Jump to main content
Jump to site search
PLANNED MAINTENANCE Close the message box

Scheduled maintenance upgrade on Thursday 4th of May 2017 from 8.00am to 9.00am (BST).

During this time our websites will be offline temporarily. If you have any questions please use the feedback button on this page. We apologise for any inconvenience this might cause and thank you for your patience.

Issue 22, 2011
Previous Article Next Article

Synthesis and Characterization of Sterically Encumbered β-Ketoiminate Complexes of Iron(II) and Zinc(II)

Author affiliations


The synthesis, structure, and spectroscopic signatures of a series of four-coordinate iron(II) complexes of β-ketoiminates and their zinc(II) analogues are presented. An unusual five-coordinate iron(II) triflate with three oxygen bound protonated β-ketoimines is also synthesized and structurally characterized. Single-crystal X-ray crystallographic analysis reveals that the deprotonated bis(chelate)metal complexes are four-coordinate with various degrees of distortion depending on the degree of steric bulk and the electronics of the metal center. Each of the high-spin iron(II) centers exhibits multiple electronic transitions including ligand π to π*, metal-to-ligand charge transfer, and spin-forbidden d-d bands. The 1H NMR spectra of the paramagnetic high-spin iron(II) centers are assigned on the basis of chemical shifts, longitudinal relaxation times (T1), relative integrations, and substitution of the ligands. The electrochemical studies support variations in the ligand strength. Parallel mode EPR measurements for the isopropyl substituted ligand complex of iron(II) show low-field resonances (g > 9.5) indicative of complex aggregation or crystallite formation. No suitable solvent system or glassing mixture was found to remedy this phenomenon. However, the bulkier diisopropylphenyl substituted ligand exhibits an integer spin signal consistent with an isolated iron(II) center [S = 2; D = −7.1 ± 0.8 cm−1; E/D = 0.1]. A tentative molecular orbital diagram is assembled.

Graphical abstract: Synthesis and Characterization of Sterically Encumbered β-Ketoiminate Complexes of Iron(ii) and Zinc(ii)

Back to tab navigation
Please wait while Download options loads

Supplementary files

Publication details

The article was received on 07 Jan 2011, accepted on 30 Mar 2011 and first published on 04 May 2011

Article type: Paper
DOI: 10.1039/C1DT10024F
Citation: Dalton Trans., 2011,40, 5881-5890
  •   Request permissions

    Synthesis and Characterization of Sterically Encumbered β-Ketoiminate Complexes of Iron(II) and Zinc(II)

    D. M. Granum, P. J. Riedel, J. A. Crawford, T. K. Mahle, C. M. Wyss, A. K. Begej, N. Arulsamy, B. S. Pierce and M. P. Mehn, Dalton Trans., 2011, 40, 5881
    DOI: 10.1039/C1DT10024F

Search articles by author