Ni1.282(4)Si1.284(5)P3 or NiSi2P3: Two Solutions with Different Atom Distributions for One Single-Crystal X-Ray Data Set, Both Refined to Residuals of Less Than 2.5%
✍ Scribed by Jörg Wallinda; Wolfgang Jeitschko
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 250 KB
- Volume
- 114
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
The crystal structure of (\mathrm{NiSi}{2} \mathrm{P}{3}(\mathrm{lmm} 2, a=350.5(1) \mathrm{pm}, b=) 1107.1(3) pm, (\mathrm{c}=530.7(1) \mathrm{pm}, Z=2) ), previously reported with the composition (\mathrm{Ni}{1.68} \mathrm{i}{0.88} \mathrm{P}{3}), was redetermined from single-crystal X-ray data. The original structure proposed with mixed (\mathrm{Ni} / \mathrm{Si}) occupancy of one atomic site and partial Si occupancy of another site was refined to a residual (R=0.023). For the correct model with a different atom distribution and full occupancy of all atomic sites, the residual is 0.020 for 739 structure factors and 21 variable parameters. The structure of (\mathrm{NiSi}{2} \mathrm{P}{3}) corresponds to a superstructure of the cubic sphalerite with the nickel and silicon atoms occupying the zinc positions of (\mathrm{ZnS}) in an ordered manner, while the positions of the phosphorus atoms correspond to the sulfur positions. Comsequenty the nickel atoms obtain the oxidation number +1 , while the unusually high oxidation number +3.88 is obtained for the composition (\mathrm{Ni}{1.2824)} S \mathrm{~S}{1.284(5)} \mathrm{P}{3}) refined for the incorrect model. 1995 Academic Press. Inc.