Interactions in Molecular Crystals, 118. The Sodium(benzo‐15‐crown‐5) Salt of 2, 6‐Di(tert‐butyl)‐4‐methylphenol, a Sodium Phenolate with an Extremely Short Na+…O− Distance: Structure and Density Functional Calculations

Abstract

AbstractThe structure of crystals, isolated in low yield, from the attempted metallation of diphenylmethane in tetrahydrofuran solution containing benzo‐15‐crown‐5 at a sodium metal mirror is determined, surprisingly, to be the sodium (benzo‐15‐crown) salt of 2,6‐di(tert‐butyl)‐4‐methylphenol, an antioxidative stabilizer to prevent ether peroxide formation. The structure of the solvent‐shared contact ion pair (monoclinic P21/n, Z = 4, R1 = 0.06) proves a strong Na+…O− interaction at the extremely short distance of only 216 pm, a sixfold O‐coordination of the Na+ cation in a pentagonal pyramid, and a hemispherical distortion of the crown ether. Density functional calculations at the B3LYP/6‐31G* level, based on the structural data, reproduce, within a one‐dimensional hypersurface approach, the rather short Na+…O− distance, and predict Mulliken charges of +0.32 for Na′ and ‐0.71 for 0−, as well as a considerable polarization of the trialkyl phenolate anion.