Formation of [K(18‐crown‐6)]2Bi2 and the influence of 18‐crown‐6 on the crystallization of bismuth‐based Zintl clusters obtained from Bi22−

Abstract

AbstractSo far, homoatomic polybismuthide Zintl anions, which can be used as starting materials for larger binary or ternary, bismuth‐based clusters, have always been isolated from potassium‐based Zintl phases using 4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane (crypt‐222) to sequester the K+ counterions. The formation of larger clusters from such anions is still poorly understood, and a change of the sequestering agent might lead to the crystallization of missing links in the cluster formation pathways, which is why – in addition to cost considerations – such variants are being investigated. Herein, we present the synthesis and characterization of the first homoatomic polybismuthide salt with a 1,4,7,10,13,16‐hexaoxacyclooctadecane (18‐crown‐6) complex as counterion, [K(18‐crown‐6)]2Bi2 (1). By means of mass spectrometry, we show that compound 1 behaves, generally, alike [K(crypt‐222)]2Bi2 in reactions with [CpRu(NCMe)3]+, forming the previously reported cluster anion [{CpRu}3Bi6]−. However, crystallization of this cluster can only be achieved in the presence of [PF6]− anions, yielding [{K(18‐crown‐6)}2{PF6}][{CpRu}3Bi6] ⋅ en (2). This shows that [K(18‐crown‐6)]+, if paired up with an additive like [PF6]−, indeed is a (cheaper) alternative for the crystallization of anionic bismuth‐based clusters.