title: Synthesis and structural characterisation of (aryl-BIAN)copper(I) complexes and their application as catalysts for the cycloaddition of azides and alkynes.
abstract: A series of Ar-BIAN-based copper(I) complexes (where Ar-BIAN = bis(aryl)acenaphthenequinonediimine) were synthesised and characterised by (1)H and (13)C NMR spectroscopies, FT-IR spectroscopy, MALDI-TOF-MS spectrometry, cyclic voltammetry and single crystal X-ray diffraction. The bis-chelated complexes of general formula [Cu(Ar-BIAN)(2)]BF(4) (where Ar = C(6)H(5) (1), 4-iPrC(6)H(4) (3), 2-iPrC(6)H(4) (4)) were prepared by reaction of [Cu(NCMe)(4)]BF(4) with two equivalents of the corresponding Ar-BIAN ligands, in dichloromethane, while the mono-chelated complexes of the type [Cu(Ar-BIAN)L(2)]BF(4) (where Ar = 2,6-iPr(2)C(6)H(3), L = PhCN (6); Ar = 4-iPrC(6)H(4), L = PPh(3) (7)) were readily accessible by treatment of [Cu(NCR)(4)]BF(4) (R = Me, Ph) with one equivalent of the corresponding Ar-BIAN ligands in the absence or presence of two equivalents of PPh(3), in the same solvent. The structures of complexes 3, 4, 6 and 7 were obtained by single crystal X-ray diffraction, showing distorted tetrahedral geometries around the copper centres in all cases. The electrochemical studies of these complexes and of the already reported [Cu(2,4,6-Me(3)C(6)H(2)-BIAN)(2)]BF(4) (2) and [Cu(2,6-iPr(2)C(6)H(3)-BIAN)(NCMe)(2)] (5), demonstrated that the bis-chelated complexes 1-4 undergo a reversible one-electron reduction or oxidation processes on copper, while the mono-chelated complexes 5-7 show a partially reversible oxidation and an irreversible reduction feature. Both kinds of (Ar-BIAN)copper(I) complexes are active catalysts for the copper(I)-catalysed azide-alkyne cycloaddition reaction (CuAAC). Complex 7, bearing PPh(3) ligands, exhibits the highest catalytic activity, which is comparable with that of the typical CuSO(4)-sodium ascorbate catalyst system.
authors.affiliation: Centro de Química Estrutural, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: Lidong
authors.initials: L
authors.lastname: Li
authors.forename: Patrícia S
authors.initials: PS
authors.lastname: Lopes
authors.forename: Vitor
authors.initials: V
authors.lastname: Rosa
authors.forename: Cláudia A
authors.initials: CA
authors.lastname: Figueira
authors.forename: M Amélia N D A
authors.initials: MA
authors.lastname: Lemos
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Duarte
authors.forename: Teresa
authors.initials: T
authors.lastname: Avilés
authors.forename: Pedro T
authors.initials: PT
authors.lastname: Gomes
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D001386:Azides / Q000737:chemistry*; D002384:Catalysis; D060326:Chemistry Techniques, Synthetic / Q000379:methods*; D003300:Copper / Q000737:chemistry*; D004563:Electrochemistry; D007097:Imines / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D000480:Alkynes; D001386:Azides; D007097:Imines; D009942:Organometallic Compounds; D003300:Copper