Magnesiums boron hydrides

Ethyl-2-methyl-3-(10,11) -dihydro-5H-dibenzo [a,d] cycloheptene-5-ylidene)-1 -pyrrolinium iodide (4.7 g) was dissolved in 7 cc of methanol. To this solution there were added 1.4 g of sodium boron hydride within about 80 minutes with stirring and stirring of the solution was continued for two hours to complete the reaction. The reaction mixture was acidified with 10% aqueous hydrochloric acid solution and then the methanol was distilled off. The residual solution was alkalized with 20% aqueous sodium hydroxide solution and extracted with ether. The ether layer was dried over magnesium sulfate and the ether was distilled off. The resulting residue was further distilled under reduced pressure to yield 2.0 g of 1-ethyl-2-methyl-3-(10,11 ) dihydro-5H-dibenzo[a,d]cycloheptene-5-ylidene)pyrrolidine (boiling point 167°C/4 mm Hg.). 

There are many compounds that contain boron and hydrogen, and they are known collectively as the boron hydrides. Six boron hydrides were prepared by Alfred Stock in 1910-1930 by the addition of hydrochloric acid to magnesium boride that was produced in small amounts when B203 was reduced with magnesium. 

The earliest syntheses of boron hydrides were grossly inefficient, giving mixtures of products of A-5% total yields. These procedures were based upon the reaction of magnesium boride with hydrochloric acid. Only much later were yields of 11% obtained when 8N phosphoric acid was used (2). 

Dlborane(6) was obtained from the thermal decomposition of B4H10 (2). In view of the restricted amounts of products obtained by the use of magnesium boride in boron hydride syntheses, development of their chemistry proceeded slowly even after techniques had been acquired for handling these materials. 

Complex aluminum and boron hydrides can contain other cations. The following compounds are prepared by metathetical reactions of lithium aluminum hydride or sodium borohydride with the appropriate salts of other metals sodium aluminum hydride [55], magnesium aluminum hydride [59], lithium borohydride [90], potassium borohydride [9i], calcium borohydride [92] and tetrabutylammonium borohydride [95]. 

Magnesium hydride forms double hydrides with aluminum hydride and boron hydride ... 

Borides Carbon boride, CB6. and silicon borides SiB3 and SiB6 are hard, crystalline solids, produced in ihe electric furnace magnesium boride, Mgi B2, brown solid, by reaction of boron oxide and magnesium powder ignited, forms boron hydrides with HC1 calcium boride, Ca3 B2, forms boron hydrides and hydrogen gas with IIC1. 

When magnesium is heated with boron, the product is magnesium boride, MgB2 (sometimes written as Mg3B2). The hydrolysis of the compound produces Mg(OH)2 and a boron hydride. Instead of the expected product of BH3, borane, the product is B2H6, diborane. 

Trialkylaluminum and alkylaluminum hydrides associate with alkyl or hydride bridges. Since there are no available lone-pair electrons with which to form bridges by standard two-center two-electron interactions, multicenter bonding is invoked in the same manner as for electron-deficient boranes (see Boron Hydrides), alkyllithium (see Alkali Metals Organometallic Chemistry), dialkylberyllium and dialkylmagnesium compounds (see Beryllium Magnesium Organometallic Chemistry). 

A,0-acetal OMe H or acidic reagent, magnesium halide, aluminum or boron hydride... 

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