A bonding model for gold(I) carbene complexes.
The last decade has witnessed dramatic growth in the number of reactions catalyzed by electrophilic gold complexes. While proposed mechanisms often invoke the intermediacy of gold-stabilized cationic species, the nature of bonding in these intermediates remains unclear. Herein, we propose that the carbon-gold bond in these intermediates is comprised of varying degrees of both sigma and pi-bonding; however, the overall bond order is generally less than or equal to unity. The bonding in a given gold-stabilized intermediate, and the position of this intermediate on a continuum ranging from gold-stabilized singlet carbene to gold-coordinated carbocation, is dictated by the carbene substituents and the ancillary ligand. Experiments show that the correlation between bonding and reactivity is reflected in the yield of gold-catalyzed cyclopropanation reactions.
Benitez
Diego
D
Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125 USA.
Shapiro
Nathan D
ND
Tkatchouk
Ekaterina
E
Wang
Yiming
Y
Goddard
William A
WA
Toste
F Dean
FD
D003521:Cyclopropanes / Q000138:chemical synthesis / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D008024:Ligands; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D050607:Organogold Compounds / Q000737:chemistry*
D003521:Cyclopropanes; D008024:Ligands; D050607:Organogold Compounds; C030011:carbene; D006046:Gold; D008697:Methane