ELECTRONIC AND GEOMETRIC ORIGINS OF THE NON-INNOCENT NATURE OF LIGANDS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者的研究机构。 我们提出了多边缘x射线吸收研究解剖的基本分子细节的非无辜的配位体在配位化合物中的行为。配体的非无辜性质最好的宏观特征是基于配体的反应性，其中中心金属成为旁观者，最常见的是空间骨架，而不是反应位点。在微观上，这转化为富含配体贡献的价轨道（即大配体共价）。我们已经收集了初步的数据，正式Ni（II）/Ni（III）氧化还原对系统支持的钳型配体表示PNP（PNP？= N[2-P（CHMe 2）2-4-甲基苯基]2）的结构，这清楚地证明了我们测量的可行性。我们的数据出乎意料地显示非无辜的行为钳型配体PNP？在有机金属化学和催化的背景下，最初被认为是无辜的辅助。以前，这种行为主要是观察到含硫和氧的配体，如二硫杂环戊烯和儿茶酚。我们首先计划研究两个钳型配体与PCP和PNP的组合物，协调到一系列的第一行过渡金属作为中心金属在其正式的单，二，和三价形式。考虑到磷的还原能力，我们还将研究仅具有氮供体的钳形配体，特别是单阴离子NCN系统C6 H3 [1，3-CH 2NiPr 2]2。这些拟议的研究是一个更大项目的一部分，旨在了解作为3d过渡金属离子（从晚期转移到中期）和配体中杂原子性质的函数的物理化学因素，这些因素可能导致非无辜行为。我们希望为合成化学家建立指导方针，使他们能够先验地预测非无辜的行为。多边缘XAS提供了一种直接探测氧化还原活性物质组成的方法

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We propose multi-edge x-ray absorption studies to dissect the fundamental molecular details of the non-innocent behavior of ligands in coordination compounds. The non-innocent nature of ligands is best characterized macroscopically by ligand-based reactivity, where the central metal becomes a spectator and most often a steric scaffold rather than a reactive site. Microscopically this translates into valence orbitals that are rich in ligand contribution (i.e. large ligand covalency). We have already collected preliminary data for formally Ni(II)/Ni(III) redox couple system supported with a pincer-type ligand denoted PNP (PNP ? = N[2-P(CHMe2)2-4-methylphenyl]2) at the Ni L-, Cl and P K-edges that clearly demonstrate the feasibility of our measurements. Our data unexpectedly show the non-innocent behavior of the pincer-type ligand PNP ? originally thought to be innocent ancillary in the context of organometallic chemistry and catalysis. Previously this behavior was mainly observed for sulfur and oxygen containing ligands, such as dithiolenes and catecholes. We first plan to study two pincer-type ligands with PCP and PNP compositions that are coordinated to a series of first row transition metals as central metals in their formally mono-, di-, and trivalent forms. Given the reducing ability of phosphorus, we will also investigate pincer ligands having only nitrogen donors, specifically the monoanionic NCN system C6H3[1,3-CH2NiPr2]2. These proposed investigations are part of a larger project aiming to understand the physical-chemical factors that can contribute to non-innocent behavior as a function of the 3d transition metal ion (when shifting from late to mid) and the nature of the heteroatom in the ligand. We wish to set up guidelines for synthetic chemists to be able a priori predict non-innocent behavior. The multi-edge XAS provide a direct way to probe the composition of the redox active mole