Transition metal complexes with the thiosemicarbazide-based ligands. Part 12. Synthesis, structure and template reaction of ammine [2,4-pentane-dione S-methylisothiosemicarbazonato(2-)] nickel(II) dihydrate

Summary

Ni(NO₃)₂·6H₂O reacts with 2,4-pentanedione S-methylisothiosemicarbazonehydrogen iodide (H₂L·HI) in aqueous solution; addition of ammonia then yields [NiL(NH₃)]·2H₂O, the crystal structure of which has been determined. In the square-planar [NiL(NH₃)]·2H₂O complex, the ligand, 2,4-pentanedione S-methylisothio-semicarbazone occupies three coordination sites with the bonds to the central atoms involving the terminal nitrogen atoms of the isothiosemicarbazide fragment [Ni−N(3) 1.831 Å and Ni−N(2) 1.842 Å] and the oxygen of the 2,4-pentanedione moiety [Ni−O 1.844 Å]. The template reaction of [NiL(NH₃)]·2H₂O with 2,4-pentanedione and triethyl orthoformate, HC(OEt)₃, gave, by heating the complexes, NiL¹ (1) (L¹ = dianion of the quadridentate NNNN macrocyclic ligand 2,10-bis(methylthio)-5,7,12,14-tetramethyl-1,3,4,8,9,11 -hexaazacyclotetradeca-2,4,6,9,12,-14-hexaene) and NiL² (2) (L² = dianion of the quadridentate ONNO ligand 3-acetyl-6-thiomethyl-9-methyl-5,7,8-tri-azadodeca-3,6,9-triene-2,11-dione) presents described.