121955-71-3Relevant academic research and scientific papers
THE THIRD ROW ANOMERIC EFFECT. CONFORMATIONAL ANALYSIS OF 2-PHENYLTHIO- AND 2-PHENYLSELENO-1,3-DISELENANES.
Pinto, B. Mario,Johnston, Blair D.,Nagelkerke, Ruby
, p. 389 - 403 (2007/10/02)
The conformational behavior of cis- and trans-5-methyl-2-phenylthio- and -2-phenylseleno-1,3-diselenanes has been examined by means of 13C nmr and 77Se nmr spectroscopy.Whereas the cis isomers exhibit highly biased equilibria, the trans isomers display readily measurable equilibria at the slow-exchange limit.Direct integration of the individual conformer resonances in the low temperature spectra of the latter isomers yields ΔG147K values of -0.33+/-0.01 (SPh) and -0.08+/-0.01 (SePh) kcal mol-1 in favor of the diaxial conformer.The conformational free energy of the methyl group in 5-methyl-1,3-diselenane (ΔG147K = +0.87+/-0.03 kcal mol-1) is then used to derive ΔG147K values of -1.20+/-0.04 and -0.96+/-0.04 kcal mol-1 for the equilibrium in 2-phenylthio- and 2-phenylseleno-1,3-diselenane, respectively.Since the conformational free energy, ΔG147K' of the 2-methyl group in 2-methyl-1,3-diselenane is +1.04+/-0.01 kcal mol-1, it is argued that there exists a significant Se-C-S and Se-C-Se anomeric effect.
