Crystal structure of a supramolecular lithium complex of p-tert-butylcalix[4]arene

Abstract

Crystals of a supramolecular lithium complex with a calix[4]arene derivative, namely tetramethanollithium 5,11,17,23-tetra-tert-butyl-25,26,27-trihydroxy-28-oxidocalix[4]arene methanol monosolvate, [Li(CH3OH)4](C44H55O4)·CH3OH or [Li(CH3OH)4]+·(calix[4]arene−)]·CH3OH (where calix[4]arene− represents a mono-anion species because of deprotonation of one H atom of the calixarene hydroxy groups), were obtained from p-tert-butylcalix[4]arene reacted with LiH in tetrahydrofuran, followed by recrystallization from methanol. The asymmetric unit comprises one mono-anionic calixarene molecule, one Li+ cation coordinated to four methanol molecules, and one methanol molecule included in the calixarene cavity. The calixarene molecule maintains a cone conformation by intramolecular hydrogen bonding between one phenoxide (–O−) and three pendent calixarene hydroxy groups (–OH). The coordinated methanol molecules around the metal cation play a significant role in forming the supramolecular assembly. The crystal structure of this assembly is stabilized by three sets of intermolecular interactions: (i) hydrogen bonds involving the –OH and –O− moieties of the calixarene molecules, the –OH groups of the coordinated methanol molecules, and the –OH group of the methanol molecule included in the calixarene cavity; (ii) C—H...π interactions between the calixarene molecules and/or the coordinated methanol molecules; (iii) O—H...π interactions between the calixarene molecule and the included methanol molecule.