Organic Electronic Component, use of a Zinc Complex as a P-Dopant for Organic Electronic Matrix Materials

Abstract

An organic electronic component and a method for making an organic electronic component with a p-dopant are disclosed. In an embodiment, the component includes a matrix containing a zinc complex as a p-dopant, the zinc complex containing at least one ligand L of the following structure: formula (I) wherein R.sup.1 and R.sup.2 can be oxygen, sulphur, selenium, NH or NR.sup.4 independently selected from one another, wherein R.sup.3 may comprise alkyl, long-chain alkyl, cycloalkyl, halogen-alkyl, aryl, arylene, halogen-aryl, heteroaryl, heteroarylene, heterocyclic-alkylene, heterocycloalkyl, halogen-heteroaryl, alkenyl, halogen-alkenyl, alkynyl, halogen-alkynyl, ketoaryl, halogen-ketoaryl, ketoheteroaryl, ketoalkyl, halogen-ketoalkyl, ketoalkenyl, halogen-ketoalkenyl, halogen-alkyl-aryl or halogen-alkyl-heteroaryl, and wherein R.sup.4 is selected from the group consisting of alkyl and aryl which can be bonded to R.sup.3.

Claims

1-15. (canceled)

16. An organic electronic component comprising: a matrix comprising a zinc complex as a p-dopant, the zinc complex containing at least one ligand L of the following structure: ##STR00016## wherein R.sup.1 and R.sup.2 include oxygen, sulfur, selenium, NH or NR.sup.4 selected independently from one another, wherein R.sup.3 is selected from the group consisting of alkyl, long-chain alkyl, cycloalkyl, haloalkyl, aryl, arylene, haloaryl, heteroaryl, heteroarylene, heterocycloalkylene, heterocycloalkyl, haloheteroaryl, alkenyl, haloalkenyl, alkinyl, haloalkinyl, ketoaryl, haloketoaryl, ketoheteroaryl, ketoalkyl, haloketoalkyl, ketoalkenyl, haloketoalkenyl, haloalkylaryl and haloalkylheteroaryl, wherein R.sup.4 is selected from the group consisting of alkyl and aryl and is bondable to R.sup.3, wherein one or more non-adjacent CH.sub.2 groups are replaceable by —O—, —S—, —NH—, —NR.sup.ooo—, —SiR.sup.oR.sup.oo—, —CO—, —COO—, —COR.sup.oOR.sup.oo—, —OCO—, —OCO—O—, —SO.sub.2—, —S—CO—, —CO—S—, —O—CS—, —CS—O—, —CY1═CY2 or —C≡C-independently from one another in such a way that O and/or S atoms are not directly bonded to one another, and wherein O and/or S atoms are replaceable with aryl or heteroaryl containing 1 to 30 C atoms.

17. The component according to claim 16, wherein R.sup.3 is selected from the group consisting of haloalkyl, haloaryl, haloheteroaryl, haloalkylaryl and haloalkylheteroaryl, and wherein the halogen is fluorine.

18. The component according to claim 16, wherein R.sup.3 is selected from the group consisting of: ##STR00017## wherein Y.sup.1-Y.sup.5 are selected independently of one another from the group consisting of C—H, C-D, C—F, C—NO.sub.2, C—CN, C-halogen, C-pseudohalogen, N and C—C.sub.nF.sub.2n+1 with n=1 to 10.

19. The component according to claim 16, wherein R.sup.3 is selected from the group consisting of: ##STR00018## wherein Y.sup.1-Y.sup.7 are selected independently of one another from the group consisting of C—H, C-D, C—F, C—NO.sub.2, C—CN, C-halogen, C-pseudohalogen, N and C—C.sub.nF.sub.2n+1 with n=1 to 10.

20. The component according to claim 16, wherein R.sup.3 is selected from the group consisting of: ##STR00019## wherein Y.sup.1-Y.sup.7 are selected independently of one another from the group consisting of C—H, C-D, C—F, C—NO.sub.2, C—CN, C-halogen, C-pseudohalogen and C—C.sub.nF.sub.2n+1 with n=1 to 10.

21. The component according to claim 16, wherein both R.sup.1 and R.sup.2 are oxygen.

22. The component according to claim 16, wherein the zinc complex further comprises at least one further ligand L.sup.C, which is bonded to zinc via a carbon atom.

23. The component according to claim 22, wherein the at least one ligand L.sup.C is a substituted, unsubstituted, branched, linear or cyclic alkyl, or a substituted, unsubstituted aryl or heteroaryl.

24. The component according to claim 16, wherein zinc has the coordination number 4, 5 or 6.

25. The component according to claim 16, wherein the zinc complex is a trinuclear or pentanuclear metal complex.

26. The component according to claim 16, wherein the zinc complex is a polynuclear metal complex, and wherein the at least one ligand L coordinately bonds two metal atoms.

27. The component according to claim 16, wherein the zinc complex is a polynuclear metal complex comprising at least two ligands L, wherein at least one of the ligands L coordinately bonds two metal atoms, and wherein at least one further ligand L is bonded terminally to a metal center of the zinc complex.

28. The component according to claim 16, wherein the zinc complex comprises at least two zinc atoms.

29. The component according to claim 16, wherein the zinc complex further comprises a metal different from zinc.

30. A method for making an electronic component, the method comprising: doping a matrix material of the electronic component with a p-dopant, wherein the p-dopant comprises a zinc complex comprising at least one ligand L of the following structure: ##STR00020## wherein R.sup.1 and R.sup.2 are be oxygen, sulfur, selenium, NH or NR.sup.4 selected independently from one another, wherein R.sup.3 is selected from the group consisting of alkyl, long-chain alkyl, cycloalkyl, haloalkyl, aryl, arylene, haloaryl, heteroaryl, heteroarylene, heterocycloalkylene, heterocycloalkyl, haloheteroaryl, alkenyl, haloalkenyl, alkinyl, haloalkinyl, ketoaryl, haloketoaryl, ketoheteroaryl, ketoalkyl, haloketoalkyl, ketoalkenyl, haloketoalkenyl, haloalkylaryl and haloalkylheteroaryl, wherein R.sup.4 is selected from the group consisting of alkyl and aryl and are bondable to R.sup.3, wherein one or more non-adjacent CH.sub.2 groups are replaceable by —O—, —S—, —NH—, —NR.sup.ooo—, —SiR.sup.oR.sup.oo—, —CO—, —COO—, —COR.sup.oOR.sup.oo—, —OCO—, —OCO—O—, —SO.sub.2—, —S—CO—, —CO—S—, —O—CS—, —CS—O—, —CY1═CY2 or —C≡C-independently from one another in such a way that O and/or S atoms are not directly bonded to one another, and wherein O and/or S atoms are replaceable with aryl or heteroaryl containing 1 to 30 C atoms.

31. The method according to claim 30, wherein the zinc complex is a mononuclear or a polynuclear complex and comprises a zinc atom in the oxidation stage II, and wherein the mononuclear zinc complex comprises the following structural unit: ##STR00021## or the polynuclear zinc complex comprises one of the following structural units: ##STR00022##

32. An organic electronic component comprising: a matrix comprising a mononuclear or a polynuclear zinc complex as a p-dopant, the zinc complex comprises a zinc atom in the oxidation stage II and contains at least one ligand L of the following structure: ##STR00023## wherein R.sup.1 and R.sup.2 are oxygen, sulfur, selenium, NH or NR.sup.4 selected independently from one another, wherein R.sup.3 is selected from the group consisting of alkyl, long-chain alkyl, cycloalkyl, haloalkyl, aryl, arylene, haloaryl, heteroaryl, heteroarylene, heterocycloalkylene, heterocycloalkyl, haloheteroaryl, alkenyl, haloalkenyl, alkinyl, haloalkinyl, ketoaryl, haloketoaryl, ketoheteroaryl, ketoalkyl, haloketoalkyl, ketoalkenyl, haloketoalkenyl, haloalkylaryl and haloalkylheteroaryl, wherein R.sup.4 is selected from the group consisting of alkyl and aryl and is bondable to R.sup.3, wherein one or more non-adjacent CH.sub.2 groups are replaceable by —O—, —S—, —NH—, —NR.sup.ooo—, —SiR.sup.oR.sup.oo—, —CO—, —COO—, —COR.sup.oOR.sup.oo—, —OCO—, —OCO—O—, —SO.sub.2—, —S—CO—, —CO—S—, —O—CS—, —CS—O—, —CY1═CY2 or —C≡C-independently from one another in such a way that O and/or S atoms are not directly bonded to one another, andindependently from one another in such a way that 0 and/or S atoms are not directly bonded to one another, wherein O and/or S atoms are replaceable with aryl or heteroaryl containing 1 to 30 C atoms, and wherein the mononuclear zinc complex comprises the following structural unit: ##STR00024## or the polynuclear zinc complex comprises one of the following structural units: ##STR00025##

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0221] Further details, features and advantages of the subject matter of the invention will become clear from the dependent claims and also from the following description of the drawings and the associated general production methods and specific examples.

[0222] In the drawings:

[0223] FIG. 1 shows the structure of an organic light-emitting diode;

[0224] FIG. 2 shows the structure of an organic solar cell with PIN structure, which converts light into electrical power;

[0225] FIG. 3 shows a possible cross-section of an organic field-effect transistor;

[0226] FIG. 4 shows a mononuclear zinc complex;

[0227] FIG. 5 shows a binuclear zinc complex with paddle wheel structure;

[0228] FIG. 6 shows a trinuclear zinc complex;

[0229] FIG. 7 shows a pentanuclear zinc complex comprising ethyl units;

[0230] FIG. 8 shows the current density against the voltage for the undoped matrix material (HTM014) and for the matrix material doped with Zn3;

[0231] FIG. 9 shows the current density against the voltage for the undoped matrix material (HTM014) and for the matrix material doped with Zn8;

[0232] FIG. 10 shows the current density against the voltage for the undoped matrix material (HTM014) and for the matrix material doped with Zn(3,5-tfmb);

[0233] FIG. 11 shows the current density against the voltage for the undoped matrix material (HTM014) and for the matrix material doped with Zn(tfa);

[0234] FIGS. 12A and 12B illustrate the broad usability and good p-dopant effect of zinc complexes according to for various matrix materials;

[0235] FIG. 13A shows the schematic structure of an embodiment of an organic electronic component designed as organic light-emitting diode;

[0236] FIG. 13B shows experimental data obtained by the organic light-emitting diodes of FIG. 13A; and

[0237] FIG. 14 shows the absorption spectrum of a layer doped with a zinc complex according to embodiments.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0238] FIG. 1 schematically shows the structure of an organic light-emitting diode (10). The light-emitting diode comprises or consists of the following layers: glass layer (1); transparent conductive oxide (TCO) or PEDOT:PPS or PANI layer (2); hole injection layer (3); hole transport layer (HTL) (4); emitting layer (EML) (5); hole blocking layer (HBL) (6); electron transport layer (ETL) (7); electron injection layer (8) and a cathode layer (9);

[0239] FIG. 2 schematically shows the structure of an organic solar cell with PIN structure (20), which converts light (21) into electrical power. The solar cell comprises or consists of a layer of indium tin oxide (22); a p-doped layer (23); an absorption layer (24); an n-doped layer (25) and a metal layer (26);

[0240] FIG. 3 schematically shows a possible cross-section of an organic field-effect transistor (30). There are applied to a substrate (31): a gate electrode (32), a gate dielectric (33), a source and drain contact (34+35) and an organic semiconductor (36). The hatched areas show the areas at which contact doping is helpful.

[0241] FIG. 4 schematically shows a mononuclear zinc complex, described by Zelenak et al. in “Preparation, characterisation and crystal structure of two zinc(II)benzoate complexes with pyridine-based ligands nicotinamide and methyl-3-pyridylcarbamate” Inorganica Chimica Acta 357 (2004) 2049-2059.

[0242] FIG. 5 schematically shows a binuclear zinc complex with paddle wheel structure, described by William Clegg et al. in “Zinc Carboxylate Complexes: Structural Characterisation of some Binuclear and Linear Trinuclear Complexes”, J. Chem. Soc. Dalton Trans. 1986, 1283. In addition to quinoline, the carboxylate of crotonic acid acts as ligand in particular.

[0243] FIG. 6 schematically shows a trinuclear zinc complex also described by William Clegg et al. in “Zinc Carboxylate Complexes: Structural Characterisation of some Binuclear and Linear Trinuclear Complexes”, J. Chem. Soc. Dalton Trans. 1986, 1283.

[0244] FIG. 7 schematically shows a pentanuclear zinc complex comprising ethyl units, described by Katherine L. Orchard et al. in “Pentanuclear Complexes for a Series of Alkylzinc Carboxylates”, Organometallics 2009, 28, 5828-5832. The high structural diversity is clear from the fact that the complex comprises alkyl ligands in addition to carboxylate ligands, said alkyl ligands not having been replaced completely by carboxylate ligands within the scope of the synthesis.

[0245] FIG. 8, for Example I, Zn3, schematically shows the current density against the voltage for the undoped matrix material (HTM014, Merck KGaA) and for the matrix material doped with Zn3. The co-evaporation of the zinc complex and of the matrix material is performed here in a temperature range of 169-182° C. The proportion of HTM014 in the obtained layer is 85 volume %. A very good dopant effect of the dopant is observed.

[0246] FIG. 9, for Example II, Zn8, schematically shows the current density against the voltage for the undoped matrix material (HTM014) and for the matrix material doped with Zn8. The co-evaporation of the zinc complex and of the matrix material is performed here in a temperature range of 230-231° C. The proportion of HTM014 in the obtained layer is 85 volume %. The good dopant properties are clearly evident from the graph. No outgassing is observed.

[0247] In Example II a much higher sublimation temperature is observed than in Example I. Thus, the compounds are not the same.

[0248] FIG. 10, for Example III, Zn(3,5), schematically shows the current density against the voltage for the undoped matrix material (HTM014) and for the matrix material doped with Zn(3,5-tfmb). The co-evaporation of the zinc complex and of the matrix material in the latter case is performed in a temperature range of 258-275° C. The proportion of HTM014 in the doped layer is 85 volume %. No doping effect is observed.

[0249] FIG. 11, for Example IV, Zn(tfa), schematically shows the current density against the voltage for the undoped matrix material (HTM014) and for the matrix material doped with Zn(tfa). The proportion of HTM014 in the doped layer is 85 volume %. A very good doping effect is observed.

[0250] FIG. 12A, for Example IV, Zn(tfa), schematically shows the current density against the voltage. Here, the commercially obtainable matrix material NHT49 from Novaled is doped with Zn(tfa). The current-voltage curve shows an excellent p-dopant effect of the zinc complexes according to the invention.

[0251] FIG. 12B, for Example IV, Zn(tfa), schematically shows the current density against the voltage. Here, the commercially obtainable matrix material HTM081 from Merck is doped with Zn(tfa). The current-voltage curve here as well shows an excellent p-dopant effect.

[0252] FIGS. 12A and 12B illustrate the broad usability and good p-dopant effect of zinc complexes according to the invention for various matrix materials. In addition, different p-dopant concentrations were tested in both cases. Measurements between 3 and 15 vol. % of the p-dopant in the entire p-doped layer are shown in the two graphs. The zinc complexes according to the invention can be used within a very wide range of concentrations in the doped layer. Particularly good values are attained between 1 and 25 vol. % of the zinc complex, wherein the range from 3 to 15 vol. % is more preferred. The latter range is shown in each of the figures. The best values are attained between 5 and 10 vol. % (inclusive) of the zinc complex, in relation to the p-doped organic region or the p-doped organic layer.

[0253] FIG. 13A shows the schematic structure of an embodiment of an organic electronic component according to the invention, designed as organic light-emitting diode. This is a test arrangement for determining the optoelectronic properties of components comprising a matrix having the zinc complexes according to the invention as p-dopant.

[0254] The OLED of FIG. 13A has an anode made of indium tin oxide (ITO) with a thickness of 130 nm. The anode is followed by the hole injection layer, which comprises the zinc complex to be tested as p-dopant. The hole injection layer has a layer thickness of 70 nm. By way of example, the matrix material NHT49 from Novaled was selected as hole conductor matrix of the hole injection layer. Tests for various p-dopant concentrations, specified in volume %, were performed. In addition to the components doped with the zinc complex to be tested, components were also produced which differ merely by the used p-dopant and concentration thereof. The commercially available p-dopant NDP9 from the company Novaled was used as reference p-dopant. The hole injection layer was followed lastly by the electron blocking layer (EBL for short). The emission layer (EML for short), the hole blocking layer (HBL for short), the electron injection layer (EIL for short) and lastly a cathode comprising or consisting of aluminum then follow as further layers of the OLED.

[0255] FIG. 13B shows the experimental data obtained by means of measurements on the organic light-emitting diodes presented in FIG. 13A. As comparative example, the widespread, commercially obtainable dopant NDP9 from the company Novaled was used. All further measurements were taken using zinc trifluoroacetate complexes, Zn(tfa), as p-dopant with volume concentrations between 3 and 15 vol. % in relation to the doped layer. In each case, the commercially obtainable hole conducting matrix material NHT49 from Novaled served as matrix material. The measurements were each taken at the same luminance, resulting in a comparable current density and operating voltage for the components doped with the Zn dopant and for the components doped with NDP9. The efficiency variables constituted by light yield (Peff), electricity yield (Ieff) and external quantum yield (EQE) are even higher in the components comprising the zinc complex according to the invention in the concentration range up to 10% with constant colour coordinates Cx and Cy than in the components comprising the reference dopant. The measurements in a conventionally structured test arrangement, corresponding to an organic light-emitting diode, thus confirm the excellent p-dopant effect of the zinc complex according to the invention and the suitability for its use for doping hole conducting matrix materials in organic electronic components. Lastly, the measurements indicate that OLEDs comprising the zinc complexes according to the invention permit improved light yields, electricity yields, and external quantum yields. This can be attributed at least partially to the only very low absorption of layers doped with the zinc complexes. Losses by absorption by the dopant in the component are thus reduced, which has a positive effect particularly in the case of organic electronic components in the field of optoelectronics, such as OLEDs.

[0256] FIG. 14 shows the absorption spectrum of a layer doped with a zinc complex according to the invention. FIG. 14A compares the absorption spectrum of quartz, which has an excellent light transmittance, with the absorption behavior of a doped layer of HTM014 200 nm thick, doped with 5% zinc trifluoroacetate. The measurements were taken using a conventional dual beam spectrophotometer. In the range of visible light, i.e., between 400 and 700 nm, the doped layer demonstrates surprisingly low values for the absorbance, which is a measure for absorption. FIG. 14B shows the section between 450 and 800 nm enlarged. Here, it can be seen that in the visible range the absorbance of the doped layer is even less than 0.03, and over wide areas is even less than 0.02. Such a low absorption is achieved only for few materials and shows that the zinc complexes according to the invention are outstandingly suited for optoelectronic devices, such as organic light-emitting diodes or organic solar cells.

[0257] The zinc complexes of the organic electrical component according to the invention can be obtained, for example, by reacting di-alkyl zinc or di-aryl zinc with the corresponding carboxylic acids or derivatives thereof. The substitution of the alkyl or aryl ligands of the starting complex of zinc was performed here in a number of steps, wherein the substitution can also be incomplete. This is presented hereinafter in an exemplary manner for a two-stage reaction, which, for example, can also be stopped after the first stage:

##STR00014##

Explanation of the Terms:

[0258] LC corresponds here to the previously described ligand L.sup.C and is an alkyl or aryl. L.sup.C* independently of L.sup.C is also an alkyl or aryl, wherein L.sup.C and L.sup.C* can be the same or different. R.sup.3, for the specified exemplary production method, corresponds to the group R.sup.3 of the ligand L of the zinc complex according to the invention. The carboxylate comprising R.sup.3 consequently corresponds in this example to the ligand L of the finished zinc complex (i.e., L=R.sup.3COO—).

[0259] It is additionally possible to obtain the mixed aryl/alkyl carboxylates by means of comproportionation:

##STR00015##

[0260] If the substituents L.sup.C are also fluorinated, a class of mixed alkyl/aryl zinc dopants is obtained. The doping strength, volatility and solubility thus can be adjusted not only by the carboxylate ligand R.sup.3COO—, but additionally also by the ligand L.sup.C largely independently of the sublimation temperature.

[0261] Oligomer structures or clusters are also accessible by the same procedure as the synthesis presented formally here.

EXAMPLE I

[0262] Example I relates to a zinc pentafluorobenzoate complex, Zn(pfb), abbreviated hereinafter to Zn3, which was obtained via the synthetic pathway described hereinafter:

[0263] 30.59 mmol of pentafluorobenzoic acid were dissolved in 80 ml of toluene and cooled to 0° C. 15.29 mmol of diethylzinc solution (15% in toluene) were diluted with 20 mL of toluene, also cooled, and added carefully dropwise under protective gas to the pentafluorobenzoic acid solution. Under stirring, the solution was brought to room temperature. After approximately one hour, a small amount of white precipitate had already formed. The mixture was then stirred for 15 hours at a bath temperature of 50° C. A dense, white precipitate was obtained. The solvent was reduced to a third, and the white product was suctioned off via a P4 frit and was washed three times with cyclohexane and dried in a vacuum. The yield was: 6.11 g (82%); sublimation range: 215-230° C./10.sup.−5 mbar.

[0264] A matrix layer with p-dopant as measured in FIG. 8, for Example I, was obtained by means of co-evaporation of the matrix material and also of the zinc complex. The hole transport layer was thus attained directly from the gas phase by reaction of the components on the substrate.

[0265] Here, the layers to be measured were produced as follows

[0266] Evaporation

[0267] ITO-pre-structured glass substrates were subjected for 10 minutes to an oxygen plasma treatment and were then transferred as quickly as possible into the evaporator. The evaporator was transferred into an argon glovebox, in which the oxygen and water concentration was less than 2 ppm.

[0268] All evaporations were performed in a vacuum of less than 2×10.sup.−6 mbar basic pressure (the pressure then rose with the evaporation)).

[0269] Both matrix material and dopant material were first heated to just below the evaporation point, then were heated until constant evaporation could be observed.

[0270] The total evaporation rate was approximately 1 Å/s, wherein the evaporation rate of the doping material was set via the evaporation rate of the matrix material.

[0271] Once the shutters were closed, the glovebox was cooled to 40° C., flooded with argon, and the mask for the deposition of the cathode was changed, and the glovebox was evacuated again.

[0272] The electrode consisted of a layer of aluminum 150 nm thick, which was applied with an initial evaporation rate of 0.5 Å/s, which was increased slowly to 5 Å/s.

[0273] The same process was also applied in the following examples (Examples II to IV).

[0274] FIGS. 9 to 11 relate to doped and undoped HTM-014 (matrix material, Merck KGaA). Here, layers of undoped HTM-014 (Merck KGaA) were produced on the one hand, and on the other hand HTM-014 doped with 15% of the particular zinc complex were produced, said layers being 200 nm thick in each case.

EXAMPLE II

[0275] Example II also relates to the production of a second zinc pentafluorobenzoate complex Zn(pfb) different from Example I, abbreviated to Zn8. 30.59 mmol of pentafluorobenzoic acid were cooled in 60 ml of diethyl ether to 0° C. 15.29 mmol of diethyl zinc solution (1.0 M in hexane) were diluted with 20 ml diethyl ether, also cooled, and were carefully added dropwise under protective gas to the pentafluorobenzoic acid solution. Under stirring, the solution was brought to room temperature. The solution was then stirred for 15 hours at a bath temperature of 30° C. A white precipitate was obtained. The white product was suctioned off via a P4 frit and was washed three times with cyclohexane and dried in a vacuum. The yield was: 5.6 g (75%); sublimation range: 255-270° C./10.sup.−5 mbar.

[0276] The substance obtained by the synthesis procedure presented in Example II surprisingly has a much higher sublimation temperature than the compound as obtained by the method presented in Example I, and it therefore can be assumed that this substance is a complex compound different from the substance obtained in Example I.

EXAMPLE III

[0277] Example III relates to the production of a zinc complex with 3,5-bis(trifluoromethyl)benzoate ligand, Zn(3,5-tfmb), also abbreviated to Zn(3,5).

[0278] For this purpose, 30.59 mmol of 3,5-(trifluoromethyl)benzoic acid were dissolved in a mixture of 50 ml of toluene and 30 ml of benzene and were cooled to 0° C. 15.29 mmol of diethylzinc solution (15% toluene) diluted with 10 ml toluene, which was also cooled, were added dropwise under protective gas. A jelly-like mass was obtained, which was stirred for 18 hours at a bath temperature of 90° C. A slightly cloudy solution was then produced. The solvent was removed completely under vacuum, leaving a white powder. Yield: 8.39 g (86%); sublimation range: 260-280° C./10.sup.−5 mbar.

EXAMPLE IV

[0279] Example IV relates to the production of a zinc complex with trifluoroacetate ligand, abbreviated to Zn(tfa).

[0280] 48.16 mmol of trifluoroacetic acid were mixed with 60 mmol benzene and cooled to 10° C. 22.9 mmol of diethylzinc solution (15% in toluene), diluted with 60 ml of benzene, were then added carefully dropwise. The mixture was stirred for 15 hours at room temperature to produce a white precipitate. A third of the solvent was removed, and the white product was suctioned off via a P4 frit and was washed three times with cyclohexane. The yield was: 5.55 g (83%); sublimation range 163-173° C./10.sup.−5 mbar.

[0281] The individual combinations of the constituents and the features of the above-mentioned embodiments are exemplary; the exchange and substitution of these teachings with other teachings contained in this document with the cited documents is also expressly considered. A person skilled in the art will know that variations, modifications, and other embodiments described here can also be provided, without departing from the inventive concept or the scope of the invention.

[0282] Accordingly, the above description is exemplary and should not be considered to be limiting. The word “comprise” as used in the claims does not rule out other constituents or steps. The indefinite article “a” does not rule out the meaning of a plural. The mere fact that specific measures are recited in claims different from each other does not mean that a combination of these measures cannot be used to an advantage. The scope of the invention is defined in the following claims and the associated equivalents.