Synthesis and Characterisation of the First Three‐Dimensional Mixed‐Metal‐Center Inorganic‐Organic Hybrid Framework with N ‐(Phosphonomethyl)iminodiacetate

Using crystal engineering concepts, the first three‐dimensional (3D) mixed‐metal‐centre inorganic‐organic hybrid frameworks incorporating N ‐(phosphonomethyl)iminodiacetate (pmida 4− ) were synthesised under mild hydrothermal conditions (100 °C) and characterised structurally. The crystal structures, obtained by the displacement of the coordinated water molecules in [Co 2 V 2 O 2 (pmida) 2 (H 2 O) 10 ]·2(H 2 O) ( 1 ) [ P 2 1 / c monoclinic space group, Z = 2, a = 9.996(2) Å, b = 14.854(3) Å, c = 10.781(2) Å, β  = 110.90(3)° and V = 1495.5(5) Å 3 ] by the rod‐like bridging 4,4′‐bipyridine (4,4′‐bpy) ligand — [CdVO(pmida)(4,4′‐bpy)(H 2 O) 2 ]·(4,4′‐bpy) 0.5 ·H 2 O ( 2 ) and [CoVO(pmida)(4,4′‐bpy)(H 2 O) 2 ]·(4,4′‐bpy) 0.5 ( 3 ) — are isostructural and were also determined in the P 2 1 / c monoclinic space group ( Z  = 4) by single‐crystal X‐ray diffraction studies at low temperature (180 K): for 2 , a = 9.1267(18) Å, b = 17.610(4) Å, c = 15.361(3) Å, β  = 93.06(3)° and V = 2465.3(9) Å 3 ; for 3 , a = 8.7734(18) Å, b = 17.264(4) Å, c = 15.507(3) Å, β  = 93.94(3)° and V = 2343.2(8) Å 3 . All the crystal structures contain centrosymmetric dimeric [V 2 O 2 (pmida) 2 ] 4− units connected to neighbouring M 2+ cations (Cd 2+ for 2 , and Co 2+ for 1 and 3 ) through the phosphonate group. In 2 and 3 , extended two‐dimensional [MVO(pmida)(H 2 O) 2 ] n layers are formed, with the 4,4′‐bpy molecules acting as pillars between adjacent layers, leading to porous 3D supramolecular structures, [MVO(pmida)(4,4′‐bpy)(H 2 O) 2 ] ∞ , with a topology resembling that of the NbO net. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)