Munshi Sandip, Gupta Geetika, Gourlaouen Christophe, Dagorne Samuel, Wehmschulte Rudolf J
Institute of Chemistry, Université de Strasbourg, CNRS, Strasbourg, 67000, France.
Laboratoire de Modélisation et Simulations Moléculaires, Université de Strasbourg, CNRS, Strasbourg, 67000, France.
Chemistry. 2025 Jul 22;31(41):e202501763. doi: 10.1002/chem.202501763. Epub 2025 Jul 7.
The syntheses of calcium carborates, Ca[HexCBCl], 1, Ca[HCBCl], 2, and Ca[MeCBCl]·2(o-DFB), 3·2(o-DFB), (o-DFB = 1,2-difluorobenzene) including the structure of 2·4(o-DFB) are described. The large size of the Ca cation is reflected by the coordination geometry with the Ca center being coordinated by three Cl donors from each of the carborate anions and one F donor from each of the two coordinated solvent molecules. Based on B NMR and DOSY NMR studies, the salts 1, 2 and 2·2(o-DFB) form close ion pairs in PhBr and o-DFB solutions. The Fluoride Ion Affinities (FIA) in PhBr for the salts 1 and 2·2(o-DFB) were DFT-calculated (ωB97XD/6-31 + G**) at 211.3 kJ mol and 217.5 kJ mol, respectively, which is below that of the landmark Lewis acid B(CF) (241.5 kJ mol). The Ca center in salt 1 is sufficiently Lewis acidic to coordinate 1,5-cyclooctadiene (1,5-COD) and 2,6-octadiyne and to catalyze the hydrosilylation of 1-hexene and several alkynes, albeit slowly. Compound 1 also displays moderate activity as a catalyst for transfer hydrogenation catalysis and carbonyl-olefin metathesis (COM), a first for Ca compounds.
描述了碳酸钙Ca[HexCBCl]（1）、Ca[HCBCl]（2）和Ca[MeCBCl]·2(o-DFB)（3·2(o-DFB)，其中o-DFB = 1,2-二氟苯）的合成，包括2·4(o-DFB)的结构。Ca阳离子的大尺寸通过配位几何结构体现，Ca中心由每个硼酸根阴离子的三个Cl供体和两个配位溶剂分子中的每个的一个F供体配位。基于B NMR和DOSY NMR研究，盐1、2和2·2(o-DFB)在PhBr和o-DFB溶液中形成紧密离子对。通过DFT计算（ωB97XD/6-31 + G**）得出盐1和2·2(o-DFB)在PhBr中的氟离子亲和力（FIA）分别为211.3 kJ/mol和217.5 kJ/mol，低于标志性路易斯酸B(CF)（241.5 kJ/mol）。盐1中的Ca中心具有足够的路易斯酸性，能够与1,5-环辛二烯（1,5-COD）和2,6-辛二炔配位，并催化1-己烯和几种炔烃的硅氢化反应，尽管反应缓慢。化合物1作为转移氢化催化和羰基-烯烃复分解反应（COM）的催化剂也表现出适度的活性，这对Ca化合物来说尚属首次。
