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### Topic: X-ray Crystallography- Why does this not satisfy 18 cubic angstrom rule?  (Read 1745 times)

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#### AlexDart10

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##### X-ray Crystallography- Why does this not satisfy 18 cubic angstrom rule?
« on: June 12, 2014, 09:26:11 PM »
Okay so our compound is [Et4N[Hg(SR)3]   aka (C26H53HgNS3) Formula weight 676.5
Volume= 1531.3A^3 and density = 1.467gcm^-3     Where R= Cyclohexyl group C6H11

Okay so first I calculated the Z value, converting both volume and density in to metres

Z= (DensityxvolumexNA)/RMM which gave me a value of essentially 2 (No solvent molecules present)

Then to calculate the average volume of non-H atoms I used Cell volume/(ZXnumber of H atoms)

1531.3/(31x2) gave me a value of 28, why does this not fit the rule? I'm guessing it has somethibg to do with the size of the ligands and Hg atoms but not entirely sure