Volatile imidazoles and group 2 imidazole based metal precursors
View Patent ↗Sterically hindered imidazole ligands are described, along with their synthesis, which are capable of coordinating to Group 2 metals, such as: calcium, magnesium, strontium, in an eta-5 coordination mode which permits the formation of monomeric or dimeric volatile complexes. A compound comprising one or more polysubstituted imidazolate anions coordinated to a metal selected from the group consisting of barium, strontium, magnesium, radium or calcium or mixtures thereof. Alternatively, one anion can be substituted with and a second non-imidazolate anion. Synthesis of the novel compounds and their use to form BST films is also contemplated.
1. A compound comprising a structure selected from the group consisting of:
wherein
R 1 , R 2 , R 3 and are each individually bulky groups selected from the group consisting of: C 1 -C 10 tertiary alkyl; C 1 -C 10 tertiary alkoxy; C 1 -C 10 tertiary alkylamine; C 1 -C 10 tertiary alkyl functionalized with a heteroatom substituted ring structure; C 1 -C 10 tertiary alkyl functionalized with an amide group; C 1 -C 10 tertiary alkyl functionalized with an ester group, and mixtures thereof;
(L) is a neutral ligand selected from the group consisting of aliphatic C 3 -C 20 ether or polyether, crown ether, amine, poly amine, amide, poly amide, ester, polyester, aromatic ether, aromatic ester, aromatic amide, aromatic amine, pyridine, imidazole, pyridine, pyrazine, furan, pyrrole, and mixtures thereof;
n=0-4; and
M=Ba, Sr, Ca, Ra, Mg, or mixtures thereof.
2. The compound of claim 1 wherein the imidazolates anions coordinate to M in a manner selected from the group consisting of: eta-1, eta-2, eta-3, eta-4 and eta-5 mode.
3. The compound of claim 1 selected from the group consisting of: Di-barium tetra(2,4,5-tris-t-butylimidazolate); Di-barium tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate); Di-barium tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate); and Di-barium tetra(2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate).
4. The compound of claim 1 selected from the group consisting of: Di-strontium tetra(2,4,5-tris-t-butylimidazolate); Di-strontium tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl) imidazolate); Di-strontium tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate); and, Di-strontium tetra(2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate).
5. The compound of claim 1 wherein R 1 , R 2 , and R 3 of each imidazolate anion are the same bulky group.
6. The compound of claim 1 wherein at least one of R 1 , R 2 , and R 3 of one imidazolate anion is joined to at least one of the R 1 , R 2 , and R 3 of another imidazolate anion to connect the two imidazolate anions.
7. The compound of claim 1 in a stainless steel container.