Structural Diversity in a Series of Alkyl-Substituted Cesium Aryloxides

A family of cesium aryloxides [Cs(OAr)]n were synthesized and structurally characterized from the reaction of 1:1 or 1:excess stoichiometry of Cs0 and the appropriate alkyl-substituted phenol: 2-alkylphenol [alkyl = methyl (H-oMP), isopropyl (H-oPP), and tert-butyl (H-oBP)] and 2,6-dialkylphenol [alkyl = methyl (H-DMP), isopropyl (H-DIP), tert-butyl (H-DBP), and phenyl (H-DPhP)]. The products were structurally identified as [Cs(oMP)(H-oMP)2]n (1), [Cs5(oPP)5]n (2), [Cs4(oBP)4(H-oBP)6]n (3x, shown), [Cs3(DMP)3]n (4), [Cs2(DIP)2]n (5), [Cs(DIP)(H-DIP)]n (5x), and [Cs(DPhP)]n (7). Compounds 1–7 were found to adopt complex polymeric structures employing π interactions from the neighboring pendant phenoxide ligands. The solution behavior of these compounds was studied using solution 133Cs NMR spectroscopy, and for each compound, a single 133Cs NMR resonance was observed, with chemical shift values found to be strongly solvent-dependent. This implies that monomeric cesium salt species involving solvent interactions exist in solution.