The stereospecific synthesis of Lambda-alpha-{dipyrido[3,2-a:2'3'-c](6,7,8,9-tetrahydro)phenazine[N,N'-di(2-picolyl)-2,5-dimethyl-2S,5S-diaminocyclohexane]ruthenium(II)} and related beta isomers

The conglomerate Δ,Λ-α-[Ru(picchxnMe2)(dpqC)](ClO4)2·0.5H2O and Λ-α-[Ru(S,S-picchxnMe2)(dpqC)](ClO4)2·0.5H2O (where picchxnMe2 = N,N′-dimethyl-1,2-di(2′-picolyl)-S,S-diaminocyclohexane and dpqC = dipyrido[3,2-a:2′3′-c](6,7,8,9-tetrahydro)phenazine) have been isolated. Single crystal X-ray structures have been determined, although it was discovered only after initial data had been collected that the Δ,Λ-α-[Ru(picchxnMe2)(dpqC)](ClO4)2·0.5H2O species was in fact a conglomerate. Λ-α-[Ru(S,S-picchxnMe2)(dpqC)](ClO4)2·0.5H2O crystallises in the orthorhombic space group C2221 with a = 15.127(2), b = 22.976(4), c = 25.561(7) A, (alternatively a = 15.187(3), b = 23.003(6), c = 25. 685(7) A, for the separate determination of a crystal of the conglomerate), Z = 8, and the Λ-α structure was refined to an R value of 0.059. This structure enables, for the first time, the correlation of the absolute configurations for Ru(II) complexes of the N4 tetradentate with their CD spectra. We also report here a procedure to synthesise and isolate enantiomerically pure isomers of tetradentate metal complexes of the types α- and β-[Ru(R*,R*-picchxnMe2)(dpqC)]2+.