The metal-rich palladium chalcogenides Pd{sub 2}MCh{sub 2} (M=Fe, Co, Ni; Ch=Se, Te): Crystal structure and topology of the electron density
- Department Chemie und Biochemie der Ludwig-Maximilians-Universitaet Muenchen, Butenandtstr. 5-13 (Haus D), D-81377 Munich (Germany)
Crystals of Pd{sub 2}MCh{sub 2} (M=Fe, Co, Ni; Ch=Se, Te) were synthesized by heating the elements at 823-1323K in silica ampoules under argon atmosphere. Their structures were determined by single-crystal X-ray diffraction at room temperature. The metallic compounds crystallize in a variant of the K{sub 2}ZnO{sub 2} type (Ibam, Z=4, Pd{sub 2}CoSe{sub 2}: a=5.993(1), b=10.493(2), c=5.003(1) A; Pd{sub 2}FeSe{sub 2}: a=5.960(1), b=10.576(2), c=5.078(1) A; Pd{sub 2}CoTe{sub 2}: a=6.305(1), b=11.100(2), c=5.234(1) A; Pd{sub 2}NiTe{sub 2}: a=6.286(1), b=11.194(2), c=5.157(1) A). One-dimensional {sub {approx}}{sup 1}[MCh{sub 4/2}] tetrahedra chains with remarkably short M-M bonds run along [001], separated by [Pd{sub 2}] dumbbells with palladium in fivefold coordination of selenium or tellurium atoms. The structure may also be described as a filled variant of the SiS{sub 2} type. M atoms occupy 14 of the tetrahedral voids and the Pd atoms fill all octahedral voids in a distorted ccp motif of chalcogen atoms. Even though the Pd{sub 2}MCh{sub 2} compounds are isotypic to K{sub 2}ZnO{sub 2} from the crystallographic viewpoint, we find a different bonding situation with additional homo- and heteronuclear metal-metal bonds between the Pd and Co atoms. The electronic structures and topologies of the electron densities of Pd{sub 2}CoSe{sub 2} and isotypic Na{sub 2}CoSe{sub 2} are analyzed and compared by using Bader's AIM theory. Different values of topological charge transfer and electron density flatness indices uncover striking quantitative differences in the nature of chemical bonding between the metallic compound Pd{sub 2}CoSe{sub 2} and nonmetallic Na{sub 2}CoSe{sub 2}.
- OSTI ID:
- 21015637
- Journal Information:
- Journal of Solid State Chemistry, Vol. 180, Issue 1; Other Information: DOI: 10.1016/j.jssc.2006.09.028; PII: S0022-4596(06)00537-8; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ARGON
CHEMICAL BONDS
COBALT COMPOUNDS
CRYSTALLOGRAPHY
ELECTRON DENSITY
ELECTRONIC STRUCTURE
HEATING
IRON COMPOUNDS
MONOCRYSTALS
ORTHORHOMBIC LATTICES
PALLADIUM COMPOUNDS
SELENIDES
SILICA
TELLURIDES
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 1000-4000 K
TOPOLOGY
VOIDS
X-RAY DIFFRACTION