Cobalt(II) complex containing two-ring scorpionate-like ligands formed in situ. Studies on the [Co0–1-hydroxymethyl-3,5-dimethylpyrazole–MoO3–NH4I] system

We report preparation and characterization of a novel complex cis–mer [Co(L)2]I2 CH3OH (1) (L-N,N-bis(1-(3,5-dimethylpyrazolylmethyl)amine)) isolated from the [Co0–1-hydroxymethyl-3,5-dimethylpyrazole–MoO3–NH4I] system. A two-ring scorpionate ligand (L) was obtained in situ via redox and condensation processes. The catalytical properties of MoO3 are responsible for the formation of this atypical scorpionate ligand. Compound (1) crystallizes in the orthorhombic space group Pna21 with a = 24.5578(14) Å, b = 13.8388(8) Å, c = 9.6072(7) Å, V = 3265.0(4) Å3 and Z = 4. The metal ion coordinates through six nitrogen atoms which belong to two tridentate ligands forming a deformed octahedron. The complex was characterized by IR, FIR, UV–VIS and magnetic investigations. The ligand was ranked in the spectrochemical series between imidazole and bipyridine. The crystal field splitting of tridentate N-donor L was found to be smaller in comparison to e.g. bidentate bipyridine.