Achiral and Chiral PNP-Pincer Ligands with a Carbazole Backbone: Coordination Chemistry with d8 Transition Metals
Achiral and Chiral PNP-Pincer Ligands with a Carbazole Backbone: Coordination Chemistry with d8 Transition Metals
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DOI：
10.1021/ic302454n
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发表时间：
2013-02-18
影响因子：
4.6
通讯作者：
Gade, Lutz H.
中科院分区：
文献类型：
--
作者：
Grueger, Nora;Rodriguez, Lara-Isabel;Gade, Lutz H.
合成了两种新的单阴离子PNP钳型配体，即非手性3,6-二叔丁基-1,8-双((二苯基膦)甲基)-9H-咔唑CbzdiphosH (5)和手性3,6-二叔丁基-1,8-双(((2R,5R)-2,5-二苯基膦-1-基)甲基)-9H-咔唑CbzdipholH (7)，两者最初都是以其硼烷配合物形式制备的。 CbzdiphosH 的合成基于关键中间体 1,8-双(溴甲基)-3,6-二叔丁基-9H-咔唑 (3) 与二苯基磷化锂-硼烷络合物之间的反应。手性配体CbzdipholH通过用锂(2R,5R)-2,5-二苯基磷杂环硼烷络合物处理3并随后用二乙胺脱保护来制备。研究了两种配体与镍、钯和铑的络合作用，发现配体的构象行为不同。尽管所有晶体学表征的配合物中供体原子的排列近似为正方形平面，但 Cbzdiphos 配合物中的咔唑平面相对于配位面倾斜。另一方面，在 Cbzdiphol 配合物中观察到螺旋扭曲。
Two new monoanionic PNP pincer type ligands have been synthesized, the achiral 3,6-di-tert-butyl-1,8-bis((diphenyl-phosphino)methyl)-9H-carbazole CbzdiphosH (5) and the chiral 3,6-di-tert-butyl-1,8-bis(((2R,5R)-2,5-diphenylphospholan-1-yl)methyl)-9H-carbazole CbzdipholH (7), both of which were initially prepared as their borane complexes. The synthesis of CbzdiphosH is based on the reaction between the key intermediate 1,8-bis(bromomethyl)-3,6-di-tert-butyl-9H-carbazole (3) and lithium diphenylphosphide-borane complex. The chiral ligand CbzdipholH was prepared by treating 3 with lithium (2R,5R)-2,5-diphenylphospholanide-borane complex and subsequent deprotection with diethylamine. The complexation of the two ligands with nickel, palladium and rhodium was investigated, for which the conformational behavior of the ligands was found to be different. Although the arrangement of the donor atoms in all crystallographically characterized complexes is approximately square planar, the carbazole plane in Cbzdiphos complexes is inclined relative to the coordination plane. On the other hand, a helical twist is observed in Cbzdiphol complexes.