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Published March 1, 1993 | public
Journal Article

Evaluation of potential ferromagnetic coupling units: the bis(TMM) [bis(trimethylenemethane)] approach to high-spin organic molecules


Four new hydrocarbon tetraradicals, 1-4, each composed of two triplet trimethylenemethane (TMM) subunits linked by a potential ferromagnetic coupling unit (FC), were synthesized and characterized by variable-temperature electron paramagnetic resonance (EPR) spectroscopy. Simulation of the EPR powder spectra and a priori calculation of the zero-field splitting parameters aided spectral assignment. The Heisenberg Hamiltonian appears to quantitatively model relative spin-state energies in 1-4. In three cases ferromagnetic coupling was achieved, as evidenced by quintet ground states in the resulting tetraradicals. In one case, strong evidence for antiferromagnetic coupling was obtained.

Additional Information

© 1993 American Chemical Society. Received September 17, 1992. We thank Dr. Angelo J. Di Bilio for providing us a copy of his program for EPR simulation, and Dr. Di Billo and Dr. Sunney I. Chan for fruitful discussions of EPR results and spectral simulations. This work was funded by the National Science Foundation, to whom we are grateful.

Additional details

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