A 36-Nuclear Wheel-Shaped Heterometallic Cluster: Self-Assembly of Mixed-Valent Pt ^II /Pt ^IV and Mn ^II Centers

Polynuclear 5d–3d assemblies represent a promising class of systems for exploring the interplay among electronic structure, magnetism, and self-assembly. Here, we report the synthesis and structural characterization of the first heterometallic wheel-shaped Pt–Mn cluster, [PtIV12PtII6Mn18(OAc)72(μ3-O)12]·43C6H6 (1), which incorporates 36 metal centers. The giant ring is constructed from alternating PtIIMnII paddlewheel fragments and PtIV2Mn2 oxo-acetate units, bridged by μ3-oxo and carboxylate ligands, resulting in a cyclic motif unprecedented for 5d–3d systems. The coexistence of PtII and PtIV centers, originating from partial reduction of PtIV precursors, is crucial for directing the wheel topology. Reactivity studies with 1,10-phenanthroline afforded discrete binuclear [PtIIMn(μ2-OAc)4(phen)]·MeCN (2) and tetranuclear [Pt2IVMn2(μ3-O)2(μ2-OAc)8(phen)2]·3MeCN (3) derivatives, confirming that the wheel can fragment into stable subunits upon ligand binding. Magnetic studies reveal weak antiferromagnetic interactions within Mn3 triangular motifs, consistent with structural analysis and carboxylate-bridging modes. Preliminary density functional theory calculations show that the self-assembly of (1) is thermodynamically favorable (ΔG = −61.42 kcal/mol), supporting the proposed assembly pathway. This study extends the chemistry of wheel-shaped polynuclear complexes to the 5d-3d domain, illustrating how mixed-valent platinum centers can promote the formation of unprecedented architectures.