text: This reagent was originally prepared by Conrad Willgerodt by reacting iodobenzene with a mixture of acetic acid and peracetic acid:
  PIDA can also be prepared from iodosobenzene and glacial acetic acid:
  More recent preparations direct from iodine, acetic acid, and benzene have been reported, using either sodium perborate or potassium peroxydisulfate as the oxidizing agent:
  The PIDA molecule is termed hypervalent as its iodine atom (technically a hypervalent iodine) is in its +III oxidation state and has more than typical number of covalent bonds.  It adopts a T-shaped molecular geometry, with the phenyl group occupying one of the three equatorial positions of a trigonal bipyramid (lone pairs occupy the other two) and the axial positions occupied by oxygen atoms from the acetate groups.  The "T" is distorted in that the phenyl-C to I to acetate-O bond angles are less than 90°.  A separate investigation of the crystal structure confirmed that it has orthorhombic crystals in space group Pnn2 and reported unit-cell dimensions in good agreement with the original paper.  The bond lengths around the iodine atom were 2.08 Å to the phenyl carbon atom and equal 2.156 Å bonds to the acetate oxygen atoms. This second crystal structure determination explained the distortion in the geometry by noting the presence of two weaker intramolecular iodine&ndash;oxygen interactions, resulting in an "overall geometry of each iodine [that] can be described as a pentagonal-planar arrangement of three strong and two weak secondary bonds."