Fluorofosgene – Wikipedia

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The fluorofosgene O Carbonile fluoride , by Formula Cof 2 , is an colorless, hygroscopic, extremely aggressive, toxic gas and equipped with a pungent smell. [first] It is part of the carbon ossalogenures, [2] Where the C is in its maximum state of oxidation (+4), and it is the analogous compound of Fosgene, with fluorine (more electronagative) instead of chlorine. It is a very stable thermodynamically stable mixture (δ H ƒ ° = -638, kJ / times), [3] But also very reactive: with water, but also only with the humidity of the air in the gaseous phase, [4] It quickly hydrizes by giving carbon dioxide at the end and fluorideous acid. [5]

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The fluorophoscene molecule is qualitatively very similar to that of Fosgene: it is trigonal planare, with the central hybridized carbon sp 2 , but molecular symmetry is C 2V only (not D 3H , as in the bf isoelectronic species 3 or the carbonate ion co 3 2- ): [6] In addition to the fact that the three atoms around the central atom are not the same, the corners also differ from the normal value of 120 °. Despite being the carbon atom linked to very electronegative atoms, the molecule is not very polar ( m = 0.95 d), because the moments of dipole of the ties, which are directed towards the leaders of a triangle, tend to escape their vector sum.

The Carbonile fluoride molecule can be considered a resonance hybrid between the three following limit forms, even if each of the last two (equal to each other) contributes very limited to the structure of the royal molecule, because it contains a separation of unfavorable charge: [7] [8]

[ F 2 C=O ←→ + F=C(–F)–O – ←→ F–C(–O – )=F + ]

From combined investigations of electronic diffraction and rotational spectroscopy in the microwave region the following structural parameters were found: [9]

r (C = o)) = 117,17 pm; r (C–F) = 131,57 pm
∠(FCF) = 107,71°; ∠(FCO) = 126,15°

The bond C = O in COF 2 It is significantly shorter than that in Acetone (121.5 pm [ten] ) and in formaldehyde (120.78 pm [11] ), and is just lower than the one in COCL 2 (117,7 pm [twelfth] ). The C – F binding is also a little shorter than normal, i.e. 135 prosecutors per c ( sp 3 )-F( sp 3 ), [13] but not so much, considering hybridization sp 2 carbon that tends to shorten the bond.

The FCF corner is much closer than the expected value of 120 ° for hybridization sp 2 of the central atom. Two factors operating in the same sense contribute to this result: VSEPR theory, [14] [15] which provides that a double bond occurs more angular space than a simple bond (therefore ∠ (FCF) <∠ (FCO)) and the rule of Bent, [16] [17] which provides for the use, by an atom (here c) which is linked to a more electronagative one of another (here f compared to O), of an orbital hybrid having less character s of the other, which therefore entails a narrowing of the corner between ties with fluorine (FCF) with respect to the theoretical value of 120 ° and the consequent enlargement of the other two (FCO), as is observed here.

A similar trend for the XCX corner is observed in COCL 2 (111.91 ° [twelfth] ) and also in 1.2-Difluoroetene H 2 C=CF 2 , where the FCF corner is still a little narrower (109.1 °); [18] also in the Methilene Fluoruro ch ch 2 F 2 , without double bonds, the FCF corner (108.49 °) is slightly smaller than the theoretical value of 109.5 °. [19]

Ionian chemistry in the gaseous phase [ change | Modifica Wikitesto ]

The CF molecule 2 Or has an ionization energy of 13.04 EV, [20] significantly greater than that of Cocl 2 (~ 11,2 ev). [21]

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The proton affinity of the Carbonile fluoride, which is a measure of its intrinsic basicity, is equal to 666.7 kj/mol: [22]

F 2 C=O (g) + H + (g) → [ F 2 C=O + –H ←→ F 2 C + –O–H ←→ + F=CF–O–H [23] ] (g)

As can be seen, this value of the proton affinity is intermediate among those of the water (691 kJ/mol [24] ) or of the aldehyde ant (712.9 kj/mol [22] ), which are more basic, and those of carbon dioxide (540.5 kJ/mol) or carbon tetrafluoride (529.3 kJ/mol [25] ), which are less basic. [26]

According to quotomccanici calculations, in the molecular ion which is produced (F 2 C=O · H + ) the proton joins the oxygen atom, [27] thus generating a stabilized structure by resonance with four limit forms.

Carbonile fluoride in the gaseous phase can behave from Lewis acid towards halogen and pseudo -deception anions: [28]

F 2 C=O (g) + F – (g) → [F 3 C–O – ] (g) D H ° = -178 KJ / times
F 2 C=O (g) + Cl – (g) → [F 2 Clc -o – ] (g) D H ° = -52.3 kj / times
F 2 C=O (g) + C≡n – (g) → [F 2 (N≡C)C–O – ] (g) D H ° = -98.3 kj / times

Industry, fluorofoscene is produced by reacting the fluorine and carbon monoxide in a non -catalytic reactor. The synthesis reaction consists of a combustion of carbon monoxide in which the oxygen is replaced, as a combustion, by the fluorine [29] .

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