Low-valent Alkaline Earth Metal Complexes: Synthesis, Structure and Reactivity

低价碱土金属配合物：合成、结构和反应性

• 批准号: 491060547
• 负责人: Professor Dr. Sjoerd Harder
• 金额: --
• 依托单位: Lehrstuhl für Anorganische und Metallorganische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/491060547?language=en
• 关键词: Low; valent; Alkaline; Earth; Metal

The serendipitous discovery of the first Zn(I) complex, Cp*ZnZnCp*, has stimulated research activities in low-valent s-block metals chemistry. This led in 2007 to discovery of the first Mg(I) complexes in the form of (BDI)MgMg(BDI), a compound class that received enormous attention and was found to be a versatile reducing agent in chemistry (BDI = -diketiminate ligand). Apart from rare Be(0) or Be(I) species and a Ca(I) complex, there are hitherto no examples for (BDI)AeAe(BDI) complexes of the heavier alkaline earth (Ae) metals Ca, Sr and Ba. Our attempts to isolate a (BDI)CaCa(BDI) complex resulted in 2e-reduction of either the aromatic solvent or N2 and formation of (BDI)Ca(arene)Ca(BDI) or (BDI)Ca(N2)Ca(BDI) complexes. Theoretical analyses in cooperation with Frenking (Marburg) showed that d-orbitals on Ca play an essential role in N2 activation. The key to isolation of the Ca-N2 complex is a superbulky -diketiminate ligand that, due to 3-pentyl substituents, enables use of alkane solvents. An even bulkier BDI ligand was used in an effort to cleave the Mg-Mg bond in (BDI)MgMg(BDI) which would result in a highly reactive, hitherto unknown, (BDI)Mg● radical. This attempt led to isolation of a unique (BDI)MgˉNa+ complex in which the zerovalent Mg center carries a formal charge of -1. This new class of magnesyl sodium complexes features an electron-rich Mg center and displays reactivity that is a complete opposite of that of common Mg complexes with positively charged Mg2+ centers.Project aims:1) Deepening our knowledge on bonding in an extended series of (BDI)Ca(arene)Ca(BDI) and (BDI)Ca(N2)Ca(BDI) complexes using spectroscopic methods (NMR, EPR and Calcium Valence-to-Core X‑ray Emission Spectroscopy studies) and theory (partially in collaboration). Our main interest is the importance of d-orbitals in bonding.2) Extending this chemistry to the heavier Ae metals Sr and Ba by design of bulkier ligands (L) and attempts to isolate LAeAeL, the original target of our studies. 3) Studying arene or N2 functionalization and the extreme redox-reactivity of LAe(arene)AeL, LAe(N2)AeL and LAeAeL complexes.4) Isolation of LMg● radicals using superbulky ligands. 5) Investigating the reactivity of the new compound class (BDI)MgˉNa+ with nucleophilic Mg centers that is currently a no-man’s land. 6) Developing a general route to LAeˉM+ complexes for the heavier Ae metals Ca, Sr and Ba. 7) Use the (BDI)MgˉNa+ reagent to create Mg-metal bonds following a salt metathesis route with MXn (X = halide, M = s-, p- or d-block metal). 8) Theoretical analysis of new complexes with DFT, NBO and AIM methods.We aim to run the project with two PhD students and forecast an output of 8-10 full papers which will likely be published in high-impact journals.

第一个Zn(I)配合物Cp*ZnZnCp*的偶然发现，刺激了低价s-嵌段金属化学的研究活动。这导致在2007年发现了第一个以（BDI）MgMg（BDI）形式的Mg(I)配合物，这类化合物受到了极大的关注，并被发现是化学上的多功能还原剂（BDI =-二氯基酸盐配体）。除了稀有的Be(0)或Be(I)种和Ca(I)配合物外，迄今为止还没有较重的碱土（Ae）金属Ca， Sr和Ba的(BDI) - AeAe（BDI）配合物的例子。我们试图分离一种（BDI）CaCa（BDI）配合物，结果导致芳香溶剂或N2的e还原，形成（BDI）Ca（芳烃）Ca（BDI）或（BDI）Ca(N2)Ca（BDI）配合物。与Frenking （Marburg）合作的理论分析表明，Ca上的d轨道在N2活化中起重要作用。分离Ca-N2配合物的关键是一个超大体积的-二酮酸配体，由于3-戊基取代基，可以使用烷烃溶剂。一个体积更大的BDI配体被用来切割（BDI）MgMg（BDI）中的Mg-Mg键，这将导致一个高活性的，迄今为止未知的（BDI）Mg●自由基。这一尝试导致了一个独特的（BDI）Mg - Na+配合物的分离，其中零价Mg中心带-1形式电荷。这种新型镁基钠配合物具有富电子的Mg中心，其反应活性与带正电的Mg2+中心的普通Mg配合物完全相反。项目目标：1)利用光谱学方法（核磁共振、EPR和钙价核X射线发射光谱研究）和理论（部分合作）加深我们对一系列（BDI）Ca（芳烃）Ca（BDI）和（BDI）Ca(N2)Ca（BDI）配合物成键的了解。我们主要感兴趣的是d轨道在成键中的重要性。2)通过设计体积较大的配体(L)将这种化学反应扩展到较重的Ae金属Sr和Ba，并试图分离laeel，这是我们研究的最初目标。3)研究LAe（芳烃）AeL、LAe(N2)AeL和LAeAeL配合物的芳烃或N2功能化和极端氧化还原反应性。4)利用超大体积配体分离LMg●自由基。5)研究新化合物类（BDI）Mg - k - Na+与亲核的Mg中心的反应性，这是目前的一个无人区。6)为较重的Ae金属Ca， Sr和Ba建立LAe - M+配合物的一般途径。7)使用（BDI）Mg - M - Na+试剂与MXn （X =卤化物，M = s-， p-或d-嵌段金属）的盐分解途径建立Mg-金属键。8)用DFT、NBO和AIM方法对新型配合物进行理论分析。我们的目标是与两名博士生一起运行该项目，并预计将在高影响力期刊上发表8-10篇完整论文。