Binding of a TlCl Entity by a Tetragold Tetramercaptothiacalixarene Metalloligand via Metallophilic Interactions

The successive auration of p‐tert‐butyltetramercaptotetrathiacalix[4]arene, H(4)(MTC[4]), with gold(I) phosphine units was investigated. Through deprotonation with NaOMe, followed by salt metathesis reactions with (PR(3))AuCl (R=Me, Ph) complexes with two and three [(PR(3))Au](+) moieties could be prepared and isolated, namely [(Ph(3)PAu)(2)H(2)(MTC[4])] and [(Me(3)PAu)(3)H(MTC[4])]. In [(Me(3)PAu)(3)H(MTC[4])] two gold atoms already come close enough to undergo aurophilic interactions. To introduce a fourth [(PR(3))Au](+) entity TlOEt had to be used for the deprotonation, which led to the finding that four gold atoms organised by the (MTC[4])(4−) coordination platform are able to bind and stabilize a TlCl entity, yielding [(Me(3)PAu)(4)TlCl(MTC[4])]. As evidenced by structural and theoretical investigations the binding occurs through strong metallophilic interactions, which lead to photoluminescence at low temperatures