Metal-metal bonded diruthenium(II, III) assemblies with the polycyano anionic linkers N(CN)2-, C(CN)3-, and 1,4-dicyanamido-2,5-dimethylbenzene (DM-Dicyd2-):: Syntheses, structures, and magnetic properties

The new metal-metal bonded diruthenium(II,III) compounds [RU2(O2CCH3)(4)(mu -L)](infinity) = (L = N(CN)(2)(-), 1; C(CN)(3)(-), 2) and [{Ru-2(O2CCH3)(2)(mhp)(2)}(2)(mu -DM-Dicyd)] (3) (mhp = 2-oxy-6-methylpyridinate, DM-Dicyd = 1,4-dicyanamido-2,5-dimethylbenzene dianion) have been synthesized and fully characterized. Compounds 1 and 2 were synthesized by the reaction of [Ru-2(O2CCH3)(4)(NCCH3)(2)](BF4) with NaN(CN)(2) and KC(CN)(3), respectively. The "dimer-of-dimers", 3, was synthesized by a 2:1 reaction of [RU2(O2CCH3)(2)(mhp)(2)(MeOH)](BF4) with [As(Ph)(4)](2)[DM-Dicyd]. Compound 1 crystallizes in the monoclinic space group C2/m with a = 10.174(2) Angstrom, b = 13.016(3) Angstrom, c = 7.0750(14) Angstrom, beta = 101.83(3)degrees and Z = 2. Compound 2 crystallizes in the orthorhombic space group Fdd2 with a = 29.679(6) Angstrom, b = 31.409(6) Angstrom, c = 7.3660(15) Angstrom, V = 6866(2) Angstrom (3), and Z = 16. In compound 1, dicyanamide anions (N(CN)(2)(-)) bridge the [Ru-2(O2CCH3)(4)](+) units in an end-to-end bridging mode, thereby forming an alternating one-dimensional chain. In compound 2, two cyano groups of tricyanomethanide anion (C(CN)(3)(-)) are coordinated to independent [RU2(O2CCH3)(4)](+) units to give a chain similar to that found in 1. The Ru-Ru bond aistances in 1 and 2 are 2.2788(14) and 2.2756(5) Angstrom, respectively, which are typical values for Ru-2(O2CR)(4)Cl and [Ru-2(O2CR)(4)](+) compounds. The Ru-N distances are 2.257(8) Angstrom in 1 and 2.259(4) and 2.283(4) Angstrom in 2. The temperature dependence of the magnetic susceptibilities of compounds 1-3 reveals a weak antiferromagnetic interaction between Ru-2 units (S = 3/2) through each polycyano anionic linker: g = 2.16, zJ = -0.33 cm(-1), D = 63.3 cm(-1) for 1; g = 2.15, zJ = -0.22 cm(-1), D = 58.0 cm(-1) for 2; and g = 2.10, zJ = -0.90 (-1), D = 75.0 cm(-1) for 3.