Atom Exchange Versus Reconstruction: (Ge<sub><i>x</i></sub>As<sub>4−<i>x</i></sub>)<sup><i>x</i>−</sup> (<i>x=</i>2, 3) as Building Blocks for the Supertetrahedral Zintl Cluster [Au<sub>6</sub>(Ge<sub>3</sub>As)(Ge<sub>2</sub>As<sub>2</sub>)<sub>3</sub>]<sup>3−</sup>
Fuxing Pan, Lukas Guggolz, Florian Weigend, Stefanie Dehnen
Abstract
Abstract The Zintl anion (Ge 2 As 2 ) 2− represents an isostructural and isoelectronic binary counterpart of yellow arsenic, yet without being studied with the same intensity so far. Upon introducing [(PPh 3 )AuMe] into the 1,2‐diaminoethane (en) solution of (Ge 2 As 2 ) 2− , the heterometallic cluster anion [Au 6 (Ge 3 As)(Ge 2 As 2 ) 3 ] 3− is obtained as its salt [K(crypt‐222)] 3 [Au 6 (Ge 3 As)(Ge 2 As 2 ) 3 ]⋅en⋅2 tol ( 1 ). The anion represents a rare example of a superpolyhedral Zintl cluster, and it comprises the largest number of Au atoms relative to main group (semi)metal atoms in such clusters. The overall supertetrahedral structure is based on a (non‐bonding) octahedron of six Au atoms that is face‐capped by four (Ge x As 4− x ) x − ( x =2, 3) units. The Au atoms bind to four main group atoms in a rectangular manner, and this way hold the four units together to form this unprecedented architecture. The presence of one (Ge 3 As) 3− unit besides three (Ge 2 As 2 ) 2− units as a consequence of an exchange reaction in solution was verified by detailed quantum chemical (DFT) calculations, which ruled out all other compositions besides [Au 6 (Ge 3 As)(Ge 2 As 2 ) 3 ] 3− . Reactions of the heavier homologues (Tt 2 Pn 2 ) 2− (Tt=Sn, Pb; Pn=Sb, Bi) did not yield clusters corresponding to that in 1 , but dimers of ternary nine‐vertex clusters, {[AuTt 5 Pn 3 ] 2 } 4− (in 2 – 4 ; Tt/Pn=Sn/Sb, Sn/Bi, Pb/Sb), since the underlying pseudo ‐tetrahedral units comprising heavier atoms do not tend to undergo the said exchange reactions as readily as (Ge 2 As 2 ) 2− , according to the DFT calculations.