Diiron Dithiolate Hydrides Complemented with Proton-Responsive Phosphine–Amine Ligands

Michaela R. Carlson, Ryan Gilbert-Wilson, Danielle R. Gray, Joyee Mitra, Thomas B. Rauchfuss, Casseday P. Richers

Research output: Contribution to journalArticlepeer-review


The reaction of Fe2(pdt)(CO)6 with two equivalents of Ph2PC6H4NH2 (PNH2) affords the amido hydride HFe2(pdt)(CO)2(PNH2)(PNH) {[H1H]0, pdt2– = CH2(CH2S)2}. Isolated intermediates in this conversion include Fe2(pdt)(CO)51-PNH2) and Fe2(pdt)(CO)42-PNH2). X-ray crystallographic analysis of [H1H]0 shows that the chelating amino/amido–phosphine ligands occupy trans-dibasal positions. The 31P NMR spectrum indicates that [H1H]0 undergoes rapid proton exchange between the amido and amine centers. No exchange was observed for the hydride. Protonation of [H1H]0 gives [HFe2(pdt)(CO)2(PNH2)2]+ ([H21H]+), which contains two equivalent amino–phosphine ligands. Single-crystal X-ray crystallographic analysis of [H21H]+ also reveals hydrogen bonds between the exo amine protons with a THF molecule and BF4. Deprotonation of [H1H]0 with potassium tert-butoxide gave [HFe2(pdt)(CO)2(PNH)2] ([1H]), which was characterized spectroscopically. The complex has time-averaged C2 symmetry with two amido–phosphine ligands. FTIR spectroscopic measurements show that υCO shifts by approximately 20 cm–1 in the series [1H], [H1H]0, and [H21H]+. These shifts are comparable to those seen for the S-protonation of the (NC)2(CO)Fe(µ-Scys)2Ni(Scys)2 site in the [NiFe]-hydrogenases.

Original languageEnglish (US)
Pages (from-to)3169-3173
Number of pages5
JournalEuropean Journal of Inorganic Chemistry
Issue number25
StatePublished - 2017


  • Amido ligands
  • Hydrides
  • Hydrogenases
  • Iron
  • Oxidative addition

ASJC Scopus subject areas

  • Inorganic Chemistry


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