Part I. Novel mercaptoethoxy and mercaptoxylyleneoxy derivatives of meso-tetraphenylporphyrin, H\sb2TPP, and meso-tetranaphthalporphyrin, H\sb2TNP, with the potential for coordinating an iron-sulfur cubane cluster, have been synthesized and characterized. The thiol function is guarded during synthesis by an acetate protecting group, which is removed quantitatively by an acid-catalyzed hydrolysis reaction in the final workup step. The four "thiol-arms" on these light-sensitive porphyrins allows for the presence of atropisomers which have been observed and, in the case of the tetranaphthalporphyrin derivative, separated. The atropisomers of the acetylmercaptoxylyleneoxy derivatized tetraphenylporphyrin, H\sb2TAMXPP, interconvert at a rapid rate and are only observable by \sp1H NMR spectroscopy at $-70\sp\circC.Thefree−baseporphyrins,inthethiol−protectedform,areeasilymetallatedbyliteratureproceduresandthezinc(II)andiron(III)chloroderivativesofthesenewporphyrincompoundshavebeensynthesizedandcharacterized.PartII.Thethiolfunctionalityofthemercaptoxylyleneoxyderivativeoftetraphenylporphyrin,H\sb2TAMXPP,readilyexchangesforethanethiolwhenH\sb2TAMXPPisreactedwith(Fe\sb4S\sb4(SEt)\sb4\rbrack\sp{2-}.$ The dioxygen and light sensitive product, (cation)\sb2 (Fe\sb4S\sb4(H\sb2TMXPP)) has been isolated and characterized. Mossbauer and \sp1H NMR spectroscopy provide evidence for the successful synthesis of the desired porphyrin/iron-sulfur cluster compound. As such, this compound is the first example for the synthesis and isolation of a 1:1 porphyrin/iron-sulfur cluster compound and provides as a first generation model compound for the siroheme/iron-sulfur cluster structural unit found at the active site of sulfite reductase.