Six-coordinate and five-coordinate FeII(CN)2(CO)x thiolate complexes (x = 1, 2): Synthetic advances for iron sites of [NiFe] hydrogenases

Wen Feng Liaw, Jiun Hung Lee, Hung Bin Gau, Chien Hong Chen, Shiou Ju Jung, Chen Hsiung Hung, Wen Yuan Chen, Ching-Han Hu, Gene Hsiang Lee

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Abstract

The dicyanodicarbonyliron(II) thiolate complexes trans, cis-[(CN)2(CO)2Fe(S,S-C-R)]- (R = OEt (2), N(Et)2 (3)) were prepared by the reaction of [Na][S-C(S)-R] and [Fe(CN)2(CO)3(Br)]- (1). Complex 1 was obtained from oxidative addition of cyanogen bromide to [Fe(CN)(CO)4]-. In a similar fashion, reaction of complex 1 with [Na][S,O-C5H4N], and [Na][S,N-C5H4] produced the six-coordinate trans,cis-[(CN)2-(CO)2Fe (S,O-C5H4N)]- (6) and trans,cis-[(CN)2 (CO)2Fe(S,N-C5H4)]- (7) individually. Photolysis of tetrahydrofuran (THF) solution of complexes 2, 3, and 7 under CO led to formation of the coordinatively unsaturated iron(II) dicyanocarbonyl thiolate compounds [(CN)2(CO)Fe(S,S-C-R)]- (R = OEt (4), N(Et)2 (5)) and [(CN)2(CO)Fe(S,N-C5H4)]- (8), respectively. The IR νCN stretching frequencies and patterns of complexes 4, 5, and 8 have unambiguously identified two CN- ligands occupying cis positions. In addition, density functional theory calculations suggest that the architecture of five-coordinate complexes 4, 5, and 8 with a vacant site trans to the CO ligand and two CN- ligands occupying cis positions serves as a conformational preference. Complexes 2, 3, and 7 were reobtained when the THF solution of complexes 4, 5, and 8 were exposed to CO atmosphere at 25 °C individually. Obviously, CO ligand can be reversibly bound to the FeII site in these model compounds. Isotopic shift experiments demonstrated the lability of carbonyl ligands of complexes 2, 3, 4, 5, 7, and 8. Complexes [(CN)2(CO)Fe(S,S-C-R)]- and NiA/NiC states [NiFe] hydrogenases from D. gigas exhibit a similar one-band pattern in the νCO region and two-band pattern in the νCN region individually, but in different positions, which may be accounted for by the distinct electronic effects betwen [S,S-C-R]- and cysteine ligands. Also, the facile formations of five-coordinate complexes 4, 5, and 8 imply that the strong σ-donor, weak π-acceptor CN- ligands play a key role in creating/stabilizing five-coordinate iron(II) [(CN)2(CO)Fe(S,S-C-R)]- complexes with a vacant coordination site trans to the CO ligand.

Original languageEnglish
Pages (from-to)1680-1688
Number of pages9
JournalJournal of the American Chemical Society
Volume124
Issue number8
DOIs
Publication statusPublished - 2002 Feb 27

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Carbon Monoxide
Iron
Ligands
nickel-iron hydrogenase
Photolysis
Stretching
Density functional theory
Cyanogen Bromide
Atmosphere
Cysteine

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Liaw, Wen Feng ; Lee, Jiun Hung ; Gau, Hung Bin ; Chen, Chien Hong ; Jung, Shiou Ju ; Hung, Chen Hsiung ; Chen, Wen Yuan ; Hu, Ching-Han ; Lee, Gene Hsiang. / Six-coordinate and five-coordinate FeII(CN)2(CO)x thiolate complexes (x = 1, 2) : Synthetic advances for iron sites of [NiFe] hydrogenases. In: Journal of the American Chemical Society. 2002 ; Vol. 124, No. 8. pp. 1680-1688.
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abstract = "The dicyanodicarbonyliron(II) thiolate complexes trans, cis-[(CN)2(CO)2Fe(S,S-C-R)]- (R = OEt (2), N(Et)2 (3)) were prepared by the reaction of [Na][S-C(S)-R] and [Fe(CN)2(CO)3(Br)]- (1). Complex 1 was obtained from oxidative addition of cyanogen bromide to [Fe(CN)(CO)4]-. In a similar fashion, reaction of complex 1 with [Na][S,O-C5H4N], and [Na][S,N-C5H4] produced the six-coordinate trans,cis-[(CN)2-(CO)2Fe (S,O-C5H4N)]- (6) and trans,cis-[(CN)2 (CO)2Fe(S,N-C5H4)]- (7) individually. Photolysis of tetrahydrofuran (THF) solution of complexes 2, 3, and 7 under CO led to formation of the coordinatively unsaturated iron(II) dicyanocarbonyl thiolate compounds [(CN)2(CO)Fe(S,S-C-R)]- (R = OEt (4), N(Et)2 (5)) and [(CN)2(CO)Fe(S,N-C5H4)]- (8), respectively. The IR νCN stretching frequencies and patterns of complexes 4, 5, and 8 have unambiguously identified two CN- ligands occupying cis positions. In addition, density functional theory calculations suggest that the architecture of five-coordinate complexes 4, 5, and 8 with a vacant site trans to the CO ligand and two CN- ligands occupying cis positions serves as a conformational preference. Complexes 2, 3, and 7 were reobtained when the THF solution of complexes 4, 5, and 8 were exposed to CO atmosphere at 25 °C individually. Obviously, CO ligand can be reversibly bound to the FeII site in these model compounds. Isotopic shift experiments demonstrated the lability of carbonyl ligands of complexes 2, 3, 4, 5, 7, and 8. Complexes [(CN)2(CO)Fe(S,S-C-R)]- and NiA/NiC states [NiFe] hydrogenases from D. gigas exhibit a similar one-band pattern in the νCO region and two-band pattern in the νCN region individually, but in different positions, which may be accounted for by the distinct electronic effects betwen [S,S-C-R]- and cysteine ligands. Also, the facile formations of five-coordinate complexes 4, 5, and 8 imply that the strong σ-donor, weak π-acceptor CN- ligands play a key role in creating/stabilizing five-coordinate iron(II) [(CN)2(CO)Fe(S,S-C-R)]- complexes with a vacant coordination site trans to the CO ligand.",
author = "Liaw, {Wen Feng} and Lee, {Jiun Hung} and Gau, {Hung Bin} and Chen, {Chien Hong} and Jung, {Shiou Ju} and Hung, {Chen Hsiung} and Chen, {Wen Yuan} and Ching-Han Hu and Lee, {Gene Hsiang}",
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Six-coordinate and five-coordinate FeII(CN)2(CO)x thiolate complexes (x = 1, 2) : Synthetic advances for iron sites of [NiFe] hydrogenases. / Liaw, Wen Feng; Lee, Jiun Hung; Gau, Hung Bin; Chen, Chien Hong; Jung, Shiou Ju; Hung, Chen Hsiung; Chen, Wen Yuan; Hu, Ching-Han; Lee, Gene Hsiang.

In: Journal of the American Chemical Society, Vol. 124, No. 8, 27.02.2002, p. 1680-1688.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Six-coordinate and five-coordinate FeII(CN)2(CO)x thiolate complexes (x = 1, 2)

T2 - Synthetic advances for iron sites of [NiFe] hydrogenases

AU - Liaw, Wen Feng

AU - Lee, Jiun Hung

AU - Gau, Hung Bin

AU - Chen, Chien Hong

AU - Jung, Shiou Ju

AU - Hung, Chen Hsiung

AU - Chen, Wen Yuan

AU - Hu, Ching-Han

AU - Lee, Gene Hsiang

PY - 2002/2/27

Y1 - 2002/2/27

N2 - The dicyanodicarbonyliron(II) thiolate complexes trans, cis-[(CN)2(CO)2Fe(S,S-C-R)]- (R = OEt (2), N(Et)2 (3)) were prepared by the reaction of [Na][S-C(S)-R] and [Fe(CN)2(CO)3(Br)]- (1). Complex 1 was obtained from oxidative addition of cyanogen bromide to [Fe(CN)(CO)4]-. In a similar fashion, reaction of complex 1 with [Na][S,O-C5H4N], and [Na][S,N-C5H4] produced the six-coordinate trans,cis-[(CN)2-(CO)2Fe (S,O-C5H4N)]- (6) and trans,cis-[(CN)2 (CO)2Fe(S,N-C5H4)]- (7) individually. Photolysis of tetrahydrofuran (THF) solution of complexes 2, 3, and 7 under CO led to formation of the coordinatively unsaturated iron(II) dicyanocarbonyl thiolate compounds [(CN)2(CO)Fe(S,S-C-R)]- (R = OEt (4), N(Et)2 (5)) and [(CN)2(CO)Fe(S,N-C5H4)]- (8), respectively. The IR νCN stretching frequencies and patterns of complexes 4, 5, and 8 have unambiguously identified two CN- ligands occupying cis positions. In addition, density functional theory calculations suggest that the architecture of five-coordinate complexes 4, 5, and 8 with a vacant site trans to the CO ligand and two CN- ligands occupying cis positions serves as a conformational preference. Complexes 2, 3, and 7 were reobtained when the THF solution of complexes 4, 5, and 8 were exposed to CO atmosphere at 25 °C individually. Obviously, CO ligand can be reversibly bound to the FeII site in these model compounds. Isotopic shift experiments demonstrated the lability of carbonyl ligands of complexes 2, 3, 4, 5, 7, and 8. Complexes [(CN)2(CO)Fe(S,S-C-R)]- and NiA/NiC states [NiFe] hydrogenases from D. gigas exhibit a similar one-band pattern in the νCO region and two-band pattern in the νCN region individually, but in different positions, which may be accounted for by the distinct electronic effects betwen [S,S-C-R]- and cysteine ligands. Also, the facile formations of five-coordinate complexes 4, 5, and 8 imply that the strong σ-donor, weak π-acceptor CN- ligands play a key role in creating/stabilizing five-coordinate iron(II) [(CN)2(CO)Fe(S,S-C-R)]- complexes with a vacant coordination site trans to the CO ligand.

AB - The dicyanodicarbonyliron(II) thiolate complexes trans, cis-[(CN)2(CO)2Fe(S,S-C-R)]- (R = OEt (2), N(Et)2 (3)) were prepared by the reaction of [Na][S-C(S)-R] and [Fe(CN)2(CO)3(Br)]- (1). Complex 1 was obtained from oxidative addition of cyanogen bromide to [Fe(CN)(CO)4]-. In a similar fashion, reaction of complex 1 with [Na][S,O-C5H4N], and [Na][S,N-C5H4] produced the six-coordinate trans,cis-[(CN)2-(CO)2Fe (S,O-C5H4N)]- (6) and trans,cis-[(CN)2 (CO)2Fe(S,N-C5H4)]- (7) individually. Photolysis of tetrahydrofuran (THF) solution of complexes 2, 3, and 7 under CO led to formation of the coordinatively unsaturated iron(II) dicyanocarbonyl thiolate compounds [(CN)2(CO)Fe(S,S-C-R)]- (R = OEt (4), N(Et)2 (5)) and [(CN)2(CO)Fe(S,N-C5H4)]- (8), respectively. The IR νCN stretching frequencies and patterns of complexes 4, 5, and 8 have unambiguously identified two CN- ligands occupying cis positions. In addition, density functional theory calculations suggest that the architecture of five-coordinate complexes 4, 5, and 8 with a vacant site trans to the CO ligand and two CN- ligands occupying cis positions serves as a conformational preference. Complexes 2, 3, and 7 were reobtained when the THF solution of complexes 4, 5, and 8 were exposed to CO atmosphere at 25 °C individually. Obviously, CO ligand can be reversibly bound to the FeII site in these model compounds. Isotopic shift experiments demonstrated the lability of carbonyl ligands of complexes 2, 3, 4, 5, 7, and 8. Complexes [(CN)2(CO)Fe(S,S-C-R)]- and NiA/NiC states [NiFe] hydrogenases from D. gigas exhibit a similar one-band pattern in the νCO region and two-band pattern in the νCN region individually, but in different positions, which may be accounted for by the distinct electronic effects betwen [S,S-C-R]- and cysteine ligands. Also, the facile formations of five-coordinate complexes 4, 5, and 8 imply that the strong σ-donor, weak π-acceptor CN- ligands play a key role in creating/stabilizing five-coordinate iron(II) [(CN)2(CO)Fe(S,S-C-R)]- complexes with a vacant coordination site trans to the CO ligand.

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