The reactions of K₅Pn₄ (Pn = Sb and Bi) and CpRh(PPh₃)₂ (Cp = C₅H₅, cyclopentadiene) in ethylenediamine (en) solutions resulted in a series of new Pn₇³⁻ adducts, {Pn₈[Rh(PPh₃)]₂}²⁻, {Sb₇[Rh(PPh₃)]₂}²⁻, and {Sb₇[Rh(PPh₃)]₃}²⁻, through slight variations in reaction conditions. These clusters represent rare electron-deficient group 15 polyhedral clusters comprising Pn₇³⁻ with RhPPh₃ units in an η⁵ coordination mode. Notably, the anionic clusters {Sb₈[Rh(PPh₃)]₂}²⁻, {Sb₇[Rh(PPh₃)]₂}²⁻, and {Sb₇[Rh(PPh₃)]₃}²⁻ are the first Rh-Sb binary Zintl clusters to date. The synthesis, structure, and bonding of these new deltahedral hybrids were studied for the first time, revealing a highly versatile chemistry associated with classical Pn₇³⁻ cages and offering a pathway to prepare polyhedral hybrid clusters based on Pn₇³⁻ cages.

In this work, we report the synthesis and characterization of two novel Ru-containing Zintl clusters: [Sn₁₉{Ru(COD)(en)}₂]⁴⁻ and [Sn₂₀{Ru(COD)}₂]⁶⁻. The synthesized compounds not only expand the family of Ru-Sn cluster systems but also shed light on the structure of heterometallic complexes in a previously unknown range of tin atoms. The single-crystal X-ray diffraction (XRD) analysis reveals the dimeric nature of the clusters. Two different assembly patterns of the formal [Sn(η³-Sn₉)] monomer were observed: the dimerization through the vertex fusion process and the direct dimerization through the formation of 2c–2e Sn–Sn σ-bond. For both clusters, the density functional theory calculations reveal the locally σ-aromatic nature of the [Sn(η³-Sn₉)] monomer resulting in two independent magnetic shielding cones. We believe that our findings will help the community to further explore the fascinating chemistry of polystannide clusters.