Stable carbene and diazoalkane complexes of the same complex system. Synthesis, structure, and reactivity of PNP-Ru(II) fluorenylidene and diazofluorene complexes

Jing Zhang, Mark Gandelman, Linda J W Shimon, David Milstein

Research output: Contribution to journalArticle

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Abstract

The choice of synthetic methodology leads to either carbene or diazoalkane complexes of the same system. Thus, treatment of RuCl2(PPh 3)3 with 9-diazofluorene followed tBu-PNP (tBu-PNP = 2,6-bis(diiert-butylphosphinomethyl)pyridine) resulted in loss of dinitrogen and formation of the Ru(II) fluorenylidene complex 1. On the other hand, treatment of the tBu-PNP Ru(II) dinitrogen complex 4 with 9-diazofluorene resulted in the formation of η1-dizaofluorene Ru(II) complex 5, in which the diazo unit remains intact. The cationic Ru(II) carbene complex 2 was obtained by the reaction of 1 with 1 equiv of AgBF 4 or HBF4. Chloride dissociation to form a 16-e cationic carbene complex 3 took place also upon refluxing of 1 in toluene. The five-coordinated, unsaturated, charge-neutral diiodide Ru(II) complex 6 was obtained by reaction of 4 with NaI. Complex 6 is stabilized by a C-H agostic interaction, as observed by X-ray crystallography. Reaction of 4 with NaBEt3H followed by 9-dizaofluorene resulted in a novel η1- diazenofluorene Ru(II) complex 7, accompanied by the migration of one hydrogen atom from the metal center to the coordinated nitrogen atom of the diazenofluorene unit. Heating complex 7 at 65°C resulted in sp2 C-H activation followed by elimination of dihydrogen to form the chelated, β-carbon coordinated diazenofluorene ruthenium complex 8. Complexes 1, 2, 5, 6, and 8 were structurally characterized by X-ray crystallography.

Original languageEnglish
Pages (from-to)3526-3533
Number of pages8
JournalOrganometallics
Volume27
Issue number14
DOIs
Publication statusPublished - Jul 28 2008

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carbenes
complex systems
Large scale systems
reactivity
X ray crystallography
crystallography
synthesis
Atoms
Ruthenium
Toluene
nitrogen atoms
ruthenium
toluene
Chlorides
Hydrogen
elimination
hydrogen atoms
pyridines
x rays
Nitrogen

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Organic Chemistry

Cite this

Stable carbene and diazoalkane complexes of the same complex system. Synthesis, structure, and reactivity of PNP-Ru(II) fluorenylidene and diazofluorene complexes. / Zhang, Jing; Gandelman, Mark; Shimon, Linda J W; Milstein, David.

In: Organometallics, Vol. 27, No. 14, 28.07.2008, p. 3526-3533.

Research output: Contribution to journalArticle

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title = "Stable carbene and diazoalkane complexes of the same complex system. Synthesis, structure, and reactivity of PNP-Ru(II) fluorenylidene and diazofluorene complexes",
abstract = "The choice of synthetic methodology leads to either carbene or diazoalkane complexes of the same system. Thus, treatment of RuCl2(PPh 3)3 with 9-diazofluorene followed tBu-PNP (tBu-PNP = 2,6-bis(diiert-butylphosphinomethyl)pyridine) resulted in loss of dinitrogen and formation of the Ru(II) fluorenylidene complex 1. On the other hand, treatment of the tBu-PNP Ru(II) dinitrogen complex 4 with 9-diazofluorene resulted in the formation of η1-dizaofluorene Ru(II) complex 5, in which the diazo unit remains intact. The cationic Ru(II) carbene complex 2 was obtained by the reaction of 1 with 1 equiv of AgBF 4 or HBF4. Chloride dissociation to form a 16-e cationic carbene complex 3 took place also upon refluxing of 1 in toluene. The five-coordinated, unsaturated, charge-neutral diiodide Ru(II) complex 6 was obtained by reaction of 4 with NaI. Complex 6 is stabilized by a C-H agostic interaction, as observed by X-ray crystallography. Reaction of 4 with NaBEt3H followed by 9-dizaofluorene resulted in a novel η1- diazenofluorene Ru(II) complex 7, accompanied by the migration of one hydrogen atom from the metal center to the coordinated nitrogen atom of the diazenofluorene unit. Heating complex 7 at 65°C resulted in sp2 C-H activation followed by elimination of dihydrogen to form the chelated, β-carbon coordinated diazenofluorene ruthenium complex 8. Complexes 1, 2, 5, 6, and 8 were structurally characterized by X-ray crystallography.",
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T1 - Stable carbene and diazoalkane complexes of the same complex system. Synthesis, structure, and reactivity of PNP-Ru(II) fluorenylidene and diazofluorene complexes

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