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Updated: Sep 15, 2025

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Published on: February 7, 2017
An Ytterbium-Pyrazine Square [(C5H4Me)2YbIII(pyz•-)]4 Formed by Reversible Electron Transfer and Concomitant
Himanshu Gupta1, Asmita Sen2, Patrick W Smith3
1Vagelos Laboratory for Energy Science and Technology, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
Abstract:
Pyrazine (pyz) has been used extensively in coordination chemistry to manifest electron delocalization in mixed-valent compounds and strongly coupled materials. In the current work, using a YbII precursor, [(C5H4Me)2YbII(THF)2] (1), a molecular square [(C5H4Me)2YbIII(pyz•-)]4·1/2(C7H5F3) (2) was synthesized by metal-ligand redox cooperativity. Complex 2 shows evidence of charge transfer from YbII to pyrazine in a range of studies including structural analysis, magnetometry, vibrational spectroscopy, X-ray absorption near-edge structure spectroscopy, and electronic structure calculations. DFT calculations support the assignment of low-energy bands in the UV-vis spectrum as pyrazine-SOMO-to-metal-4f charge transfer. Magnetic studies reveal a Yb-pyz•- exchange coupling of -3.6 cm-1 and pyz•--pyz•- coupling of -18.6 cm-1 for the radical bridged Yb-square complex.
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