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(μ-L)]∞ (L = N(CN)2 -, 1; C(CN)3 -, 2) and [{Ru2(O2CCH3)2(mhp)2}2(μ-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 [Ru2(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) Å, b = 13.016(3) Å, c = 7.0750(14) Å, β = 101.83(3)°, and Z = 2. Compound 2 crystallizes in the orthorhombic space group Fdd2 with a = 29.679(6) Å, b = 31.409(6) Å, c = 7.3660(15) Å, V = 6866(2) Å3, and Z = 16. In compound 1, dicyanamide anions (N(CN)2 -) bridge the [Ru2(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 distances in 1 and 2 are 2.2788(14) and 2.2756(5) Å, respectively, which are typical values for Ru2(O2CR)4Cl and [Ru2(O2CR)4]+ compounds. The Ru−N distances are 2.257(8) Å in 1 and 2.259(4) and 2.283(4) Å in 2. The temperature dependence of the magnetic susceptibilities of compounds 1−3 reveals a weak antiferromagnetic interaction between Ru2 units (S = 3/2) through each polycyano anionic linker: g = 2.16, z J = −0.33 cm-1, D = 63.3 cm-1 for 1; g = 2.15, z J = −0.22 cm-1, D = 58.0 cm-1 for 2; and g = 2.10, z J = −0.90 cm-1, D = 75.0 cm-1 for 3.