Cu 2+ ‐Mediated Nucleophilic Addition of Different Nucleophiles to Dicyanamide – Synthesis, Structures, and Magnetic Properties of a Family of Mononuclear, Trinuclear, Hexanuclear, and Polymeric Copper(II) Complexes

Five new copper(II) complexes have been isolated from the reaction system of Cu II /N(CN) 2 – /HNu (HNu = pyrazole or MeOH) by Cu 2+ ‐mediated in situ nucleophilic additions of methanol or pyrazole to dicyanamide; they are [Cu(HdcadMeOH) 2 ](ClO 4 ) 2 · 2H 2 O ( 3 ), [Cu(dca) 2 (3‐nic) 2 ] n · (HdcaMeOH) 2 n ( 4 ), [Cu(dcapz)(dcadMeOH)] ( 5 ), [Cu 3 (dcadpz) 2 (Hpz) 2 (MeCN) 2 ](ClO 4 ) 2 (NO 3 ) 2 ( 6 ), and [Cu 6 (dcadpz‐2H) 2 (μ‐pz) 6 ] ( 7 ) [HdcadMeOH = bis(methoxycarbimido)amine, HdcaMeOH = (methoxycarbimido)cyanoamine, dcadMeOH – = bis(methoxycarbimido)aminato, dcapz – = (pyrazolecarbimido)cyanoaminato, dcadpz – = bis(pyrazolecarbimido)aminato, Hpz = pyrazole, 3‐nic = nicotinamide]. X‐ray crystallography revealed that 3 and 5 are mononuclear complexes, 6 is a trinuclear complex, 7 is a cyclic hexanuclear cluster, whereas 4 is composed of neutral one‐dimensional [Cu(μ 1,5 ‐dca) 2 (3‐nic) 2 ] n coordination chains with HdcaMeOH guest molecules located between these chains. In the five complexes, the 1:1 and 1:2 nucleophilic addition reactions occurred between dca – and methanol or pyrazole molecules under controlled conditions. In complexes 3 , 5 , 6 , and 7 , the addition products generated in situ act as bridging or chelating ligands, whereas in compound 4 the addition product acts as the guest molecule. The magnetic properties of complexes 6 and 7 were studied by variable‐temperature magnetic susceptibility and magnetization measurements. In 6 , significant ferromagnetic coupling exists between the three S = 1/2 spins within the Cu 3 unit through the dcadpz – bridges, whereas in 7 , strong antiferromagnetic couplings exist between the neighboring copper ions through the [dcadpz‐2H] 3– and pz – bridges with an intratrimer exchange interaction of –250.6 K and an intertrimer coupling interaction of –69.1 K. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)