Phosphorus analogs

The first chapter covers organometallic complexes of boron, silicon, and phosphorus analogs of azoles. This chapter continues the series by A. P. Sadimenko (Fort Hare, South Africa) in which he is treating comprehensively organometallic complexes of heterocyclic compounds. So far, he has covered, in the volumes of AHC indicated, complexes of the following heterocycles ... 

Another method that has been used to prepare phosphaalkenes is the phos-pha-Peterson reaction, a phosphorus analog of the Peterson olefination [46-49]. In this reaction a lithium silylphosphide is treated with an aldehyde or ketone to yield the phosphaalkene (9). Analogous reactions can be conducted with bis(trimethylsilyl)phosphines (10) and ketones (11) using a catalytic quantity of anhydrous base (i.e., NaOH, KOH) [50]. Generally, the reactions proceed cleanly and in high yield. Sufficiently bulky substituents must be employed to stabilize the P=C bond and prevent rapid dimerization to 1,3-diphosphetaines. 

This review has shown that the analogy between P=C and C=C bonds can indeed be extended to polymer chemistry. Two of the most common uses for C=C bonds in polymer science have successfully been applied to P=C bonds. In particular, the addition polymerization of phosphaalkenes affords functional poly(methylenephosphine)s the first examples of macromolecules with alternating phosphorus and carbon atoms. The chemical functionality of the phosphine center may lead to applications in areas such as polymer-supported catalysis. In addition, the first n-conjugated phosphorus analogs of poly(p-phenylenevinylene) have been prepared. Comparison of the electronic properties of the polymers with molecular model compounds is consistent with some degree of n-conjugation in the polymer backbone. 

Arsen-1,1-dithiolates are less popular than their phosphorus analogs, perhaps due to fear of toxicity and foul smell of the ligands. 

In the framework of this concept a series of new mixed P/N ligands was prepared, employing the phosphorus-analogous Mannich reaction (Scheme 9). This transformation permits the substitution of primary or secondary amines by methylenephos-phine residues -CH2PRR (R, R = alkyl, aryl) through reaction with a secondary phosphine and formaldehyde (46). Based on the... 

V. Nitrogen and Phosphorus Analogs of Annulenes and Monocyclic Conjugated Ions... 

R. Engel, The use of carbon-phosphorus analog compounds in the regulation of biological processes, in Handbook of Organophosphorus Chemistry (Ed. R. Engel), Dekker, New York, 1992, pp. 559-600. 

A method for the production of the phosphorus analog of proline 145 has been described [137] ... 

An elegant synthesis of the phosphorus analog of tryptophan 150, which did not, it is true, exhibit biological activity, was reported in [150] ... 

Methylene trimethylarsorane is a monomer in benzene solution. Study of its H and 13C NMR spectra led to some unexpected conclusions, distinctly different from the findings with the phosphorus analog (80). As shown in Table III, the 5 and J characteristics of the CH2 nuclei are not nearly as different from those of the CH3 groups as are those of CH2 and CH3 in the phosphorus ylide (58). Whereas /(H2C) = 149 of the latter indicates an sp2 carbon (the value for ethylene is 150 Hz), J(H2C) = 131 in the former rather points to an sp3 carbon for the carbanion in (CH3)3-AsCH2. (Methane, 125 Hz CH3 in the ylide, 133 Hz )... 

A 35C1-NQR study (48) indicates that R3ASCI2 (R = Me or Ph), unlike the phosphorus analogs, possesses a trigonal-bipyramidal structure in... 

L Maier, P J Diel (1994) Synthesis, physical and biological properties of the phosphorus analogs of phenylalanine and related compounds, Phosphorus Sulfur 90( I —4 ) 259—279... 

The complexes of this stoichiometry containing ditertiary arsines probably outnumber those of tertiary phosphines. They have been prepared by the same general methods as the tertiary phosphine complexes, although unusually [RhCl2(diars)2]Cl has been prepared from Na3[RhCl6]. Despite the relative antiquity of this method,1044 it has not been generally adopted (equation 251). The physical properties of the ditertiary arsine complexes are listed in Table 82. It may be noted that the IR spectra of the sulfinato complexes indicate that these are S-bonded like their phosphorus analogs.230... 

---