Redox chemistry of [CO4(CO)3(μ3-CO)3(μ3-C7H7)(η5-C7H9)] - Reversible carbon-carbon coupling versus metal cluster degradation

Hubert Wadepohl; Stefan Gebert; Hans Pritzkow; Domenico Osella; Carlo Nervi; Jan Fiedler

doi:10.1002/1099-0682(200008)2000:8<1833::aid-ejic1833>3.0.co;2-f

Redox chemistry of [CO₄(CO)₃(μ₃-CO)₃(μ₃-C₇H₇)(η⁵-C₇H₉)] - Reversible carbon-carbon coupling versus metal cluster degradation

Hubert Wadepohl, Stefan Gebert, Hans Pritzkow, Domenico Osella, Carlo Nervi, Jan Fiedler

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

Abstract

Chemical reduction of the tetracobalt cluster complex [C0₄(CO)₃(μ₃- CO)₃(μ₃-C₇H₇)(η⁵-C₇H₉)] (3), followed by addition of [PPh₄]Br, gives the complex [{C0₄(CO)₃(μ₃-CO)₃(μ₃-C₇H₇)}₂{μ-η⁴:η⁴- C₇H₉)₂}]^2- as a mixture of two diastereomers [4A]^2- and [4B]^2- in high yield. The crystal structure of [4A]²-[PPh₄]₂·1.5C₇H₈ has been determined and confirms the reductive coupling of two Co₄ cluster coordinated apical cycloheptadienyl rings to form a bridging bicycloheptyl- 3,5,3',5'-tetraene ligand. Reduction of 3 with Li[HBEt₃] and subsequent treatment with aqueous [NnBu₄]Cl results in the formation of [Co₄(CO)₃(μ₃-CO)₃(μ₃-C₇H₇)(C₇H₁₀)]^- [5]^-. Addition of [(η- C₆H₆)Ru(NCMe)₃][BF₄]₂ after the borohydride reduction gives [Ru(η- C₆H₆)Co₃(CO)₃(μ₃-CO)₃(μ₃-C₇H₇)] (6), a product derived from reductive Co₄ cluster degradation. A detailed electrochemical and spectro- electrochemical study of the redox behaviour of 3 and [4]²- has been carried out. The complex potential current response of 3 is rationalized in terms of the formation of the radical anion [3]^- as the primary intermediate, which may be reversibly reduced further to give the much more stable [3]^2- and then [3]^3-. Dimerization of [3]^- to give [4]^2- occurs by formation of a new carbon-carbon bond between the apical C₇H₉ ligands. The two redox- active moieties in [4]2- behave as independent, non-interacting redox centres. The oxidized form 4 is unstable and dissociates back to 3 almost quantitatively, thus completing a redox cycle characteristic of a 'molecular battery'. The homogeneous rate constant for dimerization has been evaluated as K(DIM) (2[3]^- →[4]^2-) = 0.30 ± 0.05 mM^-1S^-1.

Original language	English
Pages (from-to)	1833-1843
Number of pages	11
Journal	European Journal of Inorganic Chemistry
Issue number	8
DOIs	https://doi.org/10.1002/1099-0682(200008)2000:8<1833::aid-ejic1833>3.0.co;2-f
Publication status	Published - 2000
Externally published	Yes

Keywords

Carbocycles
Clusters
Cobalt
Electrochemistry
Facial ligands

Access to Document

10.1002/1099-0682(200008)2000:8<1833::aid-ejic1833>3.0.co;2-f

Cite this

@article{bdd5d93977db4ef8867363931669b7b2,

title = "Redox chemistry of [CO4(CO)3(μ3-CO)3(μ3-C7H7)(η5-C7H9)] - Reversible carbon-carbon coupling versus metal cluster degradation",

abstract = "Chemical reduction of the tetracobalt cluster complex [C04(CO)3(μ3- CO)3(μ3-C7H7)(η5-C7H9)] (3), followed by addition of [PPh4]Br, gives the complex [{C04(CO)3(μ3-CO)3(μ3-C7H7)}2{μ-η4:η4- C7H9)2}]2- as a mixture of two diastereomers [4A]2- and [4B]2- in high yield. The crystal structure of [4A]2-[PPh4]2·1.5C7H8 has been determined and confirms the reductive coupling of two Co4 cluster coordinated apical cycloheptadienyl rings to form a bridging bicycloheptyl- 3,5,3',5'-tetraene ligand. Reduction of 3 with Li[HBEt3] and subsequent treatment with aqueous [NnBu4]Cl results in the formation of [Co4(CO)3(μ3-CO)3(μ3-C7H7)(C7H10)]- [5]-. Addition of [(η- C6H6)Ru(NCMe)3][BF4]2 after the borohydride reduction gives [Ru(η- C6H6)Co3(CO)3(μ3-CO)3(μ3-C7H7)] (6), a product derived from reductive Co4 cluster degradation. A detailed electrochemical and spectro- electrochemical study of the redox behaviour of 3 and [4]2- has been carried out. The complex potential current response of 3 is rationalized in terms of the formation of the radical anion [3]- as the primary intermediate, which may be reversibly reduced further to give the much more stable [3]2- and then [3]3-. Dimerization of [3]- to give [4]2- occurs by formation of a new carbon-carbon bond between the apical C7H9 ligands. The two redox- active moieties in [4]2- behave as independent, non-interacting redox centres. The oxidized form 4 is unstable and dissociates back to 3 almost quantitatively, thus completing a redox cycle characteristic of a 'molecular battery'. The homogeneous rate constant for dimerization has been evaluated as K(DIM) (2[3]- →[4]2-) = 0.30 ± 0.05 mM-1S-1.",

keywords = "Carbocycles, Clusters, Cobalt, Electrochemistry, Facial ligands",

author = "Hubert Wadepohl and Stefan Gebert and Hans Pritzkow and Domenico Osella and Carlo Nervi and Jan Fiedler",

year = "2000",

doi = "10.1002/1099-0682(200008)2000:8<1833::aid-ejic1833>3.0.co;2-f",

language = "English",

pages = "1833--1843",

journal = "European Journal of Inorganic Chemistry",

issn = "1434-1948",

publisher = "Wiley-VCH Verlag",

number = "8",

}

TY - JOUR

T1 - Redox chemistry of [CO4(CO)3(μ3-CO)3(μ3-C7H7)(η5-C7H9)] - Reversible carbon-carbon coupling versus metal cluster degradation

AU - Wadepohl, Hubert

AU - Gebert, Stefan

AU - Pritzkow, Hans

AU - Osella, Domenico

AU - Nervi, Carlo

AU - Fiedler, Jan

PY - 2000

Y1 - 2000

N2 - Chemical reduction of the tetracobalt cluster complex [C04(CO)3(μ3- CO)3(μ3-C7H7)(η5-C7H9)] (3), followed by addition of [PPh4]Br, gives the complex [{C04(CO)3(μ3-CO)3(μ3-C7H7)}2{μ-η4:η4- C7H9)2}]2- as a mixture of two diastereomers [4A]2- and [4B]2- in high yield. The crystal structure of [4A]2-[PPh4]2·1.5C7H8 has been determined and confirms the reductive coupling of two Co4 cluster coordinated apical cycloheptadienyl rings to form a bridging bicycloheptyl- 3,5,3',5'-tetraene ligand. Reduction of 3 with Li[HBEt3] and subsequent treatment with aqueous [NnBu4]Cl results in the formation of [Co4(CO)3(μ3-CO)3(μ3-C7H7)(C7H10)]- [5]-. Addition of [(η- C6H6)Ru(NCMe)3][BF4]2 after the borohydride reduction gives [Ru(η- C6H6)Co3(CO)3(μ3-CO)3(μ3-C7H7)] (6), a product derived from reductive Co4 cluster degradation. A detailed electrochemical and spectro- electrochemical study of the redox behaviour of 3 and [4]2- has been carried out. The complex potential current response of 3 is rationalized in terms of the formation of the radical anion [3]- as the primary intermediate, which may be reversibly reduced further to give the much more stable [3]2- and then [3]3-. Dimerization of [3]- to give [4]2- occurs by formation of a new carbon-carbon bond between the apical C7H9 ligands. The two redox- active moieties in [4]2- behave as independent, non-interacting redox centres. The oxidized form 4 is unstable and dissociates back to 3 almost quantitatively, thus completing a redox cycle characteristic of a 'molecular battery'. The homogeneous rate constant for dimerization has been evaluated as K(DIM) (2[3]- →[4]2-) = 0.30 ± 0.05 mM-1S-1.

AB - Chemical reduction of the tetracobalt cluster complex [C04(CO)3(μ3- CO)3(μ3-C7H7)(η5-C7H9)] (3), followed by addition of [PPh4]Br, gives the complex [{C04(CO)3(μ3-CO)3(μ3-C7H7)}2{μ-η4:η4- C7H9)2}]2- as a mixture of two diastereomers [4A]2- and [4B]2- in high yield. The crystal structure of [4A]2-[PPh4]2·1.5C7H8 has been determined and confirms the reductive coupling of two Co4 cluster coordinated apical cycloheptadienyl rings to form a bridging bicycloheptyl- 3,5,3',5'-tetraene ligand. Reduction of 3 with Li[HBEt3] and subsequent treatment with aqueous [NnBu4]Cl results in the formation of [Co4(CO)3(μ3-CO)3(μ3-C7H7)(C7H10)]- [5]-. Addition of [(η- C6H6)Ru(NCMe)3][BF4]2 after the borohydride reduction gives [Ru(η- C6H6)Co3(CO)3(μ3-CO)3(μ3-C7H7)] (6), a product derived from reductive Co4 cluster degradation. A detailed electrochemical and spectro- electrochemical study of the redox behaviour of 3 and [4]2- has been carried out. The complex potential current response of 3 is rationalized in terms of the formation of the radical anion [3]- as the primary intermediate, which may be reversibly reduced further to give the much more stable [3]2- and then [3]3-. Dimerization of [3]- to give [4]2- occurs by formation of a new carbon-carbon bond between the apical C7H9 ligands. The two redox- active moieties in [4]2- behave as independent, non-interacting redox centres. The oxidized form 4 is unstable and dissociates back to 3 almost quantitatively, thus completing a redox cycle characteristic of a 'molecular battery'. The homogeneous rate constant for dimerization has been evaluated as K(DIM) (2[3]- →[4]2-) = 0.30 ± 0.05 mM-1S-1.

KW - Carbocycles

KW - Clusters

KW - Cobalt

KW - Electrochemistry

KW - Facial ligands

UR - http://www.scopus.com/inward/record.url?scp=0033853116&partnerID=8YFLogxK

U2 - 10.1002/1099-0682(200008)2000:8<1833::aid-ejic1833>3.0.co;2-f

DO - 10.1002/1099-0682(200008)2000:8<1833::aid-ejic1833>3.0.co;2-f

M3 - Article

SN - 1434-1948

SP - 1833

EP - 1843

JO - European Journal of Inorganic Chemistry

JF - European Journal of Inorganic Chemistry

IS - 8

ER -

Redox chemistry of [CO₄(CO)₃(μ₃-CO)₃(μ₃-C₇H₇)(η⁵-C₇H₉)] - Reversible carbon-carbon coupling versus metal cluster degradation

Abstract

Keywords

Access to Document

Other files and links

Fingerprint

Cite this