Formation of iron thiolates via complexes of molecular hydrogen

Protonation of FeH2(DMPE)2 [DMPE = 1,2-bis(dimethylphosphino)ethane] by arene- or alkanethiols affords the molecular hydrogen complex [Fe(H2)H(DMPE)2]+, in which the weakly bound η2-coordinated H2 is readily displaced by alkane- and arenethiolates to give FeH(RS)(DMPE)2 and Fe(RS)2(DMPE)2. Both the thiolate iron hydrides and the iron dithiolates exist as equilibrating mixtures of cis and trans stereoisomers in solution, and both readily exchange thiol ligands with added thiols. Crystals of [FeSCH2CH2S(DMPE)2] are orthorhombic, of space group Pcan, with a = 10.309 (2) Å, b = 13.897 (2) Å, c = 15.090 (4) Å, Z = 4, and R = 0.052 (4728 F). The Fe-S bond length is 2.349 (1) Å.