title: Structural reinvestigation of ammonium hypophosphite: was dihydrogen bonding observed long ago?
abstract: The past decade has seen the explosive emergence of "dihydrogen bonds", interactions between the electrons of M-H sigma-bonds, where M is less electronegative than H (M = Al, B, Ga, Ir, Mo, Mn, Os, Re, Ru, W) and traditional proton donors. But 70 years ago, such an interaction was proposed by Zachariasen and Mooney [J. Chem. Phys. 1934, 2, 34-37] on the basis of their single-crystal X-ray diffraction structure (heavy atoms positions only) of ammonium hypophosphite (NH(4)H(2)PO(2)). We redetermined this structure at high resolution with a focus on the hydrogen atoms, using a modern diffractometer equipped with a CCD detector. Molecular orbital calculations were performed to investigate the charge density and the bond polarity of the P-H bonds and to assess their potential for participation in dihydrogen bonds. Neither the theory nor the X-ray structure supports the original claim of H...H interactions in this salt.
authors.affiliation: Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1322, USA.
authors.forename: Simona
authors.initials: S
authors.lastname: Marincean
authors.forename: Radu
authors.initials: R
authors.lastname: Custelcean
authors.forename: Robin S
authors.initials: RS
authors.lastname: Stein
authors.forename: James E
authors.initials: JE
authors.lastname: Jackson