Determination of the spin density distribution in the organic conductor DMTM(TCNQ)2 with 13C magic angle spinning NMR

13C magic angle spinning (MAS) NMR experiments on the organic conductor N , N -dimethylthiomorpholinium bis-tetracyanoquino-dimethane [DMTM(TCNQ) ]isotopically enriched at the position of the C-2 carbons of TCNQ are reported. Two isotropic resonances are resolved above the structural phase transition at 272 K, both exhibiting large positive isotropic and anisotropic Knight shifts. Sideband analysis of the MAS spectra has yielded the complete Knight shift tensors above T , in the insulating state. From the Knight shifts the hyperfine couplings and spin densities at the C-2 sites were calculated and were found to be in good agreement with molecular calculations. Below T , the sideband pattern displays two sets of 13C-2 lines indicating a spin density distribution between two sites of 0.59 2 c c 0.41. :