Three cobalt (II) complexes with triethylenetetraaminehexaacetic acid: From binuclear complex to 3d-4f coordination polymers

The cobalt(II)–lanthanide(III) heteronuclear complexes [Ln(H2O)4Co2(TTHA)(SCN)2]·H3O+ (H6TTHA = triethylenetetraaminehexaacetic acid, Ln = La(2), Ce(3)) have been synthesized based on a binuclear building block of [Co2(H2TTHA)(H2O)2] in [Co2(H2TTHA)(H2O)2]·4H2O (1). Single-crystal structures show that complex 1 is a binuclear complex, containing the [Co2(H2TTHA)(H2O)2] unit as a useful building block. Adding the La3 + and Ce3 + ions to this synthesis system, two new 3d-4f mixed complexes 2 and 3 were obtained. Complexes 2 and 3 show 3D framework, comprising an infinite 1D (one-dimensional) chain based on heterometallic Ln2Co2 (Ln = La(2), Ce(3)). Further investigations such as IR spectra, UV–vis spectra, TGA, XRD and magnetic properties were studied.