Oxidation of the pyrazine(pyz)-bridged polymeric copper(I) cation [Cu(cnge)(MeCN)(pyz)](+) by NOBF4 and formation of the corresponding copper(II) cation [Cu(MeCN)(4)(pyz)](2)+ (cnge=2-cyanoguanidine)

The complex [Cu(cnge)(MeCN)(pyz)]BF4 . 0.5pyz 1 (pyz = pyrazine, cnge = 2-cyanoguanidine) resulted from treatment of [Cu(MeCN)(4)]BF4 with mixtures of pyz and cnge in MeCN. Oxidation of compound I with NOBF4 in CH2Cl2 yielded Cu(pyz)(cnge)(BF4)(2) 2. Recrystallisation from MeCN resulted in loss of cnge and formation of [Cu(MeCN)(4)(pyz)][BF4](2) 3. Reaction of 1 with NBu(4)(t)NO(2) in MeCN led to Cu(pyz)(cnge)(MeCN)(NO2)(2) 4. Single-crystal X-ray structural analysis has shown compound 1 to contain a one-dimensional zigzag cationic chain based on four-co-ordinate tetrahedral copper(I); each metal atom is ligated by two bridging pyz molecules and terminal MeCN and cnge molecules, The unco-ordinated pyz molecule, which is located at an inversion centre; connects parallel copper(I) chains via N ... H-N bonds involving the amino moieties df ligating cnge molecules. The crystal structure of compound 3 contains a one-dimensional linear cationic chain based on six-co-ordinate copper(II), the tetragonally distorted octahedral co-ordination geometry of which comprises two bridging pyz molecules (equatorial) and four terminal MeCN molecules (two equatorial, two axial).