TY - JOUR
T1 - Peracid oxidation of inorganic chalcogen ligands in transition metal complexes
AU - Hoots, John E.
AU - Lesch, David A.
AU - Rauchfuss, Thomas B.
PY - 1984/1
Y1 - 1984/1
N2 - The use of organic peracids as rapid, selective oxidation agents for coordinated chalcogens, η2-E2 (E = S, Se) and μ3-E (E = S, Se, Te), has been examined. Stepwise oxidation of [Ir(η2-S2)(dppe)2]PF6 with m-chloroperbenzoic acid (m-CPBA) yielded [Ir(η2-S2O)(dppe)2]PF6 (1) and [Ir(η2-S2O2)(dppe)2]PF 6 (2). Facile oxidation of [Ir(η2-Se2)(dppe)2]PF6 and Cp2Nb(η2-S2)Cl with peracetic acid produced [Ir(η2-Se2O)(dppe)2]PF6 (3) and Cp2Nb(η2-S2O)Cl (4). Similarly, reaction of Fe3(μ3-S)2(CO)9 and Fe2Pt(μ3-E)2(CO)6(PPh 3)2 (E = S, Se, Te) with m-CPBA produced the chalcogen monoxide complexes, Fe3(μ3-SO)(μ3-S)(CO)9 (5) and Fe2Pt(μ3-EO)(μ3-E)(CO) 6(PPh3)2 (6). The stereochemistry and reactivity of all of these complexes have been studied. Reaction of the η2-S2O complexes with nucleophiles (Nu = PPh3, CH3NC) revealed sulfur transfer as the favored reaction and the unsubstituted sulfur donor atom as the most reactive site. Attempted formation of η1- or η2-SO complexes by selective sulfur-abstraction reactions was unsuccessful, but an unsymmetrical dichalcogenide complex, [Ir(η2-SSe)(dppe)2]+ (7), was synthesized from [Ir(dppe)2]Cl and Cp2TiSxSe5-x (x ≈ 3). Examination of the oxygen-transfer capabilities of the iridium complexes revealed the following trend: Se2O ≫ S2O2 > S2O. In solution, the [Ir(Se2O)(dppe)2]PF6 complex spontaneously eliminates the exocyclic oxygen to yield [Ir(Se2)(dppe)2]+ and oxidizes C2H5SH to ethyl disulfide. In contrast, the [Ir(S2O)(dppe)2]Cl and Cp2Nb(S2O)Cl complexes show a pronounced tendency toward sulfur transfer to substrates but virtually no oxygen-transfer capability. The μ3-SO complexes proved to be virtually inert toward both O- and S-transfer reactions. Also described is the utility of chiral solvating and lanthanide shift reagents in the elucidation of the structure and stereochemistry of Cp2Nb(S2O)Cl using 1H NMR spectroscopy.
AB - The use of organic peracids as rapid, selective oxidation agents for coordinated chalcogens, η2-E2 (E = S, Se) and μ3-E (E = S, Se, Te), has been examined. Stepwise oxidation of [Ir(η2-S2)(dppe)2]PF6 with m-chloroperbenzoic acid (m-CPBA) yielded [Ir(η2-S2O)(dppe)2]PF6 (1) and [Ir(η2-S2O2)(dppe)2]PF 6 (2). Facile oxidation of [Ir(η2-Se2)(dppe)2]PF6 and Cp2Nb(η2-S2)Cl with peracetic acid produced [Ir(η2-Se2O)(dppe)2]PF6 (3) and Cp2Nb(η2-S2O)Cl (4). Similarly, reaction of Fe3(μ3-S)2(CO)9 and Fe2Pt(μ3-E)2(CO)6(PPh 3)2 (E = S, Se, Te) with m-CPBA produced the chalcogen monoxide complexes, Fe3(μ3-SO)(μ3-S)(CO)9 (5) and Fe2Pt(μ3-EO)(μ3-E)(CO) 6(PPh3)2 (6). The stereochemistry and reactivity of all of these complexes have been studied. Reaction of the η2-S2O complexes with nucleophiles (Nu = PPh3, CH3NC) revealed sulfur transfer as the favored reaction and the unsubstituted sulfur donor atom as the most reactive site. Attempted formation of η1- or η2-SO complexes by selective sulfur-abstraction reactions was unsuccessful, but an unsymmetrical dichalcogenide complex, [Ir(η2-SSe)(dppe)2]+ (7), was synthesized from [Ir(dppe)2]Cl and Cp2TiSxSe5-x (x ≈ 3). Examination of the oxygen-transfer capabilities of the iridium complexes revealed the following trend: Se2O ≫ S2O2 > S2O. In solution, the [Ir(Se2O)(dppe)2]PF6 complex spontaneously eliminates the exocyclic oxygen to yield [Ir(Se2)(dppe)2]+ and oxidizes C2H5SH to ethyl disulfide. In contrast, the [Ir(S2O)(dppe)2]Cl and Cp2Nb(S2O)Cl complexes show a pronounced tendency toward sulfur transfer to substrates but virtually no oxygen-transfer capability. The μ3-SO complexes proved to be virtually inert toward both O- and S-transfer reactions. Also described is the utility of chiral solvating and lanthanide shift reagents in the elucidation of the structure and stereochemistry of Cp2Nb(S2O)Cl using 1H NMR spectroscopy.
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U2 - 10.1021/ic00188a022
DO - 10.1021/ic00188a022
M3 - Article
AN - SCOPUS:0037629230
VL - 23
SP - 3130
EP - 3136
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 20
ER -