Copper perchlorate and tetrafluoridoborate compounds with the ligand 1,4,5-triazanaphthalene. Gradual transformation of mononuclear Cu(ii) compounds via polynuclear mixed-valence Cu(ii)/Cu(i) species to dinuclear Cu(i); Syntheses, characterizations and X-ray structures

Abstract

When the ligand 1,4,5-triazanaphthalene (abbreviated as tan) is reacted with Cu(ii) BF 4- and ClO 4- salts, a variety of mononuclear compounds has been found, all with the [Cu(tan) 4] unit and varying amounts of weakly coordinating axial ligands and lattice solvents. Reproducible compounds formed include two purple compounds, analyzing as [Cu(tan) 4](ClO 4) 2(CH 3OH) 2(H 2O) (1) and [Cu(tan) 4] (BF 4) 2(CH 3OH) 1.5(H 2O) (3), and two blue compounds, analyzing as [Cu(tan) 4](ClO 4) 2(H 2O) 2 (2) and [Cu(tan) 4] 2(BF 4) 2(H 2O) 2 (4). Upon standing at room temperature, red-coloured, mixed-valence dinuclear-based 3D coordination polymers are formed by conversion of the purple/blue products, of which [Cu 2(tan) 4] n(BF 4) 3n (5) and the isomorphic methanol-water adduct [Cu(tan) 4] n(BF 4) 3n(CH 3OH) n(H 2O) 5n (5A) are presented in this paper. In addition a fully reduced dinuclear Cu(i) compound of formula [Cu 2(tan) 3(ClO 4) 2] (7) has been observed, and structurally characterized, as a rare three-blade propeller structure, with a Cu-Cu distance of 2.504 Å. © 2012 The Royal Society of Chemistry.