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Palladium Compounds with +III Oxidation State
Author(s) -
Tressaud A.,
Khairoun S.,
Dance J. M.,
Hagenmuller P.
Publication year - 1984
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.19845171003
Subject(s) - tetragonal crystal system , orthorhombic crystal system , crystallography , palladium , octahedron , chemistry , ground state , paramagnetism , phase (matter) , jahn–teller effect , alkali metal , transition metal , materials science , crystal structure , condensed matter physics , physics , catalysis , atomic physics , ion , organic chemistry
Abstract Trivalent oxidation state of palladium has been unambiguously characterized in elpasolites of A 2 BPdF 6 formulation (A, B = alkali metal). At room temperature K 2 LiPdF 6 is cubic (Fm3m space group, a = 8.154 Å) while all other A 2 BPdF 6 compounds possess a tetragonal F4/mmm symmetry with c/a > 1. Phase transitions in Pd elpasolites have been followed using low‐and hightemperature X‐ray diffraction. Between 200 and 500 K every A 2 BPdF 6 compound undergoes a tetragonal ⇄ cubic phase transition. The ESR signals are characteristic of a doublet ground state; they bring up the unequivocal evidence of a t 2g 6 e g 1configuration of Pd(+III). This configuration is stabilized versus the t 2g 5 e g 2high ‐spin alternative by an important Jahn‐Teller splitting of the 2 E g ‐state. ESR results confirm that the PdF 6 octahedra are tetragonally elongated in most cases; an additional orthorhombic component is found for Cs 2 KPdF 6 and Cs 2 RbPdF 6 . The occurence of Pd(+III) in a low‐spin state is corroborated by magnetic measurements.