Chromium coordination compounds with bis(3,5-dimethylpyrazol-1-yl)acetic acid or its anion

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• 作者：Nives Kitanovski ; Nata拧a Borsan ; Marta Kasuni膷 ; Vojmir Franceti膷 ; Jasminka Popovi膰 ; Igor Djerdj ; Xavier Rocquefelte ; Jan Reedijk ; Bojan Kozlev膷ar
• 关键词：Chromium(III) ; Pyrazole ; Crystal structures ; Spectroscopy ; Catalysis
• 刊名：Polyhedron
• 出版年：9 March, 2014
• 年：2014
• 卷：70
• 期：Complete
• 页码：119-124
• 全文大小：975 K

文摘

Two chromium(III) coordination compounds synthesized from a solution of the tridentate (NON) ligand bis(3,5-dimethylpyrazol-1-yl)acetic acid (HL = Hbdmpza), namely [Cr(L)₂](H(NO₃)₂) (1) and [Cr(HL)Cl₃] (2), are reported. The centrosymmetric central coordination sphere in compound 1 is fulfilled by two deprotonated ligands L^{鈭?/sup> giving sterically closed coordination shell with pink-orange colored CrO₂N₄ chromophore. The coordination cation is accompanied by the dinitratohydrogenate(1-) counter anion. Contrary to compound 1, the compound 2 shows only one Hbdmpza ligand, which is protonated HL, though with the same three coordinate N,O,N atoms. Both title compounds 1 and 2 were isolated from the acetonitrile solution with the starting counter-anion remaining in the final product as a new counter anion H(NO₃)₂鈭?/sup> in 1, or the coordinated chloride anions in 2 with green colored CrON₂Cl₃ chromophore. We were able to isolate the single crystals of 1, while only polycrystalline material for 2. Nevertheless, the crystal structure of 2 containing two octahedral coordination molecules in the asymmetric unit was determined via the combination of DFT calculations and the powder XRD analysis. Though both compounds reveal a mononuclear octahedral coordination motif, the catalytic accessibility of the compound 2, due to only one tridentate ligand L (HL) per one Cr(III) centre clearly promises more to this aspect.}