Heterodinuclear nickel(ii)-iron(ii) azadithiolates as structural and functional models for the active site of [NiFe]-hydrogenases.

To develop the biomimetic chemistry of [NiFe]-Hases, the first azadithiolato-bridged NiFe model complexes [CpNi{(μ-SCH)NR}Fe(CO)(diphos)]BF (5, R = Ph, diphos = dppv; 6, 4-ClCH, dppv; 7, 4-MeCH, dppv; 8, COCHPh, dppe; 9, H, dppe) have been synthesized well-designed synthetic routes. Thus, treatment of RN[CHS(O)CMe] with -BuONa followed by reaction of the resulting intermediates RN(CHSNa) with (dppv)Fe(CO)Cl or (dppe)Fe(CO)Cl gave the N-substituted azadithiolato-chelated Fe complexes [RN(CHS)]Fe(CO)(diphos) (1, R = Ph, diphos = dppv; 2, 4-ClCH, dppv; 3, 4-MeCH, dppv; 4, COCHPh, dppe). Further treatment of 1-4 with nickelocene in the presence of HBF·EtO afforded the corresponding N-substituted azadithiolato-bridged NiFe model complexes 5-8, while treatment of 8 with HBF·EtO resulted in formation of the parent azadithiolato-bridged model complex 9. While all the new complexes 1-9 were characterized by elemental analysis and spectroscopy, the molecular structures of model complexes 6-8 were confirmed by X-ray crystallographic study. In addition, model complexes 7 and 9 were found to be catalysts for H production with moderate / and overpotential values from TFA under CV conditions.