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Structural Study of the Conformational Isomers of (η 4 ‐Benzylideneacetone)‐ and (η 4 ‐Diene)Fe(CO) 2 L Complexes by Inverse Triple‐Resonance Iron‐57 NMR
Author(s) -
Rentsch Gudrun Hopp,
Nanz Daniel,
Solana Isabel,
Stefanova Raina,
von Philipsborn Wolfgang
Publication year - 1996
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199612)34:12<1036::aid-omr20>3.0.co;2-1
Subject(s) - chemistry , chemical shift , conformational isomerism , coupling constant , resonance (particle physics) , diene , nuclear magnetic resonance spectroscopy , crystallography , stereochemistry , nuclear magnetic resonance , molecule , organic chemistry , physics , natural rubber , particle physics
For the first time, 2D( 31 P, 57 Fe){ 1 H}‐triple‐resonance NMR spectroscopy was used at low temperatures (213 and 179 K) to study the conformers of (η 4 ‐benzylideneacetone)‐ and (η 4 ‐diene)Fe 0 (CO) 2 L complexes (L = phosphanes, phosphites). In some cases not only the 57 Fe chemical shifts and the 1 J ( 57 Fe, 31 P) coupling constants of the major isomer but also those of a less populated isomer were determined. Based on earlier 31 P and 13 C NMR and molecular orbital studies of the complexes, the trends of the 57 Fe chemical shifts are discussed in terms of the paramagnetic shielding constant. For both series investigated the apical conformers (compared with the basal) exhibit the more shielded iron nuclei and the larger 57 Fe, 31 P coupling constants indicating stronger coordination of the phosphorus ligands in the apical position.