Thermal ring-opening of [{2-bis(trimethylsilyl)methyl-3-1,2-azaphosphole complex 10c was obtained, together with the 7-aza-1-phosphanorbornadiene complex 16, the latter phenyl-2H-azaphosphirene-κP}pentacarbonyltungsten(0)] (8a) in the presence of dimethyl acetylenedicarboxylate through partial decomposition of 10c coupled with rearrangement and a DielsϪAlder reaction; the ratio 10c/16 (DMAD) led to the 2,3-bifunctionalized 1H-phosphirene complex 9a and the 4-phenyl-substituted 2H-1,2-was found to depend strongly on the molar ratio of complex 8b to DMAD. A cycloaddition reaction of the 2,3-azaphosphole complex 10a, the latter as a by-product. If a small amount of benzonitrile was added, complex 10a was bifunctionalized 1H-phosphirene complex 9a with 2,3dimethylbutadiene furnished the bicyclic phosphirane obtained as the main product, along with a small amount of the decomplexed 2H-1,2-azaphosphole 11, which could not complex 19, along with a small amount of the noncoordinated bicyclic phosphirane 20. Reaction of complex be isolated. Reaction of complex 10a with elemental sulfur furnished the corresponding P V sulfide 13. When the ring-9a with diethylamine yielded the phosphirane complex 21 as a 1,2-addition product, the diorganophosphane complex 22 opening of complex 8a was performed in the presence of two equivalents of DMAD and two equivalents of dimethyl through ring-opening of 9a, and the 3,4-functionalized 1,2dihydro-1-phosphet-2-one complex 23 through an cyanamide, we obtained the 4-dimethylamino-substituted 2H-1,2-azaphosphole complex 10b, together with the unprecedented ring-expansion reaction; the products 21, 22, 23 were formed in a ratio of ca. 1:1:1. The structures of the diastereomeric ∆ 3 -1,3,2-oxazaphospholene complexes 14a,b. On reaction of [{2-pentamethylcyclopentadienyl-3-phenyl-1H-phosphirene complex 9a, the 4-dimethylaminosubstituted 2H-1,2-azaphosphole complex 10b, the bicyclic 2H-azaphosphirene-κP}pentacarbonyltungsten(0)] (8b) and DMAD in toluene, the corresponding 1H-phosphirene phosphirane complex 19, the phosphirane complex 21, and the 1,2-dihydro-1-phosphet-2-one complex 23 have been complex 9b was only formed as a transient species and the P-coordinated P,C-cage compound 15 was the final product.
determined by single-crystal X-ray diffraction analysis. Using benzonitrile as solvent, the 4-phenyl-substituted 2Huble derivatives of P-heterocycles such as the 1-phospha-[ ] Part 15: Ref. [1] pholes such as 6, which is accessible by reaction of trimethyl [a]