Hydrogen-Bonded Phosphorous Acids. Synthesis and Structure of Imidazolium-Containing Salts of Hydrogenphosphonate and Phenylphosphonate

Reaction of phosphorous acids with 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (1) and 1,3-dicyclohexyl-4,5-dimethylimidazol-2-ylidene (2) led to the formation of the hydrogen- bonded salts, [h(4,5-me)(ipr)2im]h2po3 (5) and [h(4,5-me)(cy)2im]phpo3h (6) (cy = cyclohexyl) in high yields. all were characterized by nmr, ir spectroscopy and single crystal x- ray diffraction. salts 5 and 6 crystallize in the monoclinic crystal system space groups. the x-ray structures of 5 and 6 reveal unsymmetrical and symmetrical dimers of the phosphoryl anion groups linked to each other via intermolecular o-h···o hydrogen bonds, respectively, and to the imidazolium cations through almost linear monofunctional c-h···o hydrogen bonds.