Abstract
Interaction of robust chromium(III) fluoride complexes with sodium or lithium cations in solution lead to hypsochromic spectral shifts of increasing magnitude along the series: trans-[CrF2(py)(4)](+), mer-[CrF3(terpy)], and fac-[CrF3(Me(3)tacn)]. Crystalline products isolated from solution exhibit mu(2)-bridging by the fluoride ligands in a linear fashion between Na+-ions and chromium centres in catena-[Na(H2O)(4)(mu-F)-trans-{CrF(py)(4))](HCO3)(2) and in the dimers [Li(H2O)(n)(mu-F)-trans-{CrF(py)(4))}](2+) (n = 3, 4). The uncharged chromium complexes fac-[CrF3(Me(3)tacn)] and mer-[CrF3(terpy)] have been synthesized from mer-[CrF3(py)(3)] and shown to precipitate sodium salts from solution, of which 3[CrF3(Me(3-)tacn)]center dot 2Na(Bph(4)).solv and 6[CrF3(terpy)]center dot 4Na(Bph(4)).solv have been crystallographically characterized. In these clusters, the neutral fluoride complexes bring the Na+ cation separation down to 3.610 angstrom and 3.369 angstrom, respectively, which is much closer than the inter-cation distance in NaCl and comparable to that of NaF. DFT calculations support the notion of a strong interaction between Na+ ions and neutral chromium(III) fluoride complexes. The calculations reproduce the magnitude and the counter-intuitive sign of the spectral shifts induced by second sphere complexation in solution, which originates in a breakdown of the assumption of parameter transferability in ligand-field descriptions. (C) 2010 Elsevier B.V. All rights reserved
| Original language | English |
|---|---|
| Journal | Journal of Fluorine Chemistry |
| Volume | 131 |
| Issue number | 9 |
| Pages (from-to) | 898-906 |
| Number of pages | 9 |
| ISSN | 0022-1139 |
| DOIs | |
| Publication status | Published - 2010 |
Keywords
- Bridging
- Cr(III)
- Robust
- Linear
- Chain
- FIELD ABSORPTION-BANDS
- RAY CRYSTAL-STRUCTURE
- NMR-SPECTRA
- SOLID-STATE
- ANIONS
- SOLVATOCHROMISM
- TITANIUM(III)
- PYRIDINE
- ENERGY
- APPROXIMATION