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Syntheses and Characterization of (C 2 F 5 ) 3 BCO and (C 3 F 7 ) 3 BCO
Author(s) -
Gerken Michael,
Pawelke Gottfried,
Bernhardt Eduard,
Willner Helge
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201000211
Subject(s) - triple bond , borane , bond cleavage , yield (engineering) , crystal structure , bond length , crystallography , chemistry , sulfuric acid , stereochemistry , double bond , materials science , inorganic chemistry , organic chemistry , catalysis , metallurgy
The new tris(perfluoroalkyl)borane carbonyls, (C 2 F 5 ) 3 BCO and (C 3 F 7 ) 3 BCO, were prepared by means of a novel synthetic route using commercially available precursors by reacting K[(C 2 F 5 ) 3 BCOOH] and K[(C 3 F 7 ) 3 BCOOH] with concentrated sulfuric acid in the last step. The carboxylic acids, K[(C 2 F 5 ) 3 BCOOH] and K[(C 3 F 7 ) 3 BCOOH], were prepared by oxidative cleavage of the CC triple bonds in Cs[(C 2 F 5 ) 3 BCCPh] and Cs[(C 3 F 7 ) 3 BCCPh] in a two‐step process to yield K[(C 2 F 5 ) 3 BCOCOPh] and K[(C 3 F 7 ) 3 BCOCOPh] as isolable intermediates. Crystal structures were obtained of K[(C 2 F 5 ) 3 BCOCOPh], K[(C 2 F 5 ) 3 BCOOH] ⋅ H 2 O, (C 2 F 5 ) 3 BCO, K[(C 3 F 7 ) 3 BCOOH] ⋅ 2 H 2 O, and (C 3 F 7 ) 3 BCO. In the crystal structures of (C 2 F 5 ) 3 BCO and (C 3 F 7 ) 3 BCO the CO bond lengths are 1.109(2) and 1.103(5) Å, respectively, which are among the shortest observed to date. Tris(pentafluoroethyl)borane carbonyl and (C 3 F 7 ) 3 BCO slowly decompose at room temperature to yield CO, difluoroperfluoroalkylboranes and perfluoroalkenes. The decomposition of (C 2 F 5 ) 3 BCO was found to follow a first‐order rate law with E a =107 kJ mol −1 .