Dear Reader,
While reading about fusion reactors, I noticed that an alternative molten salt can be used, this is a 1:1:1 mixture of LiF, NaF and BeF2. I expect that this will be rather similar to Li2BeF4 but I could not resist having a look in the crystallography database. I found that a report exists of Na3Li.2[BeF4] (J. Vicat, Duc Tran Qui, S. Aleonard and P. Richard, Acta Crystallographica B, 1974, 30(11), 2678-2682).
This is a more complex solid that the Li2BeF4, the lithium is five coordinate (distorted trigonal based pyramidal).
A view of the coordination environment of the lithium. The lithium in orchid, the sodium is in yellow, the flourine in green and the beryllium in blue.
Two of the sodiums has a distorted square based pyramidal geometry. (Na1 and Na2). While Na3 is six coordinate the geometry is so distorted away from octahedral that I can not tell what it is. Here is a picture of Na1′s coordination environment.
The coordination environment of Na1
One of the berylliums (Be1) is has a nice and regular looking tetrahedral environment. I think that the important thing is that with the Be:F ratio of 1:4 we have the nice tetrahedrons.
The coordination environment of Be1
The other (Be2) has a distorted tetrahedral environment (one bond is longer than the others, this is the bond to the flourine bonding to the sodium and the lithium).
Coordination environment of Be2
Also a report exists of a Na2LiBeF7 by G. Brunton, Materials Research Bulletin, 1972, 7, 641-646. I will get onto that one in the next post on Be chemistry.
Filed under: beryllium, Uncategorized
