Spin states, bonding and magnetism in mixed valence iron(0)–iron(II) complexes

11 November 2021, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


We report the synthesis of two complexes featuring unsupported Fe–Fe bonds between a diketiminate/dialdiminate-coordinated iron site and a cyclopentadienyl dicarbonyl iron site. Mössbauer spectroscopy, SQUID magnetometry and computational analysis indicate that the most accurate electronic structure description is with the Fe(CO)2Cp site as low spin iron(0), and it acts as a Lewis base toward the high spin iron(II) of the LFe fragment which is a Lewis acid. In both compounds, the three-coordinate high-spin iron(II) site has large zero-field splitting (zfs), up to D = –50 cm–1.


Metal-metal bond
iron complex
spin state

Supplementary materials

Supporting Information
Experimental and computational data


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