New nickel(II) and palladium(II) complexes with unsymmetrical quadridentate Schiff bases derived from 8-amino-4-methyl-5-azaoct-3-en-2-one. Crystal and molecular structure of [4,10-dimethyl-3-(nitroso-χN)-5,9-(diaza-χ2N)-trideca-3,10-diene-2,12-(dionato-χO)(2–)]nickel(II)

Abstract

A monocondensation product of pentane-2,4-dione and 1,3-diaminopropane, 8-amino-4-methyl-5-azaoct-3-en-2-one, has been used as a precursor in preparation of three new unsymmetrical quadridentate Schiff-base ligands comprising a trimethylenedi-imine moiety. Nickel(II) and palladium(II) complexes of these ligands have been obtained and characterized by spectroscopic techniques. They are of essentially square-planar geometry and diamagnetic. The single-crystal structure of (4,10-dimethyl-3-nitroso-5,9-diazatrideca-3,10-diene-2,12-dionato)nickel(II) has been determined and shows the co-ordination of nickel by a nitroso group through the nitrogen atom. Crystallographic data: space group P2₁/c(no. 14), a= 8.788(2), b= 7.562(2), c= 21.502(8)Å, β= 98.49(2)°, final R and R′ 0.0422 and 0.0490, respectively.