Synthesis and characterization of a series of diphenyldipyrazolylmethane complexes with zinc(II)

The zinc(II) coordination chemistry of a series of diphenyldipyrazolylmethane ligands was explored using 1H NMR and single crystal X-ray diffraction. Unsubstituted diphenyldipyrazolylmethane (dpdpm), diphenylbis(3-methylpyrazolyl)methane (dpdp′m), and diphenylbis(3,5-dimethylpyrazolyl)methane (dpdp″m) were reacted with Zn(NO3)2 to afford Zn(dpdpm)(NO3)2, Zn(dpdp′m)(NO3)2 and Zn(Pz″)2(NO3)2 where Pz″ = 3,5-dimethylpyrazole, respectively. All attempts to isolate Zn(dpdp″m)(NO3)2 with the intact dpdp″m ligand were unsuccessful due to decomposition of the ligand. These bidentate ligands support the formation of 1:1 ligand to metal complexes and structurally model the two histidine coordination mode common in zinc proteins.