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

Three new homo- and heterotrimetallic complexes have been synthesized and crystallographically characterized: [Cu2(saldmpn)2(μ-OCH3)2Cu2(hfac)2] (1), [Ni2(valaepy)2(hfac)2] (2), [Cu(saldmpn)Co(hfac)2] (3) [H2saldmpn is the Schiff-base resulting from condensation of salicylaldehyde with 2,2-dimethyl-1,3-diaminopropane and Hvalaepy results from the reaction of o-vanillin with 2-(2-aminoethyl)pyridine)]. The structure of 1 consists of a neutral tetranuclear species that can be viewed as resulting from mutual coordination of one {(hfac)Cu(μ-OCH3)2(Cu(hfac)} and two {Cu(saldmpn)} building blocks. Compound 2 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 3 results from coordination of the [Cu(saldmpn)] metalloligand to cobalt(II) from the {Co(hfac)2} unit. The magnetic properties of 1–3 have been investigated from 1.9 to 300 K. An overall ferromagnetic behavior is observed for 1 and 2 leading to S = 2 low-lying spin state for each one. In the case of 3, 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 Seff = ½ at low temperatures where only the ground Kramers doublet of Co(II) is thermally populated. The values of the intramolecular magnetic couplings in 1–3 are compared with those from the literature on related systems.