Supramolecular chemistry and the control of the crystallization behavior by the choice of the counter-ion. Part 11. The stereochemistry and crystallization architecture of [(tren)Co(NO2)2]A (I), [(tren)Co(ox)]A (II), [(en)2Co(ox)]A (III) and [trans-(pn)2Co(NO2)2]A (IV), with A = [trans-(NH3)2Co(NO2)4] - 14/02/08
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Abstract |
In continuation of studies carried out previously [I. Bernal, Inorg. Chim. Acta 96 (1985) 99; I. Bernal, Inorg. Chim. Acta (1986) 121; I. Bernal, E.O. Schlemper, C.K. Fair, Inorg. Chim. Acta 115 (1986) 25; I. Bernal, Inorg. Chim. Acta 101 (1985) 175; I. Bernal, J. Cetrullo, J. Coord. Chem. 20 (1989) 237], we have now expanded the nature and number of cations associated with the [trans-(NH3)2Co(NO2)4] anion in order to better document when, and how, this helical propeller species crystallizes as a conglomerate.
[(tren)Co(NO2)2][trans-(NH3)2Co(NO2)4] (I) crystallizes as a racemate in space group P21/n with cell constants of a=15.8900(2), b=19.7800(3), c=26.6200(4)Å, β=101.970(3)°, z=15.
[(tren)Co(ox)][trans-(NH3)2Co(NO2)4] (II) crystallizes as a racemate in space group I2/a with cell constants of a=21.592(11), b=7.050(4), c=26.46(2)Å, β=93.09(6)°, z=8.
[(en)2Co(ox)][trans-(NH3)2Co(NO2)4] (III) crystallizes as a racemate in space group P21/n with cell constants of a=6.4740(1), b=22.8950(6), c=13.1660(3)Å, β=97.3310(10)°, z=4.
[trans-(pn)2Co(NO2)2][trans-(NH3)2Co(NO2)4] (IV) also crystallizes as a racemate in space group P(¯1; no. 2) with cell constants of a=6.508(2), b=8.829(5), c=9.851(5)Å, α=72.84(2), β=80.15(3), and γ=81.45(6)°, z=1.
The most notable results are as follows: (1) all four compounds studied are racemates unlike the previously studied [cis-Co(en)2(NO2)2][trans-(NH3)2Co(NO2)4] [I. Bernal, Inorg Chim Acta 101 (1985) 175] (V) and K[trans-(NH3)2Co(NO2)4] (VI) that crystallize as conglomerates. Nevertheless, they share certain crystalline features, which are readily observed in their packing diagrams.
In all the four cases the new data were collected at 295K and 120K, using Mo Kα radiation; the former with a Nonius CAD-4 diffractometer and the latter with a Nonius CCD instrument. Of primary interest to us are the changes in packing caused by repeated changes in the charge compensating cations. Comparisons with the packing observed previously in [cis-Co(en)2(NO2)2][trans-(NH3)2Co(NO2)4] (V) and K[trans-(NH3)2Co(NO2)4] (VI) are made since, at the time of publications of those early papers, no detailed study of the packing characteristics of these anions was published and the existing graphic software were primitive compared with the current packages. This oversight is remedied below.
Le texte complet de cet article est disponible en PDF.Keywords : Co(III) amine complexes, Co-NO2 complexes, Chirality in Co(III) complexes, Conglomerate crystallization of Co(III) complexes, X-ray diffraction studies of Co(III) complexes
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Vol 10 - N° 12
P. 1170-1179 - décembre 2007 Retour au numéro
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