Synthesis and structure of bis(para-methoxyphenyl)selenoxide and its monohydrate.: Theoretical considerations of the hydration of diorganoselenium oxides

The title compound was prepared by base hydrolysis of (p-MeOC6H4)(2)SeCl2 in water and isolated as the crystalline monohydrate, (p-MeOC6H4)(2)(SeOH2O)-H-., in which the water molecule is associated via hydrogen-bonding. Water-free (p-MeOC6H4)(2)SeO was obtained crystalline after drying and recrystallisation from toluene. Both crystal phases were investigated by single crystal X-ray diffraction. Preliminary DFT calculations at the B3LYP/LANL2DZdp level of theory suggest that the hydrogen bonded complexes (R2SeOH2O)-H-. (R = H, Me, Ph) are by 2.79, 3.36 and 11.10 kcal mol(-1) more stable than the corresponding elusive diorganoselenium dihydroxides R2Se(OH)(2). The hydrogen bond energies of (R2SeOH2O)-H-. (R = H, Me, Ph) are 5.98, 7.18 and 5.89 kcal mol(-1).