Antimony tartrate transition-metal-oxo chiral clusters.

A chiral precursor K2Sb2(L-tartrate)2 was used for the assembly of three homochiral heterometallic antimony(III)-tartrate transition-metal-oxo clusters: Mn(H2O)6[Fe4Mn4Sb6(μ4-O)6(μ3-O)2(l-tartrate)6(H2O)8]·10.5H2O (1), [V4Mn5Sb6(μ4-O)6(μ3-O)2(L-tartrate)6(H2O)13]·9.5H2O (2), and (H3O)[Ni(H2O)6]2[NiCrSb12(μ3-O)8(μ4-O)3(l-tartrate)6]·6H2O (3). In 1 and 2, the antimony tartrate dimer precursor decomposes and recombines to form Sb3(μ3-O)(L-tartrate)3 chiral trimers, which act as scaffolds to construct negative-charged [Fe4Mn4Sb6(μ4-O)6(μ3-O)2(L-tartrate)6](2-) in 1 and neutral [V4Mn5Sb6(μ4-O)6(μ3-O)2(L-tartrate)6] in 2. The scaffold is flexible and accommodates different types of transition-metal-oxo clusters due to the different possible coordination modes of the L-tartrate ligand. In 3, a two-level chiral scaffold Sb3(μ3-O)(L-tartrate)3Sb3 is formed from the precursor. Two such scaffolds are linked by three bridging oxygen atoms to form a cavity occupied by one Cr(3+) ion and one Ni(2+) ion disordered over two positions. Cr(3+) and Ni(2+) ions are located in two face-shared MO6 octahedra at the center of a negatively charged [NiCrSb12(μ3-O)8(μ4-O)3(L-tartrate)6](3-) cluster.