In chemistry, a precursor is a compound that contributes in a chemical reaction and produces another compound, or a chemical substance that gives rise to another more significant chemical product. Since several years metal-organic compounds are widely used as molecular precursors for the chemical vapor deposition process (MOCVD). The success of this method is mainly due to its adaptability and to the increasing interest for the low temperature deposition processes. Correlatively, the increasing demand of various thin film materials for new industrial applications is also a significant reason for the rapid development of MOCVD. Certainly, a wide variety of materials which could not be deposited by the conventional halide CVD process, because halide reactive do not exist or are not volatile, can now be grown by MOCVD. This includes metals and different multi-component materials such as semiconductor and intermetallic compounds as well as carbides, nitrides, oxides, borides, silicides and chalcogenides. Further significant advantages of MOCVD over physical processes are a capability for large scale production, an easier automation, a good conformal coverage, the selectivity and the ability to produce metastable materials.

Thus, effort has been directed at the synthesis of new molecular precursors. An overview is provided by several reviews covering fields of MOCVD such as, epitaxial growth of semiconductor compounds, and low temperature deposition of metals. An overview of metal-organic compounds used for the MOCVD growth of different kind of materials is reported in the following reviews. This is a list of precursor complexes synthesized thus far with suitable properties to be utilized for MOCVD processes.

List +Precursor, name, formulaCAS No.Chemical stabilityThemal stabilityEvaporation T (pressure)Vapour pressure (oC/Torr)Decomposition TOligommerizationCrystal structureMelting pointTG dataDSCIR spectraNMR dataSolubilityReferencesLi(TMHD), Lithium tetramethylheptanedionate, C11H19LiO222441-13-0Decomposes at low pressure and room temperatures, stable under N2 or Ar in sealed contanier and decomposes slowly in contact with moist air and rapidly in contact with water.Above 215 °C under high vacuum it decomposes to form ketenes and carbanions 268-270 °C (atmospehric pressure)NA265-268 °CSoluble in water D. Saulys, V. Joshkin, M. Khoudiakov, T.F. Kuech, A.B. Ellis, S.R. Oktyabrsky, L. McCaughan, Journal of Crystal Growth 217 (2000) 287-301Lithium bis(trimethylsilyl)amide, LiN(SiMe3)24039-Reacts violently with water.70-72 °CJ. Hamalainen, J. Holopainen, F. Munnik, T. Hatanpaa, M. Heikkila, M. Ritala, and M. Leskela, J Electrochem Soc, 159, A259 (2012).Lithium bis(ethyldimethylsilyl)amide, [Li(NSiMe2Et)2]2300585-49-3122/0.2Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Lithium tert-amyl(i-propyldimethylsilyl)amide137/0.2Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Lithium bis(3,3-dimethylbutyldimethylsilyl)amide225/0.9Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Lithium tert-amyl(i-butyldimethylsilyl)amide145/0.1Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Lithium tert-amyl(n-propyldimethylsilyl)amide171/0.3Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Lithium bis(n-propyldimethylsilyl)amide130/0.15Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Lithium bis(i-butyldimethylsilyl)amide145/0.05Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Lithium tert-amyl(triethylsilyl)amide157/0.095Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Lithium bis(n-butyldimethylsilyl)amide145/0.085Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Lithium dimethylamide, (CH3)2NLi3585-33-9Catches fire spontaneously if exposed to air and in contact with water releases flammable gas.https://pubchem.ncbi.nlm.nih.gov/compound/Lithium-dimethylamideDicyclohexylamidolithium, C12H24Li2N4111-55-1High sublimation temperature of 250 °C at which it is also partly thermally decomposing.250 °CPutkonen, M., Aaltonen, T., Alnes, M., Sajavaara, T., Nilsen, O., & Fjellvåg, H., Journal of Materials Chemistry, 2009, 19(46), 8767Li(acac), Lithium acetylacetonate, C5H7LiO218115-70-3HygroscopicAerosol 250 °CMethanol V. Bornand, Ph. Papet, E. Philippot, Thin Solid Films 1997, 304, 239.Lithium ethoxide, LiC2H5O2388-07-0Self heating and reacts violently with water.Decomposes at 325 °C. LiOEt is insoluble in hydrocarbons, soluble in EtOH (125g/L), α = 6, 4 (MS), ΔHform = -108.6Powder subliming at 100 °C/vacuo, 150 °C /10-2 torr.https://www.sigmaaldrich.com/catalog/product/aldrich/400203?lang=enLithium isopropoxide C3H7LiO2388-10-5"Sensitive to moisture and reacts with water. Material decomposes slowly in contact with moist air and rapidly in contact with water, possibly igniting. Avoid contact with moist air, water, acids, alcohols, ketones, esters, carbon dioxide, halogens."Highly flammable, stable under nitrogen or argon in sealed containershttps://pubchem.ncbi.nlm.nih.gov/compound/Lithium-isopropoxide#section=Chemical-and-Physical-Properties[Li(OtBu)]6, Lithium tert-butoxide, C4H9LiO1907-33-1Stable to light, heat, air, carbon dioxide and strong acids. Moisture sensitive, vigorous reaction to water.108-115 °C [1,2]283 °CSoluble in toluene, hexane, tetrahydrofuran and methyl tert-butyl ether." A. Dabirian, Y. Kuzminykh, S. C. Sandu, S. Harada, E. Wagner, P. Brodard, G. Benvenuti, S.Rushworth, P. Muralt, P. Hoffmann, Cryst. Growth Des. 2011, 1, 203. A. Tanaka, K. Miyashita, T. Tashiro, M. Kimura, T. Sukegawa, J. Cryst. Growth 1995, 148, 324. J. Hamalainen, J. Holopainen, F. Munnik, T. Hatanpaa, M. Heikkila, M. Ritala, and M. Leskela, J Electrochem Soc, 159, A259 (2012). Sigma-Aldtritch"LiTa(OEt)6127503-04-2The double alkoxides have sufficient stability using parent alcohol as solvent. Decomposes in contact with water.The thermal stability and volatility vary with respect to the reaction in solid or liquid state.230/0.2https://www.chemicalbook.com/ChemicalProductProperty_EN_CB2739827.htmlithium hexa-iso-propoxytantalate LiTa(i-OPr)6160-180/0.1https://www.tms.org/pubs/journals/JOM/9710/Xu/Xu-9710.htmlLiTa(t-OBut)6110-120/0.1https://www.tms.org/pubs/journals/JOM/9710/Xu/Xu-9710.htmlLithium niobium ethoxide, LiNb(OC2H5)6Moisture SensitiveSuyama, Y., Yamada, T., Hirano, Y., Takamura, K., & Takahashi, K. (2010). New Synthesis Process of Li, Na and K Niobates from Metal Alkoxides. Advances in Science and Technology, 63, 7–13. LiNb(i-OPr)6<140/0.2https://www.tms.org/pubs/journals/JOM/9710/Xu/Xu-9710.htmlLiNb(t-OBut)6110-120/0.1https://www.tms.org/pubs/journals/JOM/9710/Xu/Xu-9710.htmlSodium niobium ethoxide, NaNb(OC2H5)6Moisture SensitiveSuyama, Y., Yamada, T., Hirano, Y., Takamura, K., & Takahashi, K. (2010). New Synthesis Process of Li, Na and K Niobates from Metal Alkoxides. Advances in Science and Technology, 63, 7–13. Sodium cyclopentadienide, C5H5Na4984-82-1In contact with water releases flammable gases which may ignite spontaneously.Soluble in THF, benzene or liq. NH3"1. (a) Fischer, E. O.; Jira, R.; Hafner, K. Z. Naturforsch. 1953, 8b,(b) Fischer, E. O.; Hafner, W.; Stahl, H. O. Z. Anorg. Allg. Chem.1955, 282, 47. 2. Fehlhammer, W. P.; Herrmann, W. A.; O¨ fele, K. In Synthetic Methods of Organometallic and Inorganic Chemistry; Herrmann, W.A., Brauer, G., Eds.; Thieme: Stuttgart, 1997; Vol. 3, p 50. 3.https://spectrabase.com/spectrum/IMGzWBmNgJE. 4.https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-cyclopentadienide#section=GHS-Classification"Sodium hexafluoroacetylacetonate, NaC5HF6O222466-49-525/10.3230 °CSoluble in water and warm methoxypropanol.1. Zh. Neorg. Khim. 41, 411, (1996). 2. Rec. Trav. Chim. 114, 242, (1995)Sodium 2,2,6,6-tetramethylheptane-3,5-dionate, Na(thd)22466-43-9Sublimes between 170 and 255 °CM. Tiitta, M. Leskäla, E. Nykänen, P. Soinen, L. Niinstö, Thermochim. acta, 1995, 256 (1), 47-53Sodium 2,2,6,6-tetramethylheptane-3,5-dionate phenantroline, Na(thd)(phen)Sublimes around 210 °CD. Tsymbarenko, I. Korsakov, A. Mankevich, G. Girichev, E. Pelevina, A. Kaul, ECS Trans., 2009, vol.25, Iss.8, 633-638Sodium 2,2,6,6-tetramethylheptane-3,5-dionate 2,2'-bipiridyne, Na(thd)(bipy)It decomposes at 2 stages namely around 90 °C and 140 °CD. Tsymbarenko, I. Korsakov, A. Mankevich, G. Girichev, E. Pelevina, A. Kaul, ECS Trans., 2009, vol.25, Iss.8, 633-638Sodium-niobium hexakis(isopropoxide), NaNb(OiPr)6110-120/0.1Sodium bis(n-propyldimethylsilyl)amide213/0.3Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Sodium bis(i-butyldimethylsilyl)amide189/0.08Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Sodium bis(n-butyldimethylsilyl)amide231/0.5Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Sodium bis(n-hexyldimethylsill)amide265/0.3Broomhall-Dillard, R. N. R., Gordon, R. G., & Wagner, V. A., MRS Proceedings, 1999, 606Sodium Tert Butoxide, NaOC(CH3)3865-48-5Stable at room temperature. Decomposes at 300 °C; stable under N2 or Ar in sealed container and decomposes slowly in contact with moist air and violently in contact with water.At 300 °C sublimation: 254 °C (atmospheric pressure)Information not availableInformation not available263 °C "• 30 g/L at 20 °C Medium: tert-butyl alcohol • 70 g/L at 20 °C Medium: Toluene • 130 g/L at 20 °C Medium: Hexane • 380 g/L at 20 °C Medium: Tetrahydrofuran • 50 g/L at 20 °C Medium: xylene • 110 g/L at 20 °C Medium: octane • 220 g/L at 20 °C Medium: Diethyl ether • 450 g/L at 20 °C Medium: Dimethylformamide": https://www.nwmissouri.edu/naturalsciences/sds/s/Sodium%20tert-butoxide.pdf: https://www.albemarle.com/storage/components/T401225.PDF: Simone Manzini, Núria Huguet, Oliver Trapp, Rocco A. Paciello, Thomas Schaub; "Synthesis of acrylates from olefins and CO2 using sodium alkoxides as bases" Catalysis Today, Volume 281, Part 2, 2017, Pages 379–386, ISSN 0920-5861Potassium-niobium hexakis(ethoxide), KNb(OEt)6200/0.8Suyama, Y., Yamada, T., Hirano, Y., Takamura, K., & Takahashi, K. (2010). New Synthesis Process of Li, Na and K Niobates from Metal Alkoxides. Advances in Science and Technology, 63, 7–13. Potassium tert-butoxide (KOtBu) C4H9KO865-47-4Sublimes at temperature of 220 °C at pressure of 1 Torr NA220/1256 °C-258 °C Soluble in hexane, toluene, diethyl ether and tetrahydrofuran. Feuer et al.Journal of the American Chemical Society1956vol. 78p. 4364,4367 https://www.sigmaaldrich.com/catalog/product/aldrich/156671?lang=de&region=DE