Issue 11, 1998

Response to steric constraint in azacryptate and related complexes of iron-(II) and -(III) *

Abstract

Iron(II) cryptates, where the FeII is in the high-spin S = 2 electronic configuration, even with six sp2 N-donors, and iron(III) cryptates adopting the intermediate spin S = [fraction three-over-two] state have been prepared. The structure of a high-spin iron(II) cryptate utilising six sp2 N-donors shows long metal–ligand distances which effectively destabilise the low-spin 1Ag configuration. Comparison is made between iron(III) cryptates, a less sterically constrained podand complex of the same donor set, and analogous N4O2 polychelates, which are respectively intermediate-, high- and low-spin or S = [fraction five-over-two] ←→ S = ½ spin crossover systems. The Mössbauer spectra of the iron(III) cryptates and analogous podate are remarkably similar, despite their different spin states, suggesting covalency in the podate binding. The crystal structure of the podate supports this conclusion, as the iron–ligand donor distances are short for high-spin FeIII.

Supplementary files

Article information

Article type
Paper

J. Chem. Soc., Dalton Trans., 1998, 1837-1844

Response to steric constraint in azacryptate and related complexes of iron-(II) and -(III) *

F. Anthony Deeney, C. J. Harding, G. G. Morgan, V. McKee, J. Nelson, S. J. Teat and W. Clegg, J. Chem. Soc., Dalton Trans., 1998, 1837 DOI: 10.1039/A801046C

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