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

The first binary hexameric silver(I) pyrazolate (Agpz) 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 (Agpz) by recrystallization from ether. On the basis of the H NMR and mass spectrometry measurements, it is conjectured that the hexamer, after dissolving in CHCl, quickly achieves equilibrium with Agpz and Agpz, with the equilibrium lying far to the side of smaller rings.