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13 C, 17 O and 55 Mn NMR studies on substituted manganese carbonyl complexes. A contribution to the mechanism of demetalation reactions
Author(s) -
Rentsch Daniel,
Nill Lilan,
von Philipsborn Wolfgang,
Sidler D. Richard,
Rybczynski Philip J.,
DeShong Philip
Publication year - 1998
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(199806)36:13<s54::aid-omr292>3.0.co;2-l
Subject(s) - chemistry , manganese , mechanism (biology) , carbon 13 nmr , reaction mechanism , computational chemistry , photochemistry , polymer chemistry , stereochemistry , organic chemistry , catalysis , philosophy , epistemology
13 C and 17 O chemical shifts and 55 Mn, 13 C coupling constants of nine pentacarbonylmanganese complexes RMn(CO) 5 ( 6 – 14 ), 13 tetracarbonylmanganese complexes RMn(CO) 4 PR 3 ′ ( 15 – 27 ) and five tetracarbonylmanganacycle complexes (1a–e) were determined and are discussed in terms of σ‐inductive substituent effects on axial and equatorial CO ligands. Linear correlations are observed between σ I (R) and δ( 13 C) of equatorial CO ligands and δ( 17 O) of axial CO ligands, respectively. In the tetracarbonylmanganacycle complexes 1a – e the 17 O chemical shifts of the axial (CO) a ligands exhibit the largest substituent effect ( trans influence), they correlate with the rates log k obs of the demetalation reaction and the mechanistic implications are discussed. The 55 Mn, 13 C coupling constants of the axial (CO) a ligands (144–159 Hz) likewise show a large and steady substituent dependence. © 1998 John Wiley & Sons, Ltd.