Ameskal Mohammad, Taakili Rachid, Gulyaeva Ekaterina S, Duhayon Carine, Willot Jérémy, Lugan Noël, Lepetit Christine, Valyaev Dmitry A, Canac Yves
LCC-CNRS, Université de Toulouse, CNRS, 205 route de Narbonne, 31077 Toulouse cedex 4, France.
A. N. Nesmeyanov Institute of Organoelement Compounds (INEOS), Russian Academy of Sciences, 28/1 Vavilov str., GSP-1, B-334, Moscow 119334, Russia.
Inorg Chem. 2023 Dec 11;62(49):20129-20141. doi: 10.1021/acs.inorgchem.3c03025. Epub 2023 Nov 23.
An efficient synthesis of two pincer preligands [PhPCH(R)ImCHCHCHPPh]X (R = H, X = OTf; R = Ph, X = BF) was developed. Subsequent reactions with PdCl and an excess of CsCO led to the formation of highly stable cationic metalated Pd(II) complexes [(,,,)Pd]X exhibiting phosphine, NHC, phosphonium ylide, and σ-aryl donor extremities. The protonation of one of the latter complexes with R = H affords the Pd(II) complex (,,)Pd(MeCN) bearing an unprecedented nonsymmetrical NHC core pincer scaffold with a 5,6-chelating framework. The overall donor properties of this phosphine-NHC-phosphonium ylide ligand were estimated using the experimental ν stretching frequency in the corresponding (,,)Pd(CNBu derivative and were shown to be competitive with the related bis(NHC)-phosphonium ylide and phenoxy-NHC-phosphonium ylide pincers. The presence of a phenyl substituent in the bridge between phosphine and NHC moieties in the metalated complex (,,,)Pd makes possible the deprotonation of this position using LDA to provide a persistent zwitterionic complex [(,,,)Pd] featuring a rare -coordinated phosphonium ylide moiety in addition to a conventional -coordinated one. The comparison of the P and C NMR data for these - and -bound phosphonium ylide fragments within the same molecule was performed for the first time, and the bonding situation in both cases was studied in detail by QTAIM and ELF topological analyses.
开发了两种钳形前配体[PhPCH(R)ImCHCHCHPPh]X（R = H，X = OTf；R = Ph，X = BF）的高效合成方法。随后与PdCl和过量的CsCO反应，生成了高度稳定的阳离子金属化Pd(II)配合物[(,,,)Pd]X，该配合物具有膦、NHC、鏻叶立德和σ-芳基供体端基。其中一种R = H的配合物质子化后得到Pd(II)配合物(,,)Pd(MeCN)，其具有前所未有的不对称NHC核心钳形支架和5,6-螯合框架。利用相应的(,,)Pd(CNBu衍生物中的实验ν伸缩频率估算了这种膦-NHC-鏻叶立德配体的整体供体性质，结果表明其与相关的双(NHC)-鏻叶立德和苯氧基-NHC-鏻叶立德钳形配体具有竞争力。在金属化配合物(,,,)Pd中，膦和NHC部分之间的桥连中存在苯基取代基，这使得使用LDA对该位置进行去质子化成为可能，从而提供一种持久的两性离子配合物[(,,,)Pd]，除了传统的-配位鏻叶立德部分外，还具有罕见的-配位鏻叶立德部分。首次对同一分子内这些-和-键合的鏻叶立德片段的P和C NMR数据进行了比较，并通过QTAIM和ELF拓扑分析详细研究了两种情况下的键合情况。
