Vibrational spectra, conformational properties and argon-matrix photochemistry of diacetyl diselenide, CH3C(O)Se2C(O)CH3

JOVANNY A. GÓMEZ CASTAÑO; ROSANA M. ROMANO; ANA R. SALAMANCA; GERMÁN AMÉSQUITA; HELMUT BECKERS; HELGE WILLNER; C. O. DELLA VÉDOVA

Carlos Paz

Conferencia; 13th Latin American Conference on Physical Organic Chemistry; 2015

By oxidation of selenoacetic acid, CH3C(O)SeH, we have prepared for the first time diacetyl diselenide, [CH3C(O)Se]2. Analysis of FTIR and Raman spectra of its net liquid and FTIR spectrum of the molecule isolated in argon matrix at low temperatures reveals a conformational equilibrium between two structures, which agree nicely with the two more stable rotamers predicted by our three−dimensional potential energy surface (PES) scan, optimization and frequency computational calculations using B3LYP or MP2 theoretical levels in combination with 6-31+G(d), 6-311++G(3df,3dp) or aug-cc-pvDZ basis sets. Energetic properties of three minima found theoretically were further studied in terms of donor−acceptor interactions by Natural Orbital Bonding (NBO) calculations at the same levels of theory, from which was possible to rationalize the conformational stability order and molecular structures by means of vicinal hyperconjugative delocalizations involving lone pairs on selenium or oxygen atoms and C=O, C−C or Se−C antibonding orbitals. The photochemistry of compound in argon matrix in the range between 200 and 800 nm was also investigated, thus revealing apparently only one photochemical path to produce ketene, CH2CO, methylselane, CH3SeH, and carbonyl selenide, OCSe.