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

<jats:p>The first three-membered P<jats:sub>2</jats:sub>AS 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-BuAsCl<jats:sub>2</jats:sub> 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)<jats:sub>4</jats:sub> 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 <jats:sup>31</jats:sup>P NMR parameters of the four-membered cycloarsaphosphanes 2 and 8 are reported </jats:p>

Selective Reductions of N,N‐Bis{chloro(aryl)‐phosphino}‐amines Yielding Three‐, Five‐, Six‐, and Eight‐Membered Cyclic Azaphosphanes

“…In an in situ 31 P NMR spectrum of the reduction of 1 c with [Cp 2 Ti(η 2 ‐btmsa)], only one singlet at −75 ppm could be detected. This highfield‐shifted value is characteristic for azadiphosphiridines, which normally resonate in the range −44 to −86 ppm in 31 P NMR spectroscopy . Similar to that mentioned by Baudler for cyclotriphosphanes, it could be an effect of the small ring and a consequence of the predominant s character and, therefore, good shielding of the free electron pair at the phosphorus atom .…”

“…in 1982. However, they were neither able to observe the formation of an azadiphosphiridine nor to identify any other cyclic compounds …”