Reaction of a cyclic triphosphenium ion with triflic acid and SnX2 (X = Br or Cl):: A 31P NMR study

The di-ium dication formed by triflic acid protonation of the cyclic triphosphenium ion derived from 1,4-bis-diphenylphosphinobutane, (dppb), and PX3(X = Br or Cl) decomposes via an acyclic dication bearing a -PHX group; this intermediate is reduced by SnX2 in the presence of HX to yield a dication with a -PH2 primary phosphane terminal group, which is comparatively stable. The structure of this species has been unequivocally confirmed by (31)p solution-state NMR spectroscopy. (c) 2007 Wiley Periodicals, Inc.