TY - JOUR
T1 - A Revised Structure Model for the UCl
6
Structure Type, Novel Modifications of UCl
6
and UBr
5
, and a Comment on the Modifications of Protactinium Pentabromides
AU - Deubner, H. Lars
AU - Rudel, Stefan S.
AU - Sachs, Malte
AU - Pietzonka, Clemens
AU - Karttunen, Antti J.
AU - Ivlev, Sergei I.
AU - Müller, Matthias
AU - Conrad, Matthias
AU - Müller, Ulrich
AU - Kraus, Florian
N1 - FAM on suljettu, kunnes embargoaika voidaa määritellä.MSo/26.4.19
PY - 2019/5/2
Y1 - 2019/5/2
N2 - The redetermination of the crystal structure of trigonal UCl 6 , which is the eponym for the UCl 6 structure type, showed that certain atomic coordinates had been incorrectly reported. This led to noticeably different U−Cl distances within the octahedral UCl 6 molecule (2.41 and 2.51 Å). Within the revised structure model presented here, which is based on single crystal data as well as quantum chemical calculations, all U−Cl distances are essentially equal within standard uncertainty (2.431(5), 2.437(5), and 2.439(6) Å). This room temperature modification, called rt-UCl 6 , crystallizes in the trigonal space group P (Formula presented.) m1, No. 164, hP21, with a=10.907(2), c=5.9883(12) Å, V=616.9(2) Å 3 , Z=3 at T=253 K. A new low-temperature (lt) modification of UCl 6 is also presented that was obtained by cooling a single crystal of rt-UCl 6. The phase change occurs between 150 and 175 K. lt-UCl 6 crystallizes isotypic to a low-temperature modification of SF 6 in the monoclinic crystal system, space group C2/m, No. 12, mS42, with a=17.847(4), b=10.8347(18), c=6.2670(17) Å, β=96.68(2)°, V=1203.6(5) Å 3 , Z=6 at 100 K. The Cl anions form a close-packed structure corresponding to the α-Sm type with uranium atoms in the octahedral voids. During the synthesis of UBr 5 a new modification was obtained that crystallizes in the triclinic crystal system, space group P (Formula presented.), No. 2, aP36, with a=10.4021(6), b=11.1620(6), c=12.2942(7) Å, α=68.3340(10)°, β=69.6410(10)° and γ=89.5290(10)°, V=1231.84(12) Å 3 , Z=3 at T=100 K. In this structure the UBr 5 units are dimerized to U 2 Br 10 molecules. The Br anions also form a close-packed structure of the α-Sm type with adjacent uranium atoms in the octahedral voids. Comparisons of the crystal structures of the compounds MX 5 (M=Pa, U; X=Cl, Br) show that the crystal structure of monoclinic α-PaBr 5 is probably not correct.
AB - The redetermination of the crystal structure of trigonal UCl 6 , which is the eponym for the UCl 6 structure type, showed that certain atomic coordinates had been incorrectly reported. This led to noticeably different U−Cl distances within the octahedral UCl 6 molecule (2.41 and 2.51 Å). Within the revised structure model presented here, which is based on single crystal data as well as quantum chemical calculations, all U−Cl distances are essentially equal within standard uncertainty (2.431(5), 2.437(5), and 2.439(6) Å). This room temperature modification, called rt-UCl 6 , crystallizes in the trigonal space group P (Formula presented.) m1, No. 164, hP21, with a=10.907(2), c=5.9883(12) Å, V=616.9(2) Å 3 , Z=3 at T=253 K. A new low-temperature (lt) modification of UCl 6 is also presented that was obtained by cooling a single crystal of rt-UCl 6. The phase change occurs between 150 and 175 K. lt-UCl 6 crystallizes isotypic to a low-temperature modification of SF 6 in the monoclinic crystal system, space group C2/m, No. 12, mS42, with a=17.847(4), b=10.8347(18), c=6.2670(17) Å, β=96.68(2)°, V=1203.6(5) Å 3 , Z=6 at 100 K. The Cl anions form a close-packed structure corresponding to the α-Sm type with uranium atoms in the octahedral voids. During the synthesis of UBr 5 a new modification was obtained that crystallizes in the triclinic crystal system, space group P (Formula presented.), No. 2, aP36, with a=10.4021(6), b=11.1620(6), c=12.2942(7) Å, α=68.3340(10)°, β=69.6410(10)° and γ=89.5290(10)°, V=1231.84(12) Å 3 , Z=3 at T=100 K. In this structure the UBr 5 units are dimerized to U 2 Br 10 molecules. The Br anions also form a close-packed structure of the α-Sm type with adjacent uranium atoms in the octahedral voids. Comparisons of the crystal structures of the compounds MX 5 (M=Pa, U; X=Cl, Br) show that the crystal structure of monoclinic α-PaBr 5 is probably not correct.
KW - bromide
KW - chloride
KW - crystal structures
KW - protactinium
KW - uranium
UR - http://www.scopus.com/inward/record.url?scp=85064092543&partnerID=8YFLogxK
U2 - 10.1002/chem.201900389
DO - 10.1002/chem.201900389
M3 - Article
AN - SCOPUS:85064092543
SN - 0947-6539
VL - 25
SP - 6402
EP - 6411
JO - Chemistry: A European Journal
JF - Chemistry: A European Journal
IS - 25
ER -