Ac. Kolbert et al., DETERMINATION OF THE SPIN-DENSITY DISTRIBUTION IN THE ORGANIC CONDUCTOR DMTM(TCNQ)(2) WITH C-13 MAGIC-ANGLE-SPINNING NMR, Molecular physics, 91(4), 1997, pp. 725-730
C-13 magic angle spinning (MAS) NMR experiments on the organic conduct
or N,N-dimethylthiomorpholinium bis-tetracyanoquino-dimethane [DMTM(TC
NQ)(2)] isotopically enriched at the position of the C-2 carbons of TC
NQ are reported. Two isotropic resonances are resolved above the struc
tural phase transition at 272 K, both exhibiting large positive isotro
pic and anisotropic Knight shifts. Sideband analysis of the MAS spectr
a has yielded the complete Knight shift tensors above T-c, in the insu
lating state. From the Knight shifts the hyperfine couplings and spin
densities at the C-2 sites were calculated and were found to be in goo
d agreement with molecular calculations. Below T-c, the sideband patte
rn displays two jets of C-13-2 lines indicating a spin density distrib
ution between two sites of 0.59:0.41.