Die Struktur des 2.3.4.6.7.8-Hexamethyl-2.3.4.6.7.8-hexaphosphabicyclo- [3.3.0] octans (PMe)₆C₂H₂ / The Structure of 2,3,4,6,7,8-Hexamethyl-2,3,4,6,7,8-hexaphosphabicyclo[3,3,0]octane (PMe)₆C₂H₂

Abstract

<jats:title>Abstract</jats:title><jats:p> One of the diastereomeres of 2,3,4,6,7,8-hexamethyl-2,3,4,6,7,8-hexaphosphabicyclo-[3,3,0]octane (PMe)<jats:sub>6</jats:sub>C<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub> crystallizes in the space group P2<jats:sub>1</jats:sub>/n with four molecules per unit cell. Two independent molecules are nearly identical in shape but differ by inter-molecular packing. The five-membered rings have a skew chair conformation with all exocyclic methyl groups in axial positions leading to a staggered all-trans conformation of the bicyclic system. The mean bond lengths are P-P = 220.9 pm, P-C = 185.9 pm and C-C = 151.9 pm.</jats:p>

P–N/P–P Bond Metathesis for the Synthesis of Complex Polyphosphanes

“…In contrast, hexaphosphanes 2a and 2b display a gauche conformation resulting in increased steric repulsion and thus in larger bond angles. Similar to other structurally characterized 1,2,3-triphosphacyclopentane derivatives, a twist ( 4 T 5 ) , conformation is observed for the 1,2,3-triphosphacyclopentane rings (Figure A , B ) . The substituents on this fragment adopt an all-trans arrangement (Figure , A ).…”