[H 2 bpy] 2 [{Cu(btepy) 2 }Mo 5 P 2 O 23 ]·4H 2 O: A Three‐Dimensional Framework Built from Transition‐Metal Coordination Polymer Sheets Pillared by Polyoxomolybdophosphate Clusters

[H 2 bpy] 2 [{Cu(bpy) 2 }Mo 5 P 2 O 23 ] · 4 H 2 O ( 1 ; bpy = 4,4'‐bipyridine) contains the first three‐dimensional framework based on two‐dimensional transition metal coordination polymer sheets pillared by polyoxomolybdophosphate clusters. It crystallises in the C 2/ c monoclinic space group with a = 17.630(4) Å, b = 13.670(3) Å, c = 25.111(5) Å, and β = 106.61(3)°. Thermogravimetric analysis shows that guest molecules (H 2 O and free bpy ligands) can be easily removed from 1 by simple heat treatment without losing the three‐dimensional framework. Moreover, the paramagnetic properties of the {Cu(bpy) 2 } arrays, make this material an interesting magnetic solid based on polyoxometallate clusters. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)