Alkaline earth phosphides

In general, compounds having an active phosphoms—metal linkage react with alkyl haUdes. Such compounds include alkaU or alkaline-earth phosphides or phosphine derivatives, eg, Na P, PH2Na, XMgPR2, or... 

The alkah metal phosphides of formula M P and the alkaline-earth phosphides of formula M2P2 contain the P anion. Calcium diphosphide [81103-86-8] CaP2, contains P reaction with water Hberates diphosphine and maintains the P—P linkage. 

In addition to the heteronuclear clusters considered in the preceding paragraphs. As, Sb and Bi also form homonuclear clusters. We have already seen that alkaline earth phosphides M3P14 contain the [Pv] cluster isoelectronic and isostructural with P4S3, and the analogous clusters [Asy] " and [Sbv] have also been synthesized. Thus, when As was heated with metallic Ba at 800° C, black lustrous prisms of BasAs were obtained, isotypic with Ba3Pi4 these contained the [Asv] anion with dimensions as shown in Fig. 13.25(a).Again,... 

Calcium and other alkaline-earth phosphides incandesce in oxygen at about 300°C. Water... 

Alkaline Earth Phosphides.—An impure calcium phosphide, made by exposing lime at a red heat to the vapour of phosphorus, was used in the preparation of phosphine.2 Calcium phosphide probably is also formed during the manufacture of phosphorus by the electric furnace method g.v.). It has been prepared by heating calcium phosphate and lamp black in the electric arc furnace, and appeared as a crystalline reddish-black substance.3 Calcium phosphide prepared in this manner is only acted upon slowly by water at the ordinary temperature, but readily by aqueous solutions of strong acids. Concentrated nitric and sulphuric acids, and oxygen and chlorine, do not attack it at ordinary temperatures, but on heating it is oxidised, e.g. by chlorine above 100° C. and by oxygen above 300° C. 

Methods of Preparation—Alkali Phosphides—Alkaline Earth Phosphides— Copper, Silver and Gold Phosphides—Zino Group Phosphides—Boron and Aluminium Phosphides—Titanium Group Phosphides—Tin and Lead Phosphides—Arsenic, Antimony and Bismuth Phosphides—Chromium, Molybdenum and Tungsten Phosphides—Manganese Phosphides—Iron, Cobalt and Niokel Phosphides—Platinum Phosphides. 

In contrast to the phosphides mentioned above, there are a whole series of alkali and alkaline earth phosphides which contain a relatively large proportion of phosphorus, and which are insoluble and not easily attacked by water. Compounds of this kind contain highly polymerised chain, sheet or three-dimensional anions in which comparatively few P atoms form only two linkages. The 2-linked P atoms are associated with a formal negative charge although apparently not conferring the same ionic properties as possessed by the lower phosphorus content compounds just discussed. 

Reaction mechanism Based uprm a series of stoichiometric reactions, and in contrast to the previously discussed hydrophosphinatiOTi reactions (vide supra), it was postulated that unsaturated homoleptic heavier alkaline-earth phosphides are unlikely to be long-lived intermediates in the catalytic hydrophosphination of carbodiimides conducted in non-coordinating solvents. Rather, it was proposed that the phosphaguanidine product was acting as a ligand for the Lewis acidic metal center [114]. 

Phosphides are binary compounds containing anionic phosphorus (P ). Heavy metal, alkali, and alkaline earth metal phosphides exist but few of them are commercially important. Phosphides hydrolyze to the flammable and toxic gas phosphine (PH3). The hydrolysis reaction of aluminum phosphide is given below ... 

Low-temperature solvents are not readily available for many refractory compounds and semiconductors of interest. Molten salt electrolysis is utilized in many instances, as for the synthesis and deposition of elemental materials such as Al, Si, and also a wide variety of binary and ternary compounds such as borides, carbides, silicides, phosphides, arsenides, and sulfides, and the semiconductors SiC, GaAs, and GaP and InP [16], A few available reports regarding the metal chalcogenides examined in this chapter will be addressed in the respective sections. Let us note here that halide fluxes provide a good reaction medium for the crystal growth of refractory compounds. A wide spectrum of alkali and alkaline earth halides provides... 

Our experience has shown that the hydrolysis of aluminium phosphide with cold water is the most suitable method for the laboratory preparation of phosphine. Here it is important that the aluminium phosphide be as pure as possible in order to avoid the formation of spontaneously inflammable phosphine. The presence of small quantities of diphosphine and also higher phosphines are responsible for this spontaneous inflammability 96.276-278) jj. gp, pears, however, that these are only formed when P—P bonds are already present in the phosphide. Accordingly the hydrolysis of aluminium phosphide, prepared from the elements with phosphorus in slight excess, always leads to spontaneously inflammable phosphine. The formation of diphosphine and higher phosphines from aluminium or alkaline earth metal phosphides, which contain excess phosphorus, can be easily understood when the lattices of these compounds are considered. 

The chlorides, bromides, iodides, and cyanides are generally vigorously attacked by fluorine in the cold sulphides, nitrides, and phosphides are attacked in the cold or may be when warmed a little the oxides of the alkalies and alkaline earths are vigorously attacked with incandescence the other oxides usually require to be warmed. The sulphates usually require warming the nitrates generally resist attack even when warmed. The phosphates are more easily attacked than the sulphates. The carbonates of sodium, lithium, calcium, and lead are decomposed at ordinary temp, with incandescence, but potassium carbonate is not decomposed even at a dull red heat. Fluorine does not act on sodium bofate. Most of these reactions have been qualitatively studied by H. Moissan,15 and described in his monograph, Lefluor et ses composes (Paris, 1900). 

If we examine the distances listed in Table 7.2 some interesting facts emerge. For a given metal A. the A—P distance is constant as we might expect for an ionic alkaline earth metal-phosphide bond. Furthermore, these distances increase calcium < strontium < barium in increments of about 15 pm os do the ionic radii of Ca2+. St7, and Ba- (Table 4.4). However, the B—P distances vary somewhat more with no periodic trends (Mn. Cu larger Ni, Fe, Co smaller). Most interesting, however, is the huger variability in the P—P distance from about 380 pm (Mn. Fe) to 225 pm (Cu). As it Luros Out, the lower limit of 225 pm (Cu) is a typical value for a P— P bond (Table E.l,... 

Fig. 7.28 Unit ceO of an alkaline earth (A)/ transition meial (B)/ phosphide (P) of the ThCr2 i2-type structure. The distances listed in Table 7.2 are indicated. [Modified from Hoffmann, R. Zheng, C. J. Phys. Chem. 1985,89t 4175-4181. Reproduced with permission.]...

In 1816, P. L. Dulong 1 reported the isolation of the salt of Vacide au minimum d oxygene, which he proposed to name acide hypophosphoreux, hypophosphorous acid, H3PO2. It was obtained from the liquid produced when the phosphides of alkaline earths are treated with water. In the following year, H. Rose investigated a whole series of salts of this acid. 

P. L. Dulong showed that hypophosphorous acid or its salts are formed by the decomposition of phosphides of the alkaline earths by water and H. Rose, by boiling phosphorus with milk of lime, baryta-water, or an aq. or alcoholic soln. of potassium hydroxide. The following process has been recommended—vide infra, calcium hypophosphite ... 

The alkali and alkaline earth metals react with great energy when heated with the oxide, giving oxides and phosphides.3... 

Figure 20 Crystal structures of various ternary and quaternary phosphide oxides of the alkaline earth, rare earth, and actinoid metals. Alkaline earth (rare earth, actinoid), transition metal, phosphorus, and oxygen atoms are drawn as large light grey, medium grey, filled, and open circles, respectively. Some relevant coordination polyhedra around the oxygen atoms and the transition metal-phosphorus bonds are emphasized...

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