A Pentacoordinate Mn(II) Precatalyst That Exhibits Notable Aldehyde and Ketone Hydrosilylation Turnover Frequencies

Chandrani Ghosh, Tufan K. Mukhopadhyay, Marco Flores, Thomas L. Groy, Ryan Trovitch

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Heating (THF)2MnCl2 in the presence of the pyridine-substituted bis(imino)pyridine ligand, PyEtPDI, allowed preparation of the respective dihalide complex, (PyEtPDI)MnCl2. Reduction of this precursor using excess Na/Hg resulted in deprotonation of the chelate methyl groups to yield the bis(enamide)tris(pyridine)-supported product, (κ5-N,N,N,N,N-PyEtPDEA)Mn. This complex was characterized by single-crystal X-ray diffraction and found to possess an intermediate-spin (S = 3/2) Mn(II) center by the Evans method and electron paramagnetic resonance spectroscopy. Furthermore, (κ5-N,N,N,N,N-PyEtPDEA)Mn was determined to be an effective precatalyst for the hydrosilylation of aldehydes and ketones, exhibiting turnover frequencies of up to 2475 min-1 when employed under solvent-free conditions. This optimization allowed for isolation of the respective alcohols and, in two cases, the partially reacted silyl ethers, PhSiH(OR)2 [R = Cy and CH(Me)(nBu)]. The aldehyde hydrosilylation activity observed for (κ5-N,N,N,N,N-PyEtPDEA)Mn renders it one of the most efficient first-row transition metal catalysts for this transformation reported to date.

Original languageEnglish
Pages (from-to)10398-10406
Number of pages9
JournalInorganic Chemistry
Volume54
Issue number21
DOIs
Publication statusPublished - Oct 19 2015

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Hydrosilylation
Ketones
aldehydes
Aldehydes
ketones
pyridines
Deprotonation
Ethers
chelates
Transition metals
Paramagnetic resonance
ethers
isolation
electron paramagnetic resonance
alcohols
transition metals
Alcohols
Single crystals
Spectroscopy
methylidyne

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

Cite this

A Pentacoordinate Mn(II) Precatalyst That Exhibits Notable Aldehyde and Ketone Hydrosilylation Turnover Frequencies. / Ghosh, Chandrani; Mukhopadhyay, Tufan K.; Flores, Marco; Groy, Thomas L.; Trovitch, Ryan.

In: Inorganic Chemistry, Vol. 54, No. 21, 19.10.2015, p. 10398-10406.

Research output: Contribution to journalArticle

Ghosh, Chandrani ; Mukhopadhyay, Tufan K. ; Flores, Marco ; Groy, Thomas L. ; Trovitch, Ryan. / A Pentacoordinate Mn(II) Precatalyst That Exhibits Notable Aldehyde and Ketone Hydrosilylation Turnover Frequencies. In: Inorganic Chemistry. 2015 ; Vol. 54, No. 21. pp. 10398-10406.
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abstract = "Heating (THF)2MnCl2 in the presence of the pyridine-substituted bis(imino)pyridine ligand, PyEtPDI, allowed preparation of the respective dihalide complex, (PyEtPDI)MnCl2. Reduction of this precursor using excess Na/Hg resulted in deprotonation of the chelate methyl groups to yield the bis(enamide)tris(pyridine)-supported product, (κ5-N,N,N,N,N-PyEtPDEA)Mn. This complex was characterized by single-crystal X-ray diffraction and found to possess an intermediate-spin (S = 3/2) Mn(II) center by the Evans method and electron paramagnetic resonance spectroscopy. Furthermore, (κ5-N,N,N,N,N-PyEtPDEA)Mn was determined to be an effective precatalyst for the hydrosilylation of aldehydes and ketones, exhibiting turnover frequencies of up to 2475 min-1 when employed under solvent-free conditions. This optimization allowed for isolation of the respective alcohols and, in two cases, the partially reacted silyl ethers, PhSiH(OR)2 [R = Cy and CH(Me)(nBu)]. The aldehyde hydrosilylation activity observed for (κ5-N,N,N,N,N-PyEtPDEA)Mn renders it one of the most efficient first-row transition metal catalysts for this transformation reported to date.",
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AB - Heating (THF)2MnCl2 in the presence of the pyridine-substituted bis(imino)pyridine ligand, PyEtPDI, allowed preparation of the respective dihalide complex, (PyEtPDI)MnCl2. Reduction of this precursor using excess Na/Hg resulted in deprotonation of the chelate methyl groups to yield the bis(enamide)tris(pyridine)-supported product, (κ5-N,N,N,N,N-PyEtPDEA)Mn. This complex was characterized by single-crystal X-ray diffraction and found to possess an intermediate-spin (S = 3/2) Mn(II) center by the Evans method and electron paramagnetic resonance spectroscopy. Furthermore, (κ5-N,N,N,N,N-PyEtPDEA)Mn was determined to be an effective precatalyst for the hydrosilylation of aldehydes and ketones, exhibiting turnover frequencies of up to 2475 min-1 when employed under solvent-free conditions. This optimization allowed for isolation of the respective alcohols and, in two cases, the partially reacted silyl ethers, PhSiH(OR)2 [R = Cy and CH(Me)(nBu)]. The aldehyde hydrosilylation activity observed for (κ5-N,N,N,N,N-PyEtPDEA)Mn renders it one of the most efficient first-row transition metal catalysts for this transformation reported to date.

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