Homometallic {Mn₁₀} and heterometallic {Mn₆Ca₄} supertetrahedra exhibiting an unprecedented {Mn^III₉Mn^II} oxidation state level and heterometal ions distribution

Two novel decametallic clusters displaying a supertetrahedral structural core are discussed, a homometallic compound [Mn^III₉Mn^II(μ₄-O)₄(μ₃-OMe)₃(btH)₃(ed)₃(PhCO₂)₆]·6Η₂Ο (1·6Η₂Ο) (btH₃ = (±)-1,2,4-butanetriol; edH₂ = 1,2-ethanediol) and a heterometallic one [Mn^III₆Ca^II₄(μ₄-O)₄(μ₃-Cl)₄(pd)₆Cl₂(MeOH)₁₀] (2) (pdH₂ = 1,3-propanediol). In particular complex 1·6Η₂Ο is a new member of an extended family of homometallic Mn₁₀ supertetrahedra which exhibits an unprecedented Mn^III₉Mn^II oxidation state level. It is based on a supertetrahedral [Mn^III₉Mn^II(μ₄-O)₄]²¹⁺ core with its peripheral ligation being completed by bridging alkoxy (OMe⁻, btH²⁻, ed²⁻) and carboxylate (PhCO₂⁻) ligands. Complex 2 is a unique heterometallic analogue of the family of complexes displaying the well-known [Mn^III₆Mn^II₄(μ₄-O)₄]¹⁸⁺ supertetrahedral core in which the Mn^II ions have been replaced by Ca^II ions. The peripheral ligation of the heterometallic [Mn^III₆Ca^II₄(μ₄-O)₄]¹⁸⁺ core is completed by both bridging (μ₃-Cl⁻ and pd) and terminal (Cl⁻, MeOH) ligands. Magnetism studies revealed that complex 1·6Η₂Ο displays dominant ferromagnetic exchange interactions and a large spin ground state value S_T = 23/2 whereas complex 2 exhibits exclusively ferromagnetic exchange interactions and the maximum possible spin ground state S_T = 12 for a complex consisting of six Mn^III and four Ca^II ions.