Compound 3
[(Anth·CNHNS)Fe(CO)2(THF)](BARF)
From: Structural and functional synthetic model of mono-iron hydrogenase featuring an anthracene scaffold
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Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.
A small batch of 11 mg (18 µmol) of complex 1 and 19 mg (18 µmol) of [Tl](BArF) was each prepared separately in 0.3 mL of d8-THF at -30 °C. The two solutions were mixed at -30 °C and gradually warmed to room temperature to generate [(Anth•CNHNS)Fe(CO)2(THF)](BARF)] (3) solution. The 1H NMR spectrum (Supplementary Figure 6) of the in situ generated 3 in d8-THF reveals a diamagnetic complex that exhibits a thioether S(CH3) resonance at 2.80 ppm and 9,10-H resonances of the anthracene scaffold at 8.43, 8.55 ppm. A singlet peak at 7.70 ppm was assigned as an NH resonance by disappearance after H/D exchange in 1H NMR spectrum. Additionally, the presence of two Fe-carbonyl moieties (2025, 1970 cm-1) and a carbamoyl v(CO) group (1613 cm-1) supports conservation of the Fe coordination in 3, but the blue-shifted carbonyl features relative to 1 (2031 and 1981 cm–1) supports iodide abstraction (Supplementary Figure 7). DFT analysis of the THF-solvato species 3 compared with an authentically 5-coordinate species showed the 6-coordinate 3 to be significantly lower energy (17.3 kcal/mol, Table S2).
