The appearance of superconductivity in ${\mathrm{FePSe}}_3$ and its absence in ${\mathrm{MnPSe}}_3$ has been linked to pressure-driven magnetic quenching from a high-spin to low-spin state, which fills the $T_{2\mathrm{g}}$ orbital with Fe $3d^6$ electrons. However, the exact mechanisms responsible for emergent superconductivity remain ambiguous due to the coexistence of intra/interlayer collapse and the persistence of residual local magnetic moments. To address this, we study ${\mathrm{ZnPSe}}_3$, where $\mathrm{Z}{\mathrm{n}}^{2+}$ has a fully filled $3d^{10}$ configuration. Under pressure, ${\mathrm{ZnPSe}}_3$ shows an isostructural transition without sudden lattice contractions, confirming the absence of spin-crossover effects. It transitions from a semiconductor to a metal at 35 GPa, followed by the onset of superconductivity at 3.4 K. Further increase in pressure leads to elevated $T_{\mathrm{c}}$ up to 7.2 K, which exceeds the value achieved in pressurized ${\mathrm{FePSe}}_3$ due to the lack of local magnetization in the Zn compound. Therefore, ${\mathrm{ZnPSe}}_3$ serves as a representative system among the $M\mathrm{P}{X}_3$ ($M$ = metal, $X$ = S/Se) family of materials, enabling separation of effects related to magnetism and superconductivity. Our findings demonstrate that spin crossover does not constitute a prerequisite for superconductivity within $M\mathrm{P}{X}_3$ materials.

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• High-pressure studies
• Superconductivity
• van der Waals systems
• Raman spectroscopy
• X-ray diffraction