Single crystal proton broadlineNMR of the Tutton salt K₂Co(SO₄)₂ 6H₂O is reported. From the analysis of the water proton dipolar tensor proton positions have been located, based on hydrogen bonding schemes. Besides, from an analysis of the paramagnetic proton shift tensors theg-tensor of the [Co(H₂O)₆] chromophore has been evaluated. Comparison with directly measuredg-tensor at 4·2 K is found to be good.

Single crystal EPR spectra of a natural mineral, apophyllite, containing VO(II) ion as an impurity have been investigated. The EPR spectra of the mineral, as obtained, was complex in nature, but was simplified by annealing the crystals at 490 K. The EPR parameters of the VO(II) species in the annealed crystal,g_∥ = 1.924 (2);g_⊥ = 1.983 (2);A_∥ = 18.35 (5); andA_⊥ = 7.24 (5)mT, are very close to a typical VO(II) impurity. Theoretically calculated line positions, using second-order hyperfine terms in the spin Hamiltonian with an axially symmetricg andA tensor values, agreed very well with the experimental ones. The EPR analysis of the annealed crystal has further revealed that the most preferred location of the VO(II) impurity is a substitutional Ca(II) site. The calculated bonding parameters and admixture coefficients indicate a fair amount of covalent bonding in the complex.