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Dihalides of Sterically Constrained Tricyclic Phosphines, Lewis Acidity and Fluoride Affinity, Chloride Abstraction, and a Phosphonium Cation, Dimethylphosphorane
Author(s) -
Brand Alexander,
Hentschel Anne,
Hepp Alexander,
Uhl Werner
Publication year - 2020
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201901231
Subject(s) - chemistry , phosphonium , steric effects , phosphorane , trigonal bipyramidal molecular geometry , medicinal chemistry , lewis acids and bases , square pyramidal molecular geometry , moiety , hypervalent molecule , fluoride , stereochemistry , crystal structure , crystallography , polymer chemistry , organic chemistry , inorganic chemistry , reagent , catalysis
Treatment of the trilithium compounds 3 with PCl 3 afforded sterically constrained tricyclic phosphines with annulated five‐ (2 ×) and six‐membered rings and the P atoms in the bridgehead positions ( 2a , vinylic SiMe 2 Ph; 2b , vinylic SiMe 3 groups). Their AuCl complexes ( 4 ) were used for an estimation of the buried volumes ( 4b : % V = 46 %). Reactions of 2b with XeF 2 or SO 2 Cl 2 afforded PX 2 derivatives [X = F ( 5b ), Cl ( 6b )]. Crystal structure determinations including the recently reported difluorides and diiodides of 2a ( 5a and 7 ) allow a systematic comparison of structural details. The P atoms have trigonal bipyramidal to square pyramidal surroundings. The PF 2 phosphorane 5a behaves as a Lewis acid and coordinates F – to yield a phosphate anion ( 8 ) with a PF 3 C 3 molecular centre, while Cl – abstraction from 3a afforded an unstable phosphonium cation ( 9 ). Unusual methylphosphoranes with one or two methyl groups attached to phosphorus were obtained by reactions of the dihalides 5a or 6a with methyllithium.