Mononuclear, hexanuclear and polymeric indium(III) pyrazolido complexes; structural characterization, dynamic solution studies and luminescent properties.

A new family of six mononuclear indium(III) complexes of formula mer -[In III Cl 3 (pz*H) 3 ]-pz*H = pyrazole (pzH), or substituted pyrazoles: 4-Cl-pzH, 4-Br-pzH, 4-I-pzH, 4-Ph-pzH and 3,5-Me 2 -pzH-were synthesized by addition reactions of InCl 3 and pz*H and crystallographically characterized. The fluxional behaviour of the complexes, probed by variable temperature 1 H NMR spectroscopy in the 328 K to 173 K range, was attributed to (at least) four simultaneous processes: pyrazole N-H proton dissociation/association, cis / trans -pyrazole exchange, and N 1 /N 2 tautomerization of the cis - and of the trans -pyrazoles. Three novel trianionic hexanuclear complexes of general formula (pipH) 3 [In 6 Cl 6 (μ 3 -OH 0.5 ) 2 (μ-OH) 6 (μ-pz*) 6 ]-pz* = pz, 4-Cl-pz and 4-Ph-pz-showing μ-hydroxo and μ-oxo bridges were synthesized from the corresponding mer -[In III Cl 3 (pz*H) 3 ] and characterized by single crystal X-ray diffraction and 1 H NMR. Under different solvent conditions, multicolour emitting polymeric complexes of general formula [In(μ-pz*) 3 ] n -pz* = pz, 4-Cl-pz, 4-I-pz and 4-Ph-pz-were obtained also from mer -[In III Cl 3 (pz*H) 3 ] after addition of a base. Luminescence and lifetime calculations were performed for all polymers formed.