Hexameric Silver(I) Pyrazolate: Synthesis, Structure, and Isomerization.

The first binary hexameric silver(I) pyrazolate (Ag6pz6) has been prepared, and X-ray analysis demonstrated that it takes a rare figure-eight shape (pz- = deprotonated tert-butyl 3,5-diphenyl-1H-pyrazole-4-carboxylate). The hexamer can be easily converted to its tetrameric isomer (Ag4pz4) by recrystallization from ether. On the basis of the 1H NMR and mass spectrometry measurements, it is conjectured that the hexamer, after dissolving in CHCl3, quickly achieves equilibrium with Ag4pz4 and Ag3pz3, with the equilibrium lying far to the side of smaller rings.