Phosphorus mixed halides

With one mole of phosphorus pentachloride, MeNHa.BFa gives a series of mixed halides (13) of which only one (/i = 1) was isolated. In each halide the fluorine atoms were shown to be bonded to boron by the appearance of iiB-isp and absence of spin-spin coupling. An analogous A-phenyl... 

Cryoscopic and ebullioscopic measurements indicate that the halides of phosphorus, arsenic, antimony, titanium and tin readily undergo reciprocal interaction with interchange of halogen atoms and that mixed halides can be formed11 (see p. 103). Melting and freezing point curves are, however, generally of the eutectic or mixed crystal types, without... 

The nitrogen halides have the general formula NX3, but not NX5 as in the case of phosphorus. However, some mixed halides such as NF2C1 are known. Fluorine also forms N2F4 and N2F2 (these compounds will be discussed later) that are analogous to hydrazine and diimine, respectively. Except for NF3 (b.p. -129 °C), the compounds are explosive. Because of this behavior, most of what is presented here will deal with the fluorine compounds. 

Several mixed halide compounds are known that have formulas such as PCI3F2, PF3C12, and PF3Br2. These compounds are prepared by adding a halogen to phosphorus trihalides that contain a different halogen, and a typical reaction is... 

With mixed phosphorus(V) halides, similar reactions occur [900,903] ... 

It was McCormack who, in 1953, in the patent literature, first reported the cycloaddition of phosphorus(III) halides to l,3-dienes . As then represented, the sequence took the form depicted in reaction 13 (X = Cl or Br). The careful addition of water to the crystalline 1 1 adduct, formulated as a halogenophosphonium salt (92), gave the unsaturated phosphinic chloride (93, R = Br or Cl) or acid (93, R = OH). Since the original publication of the procedure, the application of modern spectroscopic techniques has demonstrated that the final products in such reactions are mixtures of the 3-phospholene (93) and 2-phospholene (94) isomers, conveniently represented, when admixed and in unknown proportions, as 95. It has since become apparent that the relative proportions of the isomeric forms 93 and 94 of any derivative depend on the nature of the halogen X and on the manner of work-up thus, in an acidic work-up medium, the products tend to have the structure 94, but neutralization during the hydrolysis step leads to derivatives of the isomeric 93. The reaction consists simply in mixing the reactants at room temperature and... 

Known compounds with a 6-coordinated phosphorus atom (6.542) are still relatively few in number. Apart from the long-established PFg and PClg and some mixed halide anions (Chapter 4.6), only within the last few decades have compounds been prepared with several kinds of atom directly linked to P in six-coordination. 

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