3.2.4. Synthesis of [NH4]2{CuMo6O16(OH)2[HOCH2C(CH2O)3]2}·4H2O (**4**)

The synthetic procedure of compound **4** was similar with that of compound **3** except that the pH of the solution was adjusted to 2. Elemental analysis calcd. (%) for [NH4]2{CuMo6O16(OH)2[HOCH2C(CH2O)3]2}·4H2O (Mw = 1303.59 g mol<sup>−</sup>1): C 9.21%, H 2.78%, N 2.15%, Cu 4.87%, and Mo 44.16%; found C 9.28%, H 2.87%, N 2.22%, Cu 4.90%, and Mo 44.21%.
