Tungsten phosphides

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. 

Tungsten Phosphides.—The combination of tungsten and phos-jjhorus was lirst studied by Pelletier vvho, however, did not publish any exact data. The later investigations of Wright and Defacqz appear to have established the existence of four definite phosphides. 

Of the many published procedures for the synthesis of WCLt, the two most commonly employed methods are reduction of WCle with red phosphoras in a sealed tube, or reduction of WClg with W(CO>6 in refluxing chlorobenzene. The suitability of WCLj for some chemical uses is dependent on its preparative route because of associated impurities. For example, tungsten phosphides and phosphorus are potential contaminants in WCI4 that is derived from reduction with red phosphorus. Tungsten hexacarbonyl, W(CO)e, is an expensive reductant, toxic CO is liberated, and chlorobenzene can be difficult to remove. 

Trimercuiy tetraphosphide, 4616 Tungsten carbide, 0563 Uranium carbide, 0562 Uranium dicarbide, 1028 Zinc phosphide, 4876 Zirconium dicarbide, 1029 METAL PNICTIDES... 

In addition to the tungsten(II) bonde mentioned above, the element forms at least two other borides, W2B and WB2 it forms a similar series of phosphides, W2P, WP, and WP2 as well as W02 (brown oxide), W4On (blue oxide), and WO3 (yellow oxide), and two sulfides, WS2 and WS3. The tungsleu(IV) oxide and sulfide are representative uf the simple Lelravalent compounds, which also include a tetrabromide, WBr4, and tetraiodide, WI4. Like lire drhalides, these tetiahalides undergo hydrolysis quite readily. 

Tetraamminelithium dihydrogenphosphide, 4590 Thorium dicarbide, 1023 Titanium carbide, 0558 Trimercury tetraphosphide, 4611 Tungsten carbide, 0560 Uranium carbide, 0559 Uranium dicarbide, 1024 Zinc phosphide, 4870 Zirconium dicarbide, 1025 METAL ACETYLIDES N-METAL DERIVATIVES METAL HYDRIDES METAL OXIDES METAL SULFIDES NITRIDES... 

Phosphenium complexes, with tungsten carbonyls, 5, 624 Phosphides... 

In the manufacture of tungsten lamps the tungstic oxide may be reduced by heating with yellow or red phosphorus in an atmosphere of hydrogen. The tungsten powder containing phosphide which results is suitable for drawing into the filaments. 

The strong chemical reactivity of phosphorus allows the formation of single and mixed phosphides with several metals (7-10). Phosphides that are relevant to hydrotreating catalyst formulations (Table II) involve bonding of phosphorus with molybdenum (or tungsten), cobalt, and/or nickel. 

Tungsten Subphosphide, W4P3.—By strongly heating a mixture of phosphoric acid and tungstic anhydride in a carbon crucible, lustrous steel-coloured crystals of this phosphide are obtained. The crystals are si.x-sided prisms of density 5-21. It conducts electricity well, is very" stable in air even at higher temperatures, and is very resistant to acids. When heated in a current of oxygen it bums brilliantly. It dissolves in a fused mixture of alkali carbonate and nitrate. 

Ylides Coordinated to Metals.- The "phospha-Wittig" reaction has been reported for the first time. The phosphonate-stabilised phosphide (65) (prepared by base treatment of the tungsten complex (64)) reacts with carbonyl compounds to give phosphaallene complexes (66). 

H2. Hydrogen, molybdenum complex, 27 3 tungsten complexes, 27 6, 7 H2UP, Lithium dihydrogen phosphide, (LiH,P), 27 228... 

Chromium. Molybdenum. Tungsten. Cocondensation of PH3 with chromium vapor at 60 K leads to the formation of a PH3 complex of Cr [78]. Chromium powder with PH3 forms phosphides of different composition at 700 to 950 C. The reaction at 850 C yields CrP, whereas at 950 C only the lowest phosphide, CrgP, is obtained the latter dissociates at 10OO C to give Cr [79]. Gaseous PH3 is inert in the presence of metallic Mo on an AI2O3 support at about 350 C [80]. The reaction of PH3 with W at 850 C gives WP [81]. 

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