2.2.1. [Cd(phen)(en)]2[Cd2(phen)2V12O40Ge8(OH)8(H2O)]·12.5H2O (**1**)

V2O5 (0.061 g, 0.33 mmol), GeO2 (0.069 g, 0.67 mmol) and TMAH (TMAH = tetramethylammonium hydroxide) (0.10 mL) were added to H2O (3.00 mL) solution with stirring for a half-hour. Then, CdCl2 (0.061 g, 0.33 mmol), phen (0.066 g, 0.33 mmol) and 2,2 -bpy (2,2 bpy = 2,2 -bipyridine, 0.052 g, 0.33 mmol) were added, the resulting suspension was further stirred for 4 h, the pH of the mixture was 5.0. Finally, the pH of the mixture was adjusted to 9.5 with en, which was stirred for another 0.5 h and then was sealed in a Teflon-lined stainless bomb and heated at 170 ◦C for 5 days. Brown rectangle crystals were collected by filtration and washed with water (Yield: 0.149 g, 51.60% based on GeO2). Compound **1** can also be prepared by adjusting the pH to 10.0. When the pH of the mixture was adjusted to 9.5, more crystals were obtained, and the crystal quality was better. Anal. Calcd for C52H83Cd4Ge8N12O61.5V12: C, 17.83; H, 2.39; N, 4.80%. Found: C, 17.71; H, 2.28; N, 4.83%.
