Naked phosphorus

G. L. Simon and Lawrence F. Dahl First naked phosphorus complex... 

There are four comprehensive reference texts on phosphine coordination chem-istry. Two are somewhat out-of-date, but the article by Levason is more recent. However, all four give much useful information on synthetic procedures for the preparation of primary, secondary and tertiary phosphines diphosphines multidentate and macrocyclic phosphines mixed Group 15 donor and mixed Group 15/16 donor systems and phosphorus-containing heterocycles. The coordination chemistry of phosphorus has expanded to include P4 fragments, Pg rings, and even naked phosphorus atoms, for example, nine-coordinate P and -Pg systems. ... 

An interesting array of phosphorus ligands is realized by species where the phosphorus atoms are bonded only to metal or phosphorus atoms. They carry no substituents and are called naked phosphorus . Their chemical shift values cover a very... 

We will complete onr list of naked phosphorus units with P , P ", V - and Pj (see Fig. 7.41), all of which can be generated in the coordination sphere of transition metals, either by the elimination of subsituents on phosphorus, or by transfer of phosphorus units from one transition metal to the other. 

Fig. 7.41 Aromatic naked phosphorus Ugands and their complexes...

Transition metal phosphido clusters usually result from pyrolysis reactions in the presence of an external source of the phosphorus atom. PCI3, white phosphorus, PH3, and, more commonly, PPh3 have all been used in this respect, and it has been shown that the thermal decomposition of triphenylphosphine by successive loss of phenyl radicals can result in the formation of naked phosphorus atoms in interstitial cavities. This phosphorus metalation is thought to prevail in cluster chemistry because of the presence of several transition metal atoms neighboring the arylpho-sphine coordination site which aid the P-C bond cleavage process. 

There are liquids which cannot be prevented from bumping in this way, and the best plan is then to add a few small fragments of porous porcelain [a clay pipe broken in small pieces answers the purpose very well] or pumice-stone, or both, or a number of small tetrahedra of silver or platinum. A water or oil bath need only be used when a solid substance is present in the flask as, for instance, when a liquid is distilled over lime or phosphorus pentoxide, or when the liquid is liable to decompose when heated with the naked flame. 

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