COORDINATION CHEMISTRY WITH CF UNITS AS SIGMA-DONOR - AG-ETHERS WITH DIRECT METAL-FLUORINE INTERACTIONS( COMPLEXES OF PARTIALLY FLUORINATEDCROWN)

The partially fluorinated cryptands FN2O4 and BenzoFN(2)O(4), which ar e relatives of the [2.2.1]cryptand, were synthesized in good yields fr om 1,3-bis(bromomethyl)-2-fluorobenzene and diaza-18-crown-6 or benzod iaza-18-crown-6, respectively. These macrobicyclic ligands form very s table complexes with Ag(I) salts, and it was shown that close fluorine -silver interactions occur in solution as well as in the solid state. Numerous experimental evidence for this is available: NMR competition experiments show that Ag+ complexes of FN2O4 are significantly more st able than those of HN2O4 (the two Ligands are identical except that on e fluorine atom is replaced by one hydrogen atom in HN2O4); the (1)J(C F) coupling constants of Ag+. FN2O4 and Ag+. BenzoFN(2)O(4) are reduce d by 10 Hz compared to those of the respective free ligands FN2O4 ((1) J(CF)=253 Hz) and BenzoFN(2)O(4). ((1)J(CF)=252 Hz). The X-ray crystal structure of Ag+. FN2O4 reveals short Ag+-F distances [271.4(3) pm]; coupling of the Ag-107.109(+) and F-19 nuclei is observed in the F-19- NMR spectra (J=24 Hz for Ag+. FN2O4, J=25 Hz for Ag+. BenzoFN(2)O(4)). The H-1-NMR spectrum of Ag+. FN2O4 is very complex and exhibits sixte en unique proton resonances, whose evaluation yielded coupling constan ts and NOEs, which show that the structure in solution is compatible w ith the results obtained by the X-ray crystal structure determination.