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The electronic g factor carries highly useful information about the electronic structure of a paramagnetic species, such as spin-orbit coupling and dia- or paramagnetic (de-)shielding due to local fields of surrounding electron pairs. However, in many cases, a near “spin-only” case is observed, in particular for light elements, necessitating accurate and precise measurement of the g factors. Such measurement is typically impeded by a “chicken and egg situation”: internal or external reference standards are used for relative comparison of electron paramagnetic resonance (EPR) Larmor frequencies. However, the g factor of the standard itself usually is subject to a significant uncertainty which directly limits the precision and/or accuracy of the sought after sample g factor. Here, we apply an EPR reference-free approach for determining the g factor of atomic nitrogen trapped within the endohedral fullerene C 60 :N@C 60 in its polycrystalline state by measuring the 1 H NMR resonance frequency of dispersing toluene at room temperature. We found a value of g = 2.00204 ( 4 ) with a finally reached relative precision of ∼20 ppm. This accurate measurement allows us to directly compare the electronic properties of N@C 60 to those found in atomic nitrogen in the gas phase or trapped in other solid matrices at liquid helium temperature. We conclude that spin-orbit coupling in N@C 60 at room temperature is very similar in magnitude and of same sign as found in other inert solid matrices and that interactions between the quartet spin system and the C 60 molecular orbitals are thus negligible. [ABSTRACT FROM AUTHOR]

As a means of obtaining precise quantitative data in 2D NMR spectroscopy, the use of an electronic reference signal (ERETIC) has been examined. The results presented demonstrate that the ERETIC method can be used in different situations encountered in 2D-NMR spectroscopy: homonuclear and heteronuclear spectra, phased or magnitude mode, symmetrization. The main restriction to introducing ERETIC in 2D spectra could be the need for several spectrometer channels. However, most modern NMR spectrometers are equipped with at least three channels, that allows the implementation of the ERETIC method as reference for 2D-NMR spectroscopy without needing any hardware modification. [Copyright &y& Elsevier]