Structural diversity in a series of alkyl-substituted cesium aryloxides.

A family of cesium aryloxides Cs(OAr) were synthesized and structurally characterized from the reaction of 1:1 or 1:excess stoichiometry of Cs(0) 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) (1), Cs(5)(oPP)(5) (2), Cs(4)(oBP)(4)(H-oBP)(6) (3x, shown), Cs(3)(DMP)(3) (4), Cs(2)(DIP)(2) (5), Cs(DIP)(H-DIP) (5x), and Cs(DPhP) (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 (133)Cs NMR spectroscopy, and for each compound, a single (133)Cs 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.