Single-Crystal Paramagnetic Resonance Studies of V(II), Mn(II), and Ni(II) in CsMgCl3 and the Crystal Structure of CsMgCl3

Abstract

The single‐crystal electron spin resonance spectra of (VII), Mn(II), and Ni(II) are reported in the diamagnetic lattice CsMgCl₃ at 298 and 77°K. The structure of the host lattice CsMgCl₃ is also reported. The crystal system is hexagonal, space group ${\text{P6}}_3\mathrm{/m\; mc}$ . The basic structural feature is the linear array of [MgCl₆]⁴⁻ octahedra sharing faces directed along the hexagonal $c$ axis. The crystallographic site symmetry at the Mg²⁺ ions is $D_{3_d}$ . The spin resonance spectra of the doped salts Cs[Mg_1−x, V_x]Cl₃, Cs[Mg_1−x, Mn_x]Cl₃, and Cs[Mg_1−x, Ni_x]Cl₃, where $x$ is small, can be readily explained in terms of the axial field Hamiltonian: ${\mathrm{H\hspace{0.17em}=\hspace{0.17em}\beta [g\Vert H}}_z{S}_z{\mathrm{\hspace{0.17em}+\hspace{0.17em}g\perp (H}}_x{S}_x{\mathrm{\hspace{0.17em}+\hspace{0.17em}H}}_y{S}_y{\mathrm{)]\hspace{0.17em}+\hspace{0.17em}D[S}}_z^2\mathrm{\hspace{0.17em}-\hspace{0.17em}}\frac{1}{3}{\text{S(S\hspace{0.17em}+\hspace{0.17em}1)]\hspace{0.17em}+\hspace{0.17em}AS}}_z{I}_z{\mathrm{\hspace{0.17em}+\hspace{0.17em}B(S}}_x{I}_x{\mathrm{\hspace{0.17em}+\hspace{0.17em}S}}_y{I}_y)$ . The principal measured quantities are, respectively: V(II)(77°K), $\text{g‖\hspace{0.17em}=\hspace{0.17em}1.9740, g⊥\hspace{0.17em}=\hspace{0.17em}1.9760, D(}\mathrm{gauss}\text{)\hspace{0.17em}=\hspace{0.17em}931, A(}\mathrm{gauss}\text{)\hspace{0.17em}=\hspace{0.17em}82.3, B(}\mathrm{gauss}\text{)\hspace{0.17em}=\hspace{0.17em}79.8}$ ; Mn(II)(77°K), $\text{g‖\hspace{0.17em}=\hspace{0.17em}2.0016, g⊥\hspace{0.17em}=\hspace{0.17em}2.0015, D(}\mathrm{gauss}\text{)\hspace{0.17em}=\hspace{0.17em}313, A(}\mathrm{gauss}\text{)\hspace{0.17em}=\hspace{0.17em}86.5,}\mathrm{B}(\mathrm{gauss}\text{)\hspace{0.17em}=\hspace{0.17em}86.5}$ ; Ni(II)(77°K), $\text{g‖\hspace{0.17em}=\hspace{0.17em}2.257, g⊥\hspace{0.17em}=\hspace{0.17em}2.241, D(}\mathrm{gauss}\text{)\hspace{0.17em}=\hspace{0.17em}18 980}$ .