Bicyclic phosphanes. Part 2. Spontaneous dimerization of a constrained bicyclic phosphane. The crystal and molecular structure of a tricyclic compound containing the dioxadiazadiphosphecine ring

Abstract

The dimerization of 3,3,7,7-tetramethyl-2,8-dioxa-5-aza-1-phospha^IIIbicyclo[3.3.0]octane (1) leads to octahydro-2,2,6,6,10,10,14,14-octamethylbis-1,2,3-oxazaphospholo[2,3-b:2′,3′-g]-1,6,3,8,2,7-dioxadiazadiphosphecine (2), a tricyclic compound with sixteen atoms around the periphery. The preparation, identification, and the X-ray structure are described. A pathway for the formation of the dimer is suggested by the trans-position of the two phosphorus Ione pairs.