Fluorine ionic radius

Shannon and Prewitt base their effective ionic radii on the assumption that the ionic radius of O2- (CN 6) is 140 pm and that of F (CN 6) is 133 pm. Also taken into consideration is the coordination number (CN) and electronic spin state (HS and LS, high spin and low spin) of first-row transition metal ions. These radii are empirical and include effects of covalence in specific metal-oxygen or metal-fluorine bonds. Older crystal ionic radii were based on the radius of F (CN 6) equal to 119 pm these radii are 14-18 percent larger than the effective ionic radii. 

Small ionic radius of fluorine—> low polarizability of C—F bond... 

For our purpose, the most interesting result in Table 2 is the separation 3 to 8 eV spreading out each of the two a sets in each of the two molecules. It cannot be excluded that this effect contains a contribution from preferential interaction with C 2 s or C 2 p, or with S 3 s compared with S 3 p and the high-lying S 3 d. However, the main reason seems to be inter-ligand repulsion. The overlap integral (62) between two 2 s orbitals of adjacent fluorine ligands is close to 0.11 in CF4 and 0.05 in SF6 compatible with the observed / differences. It may be noted that the F—F distances in these two particular molecules are considerably shorter than twice the ionic radius of F in... 

The reaction (1) shows that fluorine severely catalyses hydrolysis reaction [3]. In the hydrolysis reaction, because of the smaller ionic radius of the fluorine, which approaches a molecule of TEOS in the solution forming a highly unstable pentacovalent activated intermediate. This complex rapidly decomposes, forming a partially fluorinated and hydroxylated silicon alkoxide. 

At least in compounds with metals of lower oxidation states up to three or four, the metal-fluorine bond is almost purely ionic and the small, least polarizable fluoride ion behaves as a small hard sphere with an ionic radius which varies, depending on the coordination number, between 1.285 (CN 2) and 1.320 A (CN 6). The structures of fluorides are therefore determined mainly by simple geometrical and electrostatic principles, such as sphere packing, the rigid sphere concept, which allows derivation of the coordination number around... 

Gas chromatographic studies of ethers, ketones, alcohols, esters, olefins, and alkanes, using columns with liquid phases containing P-diketonate complexes in squalane, revealed that the more nucleophilic organic substrates reacted more strongly with the P-diketonates than the less basic ones. Er complexes of fluorinated P-diketones (especially 3-trifluoroacetyl-d-camphor-ate, facam) reacted more strongly with these nucleophiles than did similar non-fluorinated Er complexes. The retention time of THE increased exponentially with the inverse of metal ionic radius in the facam chelates of a variety... 

In Table 1.1 we have collected some atomic and nuclear properties of the halogens, fluorine being included for completeness and comparison. To stress the ambiguity of some properties such as electronegativity and ionic radius we have listed values from different authors - the original articles should be consulted for an account of the underlying criteria and definitions. 

The foregoing discussion has been based on the relative sizes of cations and anions. A closely parallel discussion could be presented based on covalent bond radii and van der Waals radii of atoms (Section 6-15). The van der Waals radius of the fluorine atom, 135 pm (Table 6-6), is nearly equal to the ionic radius of the fluoride ion, 136 pm, and the sums of covalent radii are approximately equal to the corresponding sums of ionic radii. 

For an example of fluorine-free polyether ligands used to successfully prevent oligomerization of barium complexes (particularly problematic for heavy Group 11 complexes due to the large ionic radius... 

The acid character of the lanthanide chelate and the donor and steric properties of the substrate define the strength of the acid-base adduct. Usually more stable complexes are found as the ionic radius of the metal decreases. Fluorinated diketonates increase the Lewis acidity of the lanthanide ion with respect to the protonated derivatives. This explains why Eu(fod)3 (see Table 1) is the mostly commonly used LSR. 

The stabilization of Ca " " and F ions into the Ce-based oxides adopting a fluorite-type structure with nanosized particles can then be explained. In many cases, alkaUne or alkaline earth as well as fluorine are excellent sintering agents, which contribute to the particle growth. In the Cei xCax02 x and Cei /Ca/02-x y/2 y series, the particle size does not increase and remains around 10 nm. The electronegativity, formal charge and ionic radius are quite different for Ce " and Ca + ions as those of and F anions. Ca ... 

In the case of fluorinated compounds, the F ionic radius in a tetrahedral coordination is always lower than one of ion rp- = 1.31 In Cap2, considering a cubic close... 

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