Umpolung of electrophilic terminal phosphinidene complexes: coordination chemistry to phosphorus and gateway to the chemistry of low-coordinate P-based super-electrophiles

该研究项目的主要目的是开发新的方法来产生新的、高度亲电的低价磷物种，能够激活小分子。研究的起点应该是末端供体稳定的末端，即亲电亚膦络合物(EPC)，即“umgepolte”EPC。应研究它们的结构/反应性关系，重点是磷中心的以下过程：氧化/氧化加成(A)和质子化(B)。在A部分，我们将研究EPC加合物的氧化反应，以合成高度亲电的亚膦氧化物络合物(EPOCs)，以及具有不同极化的E-E‘键的物种的氧化加成反应的途径。在B部分中，我们将端接给电子体EPC加合物与强Brnsted酸(I)或1，1‘-双功能氯膦络合物与氯萃取剂(II)反应。这将打开通向新型质子化内皮祖细胞(PEPC)的大门，而对于它们的反应性来说，重要的是I)和II)中的反应物具有弱配位阴离子(WCA)。这样的PEPC将在小分子活化中进行检测，如二氧化碳、氮气和P4。总而言之，该项目不仅应该导致对非金属元素磷的配位/有机金属化学的新的基本见解，而且还应该创造出温和而强大的新的合成方法。将与A.埃斯皮诺萨(西班牙)密切合作进行理论研究。

Major aim of the research project is to develop new methodologies to generate novel, highly electrophilic low valent phosphorus species, able to activate small molecules. Starting point for the study should be end-on donor-stabilized terminal, electrophilic phosphinidene complexes (EPCs), i.e. "umgepolte" EPCs. Their structure/reactivity relationship shall be studied, focusing on the following processes at the phosphorus centre: oxidation/oxidative addition (A) and protonation (B). In part A we will study oxidation reactions of end-on donor EPC adducts in order to synthesize highly electrophilic phosphinidene-oxide complexes (EPOCs), but also pathways of oxidative addition reactions of species having differently polarized polar E-E’ bonds. In part B we will react end-on donor EPC adducts with strong Brønsted acids (i) or 1,1’-bifunctional chlorophosphane complexes with chloride abstractors (ii). This should open the gateway to novel protonated EPCs (PEPCs), and important for their reactivity is that reactants in i) and ii) possess weakly coordinating anions (WCAs). Such PEPCs will be examined in small molecule activation such as CO2, N2 and P4. In total, the project should not only lead to new fundamental insights into the coordination/ organometallic chemistry of the non-metal element phosphorus, but also create new mild, powerful synthetic methods. Theoretical studies will be performed in close collaboration with A. Espinosa (Spain).