ORGN 520 |
| Structure of 4-phenyl-4-seleno-1,4-thiaphosphinane (1), 1,1-dimethyl-4-phenyl-4-seleno-1,4-silaphosphinane (2), and 1,1-dimethyl-4-phenyl-1,4-silaphosphinane (3) was studied by the methods of dipole moments (DM), Kerr effect, molecular mechanics (MM), and theoretical calculations (DFT B3LYP/6-31G*). Analysis of experimental and calculated (vector-additive scheme) DM led to a conclusion about the preference of chair conformer with equatorial phenyl substituent for (1-3). Chair conformation with parallel arrangement of the phenyl ring and the P=Se group is preferred for (2) according to experimental and calculated Kerr constants. The conformers with axial P=Se bond (1, 2) or the lone pair at the P atom (3) have the energy minima (ΔE = 0 kcal.mol-1) according to MM and B3LYP/6-31G* calculations. Theoretical results correspond to experimental data and calculated DM. Chair conformation with equatorial exocyclic phenyl substituent is preferred for 1,4-heterophosphinanes independently of the nature of second heteroatom in phosphorus heterocycle (sulfur or silicon), and the coordination state of the phosphorus atom (PIII or PIV). |
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Physical Organic Chemistry, Metal-Mediated Reactions, Asymmetric Reactions and Syntheses
8:00 PM-10:00 PM, Tuesday, August 21, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Organic Chemistry |