Novel Example of a Chain Structure Formed by 1,4-Dioxane and Cobalt(II) Links. Chain [Co₃(μ-OOCCF₃)₄(μ-H₂O)₂(OOCCF₃)₂(H₂O)₂(C₄H₈O₂)]·2C₄H₈O₂

Abstract

The trimer [Co3(mu-OOCCF3)4(mu-H2O)2(OOCCF3)2(H2O)2(C4H8O2)].2C4H8O2. (1) is composed of three tetragonally distorted Co(II) centers bridged by four trifluoroacetates and two bridging water molecules. 1,4-Dioxane is coordinated at a distance of 2.120(3) A from the terminal cobalt Co2; the remaining oxygen of this 1,4-dioxane links the terminal cobalt to a neighbor trimer, forming a one-dimensional chain. The crystal structure displays a network of hydrogen bonds between four noncoordinated 1,4-dioxane molecules and the coordinated terminal water molecules. The magnetic properties of 1 were analyzed with the use of the Hamiltonian including isotropic exchange interactions between real spins of a high-spin Co(II), spin-orbit coupling and a low-symmetry crystal field acting within the (4)T(1g) ground manifold of each cobalt ion. A weak antiferromagnetic exchange interaction between cobalt ions in 1 was found. The results of the magnetic model are in good agreement with the experimental observations.

Exchange-Coupled Cobalt(II) Dimer with Unusual Magnetic Circular Dichroism Saturation Behavior

“…As can be seen, a good agreement is obtained between the experimental data and theoretical modeling. A small negative value of the anisotropic exchange parameter is typical for the cobalt(II) complexes, where magnetic exchange takes place through the bridging water and carboxylate groups. , The obtained value of the orbital reduction factor lies between the limits for the weak and strong crystal fields and is also typical for high-spin cobalt(II) complexes . A relatively large negative value of the Δ parameter indicates that distortion of the octahedral surroundings corresponds to compression along the symmetry axis.…”

Magnetic metal–organic frameworks

“…suggests that J is weakly antiferromagnetic. 135 For the similar trimer Co 3 (PhCOO) 6 (py) 2 (Fig. 3 (I)) no magnetic data are given.…”

High-spin Co(II) in monomeric and exchange coupled oligomeric structures: Magnetic and magnetic circular dichroism investigations

“…The linear trimer (8) is composed of three tetragonally distorted Co(II) centers bridged by four trifluoroacetate groups and two bridging water molecules [53] (see Fig. 16).…”

“…Theoretical curve is calculated at Jex = −0.4 cm −1 , Ä1 = 0.77, Ä2 = Ä3 = 0.72, 1 = −970 cm −1 , 2 = 3 = −1160 cm −1 .Figure wasreproduced from Ref [53],. with permission of the copyright holders.…”