Halogen free syntheses of aminosilanes by catalytic dehydrogenative coupling
Compounds and method of preparation of Si—X and Ge—X compounds (X=N, P, As and Sb) via dehydrogenative coupling between the corresponding unsubstituted silanes and amines (including ammonia) or phosphines catalyzed by metallic catalysts is described. This new approach is based on the catalytic dehydrogenative coupling of a Si—H and a X—H moiety to form a Si—X containing compound and hydrogen gas (X=N, P, As and Sb). The process can be catalyzed by transition metal heterogenous catalysts such as Ru(0) on carbon, Pd(0) on MgO) as well as transition metal organometallic complexes that act as homogeneous catalysts. The —Si—X products produced by dehydrogenative coupling are inherently halogen free. Said compounds can be useful for the deposition of thin films by chemical vapor deposition or atomic layer deposition of Si-containing films.
1. A compound of formula:
where n=1 to 5; R 1 , R 2 and R 3 are independently selected from the group consisting of H, linear or branched C 1 to C 6 alkyl, linear or branched C 1 to C 8 alkenyl, linear or branched C 1 to C 8 alkynyl, C 6 to C 10 aryl, linear or branched C 1 to C 6 alkyl ether, silyl, trimethyl silyl, or linear or branched C 1 to C 6 alkyl-substituted silyl.
2. A method of preparing a compound according to claim 1 , comprising the steps of:
a) contacting the reactants R 1 HN(CR 3 )═NR 2 (amidine) and SiH 3 Si n H 2n+1 , in the presence of a transition metal catalyst forming a reaction mixture; where the molar ratio of SiH 3 Si n H 2n+1 to R 1 HN(CR 3 )═NR 2 is at least 1:1;
b) optionally adding a solvent to the reaction mixture;
c) maintaining the reaction mixture at a temperature between about 0° C. to about 300° C.;
d) allowing the reaction to proceed to form [(R 1 N(CR 3 )═NR 2 )(SiH 2 Si n H 2n+1 )]; and
e) separating the product [(R 1 N(CR 3 )═NR 2 )(SiH 2 Si n H 2n+1 )] from the reaction mixture,
wherein the reaction temperature may vary during the synthesis and is maintained such that the temperature of the reaction mixture is not allowed to drop below about 0° C. and not exceed about 300° C.
3. A compound of formula:
where n=0 to 4; R 1 , R 2 , R 3 , R 4 , R 5 , R 6 are independently selected from the group consisting of H, linear or branched C 1 to C 6 alkyl, linear or branched C 1 to C 8 alkenyl, linear or branched C 1 to C 8 alkynyl, C 6 to C 10 aryl, linear or branched C 1 to C 6 alkyl ether, silyl, trimethyl silyl, or linear or branched C 1 to C 6 alkyl-substituted silyl.
4. A method of preparing a compound according to claim 3 , comprising the steps of:
a) contacting the reactants R 1 HN(CR 3 )═NR 2 (amidine) and SiH 3 Si n H 2n SiH 3 , in the presence of a transition metal catalyst forming a reaction mixture where the molar ratio of R 1 HN(CR 3 )═NR 2 to SiH 3 Si n H 2n SiH 3 is about 1:1 to about 5:1;
b) optionally adding a solvent to the reaction mixture;
c) maintaining the reaction mixture at a temperature between about 0° C. to about 300° C.;
d) allowing the reaction to proceed to form [(R 1 N(CR 3 )═NR 2 )(SiH 2 Si n H 2n SiH 3 )];
e) adding R 4 HN(CR 6 )═NR 5 to the reaction mixture;
f) maintaining the reaction mixture at a temperature between about 0° C. to about 300° C.;
g) allowing the reaction to proceed to form [(R 1 N(CR 3 )═NR 2 )(R 4 N(CR 6 )═NR 5 )(SiH 2 Si n H 2n SiH 2 )]; and
h) separating the product [(R 1 N(CR 3 )═NR 2 )(R 4 N(CR 6 )═NR 5 )(SiH 2 Si n H 2n SiH 2 )] from the reaction mixture,
wherein the reaction temperature may vary during the synthesis and is maintained such that the temperature of the reaction mixture is not allowed to drop below about 0° C. and not exceed about 300° C.