Acid-Promoted Isomerization of a Tungsten−η1-2,5-Dihydropyrrolyl Complex to Its Tungsten−η1-2,3-Dihydropyrrolyl Isomer

Treatment of the tungsten−η 1 -2,5-dihydropyrrolyl complex 3 with a mixture of Ph 3 CBF 4 and water in cold CH 2 Cl 2 produced the tungsten−η 1 -2,3-dihydropyrrolium cation 7; this cation gradually lost one proton in CH 2 Cl 2 at 23 °C, to yield the tungsten−η 1 -2,3-dihydropyrrolyl species 5 .