CONTRIBUTIONS TO THE CHEMISTRY OF PHOSPHORUS .223. HEXAISOPROPYLICOSAPHOSPHANE(6), P20I-PR6 - PREPARATION AND STRUCTURE DETERMINATION OF 2 CONSTITUTIONAL ISOMERS BY NUCLEAR-MAGNETIC-RESONANCE

Hexaisopropylicosaphosphane(6) has been obtained by reaction of i-PrPCl2 with P4 and magnesium and subsequent thermolysis of the crude reaction product. The compound is formed as a mixture of two constitutional isomers 1 and 2 of equal abundance, which have been almost purely isolated by HPLC as a mixture of the diastereomers 1 a, 1 b and in the form of the separate configurational isomers 2a and 2b, respectively. According to NMR-spectroscopic investigations, the new conjuncto-phosphane skeletons of 1 and 2 consist of a P13(5)- and a P9(5)-structural element analogous to that of brexane and of two P11(5)-partial skeletons, respectively, joined in each case through a common P2-bridge. Thus, 1 is 6,7,9,16,17,20-hexaisopropyloctacyclo[10.8.0.0(2,14).0(3,11).0(4,8).0(5,10).0(13,18).0(15,19)]icosaphosphane and 2 is 7,9,15,17,19,20-hexaisopropyl-octacyclo[14.2.1.1(5,8).0(2,14).0(3,12).0(4,10).0(6,11).0(13,18)]icosaphosphane. The phosphorus hydrogen compound P20H6 [22, 2c] should exhibit the same constitutional isomerism.