Carbon monoxide release properties and molecular structures of phenylthiolatomanganese(i) carbonyl complexes of the type [(OC)4Mn(μ-S-aryl)]2

Abstract

Several phenylthiolatomanganese carbonyl complexes of the type [(OC)₄Mn(μ-SR)]₂ (R = Ph (1a), C₆H₄-4-CH₃ (1b), C₆H₄-4-CF₃ (1c), C₆H₄-4-F (1d), C₆H₄-4-Cl (1e), C₆H₄-4-OMe (1f), C₆F₅ (1g), and CH₂C₆H₄-4-Cl (1h)) have been prepared via the reaction of Mn₂(CO)₁₀ with diaryldisulfane or via the reaction of [(OC)₅MnBr] with arylthiols. These complexes lose two carbon monoxide molecules quite easily yielding tetranuclear [(OC)₃Mn(μ₃-SR)]₄ (2). Derivatives with fluoro-substituted aryl groups commonly form mixtures of dinuclear 1 and tetranuclear 2 which can quantitatively be converted to 2 by heating of the corresponding reaction mixtures. A unique trinuclear structure is found for the mesityl derivative [(OC)₄Mn(μ-SMes)]₃ (3) which is maintained in solution as verified by IR and NMR spectroscopy. Traces of an already known dinuclear by-product of the type [(OC)₃Mn(μ-SC₆H₃(-4-Me)-2-SC₆H₄-4-Me)]₂ (4) have been structurally characterized. The suitability of [(OC)₄Mn(μ-SPh)]₂ (1a) as a CO releasing molecule (CORM) for the administration of carbon monoxide has been studied. Two CO molecules are released upon dissolving in strongly Lewis basic solvents L, yielding [(OC)₃Mn(L)(μ-SPh)]₂, which liberates all the remaining CO molecules upon irradiation (photoCORM behavior).