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The Phenomenon of Conglomerate Crystallization. Part 57. Control of the Crystallization Behavior by the Choice of the Counter Ion. Part 9. The Stereochemistry and Crystallization Architecture of [(3,2,3-tet)Co(N3)2]X (X = Cl(I), Br(II), I(III), NO3(IV), and PF6(V))

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posted on 30.03.2002, 00:00 by Manas K. Saha, Rathnakumar Ramanujam, Ivan Bernal, Frank R. Fronczek
Compounds of composition of [(3,2,3-tet)Co(N3)2]X (X = Cl(I), Br(II), I(III), NO3(IV), and PF6(V)) were prepared, and their crystal structures were determined at 295 and 120 K. Unlike a previous study by this group, in which we reported [Saha, M. K.; Bernal, I. Inorg. Chem. Commun. 2002, accepted for publication] a change of space group (P21/n to P21) upon cooling a cis-bis-diazido compound of Co(III), all the compounds described here retain their space groups upon cooling from 295 to 120 K. There are measurable changes in cell constants but no larger than what one normally expects. Details of the syntheses and of the crystallographic determinations are given below. A full description of the changes in stereochemistry of the [(3,2,3-tet)Co(N3)2]+ cations, as a result of changes in the counteranions, are detailed quantitatively, and superposition diagrams of the cations have been included to illustrate the changes in bond angles and torsional angles concomitant with the changes in anions and thus producing channel frameworks of different architecture. As expected, variations in bond lengths are minute, if at all, statistically valid. Compounds (I)−(IV) are racemates at all temperatures, while (V) is a conglomerate (space group P61 at 295 and 120 K), neatly illustrating the counteranion dependence of the phenomenon of conglomerate crystallization. Water molecules occupy channels in the framework of compound (I), which can be dehydrated and rehydrated without destruction of the crystal lattice.

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