Synthesis, structure, DFT calculation and ring-opening polymerization of manganese and iron complexes incorporating bidentate pyrazolyl precursor

Two new manganese and iron complexes, namely [{C₃H₃N₂(CH₂)₂}N{C₆H₃(CHMe₂)₂–2,6}]MnCl₂·0.5(C₄H₈O) (1) and [{C₃H₃N₂(CH₂)₂}N{C₆H₃(CHMe₂)₂–2,6}]FeCl₂·0.5(C₄H₈O) (2) were synthesized by the reaction of a pyrazolyl ligand, [2,6-diisopropylphenyl]-bis[(1-H-pyrazol-1-yl)methyl] amine with MnCl₂ and FeCl₂, respectively in THF as satisfactory yield. The pyrazolyl ligand coordinates as a bidentate fashion through its pyrazole N-donor sites to the metal center. Single crystal X-ray structural analysis reveals that in both metal complexes, the central metal ion possess on a distorted tetrahedral environment consisting a eight-membered chelate ring. The DFT (Density functional theory) calculation is governed getting an insight about the different possible configurations of electron spins among two metal derivatives. In a well-controlled approach, both the manganese and iron compounds reveal adequate reactivity in the ring-opening polymerization (ROP) of L-lactide and ε-caprolactone in dichloromethane.