Thermal [2 + 2] Cycloadditions between the Metallodiphosphene (η⁵-C₅Me₅)(CO)₂Fe−PP−Mes* and a Phosphaalkyne

Abstract

The synthesis of trans -1,2-dihydro-1-(2,4,6-tri- tert -butylphenyl)-2-(dicarbonyl-η 5 -pentamethylcyclopentadienylferrio)-4-diisopropylamino-1,2,3-triphosphete ( 9 ) was conducted by treating 1-(dicarbonyl-η 5 -pentamethylcyclopentadienylferrio)-2-(2,4,6-tri- tert -butylphenyl)diphosphene ( 7 ) with an equimolar amount of 2-diisopropylamino-1-phosphaethyne ( 2b ). Monitoring the reaction by 31 P{ 1 H} NMR evidenced the formation of trans -1,2-dihydro-1-(dicarbonyl-η 5 -pentamethylcyclopentadienylferrio)-2-(2,4,6-tri- tert -butylphenyl)-4-diisopropylamino-1,2,3-triphosphete ( 8 ) as an intermediate, which in solution slowly isomerized to the final product 9 .