Abstract
The spin states of a series of silicon- and carbon-bridged phenyl nitroxides were examined with respect to the temperature dependent ESR and SQUID measurements. Of those, a linear relationship between the ESR signal intensity and 1/T (T = absolute temperature) and an increase of χmolT along lowering T were observed for a compound having disilanylene-bridged m- and p-phenyl nitroxide units (Si2mp), indicating ferromagnetic spin-spin interaction in this molecule. In contrast to this, no clear intramolecular spin-spin interaction took place in the monosilanylene analogue (Si1mp). Mono- and disilanylene-bridged phenylnitroxides with p-, p- or m-, m-substitution (Si1pp,Si1mm, Si1pp, and Si2mm) exhibited the singlet ground state. The trisilanylene and siloxanylene bridges did not play an obvious role in the spin interaction, in either a ferro- or antiferromagnetic fashion, regardless of the substitution modes of the phenylenes. MO calculations on the model compounds provided a mechanistic interpretation for the high-spin interaction through the σ-π system.
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Iida, T., Ohshita, J., Uemura, T. et al. Spin-spin interaction between phenyl nitroxides through the σ-π system. Silicon Chemistry 1, 383–389 (2002). https://doi.org/10.1023/B:SILC.0000025597.03015.71
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DOI: https://doi.org/10.1023/B:SILC.0000025597.03015.71