Phosphorus pentachloride structure

However, phosphorus pentachloride in the solid state has an ionic lattice built up of (PC ) and (PClg)" ions and these ions are believed to exist in certain solvents. Thus under these conditions the maximum covalency is reached with chlorine. In phosphorus pentabromide, PBrj, the solid has the structure [PBr4] [Br] . 

Because of the structural requirements of the bielectrophile, fully aromatized heterocycles are usually not readily available by this procedure. The dithiocarbamate (159) reacted with oxalyl chloride to give the substituted thiazolidine-4,5-dione (160) (see Chapter 4.19), and the same reagent reacted with iV-alkylbenzamidine (161) at 100-140 °C to give the 1 -alkyl-2-phenylimidazole-4,5-dione (162) (see Chapter 4.08). Iminochlorides of oxalic acid also react with iV,iV-disubstituted thioureas in this case the 2-dialkylaminothiazolidine-2,4-dione bis-imides are obtained. Thiobenzamide generally forms linear adducts, but 2-thiazolines will form under suitable conditions (70TL3781). Phenyliminooxalic acid dichloride, prepared from oxalic acid, phosphorus pentachloride and aniline in benzene, likewise yielded thiazolidine derivatives on reaction with thioureas (71KGS471). 

The largest class of molecules to violate the octet rule consists of species in which the central atom is surrounded by more than four pairs of valence electrons. Typical molecules of this type are phosphorus pentachloride, PC15, and sulfur hexafluoride, SF6. The Lewis structures of these molecules are... 

The Lewis structure of the PCI, molecule is shown in (22), and we see that it obeys the octet rule. However, when phosphorus trichloride reacts with more chlorine (Fig. 2.10), phosphorus pentachloride, a pale yellow crystalline solid, is produced ... 

B. Reactions.—This year has seen the publication of a number of papers on the reactions of olefins and acetylenes with phosphorus pentachloride, to produce new phosphorus-carbon bonds. An investigation into the structural requirements of trisubstituted olefins (40) undergoing the above reaction has shown that both steric and electronic factors are important, e.g. an adduct forms with (40 X = CH3) but no reaction occurs for (40 X = Ph). Further examples of the reactions of unsaturated ethers include the formation and decomposition of adducts from a-methoxystyrene... 

Several papers have been devoted to the subject of reactions of phosphoranes with carboxylic acids and their derivatives. Thus triphenylphosphine dibromide (111) in acetonitrile cleaves lactones,93 while the corresponding dichloride (112) converts esters into acid chlorides.94 The reactions of esters with phosphorus pentachloride (101) have been studied further,95 and the influence of structural changes on the yields of products (113) and (114) has resulted in minor modifications to the mechanism previously96 outlined. 

Whilst the formation of thionyl chloride by the action of phosphorus pentachloride on an alkali sulphite favours a symmetrical structure for the latter, the interaction of an alkali sulphite with ethyl iodide, as mentioned already, is directly opposed to this evidence, as also is the production of sodium sulphite on reducing sodium dithionate with sodium.5 The remaining inorganic evidence is little more satisfactory. 

Exercise 16-31 Work out reasonable mechanisms for the reactions of phosphorus pentachloride and sulfur tetrafluoride with carbonyl groups. Both phosphorus and sulfur can accommodate five or more) bonded atoms, and the structure of phosphorus pentachloride in the solid state is [PCI4 ] [PCl60]. 

Exercise 30-6 Reduction of the ketone group of (—)-menthone, which has its alkyl groups trans to one another, gives two products, known as (—(-menthol and (+)-neomenthol. These two substances differ considerably in their reactions. (+)-Neomenthol undergoes dehydration either in methanoic acid or when treated with phosphorus pentachloride, whereas (—(-menthol gives a methanoate ester with methanoic acid and a chloride with phosphorus pentachloride. What is the relationship between neomenthol and menthol, and why do they behave differently with methanoic acid and phosphorus pentachloride What is the likely structure of the menthene from dehydration of neomenthol (Review Sections 8-8D, 12-3D, and 12-5.)... 

Phosphorus pentachloride is an ionic solid consisting of PC14+ cations and PC16 anions, and it sublimes at 160°C to a gas of PCI, molecules. The Lewis structures of the polyatomic ions and the molecule are shown in (33). Although the cation is a polyatomic ion in which the P atom does not need to expand its valence shell, in the anion the P atom has expanded its valence shell to 12 electrons, by making use of two of its 3d-orbitals. In PC15, the P atom has expanded its valence shell to 10 electrons by using one 3d-orbital. 

Solid phosphorus pentachloride exists as PC14+PC16. Write the Lewis structures for the two ions and predict their shapes from VSEPR theory. 

Draw an electron-dot structure for phosphorus pentachloride, PCI5. 

One of the earliest attempts to prepare analogues of FA as potential inhibitors involved the synthesis of 2-amino-4,7-dihydroxypteridine-6-carboxylyl-p-ami-nobenzoic acid (612) (in which the change from the structure of FA itself is exchange of the methylene bridge for a carbonyl group, and oxidation of position 7 to a lactam). This compound, which was a surprisingly effective inhibitor, was prepared from isoxanthopterin carboxylic acid (611) by in situ conversion to its acid chloride with a mixture of phosphorus oxychloride and phosphorus pentachloride, followed by addition of p-aminobenzoylglutamic acid (Scheme 3.132) [115]. 

In the gas phase, phosphorus pentachloride and pentabromide have the trigonal bipyramid structure (D3h symmetry),... 

The structure XXII for rhynehophylline has been confirmed, and the relative stereochemistry at C-15 and C-20 has been elucidated, by a total synthesis (80) of (+) JV-methylrhynchophyllane (XXVI) (Marion s N-methylisorhynchophyllane), which had been prepared earlier by methyl-ation of (iso)rhynchophyllane with sodium methoxide and methyl iodide (28). The lactone (XXVII) of threo-3,4-diethyl-5-hydroxyvaleric acid was converted by reaction with phosphorus pentachloride into the corresponding S-chloroacid chloride (XXVIII), which on treatment with methylaniline gave the anilide XXIX. Reduction of XXIX with lithium aluminum hydride gave the aldehyde XXX, which slowly reacted with... 

First we will consider phosphorus pentachloride (PC15). The traditional Lewis structure for PC15 (assuming d orbital participation)... 

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