In-situ nitration and syntheses of new Co(II) and Ni(II) complexes assembled from 3-methyl-1-phenyl-5-pyrazolone and cobalt or nickel nitrate under solvothermal conditions

Two new mononuclear complexes, [Co(L−)2(H2O)2] (1) and [Ni(L−)2(H2O)2] (2) (HL = 3-methyl-4-nitro-1-phenyl-5-pyrazolone), have been synthesized by the solvothermal reaction of Co(NO3)2 or Ni(NO3)2 with MPP (MPP = 3-methyl-1-phenyl-5-pyrazolone) in acetonitrile solution, and the ligand HL was generated in-situ through the nitration of MPP mediated by cobalt or nickel nitrate rather than mixture acids. Single crystal X-ray diffraction of 1 reveals that 1 consists of one Co(II), two L− and two coordinated water molecules, and Co(II) adopts slightly octahedral geometry. Through intermolecular hydrogen bonding interactions, 1 presents two-dimensional network. Furthermore, the plausible nitration mechanism of MPP was also discussed.