TRANSITION-METAL COMPLEXES WITH THE THIOSEMICARBAZIDE-BASED LIGANDS .12. SYNTHESIS, STRUCTURE AND TEMPLATE REACTION OF AMMINE [2,4-PENTANE-DIONE S-METHYLISOTHIOSEMICARBAZONATO(2-)] NICKEL(II) DIHYDRATE

Ni(NO3)2-6H2O reacts with 2,4-pentanedione S-methylisothiosemicarbazonehydrogen iodide (H-2L.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-methylisothiosemicarbazone 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 angstrom and Ni-N(2) 1.842 angstrom] and the oxygen of the 2,4-pentanedione moiety [Ni-O 1.844 angstrom]. 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.