Synthesis and molecular and supramolecular structures of a series of triarylphosphines P(Ph) 3−n {4-RO-3,5-( t Bu) 2 -C 6 H 2 } n (n = 1, 3; R = SiMe 3 , H) are reported. Chemical oxidation products E=P(Ph) 3−n {4-RO-3,5-( t Bu) 2 -C 6 H 2 } n (E = O, S, and Se; n = 1, 3; R = SiMe 3 , H) are also reported. Crystal structures of the reported compounds were determined by single-crystal X-ray diffraction, using a Hirshfeld atom refinement with NoSpherA2 through OLEX2, which provides an average improvement in C−C bond distance precision of 35%. Phosphine basicity for the phosphines with n = 1, R = H and n = 3, R = SiMe 3 , H was determined using the 1 J P,Se values of the respective selenides; 1 J P,Se = 699 Hz for E = Se, n = 3, and X = H identifies the most basic triarylphosphine ever reported. Intermolecular interactions allow classification of the 17 structures into 4 categories: those with only dispersion-induced short contacts, those with frustration of H-bonding, those with only classic H-bonding, and those with combinations of classic and frustration of H-bonding. A "double phenol embrace" classified by an R 2 2 (4) graph set is a weak intermolecular synthon organizing lattices with 2,6-ditertbutylphenol functional groups. Classic H-bonding occurs only when E = O.

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The crystal structures of 5-bromo-1,3-di-tert-butyl-2-[(trimethylsilyl)oxy]benzene, C17H29BrOSi, (I), 1,3-di-tert-butyl-2-[(trimethylsilyl)oxy]benzene, C17H30OSi, (II), and N-(2,6-diisopropylphenyl)-1,1,1-trimethyl-N-(trimethylsilyl)silanamine, C18H35NSi2, (III), are reported. Compound (I) crystallizes in space group P21/c with Z′ = 1, (II) in Pnma with Z′ = 0.5 and (III) in Cmcm with Z′ = 0.25. Consequently, the molecules of (II) are constrained by m and those of (III) by m2m site symmetries. Despite this, both (I) and (II) are distorted towards mild boat conformations, as is typical of 2,6-di-tert-butyl-substituted phenyl compounds, reflecting the high local steric pressure of the flanking alkyl groups. Compound (III) by contrast is planar and symmetric, and this lack of distortion is compatible with the lower steric pressure of the flanking 2,6-diisopropyl substituents.

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