Lewis Superacidic Heavy Pnictaalkene Cations: Comparative Assessment of Carbodicarbene-Stibenium and Carbodicarbene-Bismuthenium Ions
Lewis Superacidic Heavy Pnictaalkene Cations: Comparative Assessment of Carbodicarbene-Stibenium and Carbodicarbene-Bismuthenium Ions
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刘易斯超酸性重五烯阳离子：碳二碳烯-锑和碳二碳烯-铋离子的比较评估
DOI：
10.1021/acs.inorgchem.2c03135
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发表时间：
2022
影响因子：
4.6
通讯作者：
Gilliard, Robert J.
中科院分区：
文献类型：
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作者：
Warring, Levi S.;Walley, Jacob E.;Dickie, Diane A.;Tiznado, William;Pan, Sudip;Gilliard, Robert J.
我们报告了使用Gutmann-Beckett （GB）方法对一系列碳-锑和-铋离子的刘易斯酸度的综合评估。以（CDC） pnbr3和[(pyCDC)PnBr2][Br] （CDC = carbodicarbene; Pn = Sb或Bi； py = pyridyl）为原料，用卤化物抽象合成了这些新的锑和铋阳离子。（CDC）SbBr3(1)与一种或两种等量的AgNTf2（NTf2=双（三氟甲烷磺酰）亚胺）或agsbf6反应得到双炔单链和指示式[(CDC)SbBr3 - n][A]n（2 - 4;n= 1,2; A = NTf2或SbF6）。此外，还分离出了三萜烯[(CDC)2Sb][NTf2]3(5)，这些分子共同填补了阳离子烯系列之间的空白。将Sb阳离子与相关的cdc -双烯配合物进行了比较6 - 9。为了制备高路易斯酸化合物，我们采用了一种三齿双（吡啶）碳二苯（pyCDC）作为配体来获得[(pyCDC)PnBr2][Br]（10,12）和三齿[(pyCDC)Pn][NTf2]3(Pn = Sb (11), Bi(13))，而不需要像合成5那样使用第二种CDC。结合化学价理论的自然轨道，通过电子密度和能量分解分析，阐明了这些配合物的成键情况。每个配合物中都存在一个cd - pn双键相互作用，由一个较强的σ键和一个较弱的π键组成，π键随着配合物中阳离子电荷的增加而逐渐增强。值得注意的是，[(CDC)SbBr][NTf2]2(4)的受体数（an）（84）与典型的Lewis酸（如BF3）相当，而三位化pnicta烯烃络合物11和13表现出强烈的Lewis酸，ANs分别为109 （Pn = Sb）和84 (Pn = Bi)，这是在任何锑或铋阳离子中报道的最高值。此外，计算得到的11和13的氟离子亲和值分别为99.8和94.3 kcal/mol，均大于SbF5的85.1 kcal/mol，表明它们是Lewis超强酸。
We report a comprehensive assessment of Lewis acidity for a series of carbone-stibenium and -bismuthenium ions using the Gutmann–Beckett (GB) method. These new antimony and bismuth cations have been synthesized by halide abstractions from (CDC)PnBr3and [(pyCDC)PnBr2][Br] (CDC = carbodicarbene; Pn = Sb or Bi; py = pyridyl). The reaction of (CDC)SbBr3(1) with one or two equivalents of AgNTf2(NTf2= bis(trifluoromethanesulfonyl)imide) or AgSbF6gives stibaalkene mono- and dications of the form [(CDC)SbBr3–n][A]n(2–4;n= 1,2; A = NTf2or SbF6). The stibaalkene trication [(CDC)2Sb][NTf2]3(5) was also isolated and collectively these molecules fill the gap among the series of cationic pnictaalkenes. The Sb cations are compared to the related CDC-bismaalkene complexes6–9. With the goal of preparing highly Lewis acidic compounds, a tridentate bis(pyridine)carbodicarbene (pyCDC) was used as a ligand to access [(pyCDC)PnBr2][Br] (10,12) and trications [(pyCDC)Pn][NTf2]3(Pn = Sb (11), Bi (13)), forgoing the need for a second CDC as used in the synthesis of5. The bonding situation in these complexes is elucidated through electron density and energy decomposition analyses in combination with natural orbital for chemical valence theory. In each complex, there exists a CDC–Pn double bonding interaction, consisting of a strong σ-bond and a weaker π-bond, whereby the π-bond gradually strengthens with the increase in cationic charge in the complex. Notably, [(CDC)SbBr][NTf2]2(4) has an acceptor number (AN) (84) that is comparable to quintessential Lewis acids such as BF3, and tricationic pnictaalkene complexes11and13exhibit strong Lewis acidity with ANs of 109 (Pn = Sb) and 84 (Pn = Bi), respectively, which are among the highest values reported for any antimony or bismuth cation. Moreover, the calculated fluoride ion affinities (FIAs) for11and13are 99.8 and 94.3 kcal/mol, respectively, which are larger than that of SbF5(85.1 kcal/mol), which suggest that these cations are Lewis superacids.