N-Oxoammonium salt


N-Oxoammonium salts are a class of organic compounds with the formula X−. The cation is of interest for the dehydrogenation of alcohols. Oxoammonium salts are diamagnetic, whereas the nitroxide has a doublet ground state. A prominent nitroxide is prepared by oxidation of oxyl, commonly referred to as +. A less expensive analogue is Bobbitt's salt.

Structure and bonding

Oxoammonium cations are isoelectronic with carbonyls and structurally related to aldoximes, and aminoxyl radicals, with which they can interconvert via a series of redox steps. According to X-ray crystallography, the N-O distance in BF4 is 1.184 Å, 0.1 Å shorter than the N-O distance of 1.284 Å in the charge-neutral TEMPO. Similarly, the N in + is nearly planar, but the O moves 0.1765 Å out of the plane in the neutral TEMPO.
The N-oxoammonium salts are used for oxidation of alcohols to carbonyl groups, as well as other forms of oxoammonium-catalyzed oxidations. The nitroxyl TEMPO reacts via its N-oxoammonium salt.