Hydrogen-rich compounds that exhibit high-temperature superconductivity typically require extreme pressures, which severely limits their practical applicability. Recent theoretical predictions of the complex hydride ${\mathrm{Mg}}_2{\mathrm{IrH}}_6$ have introduced a new family of ${\mathit{M}}_2{\mathit{X}\mathrm{H}}_6$-type hydrides, highlighting the potential for high-temperature superconductivity at near-ambient pressure. Motivated by this, we have performed high-throughput first-principles investigations of the ${\mathit{M}}_2{\mathit{X}\mathrm{H}}_6$ family (M = IA, IIA, IIIA, IIB metals; X = B, C, N) to identify dynamically stable hydrides and explore their superconducting properties. Eleven boron-based hydrides, ${\mathit{M}}_2{\mathrm{BH}}_6$ (M = Li, Na, K, Rb, Cs, Ca, Sr, Ba, Sc, Y, La), featuring ${\mathrm{BH}}_6$ octahedral units have been identified. Notably, ${\mathrm{Li}}_2{\mathrm{BH}}_6$ is dynamically stable down to 16 GPa and exhibits a superconducting critical temperature of 121.25 K. Electronic structure and phonon analyses indicate that high-frequency hydrogen vibrations from strong B–H covalent bonding, reinforced by light Li atoms, dominate the electron–phonon coupling. In contrast, noble-metal-based ${\mathrm{Li}}_2{\mathit{X}\mathrm{H}}_6$ compounds (X = Cu, Ag, Au) exhibit distinct superconducting mechanisms, driven by $d$ electrons at the Fermi level and low-frequency metal vibrations. These findings expand the compositional space of the ${\mathit{M}}_2{\mathit{X}\mathrm{H}}_6$ family and highlight ${\mathrm{Li}}_2{\mathrm{BH}}_6$ as a promising candidate for near-ambient-pressure high-$T_c$ superconductivity.

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• Electronic structure
• Superconductivity
• Hydrides
• Density functional theory