The two-fold rotation symmetry of the individual complexes combined with the twist angle generates a four complex repeat unit for the chain. One consequence of this repeat unit is the apparent relction condition 00l, l=4n found in addition to an n-glide reflection condition. These two conditions do not coorespond to any space group, but careful examination of the first reveals weak violations that prodcue a true reflection condition00l, l=2n which, when combined with the n-glide, yields the tetragonal space group P42/n. This is an interesting structure to use as an illustration of the need of correctly identifying the space group. There is a fair amount of space group ambiguity at the start, but once the correct space group is chosen, the solution falls right out. It also illustrates the danger in rejecting violations of systematic absences. The violations observed here are weak enough to be dismissed as arising from double reflection (as is often done for weak violations), and their significance is easily missed.
Literature reference: Mohan, M., Bond, M. R., Otieno, T., and Carrano, C. J. "Oxovanadium Pyrazole Complexes: Synthesis and Structure" Inorg. Chem. 1995, 34, 1233-1242.
Companion Structure: None
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Last changed December 6, 1996