Complexation of triangular silver(I) or copper(I) nitropyrazolates with dibenzothiophenes having potential use in adsorptive desulfurization.

Triangular silver(i) and copper(i) 3,5-diethyl-4-nitropyrazolates (abbreviated as [Ag(denpz)]3 or Ag3pz3, and [Cu(denpz)]3 or Cu3pz3), as well as their adducts with dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (DMDBT) and benzothiophene (BT), have been prepared and characterized by a series of techniques. X-ray analyses show that these adducts are stabilized by MS, MC contacts and ππ stacking interactions. NMR measurements and theoretical calculations indicate that the intensity of interaction between the metal complexes and dibenzothiophenes follows the trend: Ag3pz3-DMDBT > Ag3pz3-DBT > Cu3pz3-DMDBT > Cu3pz3-DBT, which can be understood on the basis of a weak interaction between π-acid (Ag3pz3 or Cu3pz3) and π-base (DBT/DMDBT).

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.