- New Compounds Bearing [M(S2O7)(3)](2-) Anions (M=Si, Ge, Sn): Syntheses and Characterization of A(2)[Si(S2O7)(3)] (A=Na, K, Rb), A(2)[Ge(S2O7)(3)] (A=Li, Na, K, Rb, Cs), A(2)[Sn(S2O7)(3)] (A=Na, K), and the Unique Germanate Hg-2[Ge(S2O7)(3)]Cl-2 with Cationic 1 infinity[HgCl2/2](+) Chains