Between Elemental Match and Mismatch: From K Ge Sb to Salts of (Ge Sb ) , (Ge Sb ) , and (Ge Sb ).

The solid mixture "K GeSb" was shown to comprise single-crystalline K Ge Sb (1), a double salt of K [GeSb ] with carbonate-like [GeSb ] anions, and the metallic Zintl phase K Ge . Extraction of 1 with ethane-1,2-diamine in the presence of crypt-222 afforded [K(crypt-222)] salts of several novel binary Zintl anions: (Ge Sb ) (in 2), (Ge Sb ) (in 3), and in the presence of [AuMePPh ] also (Ge Sb ) (in 4). The anion in 2 represents a predicted, yet heretofore missing pseudo-tetrahedral anion. 4 comprises a cluster analogous to (Ge Bi ) and (Ga Bi ) , and thus one of the most Sb-rich binary p-block anions. The unprecedented cluster topology in 3 can be viewed as a defect-version of the one in 4 upon following a "dead end" of cluster growth. The findings indicate that Ge and Sb atoms are at the border of a well-matching and a mismatch elemental combination. We discuss the syntheses, the geometric structures, and the electronic structures of the new compounds.