Strukturen der Alkalimetallsalze aromatischer, heterocyclischer Amide: Synthese und Struktur von Kronenether‐Addukten der Alkalimetall‐Pyrrolide

Abstract

AbstractStructures of Alkali Metal Salts of Aromatic, Heterocyclic Amides: Synthesis und Structure of Crown Ether Adducts of the Alkali Metal PyrrolidesThe synthesis of eight alkali metal pyrrolide crown ether complexes is reported: Lithium‐pyrrolide(12‐crown‐4) (1), sodium‐pyrrolide(15‐crown‐5) (2), potassium‐pyrrolide(18‐crown‐6) (3), rubidium‐pyrrolide(18‐crown‐6) (4), cesium‐pyrrolide(18‐crown‐6) (5), cesium‐pyrrolide(18‐crown‐6)(H2O)0.5 (6), rubidium‐pyrrolide(15‐crown‐5)2 (7), and rubidium‐hydrogendipyrrolide(15‐crown‐5)2 (8). The complexes 1 to 5 and 7 were synthesized from the alkali metal pyrrolide and the corresponding crown ether. Compound 6 was obtained from 5 and water, complex 8 from RbN(SiMe3)2, pyrrole, and 15‐crown‐5. The structures of 1, 2, 3, 4, 6, 7, and 8 could be determined by X‐ray diffraction. The complexes 1, 2, and 3 are mononuclear, the pyrrolide anion shows an η1(N)‐coordination to the metal cation. Complex 4 is also mononuclear, but with an unsymmetric η5‐side‐on‐coordination of the pyrrolide anion to the rubidium cation. In complex 6 two pyrrolide anions are bridged by a water molecule via hydrogen bonds and both pyrrolide anions are coordinated to cesium ions. Compounds 7 and 8 have a salt‐like structure with a sandwich‐like [Rb(15‐crown‐5)2]+ cation and an uncoordinated pyrrolide anion (7) or an uncoordinated hydrogen‐dipyrrolide anion (8).