Hydrogen activation by biomimetic [NiFe]-hydrogenase model containing protected cyanide cofactors

Brian C. Manor; Thomas B. Rauchfuss

doi:10.1021/ja404580r

Hydrogen activation by biomimetic [NiFe]-hydrogenase model containing protected cyanide cofactors

Brian C. Manor
, Thomas B. Rauchfuss

Chemistry

Research output: Contribution to journal › Article › peer-review

Abstract

Described are experiments demonstrating incorporation of cyanide cofactors and hydride substrate into [NiFe]-hydrogenase (H₂ase) active site models. Complexes of the type (CO)₂(CN)₂Fe(pdt)Ni(dxpe) (dxpe = dppe, 1; dxpe = dcpe, 2) bind the Lewis acid B(C₆F ₅)₃ (BAr^F₃) to give the adducts (CO)₂(CNBAr^F₃)₂Fe(pdt)Ni(dxpe), (1(BAr^F₃)₂, 2(BAr^F₃) ₂). Upon decarbonylation using amine oxides, these adducts react with H₂ to give hydrido derivatives [(CO)(CNBAr^F ₃)₂Fe(H)(pdt)Ni(dxpe)]^- (dxpe = dppe, [H3(BAr^F₃)₂]^-; dxpe = dcpe, [H4(BAr^F₃)₂]^-). Crystallographic analysis shows that Et₄N[H3(BAr^F₃)₂] generally resembles the active site of the enzyme in the reduced, hydride-containing states (Ni-C/R). The Fe-H⋯Ni center is unsymmetrical with r_Fe-H = 1.51(3) Å and r_Ni-H = 1.71(3) Å. Both crystallographic and ¹⁹F NMR analyses show that the CNBAr ^F₃^- ligands occupy basal and apical sites. Unlike cationic Ni-Fe hydrides, [H3(BAr^F₃) ₂]^- and [H4(BAr^F₃)₂] ^- oxidize at mild potentials, near the Fc^+/0 couple. Electrochemical measurements indicate that in the presence of base, [H3(BAr ^F₃)₂]^- catalyzes the oxidation of H₂. NMR evidence indicates dihydrogen bonding between these anionic hydrides and R₃NH⁺ salts, which is relevant to the mechanism of hydrogenogenesis. In the case of Et₄N[H3(BAr ^F₃)₂], strong acids such as HCl induce H ₂ release to give the chloride Et₄N[(CO)(CNBAr ^F₃)₂Fe(Cl)(pdt)Ni(dppe)].

Original language	English (US)
Pages (from-to)	11895-11900
Number of pages	6
Journal	Journal of the American Chemical Society
Volume	135
Issue number	32
DOIs	https://doi.org/10.1021/ja404580r
State	Published - Aug 14 2013

ASJC Scopus subject areas

Catalysis
General Chemistry
Biochemistry
Colloid and Surface Chemistry

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@article{02e6134d9c704c38a619d8988eeb2dd2,

title = "Hydrogen activation by biomimetic [NiFe]-hydrogenase model containing protected cyanide cofactors",

abstract = "Described are experiments demonstrating incorporation of cyanide cofactors and hydride substrate into [NiFe]-hydrogenase (H2ase) active site models. Complexes of the type (CO)2(CN)2Fe(pdt)Ni(dxpe) (dxpe = dppe, 1; dxpe = dcpe, 2) bind the Lewis acid B(C6F 5)3 (BArF3) to give the adducts (CO)2(CNBArF3)2Fe(pdt)Ni(dxpe), (1(BArF3)2, 2(BArF3) 2). Upon decarbonylation using amine oxides, these adducts react with H2 to give hydrido derivatives [(CO)(CNBArF 3)2Fe(H)(pdt)Ni(dxpe)]- (dxpe = dppe, [H3(BArF3)2]-; dxpe = dcpe, [H4(BArF3)2]-). Crystallographic analysis shows that Et4N[H3(BArF3)2] generally resembles the active site of the enzyme in the reduced, hydride-containing states (Ni-C/R). The Fe-H⋯Ni center is unsymmetrical with rFe-H = 1.51(3) {\AA} and rNi-H = 1.71(3) {\AA}. Both crystallographic and 19F NMR analyses show that the CNBAr F3- ligands occupy basal and apical sites. Unlike cationic Ni-Fe hydrides, [H3(BArF3) 2]- and [H4(BArF3)2] - oxidize at mild potentials, near the Fc+/0 couple. Electrochemical measurements indicate that in the presence of base, [H3(BAr F3)2]- catalyzes the oxidation of H2. NMR evidence indicates dihydrogen bonding between these anionic hydrides and R3NH+ salts, which is relevant to the mechanism of hydrogenogenesis. In the case of Et4N[H3(BAr F3)2], strong acids such as HCl induce H 2 release to give the chloride Et4N[(CO)(CNBAr F3)2Fe(Cl)(pdt)Ni(dppe)].",

author = "Manor, \{Brian C.\} and Rauchfuss, \{Thomas B.\}",

year = "2013",

month = aug,

day = "14",

doi = "10.1021/ja404580r",

language = "English (US)",

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pages = "11895--11900",

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T1 - Hydrogen activation by biomimetic [NiFe]-hydrogenase model containing protected cyanide cofactors

AU - Manor, Brian C.

AU - Rauchfuss, Thomas B.

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N2 - Described are experiments demonstrating incorporation of cyanide cofactors and hydride substrate into [NiFe]-hydrogenase (H2ase) active site models. Complexes of the type (CO)2(CN)2Fe(pdt)Ni(dxpe) (dxpe = dppe, 1; dxpe = dcpe, 2) bind the Lewis acid B(C6F 5)3 (BArF3) to give the adducts (CO)2(CNBArF3)2Fe(pdt)Ni(dxpe), (1(BArF3)2, 2(BArF3) 2). Upon decarbonylation using amine oxides, these adducts react with H2 to give hydrido derivatives [(CO)(CNBArF 3)2Fe(H)(pdt)Ni(dxpe)]- (dxpe = dppe, [H3(BArF3)2]-; dxpe = dcpe, [H4(BArF3)2]-). Crystallographic analysis shows that Et4N[H3(BArF3)2] generally resembles the active site of the enzyme in the reduced, hydride-containing states (Ni-C/R). The Fe-H⋯Ni center is unsymmetrical with rFe-H = 1.51(3) Å and rNi-H = 1.71(3) Å. Both crystallographic and 19F NMR analyses show that the CNBAr F3- ligands occupy basal and apical sites. Unlike cationic Ni-Fe hydrides, [H3(BArF3) 2]- and [H4(BArF3)2] - oxidize at mild potentials, near the Fc+/0 couple. Electrochemical measurements indicate that in the presence of base, [H3(BAr F3)2]- catalyzes the oxidation of H2. NMR evidence indicates dihydrogen bonding between these anionic hydrides and R3NH+ salts, which is relevant to the mechanism of hydrogenogenesis. In the case of Et4N[H3(BAr F3)2], strong acids such as HCl induce H 2 release to give the chloride Et4N[(CO)(CNBAr F3)2Fe(Cl)(pdt)Ni(dppe)].

AB - Described are experiments demonstrating incorporation of cyanide cofactors and hydride substrate into [NiFe]-hydrogenase (H2ase) active site models. Complexes of the type (CO)2(CN)2Fe(pdt)Ni(dxpe) (dxpe = dppe, 1; dxpe = dcpe, 2) bind the Lewis acid B(C6F 5)3 (BArF3) to give the adducts (CO)2(CNBArF3)2Fe(pdt)Ni(dxpe), (1(BArF3)2, 2(BArF3) 2). Upon decarbonylation using amine oxides, these adducts react with H2 to give hydrido derivatives [(CO)(CNBArF 3)2Fe(H)(pdt)Ni(dxpe)]- (dxpe = dppe, [H3(BArF3)2]-; dxpe = dcpe, [H4(BArF3)2]-). Crystallographic analysis shows that Et4N[H3(BArF3)2] generally resembles the active site of the enzyme in the reduced, hydride-containing states (Ni-C/R). The Fe-H⋯Ni center is unsymmetrical with rFe-H = 1.51(3) Å and rNi-H = 1.71(3) Å. Both crystallographic and 19F NMR analyses show that the CNBAr F3- ligands occupy basal and apical sites. Unlike cationic Ni-Fe hydrides, [H3(BArF3) 2]- and [H4(BArF3)2] - oxidize at mild potentials, near the Fc+/0 couple. Electrochemical measurements indicate that in the presence of base, [H3(BAr F3)2]- catalyzes the oxidation of H2. NMR evidence indicates dihydrogen bonding between these anionic hydrides and R3NH+ salts, which is relevant to the mechanism of hydrogenogenesis. In the case of Et4N[H3(BAr F3)2], strong acids such as HCl induce H 2 release to give the chloride Et4N[(CO)(CNBAr F3)2Fe(Cl)(pdt)Ni(dppe)].

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UR - https://www.scopus.com/pages/publications/84882273532#tab=citedBy

U2 - 10.1021/ja404580r

DO - 10.1021/ja404580r

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AN - SCOPUS:84882273532

SN - 0002-7863

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JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 32

ER -

Hydrogen activation by biomimetic [NiFe]-hydrogenase model containing protected cyanide cofactors

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