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Why is lithium aluminum hydride a stronger reducing agent than many other compounds?

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Lithium aluminum hydride (LiAlH $_{4}$ ) is a powerful reducing agent used extensively in chemistry to reduce various organic compounds, such as converting carboxylic acids to alcohols.123

Its effectiveness as a reducing agent is primarily due to the presence of the tetrahydridoaluminate anion (AlH $_{4}^{-}$ ). In this compound, the aluminum-hydrogen bond is highly hydridic, meaning it is exceptionally capable of donating hydride ions (H $^{-}$ ) to other species.4

While both borohydrides (such as NaBH $_{4}$ ) and aluminohydrides (such as LiAlH $_{4}$ ) are well-known reducing agents, their chemical stabilities differ. The boron compounds are generally more thermally and chemically stable than the aluminum compounds. Because the aluminum-based compounds are less stable, they are more reactive, which contributes to their status as stronger reducing agents compared to many other compounds.4