Synthesis of a bulky bis(imino)pyridine compound: a methodology for systematic variation of steric bulk and energetic implications for metalation
- 1 January 2009
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Dalton Transactions
- No. 7,p. 1214-1222
- https://doi.org/10.1039/b815987d
Abstract
A new bis(imino)pyridine compound, 2,6-{(2,6-Me2-C6H3)NC(t-Bu)}2C5H3N (6), has been synthesized with t-butyl substituents on the imino carbon atoms. The stepwise synthetic method for assembly of this compound is novel. Compound 6 and its synthetic precursor, mono(imino)pyridine 3, have been characterized using single-crystal X-ray diffraction. Metalation attempts of 6 using iron(II) chloride under forcing conditions does not yield the desired iron(II) chloride complex; the use of refluxing acetic acid solvent provides a minimal amount of a paramagnetic species that has been characterized by NMR spectroscopy and magnetic susceptibility (NMR method). Computational methods have been used to evaluate the relative energies of three conformations of bis(imino)pyridine ligands with varying alkyl substitution at the imino carbon positions. The relative energies of these closed, open and open-planar conformations of 6 reveal a thermodynamic argument for the difficulty in metalation of 6, as compared to related ligands with less steric hindrance at the imino carbon atoms.Keywords
This publication has 49 references indexed in Scilit:
- Mechanistic Insight into NN Cleavage by a Low-Coordinate Iron(II) Hydride ComplexJournal of the American Chemical Society, 2007
- Iron-based ethylene polymerization catalysts supported by bis(imino)pyridine ligands: Derivatization via deprotonation/alkylation at the ketimine methyl positionJournal of Molecular Catalysis A: Chemical, 2007
- Simultaneous Polymerization and Schulz−Flory Oligomerization of Ethylene Made Possible by Activation with MAO of a C1-Symmetric [2,6-Bis(arylimino)pyridyl]iron Dichloride PrecursorOrganometallics, 2004
- Dramatic Effect of Heteroatom Backbone Substituents on the Ethylene Polymerization Behavior of Bis(imino)pyridine Iron CatalystsInorganic Chemistry, 2004
- 2,4,6-Tri-tert-butylphenyl and 2,4-di-tert-butyl-6-methylphenyl groups: Look similar, react differentlyHeteroatom Chemistry, 2002
- Ethylene polymerization by iron complexes with symmetrical and unsymmetrical ligandsPolymer International, 2002
- N‐Pyrrolyl‐[N,N,N]‐bis(imino)pyridyl iron(II) and cobalt(II) olefin polymerization catalystsApplied Organometallic Chemistry, 2002
- Isotactic-specific polymerization of propene with an iron-based catalyst: polymer end groups and regiochemistry of propagationMacromolecular Rapid Communications, 1998
- β-Diiminato Complexes of VIII and TiIII – Formation and Structure of Stable Paramagnetic Dialkylmetal CompoundsEuropean Journal of Inorganic Chemistry, 1998
- A convenient method for estimation of alkyllithium concentrationsThe Journal of Organic Chemistry, 1976