Synthese und Molekülstruktur chiraler Bis(1,3,2‐dioxaphospholane)

Synthesis and Molecular Structure of Chiral Bis(1,3,2‐dioxaphospholanes) Bisphosphites of the general type C₂O₂POC_nOPO₂C₂ containing chiral building blocks both in the five‐membered C₂O₂P rings and in the OC_nO bridge were prepared from 2‐chloro‐1,3,2‐dioxaphospholanes and chiral diols in the presence of a base. The molecular structure of compound 10 , which was obtained from 2‐chloro‐(4R,5R)‐4,5‐dimethyl‐1,3,2‐dioxaphospholane and (R)‐1,1′‐binaphthalin‐2,2′‐diol, was determined by X‐ray crystallography.     

Synthese und Molekülstruktur zweier 1-Sila-3-alanata-cyclobutan-Derivate mit AlC2Si-Heterozyklus

Synthesis and Molecular Structure of Two 1-Sila-3-alanata-cyclobutane Derivatives with Four-membered AlC₂Si-Heterocycles The C? H acidic bis(trimethylsilyl)methyl compounds Me₃C? AlR₂ und Me₃C? CH₂? AlR₂ (R ? CH(SiMe₃)₂) are deprotonated by treatment with the sterically high shielded base LiCH(SiMe₃)₂ in the presence of 1,3,5-trimethylhexahydrotriazinane. The deprotonation occurs at a methyl group of one of the element-organic substituents, and the formed carbanions are stabilized by coordination to the unsaturated Al atoms yielding four-membered heterocycles. Both products were characterized by a crystal structure determination each showing bent ring systems.     

Synthese und Molekülstruktur neuer Ringsysteme aus 1,1,3,3-Tetrachlor-1,3-diphosphapropan

Synthesis and Molecular Structure of new Ring Systems from 1,1,3,3-Tetrachloro-1,3-diphosphapropane 1,1,3,3-Tetrachloro-1,3-diphosphapropane 1 reacts in two different ways to form new heterocycles. Partial oxidation of 1 with tetrachloroorthobenzoquinone furnishes the methylene-bridged λ³P, λ⁵P species 3 . Subsequent reactions with di- and triethylamine lead to the condensed ring system 6 with the P?C bonds connected to a central four-membered ring. Compound 6 displays crystallographic inversion symmetry, a short transannular P? P distance and an extremely distorted tetrahedral coordination geometry at the four-membered ring phosphorus atoms. 1 reacts with 7 to give the heterocycle 8 with a central eight-membered ring involving four phosphorus atoms. The eight – membered ring shows a ?bent”? crown conformation, the condensed five – membered rings display envelope conformation.     

Die Kristall- und Molekülstruktur von 1,1,3,3-Tetraphenyl-2,4-bis(triphenylphosphonio)−1λ5,3λ5-diphosphacyclobutadien-dinitrat7hyphenl;hydrat

Crystal and molecular structure of 1,1,3,3-tetraphenyl-2,4-bis(triphenylphosphonio)-1⁵,3lambda;⁵-diphosphacyclobutadiene Dinitrate Hydrate [(C₆H₅)₃PCP(C₆H₅)₂]₂(NO₃)₂ · H₂O is monoclinic (P2₁/n) with a = 12.173 (15), b = 15.583 (3), c = 14.353 (17) Å, β = 102.86 (3)7deg;, Z = 2. The structure was solved by direct methods and refined by least squares to R = 0.062. The compound contains the centrosymmetric cation The bond distances in the four-membered ring and to the exocyclic P atoms show that the delocalization of the double bonds (or the positive charges) extends over the exocyclic P atoms, too.