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)

Abstract

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 1 with NOBF₄ in CH₂Cl₂ yielded Cu(pyz)(cnge)(BF₄)₂2. Recrystallisation from MeCN resulted in loss of cnge and formation of [Cu(MeCN)₄(pyz)][BF₄]₂3. Reaction of 1 with NBu^t₄NO₂ in MeCN led to Cu(pyz)(cnge)(MeCN)(NO₂)₂4. 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 of 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).