MOFs by Transformation of 1D-Coordination Polymers: From (1)(infinity)[Ln(BtZ)(3)BtzH] to the Homoleptic Rare Earth 3D-Benzotriazolate Frameworks (3)(infinity)[Ln(Btz)(3)], Ln = La, Ce

The solvent free reaction of rare earth elements with molten 1H-enzotriazole gives 1-dimensional coordiantion polymers of the formula infinity 1[Ln(Btz)(3)(L)]. The ligand L therein is an additional neutral ligand and does not participate in the polymer linkage but saturates the coordination spheres of the lanthanide ions. L can be 1H-benzotriazole (BtzH) and its thermal decomposition products (L = BtzH, Ph(NH2)(2 ()phenylene-diamine, and NH3), (1)(infinity)[Ln(Btz)(3)(BtzH)] transforms upon further heating into homoleptic 3-dimensional networks of the formula (3)(infinity)[Ln(Btz)(3)] under release of neural donor molecules L. For Ln = La and Ce this was proven by a combination of single crystal X-ray diffraction, powder diffraction, thermal and micro analysis. These are the first examples of transformations of 1D-coordination polymers into 3D-framework structures. La and Ce result in isotypic benzotiriazolates. The 3D-frameworks infinity 3[Ln(Btz)(3)] exhibit a cavity system with max diameter of 15 angstrom equalling 18% free space and might therefore also be interesting as porous MOFs.