Thiophosphoryl bond

Different OP compounds have structural similarities within classes. The phosphorus compounds have the characteristic phosphoryl bond, P=0. Most OP compounds have a phosphoryl bond or a thiophosphoryl bond (P=S). All OP compounds are esters of phosphorus with varying combinations of oxygen, carbon, sulfur, and nitrogen attached. These are classified as (1) phosphates (2) phos-phonates (3) phosphorothioates (4) phosphorodithioates (5) phosphorothiolates and (6) phosphoramidates. Further, the OP compounds are categorized as (1) aliphatic (2) phenyl and (3) heterocyclic derivatives. The aliphatic are carbon chainlike in structure. TEPP, which was used in agriculture for the first time in 1946, is a member of this group. Others include malathion, trichlorfon, monocrotophos, dimethoate, oxydemetonmethyl, dimethoate, dicrotophos, disulfoton, dichlorvos, mevinphos, methamidophos, and acephate. 

The thiophosphoryl bond is weaker and less polar than the phosphoryl linkage and the thiohalides are correspondingly less reactive and have lower dipole moments than their oxy analogues (POCI3, p = 2.39D PSCI3, p = 1.41D). The thiohalides are hydrolysed by water to form, eventually,... 

The primary ozonation products of organophosphorous pesticides in water such as diazinone, phenthione (MPP) and ediphenphos (EDDP) [39], are identifled by means of GC-MS analysis. The massspectra of the ozonation products of 17 organophosphorous pesticides point oxones as the primary reaction products. This fact is also confirmed by the SO generation resulting from the ozonation of their thiophosphoryl bonds. Oxones are relatively stable towards ozone attack but they are further hydrolyzed to trialkylphosphate and other hydrolysis products. However, with MPP the thiomethyl radicals are first oxidized to thiophosphoryl bonds giving MPP-sulfoxide, MPP-sulfone, MPP-sulfoxide-oxone are also obtained. Two main oxidation products have been identified at the oxidation of bis-dithio-type ethiones. Phosphate type EDDP is stable towards ozonolysis but its oxidation products are identified after hydrolysis [39]. 

There have apparently been no recent developments in reagents for desulphurizing sulphoxides that use pentavalent phosphorus compounds. Reagents that were reviewed in 1984 include phosphorus pentasulphide, thiophosphoryl bromide, Lawesson s reagent (1), and phosphorus pentachloride in the presence of a trap for CD ions. The traps used included an enamine or an N, JV-dialkylaniline. Presumably, the net effect of this reaction is to generate phosphorus trichloride in situ. The three thiophosphorus reagents obviously function because the P=S bond is some 150 kJ moD weaker than the P=0 bond . 

The reaction of 3 -amino-3 -desoxyadenosine 133 with thiophosphoryl chloride alTorded3, 5 -cyclothionophosphonate derivative 134 asamixture of P-diastereomcrs, which were separated by chromatography (Scheme 39) [70], The P-N bond cleavage,... 

While technically not "organometallics," enamines are reagents that can provide nucleophilic carbon for new bond formation. Two groups of researchers have reported on the use of such reagents for the formation of new carbon-phosphorus bonds through displacement of chloride from phosphorus.72 73 For example, displacement of bromide from phosphorus tribromide has been used for the introduction of a new thiophosphoryl functionality adjacent to an original carbonyl group (Equation 4.28).72 This approach provides a facile access to (3-ketophosphonates. 

The solid state structure of the thiophosphorylated host depicted in Fig. 3 shows unambiguously the all inward orientation of the four P=S bonds [71]. As in the oxidized parent compound 12c, a solvent molecule (acetonitrile) is entrapped in the cavity of the host, and another one is embedded at the lower rim between the four long alkyl chain substituents. 

Two isomers were expected according to the outside or inside orientation of the thiophosphoryl group. Only one isomer was characterized showing the P=S bond directed outside. The new hemicryptophane 22 presents a molecular cavity large enough to complex a toluene molecule as shown in the solid state structure depicted in Fig. 14. The toluene complex is stabilized through Van der Waals and specific r-interactions. 

The oxysulphide P4O6S4, formed by heating P4O6 with sulphur, forms a tetrahedral molecule similar to that of P4O10. The P—S bond length (1-85 A) is similar to that in the thiophosphoryl halides. 

Unlike the phosphorus chlorides mentioned above, thiophosphoryl chloride reacts with alkylmagnesium halides to form tetraalkyldiphosphane disulfides which contain a P-P bond 402-411... 

JO Sulfur and Selenium Containing Compounds. - The interaction of 0,0-dialkyl methylphosphonothioates acid with POCI3 to give the chloridates (286) and alkyl phosphorodichloridates parallels reactions of thiophosphoric esters already encountered. The use of Lawesson s reagent to replace the phosphoryl bond in (l,l-difluoroalkyl)phosphonic esters by thiophosphoryl, has been noted (see also reference 258). - ... 

Rotational barriers of the P-C bond in phosphoryl- and thiophosphoryl-stabilised carbanions have been studied by ab initio calculations on the 2-oxo-(and thioxo)-2-methyl-l,3,2-diazaphosphirane-(7) and -diazaphospholidine anions (8), at MP4(SDQ)/6 - 31+G //HF/6 - 31+G +ZPE levels. MNDO calculations have shown that 2-pyrrolinones cannot be phosphorylated with phosphorus nucleophiles. ... 

The only comprehensive and readily-available surveys of thio- and seleno-phosphonic and -phosphinic acids appear to be those in the compilation by Kosolapoff and Maier which appeared during the 1970s, and those in the Houben-Weyl volumes. Some further information relevant to heterocyclic systems which possess endo- or exo-cyclic phosphorus-sulphur bonds has been surveyed by Mann Gefter has also provided a useful compilation of syntheses and data for unsaturated thiophosphonates and related compounds. As in the preceding chapters concerned with the synthesis of the various classes of phosphonic and phosphinic acids, literature surveys have been presented for individual compounds and the field, as a whole, is surveyed annually". In addition. Hall and Inch reviewed the mechanistic implications of changes in stereochemistry following displacement reactions at phosphorus in cyclic phosphorus(V) esters and amides, and in so doing discussed the reaction s of many such thiophosphoryl compounds. 

In mixed anhydrides in which thiophosphoryl phosphorus is bonded to another heteroatom other than phosphorus, attack by a nucleophile may be diverted away from the phosphorus should the second reactive centre be more electrophilic. So, in the case of phos-phinothioic sulphonic anhydrides, although hydrolysis or acid-catalysed methanolysis of 101 (X = H) proceeds with inversion at phosphorus, attack by HO occurs at sulphur with retention of configuration of phosphorus whilst the hydrolysis of the much more reactive 101 (X = F) in aqueous dioxane proceeds with preponderant inversion of phosphorus... 

Herriott used the phosphorus epimers of 0-(-)-menthyl methylphenylphosphinoth-ioate to demonstrate the almost quantitative stereospecificity in the reaction with mCPBA by contrast, the use of trifluoroperoxyacetic acid was less successful, with a retention to inversion ratio of 21 79. A further feature in favour of mCPBA is the independence of its activity relative to solvent. Other extensive correlations were made by Inch and coworkers during investigations into the stereochemistry of displacement reactions at phosphorus in compounds based on a carbohydrate template 81 by means of structural assignments based on infrared absorption frequencies for the P=0 bond together with P NMR chemical shifts, they showed that mCPBA oxidation of thiophosphoryl or selenophosphoryl bonds (A or B = =S or =Se, B or A = Me or Ph) occurred highly stereoselectively with the formation of the phosphonate ester with retained stereochemistry ... 

Some chemical reactions which destroy the very nature of the phosphoryl bond P=Z (Z = O), also occur when Z = S or Se. The treatment of [(dichlorophosphino)methyl]phos-phonothioic dichloride (13 X = Cl) with SbF5 results in the initial replacement of all the chlorine by fluorine, followed by further fluorine transfer and the formation of the mono(tetrafluorophosphorane) (14) this step is then followed by the destruction of the thiophosphoryl group to give 15 on the other hand, SbF3 does not convert 16 (X = Cl) into 17, although 16 (X = F) is formed The phosphoryl group is not replaced by PF2 when acted upon by SbFj or AsF3". ... 

The mass spectra of a number of heterocyclic compounds have been reported. The fragmentation patterns of thiophosphoryl derivatives of phosphorinanes are sensitive to stereochemistry, thus for the series (95) facile loss of the HS radical is indicative of an axial PS bond. The seven-membered heterocycles (96 Ch = S, Se) undergo a remarkable migration of sulphur or selenium from phosphorus to carbon with ring cleavage. While exocyclic P-C bonds of five-and six-membered heterocycles in the phosphonic class may be readily cleaved with retention of the phosphorus ring system, the seven-membered ring (97) exhibits facile expulsion of a phosphorus radical. ... 

Thiophosphoryl halides, XjP S (X = Cl, Br), are weaker donors than Cl3P=0 and Ph3P=S. Only a few complexes are known [C13PS-AICI3], [Br3RS-AlBrj], [CljPS-SbCls] and [BrjPS-SbCIs]. The ligands are S-bonded, as v(P=S) decreases from 748 to ca. 650 cm and v(P-X) increases with adduct formation." ... 

---