Cationic Cyclopentadienyl Zinc Complexes with Slipped Triple-Decker and Half-Sandwich Structures
Cationic Cyclopentadienyl Zinc Complexes with Slipped Triple-Decker and Half-Sandwich Structures
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DOI：
10.1002/chem.201102699
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发表时间：
2011-11-01
影响因子：
4.3
通讯作者：
Braun, Beatrice
中科院分区：
文献类型：
--
作者：
Chilleck, Maren A.;Braun, Thomas;Braun, Beatrice
锌化合物的一个迷人的方面是它们的结构多样性。十甲基锌茂[ZnCp* 2]（1; Cp*= C5 Me 5）和相关的锌茂，它们具有取代的β配体，表现出一个β配体以η5（π）模式结合，另一个以η1（π）模式结合的滑移夹心结构。[1，2]相比之下，锌茂[ZnCp 2]在固态下是聚合的。[3]在2004年，Carmona等人描述了十甲基二锌茂[Zn 2Cp * 2]（2）的合成，这是第一个稳定的分子化合物，具有Zn 2 + Zn键和形式+1氧化态的Zn。[4]化合物2可以由1通过用[ZnEt 2]或KH处理来制备。这是由舒尔茨埃塔尔证明的。配合物1和2可以作为刘易斯酸。与强刘易斯碱4-二甲氨基吡啶（dmap）反应得到相应的刘易斯酸碱加合物[ZnCp* 2ACHTUNGTRENNUNG（dmap）]和[Cp* ZnZnCp* ACHTUNGTRENNUNG（dmap）2]。[5]迄今为止，仅报道了有限数量的具有通式[ZnRLn]+（R=烷基）的结构明确的阳离子有机锌化合物。[6-9]在所有情况下，需要存在另外的稳定供体配体L。在螯合配体L的存在下，[ZnR 2]与烷基阴离子发生反应，合成了第一个阳离子配合物[ZnRL]+（L=冠醚或穴醚）。[6]用刘易斯酸BACHTUNGTRENNUNG（C6 F5）3或强布朗斯特酸[HACHTUNGTRENNUNG（OEt 2）2]+[BACHTUNGTRENNUNG（C6 F5）4]在乙醚中处理[ZnR 2]，得到溶剂稳定的[ZnRACHTUNGTRENNUNG（OEt 2）3]+型阳离子。[7]据我们所知，文献中仅提及一个阳离子双金属锌衍生物的实例。提出了[ZnCp'EtACHTUNGTRENNUNG（tmeda）]（Cp'=（3，5-Me 2C 6 H3）CH 2CMe 2ACHTUNGTRENNUNG（C5 H4），tmeda= N，N，N '，N'-四甲基-ACHTUNGTRENNUNG亚乙基ACHTUNGTRENNUNG二胺）与BACHTUNGTRENNUNG（C6 F5）3的反应导致形成[ZnCp'ACHTUNGTRENNUNG（tmeda）]+ ACHTUNGTRENNUNG [BEtACHTUNGTRENNUNG（C6 F5）3] β。[8]后一种化合物的鉴别仅基于NMR光谱提出。所有已知的阳离子锌络合物由于其高度亲电性质而需要弱配位阴离子的存在。[10]本文报道了阳离子三层锌配合物[Zn 2Cp * 3]+ ACHTUNGTRENNUNG [BArF 4][BArF 4= BACHTUNGTRENNUNG（3，5-ACHTUNGTRENNUNG（CF 3）2C 6 H3）4（3），BACHTUNGTRENNUNG（C6 F5）4（4）]的合成。它们可以被认为是{Cp* Zn}+实体的来源。用螯合配体处理3，可以得到新的阳离子双锌衍生物。
One of the fascinating aspects of cyclopentadienyl zinc compounds is their structural diversity. Decamethylzincocene [ZnCp* 2](1; Cp*= C5Me5) and related zincocenes, which have substituted cyclopentadienyl ligands, exhibit a slipped-sandwich structure with one cyclopentadienyl ligand bound in an η5 (π) mode and the other bound in an η1 (π) mode.[1, 2] In contrast, zincocene [ZnCp2] is polymeric in the solid state.[3] In 2004, Carmona et al. described the synthesis of decamethyldizincocene [Zn2Cp* 2](2), which was the first stable molecular compound with a ZnÀZn bond and Zn in the formal+ 1 oxidation state.[4] Compound 2 can be prepared from 1 through treatment with [ZnEt2] or KH. It was shown by Schulz etal. that complexes 1 and 2 can act as Lewis acids. Reactions with the strong Lewis base 4-dimethylaminopyridine (dmap) gave the corresponding Lewis acid–base adducts[ZnCp* 2ACHTUNGTRENNUNG (dmap)] and [Cp* ZnZnCp* ACHTUNGTRENNUNG (dmap) 2].[5] Only a limited number of structurally well-defined cationic organozinc compounds with the general formula [ZnRLn]+(R= alkyl) have been reported so far.[6–9] In all cases, the presence of additional stabilizing donor ligands L is required. The first cationic complexes [ZnRL]+(L= crown ether or cryptand) were synthesized by alkyl anion abstraction from [ZnR2] in the presence of a chelating ligand L.[6] Treatment of [ZnR2] with either the Lewis acid BACHTUNGTRENNUNG (C6F5) 3 or the strong Brønsted acid [HACHTUNGTRENNUNG (OEt2) 2]+[BACHTUNGTRENNUNG (C6F5) 4] À in diethyl ether afforded solvent-stabilized cations of the type [ZnRACHTUNGTRENNUNG (OEt2) 3]+.[7] To the best of our knowledge, there is only one example of a cationic cyclopentadienyl zinc derivative mentioned in the literature. It was suggested that the reaction of [ZnCp’EtACHTUNGTRENNUNG (tmeda)](Cp’=(3, 5-Me2C6H3) CH2CMe2ACHTUNGTRENNUNG (C5H4), tmeda= N, N, N’, N’-tetramethyl-ACHTUNGTRENNUNGethyleneACHTUNGTRENNUNGdiamine) with BACHTUNGTRENNUNG (C6F5) 3 results in the formation of [ZnCp’ACHTUNGTRENNUNG (tmeda)]+ ACHTUNGTRENNUNG [BEtACHTUNGTRENNUNG (C6F5) 3] À.[8] The identity of the latter compound was proposed on the basis of NMR spectroscopy only. All of the known cationic zinc complexes require the presence of a weakly coordinating anion due to their highly electrophilic nature.[10]Herein, the synthesis of the cationic triple-decker zinc complexes [Zn2Cp* 3]+ ACHTUNGTRENNUNG [BArF 4] À (BArF 4= BACHTUNGTRENNUNG (3, 5-ACHTUNGTRENNUNG (CF3) 2C6H3) 4 (3), BACHTUNGTRENNUNG (C6F5) 4 (4)) is reported. They can be considered as a source of a {Cp* Zn}+ entity. New cationic cyclopentadienyl Zn derivatives can be obtained on treatment of 3 with chelating donor ligands.