The Pseudo-Symmetric Structure of Pb(SPh)2

• Published in: Acta crystallographica. Section B, Structural science Vol. 53; no. 3; pp. 457 - 465
• Main Authors: Rae, A. D., Craig, D. C., Dance, I. G., Scudder, M. L., Dean, P. A. W., Kmetic, M. A., Payne, N. C., Vittal, J. J.
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01-06-1997; Blackwell
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Inorganic compounds; Miscellaneous; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Organic anion; Inorganic compounds; Molecular structure; Thiolate; Organic salt; Benzenic compound; Lead compounds; XRD; Experimental study; Crystal structure
• DOI: 10.1107/S0108768196015819
• EISSN: 1600-5740
• ISSN: 0108-7681

The crystal structure of Pb(SC
6
H
5
)2 is pseudo-
C
-centred orthorhombic,
a
= 54.06 (1),
b
= 11.468 (1),
c
= 7.4387 (8) Å, \alpha = \beta = \gamma = 90°,
Z
= 16, and may be described as a partial ordering of a 1:1 disordered parent structure of symmetry
Pmcn
,
Z
= 4 (
a
′ =
a
/2,
b
′ =
b
/2,
c
′ =
c
), in which the mirror imposes a 1:1 disorder on two-dimensionally polymeric layers perpendicular to
a
*. An ideally ordered structure has monoclinic space group
C
112
1
/
d
(
P
2
1
/
c
using an alternative axis system
b
,
c
, [
a
+
b
]/2), but may also be described as two inversion-related substructures of
Cmc
2
1
pseudo- symmetry, where the
b
-glide planes of one substructure coincide with the mirror planes of the other and
vice versa
. Moving one substructure by
b
/2 relative to the other creates a different orientation of the structure. The crystal studied showed a partial disorder of each substructure relative to origins
b
/2 apart [0.964 (4):0.036 for one substructure and 0.584 (3):0.416 for the other]. This lowers the symmetry of the average structure to
C
112
1
with intensities realistically described as
K
2
[(1−\delta)|
F
(
hkl
)|
2
+ \delta|
F
(
hkl
)|
2
], where
K
2
for
h
odd,
k
odd reflections is 0.444 (7) of the value for
h
even,
k
even reflections, \delta is 0.325 (5) and
F
(
hkl
) is the structure factor for an ideally ordered structure. Final values for
R
of 0.046 and 0.090 were obtained for the 844 
h
even,
k
even and 687 
h
odd,
k
odd reflections with
I
(
h
) > 3\sigma(
I
(
h
)) used in refinement. A bond-valence interpretation of the bonding within the polymeric layer structure is given.