Mono- and polynuclear Cu(II) coordination compounds that contain diazine ligands

• Published in: Polyhedron 2008-08, Vol.27 (12), p.2650-2654
• Main Authors: Manson, Jamie L., Donovan, Jeffrey, Twamley, Brendan
• Format: Article
• Language: English
• Subjects: Copper; Diazine, coordination polymer; Low-dimensional; Molecular magnet
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2008.05.007

Cu(OTf) 2(2-mepyz) 2(H 2O) 2 ( 1) and Cu(OTf) 2(H 2O) 2(pyz) ( 2) are two new Cu(II) coordination compounds comprised of diazine synthons organized into quasi-2D and 1D structures, respectively. While long-range magnetic ordering was not observed for either compound, significant Cu-pyz-Cu exchange interactions were found in 2. Cu(OTf) 2(2-mepyz) 2(H 2O) 2 (2-mepyz = 2-methylpyrazine; OTf − = CF 3 SO 3 - = triflate), 1, and Cu(OTf) 2(H 2O) 2(pyz) (pyz = pyrazine), 2, consist of monomeric and polymeric structures, respectively. Both compounds contain octahedral Cu(II) metal centers surrounded by trans-coordinated OTf −, H 2O, and diazines, either 2-mepyz in the case of 1 or pyz in 2. In 1, O–H⋯O(triflate) hydrogen bonds link CuO 4N 2 monomers into quasi-1D chains which are joined via O–H⋯N interactions to afford a three-dimensional (3D) network. Pyz ligands in 2 link CuO 4N 2 octahedra into linear chains similar to Cu(NO 3) 2(pyz). Magnetically, neither 1 or 2 show indications for long-range magnetic ordering (LRO) above 2 K. Least-squares fits of the magnetic susceptibility data, χ( T), to a Bonner–Fisher uniform chain model gave 2 J/ k B = −0.005(1) and −6.0(1) K for compounds 1 and 2, respectively, indicative of negligible and moderate antiferromagnetic coupling between spin-1/2 Cu(II) ions. Inter-chain magnetic interactions seem to be negligible for both systems.