title: Amine mediated proton transfer reaction and C-Cl bond activation of solvent chloroform by a trinuclear copper(II) complex of a glucopyranosylamine derived ligand.
abstract: An amine mediated C-Cl bond activation process of the solvent chloroform has been explored by a coordinatively labile trinuclear Cu(II) complex, [Cu3(L1)2(MeOH)(H2O)] (1), derived from N-(3-tert-butyl-2-hydroxybenzylidene)-4,6-O-ethylidene--D-glucopyranosylamine (H3L1). The effect of activation is extremely high with methylamine, resulting in the formation of [Cu(MeNH2)5]Cl2 (2) and [Cu(L2)2] (3; HL2 = 2-tert-butyl-6-[(methylimino)methyl]phenol), however, under identical conditions it is moderate with ethylamine resulting in the isolation of crystals of the intermediate amine bound trinuclear copper(II) complex, [Cu3(L1)2(EtNH2)2(MeOH)2] (5), which was further converted into the mononuclear complex, [Cu(HL1)(EtNH2)] (6), in a novel crystal-to-crystal transformation. The successive isolation of the ethylamine-bound tri- and mononuclear complexes, 5 and 6, supported the occurrence of proton transfer reactions, which might be a key step in C-Cl bond activation. The primary and secondary amines, 2-aminomethylpyridine, N,N-dimethylethylenediamine, and 1,4,7-triazacyclononane, also having chelating features further enhance the rate of activation. No activation has been noted in the case of triethylamine and N,N,N,N-tetramethylethylenediamine. Formation of a carbene-trapped compound, 2,6-xylyl isocyanide, was confirmed in the reaction of complex 1 with 1,4,7-triazacyclononane and 2,6-xylidine in CHCl3, suggesting that the C-Cl bond cleavage led to the generation of dichlorocarbene. In addition, the mononuclear complex 6 has been transformed into a homotrinuclear complex [Cu3(L1)2(MeOH)2] by treatment with Cu(II) ions in MeOH/CHCl3, suggesting the possibility that the former could be regarded as a suitable metalloligand for heterotrimetallic complex synthesis.
authors.affiliation: Department of Chemistry, Faculty of Science, Nara Women's University, Kitauoya-higashi-machi, Nara, 630-8285, Japan.
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Sah
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Tanase
mesh_terms: D000588:Amines / Q000737:chemistry*; D002725:Chloroform / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005021:Ethylamines / Q000737:chemistry; D005944:Glucosamine / Q000031:analogs & derivatives* / Q000737:chemistry; D006574:Heterocyclic Compounds, 2-Ring / Q000737:chemistry; D006860:Hydrogen Bonding; D008024:Ligands; D008744:Methylamines / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D011522:Protons; D012545:Schiff Bases / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000588:Amines; D005021:Ethylamines; D006574:Heterocyclic Compounds, 2-Ring; D008024:Ligands; D008744:Methylamines; D011522:Protons; D012545:Schiff Bases; D012997:Solvents; C075822:glucopyranosylamine; D003300:Copper; D002725:Chloroform; C027451:methylamine; D005944:Glucosamine; C041564:ethylamine