Crystal structure of a supra-molecular lithium complex of p-tert-butyl-calix[4]arene

Crystals of a supra-molecular lithium complex with a calix[4]arene derivative, namely tetra-methano-llithium 5,11,17,23-tetra-tert-butyl-25,26,27-trihy-droxy-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 hy-droxy groups), were obtained from p-tert-butyl-calix[4]arene reacted with LiH in tetra-hydro-furan, followed by recrystallization from methanol. The asymmetric unit comprises one mono-anionic calixarene mol-ecule, one Li⁺ cation coordinated to four methanol mol-ecules, and one methanol mol-ecule included in the calixarene cavity. The calixarene mol-ecule maintains a cone conformation by intra-molecular hydrogen bonding between one phenoxide (-O^-) and three pendent calixarene hy-droxy groups (-OH). The coordinated methanol mol-ecules around the metal cation play a significant role in forming the supra-molecular assembly. The crystal structure of this assembly is stabilized by three sets of inter-molecular inter-actions: (i) hydrogen bonds involving the -OH and -O^- moieties of the calixarene mol-ecules, the -OH groups of the coordinated methanol mol-ecules, and the -OH group of the methanol mol-ecule included in the calixarene cavity; (ii) C-H⋯π inter-actions between the calixarene mol-ecules and/or the coordinated methanol mol-ecules; (iii) O-H⋯π inter-actions between the calixarene mol-ecule and the included methanol mol-ecule.