Homo- and heterometallic complexes constructed from hexafluoroacetylacetonato and Schiff-base complexes as building-blocks

<p>Three new homo- and heterotrimetallic complexes have been synthesized and crystallographically characterized: [Cu<sub>2</sub>(saldmpn)<sub>2</sub>(<i>μ</i>-OCH<sub>3</sub>)<sub>2</sub>Cu<sub>2</sub>(hfac)<sub>2</sub>] (<b>1</b>), [Ni<sub>2</sub>(valaepy)<sub>2</sub>(hfac)<sub>2</sub>] (<b>2</b>), [Cu(saldmpn)Co(hfac)<sub>2</sub>] (<b>3</b>) [H<sub>2</sub>saldmpn is the Schiff-base resulting from condensation of salicylaldehyde with 2,2-dimethyl-1,3-diaminopropane and Hvalaepy results from the reaction of <i>o</i>-vanillin with 2-(2-aminoethyl)pyridine)]. The structure of <b>1</b> consists of a neutral tetranuclear species that can be viewed as resulting from mutual coordination of one {(hfac)Cu(<i>μ</i>-OCH<sub>3</sub>)<sub>2</sub>(Cu(hfac)} and two {Cu(saldmpn)} building blocks. Compound <b>2</b> is a binuclear complex that results from two {Ni(hfac)(valaepy} fragments, the nickel(II) ions bridged by the two phenoxide-oxygens. The heterobinuclear complex <b>3</b> results from coordination of the [Cu(saldmpn)] metalloligand to cobalt(II) from the {Co(hfac)<sub>2</sub>} unit. The magnetic properties of <b>1–3</b> have been investigated from 1.9 to 300 K. An overall ferromagnetic behavior is observed for <b>1</b> and <b>2</b> leading to <i>S</i> = 2 low-lying spin state for each one. In the case of <b>3</b>, a non-magnetic ground state results because of the occurrence of an intramolecular antiferromagnetic coupling between the copper(II) ion and the high-spin cobalt(II) ion, this last one behaving as an effective spin <i>S</i><sub>eff</sub> = ½ at low temperatures where only the ground Kramers doublet of Co(II) is thermally populated. The values of the intramolecular magnetic couplings in <b>1–3</b> are compared with those from the literature on related systems.</p>