Carrasco Carlos J, Montilla Francisco, Álvarez Eleuterio, Galindo Agustín
Departamento de Química Inorgánica, Facultad de Química, Universidad de Sevilla, 41012 Sevilla, Spain.
Instituto de Investigaciones Químicas, CSIC-Universidad de Sevilla, Avda. Américo Vespucio 49, 41092 Sevilla, Spain.
Inorg Chem. 2025 Jul 28;64(29):14871-14881. doi: 10.1021/acs.inorgchem.5c01231. Epub 2025 Jul 15.
A theoretical approach based on density functional theory (DFT) was developed to determine the electronic Huynh parameter for bidentate ligands (HEP2). The C chemical shift of the carbene carbon atom in the 1,3-diisopropylbenzimidazolin-2-ylidene ligand (Pr-bimy) was calculated within the model complexes [PdBr(L)(Pr-bimy)], where L represents a bidentate ligand. Strong correlations were observed between the calculated and experimental chemical shifts for both -donor and -donor L ligands, with values of 0.9699 and 0.9926, respectively. This DFT approach demonstrates the potential for estimating the HEP2 parameter of bidentate ligands of these types. This method was applied to estimate the HEP2 values for three bis(-heterocyclic carbene) ligands containing carboxylate groups, (diNHC), which are explored as ligands in this study. These NHC ligands were derived from three precursor compounds: 1-(carboxymethyl)-3-((3-(carboxymethyl)-1-imidazol-3-ium-1-yl)methyl)-1-imidazol-3-ium bromide (), 1-(1-carboxyethyl)-3-((3-(1-carboxyethyl)-1-imidazol-3-ium-1-yl) methyl)-1-imidazol-3-ium bromide (), and 2-(1-(2-(1-(carboxymethyl)-1-imidazol-3-ium-3-yl)ethyl)-1-imidazol-3-ium-3-yl)acetate bromide (). They were synthesized and characterized using IR, NMR, and single-crystal X-ray crystallography (for and ). The interaction of and with AgO in the presence of aqueous sodium hydroxide produced the complexes [Na(HO)][Ag(diNHC)] () and [Na(HO)][Ag(diNHC)] (), respectively. Complex was structurally characterized, revealing a binuclear structure in which the bis-carbene ligand adopts a bridging μ-κ(C),κ(C') coordination. Furthermore, exhibited reactivity in transmetalation, allowing the synthesis of complex [Na(HO)][Pd(diNHC)] () through a reaction with palladium acetate. Complex , which was also structurally characterized, consists of a mononuclear tetracarbene species where each bis-carbene ligand coordinates in a bidentate κ(C,C') fashion.
开发了一种基于密度泛函理论（DFT）的理论方法来确定双齿配体的电子Huynh参数（HEP2）。在模型配合物[PdBr(L)(Pr-bimy)]中计算了1,3-二异丙基苯并咪唑啉-2-亚基配体（Pr-bimy）中卡宾碳原子的C化学位移，其中L代表双齿配体。对于σ-供体和π-供体L配体，计算得到的化学位移与实验化学位移之间均观察到强相关性，其相关系数分别为0.9699和0.9926。这种DFT方法证明了估算这类双齿配体HEP2参数的潜力。该方法被用于估算三种含羧基的双（N-杂环卡宾）配体（diNHC）的HEP2值，本研究将其作为配体进行探索。这些NHC配体衍生自三种前体化合物：1-（羧甲基）-3-（（3-（羧甲基）-1-咪唑-3-鎓-1-基）甲基）-1-咪唑-3-鎓溴化物（）、1-（1-羧乙基）-3-（（3-（1-羧乙基）-1-咪唑-3-鎓-1-基）甲基）-1-咪唑-3-鎓溴化物（）和2-（1-（2-（1-（羧甲基）-1-咪唑-3-鎓-3-基）乙基）-1-咪唑-3-鎓-3-基）乙酸溴化物（）。使用红外光谱、核磁共振光谱和单晶X射线晶体学（用于 和 ）对它们进行了合成和表征。在氢氧化钠水溶液存在下， 和 与AgO反应分别生成配合物[Na(HO)][Ag(diNHC)]（）和[Na(HO)][Ag(diNHC)]（）。对配合物 进行了结构表征，揭示了一种双核结构，其中双卡宾配体采用桥连μ-κ(C),κ(C')配位。此外， 在金属转移反应中表现出反应活性，通过与乙酸钯反应可合成配合物[Na(HO)][Pd(diNHC)]（）。配合物 也进行了结构表征，它由单核四卡宾物种组成，其中每个双卡宾配体以双齿κ(C,C')方式配位。
