A New Class of Modular Oxazoline-NHC Ligands and Their Coordination Chemistry with Platinum Metals

• Published in: European Journal of Inorganic Chemistry Vol. 2008; no. 36; pp. 5587 - 5598
• Main Authors: Schneider, Nathanaëlle, Bellemin-Laponnaz, Stéphane, Wadepohl, Hubert, Gade, Lutz H.
• Format: Book Review Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.12.2008; WILEY‐VCH Verlag; Wiley; Wiley-VCH Verlag
• Subjects: Carbenes; Chemical Sciences; Chemistry; Chemistry, Inorganic & Nuclear; Oxazolines; Physical Sciences; Platinum; Rhodium; Science & Technology; ASYMMETRIC CATALYSIS; HYDROGENATION; Oxazolines; N-HETEROCYCLIC-CARBENE; RHODIUM(I) COMPLEXES; STABLE CARBENES; REACTIVITY; HYDROSILYLATION CATALYSTS; Carbenes; THREEFOLD SYMMETRY; Rhodium; Platinum; STEREODIRECTING LIGANDS; EFFICIENT
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.200800908

A novel family of enantiomerically pure imidazolium salts [(NHC‐Ox)H]+X– (2a–g) has been generated bearing an oxazoline unit and in which both heterocycles are connected by a (dimethyl)methylene bridge. Deprotonation of the imidazolium salt 2f and subsequent reaction of the resulting free carbene with [Rh(nbd)Cl]2 (nbd = norbornadiene) afforded the neutral rhodium(I) complex [(NHC‐Ox)Rh(nbd)Br] (3) in which the ligand was found to be monodentate. Bromide ion lead to the air‐stable cationic complex [(NHC‐Ox)Rh(nbd)]PF6 (4) with the expected bidentate coordination mode of the ligand. Reaction of the imidazolium salt 2d with Karstedt's catalyst and one equivalent of KOtBu gave the trigonal planar platinum(0) complex [(NHC‐Ox)Pt(dvtms)] (5) (dvtms = divinyltetramethylsiloxane), which was oxidized by CsBr3 to give the square planar platinum(II) complex [(NHC‐Ox)PtBr2] (6). Complex [(NHC‐Ox)PtCl2] (7) was directly prepared by reaction of the imidazolium salt with Ag2O followed by the addition of [PtCl2(1,5‐cod)]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) A novel family of enantiomerically pure imidazolium salts has been generated bearing an oxazoline unit and in which both heterocyles are connected by a (dimethyl)methylene bridge. The coordination behavior of the corresponding carbenes has been investigated by preparing Rh and Pt complexes.