Bellows SM, Brennessel WW, Holland PL. Effects of Ligand Halogenation on the Electron Localization, Geometry and Spin State of Low-Coordinate (β-Diketiminato)iron Complexes.
Eur J Inorg Chem 2016;
2016:3344-3355. [PMID:
28835739 PMCID:
PMC5563838 DOI:
10.1002/ejic.201600112]
[Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Indexed: 11/05/2022]
Abstract
This contribution explores the influences of incorporating electron-withdrawing CF3 and halide groups into β-diketiminate iron complexes of tetrazene and isocyanide. The synthesis of a new halogenated β-diketimine (LCF3,ClH) was accomplished via two different methods, including a novel microwave-assisted synthesis that improves the yield of the difficult condensation. Treatment of an iron(II) complex of this ligand with reductant and azide gives two diiron complexes with novel tetrazenes as bridging ligands. Structural and Mössbauer data show that the bridging tetrazene is a radical anion. The halogenation of the supporting ligand also influences iron(I) complexes of the type LFe(CNtBu)2, which are low-spin and square-planar with alkyl substituents but high-spin and pseudotetrahedral with halogen substituents. DFT calculations suggest that the changes from halogenation come from a combination of steric and electronic effects, and that the electronic influence of ligand halogenation is minor.
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