Pincer-type ligands, complexes, and catalyst design

过渡金属有机金属化学可以说是现代科学的中心领域之一，因为过渡金属络合物在石油化工、医药以及农业和食品工业的化学品的催化有机合成中的应用。NSERC发现基金申请中提出的这项研究解决了几种重要和具有挑战性的均相催化反应类型。(A)部分寻求从天然氨基酸中开发手性PNN配体。我们将合成一系列四种金属(Re、Ru、Os和Ir)的手性PNN钳形配合物，用于极性C=O和C=N键的不对称氢化以及手性醇和胺的生成。这种类型的络合物也可用于酯和酰胺的催化还原。(B)涉及含有中心吡啶(RNHC)片段的新型PCP和PCN卡宾配体的开发。我们的计算数据预测，当形成钳形络合物时，这种配体应该扮演非常强大的电子供体的角色。这些Ru、Os、Rh和Ir的配合物将用于催化碳氢化合物的C-H键和N-H键的活化、脱氢偶联以及脱氢和功能化反应。将探索PCP和PCN钳形卡宾络合物用于氮氢化，以努力加强现有的氨技术，并开发最先进的TM催化剂。建议的研究为培养有机过渡金属化学、主基和有机合成、催化和计算化学方面的本科生和研究生提供了一个极好的机会。

Organometallic chemistry of transition metals (TM) is arguably one of the central areas of modern science owing to the application of TM complexes in catalytic organic syntheses of petrochemicals, pharmaceuticals, and chemicals for agricultural and food industries. The research proposed in this NSERC Discovery grant application addresses several important and challenging types of homogeneously catalyzed reactions. Part (a) seeks to develop chiral PNN ligands from natural amino acids. We will make a family of chiral PNN pincer-type complexes of four metals (Re, Ru, Os, and Ir) for asymmetric hydrogenation of polar C=O and C=N bonds and production of chiral alcohols and amines. Complexes of this type can also be useful for catalytic reduction of esters and amides. Part (b) deals with the development of novel PCP and PCN carbene ligands incorporating a central pyridylidene (rNHC) fragment. Our computational data predict that such ligands should act as exceptionally powerful electron donors when forming pincer-type complexes. These complexes of Ru, Os, Rh, and Ir will be applied in catalytic C-H and N-H bond activation, dehydrogenative coupling, and dehydrogenation and functionalization reactions of hydrocarbons. The PCP and PCN pincer carbene complexes will be explored for nitrogen hydrogenation in an effort to enhance existing ammonia technology and develop new state-of-the-art TM-based catalysts. The proposed research presents an excellent opportunity for training of undergraduate and graduate students in organo-transition metal chemistry, main-group and organic synthesis, catalysis, and computational chemistry.