Synthesis and characterization of binuclear μ-oxalato nickel(II), copper(II) and zinc(II) complexes with 3,3′-diamino- N-methyl-dipropylamine or trans-1,2-diaminocyclohexane

• Published in: Polyhedron 1999-01, Vol.18 (21), p.2787-2793
• Main Authors: Smékal, Zdeněk, Trávnı́ček, Zdeněk, Lloret, Francesc, Marek, Jaromı́r
• Format: Article
• Language: English
• Subjects: Copper(II) complexes; Crystal structure; Magnetic properties; Nickel(II) complexes; Oxalato-bridged complexes; Zinc(II) complexes
• ISSN: 0277-5387
• DOI: 10.1016/S0277-5387(99)00196-5

New binuclear complexes of the type [(Ni(Medpt)NO 3) 2ox] ( 1) (Medpt=3,3′-diamino- N-methyl-dipropylamine, H 2ox=oxalic acid), [(Ni(dach) 2) 2ox]NO 3·2H 2O ( 2) (dach= trans-1,2-diaminocyclohexane), [(Cu(Medpt)) 2ox]X 2·yH 2O (X=NO 3, y=2 2/3 ( 3); X=ClO 4, y=0 ( 4)) and [(Zn(dach) 2) 2ox](ClO 4) 2·2H 2O ( 5) have been prepared and characterized by IR and UV–Vis spectroscopies. Spectroscopic data are consistent with oxalate-bridged structures between six-coordinated (N 3O 3 or N 4O 2) Ni(II) (compounds 1 or 2), five-coordinated (N 3O 2) Cu(II) (compounds 3 and 4) or six-coordinated (N 4O 2) Zn(II) (compound 5). The crystal structure of [(Cu(Medpt)) 2ox](NO 3) 2·2 2/3 H 2O ( 3) has been determined by single-crystal X-ray analysis. The structure of ( 3) consists of centrosymmetric binuclear cations [(Medpt)Cu(ox)Cu(Medpt)] 2+, nitrate anions and water molecules of crystallization. The copper atom is five-coordinated by two oxalate–oxygen and three Medpt–nitrogen atoms, in a hybrid arrangement between trigonal–bipyramidal and square–pyramidal. The temperature dependence of magnetic susceptibility (1.8–300 K) was measured for compounds 1– 4. Magnetochemical measurements show that Ni(II) complexes are antiferromagnetically coupled, J=−29.4 ( 1) and −32.7 cm −1 ( 2) ( H=− JS 1 S 2) while the Cu(II) complexes present a very weak coupling, J=−2.6 ( 3) and +1.9 cm −1 ( 4), being antiferro- and ferromagnetic in nature.