Abstract We report the synthesis and spectroscopic characterization of a series of iron‐carbene complexes in redox states {Fe=C(H)Ar}10–11. Pulse EPR studies of the1,2H and13C isotopologues of {Fe=C(H)Ar}11reveal the high covalency of the Fe–carbene bonding, leading to a more even spin distribution than commonly observed for reduced Fischer carbenes. 
                        more » 
                        « less   
                    
                            
                            Directed C–H activation with iron carbene complexes
                        
                    
    
            The reactivity of PCcarbeneP iron carbenes, was investigated toward imines, ketones, diazenes, 2-vinylpyridine, and 8-methylquinoline, revealing the directed activation of aryl, vinyl, or benzyl C–H bonds by 1,2-addition across the iron-carbene bond. 
        more » 
        « less   
        
    
                            - Award ID(s):
- 2102517
- PAR ID:
- 10573524
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- Inorganic Chemistry Frontiers
- Volume:
- 11
- Issue:
- 17
- ISSN:
- 2052-1553
- Page Range / eLocation ID:
- 5579 to 5586
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
- 
            
- 
            Previous work has demonstrated that variants of a heme protein, Rhodothermus marinus cytochrome c (Rma cyt c), catalyze abiological carbene boron–hydrogen (B–H) bond insertion with high efficiency and selectivity. Here we investigated this carbon–boron bond-forming chemistry with cyclic, lactone-based carbenes. Using directed evolution, we obtained a Rma cyt c variant BORLAC that shows high selectivity and efficiency for B–H insertion of 5- and 6-membered lactone carbenes (up to 24,500 total turnovers and 97.1:2.9 enantiomeric ratio). The enzyme shows low activity with a 7-membered lactone carbene. Computational studies revealed a highly twisted geometry of the 7-membered lactone carbene intermediate relative to 5- and 6-membered ones. Directed evolution of cytochrome c together with computational characterization of key iron-carbene intermediates has allowed us to expand the scope of enzymatic carbene B–H insertion to produce new lactone-based organoborons.more » « less
- 
            Abstract A simple experimental procedure for scaling carbene Brønsted basicity is described. The results highlight the strong basicity of pyrazol‐4‐ylidenes, a type of mesoionic carbene, also named cyclic‐bentallenes (CBA). They are more basic (pKaH>42.7 in acetonitrile) than the popular proazaphosphatrane Verkade bases, and even the Schwesinger phosphazene superbase P4(tBu). The basicity of these compounds can readily be tuned, and they are accessible in multigram quantities. These results open new avenues for carbon centered superbases.more » « less
 An official website of the United States government
An official website of the United States government 
				
			 
					 
					
 
                                    