The first fully characterized boron-functionalized heptaphosphide Zintl cluster, [(BBN)P<sub>7</sub>]<sup>2-</sup> ([<b>1</b>]<sup>2-</sup>), is synthesized by dehydrocoupling [HP<sub>7</sub>]<sup>2-</sup>. Dehydrocoupling is a previously unprecedented reaction pathway to functionalize Zintl clusters. [Na(18-c-6)]<sub>2</sub>[<b>1</b>] was employed as a transition metal-free catalyst for the hydroboration of aldehydes and ketones. Moreover, the greenhouse gas carbon dioxide (CO<sub>2</sub>) was efficiently and selectively reduced to methoxyborane. This work represents the first examples of Zintl catalysis where the transformation is transition metal-free and where the cluster is noninnocent.
