We present a comparative Raman scattering study of metallic rutile oxides ($\mathrm{Ru}{\mathrm{O}}_2$ and $\mathrm{Ir}{\mathrm{O}}_2$) and insulating rutiles ($\mathrm{Ti}{\mathrm{O}}_2$ and $\mathrm{Sn}{\mathrm{O}}_2$). Temperature-dependent Raman spectra reveal that metallic compounds exhibit pronounced phonon frequency hardening $[\omega \left(11K\right)-\omega \left(300K\right)=\mathrm{\Delta }\omega \approx 6-10\mathrm{c}{\mathrm{m}}^{-1}]$, whereas the insulating rutiles show only modest hardening $\mathrm{\Delta }\omega \approx 1-3\mathrm{c}{\mathrm{m}}^{-1}$. In contrast, the linewidth changes $\mathrm{\Delta }\mathrm{\Gamma }\approx 1–7\mathrm{c}{\mathrm{m}}^{-1}$ do not display a systematic metallic-insulating classification. Fits with the conventional Klemens anharmonic decay model reproduce the overall temperature trends but yield inconsistent anharmonic parameters for the metallic compounds when benchmarked against insulating rutile analogs. A modified Klemens framework, incorporating an additional $T^2$ correction to the phonon frequency arising from the electronic contribution to the phonon self-energy, quantitatively accounts for the enhanced renormalization observed in metallic systems. These results establish finite nonadiabatic electron-phonon coupling in metallic rutiles and demonstrate that phonon renormalization can be identified even in the absence of observable Fano asymmetry in the phonon line shapes.

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• Electron-phonon coupling
• Lattice dynamics
• Altermagnets
• Transition metal oxides
• Raman spectroscopy