Ligands ketone

A number of chelating ketone ligands are reported in Section 6.8.11. Due to the weak binding, chelation helps to stabilize the complexes and there are few structural examples of monodentate ketone ligands. 

The X-ray structures are known of a number of ketone ligands, including hexanedione and 4-methylcyclohexanone, that have bound as monodentate ligands in the fifth coordination site of zinc porphyrin complexes.347,348 Oxaphlorin dimeric compounds are also known where the oxygen from a neighboring porphyrin ring coordinates in the fifth coordination site of a neighboring zinc porphyrin unit.349... 

The key step involves C-H bond activation, and produces a molybdenum complex with hydride and ketone ligands from the alkoxide ligand. Subsequent... 

In contrast to electrophiles, nucleophiles are expected to react preferentially with n -bonded heteroaldehyde and -ketone ligands. The site of attack is expected to be the carbon atom of the E = C group, -coordinated ligands should be less reactive. 

Ketone Ligand Rh-cat.r L/Rh S/Cd Solvent Temp/Time (°C/h) Product alcohol Ref. 

Figure 7.1. Postulated transition structures for the asymmetric reduction of unsaturated ketones by BINAL-H [12]. Structures (a) and (b) differ in the orientation of Rjat and Run, the saturated and unsaturated ketone ligands, respectively, (a) UI topicity P reagent attacking Re face of ketone, (b) Lk topicity P reagent attacking Si face of ketone, (c) Alternate chair that is destabilized by the gauche pentane conformation accented by the bold lines (c/. Figure 5.5). Transition structures containing this conformation were considered by Noyori to be unimportant [12].

To further explore the complementary shape approach developed by Swager and co-workers (vide supra), several hemi-disk-shaped compounds, related structurally to the diketonato metal complexes (58) discussed above in which two ketonate ligands are connected through a diamino link, have been prepared. Systematic modifications of the chemical structures were carried out in order to understand some structure-property relationships, and the extension of the validity of such concepts. Such /3-enaminoketonato ligands were, however, promising systems for columnar mesophase induction due to their better planarity compared to the /3-diketonato structures. 

Silane Ketone Ligand in 5 or 6 Optical yield (%) (configuration) Reference... 

For other metals with analogous ligand sets, the situation remains uncertain, with most of the mechanistic inferences coming from theory. Results for Rh have been discussed already. Meijer and co-workers have done a theoretical comparison of (T -arene)Ru and (l,5-COD)Ir systems with amino alcohol and amino thiol chelates. They concluded that the Ru system uses the bifunctional mechanism, but the Ir system proceeds by direct transfer with chelate ring opening to accommodate the alcohol and ketone ligands and no formation of a hydride. 

Co(2,2 -CsH4N CO C5H4NKH2O) (CH3C00-)2 room 9290c. 4.70 pseudo-octahedral coordination suggested possibly hydration of the ketone group of di(2-pyridyl)ketone ligand 7408... 

Another elegant route for the room-temperature coupling of aryl iodide (of aryl bromides at 65°C) with aliphatic amides was developed by Ding et al. with the support of a 2 pyridyl p-ketones ligand L21. This Cu-based catalytic system permits... 

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