Understanding and quantifying the electronic properties of ligands is important both from a fundamental point of view and also for their applications in various branches of chemistry. In this contribution, we present a comparative study on the donor/acceptor properties of 10 different triazolylidene-type mesoionic carbene ligands (MICs), with the aim of investigating and deciphering the effects of substituents on the donor/acceptor properties of such MIC ligands. Data from ⁷⁷Se NMR chemical shifts of the triazoline selones, the ¹J_C-H coupling constants of the corresponding triazolium salts, and the Tolman electronic parameters (TEP) of the Ir-CO complexes are compared and contrasted. The data collected in this work show that the spread of both the TEP and the ¹J_C-H coupling constants is relatively narrow to be able to significantly differentiate between the donor properties of the various MICs. The ⁷⁷Se NMR shifts of the triazoline selones on the other hand show a broad spread, and it is in principle well-suited to understand the π-accepting properties of the MICs as a function of substituents. However, this method can have other complications which are discussed in this work. DFT calculations are presented to spread light on the ⁷⁷Se NMR shifts. Additionally, we present the first example of a Au^I complex with mesoionic triazoline selones, a class of ligands whose utility has remained underexplored in transition metal chemistry.

中文翻译：

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通过介观的硒酸，三唑盐和Ir-羰基-三唑基络合物探测三唑基的电子性质

从基本的观点以及对于它们在化学的各个分支中的应用而言，理解和定量配体的电子性质都是重要的。在此贡献中，我们提出了对10种不同的三唑基亚型中离子卡宾配体（MIC）的供体/受体性质的比较研究，目的是研究和破译取代基对此类MIC配体的供体/受体性质的影响。三唑啉酮¹ J _C-H的⁷⁷ Se NMR化学位移数据比较并对比了相应的三唑鎓盐的偶合常数和Ir-CO络合物的Tolman电子参数（TEP）。在这项工作中收集到的数据表明，TEP和¹ J _C-H耦合常数的分布相对较窄，从而能够显着地区分各种MIC的供体性质。另一方面，三唑啉酮的⁷⁷ Se NMR位移显示出广泛的分布，并且原则上非常适合理解MIC的π接受性质与取代基的关系。但是，此方法可能还会有其他复杂性，在本文中将对此进行讨论。提出了DFT计算以在^77处传播光线Se NMR位移。另外，我们提出了与介电三唑啉丝氨酸的Au ^I络合物的第一个例子，这是一类在过渡金属化学领域仍未得到充分开发的配体。