Temperature Dependence of the ESR Spectrum of NiSnCl6.6H2O.

The electron spin resonance spectrum of single-crystal NiSnCl6-6H2O has been measured at X-band at temperatures between 4.2 and 370 K. The results are consistent with low-temperature magnetic and thermal measurements that indicate a singlet ground state for the NiH2O62 complex. Linewidth measurements below 300 K indicate contributions from spin-lattice relaxation and from both isotropic and anisotropic exchange. Linewidth measurements in the vicinity of D 0 exhibit narrowing due to vanishing of the isotropic exchange contribution and broadening by cross-relaxation.