Herein, we report the first set of pincer complexes 1 and 2 with the general formula [Ru(CNC)(PPh₃)₂Cl]Cl having a protic- and classical-NHC in the same molecule and nearly identical environments. Deprotonation of the protic-NHC complex 2 with one equivalent of base leads to the formation of anionic-NHC complex 2′. These complexes allow a direct comparison of protic- and anionic-NHCs with the classical-NHC ligand. A comparison of the molecular structure indicated that the metal carbene bond length trend is anionic-NHC > protic-NHC > classical-NHC. The electrochemical investigation revealed the electron donation tendency is classical-NHC > protic-NHC and anionic-NHC > protic-NHC. Cooperation between the metal and the ligand is indicated by the reaction of 2′ with H₂ gas at 1 atm pressure and 110 °C to give the Ru-hydride complex 3.

中文翻译：

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单个 [Ru(CNC)(PPh3)2Cl]Cl 钳形配合物中的质子或阴离子 NHC 与经典 NHC：结构和电子性质以及异解 H2 分裂的直接比较

在此，我们报道了第一组钳配合物1和2，通式为[Ru(CNC)(PPh ₃ ) ₂ Cl]Cl，在相同的分子和几乎相同的环境中具有质子-和经典-NHC。用一当量的碱对质子-NHC 络合物2进行去质子化，形成阴离子-NHC 络合物2'。这些配合物允许将质子和阴离子 NHC 与经典 NHC 配体进行直接比较。分子结构比较表明，金属卡宾键长趋势为阴离子-NHC > 质子-NHC > 经典-NHC。电化学研究表明电子给体趋势为经典-NHC>质子-NHC和阴离子-NHC>质子-NHC。金属和配体之间的合作通过2'与H ₂气体在1atm压力和110℃下反应得到Ru-氢化物配合物3来表明。