Synthesis and characterization of the series of compounds Ru2(O2CMe)x(admp)4-xCl (Hadmp = 2-amino-4,6-dimethylpyridine, x = 3, 2, 1, 0)

The reaction between Ru-2(O2CMe)(4)Cl and Hadmp (Hadmp = 2-amino-4,6-dimethylpyridine) under different conditions has been investigated. By conducting the reaction in a methanol solution at room temperature the product obtained was Ru-2(admp)(O2CMe)(3)Cl (1). In a melt reaction at 65 degrees C the product isolated is Ru-2(admp)2(O2CMe)(2)Cl (2); at 100 degrees C it is Ru-2(admp)(3)(O2CMe)Cl (3); and at 140 degrees C it is Ru-2(admp)(4)Cl (4). The generality of these reactions was confirmed by the deliberate preparation of Ru-2(chp)(3)(O2CMe)Cl (5) and [Ru-2(DPhTA)(3)(O2CMe)(NCMe)(2)][BF4] (6). The structures of 1, 2, and 3 were determined by X-ray crystallography. The structure of 1 was determined from crystals of 1 . 3CH(2)Cl(2) (C16H24Cl7N2O6Ru2), triclinic, P (1) over bar (No. 2), with a = 11.578(3) Angstrom, b = 12.5607(13) Angstrom, c = 20.903(3) Angstrom, alpha = 99.927(14)degrees, beta = 100.222(9)degrees, gamma = 102.07(2)degrees, Z = 4; that of 2, from crystals of 2 . 2.5CH(2)Cl(2) (C21H30Cl7N4O4Ru2), monoclinic, P2(1)/n (No. 14), with a = 13.091(3) Angstrom, b = 19.098(4) Angstrom, c = 13.720(3) Angstrom, beta = 105.51(3)degrees; that of 3, from crystals of 3 . Hadmp . C6H6 (C36H46ClN8O2Ru2), monoclinic, P2(1)/n (No. 14), with a = 15.979(2) Angstrom, b = 14.9294(14) Angstrom, c = 17.131(4) Angstrom, beta = 109.21(2)degrees. The magnetic susceptibilities and electrochemistry of the four title compounds were also studied. It was observed that while compounds 1, 2, and 3 display magnetic moments compatible with the presence of three unpaired electrons and all yield stable one-electron oxidation products, 4 shows only one unpaired electron and the product of its one-electron oxidation decays sufficiently rapidly that no return wave is observed.