190366-65-5Relevant academic research and scientific papers
Cooperative redox regulation of [4Fe-4S] ferredoxin model arenethiolate complexes by NH· · ·S hydrogen bonds and an aromatic C-H···S interaction
Ueno, Takafumi,Inohara, Masahiro,Ueyama, Norikazu,Nakamura, Akira
, p. 1077 - 1083 (2007/10/03)
A series of the model complexes containing ortho-substituted arenethiolato ligands, ((Et4N)2[Fe4S4(S-2- RCONHC6H4)4] {R=Ph (1), 4-MeO-C6H4 (2), and4-F-C6H4 (3)} and (Et4N)2[Fe 4S4{S-2,6-(RCONH)2C6H 3}4] {R=Ph (4), 4-MeO-C6H4 (5), and 4-F-C6H4 (6)}) was synthesized and characterized by 1NMR, IR spectroscopy, and cyclic voltammetry. The solution structures of these complexes are discussed based on their 1NMR T1 data and moleculardynamics calculations. Complex 4 has a shorter distance (av. 4.3 A) between the protons of the benzoyl group and the inorganic sulfur atom of the [4Fe-4S] cluster than the corresponding ones of 1 (av. 6.2 A). These results indicate the C-H · · · S interaction between the protons of the benzoyl group and the sulfur atom of the [4Fe-4S] cluster. The [Fe4S4(SAr)4] 2-/[Fe4S4(SAr)4]3- redox potential for 1 and 4 are-0.86 and-0.65 V, respectively. The difference between 1 and 4 is Δ0.21 V. This is larger than the value Δ0.11 V between [Fe4S4(S-2-t-BuCONHC6H4)4] 2- (-0.91 V) and [Fe4S4{S-2,6-(t-BuCONH) 2C6H3}4]2- (-0.80 V), considered to be the difference between singly and doubly NH· · ·S hydrogen-bonded complexes. The redox potentials for 1-6 follow the trend of the Hammett σ mvalues, showing that the aromatic ring of the benzoyl group interacts with the [4Fe-4S] cluster directly. A cooperative effect between the C-H· · ·S interaction and the NH ·· · S hydrogen bond is thus found to regulate the redox potential of the model complexes.
