Alkali metal cation complexation and solvent interactions by robust chromium(III) fluoride complexes

作者：Birk Torben; Magnussen Magnus J; Piligkos Stergios; Weihe Hogni; Holten Anders; Bendix Jesper^*

来源：Journal of Fluorine Chemistry, 2010, 131(9): 898-906.

DOI：10.1016/j.jfluchem.2010.06.003

• Bridging
• Cr(III)
• Robust
• Linear
• Chain

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-[CrF(2)(py)(4)](+), mer-[CrF(3)(terpy)], and fac-[CrF(3)(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(H(2)O)(4)(mu-F)-trans-{CrF(py)(4))](HCO(3))(2) and in the dimers [Li(H(2)O)(n)(mu-F)-trans-{CrF(py)(4))}](2+) (n = 3, 4). The uncharged chromium complexes fac-[CrF(3)(Me(3)tacn)] and mer-[CrF(3)(terpy)] have been synthesized from mer-[CrF(3)(py)(3)] and shown to precipitate sodium salts from solution, of which 3[CrF(3)(Me(3-)tacn)]center dot 2Na(Bph(4)).solv and 6[CrF(3)(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.

• 出版日期2010-9