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 -[InCl(pzH)]-pzH = pyrazole (pzH), or substituted pyrazoles: 4-Cl-pzH, 4-Br-pzH, 4-I-pzH, 4-Ph-pzH and 3,5-Me-pzH-were synthesized by addition reactions of InCl and pzH and crystallographically characterized. The fluxional behaviour of the complexes, probed by variable temperature 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, /-pyrazole exchange, and N/N tautomerization of the - and of the -pyrazoles. Three novel trianionic hexanuclear complexes of general formula (pipH)[InCl(μ-OH)(μ-OH)(μ-pz)]-pz* = pz, 4-Cl-pz and 4-Ph-pz-showing μ-hydroxo and μ-oxo bridges were synthesized from the corresponding -[InCl(pzH)] and characterized by single crystal X-ray diffraction and H NMR. Under different solvent conditions, multicolour emitting polymeric complexes of general formula [In(μ-pz)]-pz* = pz, 4-Cl-pz, 4-I-pz and 4-Ph-pz-were obtained also from -[InCl(pz*H)] after addition of a base. Luminescence and lifetime calculations were performed for all polymers formed.