The reactions of Group 13 chlorides (BCl₃, AlCl₃, GaCl₃, InCl₃) with bases are predicted well by the HSAB principle. Which of the following is the predicted order of reactivity (completeness of adduct formation) of these compounds toward P(CH₂CH₃)₃?

Question

Quizplus · Accepted Answer

The HSAB (Hard and Soft Acids and Bases) principle suggests that hard acids prefer to react with hard bases, while soft acids prefer to react with soft bases. In the context of Group 13 chlorides reacting with a phosphine base (P(CH3)3), the reactivity order is determined by the acid-base interaction strength. Boron (B) is the hardest acid among the given options, followed by aluminum (Al), gallium (Ga), and then indium (In) being the softest. Since P(CH3)3 is considered a soft base, it will have a stronger interaction with the softer acids. Therefore, the reactivity order (completeness of adduct formation) is BCl3 < AlCl3 < GaCl3 < InCl3, matching option C.

The Reactions of Group 13 Chlorides (BCl3, AlCl3, GaCl3, InCl3)

The Reactions of Group 13 Chlorides (BCl₃, AlCl₃, GaCl₃, InCl₃)