Synthesis, crystal structure and magnetic properties of a novel copper(II) complex with sulfoisophthalic acid

A new Cu(II) complex, [Cu2(μ2-OH2)2(HSIP)2(H2O)6] (H3SIP = 5-sulfoisophthalic acid), has been synthesized and characterized by single crystal X-ray diffraction, EPR spectroscopy (X- (9.5 GHz) and Q-band (35 GHz)) and magnetic measurements. The solid state structure of the complex consists of coordination dimers [Cu2(μ2-OH2)2(HSIP)2(H2O)6] which are hydrogen bonded into 3D network. The neighbouring metal ions form a rare example of centrosymetric dinuclear core [Cu2(μ2-OH2)2] with equatorial – axial positions of the bridging ligands. The coordination dimers are organized into inorganic monolayers via water–sulfonate hydrogen bond intractions, and further linked in 3D structure via carboxylic–carboxylic hydrogen bond intractions. The magnetic properties and EPR spectra are discussed in terms of crystal structure features. The X- and Q-band EPR spectra exhibit fine structure signals due to S = 1 and the simulated parameters indicate small zero field splitting parameter Dexp (−0.035 cm−1) dominated by Ddip (−0.031 cm−1). A usually forbidden ΔMs = 2 line of lower intensity is observed in the half field region at about 150 mT. The susceptibility data have been analyzed using a spin–ladder model with both ferromagnetic (rungs) and antiferromagnetic (legs) coupling.