engleski

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

wo 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- 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 - 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.

catalysis; chromium(III); crystal structures; pyrazole

nije evidentirano