Diphenylmethane and diphenyl ether - experimental conformations and torsional surfaces calculated with AM1, MNDO, PM3, and density functional theory (Becke3LYP)

The complete energy surfaces of the torsion around the central C-O or C-CH2 bonds in diphenyl ether (DPE) and diphenylmethane (DPM) are calculated with semiempirical methods (AM1, MNDO, PM3) and density functional theory (Becke3LYP/3-21G). Stationary points are optimized at the Becke3LYP/6-31G(d) level of theory. The geometry of a very recently published X-ray structure of 4,4'-bis [N-(2,4,6-trimethyl)benzenesulfonamide] diphenylmethane (1), as well as the solid state structures of many other diphenyl ethers and diphenylmethanes, is found in the low-energy regions of the AM1 surfaces of the parent compounds.