Protonolysis of platinum(II) and palladium(II) methyl complexes: A combined experimental and theoretical investigation

John E. Bercaw; George S. Chen; Jay A. Labinger; Bo Lin Lin

doi:10.1021/om100655w

Protonolysis of platinum(II) and palladium(II) methyl complexes: A combined experimental and theoretical investigation

John E. Bercaw, George S. Chen, Jay A. Labinger, Bo Lin Lin

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Abstract

The protonolysis of platinum(II) and palladium(II) methyl complexes has been investigated by both experiment and computation. Previously the protonolysis of (COD)Pt^II(CH₃)₂ by CF ₃COOY or (dppe)Pd^II(CH₃)₂ by CF ₃CY₂OY (Y = H, D) was found to be accompanied by abnormally large and highly temperature-dependent kinetic isotope effects (KIEs), suggesting the involvement of tunneling. Here we find normal KIEs and no evidence of tunneling for protonolysis of (tmeda)Pt^II(CH ₃)Cl by CF₃COOY (Y = H, D). Density functional theory (DFT) calculations indicate that protonation at the metal center followed by reductive coupling to the methane σ adduct (stepwise pathway) is favored for Pt complexes with good electron donor ligands, whereas direct protonation of the M-CH₃ bond to generate the methane σ adduct (concerted pathway) is favored for Pt with electron-withdrawing ligands as well as for Pd. We suggest that KIE behavior consistent with tunneling may be an experimental indicator of the concerted pathway.

Original language	English (US)
Pages (from-to)	4354-4359
Number of pages	6
Journal	Organometallics
Volume	29
Issue number	19
DOIs	https://doi.org/10.1021/om100655w
State	Published - Oct 11 2010
Externally published	Yes

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Organic Chemistry
Inorganic Chemistry

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title = "Protonolysis of platinum(II) and palladium(II) methyl complexes: A combined experimental and theoretical investigation",

abstract = "The protonolysis of platinum(II) and palladium(II) methyl complexes has been investigated by both experiment and computation. Previously the protonolysis of (COD)PtII(CH3)2 by CF 3COOY or (dppe)PdII(CH3)2 by CF 3CY2OY (Y = H, D) was found to be accompanied by abnormally large and highly temperature-dependent kinetic isotope effects (KIEs), suggesting the involvement of tunneling. Here we find normal KIEs and no evidence of tunneling for protonolysis of (tmeda)PtII(CH 3)Cl by CF3COOY (Y = H, D). Density functional theory (DFT) calculations indicate that protonation at the metal center followed by reductive coupling to the methane σ adduct (stepwise pathway) is favored for Pt complexes with good electron donor ligands, whereas direct protonation of the M-CH3 bond to generate the methane σ adduct (concerted pathway) is favored for Pt with electron-withdrawing ligands as well as for Pd. We suggest that KIE behavior consistent with tunneling may be an experimental indicator of the concerted pathway.",

author = "Bercaw, {John E.} and Chen, {George S.} and Labinger, {Jay A.} and Lin, {Bo Lin}",

year = "2010",

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doi = "10.1021/om100655w",

language = "English (US)",

volume = "29",

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journal = "Organometallics",

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publisher = "American Chemical Society",

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T1 - Protonolysis of platinum(II) and palladium(II) methyl complexes

T2 - A combined experimental and theoretical investigation

AU - Bercaw, John E.

AU - Chen, George S.

AU - Labinger, Jay A.

AU - Lin, Bo Lin

PY - 2010/10/11

Y1 - 2010/10/11

N2 - The protonolysis of platinum(II) and palladium(II) methyl complexes has been investigated by both experiment and computation. Previously the protonolysis of (COD)PtII(CH3)2 by CF 3COOY or (dppe)PdII(CH3)2 by CF 3CY2OY (Y = H, D) was found to be accompanied by abnormally large and highly temperature-dependent kinetic isotope effects (KIEs), suggesting the involvement of tunneling. Here we find normal KIEs and no evidence of tunneling for protonolysis of (tmeda)PtII(CH 3)Cl by CF3COOY (Y = H, D). Density functional theory (DFT) calculations indicate that protonation at the metal center followed by reductive coupling to the methane σ adduct (stepwise pathway) is favored for Pt complexes with good electron donor ligands, whereas direct protonation of the M-CH3 bond to generate the methane σ adduct (concerted pathway) is favored for Pt with electron-withdrawing ligands as well as for Pd. We suggest that KIE behavior consistent with tunneling may be an experimental indicator of the concerted pathway.

AB - The protonolysis of platinum(II) and palladium(II) methyl complexes has been investigated by both experiment and computation. Previously the protonolysis of (COD)PtII(CH3)2 by CF 3COOY or (dppe)PdII(CH3)2 by CF 3CY2OY (Y = H, D) was found to be accompanied by abnormally large and highly temperature-dependent kinetic isotope effects (KIEs), suggesting the involvement of tunneling. Here we find normal KIEs and no evidence of tunneling for protonolysis of (tmeda)PtII(CH 3)Cl by CF3COOY (Y = H, D). Density functional theory (DFT) calculations indicate that protonation at the metal center followed by reductive coupling to the methane σ adduct (stepwise pathway) is favored for Pt complexes with good electron donor ligands, whereas direct protonation of the M-CH3 bond to generate the methane σ adduct (concerted pathway) is favored for Pt with electron-withdrawing ligands as well as for Pd. We suggest that KIE behavior consistent with tunneling may be an experimental indicator of the concerted pathway.

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JO - Organometallics

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IS - 19

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Protonolysis of platinum(II) and palladium(II) methyl complexes: A combined experimental and theoretical investigation

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