Inner-Sphere versus Outer-Sphere Coordination of BF4– in a NHC-Gold(I) Complex
AuthorsVeenboer, Richard M. P.
Cordes, David B.
Slawin, Alexandra M. Z.
Cazin, Catherine S. J.
Nolan, Steven P.
KAUST DepartmentKAUST Catalysis Center (KCC)
Physical Sciences and Engineering (PSE) Division
Chemical Science Program
Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
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AbstractThe role of counterions in chemistry mediated by gold complexes stretches much further than merely providing charge balance to cationic gold species. Interplay between their basicities and coordination strengths influences interactions with both the gold center and substrates in catalysis. Actual monogold(I) active species are generally believed to be monocoordinated species, formed from the abstraction or the decoordination of a second ligand from precursor complexes, but only a small amount of experimental evidence exists to underpin the existence of these transient species. The formation of a bench-stable neutral IPrCl-gold(I) tetrafluoroborate complex is reported herein. Experimental studies by X-ray diffraction analysis and NMR spectroscopy and theoretical studies by DFT calculations were conducted to determine the composition, structure, and behavior of this complex. The absence of an auxiliary ligand resulted in inner-sphere coordination of the counterion in the solid state. In solution, an equilibrium between two conformations was found with the counterion occupying inner-sphere and outer-sphere positions, respectively. Stoichiometric and catalytic reactivity studies with the tetrafluoroborate complex have been conducted. These confirmed the lability of the inner-sphere coordinating counterion that gives the IPrCl-gold(I) fragment behavior similar to that of related systems.
CitationVeenboer RMP, Collado A, Dupuy S, Lebl T, Falivene L, et al. (2017) Inner-Sphere versus Outer-Sphere Coordination of BF4– in a NHC-Gold(I) Complex. Organometallics 36: 2861–2869. Available: http://dx.doi.org/10.1021/acs.organomet.7b00345.
SponsorsThe European Research Council (ERC) and the Engineering and Physical Sciences Research Council (EPSRC) are gratefully acknowledged for their support. S.P.N. and L.C. thank King Abdullah University of Science and Technology (KAUST) for support. Dr. Filippo Stella is thanked for his help with NMR experiments. This publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No. OSR-2015-CCF-1974-03.
PublisherAmerican Chemical Society (ACS)