Critical behavior in ferromagnetic ${\mathrm{F}\mathrm{e}\left[{\mathrm{S}}_2\mathrm{C}{\mathrm{N}\left({\mathrm{C}}_2{\mathrm{H}}_5\right)}_2\right]}_2$C1

Magnetic-susceptibility and sublattice-magnetization data are analyzed with correction-to-scaling terms included. Critical exponents $\gamma =1.165\mathrm{}\pm 0.03$ and $\beta =0.245\mathrm{}\pm 0.02$ are deduced, with the assumption of modified power-law expressions ${\chi }_0=\Gamma t^{-\gamma }(1+a_{\chi }{t}^{\Delta })$ and $m\left(\frac{T}{T_C}\right)=B{\mathrm{}\left|t\right|\mathrm{}}^{\beta }(1+a_M{\mathrm{}\left|t\right|\mathrm{}}^{\Delta })$ with $\Delta =0.493\mathrm{}$, $a_{\chi }=0.207\mathrm{}$, and $a_M=0.156\mathrm{}$. $\Gamma =1.47\mathrm{}\pm 0.07$ emu/mole, or ${\Gamma }_r=1.07\mathrm{}\pm 0.05$ for the reduced susceptibility, and $B=1.30\mathrm{}\pm 0.05$ are also determined. ${\Gamma }_r$ is larger than most theoretical estimates for the Ising model on various three-dimensional lattices. $B$ is smaller than theoretical results. The amplitude ratio $\frac{{\Gamma }_r}{B}$ is about 0.83, larger than theoretical values for this nonuniversal but only weakly lattice-dependent quantity. Heat-capacity data are sparse and less reliably analyzed, but suggest abnormally large values of $\alpha$ (> 0.3) and rather small values of $A$ (0.2 to 0.5) in $\frac{C}{R}=A{t}^{-\alpha }+B^{\prime }$. Including a correction-to-scaling term does not alter this conclusion. The ratio $R_C=A{B}^{-2\mathrm{}}{\Gamma }_r$ is in the range 0.12 to 0.33, substantially less than theoretical values for this universal quantity. A straightforward explanation for the unusual critical behavior is not apparent.