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The reactions between [Cu(quin)2(H2O)] (quin− = the anionic form of quinoline-2-carboxylic acid) and a series of aliphatic amino alcohols have yielded structurally very diverse copper(II) complexes, labelled a–g. Single-crystal X-ray structure analysis has revealed either intact amino alcohol molecules or amino alcoholate ions serving as ligands. In type a complexes, the amino alcohols are bound in a monodentate manner via NH2. Engagement of both functional groups in coordination was observed for types b and e (a bidentate chelating mode) and type c (a bidentate bridging one) complexes. In view of the strong bidentate chelating coordination of quinaldinate in [Cu(quin)2(H2O)], the formation of homoleptic amino alcohol complexes e was not anticipated. Equally surprising was the transformation of a mononuclear starting material into a one-dimensional (1D) coordination polymer, [Cu(quin)2]n (g). Spontaneous deprotonation of some amino alcohols and coordination of, thus formed, amino alcoholates via both donors also took place. Dinuclear complexes (d) contained two bridging amino alcoholates, whilst bidentate chelating mode was observed for type f. Interestingly, the dinuclear complex exists as two isomers which differ in the position of quinaldinates with respect to the Cu(μ-OR)2Cu core. DFT calculations on isolated syn- and anti-[Cu2(quin)2(3a1pO)2] (3a1pO− = anion of 3-amino-1-propanol) have shown the syn isomer to be more stable. The explanation lies in the intramolecular π⋯π stacking of quinaldinates, possible only in this isomer. Magnetic susceptibility measurements revealed antiferromagnetic interactions between S = 1/2 copper(II) spins in all the studied compounds except in [Cu(quin)2]n (g) for which weak ferromagnetic couplings are detected. [ABSTRACT FROM AUTHOR]

To broaden the limited knowledge concerning the zinc(II) coordination chemistry with amino alcohols, reactions of [Zn(quin)2(H2O)] (quin− = quinaldinate, C10H6NO2) with 3-amino-1-propanol (3-apOH, C3H9NO) and N-methylaminoethanol (N-maeOH, C3H9NO) were investigated. The starting material, zinc(II) with two quinaldinates coordinated in a bidentate chelating mode, provides a structurally rigid core with two sites available for interaction with amino alcohol ligands. When the reactions were carried out in acetonitrile in autoclaves at 105 °C, an unforeseen decomposition of amino alcohols to ammonia took place. This was accompanied by crystallization of an ammine complex [Zn(quin)2(NH3)] (1). Mass spectrometry of the gaseous phases confirmed unambiguously the presence of ammonia in such reaction mixtures. The desired complexes with coordinated amino alcohols could be obtained in good yield by carrying out the reactions at room temperature and/or in various solvents. Two novel amino alcohol complexes were prepared, [Zn(quin)2(3-apOH)] and [Zn(quin)2(N-maeOH)]. The 3-apOH ligand was coordinated to zinc(II) in a monodentate manner via the amino nitrogen. The 3-apOH complex crystallizes as an acetonitrile (2a), ethanol (2b), 2-propanol (2c) or water (2d) solvate. The conversion of 2a to 2d was monitored by IR spectroscopy. In [Zn(quin)2(N-maeOH)] (3), the N-maeOH ligand was coordinated in a bidentate chelating manner through both functional groups. DFT calculations were performed on the isomers of [Zn(quin)2(3-apOH)] and [Zn(quin)2(N-maeOH)], which differ in the binding modes of their amino alcohol ligands. Complete characterization of all compounds by means of X-ray structure analysis, infrared spectroscopy and NMR spectroscopy is presented. [ABSTRACT FROM AUTHOR]