Method for preparing metal complexes of polydentate beta-ketoiminates

1. A method for preparing a group 2 metal-containing polydentate β-ketoiminate represented by the following structure A:

wherein M is a metal selected from the group consisting of Mg, Ca, Sr, and Ba; R 1 , R 3 , R 5 , and R 6 are independently selected from an alkyl group, a fluoroalkyl group, a cycloaliphatic group, and an aryl group; R 2 is selected from a hydrogen atom, an alkyl group, an alkoxy group, a cycloaliphatic group, and an aryl group; and R 4 is an alkyenyl bridge, wherein the method comprises:

reacting M in a reaction mixture comprising a tridentate ketoimine ligand and an alcohol selected from the group consisting of methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, iso-butanol, n-pentanol, neo-pentanol, and combinations thereof, for a reaction time of from about 4 to about 48 hours to obtain the group 2 metal-containing polydentate β-ketoiminate at a yield greater than 80%, wherein the tridentate ketoimine ligand comprises a compound represented by the following structure B:

wherein R 1 , R 3 , R 5 , and R 6 are independently selected from an alkyl group, a fluoroalkyl group, a cycloaliphatic group, and an aryl group; R 2 is selected from a hydrogen atom, an alkyl group, an alkoxy group, a cycloaliphatic group, and an aryl group; and R 4 is an alkyenyl bridge.

2. The method of claim 1 wherein M comprises strontium.

3. The method of claim 1 wherein the molar ratio of M to the alcohol in the reaction mixture ranges from about 0.1 to 5.

4. The method of claim 1 wherein the reaction mixture further comprises an organic solvent.

5. The method of claim 4 wherein the organic solvent comprises toluene and hexane.

6. The method of claim 4 wherein the organic solvent comprises tetrahydrofuran.

7. The method of claim 4 wherein the reacting step is carried out in the presence of the organic solvent wherein at least one of the tridentate ketoimine ligand and the alcohol is at least partially soluble therein.

8. The method of claim 4 wherein the metal and the tridentate ketoimine ligand are added in the organic solvent and then the alcohol is added.

9. The method of claim 8 wherein the alcohol is added to the reaction mixture portion wise to avoid sudden exothermal reaction.

10. The method of claim 4 wherein the reaction mixture is refluxed at the boiling point of the organic solvent.

11. The method of claim 1 wherein the metal-containing polydentate β-ketoiminate comprises bis(2,2-dimethyl-5-(dimethylaminoethyl-imino)-3-hexanonato-N,O,N′)strontium.

12. The method of claim 1 wherein the metal-containing polydentate β-ketoiminate comprises bis(2,2-dimethyl-5-(1-dimethylamino-2-propylimino)-3-hexanonato-N,O,N′)strontium.

13. The method of claim 1 wherein the metal-containing polydentate β-ketoiminate comprises bis(2,2-dimethyl-5-(1-ethylmethylaminoethyl-imino)-3-hexanonato-N,O,N′)strontium.

14. The method of claim 1 wherein the metal-containing polydentate β-ketoiminate comprises bis(2,2-dimethyl-5-(1-methyethylamino-2-propylimino)-3-hexanonato-N,O,N′)strontium.

15. The method of claim 1 wherein the metal-containing polydentate β-ketoiminate comprises bis(2,2-dimethyl-5-(1-diethylaminoethyl-imino)-3-hexanonato-N,O,N′)strontium.

16. The method of claim 1 wherein the metal-containing polydentate β-ketoiminate comprises bis(2,2-dimethyl-5-(1-diethylamino-2-propylimino)-3-hexanonato-N,O,N′)strontium.

17. The method of claim 1 wherein the alcohol is iso-propanol.