Beiträge zur Chemie des Phosphors, 103 [1, 2]. Tri-tert-butyl-diphosphaarsa-cyclopropan, (t-BUP)2 (t-BuAs) / Contributions to the Chemistry of Phosphorus, 103 [1, 2]. Tri-tert-butyl-diphosphaarsa-cyclopropane, (t-BuP)2(t-BuAs)

Abstract

The first three-membered P₂AS heterocycle, tri-tert-butyl-diphosphaarsa-cyclopropane (tri-tert-butyl-diphosphaarsirane) (1) was synthesized by [2+1] cyclocondensation of K(t-Bu)P-P(t-Bu)K with t-BuAsCl₂ in n-pentane at - 78 °C. Tetra-tert-butyl-1,2-di-phospha-3,4-diarsa-cyclobutane (2), tetra-tert-butyl-triphosphaarsa-cyclobutane (3) as well as (t-BuP)₄ and five-membered cycloarsaphosphanes are also formed. The diphospha-arsa-cyclopropane 1 could be isolated in a pure state. It forms two diastereomers, of which the isomer with trans-orionted tert-butyl groups at the phosphorus atoms is the most stable. The ³¹P NMR parameters of the four-membered cycloarsaphosphanes 2 and 8 are reported