Electrochemical Oxidation and Reduction of Cationic Carbonyl Hydride Complexes of Group VI Transition Metals

Frank Marken; Alan M. Bond; Ray Colton

doi:10.1021/ic00111a016

Electrochemical Oxidation and Reduction of Cationic Carbonyl Hydride Complexes of Group VI Transition Metals

Frank Marken, Alan M. Bond, Ray Colton

La Trobe University

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

Abstract

Voltammetric experiments are reported which establish kinetic and thermodynamic properties associated with the redox chemistry of carbonyl hydride complexes [M(CO)₂(P-P)₂H](SO₃CF₃) (M = Cr, Mo, W; P-P = Ph₂-PCH₂PPh₂ (dpm), Ph₂PCH₂CH₂PPh₂ (dpe)). A systematic relationship is shown between redox data obtained for the hydride complexes and those for the M(CO)₂(P-P)₂ complexes. Isomerization reactions of the seven-coordinate hydride complexes give rise to interesting mechanistic features which accompany the oxidation as well as the reduction, and both are found to proceed via metal-hydrogen bond cleavage. The oxidation process corresponds to an ECEC reaction pathway {(E) [Mo(CO)₂(dpe)₂H]+ = [Mo(CO)₂(dpe)₂H]²⁺ + e⁻; (C) [Mo(CO)₂(dpe)₂H]²⁺ ⇄ trans-[Mo(CO)₂(dpe)₂]⁺ + H+; (E) trans-[Mo(CO)₂(dpe)₂]⁺ ⇄ trans-[Mo(CO)₂(dpe)₂]²⁺ + e⁻; (C) trans-[Mo(CO)₂(dpe)₂]²⁺ → products} or a related mechanism while the reduction process involves the formation of hydrogen: [Mo(CO)₂(dpe)₂H]⁺ + e⁻ ⇄ cis-Mo(CO)₂(dpe)₂ + 1/2H₂. In the case of the oxidation of the tungsten and the the [Mo(CO)₂(dpe)₂H]⁺ complexes, a chemically reversible one-electron oxidation process is detected at low temperature in butyronitrile. The investigation of the deuterated complex [Mo(CO)₂(dpe)₂D]⁺ allows the detection of a normal isotope effect on the metal-hydrogen bond cleavage reaction. The oxidized species [M(CO)₂-(P-P)₂H]²⁺ can be viewed as extremely strong acids.

Original language	English
Pages (from-to)	1705-1710
Number of pages	6
Journal	Inorganic Chemistry
Volume	34
Issue number	7
DOIs	https://doi.org/10.1021/ic00111a016
Publication status	Published - 1 Mar 1995

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry

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@article{19464c812c9b4b44aff74de200d560a0,

title = "Electrochemical Oxidation and Reduction of Cationic Carbonyl Hydride Complexes of Group VI Transition Metals",

abstract = "Voltammetric experiments are reported which establish kinetic and thermodynamic properties associated with the redox chemistry of carbonyl hydride complexes [M(CO)2(P-P)2H](SO3CF3) (M = Cr, Mo, W; P-P = Ph2-PCH2PPh2 (dpm), Ph2PCH2CH2PPh2 (dpe)). A systematic relationship is shown between redox data obtained for the hydride complexes and those for the M(CO)2(P-P)2 complexes. Isomerization reactions of the seven-coordinate hydride complexes give rise to interesting mechanistic features which accompany the oxidation as well as the reduction, and both are found to proceed via metal-hydrogen bond cleavage. The oxidation process corresponds to an ECEC reaction pathway {(E) [Mo(CO)2(dpe)2H]+ = [Mo(CO)2(dpe)2H]2+ + e−; (C) [Mo(CO)2(dpe)2H]2+ ⇄ trans-[Mo(CO)2(dpe)2]+ + H+; (E) trans-[Mo(CO)2(dpe)2]+ ⇄ trans-[Mo(CO)2(dpe)2]2+ + e−; (C) trans-[Mo(CO)2(dpe)2]2+ → products} or a related mechanism while the reduction process involves the formation of hydrogen: [Mo(CO)2(dpe)2H]+ + e− ⇄ cis-Mo(CO)2(dpe)2 + 1/2H2. In the case of the oxidation of the tungsten and the the [Mo(CO)2(dpe)2H]+ complexes, a chemically reversible one-electron oxidation process is detected at low temperature in butyronitrile. The investigation of the deuterated complex [Mo(CO)2(dpe)2D]+ allows the detection of a normal isotope effect on the metal-hydrogen bond cleavage reaction. The oxidized species [M(CO)2-(P-P)2H]2+ can be viewed as extremely strong acids.",

author = "Frank Marken and Bond, {Alan M.} and Ray Colton",

year = "1995",

month = mar,

day = "1",

doi = "10.1021/ic00111a016",

language = "English",

volume = "34",

pages = "1705--1710",

journal = "Inorganic Chemistry",

issn = "0020-1669",

publisher = "American Chemical Society",

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TY - JOUR

T1 - Electrochemical Oxidation and Reduction of Cationic Carbonyl Hydride Complexes of Group VI Transition Metals

AU - Marken, Frank

AU - Bond, Alan M.

AU - Colton, Ray

PY - 1995/3/1

Y1 - 1995/3/1

N2 - Voltammetric experiments are reported which establish kinetic and thermodynamic properties associated with the redox chemistry of carbonyl hydride complexes [M(CO)2(P-P)2H](SO3CF3) (M = Cr, Mo, W; P-P = Ph2-PCH2PPh2 (dpm), Ph2PCH2CH2PPh2 (dpe)). A systematic relationship is shown between redox data obtained for the hydride complexes and those for the M(CO)2(P-P)2 complexes. Isomerization reactions of the seven-coordinate hydride complexes give rise to interesting mechanistic features which accompany the oxidation as well as the reduction, and both are found to proceed via metal-hydrogen bond cleavage. The oxidation process corresponds to an ECEC reaction pathway {(E) [Mo(CO)2(dpe)2H]+ = [Mo(CO)2(dpe)2H]2+ + e−; (C) [Mo(CO)2(dpe)2H]2+ ⇄ trans-[Mo(CO)2(dpe)2]+ + H+; (E) trans-[Mo(CO)2(dpe)2]+ ⇄ trans-[Mo(CO)2(dpe)2]2+ + e−; (C) trans-[Mo(CO)2(dpe)2]2+ → products} or a related mechanism while the reduction process involves the formation of hydrogen: [Mo(CO)2(dpe)2H]+ + e− ⇄ cis-Mo(CO)2(dpe)2 + 1/2H2. In the case of the oxidation of the tungsten and the the [Mo(CO)2(dpe)2H]+ complexes, a chemically reversible one-electron oxidation process is detected at low temperature in butyronitrile. The investigation of the deuterated complex [Mo(CO)2(dpe)2D]+ allows the detection of a normal isotope effect on the metal-hydrogen bond cleavage reaction. The oxidized species [M(CO)2-(P-P)2H]2+ can be viewed as extremely strong acids.

AB - Voltammetric experiments are reported which establish kinetic and thermodynamic properties associated with the redox chemistry of carbonyl hydride complexes [M(CO)2(P-P)2H](SO3CF3) (M = Cr, Mo, W; P-P = Ph2-PCH2PPh2 (dpm), Ph2PCH2CH2PPh2 (dpe)). A systematic relationship is shown between redox data obtained for the hydride complexes and those for the M(CO)2(P-P)2 complexes. Isomerization reactions of the seven-coordinate hydride complexes give rise to interesting mechanistic features which accompany the oxidation as well as the reduction, and both are found to proceed via metal-hydrogen bond cleavage. The oxidation process corresponds to an ECEC reaction pathway {(E) [Mo(CO)2(dpe)2H]+ = [Mo(CO)2(dpe)2H]2+ + e−; (C) [Mo(CO)2(dpe)2H]2+ ⇄ trans-[Mo(CO)2(dpe)2]+ + H+; (E) trans-[Mo(CO)2(dpe)2]+ ⇄ trans-[Mo(CO)2(dpe)2]2+ + e−; (C) trans-[Mo(CO)2(dpe)2]2+ → products} or a related mechanism while the reduction process involves the formation of hydrogen: [Mo(CO)2(dpe)2H]+ + e− ⇄ cis-Mo(CO)2(dpe)2 + 1/2H2. In the case of the oxidation of the tungsten and the the [Mo(CO)2(dpe)2H]+ complexes, a chemically reversible one-electron oxidation process is detected at low temperature in butyronitrile. The investigation of the deuterated complex [Mo(CO)2(dpe)2D]+ allows the detection of a normal isotope effect on the metal-hydrogen bond cleavage reaction. The oxidized species [M(CO)2-(P-P)2H]2+ can be viewed as extremely strong acids.

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U2 - 10.1021/ic00111a016

DO - 10.1021/ic00111a016

M3 - Article

AN - SCOPUS:0040519604

SN - 0020-1669

VL - 34

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JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 7

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Electrochemical Oxidation and Reduction of Cationic Carbonyl Hydride Complexes of Group VI Transition Metals

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