Excited states of polonium(iv): electron correlation and spin–orbit coupling in the Po⁴⁺ free ion and in the bare and solvated [PoCl₅]⁻ and [PoCl₆]²⁻ complexes

Abstract

Polonium (Po, Z = 84) is a main-block element with poorly known physico-chemical properties. Not much information has been firmly acquired since its discovery by Marie and Pierre Curie in...

Unravelling the 6sp ← 6s absorption spectra of Bi(iii) complexes

“…The same approach provides λ = 6729 cm −1 for the free Bi( iii ) ion, in line with the expected reduction in λ in metal complexes compared with the free ion due to covalency. 34 We also note that for these complexes, the 3 P 0 and 3 P 1 levels show very similar energies and that the lowest-energy absorption is due to the 3 P 1 ← 1 S 0 transition. Thus, the higher energy of the 3 P 1 ← 1 S 0 transition calculated for [Bi(DMSO) 8 ] 3+ (260 nm) compared with [BiCl 6 ] 3− (315 nm) and [BiCl 5 ] 2− (326 nm) is not related to significant differences in the values of λ .…”

“…Studies performed on the Po( iv ) analogue evidenced that a better match of the absorption spectral data was found with a model where the complex holds a water molecule ([PoCl 5 (H 2 O)] − ). 34 However, calculations performed on the [BiCl 5 (H 2 O)] 2− system (using an implicit PCM solvation model) resulted in the expulsion of the water molecule from the inner-coordination sphere, with a calculated Bi⋯O distance of 2.754 Å. Thus, the lower oxidation state of the metal ion in the Bi( iii ) complex results in a weak interaction with the water ligand.…”

“…The energies of the 3 P 0 and 3 P 2 levels can be used to estimate the SOC constant λ using eqn (1) and (2), which can be combined to give eqn (3). 34 E ( 3 P 0 ) = E ( 3 P) − 2 λ E ( 3 P 2 ) = E ( 3 P) + λ λ = ( E ( 3 P 2 ) − E ( 3 P 0 ))/3…”

“…Indeed, square pyramidal coordination was predicted by computational studies performed on the isoelectronic [PoCl 5 ] − . 33,34 Furthermore, the 6s 2 lone pair in [BiCl 5 ] 2− is polarised by a small but significant p character (2.0% according to natural bond orbital analysis), while in [BiCl 6 ] 3− , the lone pair has 100% 6s character, according to natural bond orbital (NBO) analysis. Studies performed on the Po(IV) analogue evidenced that a better match of the absorption spectral data was found with a model where the complex holds a water molecule ([PoCl 5 (H 2 O)] − ).…”

“…The energies of the 3 P 0 and 3 P 2 levels can be used to estimate the SOC constant λ using eqn (1) and ( 2), which can be combined to give eqn (3). 34 Eð…”