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

Abstract

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 abstraction lead to the air-stable cationic complex [(NHC-Ox)-Rh(nbd)]PF 6 (4) with the expected bidentate coordination

Redox Chemistry of Pt(II) Complex with Non-Innocent NHC Bis(Phenolate) Pincer Ligand: Electrochemical, Spectroscopic, and Computational Aspects

“…Thus, the pyridine ligand occupies the coordination site trans to the pincer carbene carbon, while two oxygen atoms complete the metal coordination sphere standing trans to each other. The Pt−C carbene distance (1.954(2) Å) falls in the same range as those observed for related structures [30,[52][53][54][55][56]. A significant distortion of the planarity of the {OCO}Pt moiety of the complex is observed An EPR analysis of a solution of [Pt(L)Py][BF4] in CH2Cl2 at 298 K shows a signal at g = 2.070 with signal coupling coming from the 195 Pt having nuclear spin of 1 /2 and natural content of 33.775%.…”

Synthesis, Characterization, Photoluminescence, and Simulations of a CCC-NHC-Supported Pt2Ag2 Mixed-Metal Cluster Containing a PtAg2 Metallacyclopropane

“…In the solid state complex 2 adopted C 2 symmetry along the C aryl –Pt–Cl axis and was close-packed in the C 2/ c space group. The Pt–C NHC bond distance in 2 , 2.024(3) Å, falls in the range observed for neutral and cationic Pt(II) NHC complexes. ,, The Pt–C aryl bond length, 1.929(3) Å, was ∼0.15 Å shorter than the Pt–C aryl bond lengths in monodentate complexes . The coordination sphere of Pt(II) in complex 2 was a distorted-square-planar configuration, which is commonly seen for four-coordinated Pt(II) complexes. , The C aryl –Pt–Cl atoms were linear (180°).…”

N‐Heterocyclic Carbenes with Neutral Tethers

“…However, the comparatively small and infl exible bite angle [ 51 -53 ] limits the ligand ' s compatibility with a large range of potential catalyst metals [ 100 ]. One important consideration is the rigidity of the ligand scaffold.…”

“…Although introduction of a linker unit provides greater fl exibility of the ligand in terms of accessibility of more transition metal fragments, this fl exibility is bought at the expense of rigidity in the ligand backbone [ 100 ]. As the rigidity is a key factor in the regio -and stereoselectivity of the ensuing transition metal complex in catalysis, introduction of a more fl exible linker unit generally results in decreased catalytic performance.…”