Synthesis and characterization of heteroleptic iron(II) thiolate complexes with weak iron–arene interactions

Selective preparation and characterization of a series of heteroleptic thiolate complexes of iron(II) are described. The compounds were synthesized by treatment of iron bis-amide Fe{N(SiMe3)2}2 (1) with 1 equiv. of terphenyl thiols HS(2,6-(aryl)2C6H3) followed by addition of another equivalent of different thiol. An amide–thiolate intermediate [{(Me3Si)2N}Fe]2(μ-SDpp)2 (2; Dpp = 2,6-Ph2C6H3) was isolated from the 1:1 reaction of 1 and HSDpp. The X-ray crystal structures of all new thiolate complexes have been determined. The compounds crystallize as monomers or dimers, dependent on the substituents. They consist of distorted tetrahedral or trigonal-planar iron centers with weak interactions between the aromatic rings of thiolate ligands, where the Fe–C(arene) contact is 2.272(2) Å at shortest. The stronger iron–arene interaction appears to induce more pyramidalized geometry at the iron center.