Der thermische Zerfall des tBu2P?PP(Me)tBu2

The Thermal Decomposition of ^tBu₂P? P?P(Me)^tBu₂ The thermal decomposition of ^tBu₂P? P?P(Me)^tBu₂ 2 in C₆H₆ at 20°C is detectable after 10 h; ^tBu₂PMe, (^tBu₂P)₂PH and small amounts of the cyclotetraphosphanes P₄(P^tBu₂)₄ and P₄(P^tBu₂)₂ are formed. At 70°C (14 h) 83% of 2 are decomposed, and even 96% after 74 h. The main products are ^tBu₂PMe (68%) and P₄(P^tBu₂)₄ (20%). With 2,3-dimethyl-1,3-butadiene as a trapping reagent ^tBu₂PMe (62%) is still the main product, however, P₄(P^tBu₂)₄ is no longer found, but 1,2-bis(di-tert-butylphosphino)-4,5-dimethyl-1,2-diphosphacyclohexene-4 (22%) is formed instead. Also with cyclohexene ^tBu₂PMe (78%) remains the major product besides P₄(P^tBu₂)₄ (9%) and small amounts of the trapping product 7-di-tert-butylphosphino-7-phosphabicyclo4.1.0]heptane. Thus, the thermal decomposition of 2 at 70°C proceeds very similar to that of ^tBu₂P? P?P(Br)^tBu₂ at ?30°C and starts yielding and the phosphinophosphinidene ^tBu₂P? P. In CH₂Cl₂ the decomposition of 2 includes the chlorination of the ylidic molecule.