A Zintl Cluster for Transition Metal-Free Catalysis: C═O Bond Reductions.

The first fully characterized boron-functionalized heptaphosphide Zintl cluster, [(BBN)P 7 ] 2- ([ 1 ] 2- ), is synthesized by dehydrocoupling [HP 7 ] 2- . Dehydrocoupling is a previously unprecedented reaction pathway to functionalize Zintl clusters. [Na(18-c-6)] 2 [ 1 ] was employed as a transition metal-free catalyst for the hydroboration of aldehydes and ketones. Moreover, the greenhouse gas carbon dioxide (CO 2 ) 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.