Synthesis and structure of the first water-soluble chiral monomeric MnIV complex: [Δ-MnIV(biguanide)3] (ClO4)4·H2O

The reaction of KMnO4 with alkaline biguanide sulfate solution, followed by acidification of the resulting stable filtrate with concentrated HClO4, led to the title complex, 1. The crystal structure of the [Δ-MnIV(bigH)3](ClO4)4·H2O (1, bigH: biguanide, C2H7N5) has a tetragonal chiral P41212 space group with a = b = 11.416(3) Å, c = 20.742(7) Å, Z = 4. The complex consists of one chiral [Δ-MnIV(bigH)3] tetracation, four ClO4− anions, and one water molecule. In the tetracation, six N atoms from three neutral biguanide chelate coordinate to the MnIV cation, forming an octahedron with Δ-optical activity. The [Δ-MnIV(bigH)3] tetracation interconnects each other by numerous hydrogen bonds with N–H···O and O–H···O between biguanide moieties of the [Δ-MnIV(bigH)3] tetracations and counter-anions as well as water molecules, to construct a three-dimensional network.