Capture of [Bi4]6− and [Bi3]5− anions by [Rh(L)]+ (L = COD) cations in the closo heteroatomic clusters {Bi4[Rh(L)]4}2− and {Bi3[Rh(L)]3}2−

Abstract

Compared with the rich chemistry of the lighter polypnictides [Pn_x]^q− (Pn = P, As, Sb, q = charge), our knowledge about the polybismuthides [Bi_x]^q− is still very limited. Here we report two transition metal polybismuthides {Bi₄[Rh(COD)]₄}²⁻ (1) and {Bi₃[Rh(COD)]₃}²⁻ (2), which were isolated by the reaction of the K₅Bi₄/ethylenediamine(en) solutions with 18-crown-6/Rh(COD)(acac) (COD = 1,5-cyclooctadiene, acac = acetylacetonate) and 2,2,2-crypt/Rh(COD)(Cp) (Cp = cyclopentadiene), respectively. Cluster anions 1 and 2 could be viewed as complexes generated from the capture of envelope-like [Bi₄]⁶⁻ and V-type [Bi₃]⁵⁻ anions by the [Rh(COD)]⁺ cation units. Both 1 and 2 are closo (2n + 2) deltahedral structures and have been systematically characterized by single crystal X-ray diffraction (SXRD), energy dispersive X-ray spectroscopy (EDX), electrospray ionization mass spectroscopy (ESI-MS) and NMR (¹H and ¹³C). These findings underline an efficient route to the isolation of novel Zintl anions that are otherwise inaccessible by the introduction of ligated transition metals.