tricarbonyl)chromium with phenyl-substituted...     

Catalytic enantioselective cycloadditions: a readily available Diels–Alder catalyst

A highly selective Diels–Alder catalyst has been prepared from a commercially available tetrahydronaphthalene diol. Stereocontrol is enhanced by introduction of a planar chiral arene chromium tricarbonyl group.     

Heterogeneous and homogeneous hydrogenation of styrene and stilbene chromium tricarbonyl complexes

Heterogeneous hydrogenation of the styrene and stilbene chromium tricarbonyl complexes by molecular hydrogen on skeletal nickel and palladium on carbon as catalysts was studied. As compared to styrene and stilbene, their arene chromium tricarbonyl analogs are hydrogenated considerably more slowly, which is related, most likely, to strong adsorption of the π-complexes on the catalyst surface. For the homogeneous hydrogenation of these complexes using a H₂PtCl₆-SnCl₂-LiBr system, styrene and η⁶-styrene chromium tricarbonyl are reduced with a high rate, whereas stilbene and its chromium tricarbonyl complex are hydrogenated very slowly. A possibility of reduction of the unsaturated arene chromium tricarbonyl complexes by sodium borohydride in the presence of cobalt(II) chloride as a catalyst was shown. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 44–47, January, 2007.     

[2+4] Cycloaddition of η6-(styrene)chromium tricarbonyl and conjugated dienes

Cycloaddition of η⁶-(styrene)chromium tricarbonyl to hexa-2,4-diene or cyclopentadiene afford the Diels-Alder adducts with retention of the Cr(CO)₃ group, whereas cyclohexa-1,3-diene undergoes aromatization to give η⁶-(benzene)chromium tricarbonyl. The counter synthesis of these (arene)chromium tricarbonyl derivatives from uncoordinated adducts of the Diels-Alder reaction and chromium hexacarbonyl was carried out.