Darstellung und spektroskopische Charakterisierung von Fluoro‐Chloro‐Iridaten(V)

Abstract

Bei der vorsichtigen Oxydation der reinen Fluoro‐Chloro‐Iridate(IV) mit BrF3 in Dichlormethan entstehen ohne Austausch von Cl‐Liganden die entsprechenden fünfwertigen Komplexe [IrF5Cl]−, cis‐[IrF4Cl2]− und fac‐[IrF3Cl3]‐. Die Schwingungsspektren dieser Gemischtligandkomplexe werden entsprechend den Punktgruppen C4v, C2v und C3v zugeordnet. Die größere Bindungsfestigkeit im Vergleich mit den entsprechenden IrIV‐Verbindungen zeigt sich in einer deutlichen Verschiebung der Banden zu höherer Energie um etwa 5–15%. Die anomalen Intensitäten einiger Ra‐aktiver Grundschwingungen lassen sich auf den Resonanz‐Raman‐Effekt zurückführen. Die elektronischen Absorptionsspektren werden an den festen Tetraethylammoniumsalzen der Fluoro‐Chloro‐Iridate(V) bei 10 K gemessen. Die intensiven Banden im UV/VIS‐Spektralbereich werden Charge‐Transfer‐Übergängen aus π(t1u, t2u) und σ(t1u) Orbitalen an Cl‐Liganden in das π(t 2g4)IrV‐Niveau zugeordnet. Die Intrakonfigurationsübergänge innerhalb der t 2g4‐Konfiguration von IrV sind durch Spin‐Bahn‐Kopplung und Symmetrieerniedrigung aufgespalten, man beobachtet sie in den Bereichen 3000, 5100–6400, 10900–13000 und 18 200 cm−1. Die OO‐Übergänge ergeben sich aus der Analyse der Schwingungsfeinstruktur; in einigen Fällen werden sie durch elektronische Raman‐Banden bestätigt. Mit zunehmender Anzahl der F‐Liganden verschieben sich alle Absorptionsbanden systematisch zu höheren Energien.

Preparation and Spectroscopic Investigations of Mixed Octahedral Complexes and Clusters

“…Similar investigations, sometimes supported by crystal structure determinations, have been performed on many series of the fluorochloro metalates [MF n Cl 6 - n ] z - of Ta(V), Os(IV), Os(V), Ir(IV), Ir(V), , and Pt(IV), fluorobromoosmates(IV), , chlorobromometalates [MCl n Br 6 - n ] z - of Nb(V), Ta(V), Tc(IV), Ru(IV), Rh(III), Os(IV), , Ir(III), Ir(IV), and Pt(IV), ,− bromoiodometalates [MBr n I 6 - n ] 2- of Re(IV), and Os(IV) , and the unique chloroiodo series [OsCl n I 6 - n ] 2- . , …”

“…However, distinctly long progressions of overtones on two LMCT bands of the tetramethylammonium (TMA) salt trans -(TMA) 2 [IrF 2 Cl 4 ] are present, which have been assigned by taking account of spin orbit coupling . Similar fine structures have been observed on the Ir(V) complexes, (TEA)[IrF 5 Cl] and cis -(TEA)[IrF 4 Cl 2 ], diluted as mixed crystals with nonreducing (TEA)[OsF 6 ], which has been chosen because it is transparent in the LMCT region …”

“…The postulated stereospecific formation of fac -K 2 [PtF 3 Cl 3 ] as the sole oxidation product of K 2 [PtCl 6 ] with BrF 3 has never been verified. , Depending on the reaction conditions, other mixed species [PtF n Cl 6 - n ] 2- have been detected; however, for n = 2, 3, 4, only the cis/fac isomers have been present . Corresponding fluorochloro complexes are known for Re(IV,V), Os(IV,V), and Ir(IV,V). − Octahedral complexes containing the heavier halides, Br or I, together with F are rare, but are known for Pt(IV) and Os(IV), ,, and most notably Re(IV), for which there are many examples of 3-fold mixed species …”

“…In addition to the complete series, [OsF n Cl 6 - n ] 2- , n = 0−6, with the central metal ion in the d 4 configuration, LMCT spectra from the corresponding d 3 complexes of Os(V) and d 5 complexes of Ir(IV), and even some species from the d 4 Ir(V) system have been recorded . Spectra of analogous complexes from the different series are essentially similar, although resolution is of a different quality, and there are no vibronic fine structures in the spectra within the Os(IV) and Os(V) series.…”

Dipyridiniomethane cis- and trans-Difluorotetrachloroosmate(IV), cis- and trans-[(C5H5N)2CH2][OsCl4F2]

“…Octahedrally coordinated complexes of the type [mFnCl6_n] 2-(M = Os, Ir, Pt; n = 0-6) have been synthesized systematically via stereospecific substitution reactions and characterized using vibrational and NMR spectroscopy to examine bond interactions due to the mutual trans influence of F and C1 (Preetz, Ruf & Tensfeldt, 1984;Groth & Preetz, 1987;Alyoubi, Greenslade, Foster & Preetz, 1990;Parzich, Peters & Preetz, 1993). However, the trans influence on bond distances in mixed halogeno complexes had not been studied extensively until recently because of statistical disorder of the ligands in high-symmetry AzB lattices with alkali metal or spherical alkylammonium cations (Keller & Homborg, 1976).…”