Interaction of silver(I) and copper(I) with an O2S2-macrocycle – A comparative structural study

Abstract

The 14-membered O2S2-macrocycle L reacts with AgPF6 in acetonitrile/dichloromethane (1:1) to yield the cyclic, double S–Ag–S bridged complex, [Ag2L2(CH3CN)4](PF6)2 (2), in which each Ag(I) is bound to two exo-oriented S donors arising from different macrocycles to form a 12-membered, di-Ag metallacycle. Two PF6− ions form weak intramolecular contacts [Ag⋯F, 2.925(2)Å] between the Ag centres in a bridging bidentate fashion. The coordination sphere of each Ag is completed by two weakly bound acetonitrile molecules. The respective macrocyclic ligands are arranged trans to the mean plane through the metallacycle. When the above synthetic procedure was repeated employing methanol/dichloromethane (1:1) as solvent, a complex of type [Ag2L2](PF6)2 (3) was obtained whose structure incorporates a similar 12-membered metallacycle but with the respective macrocyclic rings now oriented towards the same side of the metallacyclic plane. The reaction of L with AgCF3SO3 yields [Ag2L2(CF3SO3)2]·2CH3CN (4) whose structure resembles that of [Ag2L2(CH3CN)4](PF6)2 (2); each complex unit incorporates a di-Ag(I) 12-membered metallacycle, with symmetrical bridging bidentate CF3SO3− ions weakly linking Ag centres. Long Ag1⋯Ag1C contacts are present between pairs of complex units. Reaction of Cu(CH3CN)4PF6 (one equiv.) with L in methanol/dichloromethane (1:1) resulted in isolation of [CuL2]PF6 (5) incorporating a distorted tetrahedral S4-coordination sphere, with each macrocycle binding as a bidentate ligand via its two (exo-orientated) S atoms. In contrast, reaction of [Cu(CH3CN)4]PF6 (two equiv.) with L in either acetonitrile/dichloromethane (1:1) or methanol/dichloromethane (1:1) yielded [Cu2L3]PF6 (6) in which the Cu(I) centres are bound exo to the macrocyclic cavity by individual S-donors from one L, with the coordination sphere of each Cu(I) completed by out-of-plane binding of the S2O donors from a second L. Unsymmetrical F⋯Cu contacts from a PF6− anion weakly link the pair of Cu centres in a bridging bidentate fashion.