METHOD OF PREPARING IODOSILANES AND COMPOSITIONS THEREFROM

1 . A method for preparing an iodosilane having the formula (I) or (II)

SiR x I y   (I), or

I y R x Si—SiR x I y   (II),

wherein x is 1, or 2, y is an integer of from 1 to 3, and wherein the sum of x plus y is 4 in formula (I) and 3 in formula (II) at each Si center, and wherein R is hydrogen or a C 1 -C 6 alkyl group;

which comprises contacting a halosilane having the formula

SiR x D y or D y R x Si—SiR x D y ,

wherein D is chloro or bromo,

with an iodide reactant comprising aluminum.

2 . The method of claim 1 , wherein y is 2.

3 . The method of claim 1 , wherein the iodide reactant comprising aluminum is a compound having the formula (A):

[M +q ] z [Al(X) 3 I w ] q   (A),

wherein z is 0 or 1, w is 0 or 1, M is chosen from (i) Group 1 metal cations chosen from Li + , Na + , K + , Rb + , and Cs + , (ii) Group 2 metal cations chosen from Mg 2+ , Ca 2+ , Sr 2+ , and Ba 2+ ; and (iii) ammonium, C 1 -C 6 alkyl, or benzyl ammonium cations; q is the valence of M and is 1 or 2, and X is chloro, bromo, or iodo, provided that when z and w are zero, X is iodo.

4 . The method of claim 3 , wherein z is 1 and w is 1.

5 . The method of claim 4 , wherein M is Li + or Na + .

6 . The method of claim 4 , wherein M is chosen from NH 4 + , (CH 3 ) 4 N + , (CH 3 CH 2 ) 4 N + , (CH 3 CH 2 CH 2 ) 4 N + , and (CH 3 CH 2 CH 2 CH 2 ) 4 N + .

7 . The method of claim 3 wherein M is Mg +2 or Ca +2 .

8 . The method of claim 1 , wherein the iodide reactant comprising aluminum is aluminum triiodide.

9 . The method of claim 8 , wherein the aluminum triiodide is generated in situ from aluminum metal and iodine.

10 . The method of claim 3 , wherein the compound of formula (A) is chosen from LiAl(I) 4 , NaAl(I) 4 , KAl(I) 4 , Mg[Al(I) 4 ] 2 , Ca[Al(I) 4 ] 2 , LiAl(Cl) 3 I, LiAlCl(I) 3 , NaAl(Cl) 3 I, NaAlCl(I) 3 , KAl(Cl) 3 I, KAlCl(I) 3 , Mg[Al(Cl) 3 I] 2 , Mg[Al(Cl)(I) 3 ] 2 , Ca[Al(Cl) 3 I] 2 , Ca[Al(Cl)(I) 3 ] 2 , NH 4 Al(I) 4 , NH 4 Al(Cl) 3 I, NH 4 Al(Cl)(I) 3 , NaAl 2 I 7 , NaAl 3 I 10 , and Al(I) 3 .

11 . The method of claim 1 , wherein the iodide reactant comprising aluminum is a compound of the formula

MAl m I n ,

wherein M is an alkali metal, and m is 2 and n is 7, or m is 3 and n is 10.

12 . The method of claim 11 , wherein the iodide reactant is a compound of the formula NaAl 2 I 7 .

13 . The method of claim 11 , wherein the iodide reactant is a compound of the formula NaAl 3 I 10 .

14 . The method of claim 3 , wherein the iodide reactant comprising aluminum is generated in situ from

a. AlX 3 and M +q X q ;

b. Al o , X 2 , and M +q X q ;

c. AlX 3 , M o , and X 2 ; or

d. Al o , M o , and X 2 , wherein q represents the valence of M.

15 . The method of claim 1 , wherein the compound of formula (I) is chosen from

SiHI 3 ,

SiH 2 I 2 ,

SiH 3 I,

SiH 2 CH 3 I,

SiH 2 (CH 2 CH 3 )I,

SiH 2 (CH 2 CH 2 CH 3 )I,

SiH 2 ((CH 3 ) 2 CH)I,

SiH 2 (CH 2 CH 2 CH 2 CH 3 )I,

SiH 2 ((CH 3 ) 3 C)I,

SiHCH 3 I 2 ,

SiH(CH 2 CH 3 )I 2 ,

SiH(CH 2 CH 2 CH 3 )I 2 ,

SiH((CH 3 ) 2 CH)I 2 ,

SiH(CH 2 CH 2 CH 2 CH 3 )I 2 ,

SiH((CH 3 ) 3 C)I 2 ,

SiCH 3 I 3 ,

Si(CH 2 CH 3 )I 3 ,

Si(CH 2 CH 2 CH 3 )I 3 ,

Si((CH 3 ) 2 CH)I 3 ,

Si(CH 2 CH 2 CH 2 CH 3 )I 3 ,

Si((CH 3 ) 3 C)I 3 ,

I 3 Si—SiI 3 .

I 2 CH 3 Si—SiCH 3 I 2 ,

I 2 (CH 3 CH 2 )Si—Si(CH 2 CH 3 )I 2 ,

I 2 (CH 3 CH 2 CH 2 )Si—Si(CH 2 CH 2 CH 3 )I 2 ,

I 2 ((CH 3 ) 2 CH)Si—Si((CH 3 ) 2 CH)I 2 ,

I 2 (CH 3 CH 2 CH 2 CH 2 )Si—Si(CH 2 CH 2 CH 2 CH 3 )I 2 ,

I 2 ((CH 3 ) 3 C)Si—Si((CH 3 ) 3 C)I 2 ,

ICH 3 HSi—SiHCH 3 I,

I(CH 2 CH 3 )HSi—SiH(CH 2 CH 3 )I,

I(CH 2 CH 2 CH 3 )HSi—SiH(CH 2 CH 2 CH 3 )I,

I((CH 3 ) 2 CH)HSi—SiH((CH 3 ) 2 CH)I,

I(CH 2 CH 2 CH 2 CH 3 )HSi—SiH(CH 2 CH 2 CH 2 CH 3 )I, and

I((CH 3 ) 3 C)HSi—SiH((CH 3 ) 3 C)I.

16 . The method of claim 1 , wherein the compound of formula (I) is H 2 SiI 2 .

17 . The method of claim 16 , wherein the iodide reactant comprising aluminum is Al(I) 3 .

18 . The compound of claim 1 , wherein the compound of formula (I) is HSiI 3 .

19 . A precursor composition comprising a compound of the formula SiH 2 I 2 , having less than 1 ppm of antimony, silver, or copper impurities and less than about 1 ppm of sodium or lithium impurities.

20 . A precursor composition comprising a compound of the formula SiH 2 I 2 , having less than about 10 ppb (parts per billion) of aluminum impurities.