ON SOME CHEMICAL PROPERTIES OF 1-PHENYLPHOSPHINDOLE

Abstract

The title compound 5 can be easily synthesized by combination of two published procedures. It undergoes quantitative lithium cleavage of the exocyclic P—Ph bond, and phosphorus substituent exchange by reaction with t-butyllithium. The phosphindolyl anion displays a ³¹P NMR signal at higher field than the corresponding phospholyl anion, and is also more reactive towards ethanol. This indicates a higher basicity and a lower aromaticity of the phosphindolyl anion vs. the phospholyl anion. Bromo derivatives in α-as well as β-position to phosphorus were also prepared. Reaction of 5 with Mn₂(CO)₁₀ afforded a π-phosphindolyl complex whereas reaction of t-butylphosphindole with Mn₂(CO)₁₀ only gave a [sgrave]-complex. Phosphindolyl anion with BrMn(CO)₅ gave μ-phosphido complexes but did not give any ferrocene analogue by reaction with FeCl₂, indicating a lowering of the stability of the phosphametallocenes upon benzoannelation.