Lithium phosphides

The phosphides are usually made by direct combination of the elements at elevated temperature. The reactive phosphoms is typically red phosphoms, white phosphoms, or phosphoms vapor. Lithium phosphide [12057-29-3] sodium phosphide [12058-85-4] Na P and potassium phosphide [12260-14-9] iron(III) phosphide [26508-33-8] EeP, and diiron phosphide [1310-43-6] Fe2P, are made in this manner. 

In 1989 we reported on the synthesis and structure of the first l,3-diphospha-2-sila-allylic anion 3a [4], mentioning its value as a precursor for phosphino-silaphosphenes. In analogy to 3a we obtained the anions 3b-f [5] by treatment of 4 equivalents of the lithium phosphide 1 with the adequately substituted RSiC, of which 3b and 3c were investigated by X-ray analyses. The very short P-Si bond lengths (2.11-2.13 A) of 3a-c and the almost planar arrangement of Pl-Sil-P2-Lil indicate the cr-character of the Lithium P-Si-P allyl complex. 

An unusual mixed lithium phosphide/lithium alkyl aggregate has been reported as arising from an attempted synthesis of Li PH(mes ) (46). Initial treatment of phosphorus trichloride with Li(mes ) is reported to give a mixture of the desired product, (mes )PCl2, and the side product (mes )Cl (via Li/Cl exchange) in an approximately 2 1 ratio. Reduction of this mixture with LiAlH4, followed by treatment with BuLi, then leads to rapid formation of Li PH(mes ), accompa-... 

Wright et al. have reported two cases where LiPHCy acts as a precursor to main group phosphinidine complexes. Reaction of the primary lithium phosphide with [AlMe N(mes) ]4 gives the heterometallic cage complex Li(THF) 4[ (AlMe)(ja-PCy) 2(ju.-PCy)]2 C6H5Me (95) (Fig. 12a). Reaction of [SnNBut]4 with 6 equiv of LiPHCy yields the complex cluster [ Sn2(PCy)3 2 Li(THF) 4], 2THF (96) (Fig. 12b). 

The reactions of lithium phosphides with chlorosilanes, which initially seemed so straightforward, turned out to be strikingly many-sided when PH-containing lithium phosphides are present. The formation of pure LiPH2 DME (DME = 1,2-dimethoxyethane) became feasible by coordination of a high boiling point ether (30). This method was employed by Klingebiel and collaborators (31) for the formation of... 

If for the reaction of Me2SiCl2 at 0°C a lithium phosphide is used, the latter formed by the introduction of excess PH3 in LiBu/hexane/Et20... 

It was not possible to obtain LisP by metallation of LiPHj with LiBu due to an ether cleavage reaction. Its formation succeeded through the reaction of PHj with an excess of LiBu in a solution of hexane/toluene and through the repeated action of LiBu on the lithium phosphide obtained initially (34). 

These two reactions, the substitution with elimination of LiCl and the PH lithiation by lithium phosphides, explain the formation of the compounds obtained in the reaction of Me2SiCl2 according to the reaction scheme of Scheme 7, in which all identified compounds are given a number. 

It is known from the preceding research that phosphorus-rich silylphosphanes or their related lithium phosphides undergo, with LiBu in ether, reactions in which a structural transformation occurs, as shown in Scheme 16 20). The reactions of the partially silylated tri- and cyclotetraphosphanes were explored in order to come closer to understanding the above reactions. It can be taken for granted that the P—C bond is not affected in such reactions. 

A. Reactions of Lithium Phosphides (MejSiljP—P(Li)—P(SiMe3) (CMej) AND [(MejCXMeaSilPliPLi in Ethers... 

Highly enantiomericaUy enriched lithium phosphides of type 204 were also prepared by oxidation of the lithium compounds 196 and oxidative degradation of the hydroxymethyl... 

---