Structure and Reactivity of Dinitrogen Rhodium Complexes Containing N‐Heterocyclic Carbene Ligands

Abstract

The rhodium bis-carbene complex [Rh(IPr) 2 (N 2 )Cl], where IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, has been synthesized and characterized. The complex is a rare example of a four-coordinate rhodium complex featuring nitrogen bound end-on. While quite stable as a solid under inert atmosphere, in solution the N 2 ligand has been found to be quite labile. This lability has been exploited in the synthe-

N‐Heterocyclic Carbene Rhodium Complexes and Their Reactions with H2 and with CO

“…Crudden and co-workers have synthesized complex 5 from the nitrogen complex trans-RhCl(N 2 )(IPr) 2 , and have also obtained a crystal structure for 5 which co-crystallized with the Rh II complex RhCl 2 (IPr) 2 ; their determined crystallographic geometrical parameters for a non-solvated crystal of 5 are close to our values, and they were able also to locate the hydrides (Rh-H = 1.45 Å). [23] In attempts to make hydrido, mixed-NHC complexes, reactions of [RhCl(COE)(IPr)] 2 (1) with 1 equiv. of IMes per Rh were examined.…”

“…[27] A crystal structure of complex 8 (synthesized from transRhCl(N 2 )(IPr) 2 ) is reported elsewhere in an article in this journal issue. [23] …”

“…[22] During the writing of this paper, we heard that Crudden's group had also been studying reactivity of H 2 , CO, and N 2 , toward the same NHC-Rh I species, and their work (with necessarily some overlap) is reported in this journal issue. [23] Scheme 1. Reactions of 1 and 2 with H 2 .…”

Double Single‐Crystal‐to‐Single‐Crystal Transformation and Small‐Molecule Activation in Rhodium NHC Complexes

“…In particular, we were interested in the use of NHCs for their increased oxidative stability in comparison to phosphines. In particular, we and others have been interested in the reaction of rhodium complexes of bulky, electron‐rich ligands with O 2 9a,c. 12 Interestingly, these types of ligands seem to promote the formation of what can best be described as rare examples of pseudo square‐planar rhodium(I) complexes of singlet oxygen ( 2 )…”

Synthesis, Structure, and Reactivity of Rhodium Bipyridine Compounds: Formation of a RhII Hydrido Cluster and a RhIII Peroxido Complex

“…It is therefore desirable to synthesize rhodium peroxido compounds that do not include any phosphanes as additional ligands. So far, only a limited number of these compounds have been reported, including complexes with N‐heterocyclic carbene ligands 10,13. Cationic rhodium peroxido complexes that contain tetradentate tri(2‐pyridylmethyl)amine ligands have also been described 14.…”