In situ imidazolate?4,5?diamide?2?olate (L2) linker generation under conventional electrical (CE) heating and microwave (MW)?assisted conditions leads to the formation of the porous three?dimensional hydrogen?bonded molecular building block (MBB) [Cd14(L2)12(O)(OH)2(H2O)4(DMF)4] based network, named as HIF?3. In the MBB a Cd6 octahedron is inscribed in a Cd8 cube. The evacuated materials show good N2, CO2, and H2 gas sorption, in comparison with other H?bonded networks. The desorption branches exhibit a broad hysteresis, suggesting that the materials show flexible behavior during gas uptake. Positron annihilation lifetime spectroscopy (PALS) shows inherent crystal defects of the materials. PALS indicates that the contribution of mesopores (10 and 14?% for HIF?3?CE and ?MW, respectively) due to missing building blocks, makes the frameworks structurally flexible.