Fluoride bridges

Iron(III) fluoride ttihydrate [15469-38-2] FeF3-3H2 0, crystallizes from 40% HF solution ia two possible crystalline forms. At low temperature the a-form, which is isostmctural with a-AlF 3H2O, is favored. High temperatures favor P-FeF 3H2O, the stmcture of which consists of fluoride-bridged octahedra with one water of hydration per unit cell. 

In nitrate media ( 6 Af), fluoride ion has a catalytic effect on the exchange reaction between Ce(IV) and Ce(III). Hornig and Libby have made a detailed study of this effect, over the range of added KF, 0 to 8.4 x 10 M, and have concluded that a pathway involving a monofluoro complex occurs, possibly involving a fluoride-bridged activated complex. 

The CSD revealed only one example of the fluoride-bridged dimeric Zn2F2, analogous to the commonly observed unit for the other halides. The compound characterized by Roesky and co-workers is the only structure known with fluoride-bridged zinc atoms.646 Maggard et al. show a bridging fluoride between a molybdenum(V) and the zinc center in a coordination... 

The structure of the tetramer is complex and involves fluoride bridges, as do the hexamers that exist in... 

Using the octafluorotolyl substituents, chains of doubly fluoride-bridged dimers are formed. Fluorine atoms in ortho-position of the aryl substituents contribute to tellurium coordination through intramolecular F- -Te contacts in the range of 320-330 pm.107... 

Formula AuFs MW 253.96 fluoride bridge structure consisting of AuF4 units. 

The oxotetrafluoride CrOF4 is an easily hydrolyzed solid obtained as a by-product when fluorine is passed over chromium,1365 but it is better prepared from Cr03 as just outlined. It is a powerful fluorinating and oxidizing agent, is fluoride bridged in the solid state, molecular (C ) in a low temperature matrix, and forms the salt Cs[CrOF5] (Table 111).1366... 

Xenon fluorides can also act as fluoride ion donors. Strong Lewis acids react with xenon fluorides to yield the expected compounds, but since both the ealiome and anionic species can form fluoride bridges, the stoichiometries may appear strange at limes ... 

Dimethylpyrazole (L) has been shown to react with Cd(BF4)2 to give CdL2F2 containing a linear fluoride-bridged chain structure with L completing an octahedral coordination for the Cd.446... 

Stable dialkyl ether poly(hydrogen fluoride) complexes (R20-[HF]n, R = Me, Et, n-Pr) have recently been developed by Prakash, Olah, and colleagues.33 DFT calculations suggest a cyclic poly(hydrogen fluoride) bridged structure. Dimethyl ether-5 HF (DMEPHF) was shown to be a convenient and effective fluorinating agent (see Section 5.10.1). 

It is claimed that addition of catalytic quantities of a quaternary ammonium salt greatly enhances both reactivity and yield [48] in the formation and subsequent reactions of (58). Tertiary fluorinated carbanions, generated from corresponding unsaturated precursors, react with a variety of electrophiles [46, 49,50] (Scheme 25), the most surprising being with fluorocarbon iodides, to give remarkable fluoride-bridged products, e. g. (60) [47],... 

Recently Pagenkopf and Carreira reported that the addition of trimethyl aluminum to aldehydes can be catalyzed by the putative difluorotitanium-TADDOLate 29, giving secondary alcohols 30 of moderate enantiomerical purity (Scheme 4) [14]. In accordance with structural studies by Roesky, Noltemeyer, and co-workers [15] a fluoride bridging titanium and aluminum is postulated for the transition state. 

The tetrafluoride is an unstable blue solid that decomposes to MnF3 + F2. Both this fluoride and MnF3 form adducts with SbF5 that are non-ionic with fluoride bridges.31... 

Gold IIT) fluoride is best made by fluorination of Au2C1 at 300°C and forms orange crystals, which decompose to the metal at 500°C. It has a unique structure with square AuF4 units linked into a chain by cis fluoride bridges the F atoms of adjacent chains interact weakly with the axial sites. 

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