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⁻, , 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 complexRu(12]aneS3-S)₂](CF₃SO₃)₂ (3), in which only three sulfur atoms of each macrocycle are bound to ruthenium, are also described.