Volatile organic barium, strontium and calcium compounds and method for the preparation of layered materials with barium, strontium or calcium oxides or fluorides from these compounds

Abstract: Volatile organic barium, strontium and calcium compounds, which consist of the complex of a barium-, strontium- or calcium-β-diketonate and one or more coordinating ligands, characterized in that at least one coordinating ligand of the barium or strontium compound is formed by a neutral oxygen or a neutral nitrogen donor ligand, or one of the coordinating ligands of the calcium compound is formed by a neutral oxygen donor ligand, and method for the preparation of layered materials which contain one or more of the barium, strontium or calcium oxides or fluorides, by means of a deposition technique, characterized in that with the deposition technique, especially MO-CVD, one starts with the present new volatile organic barium, strontium or calcium compounds either corresponding with the respective metal oxides, or corresponding with the respective metal fluorides.

Description: The invention relates to new volatile organic barium, strontium and calcium compounds. Volatile organic barium, strontium and calcium compounds are known. P.H. Dickinson, A. Sanjurjo, T.H. Geballe, D. Hildenbrandt, G. Graig, M. Zisk, J. Collman, S.A. Banning and R.E. Sievers for instance, in J.Appl.Phys.1989, 66, 444, describe the use of the 2,2,6,6-tetramethyl-3,5-heptanedione (thd) compound of - among others - Ba, that is {Ba(thd) 2 }, as precursor for so-called chemical vapor deposition (CVD) processes. This compound has been found to dissociate partially during evaporation, because of which its concentration in the vapor phase diminishes as a function of time, at a constant temperature of the source, in this case Ba(thd) 2 in the solid phase. Other volatile barium-, strontium- and calcium-β-diketonates are also known, for instance from the work of J.E. Schwarzberg, R.E. Sievers and R.W. Moshier, in Anal.Chem. 1970 , 42, 1828. It has been found, however, that when these compounds are heated to 200°C and higher temperatures, which is necessary to bring them from the solid phase into the gas phase, a rapid decomposition occurs. Barium-, strontium- and calcium-β-diketonates are described - among others - by D.E. Fenton in "Comprehensive Coordination Chemistry", Editor in Chief G. Wilkinson, in Volume 3, Chapter 23.4.1., pages 25 and on. EP-A-0178786 discloses adducts of Mg and Zn β-diketonates with the bidentate ether 1,2-dimethoxyethane and their use as source materials for chemical vapour deposition reactions. It has now been found that the problems encountered with known volatile compounds so far can be overcome by applying certain combinations of barium-, strontium- and calcium-β-diketonates and coordinating ligands. According to a first aspect of the present invention there is provided volatile, thermally stable alkaline earth metal β-diketonate donor ligand complex of the formula where M is Ba, Ca or Sr; R' and R'', which may be the same or different, are alkyl or substituted alkyl, aryl or substituted aryl groups, the said substituted alkyl and aryl groups containing as the said substituent(s) one or more fluorine atoms, and with the further proviso that at least one of the groups R' and R'' is such a substituted group: L is a neutral oxygen donor ligand selected from triglyme, tetraglyme, hexaglyme, 18-crown-6 and tetraethyleneglycol monomethyl ether; and m has a value of from 1 - 6. Preferably R' and R'' is -CF 3 or n-C 3 F 7 . Preferably the β-diketonate is any one of: hexafluoroacetylacetone 1,1,1,-trifluoroacetylacetone 1,1,1,2,2,3,3-heptafluoro-8,8-dimethylocta-4,6-dione. Preferably the stable alkaline earth metal β-diketonate donor ligand complex is any one of the following: 1. Ba{CF 3 C(O)CHC(O)CF 3 } 2 {CH 3 O(CH 2 CH 2 O) 3 CH 3 } 2. Ba{CF 3 C(O)CHC(O)CF 3 } 2 {CH 3 O(CH 2 CH 2 O) 4 CH 3 } 3. Ba{CF 3 C(O)CHC(O)CF 3 } 2 {(CH 2 CH 2 O) 6 } 4. Ba{CF 3 C(O)CHC(O)CF 3 } 2 {CH 3 O(CH 2 CH 2 O) 6 CH 3 } 5. Ba{CF 3 C(O)CHC(O)CF 3 } 2 {HO(CH 2 CH 2 O) 4 CH 3 } 6. Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 {CH 3 O(CH 2 CH 2 O) 4 CH 3 } 7. Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 {CH 3 O(CH 2 CH 2 O) 6 CH 3 } 8. Sr{CF 3 C(O)CHC(O)CF 3 } 2 {CH 3 O(CH 2 CH 2 O) 4 CH 3 } 9. Ca{CF 3 C(O)CHC(O)CF 3 } 2 {CH 3 O(CH 2 CH 2 O) 3 CH 3 } According to a second aspect of the present invention there is provided a method for the preparation of layered barium, calcium or strontium deposits, wherein there is used a volatile, thermally stable complex of barium, calcium or strontium of the first aspect of the present invention. Preferably, the said deposit is formed by a metal-organic vapour deposition (MO-CVD) process employing the said complex as a volatile source of barium, calcium or strontium. Preferably, one starts with the preformed complex and transports that preformed complex into the vapour phase. Preferably, one starts with the metal β-diketonate and entrains that β-diketonate into the vapour phase by contact with the coordinating ligand L in the vapour phase. According to a third aspect of the present invention there is provided a volatile, thermally stable alkaline earth metal β-diketonate donor ligand complex of the formula where M is Ba, Ca or Sr; R' and R'', which may be the same or different, are alkyl or substituted alkyl, aryl or substituted aryl groups, the said substituted alkyl and aryl groups containing as the said substituent(s) one or more fluorine atoms: L is a neutral oxygen donor ligand selected from triglyme, tetraglyme, hexaglyme, 18-crown-6 and tetraethyleneglycol monomethyl ether; and m has a value of from 1-6. DETAILED DESCRIPTION OF THE INVENTION The invention therefore relates to new volatile organic barium, strontium and calcium compounds, which consist of the complex of a barium-, strontium- or calcium-β-diketonate and one or more coordinating ligands, characterized in that at least one coordinating ligand of the barium or strontium compound is formed by a neutral oxygen or a neutral nitrogen donor ligand or one of the coordinating ligands of the calcium compound is formed by a neutral oxygen donor ligand. The general structure formula of a compound according to the invention is given on the formula sheet. In this structure formula, M represents a barium, strontium or calcium ion with valence 2, R' and R'' represent the side chains of the diketonate, L represents the neutral oxygen or neutral nitrogen donor coordinating ligand and m the number of coordinating ligands, and wherein R 1 and R'' are as defined above. Complexes of barium-, strontium- and calcium-β-diketonates according to the invention possess a much higher volatility and thermal stability than similar barium-, strontium- and calcium-β-diketonates lacking the complexing ligand. As mentioned above, the β-diketonates of barium, strontium and calcium, when lacking a complexing ligand, are thermally instable. With barium-, strontium- or calcium-β-diketonate ligand complexes according to the invention, conditions can be attained under which, for instance in a CVD process, during a longer period of time (several days), a constant mass transport of calcium, strontium or barium compounds per unit of time can be maintained. Appropriate neutral oxygen donor ligands in practical examples of compounds according to the invention are: acyclic ethers with the general formula ROR', with R and R' representing a C 1 -C 8 group; cyclic ethers, (CRR') n O, {(CRR') n O} m , with R,R' = H, (substituted) alkyl, n,m = 1-6, for instance crown ethers like 18-crown-6 and other; glycol ethers, R'O-(CHRCH 2 O) n -H, e.g. tetraethyleneglycol monomethyl ether and R'O-(CHRCH 2 O) n -R'', in which R = H,Me and R' ,R'' = (substituted) alkyl, n = 1-6, for instance R = H, R' = R'' = Me, glyme (n = 1; dimethoxyethane,DME), diglyme (n = 2), triglyme (n = 3), tetraglyme (n = 4), hexaglyme (n - 6) and other; polyethers, RO[(CR'R'') n O] m H and RO[(CR'R'') n O] m R' in which R = (substituted)alkyl and R',R'' = H, (substituted)alkyl, n = 1-4, m = 1-6; alcohols, ROH, HO(CR′R″) n OH, HO{(CR′R″) n O} m H, with R = (substituted) alkyl and R′,R″ = H, (substituted)alkyl, n,m = 1-6; ketones, R-C(O)-R′, R-C(O)(CR″R‴) n C(O)-R′, with R and R′ representing a C 1 -C 8 group and R″,R‴ = H, (substituted)alkyl, n ≥ 2 ; aldehydes, RC(O)H, with R = C 1 -C 8 group; anhydrides, {RC(O)} 2 O, with R = C 1 -C 8 group; amides, RR′NC(O)H, with R and R′ representing a C 1 -C 8 group, for instance dimethylformamide (DMF) and other; sulfoxides, RS(O)R′, with R and R′ representing a C 1 -C 8 group, for instance dimethylsulfoxide (DMSO) and other; sulfones, RS(O) 2 R′, with R and R′ representing a C 1 -C 8 group ; cyclic sulfones, (CRR′) n S(O) 2 , with R,R′ = H, (substituted)alkyl, for instance {(CH 2 ) 4 SO 2 } (sulfolane) and other. Appropriate neutral nitrogen donor ligands are: nitriles, RCN, with R = C 1 -C 8 group; dinitriles, NC(CRR′) n CN, with R and R′ = H and/or C 1 -C 8 group(s), n≧ 1; amines, RR′R″N, with R, R′, R″ = H and/or C 1 -C 8 group(s); di- and polyamines, for instance tetramethylethylenediamine (TMED) and other; pyridines, C 5 R n H 5-n N, with R = C 1 -C 8 group, n = 0-5; dipyridines, for instance 2,2′-dipyridine and other; phenanthrolines; imines, RCH=NR′, with R and R′ = C 1 -C 8 group; diimines, R-N=CH-CH=N-R′, with R and R′ = C 1 -C 8 group. The synthesis of the barium-, strontium- and calcium-β-diketonate ligand complexes proceeds by a reaction of the required amount of complexing ligand with the appropriate barium-, strontium- or calcium-β-diketonate in an inert solvent such as toluene or pentane. It has been found that the stability of the compounds is markedly improved when at least one of the side chains R′ and R″ of the β-diketonate contains a fluorine-substituted alkyl and/or aryl group. In a preferred realisation of the invention, at least one of the side chains R′ and R″ consists of the alkyl groups CF 3 and/or n-C 3 F 7 . With compounds according to this preferred realisation, very stable and volatile barium-, strontium- and calcium-β-diketonate ligand complexes at elevated temperatures and/or lowered pressures are formed. The following structure formulas give a number of representative examples of barium, strontium and calcium compounds according to the invention: 1 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 2{CH 3 OCH 2 CH 2 OCH 3 }. 2 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 3{(CH 3 ) 2 NC(O)H}. 3 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 2{(CH 3 ) 2 NCH 2 CH 2 N(CH 3 ) 2 }. 4 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 2{CH 3 O(CH 2 CH 2 O) 2 CH 3 }. 5 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 3 CH 3 }. 6 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 }. 7 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {(CH 2 CH 2 O) 6 }. 8 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 6 CH 3 }. 9 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 6{CH 3 S(O)CH 3 }. 10 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 9{(CH 2 ) 4 SO 2 }. 11 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {o-(2-C 5 H 4 N)C 5 H 4 N}. 12 . Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {HO(CH 2 CH 2 O) 4 CH 3 }. 13 . Ba{CF 3 C(O)CHC(O)CH 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 }. 14 . Ba{CF 3 C(O)CHC(O)CH 3 } 2 . {(CH 2 CH 2 O) 6 }. 15 . Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 }. 16 . Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 . {CH 3 O(CH 2 CH 2 O) 6 CH 3 }. 17 . Sr{CF 3 C(O)CHC(O)CF 3 } 2 . 2{CH 3 OCH 2 CH 2 OCH 3 }. 18 . Sr{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 }. 19 . Ca{CF 3 C(O)CHC(O)CF 3 } 2 . 2{CH 3 OCH 2 CH 2 OCH 3 }. 20 . Ca{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 3 CH 3 }. 21 . Ca{CF 3 C(O)CHC(O)CH 3 } 2 . {CH 3 O(CH 2 CH 2 O) 3 CH 3 }. The volatility of these compounds and the corresponding barium-, strontium- and calcium-β-diketonates are shown in Table 1. As the table shows, these compounds sublime at reduced pressure (0.01-0.5 mm Hg) at temperatures between 85°C and 180°C. This means that they are especially appropriate as precursor for so-called metal-organic chemical vapor deposition (MO-CVD) of materials containing the corresponding metals. The invention also deals with a method for the preparation of layered materials which contain barium, strontium or calcium oxides or fluorides, by means of a deposition technique. Such a method is known, for instance from the publication of Dickinson et al., mentioned above. With the known methods, especially MO-CVD, one encounters problems with the deposition of some barium, strontium or calcium containing layered structures, because of the low volatility and the rapid decomposition of the precursor from which the deposition should take place. The invention aims at eliminating those problems and thereto provides a method, characterized in that with the deposition technique one starts with volatile organic barium, strontium or calcium compounds according to the invention described above, corresponding to the desired barium, strontium or calcium oxides or fluorides. Without excluding other deposition techniques such as dip coating, (plasma)-spray-pyrolysis and spin coating, the compounds and procedures according to the invention are particularly appropriate when applied with MO-CVD. By using volatile and stable compounds according to the invention, in a MO-CVD process, barium, strontium and/or calcium oxide-containing materials can be prepared easily with this technique. The applicability of MO-CVD for such materials is of importance especially for preparation of and research on recently discovered mixed metal oxides, super-conductive at relative high temperatures. In an alternative realisation of the method according to the invention, the organic barium, strontium and calcium compounds are formed during the MO-CVD process by adding a coordinating ligand in liquid or vapor phase to the barium-, strontium- or calcium-β-diketonate. Also with this method an increased and more constant mass transport of the barium-, strontium- and calcium-β-diketonate can be obtained. IMPLEMENTATION EXAMPLES The following examples illustrate the methods and chemical preparation of the compounds of this invention and as such are not to be constructed as limiting the scope thereof. All reactions are carried out in a dry atmosphere and at room temperature unless otherwise stated. Example 1 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 2{CH 3 OCH 2 CH 2 OCH 3 }. ( 1 ) 0.4 ml of CH 3 OCH 2 CH 2 OCH 3 (glyme, DME) is added to a stirred suspension of 0.54 g (0.98 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 in 15 ml of toluene. Stirring is continued for 0.5 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 30°C. The beige coloured solid product thus obtained is dried in vacuo at room temperature for 4 h. Yield: 0.6 g of 1 (84.5 %). Melting point: 45°-47°C. 1 H NMR in C 6 D 6 : δ(CH 3 ) 3.01 ppm (s) δ(CH 2 CH 2 ) 2.87 ppm (s) δ(CH) 6.18 ppm (s). Elemental analysis: found (calculated) (%) C 29.14 (29.54); H 3.00 (3.01); F 30.16 (31.18). Example 2 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 3{(CH 3 ) 2 NC(O)H}. ( 2 ) 0.58 g (7.98 mmol) of (CH 3 ) 2 NC(O)H (DMF) is added dropwise to a stirred suspension of 0.55 g (0.99 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 in 15 ml of toluene. Stirring is continued for about 0.5 h. The clear reaction mixture is evaporated to dryness under reduced pressure at 30°C. The residue is dissolved in 20 ml of toluene and the clear solution is evaporated to dryness at reduced pressure at 30°C. The beige coloured residue (a syrup) is dried in vacuo at room temperature for 4 h. Yield: 0.56 g of 2 (73.6 %). 1 H NMR in C 6 D 6 : δ(CH 3 ) 2.11 and 2.49 ppm (s) δ(CH-DMF) 7.76 ppm (s) δ(CH) 6.09 ppm (s). Elemental analysis: found (calculated) (%) C 29.40 (29.60); H 2.94 (2.99); N 4.98 (5.45). Example 3 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 2{(CH 3 ) 2 NCH 2 CH 2 N(CH 3 ) 2 }. ( 3 ) 0.36 g (3.12 mmol) of (CH 3 ) 2 NCH 2 CH 2 N(CH 3 ) 2 (TMED) is added dropwise to a stirred suspension of 0.43 g (0.78 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 in 15 ml of toluene. Stirring is continued for about 0.5 h. The clear reaction mixture is evaporated to dryness under reduced pressure at 30°C. The beige coloured solid residue is dried in vacuo at room temperature for 4 h. Yield: 0.57 g of 3 (93.4 %). Melting point: 118°-120°C. 1 H NMR in C 6 D 6 : δ(CH 3 ) 1.94 ppm (s) δ(CH 2 CH 2 ) 1.84 ppm (s) δ(CH) 6.28 ppm (s). Elemental analysis: found (calculated) (%) C 33.64 (33.70); H 4.43 (4.34); N 7.02 (7.15). Example 4 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 2{CH 3 O(CH 2 CH 2 O) 2 CH 3 }. ( 4 ) 0.41 g (3.05 mmol) of CH 3 O(CH 2 CH 2 O) 2 CH 3 (diglyme) is added dropwise to a stirred suspension of 0.84 g (1.52 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 in 15 ml of toluene. Stirring is continued for about 1 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 30°C. The colourless solid residue is dried in vacuo at room temperature for 4 h. Yield: 1.16 g of 4 (93.6 %). Melting point: 110°-112°C. 1 H NMR in C 6 D 6 : δ(CH 3 ) 3.06 ppm (s) δ(CH 2 CH 2 ) 3.14 ppm (m) δ(CH) 6.22 ppm (s). Elemental analysis: found (calculated) (%) C 32.30 (32.22); H 3.66 (3.66); F 27.92 (27.83). Example 5 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 3 CH 3 }. ( 5 ) 0.24 g (1.36 mmol) of CH 3 O(CH 2 CH 2 O) 3 CH 3 (triglyme) is added dropwise to a stirred suspension of 0.75 g (1.36 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 in 20 ml of toluene. Stirring is continued for about 1 h. The almost clear reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 40°C. The colourless solid residue is recrystallized from a mixture of toluene and pentane and then dried in vacuo at room temperature for 4 h. Yield: 0.51 g of 5 (51.5 %). Melting point: 105°-107°C. 1 H NMR in C 6 D 6 : δ(CH 3 ) 3.00 ppm (s) δ(CH 2 CH 2 ) 2.94 ppm (m) δ(CH) 6.20 ppm (s). Elemental analysis: found (calculated) (%) C 29.67 (29.62); H 3.13 (2.74). Example 6 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 }. ( 6 ) 0.43 g (1.94 mmol) of CH 3 O(CH 2 CH 2 O) 4 CH 3 (tetraglyme) is added dropwise to a stirred suspension of 1.07 g (1.94 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 in 20 ml of toluene. Stirring is continued for about 1 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 30°C. The colourless solid residue is dried in vacuo at room temperature for 4 h. Yield: 1.42 g of 6 (94.7 %). Melting point: 145°-147°C. 1 H NMR in C 6 D 6 : δ(CH 3 ) 3.18 ppm (s) δ(CH 2 CH 2 ) 2.87 ppm (s) and 3.18 ppm (m) δ(CH) 6.23 ppm (s). Elemental analysis: found (calculated) (%) C 31.61 (31.03); H 3.36 (3.10). Example 7 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {(CH 2 CH 2 O) 6 }. ( 7 ) A solution of 0.306 g (1.16 mmol) of (CH 2 CH 2 O) 6 (18-crown-6) in 7 mlof toluene is added dropwise to a stirred suspension of 0.64 g (1.16 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 , in 15 ml of toluene. Stirring is continued for about 1 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 30°C. The colourless solid residue is dried in vacuo at room temperature for 4 h. Yield: 0.88 g of 7 (93.0 %). Melting point: 234°-236°C. 1 H NMR in C 6 D 6 : δ(CH 2 CH 2 ) 3.20 ppm (s) δ(CH) 6.23 ppm (s). Elemental analysis: found (calculated) (%) C 32.45 (32.38); H 3.36 (3.19). Example 8 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 6 CH 3 }. ( 8 ) 2.70 g (8.72 mmol) of CH 3 O(CH 2 CH 2 O) 6 CH 3 (hexaglyme) is added dropwise to a stirred suspension of 4.81 g (8.72 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 in 75 ml of toluene. Stirring is continued for about 1 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 40°C. The off-white solid residue is recrystallized from pentane. The colourless product is then dried in vacuo at 50°C for 4 h. Yield: 5.64 g of 8 (75.1 %). Melting point: 70°-72°C. 1 H NMR in C 6 D 6 : δ(CH 3 ) 3.11 ppm (s) δ(CH 2 CH 2 ) 3.17, 3.26, 3.32 and 3.40 ppm (m) δ(CH) 6.25 ppm (s). Elemental analysis: found (calculated) (%) C 33.35 (33.44); H 3.80 (3.72); F 26.25 (26.47). Example 9 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 6{CH 3 S(O)CH 3 }. ( 9 ) 0.75 g (9.58 mmol) of CH 3 S(O)CH 3 (DMSO) is added to a stirred suspension of 0.66 g (1.20 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 in 15 ml of toluene. Stirring is continued for about 1 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 40°C. The oily residue is washed thrice with 25 ml of pentane. The light yellow product (a syrup) is then dried in vacuo at room temperature for 4 h. Yield: 1.05 g of 9 (86.1 %). 1 H NMR in C 6 D 6 : δ(CH 3 ) 1.95 ppm (s) δ(CH) 6.28 ppm (s). Elemental analysis: found (calculated) (%) C 25.88 (25.88); H 3.83 (3.73); S 19.35 (18.88). Example 10 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 9{(CH 2 ) 4 SO 2 }. ( 10 ) 0.99 g (8.27 mmol) of (CH 2 ) 4 SO 2 (sulfolane) is added to a stirred suspension of 0.57 g (1.03 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 in 15 ml of toluene. Stirring is continued for about 1 h. The clear reaction mixture is evaporated to dryness under reduced pressure at 40°C. The oily residue is washed thrice with 25 ml of pentane. The light yellow product (an oil) is then dried in vacuo at room temperature for 4 h. Yield: 1.53 g of 10 (90.7 %). 1 H NMR in CD 3 C(O)CD 3 : δ(CH 2 S) 2.76 ppm (m) δ(CH 2 CH 2 ) 1.90 ppm (m) δ(CH) 5.84 ppm (s). Elemental analysis: found (calculated) (%) C 33.97 (33.82); H 4.72 (4.53); S 17.72 (17.68). Example 11 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {o-(2-C 5 H 4 N)C 5 H 4 N}. ( 11 ) 0.70 g (4.46 mmol) of o-(2-C 5 H 4 N)C 5 H 4 N (2,2′-dipyridine) is added to a stirred suspension of 0.82 g (1.49 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 in 30 ml of toluene. Stirring is continued for 0.5 h at room temperature and 0.5 h at 55°C. After cooling to room temperature the precipitated colourless product is filtered off and washed with toluene and pentane. The product is then dried in vacuo above KOH for 3 days. Yield: 0.9 g of 11 (85.7 %). Melting point: 214°-216°C. 1 H NMR in CD 3 C(O)CD 3 : δ(C 5 H 4 ) 7.40, 7.93, 8.55 and 8.83 ppm (m) δ(CH) 5.66 ppm (s). Elemental analysis: found (calculated) (%) C 33.78 (33.93); H 1.52 (1.41); H 3.93 (3.96). Example 12 Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {HO(CH 2 CH 2 O) 4 CH 3 }. ( 12 ) 0.35 g (1.67 mmol) of HO(CH 2 CH 2 O) 4 CH 3 (tetraethyleneglycol monomethyl ether) is added dropwise to a stirred suspension of 0.92 g (1.67 mmol) of Ba{CF 3 C(O)CHC(O)CF 3 } 2 in 20 ml of toluene. Stirring is continued for about 1 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 40°C. The off-white residue is stirred with 20 ml of pentane for 0.5 h and then filtered off. The colourless product is then dried in vacuo at room temperature for 4 h. Yield: 1.07 g of 12 (84.9 %). Melting point: 144°-146°C. 1 H NMR in C 6 D 5 CD 3 : δ(CH 3 ) 3.13 ppm (s) δ(CH 2 CH 2 ) 2.90-3.22 ppm (m) δ(OH) 2.78 ppm (s;br) δ(CH) 6.19 ppm (s). Elemental analysis: found (calculated) (%) C 30.04 (30.03); H 2.98 (2.90). Example 13 Ba{CF 3 C(O)CHC(O)CH 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 }. ( 13 ) 0.22 g (1.00 mmol) of CH 3 O(CH 2 CH 2 O) 4 CH 3 (tetraglyme) is added dropwise to a stirred suspension of 0.44 g (1.00 mmol) of Ba{CF 3 C(O)CHC(O)CH 3 } 2 in 10 ml of toluene. Stirring is continued for about 1 h. The resulting solution is evaporated to dryness under reduced pressure at 40°C. The solid residue is stirred with 20 ml of pentane for 0.5 h and then filtered off. The colourless product is then dried in vacuo at room temperature for 4 h. Yield: 0.59 g of 13 (89.4 %). Melting point: 140°-142°C. 1 H NMR in C 6 D 6 : δ(OCH 3 ) 3.30 ppm (s) δ(CH 2 CH 2 ) 2.98, 3.20 and 3.36 ppm (m) δ(CH 3 ) 1.89 ppm (s) δ(CH) 5.80 ppm (s). Elemental analysis: found (calculated) (%) C 36.02 (36.07); H 4.58 (4.51). Example 14 Ba{CF 3 C(O)CHC(O)CH 3 } 2 . {(CH 2 CH 2 O) 6 }. ( 14 ) 0.26 g (1.00 mmol) of (CH 2 CH 2 O) 6 (18-crown-6) is added to a stirred solution of 0.44 g (1.00 mmol) of Ba{CF 3 C(O)CHC(O)CH 3 } 2 in a mixture of 15 ml of toluene and 5 ml of ethanol. Stirring is continued for about 1 h. The solution is evaporated to dryness under reduced pressure at 40 °C. The solid residue is stirred with 25 ml of pentane for 0.5 h and then filtered off. The off-white product is then dried in vacuo at room temperature for 4 h. Yield: 0.66 g of 14 (94.0 %). Melting point: 190°-192°C (dec). 1 H NMR in CDCl 3 : δ(CH 2 CH 2 ) 3.78 ppm (s) δ(CH 3 ) 1.99 ppm (s) δ(CH) 5.43 ppm (s). Elemental analysis: found (calculated) (%) C 37.04 (37.32); H 4.53 (4.52). Example 15 Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 . ( 15 ) 0.51 g (2.28 mmol) of CH 3 O(CH 2 CH 2 O) 4 CH 3 (tetraglyme) is added dropwise to a stirred solution of 1.70 g (2.28 mmol) of Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 in 60 ml of toluene. Stirring is continued for about 1 h. The solution is evaporated to dryness under reduced pressure at 40°C. The residue is dissolved in 20 ml of pentane and this solution is also evaporated to dryness under reduced presure at 30°C. The off-white residue (a syrup) is cooled to -20°C upon which the product solidified. The product is then dried in vacuo at room temperature for 4 h. Yield: 1.94 g of 15 (89.8 %). Melting point: 48°-50°C. 1 H NMR in CDCl 3 : δ(OCH 3 ) 3.33 ppm (s) δ(CH 2 CH 2 ) 3.46, 3.56, 3.71 and 3.79 ppm (m) δ(t-Bu) 1.11 ppm (s) δ(CH) 5.65 ppm (s). Elemental analysis: found (calculated) (%) C 38.33 (37.92); H 4.52 (4.42); F 27.48 (28.02). Example 16 Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 . {CH 3 O(CH 2 CH 2 O) 6 CH 3 }. ( 16 ) 0.45 g (1.44 mmol) of CH 3 O(CH 2 CH 2 O) 6 CH 3 (hexaglyme) is added dropwise to a stirred suspension of 1.05 g (1.44 mmol) of Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 in 15 ml of pentane. Stirring is continued for 0.5 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 30°C. The off-white product is then dried in vacuo at room temperature for 4 h. Yield: 1.43 g of 16 (96.0 %). Melting point: 68°-70°C. 1 H NMR in CDCl 3 : δ(OCH 3 ) 3.31 ppm (s) δ(CH 2 CH 2 ) 3.49, 3.61, 3.68 and 3.69 ppm (m) δ(t-Bu) 1.11 (s) δ(CH) 5.63 (s). Elemental analysis: found (calculated) (%) C 39.06 (39.33); H 4.59 (4.82). Example 17 Sr{CF 3 C(O)CHC(O)CF 3 } 2 . 2{CH 3 OCH 2 CH 2 OCH 3 }. ( 17 ) 0.54 ml of CH 3 OCH 2 CH 2 OCH 3 (glyme, DME) is added dropwise to a stirred suspension of 0.66 g (1.32 mmol) of Sr{CF 3 C(O)CHC(O)CF 3 } 2 in 15 ml of toluene. Stirring is continued for about 0.5 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 30°C. The colourless solid residue is dried in vacuo at room temperature for 4 h. Yield: 0.84 g of 17 (94.4 %). Melting point: 80°-82°C. 1 H NMR in C 6 D 6 : δ(CH 3 ) 3.08 ppm (s) δ(CH 2 CH 2 ) 2.81 ppm (s) δ(CH) 6.27 ppm (s). Elemental analysis: found (calculated) (%) C 31.66 (31.69); H 3.27 (3.32); F 33.51 (33.45). Example 18 Sr{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 . ( 18 ) 4.53 g (20.39 mmol) of CH 3 O(CH 2 CH 2 O) 4 CH 3 (tetraglyme) is added dropwise to a stirred suspension of 10.23 g (20.39 mmol) of Sr{CF 3 C(O)CHC(O)CF 3 } 2 in 160 ml of toluene. Stirring is continued for 1 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 40°C. The solid residue is stirred with 100 ml of pentane for 0.5 h and then filtered off. The colourless product is then dried in vacuo at room temperature for 4 h. Yield: 12.91 g of 18 (87.5 %). Melting point: 137°-139°C. 1 H NMR in CDCl 3 : δ(CH 3 ) 3.34 ppm (s) δ(CH 2 CH 2 ) 3.46, 3.57, 3.76 and 3.79 ppm (m) δ(CH) 5.88 ppm (s). Elemental analysis: found (calculated) (%) C 33.28 (33.17); H 3.34 (3.32). Example 19 Ca{CF 3 C(O)CHC(O)CF 3 } 2 . 2{CH 3 OCH 2 CH 2 OCH 3 }. ( 19 ) 1.2 ml of CH 3 OCH 2 CH 2 OCH 3 (glyme, DME) is added dropwise to a stirred suspension of 1.31 g (2.88 mmol) of Ca{CF 3 C(O)CHC(O)CF 3 } 2 in 15 ml of toluene. Stirring is continued for about 0.5 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 30°C. The colourless solid residue is dried in vacuo at room temperature for 4 h. Yield: 1.74 g of 19 (95.1 %). Melting point: 80°-82°C. 1 H NMR in C 6 D 6 : δ(CH 3 ) 3.11 ppm (s) δ(CH 2 CH 2 ) 2.80 ppm (s) δ(CH) 6.21 ppm (s). Elemental analysis: found (calculated) (%) C 33.52 (34.07); H 3.53 (3.47); F 35.36 (35.96). Example 20 Ca{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 3 CH 3 }. ( 20 ) 4.12g (23.12 mmol) of CH 3 O(CH 2 CH 2 O) 3 CH 3 (triglyme) is added dropwise to a stirred suspension of 10.50 g (23.12 mmol) of Ca{CF 3 C(O)CHC(O)CF 3 } 2 in 150 ml of toluene. Stirring is continued for 1 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 40°C. The solid residue is stirred with 100 ml of pentane for 0.5 h and then filtered off. The colourless product is then dried in vacuo at room temperature for 4 h. Yield: 10.90 g of 20 (74.6 %). Melting point: 120°-122°C. 1 H NMR in CDCl 3 : δ(CH 3 ) 3.29 ppm (s) δ(CH 2 CH 2 ) 3.53, 3.65 ppm (m) and 3.91 ppm (s) δ(CH) 5.94 ppm (s). Elemental analysis: found (calculated) (%) C 34.22 (34.17); H 3.22 (3.16); F 35.61 (36.07). Example 21 Ca{CF 3 C(O)CHC(O)CH 3 } 2 . {CH 3 O(CH 2 CH 2 O) 3 CH 3 }. ( 21 ) 0.18 g (1.00 mmol) of CH 3 O(CH 2 CH 2 O) 3 CH 3 (triglyme) is added dropwise to a stirred suspension of 0.35 g (1.00 mmol) of Ca{CF 3 C(O)CHC(O)CH 3 } 2 in 25 ml of toluene. Stirring is continued for 1 h. The slightly turbid reaction mixture is filtered and the clear filtrate is evaporated to dryness under reduced pressure at 40°C. The light yellow product solidifies on drying in vacuo at room temperature for 4 h. Yield: 0.51 g of 21 (97.3 %). Melting point: 65°-67°C. 1 H NMR in C 6 D 6 : δ(OCH 3 ) 3.11 ppm (s) δ(CH 2 CH 2 ) 3.11, 3.24 ppm (m) and 3.33 ppm (s) δ(CH 3 ) 1.86 ppm (s) δ(CH) 5.76 ppm (s). Elemental analysis: found (calculated) (%) C 41.35 (41.22); H 5.03 (4.96). Example 22 Sublimation of Ba-, Sr- and Ca-β-diketonate-ligand complexes. Sublimation of various Ba-, Sr- and Ca-β-diketonate ligand complexes is performed at reduced pressure (0.5-0.01 mm Hg) and temperatures of 85°-180°C. Results are presented in Table I. Example 23 Co-evaporation of Ba{CF 3 C(O)CHC(O)CF 3 } 2 with CH 3 OCH 2 CH 2 OCH 3 (glyme, DME) as the neutral coordinating ligand. A dry N 2 flow (6 litres per hour) was led over Ba{CF 3 C(O)CHC(O)CF 3 } 2 (100 mg) at 225°C for 3 hours and then led through a cold trap (-80°C) in order to condense any transported Ba-compound. However, after the experiment, no barium could be detected in the cold trap. When, instead of a dry N 2 flow, a N 2 flow (6 litres per hour), saturated at 25°C with CH 3 OCH 2 CH 2 OCH 3 (dimethoxyethane) is led over Ba{CF 3 C(O)CHC(O)CF 3 } 2 (100 mg) at 225°C for 3 hours, the condensate in the cold trap contains 5 mg of barium as Ba{CF 3 C(O)CHC(O)CF 3 } 2 . 2{CH 3 OCH 2 CH 2 OCH 3 } ( 1 ) dissolved in CH 3 OCH 2 CH 2 OCH 3 . In a similar experiment, performed with Ba{CF 3 C(O)CHC(O)CF 3 } 2 at a temperature of 145°C, after 2 hours the condensate contains about 1 mg of barium. Example 24 Co-evaporation of Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 with CH 3 OCH 2 CH 2 OCH 3 (glyme, DME) as the coordinating neutral ligand. A dry N 2 flow (6 litres per hour) was led over Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 (100 mg) at 150°C for 1 hour and 45 minutes and then led through a cold trap (-80°C) in order to condense any transported Ba-compound. After the experiment no barium could be detected in the cold trap. When however, instead of a dry N 2 flow, a N 2 flow (6 litres per hour), saturated at 25°C with CH 3 OCH 2 CH 2 OCH 3 (dimethoxyethane), is led over Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 (100 mg) at 150°C for 2.5 hours, the condensate in the cold trap contains 0.1 mg of barium. Example 25 MOCVD deposition of BaF 2 from Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 } ( 6 ). In a hot-wall MOCVD apparatus, a dry N 2 flow (97 sccm) was led over Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 } at temperatures ranging from 105°C to 175°C, and mixed with N 2 (1150 sccm) and O 2 (415 sccm) before entering the reactor chamber. Deposition was performed on a polycrystalline substrate of yttria-stabilized zirconia (YSZ) at 800°C; pressure 10-20 torr. X-ray diffraction analysis (XRD) after deposition proved the deposit to be BaF 2 . Growth rates varied from 1.3 ug/cm 2 /min (T evaporator 105°C) to 65 ug/cm 2 /min (T evaporator 175°C). Example 26 MOCVD deposition of SrF 2 from Sr{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 } ( 18 ). In a hot-wall MOCVD apparatus, a dry N 2 flow (100 sccm) was led over Sr{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 } at 146°C, and mixed with N 2 (733 sccm) and O 2 (833 sccm) before entering the reactor chamber. Deposition was performed on YSZ at 800°C; pressure 15 torr. XRD after deposition proved the deposit to be SrF 2 . The growth rate was 30 ug/cm 2 /min. Example 27 MOCVD deposition of CaF 2 from Ca{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 3 CH 3 } ( 20 ). In a hot-wall MOCVD apparatus, a dry N 2 flow (100 sccm) was led over Ca{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 3 CH 3 } at 146°C, and mixed with N 2 (733 sccm) and O 2 (833 sccm) before entering the reactor chamber. Deposition was performed on YSZ at 800°C; pressure 15 torr. XRD after deposition proved the deposit to be CaF 2 . The growth rate was 18 ug/cm 2 /min. Example 28 MOCVD deposition of YBa 2 Cu 3 O 7-x from Y{(CH 3 ) 3 CC(O)CHC(O)C(CH 3 ) 3 } 3 , Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 } ( 6 ) and Cu{(CH 3 ) 3 CC(O)CHC(O)C(CH 3 ) 3 } 2 . In a hot-wall MOCVD apparatus, three dry N 2 flows (each 97 sccm) were led over Y{(CH 3 ) 3 CC(O)CHC(O)C(CH 3 ) 3 } 3 , Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 } and Cu{(CH 3 ) 3 CC(O)CHC(O)C(CH 3 ) 3 } 2 , at a temperature of resp. 163.3°C, 147.2°C and 147.2°C for the Y, Ba and Cu compound. These flows were mixed before entering the reactor chamber together with flows of N 2 (1825 sccm) and O 2 (2100 sccm). The latter gas stream had been led beforehand through a water vaporiser (T water 50°C). Depositions were performed on single-crystal MgO substrates at 800°C and 900°C; total gas pressure 12 torr. XRD after deposition proved the deposits to contain YBa 2 Cu 3 O 7-x , oriented along the c-axis. Example 29 MOCVD deposition of BaO from Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 } ( 6 ). In a hot-wall MOCVD apparatus, a dry N 2 flow (97 sccm) was led over Ba{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 } at 164.5°C, and mixed with N 2 (2008 sccm) and O 2 (2100 sccm) before entering the reactor chamber. The latter gas stream had been led beforehand through a water vaporiser ( T water 20.5 °C). Deposition was performed on a single-crystal MgO with (100) orientation at 893°C; pressure 42 torr. XRD after deposition proved the deposit to contain BaO. No fluor was detected by X-ray Photoelectron Spectroscopy (XPS). The growth rate was 8 ug/cm 2 /min. Example 30 MOCVD deposition of SrO from Sr{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 } ( 18 ). In a hot-wall MOCVD apparatus, a dry N 2 flow (100 sccm) was led over Sr{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 4 CH 3 } at 138.1°C, and mixed with N 2 (733 sccm) and O 2 (833 sccm) before entering the reactor chamber. The latter gas stream had been led beforehand through a water vaporiser (T water 50.2°C). Deposition was performed on polycrystalline YSZ at 801.4°C; pressure 25 torr. XRD after deposition proved the deposit to contain SrO. The growth rate was 11 ug/cm 2 /min. Example 31 MOCVD deposition of CaO from Ca{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 3 CH 3 } ( 20 ). In a hot-wall MOCVD apparatus, a dry N 2 flow (100 sccm) was led over Ca{CF 3 C(O)CHC(O)CF 3 } 2 . {CH 3 O(CH 2 CH 2 O) 3 CH 3 } at 139.1°C, and mixed with N 2 (733 sccm) and O 2 (833 sccm) before entering the reactor chamber. The latter gas stream had been led beforehand through a water vaporiser (T water 50.2°C). Deposition was performed on polycrystalline YSZ at 800.3°C.; pressure 25 torr. XRD after deposition proved the deposit to contain CaO. The growth rate was 10 ug/cm 2 /min. Volatility of some compounds according to the invention and of some corresponding barium-, strontium- and calcium-β-diketonates upon sublimation in vacuo. The numbers refer to the numbers of the structure formulas in the opening description. Compound (100 mg) P (mm Hg) T (°C) Sublimed (% after 1 hour) Ba{CF 3 C(O)CHC(O)CF 3 } 2 0.5 150 0 1 0.5 150 5 2 0.02 160 5 3 0.03 125 13 4 0.02 165 40 5 0.03 145 60 6 0.03 150 95 7 0.03 165 95 8 0.02 145 95 9 0.01 180 48 10 0.01 170 18 11 0.02 170 11 12 0.02 145 95 Ba{CF 3 C(O)CHC(O)CH 3 } 2 0.02 150 0 13 0.03 145 13 14 0.02 170 16 Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 0.02 150 0 15 0.02 155 80 16 0.02 150 80 Sr{CF 3 C(O)CHC(O)CF 3 } 2 0.06 95 0 17 0.06 95 25 18 0.01 115 95 Ca{CF 3 C(O)CHC(O)CF 3 } 2 0.05 85 0 19 0.05 85 50 20 0.02 100 95 Ca{CF 3 C(O)CHC(O)CH 3 } 2 0.02 135 0 21 0.02 135 11

Claims: A volatile, thermally stable alkaline earth metal β-diketonate donor ligand complex of the formula where M is Ba, Ca or Sr; R' and R'', which may be the same or different, are alkyl or substituted alkyl, aryl or substituted aryl groups, the said substituted alkyl and aryl groups containing as the only substituent(s) one or more fluorine atoms; L is a neutral oxygen donor ligand selected from triglyme, tetraglyme, hexaglyme, 18-crown-6 and tetraethyleneglycol monomethyl ether; and m has a value of from 1-6. A volatile, thermally stable alkaline earth metal β-diketonate donor ligand complex of the formula where M is Ba, Ca or Sr; R' and R'', which may be the same or different, are alkyl or substituted alkyl, aryl or substituted aryl groups, the said substituted alkyl and aryl groups containing as the only substituent(s) one or more fluorine atoms, and with the further proviso that at least one of the groups R' and R'' is such a substituted group: L is a neutral oxygen donor ligand selected from triglyme, tetraglyme, hexaglyme, 18-crown-6 and tetraethyleneglycol monomethyl ether; and m has a value of from 1 - 6. A volatile, thermally stable alkaline earth metal β-diketonate donor ligand complex according to claim 1 or claim 2 wherein the alkyl group is -CH 3 or -C (CH 3 ) 3 . A volatile, thermally stable alkaline earth metal β-diketonate donor ligand complex according to any one of claims 1 to 3 wherein at least one of the groups R' and R'' is -CF 3 or n-C 3 F 7 . A volatile, thermally stable alkaline earth metal β-diketonate donor ligand complex according to claim 1 or claim 2, where the β-diketonate is any one of: hexafluoroacetylacetone 1,1,1,-trifluoroacetylacetone 1,1,1,2,2,3,3-heptafluoro-8,8-dimethylocta-4,6-dione. A volatile, thermally stable alkaline earth metal β-diketonate donor ligand complex according to claim 1 or claim 2, being any one of the following: 1. Ba{CF 3 C(O)CHC(O)CF 3 } 2 {CH 3 O(CH 2 CH 2 O) 3 CH 3 } 2. Ba{CF 3 C(O)CHC(O)CF 3 } 2 {CH 3 O(CH 2 CH 2 O) 4 CH 3 } 3. Ba{CF 3 C(O)CHC(O)CF 3 } 2 {(CH 2 CH 2 O) 6 } 4. Ba{CF 3 C(O)CHC(O)CF 3 } 2 {CH 3 O(CH 2 CH 2 O) 6 CH 3 } 5. Ba{CF 3 C(O)CHC(O)CF 3 } 2 {HO(CH 2 CH 2 O) 4 CH 3 } 6. Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 } 2 {CH 3 O(CH 2 CH 2 O) 4 CH 3 } 7. Ba{CF 3 CF 2 CF 2 C(O)CHC(O)C(CH 3 ) 3 }2 {CH 3 O(CH 2 CH 2 O) 6 CH 3 } 8. Sr{CF 3 C(O)CHC(O)CF 3 } 2 {CH 3 O(CH 2 CH 2 O) 4 CH 3 } 9. Ca{CF 3 C(O)CHC(O)CF 3 } 2 {CH 3 O(CH 2 CH 2 O) 3 CH 3 } A method for the preparation of layered barium, calcium or strontium deposits, wherein there is used a volatile, thermally stable complex of barium, calcium or strontium as claimed in any one of claims 1 to 6. A method according to claim 7, wherein the said deposit is formed by a metal-organic vapour deposition (MO-CVD) process employing the said complex as a volatile source of barium, calcium or strontium. A method according to claim 7, wherein one starts with the preformed complex and transports that preformed complex into the vapour phase. A method according to claim 7 wherein the organic barium, strontium or calcium compounds are formed during a MO-CVD process by adding the coordinating ligand to the barium-, strontium- or calcium-β-diketonate in the liquid or vapour phase.

Inventors: MACKOR ADRIANUS, MEINEMA HARMEN ANNE, SPEE CAROLUS IDA MARIA ANTONIU, TIMMER KLAAS, MACKOR, ADRIANUS, MEINEMA, HARMEN ANNE, SPEE, CAROLUS IDA MARIA ANTONIUS, TIMMER, KLAAS
Applicants: ASS OCTEL, THE ASSOCIATED OCTEL COMPANY LIMITED
Application year: 1990
Main classification: C07F3
IPC codes: C23C16, C07F3, C07C315, C07C211, C07D323, C07C45, C07C231, C07D471, C07D213, C07C49, C30B25, C07C317, C07C209, C07C233