Ligand metathesis, Co(II) coordination, and partial condensation reactions of an archetypal {Zr 6 } zirconium oxocarboxylate cluster result in the first example of the coexistence of the distinct zirconium oxide frameworks {Zr 6 O 8 } and {Zr 12 O 22 }. Even minor modifications to the reaction conditions push this apparent equilibrium towards the {Zr 6 O 8 }-based product.

Five novel one-dimensional cerium(III) carboxylate coordination polymers, [Ce(O 2 CCH 2 CHMe 2•2Me 2 CHCO 2 H} n (5), showcase the surprisingly consistent tendency of Ce(III) coordination network structures to adopt one-dimensional connection modes. The type of carboxylate as well as the reaction solvents determines the exact bridging versus end-on coordination modes for the carboxylates and, in turn, discriminate between linear, zigzag, and helical arrangements. Detailed magnetochemical analyses reveal pronounced single-ion effects and the expected weak antiferromagnetic coupling.

On the way to copper(I) iodide coordination polymers with specific luminescent properties, the in situ reduction of Cu(II) in the presence of KI and bidentate N-heteroatomic ligand, either pyrazine (pyz) or 4,4'-bipyridine (bpy), resulted in one two-dimensional and two three-dimensional new coordination networks. Starting from Cu(NO)·3HO in the presence of pyz, successive precipitation of known yellow [(CuI)(pyz)], new orange [CuI(pyz)], and new dark blue {[Cu(pyz)]·I} polymeric solids was observed. Starting from the same salt in the presence of bpy resulted in the successive precipitation of known yellow [(CuI)(bpy)] and new brown {[Cu(NO)(bpy)]·I·(dmf·HO)} coordination polymers. By using either Cu(CHCOO)·HO or Cu(BF) as starting materials, both known forms, yellow [(CuI)(bpy)] and orange [CuI(bpy)], precipitated successively. The new solids were characterized by IR spectroscopy and X-ray analysis. [CuI(pyz)] represents the missing member in the row of two-dimensional coordination networks with general formula [CuX(pyz)] (X = Cl, Br, I). Its steady state and time-resolved characterization together with DFT and TDDFT calculations revealed that the emission at room temperature is mainly delayed fluorescence originating from mixed singlet metal-to-ligand charge transfer and halide-to-ligand charge transfer states, while that at 77 K is phosphorescence, associated with the small singlet-triplet energy differences (ΔE = 70 meV).

Small changes to the reaction conditions differentiate between two metal–organic frameworks (MOFs), {[Ce2(H2O)(bpdc)3(dmf)2]·2(dmf)} n (1) and {[Ce4(H2O)5(bpdc)6(dmf)]·x(dmf)} n (2), that were solvothermally synthesized from cerium(III) nitrate hexahydrate and 2,2′-bipyridine-5,5′-dicarboxylic acid (H2bpdc) in dimethylformamide (dmf). The two compounds illustrate how the flexibility of the coordination geometry of CeIII translates into MOFs, the formation of which readily adapts to different solvent environments.