Synthesis, crystal structure and magnetic properties of catena-poly[(2,2′-bipyridylcopper)-di-μ-thiocyanato] and bis(2,2′-bipyridyl)thiocyanatocopper(II) perchlorate

Abstract

The reaction of ethanolic solutions of CuX 2 (X=NO 3 −, ClO 4 −), with bidentate amine, 2,2′-bipyridyl (bipy) and ammonium thiocyanate, leads to the high-yield formation of { catena-[Cu(bipy)(μ N,S-NCS) 2]} ( 1) and [Cu(NCS)(bipy) 2]ClO 4 · 1/2CH 3CN ( 2). The crystal structure of 1 and 2 were determined. Complex 1 crystallises in the monoclinic system, space group C2/ c with a=8.125(4) Å, b=15.557(6) Å, c=10.536(3) Å, β=95.32(3)° and Z=4. The crystal structure consists of neutral Cu(NCS) 2(bipy) units which are bridged by sulfur atoms of the thiocyanate groups to yield a 1D chain. Complex 2 crystallises in the monoclinic system, space group C2/ c with a=12.694(4) Å, b=25.007(11) Å, c=15.479(11) Å, β=106.85(4)° and Z=8. The crystal structure consists of a [Cu(NCS)(bipy) 2] + cation, ClO 4 − anion and CH 3CN. The cations show a quasi-trigonal bipyramidal coordination. A variable temperature magnetic susceptibility study was performed on 1 at a temperature range of 2–300 K. The compound shows a very weak antiferromagnetic coupling ( J=−0.13 cm −1) and the magnetic susceptibility data were analysed by the expression for the magnetic susceptibility of isotropically coupled S=1/2 ions in antiferromagnetic chains. The single crystal EPR spectra of 2 presents rhombic g values and the direction of the highest g value lies in the equatorial plane near the Cu–N eq direction; therefore, this is a distorted trigonal bipyramidal structure.