Synthesis and characterization of diiron ethane-1,2-dithiolate complexes with tricyclohexylphosphine, methyl diphenylphosphinite, or tris(2-thienyl)phosphine coligands

Synthesis, Characterization and Electrochemical Studies of bis(Monothiolato) {FeFe} Complexes [Fe2(μ‐SC6H4‐OMe‐m)2(CO)5L] (L = CO, PCy3, PPh3)

“…FTIR spectra for complexes 1 – 3 were recorded in dichloromethane (Table 1; Figure S1, ESI). The ν CO wave numbers for the hexacarbonyl complex [Fe 2 (μ‐SC 6 H 4 ‐OMe‐ m ) 2 (CO) 6 ] 1 were higher than the monodentate phosphine substituted complexes 2 and 3 [55,78–96] . Electron density at the iron sites affects the stretching frequencies of the CO groups.…”

“…Also, reduction potentials of the three complexes appeared at less negative potentials than reported aliphatic dithiolate ligand‐based complexes [Fe 2 (μ‐edt)(CO) 5 (PCy 3 )] and [Fe 2 (μ‐edt)(CO) 5 (PPh 3 )] due to aromatic nature of 3‐methoxybenzenethiol in comparison to ethane‐1,2‐dithiol (Table 2). [80,82] CVs for complexes 1 – 3 were also measured at different scan rates (0.025–1.0 Vs −1 ). The peak current for the first reduction waves was linearly proportional to the square root of the scan rate suggesting that the redox processes were diffusion‐controlled (Figure S12, ESI) [103–105] …”

“…The ν CO wave numbers for the hexacarbonyl complex [Fe 2 (μ-SC 6 H 4 -OMe-m) 2 (CO) 6 ] 1 were higher than the monodentate phosphine substituted complexes 2 and 3. [55,[78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96] Electron density at the iron sites affects the stretching frequencies of the CO groups. In comparison to the phosphine substituted complexes, the hexacarbonyl complex has lower electron density at the iron centres.…”

“…Therefore, in continuation of this interest, the synthesis, spectroscopic characterization and electrochemical investigations of a series of monothiolate ligand‐based complexes [Fe 2 (μ‐SC 6 H 4 ‐OMe‐ m ) 2 (CO) 6 ] 1 , [Fe 2 (μ‐SC 6 H 4 ‐OMe‐ m ) 2 (CO) 5 (PCy 3 )] 2 and [Fe 2 (μ‐SC 6 H 4 ‐OMe‐ m ) 2 (CO) 5 (PPh 3 )] 3 are reported, where in ‐Saryl ligands substituted with electron‐donating ‐OMe groups form an integral part of the coordination sphere around the Fe centers. Further, the electrochemical properties of complexes 1 – 3 have been compared with o ‐ and p ‐OMe substituted monothiolate ligand‐based hexacarbonyl complexes and other previously reported analogous [FeFe] hydrogenase mimics incorporating aromatic dithiolates and PCy 3 / PPh 3 ligands [78–96] …”

“…Further, the electrochemical properties of complexes 1-3 have been compared with o-and p-OMe substituted monothiolate ligand-based hexacarbonyl complexes and other previously reported analogous [FeFe] hydrogenase mimics incorporating aromatic dithiolates and PCy 3 / PPh 3 ligands. [78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96]…”