Reaction of Copper Halides with Dafone and Halogens – Magnetic Exchange in Dibromine Linked Chains of Cu(dafone) < inf > 2 < /inf > X < inf > 2 < /inf >

Abstract

The reaction of CuII halides with 4,5-diazaflouren-9-one (dafone) in acetonitrile and in the presence of halogens gave four novel compounds: [Cu(dafone)2Cl2]Br2 (1), [Cu(dafone)2Br2]Br2 (2), [Cu(dafone)2(CH3CN)2](IBr2)2 (3), and [Cu(dafone)2(CH3CN)2](Br3)2(Br2)2 (4). The well-known preference of dafone to form an unsymmetrical chelate with Cu2+ directs the halide ion and acetonitrile to the equatorial plane of the octahedral complex. In 1 and 2, dibromine links the neutral halo complex molecules to form infinite chains of the previously known neutral molecules. The acetonitrile complex in 3 has the symmetrical mixed trihalide (IBr2–) as a counterion, while in 4 the cation is surrounded by a tribromide-dibromine network. Raman, EPR, optical absorption, and luminescence characteristics are discussed. The dibromine molecules in 1 and 2 provide a pathway for weak magnetic coupling along the chain polymer.