[(K,Rb)@([2.2.2]crypt)]₂(K,Rb)₄[Si₉W(CO)₄] ⋅ 13.4 NH₃ – The First Tungsten Functionalized Silicon Zintl Cluster

Abstract The reaction between the heteroleptic metal carbonyl complex [W(CO) 4 (tmeda)] ((tmeda)= N , N , N ′, N ′‐Tetramethylethane‐1,2‐diamine) with [Si 9 ] 4− silicon Zintl clusters in presence of [2.2.2]crypt ([2.2.2]crypt=4,7,13,16,21,24‐Hexaoxa‐1,10‐diazabicyclo[8.8.8]‐hexacosane) in liquid ammonia yielded the compound [(K,Rb)@([2.2.2]crypt)] 2 (K,Rb) 4 [Si 9 W(CO) 4 ] ⋅ 13.4 NH 3 . The compound was analyzed by single crystal X‐ray diffraction and crystallizes in the space group ( a =11.48390(10) Å, b =19.7383(2) Å, c =19.8983(2) Å, α =112.5760(10)°, β =97.4210(10)°, γ =95.3760(10)°, V =4079.01(7) Å 3 ). The compound represents the first group 6 carbonylate‐functionalized silicon Zintl cluster. The central moiety is composed of a tricapped trigonal prismatic nine‐atom silicon species which coordinates with the lone pair of one capping atom to the tungsten tetracarbonylate, forming a pseudo trigonal bipyramidal carbonylate cluster anion [Si 9 W(CO) 4 ] 6− . The chemical bonding in the new cluster entity is analyzed using theoretical calculations and subsequent analysis using QTAIM and NBO.