engleski

Structural diversity in the coordination compounds of cobalt, nickel and copper with N- alkylglycinates: crystallographic and ESR study in the solid state

Reactions of N-methylglycine (HMeGly), N- ethylglycine-hydrochloride (H2EtGlyCl) and N- propylglycine-hydrochloride (H2PrGlyCl) with cobalt(II), nickel(II) and copper(II) ions in aqueous solutions resulted in ten new coordination compounds [Co(MeGly)2(H2O)2] (1), [{; ; ; ; ; Co(MeGly)2}; ; ; ; ; 2(μ-OH)2]·2H2O (1d), [Cu(MeGly)2(H2O)2] (2), [Co(EtGly)2(H2O)2] (3), [Ni(EtGly)2(H2O)2] (4), [Cu(μ-EtGly)2]n (5p), [Co(PrGly)2(H2O)2] (6), [Ni(PrGly)2(H2O)2] (7), and two polymorphs of [Cu(PrGly)2(H2O)2] (8α and 8β). Compounds were characterized by single-crystal and powder X- ray diffraction, infrared spectroscopy, thermal analysis and X-band electron spin resonance (ESR) spectroscopy. These studies revealed a wide range of structural types including monomeric, dimeric and polymeric architectures, as well as different polymorphs. In all monomeric compounds, except 2, and in the coordination polymer 5p hydrogen bonds interconnect the molecules into 2D layers with the alkyl chain pointing outward of the layer. In 2 and in the dimeric compound 1d hydrogen bonds link the molecules into 3D structures. 1d with cobalt(III), and 4 and 7 with nickel(II) are ESR silent. ESR spectra of 1, 3 and 6 are characteristic for paramagnetic high-spin cobalt(II). ESR spectra of all copper(II) coordination compounds show that the unpaired copper electron is located in the d_(x^2-y^2 ) orbital, being in agreement with the elongated octahedral geometry

cobalt ; nickel ; copper ; N-alkylglycinates

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