Reactions of M2(CO)9L (M = Re, Mn; L = CO, MeCN) with thioacetamide and thiobenzamide: Facile metal-mediated nitrogen–hydrogen bond activation and subsequent carbon–nitrogen or sulfur–sulfur bond formation

• Coordination of thioacetamide and thiobenzamide to binuclear centre.
• Metal-mediated nitrogen–hydrogen bond activation.
• Carbon–nitrogen and sulfur–sulfur bond formation.

Addition of thioacetamide or thiobenzamide to Re2(CO)10 at room temperature in presence of Me3NO gives low yields of the simple substitution products Re2(CO)9{к1-SC(R)NH2} (1, R = Me; 2, R = Ph) in which the acyclic amides are bound through sulfur and occupy an equatorial site. In contrast, Me3NO initiated reactions of Mn2(CO)10 with the same amides lead to the isolation of hexacarbonyl complexes, Mn2(CO)6{μ-S2C(R)NH}2 (3, R = Me; 4, R = Ph), crystallographic studies revealing a binuclear core in which Mn(CO)3 moieties are spanned by two RC(SS)NH ligands. When Mn2(CO)9(NCMe) is used as the starting material only the mononuclear species Mn(CO)4{к1:η1-RC(S)NHCO} (5, R = Me; 6, R = Ph) could be isolated. These contain a chelating RC(S)NHCO ligand formed as a result of coupling the deprotonated amides with CO. Crystallographic studies have been carried out on both complexes, a careful inspection of bond lengths and angles within the chelate ring suggesting that a zwitterionic acyl-thiolate resonance structure is most prevalent.

Addition of thioacetamide or thiobenzamide to Re2(CO)9L gives the simple substitution products Re2(CO)9{к1-SC(R)NH2} in low yields. In contrast, reactions of Mn2(CO)10 with the same amides lead to dimeric Mn2(CO)6{μ-S2C(R)NH}2 and when Mn2(CO)9(NCMe) is used mononuclear complexes Mn(CO)4{к1:η1-RC(S)NHCO} are the sole products.Figure optionsDownload as PowerPoint slide