Abstract
This paper discusses diiron complexes implicated as intermediates in the biosynthesis of the [2Fe](H) site of the [FeFe]-hydrogenases. These complexes include [Fe(2)(μ-SH)(μ-SR)(CN)(2)(CO)(4)](2-) (R = H, CH(2)NH(2) [2(H,R)](2-)), which are available from the new precursor [Fe(2)(μ-S(2))(CN)(2)(CO)(4)](2-) ([1](2-)). Complex [1](2-) was prepared by treating Fe(2)(μ-S(2))(CO)(6) with two equiv of KN(tms)(2). Access to [2(H,R)](2-) involves the reaction of [1](2-) with LiBHEt(3) followed by quenching with the equivalent of R(+). Similarly, access to [Fe(2)(μ-SMe)(μ-SCH(2)NHFmoc)(CN)(2)(CO)(4)](2-) ([2(Me,CH2NHFmoc)](2-)) involves treating [1](2-) with MeLi, followed by quenching with FmocNHCH(2)OAc. As established by (15)N-labeling, deprotection of [2(H,CH2NHFmoc)](2-) gave the azadithiolate [Fe(2)[(μ-SCH(2))(15)NH](CN)(2)(CO)(4)](2-) ([4(15)N](2-)) and (15)NH(3).