From 2-Phosphino-2H-Phosphirene to 1-Phosphino-1H-Phosphirene, 1λ5,2λ3-Diphosphete, and 1,2-Dihydro-1λ3,2λ3-Diphosphete: an Experimental and Theoretical Study
作者:Muriel Sanchez、Régis Réau、Colin J. Marsden、Manfred Regitz、Guy Bertrand
DOI:10.1002/(sici)1521-3765(19990104)5:1<274::aid-chem274>3.0.co;2-p
日期:1999.1.4
The [bis(diisopropylamino)-phosphino](trimethylsilyl)carbene 4 reacts cleanly with tert-butylphosphaalkyne 2 to give 2-phosphino-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 = 254 nm) with a Rayonnet photochemical reactor produces 1-phosphino-1H-phosphirene 6 (10%), 1,2-dihydrodiphosphete 7 (3%), and diphosphete 3 (87%). Irradiation of 3 with a high pressure mercury lamp at lambda = 254 nm 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 kJ mol(-1)).