Phosphorus v Compounds

Phosphorus(v) Compounds. The n.m.r. spectrum of the five-co-ordinate compound Mc4POMe, which has an axial methyl group, is very complex, as a result of 

A full structure has been reported for the centrosymmetric hydrated 1,6-diphosphacyclodecane derivative (25), in which the ten-membered ring has the normal cyclodecane conformation. The phenyl groups are in trans-pseudo-axial positions and the structure is completed by hydrogen bonds between the hydrate water and phosphoryl groups from two molecules. 

Factors influencing the stereochemistry of phosphoranyl radicals have been investigated, pointing to trigonal-bipyramidal structures when electron-withdrawing substituents are present, but tetrahedral structures when the substituents are capable of inductive or conjugative stabilization of the charge on phosphorus.  

Crystal structures are now available for 2,2-diethoxyvinylidenetriphenyl-phosphorane, Ph3P—C=C(OEt)2,246 and the salt, [Ph3P=CH—PPh3]+Br .247 In the latter the P—C (bridge) distances are 1.710(4) and 1.695(4) A, and the PCP angle is 128.2°. Temperature-dependent H n.m.r. data for substituted aryl-bis(4,4 -dimethyl-2,2 -biphenylylene)phosphoranes are interpreted as showing that pseudorotation proceeds here by way of a square-pyramidal intermediate rather than by a simple Berry process.248 

A novel reaction leading to aryloxy- or arylthio-phosphonium salts involves treating a phosphine in the series Phn (Me2N)3, P, where n =0—3, with a phenol or thiophenol and carbon tetrachloride.249 The products, [Phn(Me2N)3 P(OAr)]+, can then be isolated as the hexachloroantimonates. 

Electron-diffraction data for the compounds Mc3MX (M = P or As X = O or S) are summarized in Table 3. Although the M—S bond distances are close to 

TaUe 3 Electron-diffraction data for some compounds MesMX 

Phosphorus(y) Compounds. The chemistry of phosphate species containing a peroxy linkage and the stereochemical implications of reaction mechanisms at phosphorus(v) have been reviewed. The cyclic 1,3,2-dioxaphospholans derived from meso- and ( )-hydrobenzoin show different n.m.r. spectra, and the crystal structures of the 2-phenoxy- and 2-/ -bromophenoxy-5-chloromethyl-5-methyI-2-oxo-l,3,2-dioxaphosphorinans have been determined. Factors influencing the stereochemistry in substituted 1,3,2-dioxa-phosphorinans as shown mainly by n.m.r. data are considered in a number of papers. Changes in the O—H stretching frequency of phenol in the 

Sengupta, J. K. Chakladar, and A. K. Chatteijee, /. Inorg. Nuclear Chem., 

Schwartz and M. Van der Veen, Inorg. Nuclear Chem. Letters, 1973, 9, 39. 

Peroxomonophosphoric acid (PMPA) oxidizes anthranilic acid and p-aminobenzoic acid in aqueous acid to the azoxy compounds, via nucleophilic attack of the unprotonated nitrogen group on the peroxo oxygen. The same authors also report on the oxidation of 3-aminopyridine by PMPA.  

The formation and chemical properties of monomeric metaphosphates have been discussed. These are of considerable interest in a biochemical context, and generally as reaction intermediates in the hydrolysis of phosphates. The ready conversion of metaphosphate to orthophosphate probably does not reflect the essential instability of the three-coordinate phosphorus(V) species, but the greater relative stability of orthophosphate. 

Kinetic studies have been carried out on the hydrolysis of phenyl phosphatosulfate as models for the enzymatic hydrolysis of compounds with P-O-S linkages. These compounds are involved as intermediates in biological sulfur metabolism. The hydrolysis of phenyl phosphatosulfate is catalyzed by Mg , which activates the P-O-S link towards nucleophilic 

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Short-Lived Phosphorus(V) Compounds Having Coordination Number 3... 

Regitz, M., and Maas, G. Short-Lived Phosphorus (V) Compounds Having Coordination Number 3, 97,71-119(1981). 

A series of neutral hexacoordinate phosphorus(v) compounds have been synthesized making use of an acidic phosphorus atom and a coordinating ligand. Compound 39 represents a bicyclic bridgehead phosphorus compound produced <1996IC325>. 

The solids considered in this section are phosphorus oxynitrides and nitridooxophosphates. They are pentavalent phosphorus(V) compounds and correspond to a partial substitution of nitrogen, under the nitride form N3, for oxygen 02 within P04 tetrahedra, resulting in the formation of mixed P(0, N)4 tetrahedra. 

Other synthetic routes to phosphazenes, using phosphorus(v) compounds as substrates, are more limited. An example of the reaction of a nitrile with a phos-phorus(v) chloride is provided by Scheme 4.48 In benzene solution, or in the absence... 

Figure 17.15. Phosphorus (Is) fluorescence spectra from chemical and mineral standards. The dashed line represents the edge position (2152 eV) of inorganic phosphorus (V) compounds (redrawn after Brandes et al., 2007).

This very common coordination number usually leads to a tetrahedral configuration for phosphoric acid, phosphates, and many phosphorus(V) compounds. In these compounds, the P(V) atom forms one double bond and three single bonds with other atoms. Figure 15.4.2(e) shows the structure of P4O10, whose symmetry is Td. The length of the terminal P=0 bond is 143 pm, and the bridging P-O bond is 160 pm. The bond angle O-P-O is 102°, and P-O-P is 123°. 

Neutral phosphorus(V) compound containing divalent tridentate azo ligands were studied by Cavell and coworkers.83 The 31P and, 9F chemical shifts and /(31P, 19F) coupling constants are collected in Tables 9 and 10 for (2,2 -azophenoxy)trifluorophosphorus (22), /rans-(2,2 -azophenoxy)(trifluoro-methyl)difluorophosphorus (23) and cis-(2,2 -azophenoxy)(trifluoromethyl) difluorophosphorus (24). 

Although many reactions of organomagnesium compounds with phosphorus(v) compounds have been reported [A, 12], few of them have... 

Confusion has been caused by the inconsistent use of the abbreviations HMPT/HMPA for (Me2N),P/(Me2N),PO. The use of Normant s trivial name, hexametapol for the phosphorus (v) compound avoids ambiguity... 

The Michaelis-Arbuzov reaction is the most used and well-known method for the synthesis of phosphonates and their derivatives and may also be used to synthesize phosphinates and tertiary phosphine oxides. The simplest form of the Michaelis-Arbuzov reaction is the reaction of a trialkyl phosphite, 3, with an alkyl halide, 4, to yield a dialkyl alkylphosphonate, 6, and new alkyl halide, 7 (Scheme 2). During this transformation the phosphorus atom of a ter-valent phosphorus(III) species (3) acts as a nucleophile resulting in the formation of an intermediate alkoxy phosphonium salt 5, containing a new [P—C] bond. The precise structure of the intermediates 5 is a subject of debate—as reflected by common reference to them as pseudophosphonium salts —with a penta-coordinate species (containing a [P—X] bond) being proposed and detected in some cases.18 Decomposition (usually rapid under the reaction conditions) of the intermediate 5 by nucleophilic attack of X- on one of the alkyl groups R1, with concomitant formation of a [1 =0] bond yields the product pentavalent phosphorus(V) compound (6) and the new alkyl halide, 7. 

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