CuII acetate complexes involving N,N,O donor Schiff base ligands: Mono-atomic oxygen bridged dimers and alternating chains of the dimers and Cu2(OAc)4

Two tridentate N,N,O donor Schiff bases, HL1 (4-(2-ethylamino-ethylimino)-pentan-2-one) and HL2 (3-(2-amino-propylimino)-1-phenyl-butan-1-one) on reaction with CuII acetate in presence of triethyl amine yielded two basal-apical, mono-atomic acetate oxygen-bridging dimeric copper(II) complexes, [Cu2L12(OAc)2] (1), [Cu2L22(OAc)2] (2). Whereas two other similar tridentate ligands HL3 (4-(2-amino-propylimino)-pentane-2-one) and HL4 (3-(2-amino-ethylimino)-1-phenyl-butan-1-one) under the same conditions produced a mixture of the corresponding dimers and a one-dimensional alternating chain of the dimer and copper acetate moiety, [Cu4L32(OAc)6]n (3) and [Cu4L42(OAc)6]n (4), formed by a very rare μ3 bridging mode of the acetate ion. All four complexes (1–4) have been characterized by X-ray crystallography. The isotropic Hamiltonian, H = −JS1S2 has been used to interpret the magnetic data. Magnetic measurements of 1 and 2 in the temperature range 2–300 K reveal a very weak antiferromagnetic coupling for both complexes (J = −0.56 and −1.19 cm−1 for 1 and 2, respectively).

Graphical abstractTwo N,N,O donor Schiff bases, yielded basal-apical, mono-atomic acetate oxygen bridging dimeric copper(II) complexes. Whereas two other similar tridentate ligands produced a mixture of the corresponding dimers and a one-dimensional alternating chain of the dimer and copper acetate moiety, formed by a very rare μ3 bridging mode of the acetate ion. Variable temperature magnetic measurements of the dimers reveal a very weak antiferromagnetic coupling.Figure optionsDownload full-size imageDownload as PowerPoint slide