Isolation of a bis(imino)pyridine molybdenum(i) iodide complex through controlled reduction and interconversion of its reaction products

Raja Pal, Brian R. Cherry, Marco Flores, Thomas L. Groy, Ryan Trovitch

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Analysis of previously reported [(Ph2PPrPDI)MoI][I] by cyclic voltammetry revealed a reversible wave at -1.20 V vs. Fc+/0, corresponding to the Mo(ii)/Mo(i) redox couple. Reduction of [(Ph2PPrPDI)MoI][I] using stoichiometric K/naphthalene resulted in ligand deprotonation rather than reduction to yield a Mo(ii) monoiodide complex featuring a Mo-C bond to the α-position of one imine substituent, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI. Successful isolation of the inner-sphere Mo(i) monoiodide complex, (Ph2PPrPDI)MoI, was achieved via reduction of [(Ph2PPrPDI)MoI][I] with equimolar Na/naphthalene. This complex was found to have a near octahedral coordination geometry by single crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy revealed an unpaired Mo-based electron which is highly delocalized onto the PDI chelate core. Attempts to prepare a Mo(i) monohydride complex upon adding NaEt3BH to (Ph2PPrPDI)MoI resulted in disproportionation to yield an equimolar quantity of (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH and newly identified (Ph2PPrPDI)MoH2. Independent preparation of (Ph2PPrPDI)MoH2 was achieved by adding 2 equiv. NaEt3BH to [(Ph2PPrPDI)MoI][I] and a minimum hydride resonance T1 of 176 ms suggests that the Mo-bound H atoms are best described as classical hydrides. Interestingly, (Ph2PPrPDI)MoH2 can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI upon iodomethane addition, while (Ph2PPrPDI)MoH2 is prepared from (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI in the presence of excess NaEt3BH. Similarly, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH with 1 equiv. of NaEt3BH, while the opposite transformation occurs following iodomethane addition to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH. Facile interconversion between [(Ph2PPrPDI)MoI][I], (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH, and (Ph2PPrPDI)MoH2 is expected to guide future reactivity studies on this unique set of compounds.

Original languageEnglish
Pages (from-to)10024-10033
Number of pages10
JournalDalton Transactions
Volume45
Issue number24
DOIs
Publication statusPublished - 2016

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Molybdenum
Iodides
Reaction products
Hydrides
Deprotonation
Imines
Cyclic voltammetry
Paramagnetic resonance
Single crystals
Spectroscopy
Ligands
X ray diffraction
Atoms
Hydrogen
Geometry
Electrons
pyridine
methyl iodide
naphthalene

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Isolation of a bis(imino)pyridine molybdenum(i) iodide complex through controlled reduction and interconversion of its reaction products. / Pal, Raja; Cherry, Brian R.; Flores, Marco; Groy, Thomas L.; Trovitch, Ryan.

In: Dalton Transactions, Vol. 45, No. 24, 2016, p. 10024-10033.

Research output: Contribution to journalArticle

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title = "Isolation of a bis(imino)pyridine molybdenum(i) iodide complex through controlled reduction and interconversion of its reaction products",
abstract = "Analysis of previously reported [(Ph2PPrPDI)MoI][I] by cyclic voltammetry revealed a reversible wave at -1.20 V vs. Fc+/0, corresponding to the Mo(ii)/Mo(i) redox couple. Reduction of [(Ph2PPrPDI)MoI][I] using stoichiometric K/naphthalene resulted in ligand deprotonation rather than reduction to yield a Mo(ii) monoiodide complex featuring a Mo-C bond to the α-position of one imine substituent, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI. Successful isolation of the inner-sphere Mo(i) monoiodide complex, (Ph2PPrPDI)MoI, was achieved via reduction of [(Ph2PPrPDI)MoI][I] with equimolar Na/naphthalene. This complex was found to have a near octahedral coordination geometry by single crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy revealed an unpaired Mo-based electron which is highly delocalized onto the PDI chelate core. Attempts to prepare a Mo(i) monohydride complex upon adding NaEt3BH to (Ph2PPrPDI)MoI resulted in disproportionation to yield an equimolar quantity of (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH and newly identified (Ph2PPrPDI)MoH2. Independent preparation of (Ph2PPrPDI)MoH2 was achieved by adding 2 equiv. NaEt3BH to [(Ph2PPrPDI)MoI][I] and a minimum hydride resonance T1 of 176 ms suggests that the Mo-bound H atoms are best described as classical hydrides. Interestingly, (Ph2PPrPDI)MoH2 can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI upon iodomethane addition, while (Ph2PPrPDI)MoH2 is prepared from (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI in the presence of excess NaEt3BH. Similarly, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH with 1 equiv. of NaEt3BH, while the opposite transformation occurs following iodomethane addition to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH. Facile interconversion between [(Ph2PPrPDI)MoI][I], (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH, and (Ph2PPrPDI)MoH2 is expected to guide future reactivity studies on this unique set of compounds.",
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T1 - Isolation of a bis(imino)pyridine molybdenum(i) iodide complex through controlled reduction and interconversion of its reaction products

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AU - Trovitch, Ryan

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N2 - Analysis of previously reported [(Ph2PPrPDI)MoI][I] by cyclic voltammetry revealed a reversible wave at -1.20 V vs. Fc+/0, corresponding to the Mo(ii)/Mo(i) redox couple. Reduction of [(Ph2PPrPDI)MoI][I] using stoichiometric K/naphthalene resulted in ligand deprotonation rather than reduction to yield a Mo(ii) monoiodide complex featuring a Mo-C bond to the α-position of one imine substituent, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI. Successful isolation of the inner-sphere Mo(i) monoiodide complex, (Ph2PPrPDI)MoI, was achieved via reduction of [(Ph2PPrPDI)MoI][I] with equimolar Na/naphthalene. This complex was found to have a near octahedral coordination geometry by single crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy revealed an unpaired Mo-based electron which is highly delocalized onto the PDI chelate core. Attempts to prepare a Mo(i) monohydride complex upon adding NaEt3BH to (Ph2PPrPDI)MoI resulted in disproportionation to yield an equimolar quantity of (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH and newly identified (Ph2PPrPDI)MoH2. Independent preparation of (Ph2PPrPDI)MoH2 was achieved by adding 2 equiv. NaEt3BH to [(Ph2PPrPDI)MoI][I] and a minimum hydride resonance T1 of 176 ms suggests that the Mo-bound H atoms are best described as classical hydrides. Interestingly, (Ph2PPrPDI)MoH2 can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI upon iodomethane addition, while (Ph2PPrPDI)MoH2 is prepared from (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI in the presence of excess NaEt3BH. Similarly, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH with 1 equiv. of NaEt3BH, while the opposite transformation occurs following iodomethane addition to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH. Facile interconversion between [(Ph2PPrPDI)MoI][I], (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH, and (Ph2PPrPDI)MoH2 is expected to guide future reactivity studies on this unique set of compounds.

AB - Analysis of previously reported [(Ph2PPrPDI)MoI][I] by cyclic voltammetry revealed a reversible wave at -1.20 V vs. Fc+/0, corresponding to the Mo(ii)/Mo(i) redox couple. Reduction of [(Ph2PPrPDI)MoI][I] using stoichiometric K/naphthalene resulted in ligand deprotonation rather than reduction to yield a Mo(ii) monoiodide complex featuring a Mo-C bond to the α-position of one imine substituent, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI. Successful isolation of the inner-sphere Mo(i) monoiodide complex, (Ph2PPrPDI)MoI, was achieved via reduction of [(Ph2PPrPDI)MoI][I] with equimolar Na/naphthalene. This complex was found to have a near octahedral coordination geometry by single crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy revealed an unpaired Mo-based electron which is highly delocalized onto the PDI chelate core. Attempts to prepare a Mo(i) monohydride complex upon adding NaEt3BH to (Ph2PPrPDI)MoI resulted in disproportionation to yield an equimolar quantity of (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH and newly identified (Ph2PPrPDI)MoH2. Independent preparation of (Ph2PPrPDI)MoH2 was achieved by adding 2 equiv. NaEt3BH to [(Ph2PPrPDI)MoI][I] and a minimum hydride resonance T1 of 176 ms suggests that the Mo-bound H atoms are best described as classical hydrides. Interestingly, (Ph2PPrPDI)MoH2 can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI upon iodomethane addition, while (Ph2PPrPDI)MoH2 is prepared from (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI in the presence of excess NaEt3BH. Similarly, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI can be converted to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH with 1 equiv. of NaEt3BH, while the opposite transformation occurs following iodomethane addition to (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH. Facile interconversion between [(Ph2PPrPDI)MoI][I], (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoI, (κ6-P,N,N,N,C,P-Ph2PPrPDI)MoH, and (Ph2PPrPDI)MoH2 is expected to guide future reactivity studies on this unique set of compounds.

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