Tetraaqua(3,4,7,8-tetramethyl-1,10-phenanthroline-kappa2N,N')zinc(II) thiosulfate.

In the title complex of zinc(II) with 3,4,7,8-tetramethyl-1,10-phenanthroline (tmph), viz. [Zn(C16H16N2)(H2O)4](S2O3), the metal atom has a monomeric octahedral ZnN2O4 complex environment comprising two N-atom donors from the tmph group and four aqua O-atom donors. The complex cation is connected to four thiosulfate anions through a compact hydrogen-bonding network involving all coordinated aqua H-atom donors and all the outer acceptors (O and S) of the anion.