New ruthenium(II) precursors with the tetradentate sulfur macrocycles tetrathiacyclododecane ([12]aneS4) and tetrathiacyclohexadecane ([16]aneS4) for the construction of metal-mediated supramolecular assemblies

The preparation and structural characterization of several new Ru(II) complexes in which four coordination positions are occupied by the sulfur atoms of a macrocycle, either 1,4,7,10-tetrathiacyclododecane ([12]aneS4) or 1,5,9,13-tetrathiacyclohexadecane ([16]aneS4), and the two others by relatively labile ligands (Cl−, View the MathML sourceNO3-, H2O, dmso-S), are described:cis-[Ru([12]aneS4)(dmso-S)(H2O)](CF3SO3)2 (2a), cis-[Ru([12]aneS4)(dmso-S)(ONO2)](NO3) (2b), cis-[Ru([16]aneS4)Cl2] (4), and trans-[Ru([16]aneS4)(dmso-S)(H2O)](CF3SO3)2 (5).The complexes of the larger [16]aneS4 macrocycle have a flexible coordination geometry, either cis or trans, that makes them unsuited for being used as precursors in metal-driven self-assembly processes.On the contrary, the [12]aneS4 complexes cis-[Ru([12]aneS4)(dmso-S)Cl]Cl (1) and, above all, its chlorido free derivatives cis-[Ru([12]aneS4)(dmso-S)(H2O)](CF3SO3)2 (2a) and cis-[Ru([12]aneS4)(dmso-S)(ONO2)](NO3) (2b) are potential precursors of the geometrically stable 90° bis-acceptor fragment cis-[Ru([12]aneS4)]2+.Preliminary results of their reactivity towards the linear linker pyrazine (pyz) showed that the nature of the isolated product depends on that of the counter-anion.When treated with pyz 2b afforded the dinuclear complex [{Ru([12]aneS4)(ONO2)}2(μ-pyz)](NO3)2 (8), while 2a gave the molecular triangle [{cis-Ru([12]aneS4)(μ-pyz)}3](CF3SO3)6 (9), both in low yields.The X-ray structures of compounds 2a, 2b, 4, 5, [{Ru([12]aneS4)Cl}2(μ-pyz)]Cl2 (7), 9, and of the sandwich complex[Ru([12]aneS3-S)2](CF3SO3)2 (3), in which only three sulfur atoms of each macrocycle are bound to ruthenium, are also described.