Synthesis of tris(quinoxaline-2,3dithiolato)manganese(IV) and its reaction with [Cu(CH3COO)2H2O]2.: Crystal structure of [MnII(DMF)4(H2O)2][CuIII(qdt)2]2

Tris(quinoxaline-2,3-dithiolato)manganese(IV) was synthesised and isolated as two different salts, (PPh4)(2)[Mn-IV(qdt)(3)]. 1/2CHCl(3), 1, and (HNEt3)(2)[Mn-IV(qdt)(3)]. 2H(2)O, 2 (qdt = quinoxaline-2,3-dithiolate). The magnetic behaviour of 1 is the typical of a high spin d(3) system, presenting an effective magnetic moment of 3.85 mu(B), at room temperature. The reaction of 2 with copper(II) acetate in DMF (N,N-dimethylformamide) solution involves redox and ligand exchange processes and produces the new salt [Mn-II(DMF)(4) (H2O)(2)][Cu-III(qdt)(2)](2), 3. The crystal structure of compound 3 consists of sequences of two layers of [Cu-III(qdt)(2)](-) anions and one of [Mn-II(DMF)(4)(H2O)(2)](2+) cations. Each cation is linked to four anions through O H ... N hydrogen bonds between the water ligand of the cation and one nitrogen atom of qdt ligand in the anion. Magnetic isolation of the Mn(II) centres in 3 is confirmed by magnetic susceptibility measurements. (C) 1998 Elsevier Science Ltd. All rights reserved.