Alternating Ferro/Antiferromagnetic Copper(II) Chain Containing an Unprecedented Triple Formato/Hydroxido/Sulfato Bridge

Abstract

The first example of a triple formato/hydroxido/sulfato (FHS) bridge for any metal is reported in compound [Cu2(bpym)(OH)(HCO2)(SO4)(H2O)2]·3H2O (1). Its structure shows the presence of alternating triple FHS bridges and 2,2'-bipyrimidine (bpym) ones. Although in the initial synthesis the sulfate anions were introduced accidentally, here we report the rational synthesis and the magnetic properties of this compound. The magnetic properties show that 1 is an alternating ferro/antiferromagnetic (F/AF) chain compound with predominant antiferromagnetic interactions and were fit to an alternating F/AF S = (1)/2 chain with g = 2.103, JAF = -139 cm(-1), and JF = 116 cm(-1) (α = JF/|JAF| = 0.83). The JAF value found corresponds very well to those previously reported for Cu-bpym-Cu bridges (average value of ca. -150 cm(-1)). The JF value is also very close to the estimated one (ca. 100 cm(-1)) from magneto-structural correlations in triply Cu-Cu bridged compounds with both hydroxido and carboxylato bridges in equatorial positions.

Noncentrosymmetric Cu(II) Layered Hydroxide: Synthesis, Crystal Structure, Nonlinear Optical, and Magnetic Properties of Cu2(OH)3(C12H25SO4)

“…Given the fact that several exchange pathways exist between two spin carriers, it is here difficult and beyond the scope of this study to perform a clear correlation between the J values determined and the structure of the compound. Yet it is worth noticing that the J values are moderate, and within the usually observed range for Cu–O–Cu (OH, (κ 1 -μ 2 )-sulfate or (κ 1 -μ 2 )-carboxylate bridges) or Cu–OCO-Cu (((κ 1 -κ 1 )-μ 2 )-carboxylate) motives. ,, In particular, it is noteworthy that the Cu–Cu interaction via the ((κ 1 -κ 1 )-μ 2 )-carboxylate ( J 4 ) is ferromagnetic, as expected for a syn – anti carboxylate . Clearly, the peculiar behavior of compound 1 can be explained by the competition between ferromagnetic and antiferromagnetic nearest neighbor exchange interactions.…”

“…Yet it is worth noticing that the J values are moderate, and within the usually observed range for Cu-O-Cu (OH, ( 1 -µ2)-sulfate or ( 1 -µ2)-carboxylate bridges) or Cu-OCO-Cu ((( 1 - 1 )-µ2)-carboxylate) motives. 47,58,59 In particular, it is noteworthy that the Cu-Cu interaction via the (( 1 - 1 )-µ2)-carboxylate (J4) is ferromagnetic, as expected for a syn-anti carboxylate. 60 Clearly, the peculiar behavior of compound 1 can be explained by the competition between ferromagnetic and antiferromagnetic nearest neighbour exchange interactions.…”

Crystal growth, structures and magnetic properties of copper hydroxide compounds with distorted diamond chain magnetic networks

“…The reported values for magnetic paths similar to J 1 and J 3 are in the range of −151.2 to +151.2 cm −1 and +240 to +850 cm −1 , respectively. 19,20 Paths J 4 and J 4 ′, represented by broken lines in Fig. 3a, may be weaker than the others, because the Cu1-O(carboxylate) bond length (2.781(4) Å) is longer than those of the standard axial Cu-O bonds.…”