Reduction of phosphorus substituted bulky amidines

Abstract

1 online resource (viii, 57 pages) : illustrations, charts, graphsIncludes abstract and appendix.Includes bibliographical references (pages 40-45).A series of bulky N,N&rsquo; disubstituted amidines with bulky 2,6-diisopropyl substituents and theircorresponding PCl2 substituted derivatives were synthesized. PCl2 substituted formamidine, methyl amidine, and p-methylphenyl amidine derivatives were successfully synthesized, and characterized by 1H, 13C, and 31P NMR spectroscopy, along with X-ray crystallography. The P-N bonds were determined to be longer than previously described N-bound PCl2 substituted compounds. Furthermore, crystallographic data shows a planar geometry about the N-C-N-P linkage, proving conjugation within these compounds. Reducing agents, Mg, Cp2Co, and sodium napthalenide were then employed to the PCl2 substituted amidines. Notably, reduction of the PCl2&nbsp;substituted p-methylphenyl amidine resulted in the selective formation of the corresponding diphosphene which was characterized by 1H, 13C, and 31P NMR spectroscopy, along with X-ray crystallography. Crystallographic data resulted in P-P bond lengths equivalent to previously reported N-bound diphosphenes. Furthermore, the P-P-N-C-N linkage for one side of the diphosphene existed in a cis-planar fashion, which is a new geometry observed for diphosphenes. This result prompted the idea to react the diphosphene with an oxonium acid which is believed to form a 5-membered heterocyclic cation that was characterized by 31P NMR.</p