Investigation of the CuII/NCS−/dpk Reaction System in CH3OH [dpk = Di(2-pyridyl) Ketone]: Isolation, Structural Analysis and Magnetic Properties of a Dimer and a 1D Polymer with the Same Empirical Formula [Cu(NCS)2(dpk·CH3OH)]

Two polymorphous compounds with the general formula [Cu(NCS)2(dpk·CH3OH)]n (dpk = di-2-pyridyl-ketone) have been synthesised and have been characterised both structurally and magnetically. The dpk·CH3OH ligand is the result of the metal-promoted solvolysis of dpk in methanol and acts as a neutral donor. X-ray analysis carried out on single crystals for both compounds revealed that compound 1 is dimeric exhibiting double (N,S)-thiocyanate bridges, while compound 2 is 1D consisting of chains in which the metallic centres are connected through single end-to-end NCS− groups. Magnetic susceptibility data showed that both compounds are antiferromagnetic, the values for the exchange constant J are −0.9 (1) and −0.3 cm−1 (2). The low values of J are consistent with the (Neq,Sax)-disposition of the thiocyanate bridges in the octahedral coordination sphere.