Synthesis, Structure, and Hydrogenolysis of Pyridine Dicarbene Iron Dialkyl Complexes

Stephan M. Rummelt, Jonathan M. Darmon, Renyuan Pony Yu, Peter Viereck, Tyler P. Pabst, Zoë R. Turner, Grant W. Margulieux, Shunlin Gu, Paul J. Chirik

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3 Scopus citations

Abstract

Two methods for the synthesis of bis(imidazol-2-ylidene)pyridine iron dialkyl complexes, (CNC)Fe(CH2SiMe3)2, have been developed. The first route consists of addition of 2 equiv of LiCH2SiMe3 to the iron dihalide complex (CNC)FeBr2, while the second relies on addition of the free CNC ligand to the readily prepared (py)2Fe(CH2SiMe3)2 (py = pyridine). With aryl-substituted CNC ligands, octahedral complexes of the type (ArCNC)Fe(CH2SiMe3)2(N2) (ArCNC = bis(arylimidazol-2-ylidene)pyridine) were isolated, where the dinitrogen ligand occupies the site trans to the pyridine of the CNC chelate. In contrast, the alkyl-substituted variant (tBuACNC)Fe(CH2SiMe3)2 (tBuACNC = 2,6-(tBu-imidazol-2-ylidene)2pyridine) was isolated as the five-coordinate compound lacking dinitrogen. Exposure of the (ArCNC)Fe(CH2SiMe3)2(N2) derivatives to an H2 atmosphere resulted in formation of the corresponding iron hydride complexes (ArCNC)FeH4. These compounds catalyzed hydrogen isotope exchange between the deuterated benzene solvent and H2, generating isotopologues and isotopomers of (ArCNC)Fe(Hn)(D4-n) (n = 0-4). When (3,5-Me2 MesCNC)Fe(CH2SiMe3)2(N2) (3,5-Me2 MesCNC = 2,6-(2,4,6-Me3-C6H2-imidazol-2-ylidene)2-3,5-Me2-pyridine) was treated successively with H2 and then N2, the corresponding reduced dinitrogen complex (3,5-Me2 MesCNC)Fe(N2)2 was isolated. The same product was also obtained following addition of pinacolborane to (3,5-Me2 MesCNC)Fe(CH2SiMe3)2(N2).

Original languageEnglish (US)
Pages (from-to)3159-3168
Number of pages10
JournalOrganometallics
Volume38
Issue number16
DOIs
StatePublished - Aug 26 2019

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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