Affiliation:
1. Institut für anorganische Chemie der Christian-Albrechts-Universität Kiel
Abstract
Abstract
The electronic absorption spectra of the solid tetramethylammonium salts of [IrFnC6-n]2-, n=1-5, including the stereoisomers for n = 2, 3, 4, were measured in KCl pellets at 10 K, the electronic Raman spectra (ER) on rotating samples of the pure complex salts at 80 K. The strong bands in the UV/VIS region are assigned as charge-transfer transitions from σ(t1u), π(t1g, t1u, t2u) Cl orbitals into the π (t5
2g) Ir(IV) level. The observed splittings and shifts are interpreted by qualitative MO treatment "according to the point groups D4h, C4v, C3v and C2v of the mixed ligand complexes. Two week bands in the NIR region between 1650 and 2000 nm are assigned to intraconfigurational transitions within the 2T2g(Oh) ground term, split by spinorbit coupling (5000-6000 cm-1) and lowered symmetry (30-110 cm-1) into three Kramers doubletts. The assignment of the O-O transitions is confirmed by stronger bands at the same frequencies in the ER spectra. They are coupling preferably with odd vibration modes in the absorption and with even modes in the ER spectra. The hypsochromic shift of the d-d-bands corresponds with the increase of the relativistic nephelauxetic ratio β* from 0.75 to 0.90 and indicates the loss of covalency with increasing number of F ligands.
Subject
Physical and Theoretical Chemistry,General Physics and Astronomy,Mathematical Physics
Cited by
9 articles.
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