Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056, Aachen, Germany.
CNRS, INSA, UPS, UMR 5215, LPCNO, Université de Toulouse, 135 avenue de Rangueil, 31077, Toulouse, France.
Chemistry. 2021 Feb 10;27(9):3002-3007. doi: 10.1002/chem.202004931. Epub 2021 Jan 18.
The fifteen-membered NNNNN macrocycle Me PACP (Me PACP=1,4,7,10,13-pentamethyl-1,4,7,10,13-pentaazacyclopentadecane) stabilized the [CaH] fragment as a dimer with a distorted pentagonal bipyramidal coordination geometry at calcium. The hydride complex was prepared by protonolysis of calcium dibenzyl with the conjugate acid of Me PACP followed by hydrogenolysis or treating with OctSiH of the intermediate calcium benzyl cation. The calcium hydride catalyzed the hydrogenation and hydrosilylation of unactivated olefins faster than the analogous calcium complex stabilized by the twelve-membered NNNN macrocycle Me TACD (Me TACD=1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane). Kinetic investigations indicate that higher catalytic efficiency for the Me PACP stabilized calcium hydride is due to easier dissociation of the dimer in solution when compared to the Me TACD analogue.
十五元氮杂大环 MePACP（MePACP=1,4,7,10,13-五甲基-1,4,7,10,13-五氮杂环十五烷）将[CaH]片段稳定为二聚体，其中钙原子具有扭曲的五重双锥配位几何形状。该氢化物络合物是通过 MePACP 的共轭酸质子解二苄基钙，然后进行氢解或用中间体钙苄基阳离子的 OctSiH 处理来制备的。钙氢化物比由十二元 NNNN 大环 MeTACD（MeTACD=1,4,7,10-四甲基-1,4,7,10-四氮杂环十二烷）稳定的类似钙络合物更能快速催化未活化烯烃的加氢和硅氢化反应。动力学研究表明，MePACP 稳定的钙氢化物具有更高的催化效率，这是由于与 MeTACD 类似物相比，在溶液中二聚体更容易解离。
