Frustrated and realized hydrogen bonding in 4-hydroxy-3,5- ditertbutylphenylphosphine derivatives

Abstract

Synthesis and molecular and supramolecular structures of a series of triarylphosphines P(Ph)3–n{4-RO-3,5-(tBu)2-C6H2}n (n = 1, 3; R = SiMe3, H) are reported. Chemical oxidation products E=P(Ph)3–n{4-RO-3,5-(tBu)2-C6H2}n (E = O, S, and Se; n = 1, 3; R = SiMe3, 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 = SiMe3, H was determined using the 1JP,Se values of the respective selenides; 1JP,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 R22(4) graph set is a weak intermolecular synthon organizing lattices with 2,6-ditertbutylphenol functional groups. Classic H-bonding occurs only when E = O.