Synthesis, structure and magnetic properties of copper(II) chains with anilato-type ligands

Reaction of copper(II) chloride with chloranilic (3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone, H 2 C 6 O 4 Cl 2 ) and bromanilic acid (3,6-dibromo-2,5-dihydroxy-1,4-benzoquinone, H 2 C 6 O 4 Br 2 ) in dimethylformamide (dmf) affords two new anilato-bridged Cu II chains formulated as [Cu(C 6 O 4 Cl 2 )(H 2 O) 2 ]·1.8dmf ( 1 ) and [Cu(C 6 O 4 B 2 )(H 2 O) 2 ]·1.7dmf ( 2 ). Both compounds are isomorphous and crystalise in the monoclinic C 2 /c space group. Their structures consist of linear chains with octahedral Cu II ions bridged by bis-bidentate C 6 O 4 X 2 2− dianions occupying the equatorial positions and two trans water molecules in the axial ones. Compound 2 is the first example of a copper(II) linear chain with bromanilato. Magnetic measurements show that both compounds behave as antiferromagnetic S = ½ regular chains with J = −0.84 (Kitagawa and Kawata, 2002 (1)) and − 3.51 (Benmansour and Gómez-García, 2020a (4)) cm −1 for 1 and 2 , respectively (with a Hamiltonian of the type H = −J S i S i+1 ). The weaker exchange coupling found in 1 can be attributed to the lower electron density in the anilato ring when X = Cl, given the higher electron withdrawing effect of Cl compared with Br.