Phosphoryl Halide Complexes

The complex ions Na(POCl3)4 and Al(POCl3)6 are formed in the system POCl3/NaAlCl4/H20. These are believed to have tetrahedrally and octahedrally coordinated metal atoms as in (4.324) [49,50]. 

A major use for phosphoryl chloride is in the synthesis of phosphoryl esters (Chapter 6). It will also react with Grignard reagents to give phosphine oxides (6.112), and with secondary amines to give amino-substituted phosphine oxides or phosphonic dichlorides (7.96). 

Phosphoryl chloride is reduced by carbon to the trichloride (4.206), and with liquid ammonia, phosphoryl triamide is obtained (7.48). 

Pyrophosphoryl chloride, P2O3CI4, is a colourless oily liquid mp = -16.5°C, bp = 215°C (d). It can be made by passing chlorine into a suspension of phosphorus pentoxide in phosphorus trichloride and carbon tetrachloride, when PCI5 is formed, which then reacts as in (4.326). Studies with radioactive labelled P atoms indicate that the P-O-P linkages in the P4O10 molecule are utilised in the new molecule which has a structure analogous to that of (4.325). 

Pyrophosphoryl chloride is hydrolysed by water and it reacts readily with ammonia to give the tetramide (H2N)2P(0)0P(0)(NH2)2 and other products (Chapter 7). Polymeric (POjCOn can be prepared by the oxidation of PCI, with NjO. The mixed halide FC1P(0)0P(0)C1F can be obtained from POCljFandPAo. 

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With phosphoryl halides, complexes of the type X3P-O-MX3 (M = Al, Ga, In) are formed, and phosphonium salts containing the AICI4 ion exist in the pentahalide addition compounds (Chapter 4.6). 

The formation of pentacoordinated stannates 62a and 62b has been detected in the hydrolysis of the organotin halide complexes with phosphoryl ligands containing aliphatic amino group in the ligand. The tentative reaction scheme is shown in equation ll282. 

Reaction of 3-substituted indoles with halogens can be more complex initial 3-halogenation occurs generating a 3-halo-3//-indole, ° but the actual products obtained then depend upon the reaction conditions, solvent etc. Thus, nucleophiles can add at C-2 in the intermediate 3-halo-3//-indoles when, after loss of hydrogen halide, a 2-substituted indole is obtained as final product, for example in aqueous solvents, water addition produces oxindoles (20.13.1) comparable methanol addition gives 2-methoxyindoles. 2-Bromination of 3-substituted indoles can be carried ont nsing A -bromosuccinimide in the absence of radical initiators. 2-Bromo- and 2-iodo-indoles can be prepared very efficiently via a-lithiation (20.5.1). 2-Halo-indoles are also available from the reaction of oxindoles with phosphoryl halides. Some 2,3-diiodo-indoles can be obtained by iodination of the indol-2-ylcarboxyfic acid. ... 

A shift, up to 100 cm, of v(P=0) to lower values occurs when the phosphoryl oxygen is involved in additional bonding. This is observed in H-bonded dimers such as (5.345a) and in metal halide complexes such as (4.323) ... 

The complexation of anionic species by tetra-bridged phosphorylated cavitands concerns mainly the work of Puddephatt et al. who described the selective complexation of halides by the tetra-copper and tetra-silver complexes of 2 (see Scheme 17). The complexes are size selective hosts for halide anions and it was demonstrated that in the copper complex, iodide is preferred over chloride. Iodide is large enough to bridge the four copper atoms but chloride is too small and can coordinate only to three of them to form the [2-Cu4(yU-Cl)4(yU3-Cl)] complex so that in a mixed iodide-chloride complex, iodide is preferentially encapsulated inside the cavity. In the [2-Ag4(//-Cl)4(yU4-Cl)] silver complex, the larger size of the Ag(I) atom allowed the inner chloride atom to bind with the four silver atoms. The X-ray crystal structure of the complexes revealed that one Y halide ion is encapsulated in the center of the cavity and bound to 3 copper atoms in [2-Cu4(//-Cl)4(//3-Cl)] (Y=C1) [45] or to 4 copper atoms in [2-Cu4(/U-Cl)4(/U4-I)] (Y=I) and to 4 silver atoms in [2-Ag4(/i-Cl)4(/i4-Cl)] [47]. NMR studies in solution of the inclusion process showed that multiple coordination types take place in the supramolecular complexes. 

As a part of our program to develop new adjuvants for the into-cell delivery of phosphorylated nucleotide-type antiviral agents (see Section 3 of this chapter), we became interested in developing a sapphyrin-based approach to phosphate anion chelation. As proved true for halide anion recognition, important initial support for the idea that sapphyrins could function as phosphate anion receptors came from single crystal X-ray diffraction studies. In fact, to date, five X-ray structures of sapphyrin-phosphate complexes have been obtained. ... 

Protonated forms of the large-ring macrocycle [24]Ng02 (5) and related compounds have been shown to be active as synthetic phosphorylation catalysts in ATP synthesis. It is likely that in this case the substrate enters the macrocyclic cavity to some extent, or is enveloped by it. Evidence for this possibility comes from the crystal structure of the chloride salt of 5-6H (Figure 1) in which a chloride ion is enveloped within a cleft formed by the boat-shaped conformation of the macrocy-cle. The crystal structure of the nitrate salt of 5-4H has also recently been determined and the host again adopts a boat-like conformation as it interacts with the anion. The hydrochloride salt of the smaller [22]Ng binds two chloride anions above and below the host plane in a similar way to 1. Molecular dynamics simulations indicate that the pocket-like conformation for 5-6H is maintained in solution, although Cl NMR experiments demonstrate that halide ions are in rapid exchange between the complexed and solvated state. 

The C-phosphorylation of alkylindoles was realized using the magnesium and lithium derivatives of indole. The ( -substituted compound 3e was obtained from 2-lithio-l-methylindole (le), and the C(3)-substituted compounds 4a,b were obtained by means of the indole Grignard reagent Id [11, 16, 17]. It was shown [17] that 3-indolylphosphonite 4b forms complexes with copper(I) halides. 

By far the most frequently used method is the deprotonation with potassium tert-butoxide, which gives the potassium salts in nearly quantitative yields. The method seems to be usable for any bis(chalcogenophosphinyl and -phosphoryl)imide and has been employed for a broad diversity of derivatives, regardless of the nature of the chalcogen.2,26,30,33,36-38,49,89,91,99 If the salts are needed for further use in reactions with metal halides to form complexes, the potassium salt can be used in situ, without isolation, e.g., with zinc(II) chloride or palladium and platinum chloro complexes.41,43 Potassium metal in THF also forms the salt K[SPh2PNPPh2S] in 82% yield, 38 but the method is not practical for preparative purposes. Potassium-crown ether complexes, [K(18-crown-6)][Q1Ph2PNPPh2Q1] with Q1 = O,92 Q1 = S,93 and Q1 = Se,98 have been prepared by direct complexation of the potassium salt with the macrocyclic ligand. 

A-Phosphorylated imidazoles and benzimidazoles can be made by direct phosphorylation by halides, esters, amides, amidoesters, isocyanates, and thiocyanates of phosphorus-containing acids, or from reaction of phosphonic or phosphinic imidazolides with a sulfonic acid or anhydride <82CB1636>. Stable charge transfer complexes are produced when a 1 1 or 1 2 ratio of imidazole (or benzimidazole) and sulfur trioxide are refluxed in ether, dioxane, THE, or 1,2-dichloroethane. These complexes are stable on storage in the absence of water and have sharp melting points. Indeed, the benzimidazole SO3 complex must be boiled for five hours in water to decompose it. On fusion, the complexes form the C-sulfonic acids (see Section 3.02.5.3.3) <87CHE1084>. Sulfonyl chlorides readily A-sulfonate imidazoles <94JMC332>. 

A study of the reaction of phenylethynyl halides with methoxide anion revealed a complex addition-elimination mechanism for this substitution. Such reactions require application of DMSO as a solvent and afford alkynyl ethers only in 42-46% yield. Reactions of phosphorylated chloroacetylenes 74 with alkoxide anions are even less selective and afford products of nucleophilic addition to the triple bond as major products. However, analogous reaction of 74 with phenoxide anion gives phenoxyacetylenes 75 in moderate yield (equation 46). ... 

An IR study of the complexes fonned from TiCl4 and dialkyl H-phosphonates indicates that at low temperatures, a a-donor complex through the phosphoryl oxygen atom is formed [415], Similar to the analogous complexes of tin halides, these titanium complexes are thermally unstable and easily undergo dealkylation with cleavage of alkyl halides even at low temperatures. 

Other PT processes reported recently include the phosphorylation of amines " or alcohols, and the conversion of aromatic amines to azides by diazo transfer (Equation 8) to the amine anion. An interesting recent development is the use of PTC in organometallic chemistry, notably the conversion of aryl halides to carboxylic acids mediated by a Pd complex (Equation 9). 

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