Methyldiphenylphosphine Oxide and Dimethylphenylphosphine Oxide

Frustrated and Realized Hydrogen Bonding in 4-Hydroxy-3,5-ditertbutylphenylphosphine Derivatives

“…All synthesized compounds (Scheme 1) were fully characterized by melting point and 1D and 2D NMR spectroscopy. 1 H, 31 P, 13 C, 1 H− 1 H gCOSY, 1 H− 13 C gHSQC, and 1 H− 13 C gHMBC NMR spectra are in full agreement with the structures shown (see Experimental Section and the Supporting Information for full details). Synthesis of the reagent 2,6-ditertbutyl-4-bromophenoxy-trimethylsilane, used as a precursor in the synthesis of phosphines 1 and 3, was recently optimized, and its crystal structure was reported.…”

“…16 Phosphine chalcogenides were obtained using standard methods. 31,32 The phosphine oxides 2c and 4c were synthesized by refluxing the phosphines with H 2 O 2 in acetone. Phosphine sulfides 2a, 3a, and 4a and selenides 2b, 3b, and 4b were obtained by heating the phosphines with the corresponding chalcogens in xylenes in order to overcome the low solubility of S and Se in organic solvents.…”

“…Higher frequency (shielding) is observed for the siloxanes 1 and 3 compared to phenols 2 and 4; similarly, the tris-(3,5-ditertbutylphenyl)phosphines 3 and 4 are more shielded than the diphenyl phosphines 1 and 2. Upon oxidation, the 31 Calculations on geometry-optimized structures at the B3LYP-D3BJ/6-31+G(2d,p) level of theory using Grimme's damped empirical dispersion correction, with frequency calculations to confirm true minima. b Geometries are taken from the DFT calculations to avoid complications with different conformations in crystal structures; the lowest-energy conformations were employed when more than one structure could be minimized.…”

“…1 H NMR (700.44 MHz, CDCl 3 ): δ H 7 0.39 (s, 27H, 9 CH 3 ); H 6 1.29 (s, 54H, 27 CH 3 ); H 2 7.09 (d, 6H, J H−P = 8.4 Hz) 31. P{1 H} NMR (121.49 MHz, CDCl 3 ): δ −9.15, in good agreement with the literature values 16.…”