Unprecedented Stabilization of Cobalt(II) in a Tetrahedral S2O2 Environment: The Use of a Redox-Noninnocent Ligand
详细信息 查看全文
- 作者：Nú ; ria Duran ; William Clegg ; Lourdes Cucurull-Sá ; nchez ; Robert A. Coxall ; Hermas R. Jimé ; nez ; José ; -Marí ; a Moratal ; Francesc Lloret ; and Pilar Gonzá ; lez-Duarte
- 刊名：Inorganic Chemistry
- 出版年：2000
- 出版时间：October 16, 2000
- 年：2000
- 卷：39
- 期：21
- 页码：4821 - 4832
- 全文大小：189K
- 年卷期：v.39,no.21(October 16, 2000)
- ISSN：1520-510X
文摘
The reaction of Zn(II) and Co(II) with thiosalicylic acid, o-HSC6H4COOH, and its methyl ester has led to thefollowing complexes: [Zn(SC6H4COO)] (1), (NEt4)Na[Zn(SC6H4COO)2]·H2O (2), (NEt4)2Na[Co(SC6H4COO)3]·2H2O (3), (NEt4)3Na3[{Co(SC6H4COO)3}2]·6MeOH (4), [Zn(SC6H4COOMe)2] (5), and [Co(SC6H4COOMe)n], n= 2 (6), 3 (7). These ligands have not allowed stabilization of Co(II) in a sulfur-oxygen coordination environment.The structures of complexes 2-4 and 7 have been determined crystallographically. Those of 2-4 show significantsimilarities such as the behavior of the -SC6H4COO- anion as chelating ligand and the involvement of sodiumions as a structural element. Thus, the structure of the [Na{Zn(SC6H4COO)2}(H2O)]- anion in complex 2 can bedescribed as infinite chains of consecutive [Zn(SC6H4COO)2]2- metalloligands linked by [Na(H2O)]+ centers,that of the [Na{Co(SC6H4COO)3(H2O)2}]24- anion in 3 as a centrosymmetric tetranuclear Co2Na2 dimer with a{CoIII(S
O)3}Na(
-H2O)2Na{CoIII(SO)3} core, and that of the pentanuclear [Na3{Co(SC6H4COO)3}2(MeOH)6]3-anion in 4 as two dinuclear [{CoIII(SO)3}Na(MeOH)3] fragments linked to a central sodium ion, which appearsto be the first structurally characterized example of a NaS6 site. The use of the o-HSC6H4COOMe ligand allowedthe synthesis of [Co(SC6H4COOMe)2] (6) but not its full structural characterization. Instead, [Co(SC6H4COOMe)3](7) was obtained and structurally characterized. It consists of mononuclear molecules containing an octahedralCoIIIS3O3 core. The selection of 2,2-diphenyl-2-mercaptoacetic acid as ligand with reductive properties has affordedthe first mononuclear complex containing a CoIIS2O2 core and thus an unprecedented model for Co(II)-substitutedmetalloproteins containing tetrahedral MS2O2 active sites. The synthesis and full structural characterization ofthe isostructural complexes (NEt4)2[Zn{Ph2C(S)COO}2] (8) and (NEt4)2[Co{Ph2C(S)COO}2] (9) show that theyconsist of discrete [M{Ph2C(S)COO}2]2- anions, with a distorted tetrahedral coordination about the metal. Inaddition, the stability conferred by the ligand on the CoIIS2O2 core has allowed its characterization in solution byparamagnetic 1D and 2D 1H NMR studies. The longitudinal relaxation times of the hyperfine-shifted resonancesand NOESY spectra have led to the assignment of all resonances of the cobalt complex and confirmed that itmaintains its tetrahedral geometry in solution. Magnetic measurements (2-300 K) for complex 9 and 9·2H2O arein good agreement with distorted tetrahedral and octahedral environments, respectively.
O)3}Na(-H2O)2Na{CoIII(SO)3} core, and that of the pentanuclear [Na3{Co(SC6H4COO)3}2(MeOH)6]3-anion in 4 as two dinuclear [{CoIII(SO)3}Na(MeOH)3] fragments linked to a central sodium ion, which appearsto be the first structurally characterized example of a NaS6 site. The use of the o-HSC6H4COOMe ligand allowedthe synthesis of [Co(SC6H4COOMe)2] (6) but not its full structural characterization. Instead, [Co(SC6H4COOMe)3](7) was obtained and structurally characterized. It consists of mononuclear molecules containing an octahedralCoIIIS3O3 core. The selection of 2,2-diphenyl-2-mercaptoacetic acid as ligand with reductive properties has affordedthe first mononuclear complex containing a CoIIS2O2 core and thus an unprecedented model for Co(II)-substitutedmetalloproteins containing tetrahedral MS2O2 active sites. The synthesis and full structural characterization ofthe isostructural complexes (NEt4)2[Zn{Ph2C(S)COO}2] (8) and (NEt4)2[Co{Ph2C(S)COO}2] (9) show that theyconsist of discrete [M{Ph2C(S)COO}2]2- anions, with a distorted tetrahedral coordination about the metal. Inaddition, the stability conferred by the ligand on the CoIIS2O2 core has allowed its characterization in solution byparamagnetic 1D and 2D 1H NMR studies. The longitudinal relaxation times of the hyperfine-shifted resonancesand NOESY spectra have led to the assignment of all resonances of the cobalt complex and confirmed that itmaintains its tetrahedral geometry in solution. Magnetic measurements (2-300 K) for complex 9 and 9·2H2O arein good agreement with distorted tetrahedral and octahedral environments, respectively.