REGIOISOMERISM DISPLAYED BY THE 6-CHLORO-2-OXOPYRIDINATE COMPLEXES OF RU-2(4+) AND RU-2(5+)

Three new compounds containing either the RU(2)(4+) or the RU(2)(5+) core surrounded by four chp(-) ligands (where chp(-) represents the anion of 2-hydroxy-6-chloropyridine) have been prepared and structurally characterized. 2,2-Trans-[Ru-2(chp)(4)] (1) was obtained by reaction of Ru-2(O2CCH3)(4)Cl with molten Hchp (via the unisolated intermediate 0,4-[Ru-2(chp)(4)Cl]). It crystallizes in space group Pbca (No. 61) with a = 16.073(5), b = 18.603(5), c = 15.594(2) Angstrom, V = 4663(2) Angstrom(3), Z = 8. The Ru-Ru distance is 2.248(1) Angstrom. 0,4-[Ru-2(chp)(4)(THF)]. THF (2) was obtained by reduction of 0,4-[Ru-2(chp)(4)Cl] with zinc. It forms monoclinic crystals in space group P2(1)/c(No. 14) with a = 13.616(2), b = 12.820(3), c = 18.673(2) Angstrom, beta = 97.39(4)degrees, V = 3233(1) Angstrom(3), Z = 4. The Ru-Ru distance is 2.261(1) Angstrom. The compound {0,4[RU(2)(Chp)(4)]}(2)(BF4)(2) (3) was obtained from 0,4-[Ru-2(chp)(4)Cl] by removal of Cl- with Ag(CH3CN)(4)BF4. It crystallizes in space group P($)over tilde>1 (No. 2) with a = 12.995(3), b = 13.459(3), c = 10.640(3) Angstrom, alpha = 106.54(2), beta = 93.48(2), gamma = 65.78(2)degrees, V = 1623.5(7) Angstrom(3), Z = 1. The Ru-Ru distance is 2.254(1) Angstrom.