[SnI8 {Fe(CO)4 }4 ]2+ : Highly Coordinated Sn+II I8 Subunit with Fragile Carbonyl Clips

Angew Chem Int Ed Engl. 2020 Mar 27;59(14):5510-5514. doi: 10.1002/anie.201911126. Epub 2020 Jan 23.

Abstract

[SnI8 {Fe(CO)4 }4 ][Al2 Cl7 ]2 contains the [SnI8 {Fe(CO)4 }4 ]2+ cation with an unprecedented highly coordinated, bicapped SnI8 prism. Given the eightfold coordination with the most voluminous stable halide, it is all the more surprising that this SnI8 arrangement is surrounded only by fragile Fe(CO)4 groups in a clip-like fashion. Inspite of a predominantly ionic bonding situation in [SnI8 {Fe(CO)4 }4 ]2+ , the I- ⋅⋅⋅I- distances are considerably shortened (down to 371 pm) and significantly less than the van der Waals distance (420 pm). The title compound is characterized by single-crystal structure analysis, spectroscopic methods (EDXS, FTIR, Raman, UV/Vis, Mössbauer), thermogravimetry, and density functional theory methods.

Keywords: SnI8; carbonyl ligands; ionic liquids; tin iodide.