Molecular structures and conformations of phenylglyoxal and 1-phenyl-1,2-propanedione as determined by gas-phase electron diffraction

The molecular structures of phenylglyoxal and 1-phenyl-1,2-propanedione have been studied by gas-phase electron diffraction at nozzle temperatures of 74 and 73 o C, respectively. For both molecules the data are consistent with nonplanar models with the torsional angle O(O=C-C=O) of about 130 o . The phenyl rings are nearly coplanar with the carbonyl group (O ph =11(9) o and 8(11) o , respectively)