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Structural Investigation of a Fully Ordered closo-Ge92– Cluster in the Compound [K+(2,2,2-crypt)]2Ge92–


  • Dedicated to Professor John D. Corbett on the occasion of his 85th birthday


[K+(2,2,2-crypt)]2Ge92– containing the deltahedral Zintl anion Ge92– has been isolated from a solution of K4Ge9 in ethylenediamine in the presence of 2,2,2-crypt, intended as an intermediate in mixed-cluster synthesis. The subsequent crystallographic characterisation shows the closo-Ge92– cluster unit to be tricapped trigonal-prismatic with a symmetry very close to D3h. Each Ge92– unit is surrounded by two 2,2,2-crypt units, each with a chelated K+ cation, viz. [K+(2,2,2-crypt)]. The structure characterisation of this ordered Ge92– cluster is surprisingly enough the first one reported. A chemical bonding analysis reveals two local minima of D3h symmetry, with that of lowest energy being highly similar to that resulting from the crystallographic analysis of low-temperature data. The cluster interaction scheme is based on highly delocalised bonding.