Transition Metal Complexes with Sulfur Ligands. 117.1 A Reaction Cycle for Nickel Mediated Thioester Formation from Alkyl, CO, and Thiolate Groups Modeling the Acetyl-Coenzyme A Synthase Fu
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- 作者：Dieter Sellmann ; Daniel Hä ; ussinger ; Falk Knoch ; and Matthias Moll
- 刊名：Journal of the American Chemical Society
- 出版年：1996
- 出版时间：June 12, 1996
- 年：1996
- 卷：118
- 期：23
- 页码：5368 - 5374
- 全文大小：304K
- 年卷期：v.118,no.23(June 12, 1996)
- ISSN：1520-5126
文摘
In quest of nickel complexes with sulfur ligation that model theacetyl-CoA synthase function of COdehydrogenase (CODH),[Ni('S4C3Me2')](1,'S4C3Me2'2-=1,3-bis(2-mercaptophenylthio)-2,2-dimethyl-propane(2-)) was synthesized by template alkylation ofNa2[Ni('S2')2]('S2'2- = benzene-1,2-dithiolate(2-))withCMe2(CH2Br)2. Acidichydrolysis of 1 yielded the thiol"S4C3Me2"-H2(2). Reduction of 1 with Na/Hg resultedincleavage of the'S4C3Me2'2-ligand and formation of the thermally stable trinuclear nickel(II)alkyl thiolato complex[Ni('
-S2C3Me2')]3(3,'S2C3Me2' 2-= 1-(2-mercaptophenylthio)-2,2-dimethylpropyl(2-)).Treatment of 3 with L= Py, THF, or PMe3 afforded the mononuclear compounds[Ni('S2C3Me2')(L)](4, L = Py; 5, L = PMe3).Thestoichiometric reaction of[Ni('S2C3Me2')(L)] with CO ledto the cyclic thioester'S2C3Me2CO'(6,'S2C3Me2CO'= 2,3-benzo-6,6-dimethyl-8-oxo-1,4-dithia-cyclooctane) andNi(CO)4. In the analogous reaction of5 with CO theintermediate nickel(II) acyl thiolato complex[Ni('S2C3Me2CO')(PMe3)](7,'S2C3Me2CO'(2-) =1-(2-mercaptophenylthio)-2,2-dimethyl-3-oxobutyl(2-)) could be intercepted and fullycharacterized. The reaction of Ni(CO)4 withthethiol 2 yielded the starting Ni(II) complex1 and allowed to close the reaction cycle that comprises theCODHsequence: [Ni] 
[Ni-alkyl] [Ni-acyl] [Ni] +thioester. The net reaction can be formulated as'S4C3Me2'-H2(2) + CO 'S2C3Me2CO'(6) + 'S2'-H2 and represents thefirst example of nickel mediated thioester formation ina complete reaction cycle. X-ray structure determinations ofcomplexes 1, 3, 4, and 7revealed approximately squareplanar coordination geometry for all Ni centers.
-S2C3Me2')]3(3,'S2C3Me2' 2-= 1-(2-mercaptophenylthio)-2,2-dimethylpropyl(2-)).Treatment of 3 with L= Py, THF, or PMe3 afforded the mononuclear compounds[Ni('S2C3Me2')(L)](4, L = Py; 5, L = PMe3).Thestoichiometric reaction of[Ni('S2C3Me2')(L)] with CO ledto the cyclic thioester'S2C3Me2CO'(6,'S2C3Me2CO'= 2,3-benzo-6,6-dimethyl-8-oxo-1,4-dithia-cyclooctane) andNi(CO)4. In the analogous reaction of5 with CO theintermediate nickel(II) acyl thiolato complex[Ni('S2C3Me2CO')(PMe3)](7,'S2C3Me2CO'(2-) =1-(2-mercaptophenylthio)-2,2-dimethyl-3-oxobutyl(2-)) could be intercepted and fullycharacterized. The reaction of Ni(CO)4 withthethiol 2 yielded the starting Ni(II) complex1 and allowed to close the reaction cycle that comprises theCODHsequence: [Ni] [Ni-alkyl] [Ni-acyl] [Ni] +thioester. The net reaction can be formulated as'S4C3Me2'-H2(2) + CO 'S2C3Me2CO'(6) + 'S2'-H2 and represents thefirst example of nickel mediated thioester formation ina complete reaction cycle. X-ray structure determinations ofcomplexes 1, 3, 4, and 7revealed approximately squareplanar coordination geometry for all Ni centers.