From 2-Phosphino-2H-Phosphirene to 1-Phosphino-1H-Phosphirene,1#lambda#~5,2#lambda#~3-Diphosphete,and 1,2-Dihydro-1#lambda#~3,2#lambda#~3-Diphosphete:an Experimental and Theoretical Study

摘要

The [bis(diisopropylamino)phosphino](trimethylsilyl)carbene 4 reacts cleanly with etrt-butylphosphallkyne 2 to give 2-phosphion-2H-phosphirene 5, which was spectroscopically characterized. Heterocycle 5 is thermally unstable and quantitatively rearranges after 3 h at room temperature into the 1#lambda#~5,2#lambda#~3-diphosphete 3. Irradiation of 5 at room temperature (#lambda#=254nm)with a Rayonnet phosochemical reactor produces 1-phosphino-1H-phosphirene (10%),1,2-dihydrodiphosphete 7 (3%),and diphosphete 3(87%). Irradiation of 3 with a high pressure mercury lamp at #lambda#=254nm affords the dihydrodiphosphete 7,which was isolated in 69% yield. Calculations carried out on heterocycles 3 and 5-7 emphasize the crucial effect the amino substituents have on the stability of #lambda#~5-phosphacyclobutadiene derivatives, and show that the intrinsic difference in the thermodynamic stability between 1H and 2H-phosphirenes is rather small (68 kJmol~(-1)).