Highly reactive metal hydrides, process for their preparation and use

Abstract

The invention relates to powdery, highly reactive alkali and alkaline earth hydride compounds, and to mixtures with elements of the third main group of the periodic table of elements (PTE) and to the preparation thereof by reacting alkali or alkaline earth metals in the presence of finely dispersed metals or compounds of the third main group of the PTE, wherein the latter have one or more hydride ligands or said hydride ligands are converted in situ, under the prevailing reaction conditions, i.e., in the presence of hydrogen gas or another H source, into hydride species, and to the use thereof for the preparation of complex hydrides and organometallic compounds.

1 . Highly reactive mixtures of alkali metal or alkaline earth metal hydrides MH n *, where n=1 or 2 corresponding to the valence of the metal M, and highly reactive metal M 2 * selected from the group consisting of B, Al, Ga, In, and optionally with another metal hydride M 1 H m * with M 1  selected from an alkali metal, an alkaline earth metal or an element from the group of the rare earths, wherein the molar ratio between MH n *, M 2 * and M 1 H m * is 1:0.001 to q/6:0 to p/6, preferably 1:0.01 to q/6:0 to p/6. 
     
     
         2 . The mixtures according to  claim 1 , characterized in that M and M 1  are selected from Li, Na or Mg, and M 2 =Al. 
     
     
         3 . A method for preparing highly reactive alkali metal or alkaline earth metal hydrides MH n * where n=1 or 2 corresponding to the valence of the metal M, characterized in that metals M of the first or second periods of the periodic table of elements are reacted with a compound of general formula M 1   x [M 2 H 3+x ] b  under inert conditions or under hydrogen atmosphere according to
     M+o/ 6 M   1   x   [M   2   H   3+x ] b   −−>MH   n   *+p/ 6 M   1   H   m   *+q/ 6  M   2 * ,   wherein   M 1 =an alkali metal selected from the group consisting of Li, Na, K, Rb, Cs, an alkaline earth metal selected from the group consisting of Be, Mg, Ca, Sr, Ba;   x=0 or 1,   M 2 =an element of the 3rd main group of the periodic table of elements selected from the group consisting of B, Al, Ga, In;   b=the valence of M 1 ;   m=1 or 2, corresponding to the valence of the metal M 1 ;   n=1 or 2, corresponding to the valence of the metal M;   and in the case in which x=0, p=0, and   for M=alkali element, o and q=2;   for M=alkaline earth element, o and q=4 and in the case in which x=1:   for M and M 1 =alkali metals, o, p, q=2;   for M and M 1 =alkaline earth metals, o, p=2, and q=4;   for M=alkali metal and M 1 =alkaline earth metal, o, p=1, and q=2, and   for M =alkaline earth metal and M 1 =alkali metal, o, p, q=4.   
     
     
         4 . A method for preparing highly reactive alkali metal or alkaline metal hydrides MH n * where n=1or 2 corresponding to the valence of the metal M, characterized in that metals M of the first or second period of the periodic of table of elements are reacted with a compound of general formula M 1   x [M 2 (A 1   y A 2   z ) 3+x ] b  or in the presence of finely dispersed, highly reactive metal M 2+  with a mean particle size D 50  in the range from 0.01 to 100 μm in the presence of hydrogen gas or another source of hydrogen according to 
       
         
           
           
               
               
           
         
         wherein 
         M 1 =an alkali metal selected from the group consisting of Li, Na, K, Rb, Cs, an alkaline earth metal selected from the group consisting of Be, Mg, Ca, Sr, Ba, or an element from the group of the rare earths selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; 
         x=0 or 1; 
         n=1 or 2, corresponding to the valence of the metal M; 
         b=the valence of M 1 ; 
         M 2 =an element of the 3rd main group of the periodic table of elements, selected from the group consisting of B, Al, Ga, In;
 A 1 =H or an alkyl group, branched or unbranched, containing 1-18 C atoms, wherein the up to four A groups can be identical or different; 
 A 2 =an alkoxy residue OR where R=alkyl with 1-8 C atoms, a dialkylamino residue —NR 2  where R=alkyl with 1-8 C atoms or a halogen from Cl, Br, I; 
 y can assume the value 1, 2 or 3, and wherein y+z=3. 
 
       
     
     
         5 . The method for producing highly reactive metal hydrides MH n * according to  claim 3  or  4 , characterized in that the reaction is carried out in an aprotic solvent or solvent mixture, wherein at least one of the solvent components is an open-chain or cyclic ether, a tertiary amine or a hydrocarbon, either in pure form or as any mixtures of at least two of the listed solvents. 
     
     
         6 . The method according to  claim 5 , characterized in that an open-chain or cyclic ether selected from the group consisting of diethyl ether, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, tetrahydropyrane, dioxane, dioxolane; a tertiary amine selected from the group consisting of triethylamine, tributylamine, morpholine, or a hydrocarbon selected from the group consisting of saturated C 4 -C 18  hydrocarbons, preferably pentanes, hexanes, heptanes, octanes; aromatic compounds selected from the group consisting of benzene, toluene, ethylbenzene, xylenes, cumene. 
     
     
         7 . The method according to  claims 3  to  6 , characterized in that the reaction temperature is in the range between −20 and 150° C., preferably 0 and 100° C., and particularly preferably between 25 and 70° C. 
     
     
         8 . The method according to  claim 4 , characterized in that one operates under H 2  atmosphere, wherein the H 2  pressure is between 1 and 300 bar, particularly preferably 10-100 bar. 
     
     
         9 . The method according to  claim 4 , characterized in that the compound M 1   x [M 2 (A 1   y A 2   z ) 3+x ] b  is used in catalytic quantities from 0.001 to 20 mol %, preferably from 0.01 to 10 mol %, with respect to the metal M. 
     
     
         10 . The use of the metal hydrides MH n * according to  claim 1  or  2  or obtained according to one of  claims 3  to  8  for the reaction with Lewis acids of the 3rd main group of the periodic table of elements or for the hydrometalation of olefins. 
     
     
         11 . The use according to  claim 10  for the preparation of metal hydridoborates M[HBR 3 ] n  or metal hydridoaluminates M[HAI(OR) 3 ] n  with R=unbranched, cyclic or branched alkyl groups containing 1 to 12 C atoms. 
     
     
         12 . The use according to  claim 10 , characterized in that a Lewis acid is selected from the group consisting of tri-sec-butylborane, trisiamylborane, tricyclohexylborane, aluminum trimethylate, aluminum-tri(tert-butylate), aluminum tri(tert-pentylate). 
     
     
         13 . The use according to  claim 10  for the hydrometalation of an olefin R 1 R 3 C═CR 2 R 4  where R 1 , R 2  and R 3 =H, wherein preferably an a-olefin from the group consisting of 1-propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene is selected. 
     
     
         14 . The use according to  claim 10  for the hydrometalation of an olefin R 1 R 3 C═CR 2 R 4  where R 2  and R 4 =alkyl groups containing 1-12 C.