Iron(I)-Based Carbonyl Complexes with Bridging Thiolate Ligands as Light-Triggered CO Releasing Molecules (photoCORMs)

A series of thiolate ligands were used to synthesize diiron(I) hexacarbonyl bis(thiolates) for structural studies. Conversion of the corresponding thiols with triiron(0) dodecacarbonyl yields complexes of the type [{(CO)(3)Fe(mu-SR)}(2)] [R = C6H5 (1), C6H4-4-CH3 (2), C6H4-4-F (3), C6F5 (4), C6H4-4-CF3 (5), C6H2-2,4,6-(CH3)(3) (6), CH2-C6H4-4-Cl (7)]. These complexes were isolated and fully characterized, including X-ray crystal structures of complexes 2-7. The bridging thiolate ligands mainly influence the Fe-CO bond which is trans-positioned to the second iron(I) center. In solution, the anti-isomer with one axially and one equatorially oriented thiolate is the major species; severe steric strain induced by mesityl groups only allows the formation of syn-endo-isomeric molecules of 7. Furthermore, light-induced CO release at solid material at the three representative complexes 1, 3, and 6 verify suitability as photoCORMs.