Gauging the donor strength of iron(0) complexes via their N-heterocyclic carbene gold(I) adducts

Zhi Hao Toh; Hendrik Tinnermann; Dinh Cao Huan Do; Han Vinh Huynh; Tobias Krämer; Rowan D Young

doi:10.1039/d2cc05041b

Gauging the donor strength of iron(0) complexes via their N-heterocyclic carbene gold(I) adducts

Chem Commun (Camb). 2022 Nov 22;58(93):12947-12950. doi: 10.1039/d2cc05041b.

Authors

Zhi Hao Toh¹, Hendrik Tinnermann¹, Dinh Cao Huan Do¹, Han Vinh Huynh¹, Tobias Krämer², Rowan D Young¹

Affiliations

¹ Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore. rowan.young@nus.edu.sg.
² Department of Chemistry, Maynooth University, Maynooth, Co. Kildare, Ireland.

PMID: 36321577
DOI: 10.1039/d2cc05041b

Abstract

We isolate and characterize the gold(I)-iron(0) adducts [(ⁱPr₂-bimy)Au-Fe(CO)₃(PMe₃)₂][BAr^F₄] and [Au-{Fe(CO)₃(PMe₃)₂}₂][BAr^F₄] (ⁱPr₂-bimy = 1,3-diisopropylbenzimidazolin-2-ylidene, BAr^F₄ = tetrakis(pentafluorophenyl)borate). DFT analysis reveals that the gold-iron interaction in [(ⁱPr₂-bimy)Au-Fe(CO)₃(PMe₃)₂][BAr^F₄] is predominantly a σ-donation from iron to gold. We further extend this class of compounds to include [(ⁱPr₂-bimy)Au-Fe(CO)₃(PR₃)₂][BAr^F₄] (PR₃ = PPh₃, PCy₃, PCyPh₂, PMePh₂, PMe₂Ph, P(4-C₆H₄F)₃) and [(ⁱPr₂-bimy)Au-Fe(CO)₄(PPh₃)][BAr^F₄] and correlate the ⁱPr₂-bimy carbenic ¹³C NMR signal with the relative donor strength of the iron(0) ligand. This approach allows for a fast and simple approach to gauge relative donor strength of Fe(0) donors.