Phospha-alkyne

The translucent, cream-coloured benzene solvate was characterized by single-crystal X-ray analysis and by Pnrnr spectroscopy. The first free phospha-alkyne stable to polymerization... 

The direct vacuum pyrolysis of benzyldichlorophosphane also yields some phospha-alkyne in addition to a large amount of unidentified side products. In addition to the phenylphospha-acetylene which has a half-life of 7 minutes at 0°C, we could prepare the considerably more stable trimethylsilylderivative which has a half-life at room temperature of 50 minutes. The t-butyle derivative is entirely stable, as Becker reported recently-... 

The chemistry of trivalent phosphorus compounds in which phosphorus is one or two coordinate is rapidly developing. These systems contain sp or sp2 hybridized phosphorus and multiple TT-bonds between P and other elements and until 1964 it was believed that bond formation involving ptr-pir overlap was unfavourable. Subsequently certain -P=C systems resulted from the use of charged ( 1, 2, 3) and or delocalized systems (4J but it is only in the past few years that successful syntheses of phospha-alkenes, R2C=PR , and phospha-alkynes, RC=P, have been reported. These novel compounds are the subject of this paper. 

The P-C distances in simple phosphines, phospha-alkenes and phospha-alkynes are summarised in Figure 1 and the results contrasted with C-C, C=C and C=C bond lengths when a simple relationship is seen to exist. Additionally the data for the phosphabenzene systems shows excellent agreement with expectation. 

As shown in Scheme 33, cotrimerization of a sulfur atom and two phospha-alkyne molecules is possible. 

Interest in phospha-alkyne chemistry has also continued. Various trapping reactions of phospha-ethyne, MeCiP, have been described. The reaction of the phospha-alkyne (169) with a phosphinidene reagent has given the first 1-H diphosphirene (170), described as an extremely air sensitive, deep red liquid. 

Heating the phospha-alkyne Bu CsP in a sealed tube results in the formation of an air-stable cyclotetramer having the tetraphospha-cubane structure (171). A series of polycyclic cage polyphosphines has been formed in the reaction of the phospha-... 

Other aspects of the coordination chemistry of phospha-alkynes have... 

An interesting tetracyclic compound, for which full structural details are available, is obtained by treating a 1,3-aza-arsinine with a phospha-alkyne as shown in equation 3 . ... 

New, Unsaturated Three- and Four-Membered Rings Formal Addition of CH2, SiH2, GeH2, or SnH2 to Phospha-alkyne Triple Bonds. ... 

Phospha-alkyne systems have continued to attract interest. The phosphino-phospha-alkyne (324) arises as a transient intermediate in the thermolysis of a phosphino-phosphiranyl-diazo system.A convenient synthetic route to substituted phosphavinyl Grignard reagents (325) is provided by the regio- and stereo-selective addition of Grignard reagents to the phospha-alkyne... 

Bu C = P. Whereas the latter phospha-alkyne does not react with sulfur or selenium, the related system Pr 2NC = P yields the diphosphetene system (326). Also reported in this study is a slow cycloaddition of Bu C = P with carbon disulfide, eventually yielding a l-thia-2,4-diphosphole. Interest in the dimer-... 

A theoretical study of the intermediates involved in the formation of phospha-propyne from pyrolysis of vinylphosphirane has led to a new route to phospha-alkynes. Thus, pyrolysis of trimethylsilyl(l-phosphiranyl)diazomethane has yielded MeaSiC = P, via an intermediate 1-phosphiranylmethylene . Regioselec-tivity in the [3 + 2] cycloaddition reaction between phosphaethyne and diazomethane has been studied by theoretical techniques , and further examples of reactions of this type described . Cycloaddition of phospha-alkynes with silylenes has also been reported. The primary phosphine 324 has been isolated from the addition of diethylphosphite to t-butylphosphaethyne. The chemistry of phospha-alkyne cyclotetramer systems has been reviewed and the first examples of platinum(II) complexes of such cage systems described. Aspects of the reactivity of coordinated phospha-alkynes have received further study, and a remarkable metal-mediated double reduction of t-butylphosphaethyne to the complexed fluorophosphine 325 described Phosphorus-carbon-aluminium cage structures have been isolated from the reactions of kinetically stable phospha-alkynes with trialkylaluminium compounds and new phosphaborane systems have been obtained from the reactions of phospha-alkynes with polyhedral boranes . Further studies of wo-phospha-alkyne coordination chemistry have appeared . The reactivity of the ion 326 has been explored. ... 

Heteroatom-containing (cyclobutadiene)Co complexes (e.g. 237. 238 and 239) have been prepared by the reaction of heteroatom containing cobalt precursors with dipheny-lacetylene or by the reaction of cobalt precursors with phospha-alkynes. ... 

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