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Two new Ar-BIAN Cu(II) complexes (where Ar-BIAN = bis(aryl-imino)acenaphthene) of formulations [CuCl2(Mes-BIAN)] (1) (Mes = 2,4,6-Me3C6H2) and [CuCl2(Dipp-BIAN)] (2) (Dipp = 2,6-iPr2C6H3) were synthesised by direct reaction of CuCl2 suspended in dichloromethane with the respective ligands Mes-BIAN (L1) and Dipp-BIAN (L2), dissolved in dichloromethane, under an argon atmosphere. Attempts to obtain these compounds by solubilising CuCl2 in methanol and adding a dichloromethane solution of the corresponding ligand, under aerobic conditions, gave also compound 1, but, in the case of L2, the Cu(I) dimer [CuCl(Dipp-BIAN)]2 (3) was obtained instead of compound 2. The compounds were fully characterised by elemental analyses, MALDI-TOF mass spectrometry, FT-IR, (1)H NMR and EPR spectroscopic techniques. The solid-state molecular structures of compounds 1-3 were determined by single crystal X-ray diffraction, showing the expected chelation of the Ar-BIAN ligands and two chloride ligands completing the coordination sphere of the Cu(II) centre. In the case of the complex 1, an intermediate coordination geometry around the Cu(II) centre, between square planar and tetrahedral, was revealed, while the complex 2 showed an almost square planar geometry. The structural differences and evaluation of energetic changes were rationalised by DFT calculations. Analysis of the electrochemical behaviour of complexes 1-3 was performed by cyclic voltammetry and the experimental redox potentials for Cu(II)/Cu(I) pairs have been compared with theoretical values calculated by DFT in the gas phase and in dichloromethane and methanol solutions. The complex 1 exhibited good activity in the reverse atom transfer radical polymerisation (ATRP) of styrene.

A new neutral dimeric Ar‐BIAN Cu(I) complex (where Ar‐BIAN = bis(aryl‐imino)acenaphthene) of formulation [CuBr(4‐iPrC6H4‐BIAN)]2 (2) was obtained by reacting CuBr and ligand 4‐iPrC6H4‐BIAN (L2) in refluxing acetonitrile under an argon atmosphere. When the ligand used was 2,4,6‐Me3C6H2‐BIAN (L1), we obtained 1 in which the expected dimer (1a) is present, but we could also observe, in solution, the presence of the bis‐chelate dimer [Cu(2,4,6‐Me3C6H2‐BIAN)2][CuBr2] (1b) bearing CuBr2− as counter‐ion; attempts to separate them failed. When the ligand used was 2‐iPrC6H4‐BIAN (L3), we obtained 3 in which the expected dimer (3a) is in equilibrium, in solution, with its bis‐chelate isomer [Cu(2‐iPrC6H4‐BIAN)2][CuBr2] (3b). The solid‐state molecular structures of compounds 2 and 3b were determined by single crystal X‐ray diffraction. The electrochemical behaviour of complexes: 1 (1a, and 1b), 2, and 3 (3a and 3b) and the known compound [Cu(2‐iPrC6H4‐BIAN)2][BF4] (7) were investigated by cyclic voltammetry. The new complexes 1 (1a, 1b), 2, and 3 (3a, 3b) were tested as catalysts for the aerobic oxidation of benzylic alcohols into aldehydes; they all catalyse the reaction, with good results; the catalytic studies were extended to the similar known complexes [CuBr(2,6‐iPr2C6H3‐BIAN)]2 (4), [CuI(2,6‐iPr2C6H3‐BIAN)]2 (5), [CuCl(2,6‐iPr2C6H3‐BIAN)]2 (6) and (7), in order to study the effect of different bridging halides or counter ions in the catalytic activity. We found that compound 4 exhibited a high catalytic activity comparable to the best results published so far. The oxidation products, benzaldehydes, were detected and further confirmed by NMR spectroscopy, and the conversion rate was determined after GC‐FID analysis. [ABSTRACT FROM AUTHOR]

A series of nine cationic heteroleptic aryl-BIAN-copper(I) (BIAN = bis-iminoacenaphthene) complexes with the general formula [Cu((E-C6H4)2BIAN)(PPh3)2][X] (E = p-Me, p-iPr, o-iPr; X = BF4, OTf, NO3) 1X–3X were synthesized and fully characterized using several analytical techniques, including NMR spectroscopy and single-crystal X-ray diffraction. Except for complexes 2BF4 and 3BF4, which were already reported in our previous works, all remaining complexes are herein described for the first time. Two different strategies were used for the preparation of the complexes: complexes bearing BF4− or OTf− counter-ions (1BF4, 1OTf, 2OTf, and 3OTf) were obtained using the appropriate copper(I) precursors [Cu(NCMe)4][BF4] or [Cu(NCMe)4][OTf], whereas for derivatives 1NO3–3NO3, [Cu(PPh3)2NO3] was used. Their activity as catalysts for the copper azide-alkyne cycloaddition (CuAAC) was assessed alongside other high activity, previously reported Cu(I) complexes. Comparative studies to determine the influence of the counter-ion and of the aryl substituents were performed. All complexes behaved as active catalysts under neat reaction conditions, at 25 °C and in short reaction times without requiring the use of any additive, with complex 2NO3 being the most efficient derivative, along with other NO3−-bearing complexes. [ABSTRACT FROM AUTHOR]

A series of new cationic and neutral (Ar-BIAN)copper(I) complexes [in which Ar-BIAN = bis(aryl)acenaphthenequinonediimine] was synthesised and characterised by elemental analysis, 1D and 2D NMR spectroscopy and single-crystal X-ray diffraction. The cationic complexes of the general formula [Cu(Ar-BIAN) L2]BF4 [ L2 = (PPh3)2 ( 1), dppe ( 2), dppf ( 3), (AsPh3)2 ( 4); Ar = 4- iPrC6H4 ( a), 4-MeOC6H4 ( b), 4-NO2C6H4 ( c), 2- iPrC6H4 ( d), Ph2PCH2CH2PPh2 (dppe), (Ph2PC5H4)2Fe (dppf)] were synthesised by reaction of [Cu(EPh3)4]BF4 (E = P or As) and equimolar amounts of Ar-BIAN ligands, or by reaction of equimolar amounts of [Cu(NCMe)4]BF4, 4- iPrC6H4-BIAN ( a) and diphosphanes dppe or dppf, in dichloromethane, whereas the neutral complexes of the types [CuX(Ar-BIAN)(EPh3)] [X = Cl, E = P ( 5); X = I, E = P ( 6); X = Cl, E = As ( 9)] and [{CuX(Ar-BIAN)}2] [X = Cl ( 7), I ( 8); Ar = a, b, c, d, 2,4,6-Me3C6H2 ( e), 2,6- iPr2C6H3 ( f)] were prepared by reaction of CuCl or CuI with equimolar amounts of Ar-BIAN and EPh3 (E = P, As or Sb) in acetonitrile under reflux conditions. The type of ancillary ligand EPh3 and the aryl substituents on Ar-BIAN play crucial roles in determining the formation of cationic or neutral copper(I) complexes. No copper(I) complexes containing coordinated SbPh3 were isolated; all the corresponding attempts led to dimeric complexes 7 or 8. Most of the complexes crystallised easily. Their study by X-ray diffraction revealed distorted-tetrahedral geometries around the copper(I) centres, which are quite influenced by the various aryl substituents on Ar-BIAN and the ancillary ligands EPh3. All complexes 1- 9 except cationic dppf derivative 3a are active catalysts for cycloaddition reactions of alkynes and azides, and also show good tolerance towards functionalised substituents of alkynes and azides. Among them, the PPh3-coordinated complexes 1, 5 and 6 afforded the highest catalytic activities [turnover frequency = 26.9-45.7 h-1]. [ABSTRACT FROM AUTHOR]