Exploring and Exploiting Novel Unsupported TM-M' Heterobimetallic Complexes

该项目建立在Whittlesey小组最近的工作基础上，该小组已经产生了新的杂金属配合物，其特征是过渡金属（TM）和主族金属M' （M' = Zn/ in /Ga/Li/Mg）之间的无支撑键。杂双金属配合物将富e的晚期过渡金属中心与缺e的M'伴侣结合在一起是有吸引力的，因为这可能在催化反应中赋予两种截然不同（可能互补）的活性。虽然国际上已经在设计具有催化活性的TM-M‘系统上付出了很多努力，但在所有这些情况下，缺乏三羧基的M’中心都嵌入在配体支架中。这降低了tm1和M′的配位不饱和水平，使得基本上不可能区分合作效应是(i) tm和M′在直接激活底物中的作用，还是（ii） M′间接作用（一个“花哨的”配体！）来调节tm中心的性质，所有的反应性都发生在tm中心。因此，我们的系统为这一化学研究领域提供了一种新的方法。在我们的一个例子中，有一个Ru- zn键，Ru和zn中心的配位不饱和导致了显著的化学反应活性（H2活化，硼烷的脱氢偶联），并且在初步的概念证明结果中，催化烯烃加氢。现在，我们将探索这些单负载TM-M杂双金属配合物在小分子的化学计量和催化活化方面的全部潜力。最初的目标将是全面研究催化烯烃加氢，以确定催化剂效率，底物范围(例如。“小”vs。“体积庞大”，末端与内部C=C键)和化学选择性（例如，C=C与C=O键的还原）。我们的目标是确定TM/M组合的限制，因为这对于在更广泛的意义上展示我们的无支持债券方法的可行性至关重要。这将涉及(i) M'及其上的取代基的变化，（ii） TM上的支撑配体（例如n -杂环碳烯（NHCs）和膦（PR3））， （iii） TM前体(例如。改变[俄文(NHC) 2 (CO) H] +[俄文(NHC) 2 (PR3) 2 H] +[俄文(P-O-P) (PR3) H] +;LnRu转变为[Pt（NHC)2H]+, [Ir(NHC)2H2]+）。实验工作将通过与Heriot-Watt大学的stuart Macgregor教授合作的计算得到进一步的支持，我们还将通过与巴斯大学化学系的Jonathan Williams教授合作，利用TM和M‘ in away的不同性质，利用M’的刘易斯酸度来协调Lewis碱和TM，从而实现底物活化。该项目对博士生来说是理想的，可以培养操作空气敏感材料的技能，学习催化原理，并接触现代光谱和表征技术（核磁共振光谱，x射线晶体学）。此外，开发新的杂双金属化学体系的目标领域是世界范围内的研究热点。因此，学生将有机会接触到模型无机/有机金属化学领域的顶尖研究人员。

The project builds upon recent work in the Whittlesey group that has led to the generation of novel heterobimetalliccomplexes which feature unsupported bonds between a transition metal (TM) and a main group metal M' (M' = Zn/In/Ga/Li/Mg). Heterobimetallic complexes that combine an e--rich late transition metal centre with an e--deficient M'partner are attractive in that may confer two very different (potentially complementary) activities in catalytic reactions.While much international effort has gone into designing catalytically active TM-M' systems, in all of these cases, thee--deficient M' centre is embedded in a ligand scaffold. This reduces the level of coordinative unsaturation at both TMand M', and makes it essentially impossible to differentiate cooperative effects from being (i) the action of both theTM and M' in directly activating a substrate or (ii) M' acting indirectly (a 'fancy' ligand!) to tune the properties of theTM centre, where all the reactivity occurs. Our systems therefore offer a new approach to this area of chemicalresearch. In one of our examples where there is a Ru-Zn bond, the coordinative unsaturation of the Ru and Zncentres results in remarkable stoichiometric reactivity (H2 activation, dehydrocoupling of boranes) and, in apreliminary proof of concept result, catalytic alkene hydrogenation. We will now explore the full potential of theseunsupported TM-M' heterobimetallic complexes for both the stoichiometric and catalytic activation of small molecules.Initial targets will be to fully investigate catalytic alkene hydrogenation to establish catalyst efficiency, substrate scope(e.g. 'small' vs. 'bulky', terminal vs internal C=C bonds) and chemoselectivity (e.g. reduction of C=C vs C=O bonds).We will them aim to establish the limits of the TM/M' combination, as this is vital for showing the viability of ourunsupported bond methodology in a broader sense. This will involve variation of (i) both M' and the substituents on it,(ii ) the supporting ligands on TM (e.g. N-heterocyclic carbenes (NHCs) and phosphines (PR3)), (iii) the TM precursor(e.g. change of [Ru(NHC)2(CO)H]+ to [Ru(NHC)2(PR3)2H]+, [Ru(P-O-P)(PR3)H]+; change of LnRu to [Pt(NHC)2H]+, [Ir(NHC)2H2]+). The experimental work will be further supported by calculations in collaboration with ProfessorStuart Macgregor at Heriot-Watt University, and we will also aim to exploit the disparate natures of TM and M' in away that exploits the Lewis acidity of M' to coordinate a Lewis base and the TM to bring about substrate activationthrough collaboration with Professor Jonathan Williams here in chemistry at Bath. The project is ideal in nature for aPhD student to develop skills in the manipulation of air-sensitive materials, learn the principles of catalysis and gainexposure to modern spectroscopic and characterisation techniques (NMR spectroscopy, X-ray crystallography).Moreover, the target area to develop novel chemistry of heterobimetallic systems is a topic of worldwide researchinterest. Thus, the student will receive exposure to leading researchers in model inorganic/organometallic chemistry.