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Stereoisomerism of bis(σ‐Zincane) Complexes: Evidence for an Intramolecular Pathway
Author(s) -
Ekkert Olga,
White Andrew J. P.,
Crimmin Mark R.
Publication year - 2017
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.201701207
Subject(s) - intramolecular force , stereoisomerism , chemistry , stereochemistry , biochemistry , catalysis
The first bis(σ‐zincane) complexes, heterotri‐ metallic species [M(CO) 4 (η 2 ‐HZnBDI) 2 ], have been prepared (BDI=κ 2 ‐{2,6‐( i Pr) 2 C 6 H 3 NCMe} 2 CH). For M=Cr, a single stereoisomer is observed in solution and the solid‐state. For M=Mo and W, cis and trans isomers were found to reversibly interconvert at 297 K. Despite the huge steric demands of the ligand on zinc, the cis isomer was found to be the most thermodynamically stable in all cases. The activation parameters for the isomerisation when M=Mo are Δ H ≠ =20.8 kcal mol −1 and Δ S ≠ =−12.8 cal K −1 mol −1 . In combination with DFT calculations, the negative activation entropy suggests an intramolecular rotation mechanism for isomerisation.