Studies of Iron(III) Porphyrinates Containing Silanethiolate Ligands

The chemistry of several iron­(III) porphyrinates containing silanethiolate ligands is described. The complexes are prepared by protonolysis reactions of silanethiols with the iron­(III) precursors, [Fe­(OMe)­(TPP)] and [Fe­(OH)­(H₂O)­(TMP)] (TPP = dianion of <i>meso-</i>tetraphenylporphine; TMP = dianion of <i>meso-</i>tetramesitylporphine). Each of the compounds has been fully characterized in solution and the solid state. The stability of the silanethiolate complexes versus other iron­(III) porphyrinate complexes containing sulfur-based ligands allows for an examination of their reactivity with several biologically relevant small molecules including H₂S, NO, and 1-methylimidazole. Electrochemically, the silanethiolate complexes display a quasi-reversible one-electron oxidation event at potentials higher than that observed for an analogous arenethiolate complex. The behavior of these complexes versus other sulfur-ligated iron­(III) porphyrinates is discussed