From Racemic Compound to Spontaneous Resolution: A Linker‐Imposed Evolution of Chiral [MnMo9O32]6−‐Based Polyoxometalate Compounds

Abstract

Five compounds based on [MnMo(9)O(32)](6-): (Himi)(6)[MnMo(9)O(32)] (1) (imi=imidazole), Na(2)(Himi)(4)[MnMo(9)O(32)]2 H(2)O (2), Na(3)(Himi)(3)[MnMo(9)O(32)] (3), D-NH(4)Mn(2.5)[MnMo(9)O(32)]11 H(2)O (4 a), and L-NH(4)Mn(2.5)[MnMo(9)O(32)]11 H(2)O (4 b) were prepared and characterized. X-ray crystallographic analysis revealed that compounds 1 and 2 with imidazole molecules as linkers are racemic compounds; compound 3 is a racemic solid solution of Na(+) cations and the polyoxoanion [MnMo(9)O(32)](6-); and compounds 4 a and 4 b are enantiomers. In compound 4, the homochiral polyoxoanions [MnMo(9)O(32)](6-) are connected by Mn(2+) cations to form a unique (4(5)6)(4(7)6(8)) topology net framework. By adjusting the linkers from imidazole molecules to Na(+) and finally Mn(2+) cations, the chiral polyoxoanions [MnMo(9)O(32)](6-) were changed from a racemic compound to a conglomerate. This means that spontaneous resolution can be efficiently realized by connecting homochiral polyoxoanions into one-dimensional (1D), 2D, and 3D structures, with an emphasis on using appropriate linkers with substantial interaction strength, directionality, and enantioselectivity.