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Enantiomerically Pure Pentadienyl Rhodium(I) and Iridium(I) Complexes – Their Synthesis and Reactivity
Author(s) -
Fecker Ann Christin,
Münster Katharina,
Freytag Matthias,
Jones Peter G.,
Walter Marc D.
Publication year - 2019
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.201900702
Subject(s) - chemistry , moiety , iridium , ligand (biochemistry) , delocalized electron , rhodium , reactivity (psychology) , molecule , coordination complex , crystallography , nuclear magnetic resonance spectroscopy , infrared spectroscopy , stereochemistry , metal , organic chemistry , catalysis , medicine , biochemistry , receptor , alternative medicine , pathology
Reactions of [(η 4 ‐COD)M(µ‐Cl)] 2 (M = Rh, Ir) with the potassium pentadienides (KPdl*) derived from (1 R )‐(–)‐myrtenal allowed the corresponding enantiomerically pure Rh I and Ir I compounds [(η 4 ‐COD)M(η 5 ‐Pdl*)] to be isolated. Full characterization of these species was accomplished by NMR spectroscopy, elemental analysis and X‐ray diffraction studies. Notably, the coordination modes of the Pdl* ligands vary in the solid‐state structure of the Ir and Rh compounds. While η 5 ‐ U coordination with a fully delocalized negative charge within the Pdl* moiety was achieved in the Ir I derivatives, the structures for the Rh I analogues are best described by a η 3 :η 2 ‐ U coordination in which the metal slips into an allyl–ene structure. Furthermore, while only one species was observed for the Ir I compounds in solution consistent with their molecular structures established in solid state, the solution behavior of the Rh I derivatives is more complex. In these cases a mixture of isomers, which are in chemical equilibrium with each other, are observed. The major isomer exhibits NMR signatures that are in line with the solid‐state structures of these molecules. The minor component, however, is derived from a rotation of the myrtenal moiety to yield a η 3 ‐ S coordinated Pdl* ligand. Exposure of [(η 4 ‐COD)Ir(η 5 ‐Pdl*)] to H 2 rapidly forms Ir (nano)particles, resulting from the initial hydrogenation of the Pdl* moiety. Intermediates with a partially hydrogenated Pdl*‐ligand were successfully isolated.