Magnesium hexahydrate tetrachlorometallates are 50-volume-percent water, have a high melting point and possess a low vapor pressure. These new compounds are relatively noncorrosive, thermally stable, and water soluble but not hygroscopic. They may have potential applications as cooling fluids

Angell, C. A.

Gruen, D. M.

English

NASA Technical Reports Server

June 1967
	 Brief 67-10184 
Say C	
AEC-NASA TECH BRIEF 
US
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the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
New Class of Compounds Have Very Low Vapor Pressures 
The problem: 
To create a new class of compounds which are 50-
volume-percent water and have a melting point of 
about 170°C, yet possess a low vapor pressure at 
200°C. 
The solution: 
Magnesium Hex ahydrate Tetrachlorometallates: 
Mg(H 20) 6MC14, where M is a metal ion which can 
be either Zn, Fe, Cu, or Co. These compounds are 
relatively noncorrosive and thermally stable. They are 
water soluble but not hygroscopic. The Zn compound 
(Mg(H20) 6ZnCl4 ) has a vapor pressure of only one 
atmosphere at 200°C, while water has a vapor pressure 
of 15 atmospheres at this temperature. 
How it's done: 
These compounds are created in the laboratory by 
melting together in a sealed tube equimolar quantities 
of Mg(H20) 6C12 with anhydrous ZnC1 2, CoCl2 , FeC12, 
and CuCl 2 , respectively. The crystallization tempera-
tures of the 1: 1 mixtures are below 200°C in all cases. 
The Zn compound is colorless; the Co and Fe com-
pounds are deep blue and yellow, respectively; and 
the Cu compound is initially yellow, but changes to 
brown on standing. 
Although the crystal structures of these compounds 
have not yet been precisely determined, some infor-
mation about the 3d metal ions (M) can be deduced 
from the absorption spectra of . the compounds. 
ZnC142 and CoC142 tetrahedra appear to be present 
in the Zn and Co salts. Spectral data also indicate 
that in the Fe and Cu salts the coordination about 
the Fe and Cu is octahedral, with four vertices oc-
cupied by Cl and two by H20 molectrles which are 
shared with Mg(II). 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
The data collected to this point seem to indicate 
that a delicate balance of forces determines whether 
the (MCI4 ) groups in the crystalline state exist as 
isolated tetrahedral complex ion groups or whether 
they share an additional two H 20 molecules with the 
Mg(6H20) + + groups to give octahedral coordination 
of the 3d ions. 
Notes: 
1. These compounds may have potential applications 
as cooling fluids or in the production of high 
temperature steam at low pressures. 
2. These compounds were developed at Argonne Na-
tional Laboratories as the byproduct of other re-
search work. Thus little detailed experimentation 
has been done at this time and few concrete appli-
cations or properties data are available. This 
information is presented so that anyone interested 
in potential applications of the compounds may 
conduct the further research and development 
work necessary to adapt the compounds to specific 
needs. 
3. Additional information is contained in: Inorganic 
Nuclear Chemistry Letters, vol. 2, p. 75-78 
(1966). 
4. Inquiries concerning this innovation may be di-
rected to:
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B67-10184 
Source: D. M. Gruen and C. A. Angell 
Chemistry Division 
(ARG-115) 
(continued overleaf) 
liability resulting from the use of the information contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000184 2020-03-11T20:51:24+00:00Z
Patent status: 
Inquiries about obtaining rights for commercial use 
of this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439 
Brief 67-10184	 Category 03


New class of compounds have very low vapor pressures

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