Unprecedented icosahedral clusters built of polyantimony: from single [Ni0.5@{Sb6Ni6(CO)8}]4- and [Ni@{Sb7Ni5(CO)6}]3- to the Sb84--linked dimer [(Sb8){Sb7Ni5(CO)4}2]6-

The reactions of K2ZnSb (0.234 mol) and Ni(CO)(2)(PPh3)(2) (x mol) in ethylenediamine (en) solutions of 18-crown-6 at 60 degrees C yielded half-centered [Ni-0.5@{Sb6Ni6(CO)(8)}](4-) (x = 0.023, 1) and fully embedded [Ni@{Sb7Ni5(CO)(6)}](3-) (x = 0.047, 2), wherein the chair-like Sb-6 subunit is bicapped by two Ni-3 triangles to form the single Sb6Ni6 icosahedron of 1 and by the triangular Ni2Sb and Ni-3 to form the single Sb7Ni5 icosahedron of 2. Surprisingly, a smaller amount of Ni(CO)(2)(PPh3)(2) (x = 0.016) led to the formation of the unprecedented dimer [(Sb-8){Sb7Ni5(CO)(4)}(2)](6-) (4), wherein the Sb7Ni5 icosahedral unit built of boat-like Sb-6, Ni2Sb and Ni-3 is linked together by the realgar-like Sb-8 to form the icosahedral dimer 4, providing a new way of thinking for the preparation of icosahedral oligomers/polymers. A similar hexa-anionic dimer (3) can be solely obtained using PBu4+ as the countercation under the same reaction conditions. The structure and bonding of this novel series of icosahedral clusters containing polyantimony were discussed for the first time.

Automated summary

The reaction of specific amounts of K2ZnSb and Ni(CO)(2)(PPh3)(2) in ethylenediamine solutions under certain conditions yielded different icosahedral clusters with varied polyantimony features, providing a novel approach for the synthesis of similar compounds.