Temperature dependences of the chemical shift and spin-lattice relaxation time in the rotating frame T-1 rho were measured for H-1 and C-13 nuclei in mixed crystals of the form [N(CH3)(4)](2)Zn1-x CoxCl4 (x = 0, 0.5, 0.7, 0.9, and 1). The mixed crystals varied in color according to the amount of Co2+ ions, whereas the phase transition temperatures remained nearly unchanged. [N(CH3)(4)](2)ZnCl4 and [N(CH3)(4)](2)CoCl4 crystals contain two nonequivalent types of a-N(CH3)(4) and b-N(CH3)(4). The two crystallographically different ions a-N(CH3)(4) and b-N(CH3)(4) were distinguished using C-13 CP/MAS NMR spectroscopy. The NMR spectrum and T-1 rho for H-1 and C-13 in case of x = 0.5 and x = 0.7 were similar to those for [N(CH3)(4)](2)ZnCl4, whereas those for x = 0.9 were absolutely different. Additionally, [N(CH3)(4)](2)Zn0.1Co0.9Cl4 exhibited the structural properties of both [N(CH3)(4)](2)ZnCl4 and [N(CH3)(4)](2)CoCl4. (C) 2016 Elsevier B.V. All rights reserved.