Electronic spectra of the hexafluoroosmate(V) and hexafluoroiridate(V) anions

Abstract

The electronic spectra of the hexafluoroosmate(V) and hexafluoroiridate(V) anions have been studied by diffuse reflectance between 4 and 50 kK. For OsFe-the relatively weak bands at 8. 00, 10.3, 10.8, 16.3, and 18.2 kK are ascribed to formally spin-forbidden transitions within the tsg3 manifold, while a much stronger band at 37.5 kK, with a shoulder at 41.7 kK, is thought to involve both 4Aig -4Tzg and 4A8g -* 4Tig, tzg3 -* t2g2eg excitations, as well as a Laporte-allowed charge-transfer transition. For IrFe-the absorption at about 4 kK and the well-marked peak at 6.5 kK are assigned to transitions within the spin-orbit split 3Tig(t2g4) ground state, and the weaker bands at 12.9 and 19.8 kK to spin-forbidden transitions within the t2g4 subshell. The weak band at 24.1 kK is attributed to the 3Tig(t2g4) -5Eg(t2g3eg) transition, and the fairly strong shoulder at about 33 kK to spin-allowed t2g4 -* Í2gseg excitations. It seems likely that the strong band with a maximum at 41.8 kK contains both charge-transfer and further t2g4 -»t2gseg transitions, The bands were fitted using the complete strongfield electrostatic and spin-orbit matrices for d3 and d4 systems, assuming C/B = 4.75 and 4.90 for Os(V) and Ir(V), respectively, yielding for OsFe-the parameters Dq = 3500 cm-1, B = 410 cm-1, and -3200 cm-1 and for IrF6the values Dq = 2850 cm-1, B -360 cm-1, and { = 3400 cm-1. The degree of covalency indicated is high for fluoride complexes and comparable with that found for quadrivalent MFe2-species of the 3d series.

Insights into the Spin–Orbital Entanglement in Complex Iridium Oxides from High-Field ESR Spectroscopy

“…With the SOC constant ≈ 0.5 eV [57], the energy difference between the t 2g and e g orbital states ≈ 3.2 eV [38], and with g right = 1.49, Eq. ( 9) yields a significantly reduced value of the covalency reduction factor k = 0.4 , as is generally expected for 5d elements in a high oxidation state covalently bonded to the ligands (see, e.g., [58][59][60]).…”

Synthesis, structure, redox and spectra of green iridium complexes of tridentate azo-aromatic ligands

“…Such low energy transitions in iridium(III) complexes are uncommon. 22,23 To gain some insight into the nature of these transitions we have performed extended Hückel MO calculations with the crystallographic parameters of [Ir(L 1a ) 2 ]ClO 4 using the CACAO programme 24 by Mealli and Proserpio. Due to obvious limitations, we note that the results are qualitative in nature.…”

Unraveling the nature of magnetism of the 5$\boldsymbol{d^4}$ double perovskite Ba$_2$YIrO$_6$

“…A substantially larger negative g shift of −0.51 of the g right signal can be consistently explained by a combined effect of a much stronger spin-orbit coupling in 5d Ir as compared to a 3d ion and the counteracting effect of the strongly covalent character of Ir -O bonds of the highly oxidized Ir 6+ [38]. Indeed, with λ ≈ 0.5 eV [39], ∆ ≈ 3.2 eV [38], and g right = 1.49, one obtains from (3) a rather small value of k = 0.4 as is generally expected for 5d elements in a high oxidation state (see, e.g., [40][41][42]). The S = 1/2 ESR line g mid is characterized by a smaller but still a significant negative shift of the g factor from g s = 2.…”