A Zwitterionic Tetrastanna(II) Cyclic Crown

Abstract

AbstractA 12‐membered zwitterionic tetrastanna(II) cycle 1 having a crown ether‐like topology has been isolated from the deprotonation of 1,1′‐methylenediimidazole (B) with two equivalents of Sn[N(SiMe3)2]2 (A). The solid‐state structure and NMR analysis confirms the tetrastanna(II) cycle 1 to be comprised of two stannate(II) and two stannyliumylidene ion pairs in alternating positions of the heterocycle. Computational analysis shows greater nucleophilicity at the proximally located stannate(II) centers. Nonetheless, the tetrastanna(II) cycle 1 remains poorly reactive due to engagement of SnII lone pair electrons in intramolecular donor‐acceptor interactions. Simple deprotonation reaction between Sn[N(SiMe3)2]2 (A) and N‐(diisopropylphenyl)imidazole (C) in equimolar ratio has led to a stannylene 2, involving the formation of a Sn−C covalent bond with the anionic imidazol‐2‐yl carbon center along with the release of NH(SiMe3)2. Compound 2 exists as a dimer, where the unsubstituted ring nitrogen atom coordinated intermolecularly to the other stannylene center.