Phosphorus compounds having coordination number

Phosphorus compounds having coordination number 1 2.1 Phosphinidenes (IUPAC phosphanylidenes) and terminal phosphinidene complexes9,10 

Caution This procedure must be performed in an efficient hood and gloves and goggles must be worn at all times. All operations must be carried out in the absence of oxygen and moisture. Prior to use, the reaction vessels must be heated with a heat-gun, evacuated twice to 10 3 mbar, and purged finally with argon (99.998%). All solvents must be carefully dried over alkali metals and distilled before use. 

Prepare a pressure-Schlenk tube (100 mL) equipped with a magnetic stirrer bar by heating the outer glass wall with the heat-gun, evacuate and purge with argon with the aid of the dual-bank vacuum and argon manifold. 

To the pressure-Schlenk tube (100 mL) add toluene (40 mL), (3,4-dimethyl-1-phenylphosphole)(pentacarbonyl)tungsten (6.15 g, 12 mmol) and a threefold excess of dimethyl acetylenedicarboxylate (5.12 g, 4.43 mL, 36 mmol). 

Prepare a pressure-Schlenk tube (100 mL) according to step 1. Charge the tube with the phosphanorbornadiene complex 5 (4.80 g, 6.24 mmol), toluene (40 mL) and a threefold excess of diphenylacetylene (2.02 g, 19 mmol). 

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Phosphorus compounds having coordination number 2 3.1 Alkylidenephosphines (k3-phosphaalkenes)33-35... 

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). 

In the course of the tempestuous development of organophosphorus chemistry, interest has only recently been focused on compounds of formally quinquevalent phosphorus having coordination number 3, such as 1, 2, or 3, although one of the other species of this kind has long been postulated as reactive intermediate of solvolysis of phosphorylation reactions. Definite evidence of even proof of the existence of such coordinatively unsaturated phosphorus compounds, however, has been obtained only recently in mechanistic studies, by trapping reactions with suitable cycloaddends, or actually by direct isolation. 

Phosphaalkynes of the type RC=P, featuring a three-valent phosphorus atom with coordination number 1 (A, a -P), represent novel organophosphorus compounds. Their chemistry has been extensively investigated since 1981, when the first synthesis of a kinetically stabihzed phosphaalkyne (t-BuC=P) was reported (283). Several reviews on the cycloaddition chemistry of these compounds with diazo compounds have been published (284—286). 

The large number of fluorine-containing compounds of sulfur results from the ability of sulfur to form strong covalent bonds with itself or with fluorine, oxygen, carbon, chlorine, phosphorus, and nitrogen. It is also important that sulfur may have coordination numbers of 2, 3, 4, 5, and 6. Formulas of a few compounds which illustrate the versatility of sulfur are ... 

The present survey is concerned exclusively with short-lived compounds of quinquevalent phosphorus with coordination number 3, which are not yet isolable in a classical sense with few exceptions they all possess at least one P/O double bond. Specifically, these are the metaphosphinates /, the metaphosphonates 2, and the metaphosphates 3. Studies of the methyleneoxophosphoranes 1 (X = O) and the monomeric metaphosphate ion 3 (Z = Oe, X = Y = O) have been especially thorough. 

In this chapter, synthesis, structure, and reactions of various classes of diazaphospholes have been reviewed. Recently used synthetic methods and variations for obtaining diversely substituted diazaphospholes have been discussed. On account of the cycloadditions on P=C bond of [1,4,2]- and [l,2,3]diazaphospholes, a number of organophos-phorus compounds incorporating a bridgehead phosphorus atom have become accessible. Recently reported complexation reactions of diazaphospholes, illustrate their capability to form transition metal complexes via different coordination modes. 

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