The Influence of OH Groups in [Fe(CO)3]2[(μ-ECH2)2C(CH2OH)2] (E = S, Se) Complexes toward the Cathodic Process

[FeFe] hydrogenase model complexes [Fe(CO)(3)](2)[(mu-ECH2)(2)C(CH2OH)(2)] (E = S (1) or Se (2)) containing CH2OH bridge-head substituents were synthesized via reaction of equimolar amounts of 4,4-bis(hydroxymethyl)-1,2-dithiolane (A) or 4,4-bis(hydroxymethyl)- 1,2-diselenolane (B) with Fe-3(CO)(12) in toluene at 100 degrees C. The presence of OH groups in complexes 1 and 2 is found to influence the cathodic processes and their potentials. The catalytic reduction of acetic acid (AcOH) occurs by the anions 1(-) and 2(-), while the neutral complexes are procatalysts.