Tin IV Fluoride

In the same way as described for TiF (page 250), SnCl is added dropwise to double the theoretical amount of anhydrous HF, 

Snow-white, starlike crystal clumps extremely hygroscopic dissolves in water with v orous fizzing. 

Small portions of nitrate- and acetate-free PbCOa are added to hydrofluoric acid contained in a Pb or Pt dish. The HF must be present in excess. The mixture is heated for about one day until CC ceases to evolve. The excess of acid is then decanted and the residue evaporated to dryness on a hotplate. The product is then rapidly melted by placing the Pt dish for a few minutes in an electric furnace which is preheated to red heat. The lead hydrofluoride is thereby decomposed. 

Because of its impurities, this PbO is less suitable as a starting material for PbFg than Pb(OH)3. 

White crystalline powder. Dimorphous rhombic a-PbFg (lead chloride type) changes above 316°C into cubic yS-PbFg (fluorite type). 

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Tri-n-butyl-tin(IV) fluoride, cetyltrimethylammoniumbromide, cationic, anionic, and non-ionic surfactants... 

PROBLEM What are the chemical formulas for tin(IV) fluoride and lead(IV) oxide ... 

Solution Using the crisscross method, tin(IV) fluoride will be SnF4. When using the crisscross method for lead(IV) oxide, initially the formula will look like Pb204 but remembering that all ionic compounds are written in the lowest ratios, the real formula is Pb02. 

In 1956, it was reported that heating equimolar quantities of phosgene and calcium fluoride at 500 C in a steel bomb gives CF (1%), CCIF3 (65%), CCl Fj (30%), CCI3F (5%), a trace of CCl, and some COFj and COCIF the formation of the fluoromethanes is promoted by the presence of aluminium(ni) fluoride, tin(IV) fluoride, iron(III) fluoride or antimony(V) chloride [1454] ... 

The actual catalyst is believed to be a complex (A) of the three components since it is soluble in CH2CI2 even though none of the components is. The amine-coordinated tin(ll) triflatc acts as a lewis acid to activate the aldehyde, and the tin(IV) fluoride or acetate interacts with the silyl enol ether. 

The importance of the combination of chiral diamine-coordinated tin(II) triflate and tributyltin fluoride is obvious from the result that no enantiomeric selection was observed when using only chiral diamine-coordinated tin(II) triflate or a combination with other metal salts. Tributyltin fluoride was found to be the most effective among the several tin(IV) fluorides examined. The maximum ee was obtained (92%) when (S)-l-methyl-2[(iV-l-naphthylamino)methyl]pyrro-lidine (19) was employed as the chiral diamine. 

Stannane reacts with boron trifluoride to form tin(IV) fluoride quantitatively. 

Tin(IV) fluoride may be prepared by the action of anhydrous hydrogen fluoride upon tin(IV) chlorideis2. it is an extremely hygroscopic white crystalline solid which may be sublimed at about 700°. Although it is likely that gaseous SnF4 has tetrahedral molecules with four-coordinate tin, solid SnF4 differs markedly from the other three tin(IV) halides... 

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