TRANSITION METAL COMPLEXES COMPRISING CARBENE LIGANDS SERVING AS EMITTERS FOR ORGANIC LIGHT-EMITTING DIODES (OLED'S)

Abstract

Use of transition metal complexes of the formula (I) in organic light-emitting diodes

##STR00001## where: M.sup.1 is a metal atom; carbene is a carbene ligand; L is a monoanionic or dianionic ligand; K is an uncharged monodentate or bidentate ligand selected from the group consisting of phosphines; CO; pyridines; nitriles and conjugated dienes which form a π complex with M.sup.1; n is the number of carbene ligands and is at least 1; m is the number of ligands L, where m can be 0 or ≥1; is the number of ligands K, where o can be 0 or ≥1; where the sum n+m+o is dependent on the oxidation state and coordination number of the metal atom and on the denticity of the ligands carbene, L and K and also on the charge on the ligands carbene and L, with the proviso that n is at least 1, and also
an OLED comprising these transition metal complexes, a light-emitting layer comprising these transition metal complexes, OLEDs comprising this light-emitting layer, devices comprising an OLED according to the present invention, and specific transition metal complexes comprising at least two carbene ligands.

Claims

1.-18. (canceled)

19. An uncharged transition metal complex comprising a structure of the formula (II) ##STR00046## wherein the symbols have the following meanings: Do.sup.1 is a donor atom selected from the group consisting of C, P, N, O and S; Do.sup.2 is a donor atom selected from the group consisting of C, N, P, O and S; r is 2 when Do.sup.1 is C, is 1 when Do.sup.1 is N or P and is 0 when Do.sup.1 is O or S; s is 2 when Do.sup.2 is C, is 1 when Do.sup.2 is N or P and is 0 when Do.sup.2 is O or S; X is a spacer selected from the group consisting of silylene, alkylene, arylene, heteroarylene and alkenylene; p is 0 or 1; q is 0 or 1; Y.sup.1, Y.sup.2 are each, independently of one another, hydrogen or a carbon-containing group selected from the group consisting of alkyl, aryl, heteroaryl and alkenyl groups, or Y.sup.1 and Y.sup.2 together form a bridge between the donor atom Do.sup.1 and the nitrogen atom N which has at least two atoms of which at least one is a carbon atom; Y.sup.3 is hydrogen or an alkyl, aryl, heteroaryl or alkenyl radical, or ##STR00047## wherein Do.sup.2′, q′, s′, R.sup.3′, R.sup.1′, R.sup.2′, X′ and p′ are each, independently of one another, as defined for Do.sup.2, q, s, R.sup.3, R.sup.1, R.sup.2, X and p; R.sup.1, R.sup.2 are each, independently of one another, hydrogen or an alkyl, aryl, heteroaryl or alkenyl radical, or R.sup.1 and R.sup.2 together form a bridge having a total of from three to five atoms of which one or two atoms may be heteroatoms and the remaining atoms are carbon atoms, so that the group ##STR00048## forms a five- to seven-membered, ring which, if appropriate, may contain, in addition to the existing double bond, one further double bond or in the case of a six- or seven-membered ring two further double bonds and may optionally be substituted by alkyl or aryl groups and may, if appropriate, comprise at least one heteroatom; and R.sup.3 is hydrogen or an alkyl, aryl, heteroaryl or alkenyl radical.

20. The uncharged transition metal complex as claimed in claim 19, wherein the group ##STR00049## is selected from the group consisting of ##STR00050## wherein the symbols have the following meanings: R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9 and R.sup.11 are each hydrogen, alkyl, aryl, heteroaryl or alkenyl or a substituent which acts as a donor or acceptor; R.sup.10 is alkyl, aryl, heteroaryl or alkenyl or 2 radicals R.sup.1° together form a fused-on ring, or R.sup.10 is a radical which acts as a donor or acceptor; v is from 0 to 4 and when v is 0 the four carbon atoms of the aryl radical in the formula c which are optionally substituted by R.sup.10 bear hydrogen atoms; and Y.sup.3 is a hydrogen atom or an alkyl, aryl, heteroaryl or alkenyl radical, or ##STR00051## wherein Do.sup.2′, q′, s′, R.sup.3′, R.sup.1′, R.sup.2′, X′ and p′ are defined, independently of one another, as for Do.sup.2, q, s, R.sup.3, R.sup.1, R.sup.2, X and p.

21. The uncharged transition metal complex as claimed in claim 19, wherein the group ##STR00052## denotes the structure ##STR00053## wherein the symbols have the following meanings: Z is CH or N and can be located in the o, m or p position relative to the point of linkage to the group ##STR00054## R.sup.12 is an alkyl, aryl, heteroaryl or alkenyl radical, or 2 radicals R.sup.12 together form a fused-on ring which may, if appropriate, comprise one or more heteroatoms, or R.sup.12 is a radical which acts as a donor or acceptor; and t is 0 to 3 and when t>1 the radicals R.sup.12 can be identical or different.

22. The uncharged transition metal complex as claimed in claim 19, wherein the structure of formula (II) is selected from the group consisting of ##STR00055## wherein the symbols have the following meanings: Z, Z′ are identical or different and are each CH or N; R.sup.12, R.sup.12′ are identical or different and are each an alkyl, aryl, heteroaryl or alkenyl radical, or 2 radicals R.sup.12 or R.sup.12′ together form a fused-on ring which may, if appropriate, comprise at least one heteroatom, or R.sup.12 or R.sup.12′ is a radical which acts as a donor or acceptor; t and t′ are identical or different and are each from 0 to 3, and when t or t′>1 the radicals R.sup.12 or R.sup.12′ can be identical or different; R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9 and R.sup.11 are each hydrogen, alkyl, aryl, heteroaryl or alkenyl or a radical which acts as a donor or acceptor; R.sup.10 is alkyl, aryl, heteroaryl or alkenyl or 2 radicals R.sup.1° together form a fused-on ring which may, if appropriate, comprise at least one heteroatom, or R.sup.10 is a radical which acts as a donor or acceptor; and v is from 0 to 4 and when v is 0 the four carbon atoms of the aryl radical in the formula c which are optionally substituted by R.sup.10 bear hydrogen atoms.

23. An organic light-emitting diode comprising at least one transition metal complex according to claim 19.

24. A light-emitting layer comprising at least one transition metal complex according to claim 19.

25. An organic light-emitting diode comprising a light-emitting layer according to claim 24.

26. A device selected from the group consisting of stationary visual display units of computers, televisions, visual display units in printers, kitchen appliances and advertising signs, lighting units, and information signs; and mobile visual display units in mobile telephones, laptops, vehicles and destination displays in buses and trains, comprising an organic light-emitting diode as claimed in claim 23.

27. A method of coloring a polymeric material comprising adding an uncharged transition metal complex as claimed in claim 19 to said polymeric material.

28. The uncharged transition metal complex as claimed in claim 19, wherein the structure of formula (II) is coordinated to a Pt(II) metal atom having a coordination number of 4.

29. An uncharged transition metal complex of the formula (I) ##STR00056## wherein the symbols have the following meanings: WV is Pt(II) having a coordination number of 4; carbene is a carbene ligand; L is a monoanionic or dianionic ligand, which may be monodentate or bidentate; K is an uncharged monodentate or bidentate ligand selected from the group consisting of phosphines; phosphonates and derivatives thereof, arsenates and derivatives thereof; phosphites; CO; pyridines; nitriles and conjugated dienes which form a π complex with M.sup.1; n is the number of carbene ligands, wherein n is 1; m is the number of ligands L, wherein m is 0; and o is the number of ligands K, wherein o is 0.

30. An organic light-emitting diode comprising at least one transition metal complex according to claim 29.

31. A light-emitting layer comprising at least one transition metal complex according to claim 29.

32. An organic light-emitting diode comprising a light-emitting layer according to claim 31.

33. A device selected from the group consisting of stationary visual display units of computers, televisions, visual display units in printers, kitchen appliances and advertising signs, lighting units, and information signs; and mobile visual display units in mobile telephones, laptops, vehicles and destination displays in buses and trains, comprising an organic light-emitting diode as claimed in claim 30.

34. A method of coloring a polymeric material comprising adding an uncharged transition metal complex as claimed in claim 29 to a polymeric material.

35. An uncharged transition metal complex of formula (I) ##STR00057## wherein the symbols have the following meanings: M.sup.1 is a metal atom selected from the group consisting of Co, Rh, Ir, Nb, Pd, Pt, Fe, Ru, Os, Cr, Mo, W, Mn, Tc, Re, Cu, Ag and Au in any oxidation state possible for the respective metal atom; L is a monoanionic or dianionic ligand; K is an uncharged monodentate or bidentate ligand selected from the group consisting of phosphines; phosphonates and derivatives thereof, arsenates and derivatives thereof, phosphites, CO; pyridines which may be substituted by alkyl or aryl groups; nitriles and dienes which form a π complex with M.sup.1; n is the number of carbene ligands, where n is at least 1 and when n>1 the carbene ligands in the complex of the formula I can be identical or different; m is the number of ligands L, where m can be 0 or ≥1 and when m>1 the ligands L can be identical or different; o is the number of ligands K, where o can be 0 or ≥1 and when o>1 the ligands K can be identical or different; wherein at least one carbene in the complex of formula (I) comprises formula (II) ##STR00058## wherein the symbols have the following meanings: Do.sup.1 is N; Do.sup.2 is a donor atom selected from the group consisting of C, N, P, O and S; r is 1; s is 2 when Do.sup.2 is C, is 1 when Do.sup.2 is N or P and is 0 when Do.sup.2 is O or S; X is a spacer selected from the group consisting of silylene, alkylene, arylene, heteroarylene and alkenylene; p is 0; q is 0; Y.sup.1 and Y.sup.2 together form an unsaturated bridge between Do.sup.1 and the nitrogen atom N which has at least two atoms of which at least one is a carbon atom; Y.sup.3 is ##STR00059## Z′ is CH or N; R.sup.12′ is an alkyl, aryl, heteroaryl or alkenyl radical, or 2 radicals R.sup.12′ together form a fused-on ring which may, if appropriate, comprise one or more heteroatoms, or R.sup.12′ is a radical which acts as a donor or acceptor; t′ is 0 to 3 and when t>1 the radicals R.sup.12 can be identical or different; R.sup.1 and R.sup.2 together form a bridge having a total of from three to five atoms of which one or two atoms may be heteroatoms and the remaining atoms are carbon atoms, so that the group ##STR00060## forms a five- to seven-membered, ring which, if appropriate, may contain, in addition to the existing double bond, one further double bond or in the case of a six- or seven-membered ring two further double bonds and may optionally be substituted by alkyl or aryl groups and may, if appropriate, comprise at least one heteroatom; and R.sup.3 is hydrogen or an alkyl, aryl, heteroaryl or alkenyl radical.

36. An organic light-emitting diode comprising at least uncharged transition metal complex according to claim 35.

37. A light-emitting layer comprising at least one uncharged transition metal complex according to claim 35.

38. A device selected from the group consisting of stationary visual display units of computers, televisions, visual display units in printers, kitchen appliances, advertising signs, lighting units, information signs; mobile visual display units in mobile telephones, laptops, vehicles, and destination displays in buses and trains, comprising the organic light-emitting diode of claim 36.

Description

EXAMPLES

[0292] 1. Preparation of the Ligands:

[0293] The necessary ligand precursors were prepared by methods based on literature methods:

[0294] a) Compound (1)

##STR00037##

[0295] The synthesis is carried out starting from N,N-diphenylethane-1,2-diamine using a method based on that described in Organic Letters, 1999, 1, 953-956; Angewandte Chemie, 2000, 112, 1672-1674. The bisamine is reacted with triethyl formate in the presence of ammonium tetrafluoroborate.

[0296] The compound was obtained after recrystallization from ethanol.

[0297] .sup.1H-NMR (400 MHz, DMSO):

[0298] δ=4.60 (s, 4H, CH.sub.2), 7.40 (tt, 2H), 7.57 (dd, 4H), 7.65 (dd, 4H), 9.95 (s, 1H, C.sup.+H)

[0299] .sup.13C-NMR (100 MHz, DMSO):

[0300] δ=48.2, 118.4, 127.0, 129.6, 136.0, 151.7

[0301] b) Compound (2)

##STR00038##

[0302] The synthesis starts, using a method based on that described in Chem. Ber. 1971, 104, 92-109 (in particular page 106), with the preparation of the bisimine of glyoxal and aniline or para-toluidine.

[0303] The Schiff bases obtained are converted into the corresponding imidazolium chloride salt by treatment with a hydrochloric acid suspension of paraformaldehyde in dioxane using the method described in Journal of Organometallic Chemistry 2002, 606, 49-54.

[0304] Using Aniline:

[0305] δ=7.64 (t, 2H), 7.72 (t, 4H), 7.93 (d, 4H), 8.60 (d, 2H), 10.75 (s, 1H) MS (ESI, ACN/H.sub.2O 8/2):

[0306] m/e=221.0

[0307] Using Para-Toluidine:

[0308] .sup.1H-NMR (500 MHz, DMSO):

[0309] δ=2.42 (s, 6H), 7.49 (d, 4H), 7.88 (d, 4H), 8.61 (d, 2H), 10.52 (t, 1H)

[0310] The anion can be replaced by treatment with AgBF.sub.4 or NaBF.sub.4.

[0311] c) Compound (3)

##STR00039##

[0312] The synthesis starts out from 1,2-phenylenediamine. After introduction of acetyl groups on the amino functions, the phenyl groups were introduced into the resulting amide with the aid of a copper-catalyzed procedure as described in Synthetic Communications, 2000, 30, 3651-3668. Without purification, the material was treated in boiling ethanolic KOH solution. The product was obtained by chromatography.

[0313] .sup.1H-NMR (CD.sub.2Cl.sub.2, 500 MHz):

[0314] δ=5.70 (s, broad, 2H), 6.87 (t, 2H), 6.93 (d, 4H), 6.97 (dd, 2H), 7.22 (t, 4H), 7.28 (dd, 2H)

[0315] The imidazolium salt required was prepared by treatment of N,N′-diphenylbenzene-1,2-diamine with triethyl orthoformate in the presence of ammonium tetrafluoroborate. The material was obtained by crystallization.

[0316] .sup.1H-NMR (DMSO, 400 MHz):

[0317] δ=7.74-7.84 (m, 8H), 7.91-7.98 (m, 6H), 10.57 (s, 1H)

[0318] d) Compound (4)

[0319] Da) Preparation of Compound 4a

##STR00040##

[0320] In a countercurrent of argon, 3.16 g (20 mmol) of 2,3-diaminonaphthalene (Acros) and 6.28 g (40 mmol) of distilled bromobenzene (Aldrich) together with 80 ml of toluene (water-free) were placed in a flask which had been flushed with argon. The brown suspension was degassed by application of a vacuum to the flask. Argon was then admitted again and a spatula tip of Pd.sub.2(dba).sub.3, a spatula tip of 9,9-dimethyl-4,5-bis-(diphenylphosphino)xanthene (xantphos), 2.70 g (28 mmol) of sodium tert-butoxide and 0.36 g (20 mmol) of degassed water were added in a countercurrent of argon. The brown suspension was heated to reflux and stirred under reflux for 15 hours. It was then allowed to come to room temperature.

[0321] For the work-up, the mixture was diluted with methylene chloride and extracted twice with water, then dried over sodium sulfate, filtered and the filtrate was evaporated under reduced pressure. The residue was purified by column chromatography (silica gel, methylene chloride comprising 5 ml of triethylamine per l of methylene chloride). The fractions comprising the product were combined and freed of the solvent under reduced pressure. This gave 2.7 g (43.5%) of compound (4a).

[0322] .sup.1H-NMR (CDCl.sub.3, 400 MHz):

[0323] δ=5.85 (s, broad, NH), 6.97 (tt, 2H, J=7.3 Hz, J=1.2 Hz), 7.07 (dd, 4H, J=8.7 Hz, J=1.1 Hz), 7.28-7.32 (m, 6H), 7.60 (dd, 2H, J=6.1 Hz, J=3.1 Hz), 7.64 (s, 2H)

[0324] MS (EI):

[0325] m/e=310.0, 311.0, 312.0 (M.sup.+)

[0326] db) Preparation of Compound (4)

##STR00041##

[0327] A two-neck flask was flushed with nitrogen for 20 minutes. 7.68 g (24.74 mmol) of the 2,3-di-N-phenylaminonaphthalene were then dissolved in 51.34 g (346.4 mmol) of triethyl formate at 100° C. and 2.59 g (24.74 mmol) of ammonium tetrafluoroborate were added, also under a countercurrent of nitrogen. The solution was then heated to reflux and stirred under reflux for 12 hours. The reaction mixture was then brought to room temperature.

[0328] For the work-up, the reaction mixture was filtered through a G4 frit and the solid was washed with ortho ester. It was then dried at 50° C. in a vacuum drying oven. The material obtained in this way (6.05 g) was dissolved in methylene chloride and filtered by means of a suction filter. The mother liquor was evaporated under reduced pressure and the solid was once again dried at 50° C. in a vacuum drying oven. This gave 5.37 g (53%) of the compound (4).

[0329] .sup.1H-NMR (0114600902, 400 MHz, CD.sub.2C.sub.2):

[0330] δ=7.69 (dd, 2H, J 2.9 Hz, J=6.7 Hz), 7.76-7.82 (m, 6H), 7.91-7.95 (m, 4H), 8.10 (dd, 2H, J=3.3 Hz, J=6.6 Hz), 8.29 (s, somewhat broader, 2H), 9.75 (s, 1H)

[0331] Elemental Analysis:

[0332] Exp. 18.3% F 67.2% C 6.8% N 4.10% H

[0333] Theor. 18.6% F 67.6% C 6.8% N 4.16% H

[0334] 2. Preparation of the Metal Complexes:

[0335] Ir(imidazolidine).sub.3 was prepared by a method based on that of P. B. Hitchcock, M. F. Lapped, P. Terreros, J. Organomet. Chem. 1982, 239, 026-030. Unlike the literature method cited, the imidazolidinium salt rather than the Wanzlick olefin was used as starting material.

[0336] Preparation of the metal-carbene complexes (all syntheses described were carried out in pure solvents under an inert gas atmosphere by means of the Schlenk technique):

[0337] a) Preparation of an Ir Complex (5)

##STR00042##

[0338] In a 100 ml three-necked flask, 3.0 g (9.6 mmol) of the imidazolium salt (compound (1)) were suspended in 40 ml of tetrahydrofuran. The light-brown suspension was admixed at room temperature with a solution of 1.11 g (9.7 mmol) of KOBu in 10 ml of THF. The mixture was stirred at room temperature for one hour and subsequently evaporated to dryness. After the solid had been taken up again in 30 ml of toluene, the resulting suspension was added to a solution of 820 mg (1.2 mmol) of [(μ-Cl)(η.sup.4-1,5-cod)Ir].sub.2 in 20 ml of toluene. The reaction mixture was refluxed for 2 hours, stirred overnight at room temperature and subsequently refluxed for another 3.5 hours. It was then allowed to cool to room temperature. The precipitate was filtered off, washed with toluene, extracted with methylene chloride and the methylene chloride was removed under reduced pressure. The residue was subjected to purification by column chromatography. This gave a light-yellow powder (240 mg, 15%).

[0339] .sup.13C-NMR (CD.sub.2Cl.sub.2, 125 MHz): 200.0 (NCN), 149.3, 146.5, 142.5 (each C.sub.q or IrC.sub.phenyl), 134.5, 127.2, 126.5, 125.5, 120.6, 119.7, 106.8 (each CH.sub.phenyl), 53.8, 44.1 (NCH.sub.2CH.sub.2N).

[0340] Mass (EI): m/e=856.

[0341] Optical spectroscopy: 2=533 nm (main maximum of the powder).

[0342] b) Preparation of an Ir Complex (6)

##STR00043##

[0343] In a 100 ml three-necked flask, 0.92 g (2.7 mmol) of the imidazolium salt (compound (2)) was dissolved in 20 ml of tetrahydrofuran. At −8° C., 547 ml of base (0.5 M in toluene, 2.8 mmol) were added over a period of 10 minutes and the mixture was stirred at room temperature for 1 hour.

[0344] 310 mg (0.460 mmol) of [(μ-Cl)(η.sup.4-1,5-cod)Ir].sub.2 were dissolved in 20 ml of THF, cooled to −78° C. and the salt mixture was added dropwise to this solution. The mixture was stirred for 2 hours at 60° C., overnight at room temperature, for 8 hours under reflux and subsequently overnight at room temperature. After filtration, the solution was evaporated to dryness and the brown residue was subjected to purification by column chromatography. This gave a white powder (170 mg, 20%).

[0345] .sup.1H-NMR (CD.sub.2Cl.sub.2, 500 MHz): 7.23 (1H, CH.sub.phenyl or NCHCHN), 7.02 (1H), 6.79 (2H), 6.68 (1H), 6.30 (2H), 5.85 (2H) (each CH.sub.phenyl, or NCHCHN), 2.21 (3H, CH.sub.3), 2.01 (3H, CH.sub.3). .sup.13C-NMR (CD.sub.2Cl.sub.2, 125 MHz): 174.8 (NCN), 149.3, 144.2, 137.6, 135.7, 132.3 (each C.sub.q or IrC.sub.phenyl), 139.6, 127.8, 125.0, 120.2, 120.0, 113.4, 109.1 (CH.sub.phenyl or NCHCHN), 20.5, 19.9 (each CH.sub.3).

[0346] Mass (EI): m/e=934.

[0347] Optical spectroscopy: λ=489 nm (main maximum of the powder).

[0348] c) Preparation of an Ir Complex (7)

[0349] Synthesis Variant

##STR00044##

[0350] In a 100 ml three-necked flask, 0.99 g (2.8 mmol) of the benzimidazolium salt (compound (3)) was suspended in 20 ml of THF. A solution of 0.32 g of KOBu in 10 ml of THF was added to this light yellow suspension at room temperature. The mixture was stirred at room temperature for 45 minutes and subsequently evaporated to dryness. After the residue had been taken up again in 25 ml of toluene, this suspension was added to a solution of 310 mg of [(μ-Cl)(η.sup.4-1,5-cod)Ir].sub.2 (0.46 mmol) in 30 ml of toluene. The mixture was subsequently stirred for 15 minutes at room temperature, overnight at 80° C., for 8 hours under reflux, over the weekend at room temperature and for 5 hours under reflux. After cooling, the precipitate was separated off and the filtrate was evaporated. The yellow powder obtained was subjected to purification by column chromatography. This gave a white powder (410 mg, 43%)

[0351] Synthesis Variant II

[0352] 1.32 g (3.7 mmol) of the benzimidazolium salt (compound (3)) together with 25 ml of toluene were placed in a 100 ml three-neck flask. 7.5 ml of potassium bistrimethyl-silylamide (0.5 M in toluene, 3.7 mmol) were added at room temperature over a period of 30 minutes and the mixture was stirred at room temperature for 30 minutes. 310 mg (0.46 mmol) of [(μ-Cl)(η.sup.4-1,5-cod)Ir].sub.2 were dissolved in 30 ml of toluene and the salt mixture was added dropwise at room temperature. The mixture was stirred at room temperature for one hour, then at 70° C. for two hours and subsequently overnight under reflux. After filtration, the solution was evaporated to dryness and the brown residue was subjected to purification by column chromatography. This gave a white powder (0.75 g, 82%).

[0353] The Ir complex (7) is formed as a mixture of the kinetically preferred meridional (mer) isomer and the thermodynamically preferred facial (fac) isomer.

[0354] .sup.1H-NMR (fac/mer isomer mixture, data for the main isomer (fac isomer), CDCl.sub.3, 500 MHz): 8.03 (d, 1H), 7.85 (d, 1H), 7.21 (m, 2H), 7.01 (m, 1H), 6.93 (m, 1H), 6.65 (m, 111), 6.61 (m, 1H), 6.53 (m, 1H), 6.47 (m, 1H), 6.35 (d, 1H), 6.20 (m, 1H), 6.11 (m, 1H) each (CH.sub.aryl or NCHCHN).

[0355] .sup.13C-NMR (fac/mer isomer mixture, data for the main isomer (fac isomer), CDCl.sub.3, MHz): 187.8 (NCN), 148.8, 147.8, 137.2, 136.9, 131.7 (each C.sub.q or IrC.sub.phenyl), 135.9, 127.8, 127.3, 127.0, 126.6, 126.4, 123.6, 121.9, 120.8, 120.3, 111.6, 109.9, 109.5 (CH.sub.aryl).

[0356] Mass (fac/mer isomer mixture, EI): m/e=1000.0.

[0357] Elemental analysis (fac/mer isomer mixture, IrC.sub.54H.sub.39N.sub.6 ¾CH.sub.2Cl.sub.2): C, 65.2%; H, 3.8%; N, 7.9%; Cl, 5.0; found: C, 64.8%; H, 4.0%; N, 8.1%; Cl, 4.9%.

[0358] Optical spectroscopy: λ=467 nm (fac/mer isomer mixture, main maximum of the powder)

[0359] DTA (fac/mer isomer mixture): Rapid decomposition occurred at about 350° C. when the measurement was carried out in air. Decomposition of the sample commences at about 380° C. under inert gas. (Measurement conditions: in air: 28.0/5.0 (K/min)/750.0, under inert gas: 30.0/5.00 (K/min)/710).

[0360] d) Chromatography, Separation of the Fac and Mer Isomers of the Ir Complex of the Formula (7)

[0361] The TLC (eluent: toluene) shows 2 spots, with the fac isomer running at R.sub.F=0.5 and the mer isomer running at about R.sub.F=0.35.

[0362] 0.46 g of the material to be separated were dissolved in toluene with addition of a small amount of CH.sub.2Cl.sub.1-2 and heating to about 30-40° C.

[0363] The two isomers were subsequently separated chromatographically with small fractionation on silica gel (0.063-0.200 mm J. T. Baker) using toluene as eluent (dimensions of the column: length: 30 cm, diameter: 6 cm).

[0364] Amount of fac isomer obtained: 0.2886 g

[0365] .sup.1H-NMR (CD.sub.2Cl.sub.2, 500 MHz) (fac):

[0366] δ=8.10 (d, 3H), 7.94 (d, 3H), 7.28 (m, 6H), 7.06 (m, 3H), 7.02 (m, 3H), 6.74 (m, 3H), 6.68 (m, 3H), 6.60 (d, 3H), 6.56 (d, 3H), 6.42 (d, 3H), 6.29 (m, 3H), 6.18 (d, 3H).

[0367] mer isomer: 0.0364 g

[0368] .sup.1H-NMR (CD.sub.2Cl.sub.2, 500 MHz, −20° C.) (mer):

[0369] δ=8.30 (d, 1H), 7.89 (m, 2H), 7.73 (d, 1H), 7.56 (d, 1H), 7.31 (d, 1H), 7.28-7.16 (m, 5H), 7.08-7.01 (m, 3H), 6.98 (m, 1H), 6.93 (m, 1H), 6.85-6.20 (m, 21H), 5.78 (d, 1H), 5.64 (d, 1H).

[0370] e) Preparation of an Ir Complex (8)

##STR00045##

[0371] 1.51 g (3.7 mmol) of the naphthimidazolium salt together with 40 ml of toluene were placed in a 100 ml three-neck flask. 7.4 ml of potassium bis(trimethylsilyl)amide (0.5 M in toluene, 3.7 mmol) were added at RT over a period of 30 minutes and the mixture was stirred at room temperature for 30 minutes. 310 mg (0.46 mmol) of [(μ-Cl)(η.sup.4-1,5-cod)Ir].sub.2 were dissolved in 30 ml of toluene and the salt mixture was added dropwise at room temperature. The mixture was stirred at room temperature for one hour, then at 70° C. for two hours and then overnight under reflux. The mixture was evaporated to dryness and the brown residue was subjected to purification by column chromatography. This gave a light yellow powder (0.37 g, 35%).

[0372] .sup.1H-NMR (fac/mer isomer mixture, data for the main isomer (fac isomer)): (CD.sub.2Cl.sub.2, 500 MHz): δ=8.47 (s, 1H), 8.05 (m, 2H), 7.57 (d, 1H), 7.41 (m, 1H), 7.33 (d, 1H), 7.28 (t, 1H), 7.09 (m, 1H), 6.75 (s, 1H), 6.69 (d, 1H), 6.64 (t, 1H) 6.57 (d, 1H), 6.52 (m, 1H), 6.24 (m, 2H).

[0373] .sup.13C-NMR (fac/mer isomer mixture, data for the main isomer (fac isomer)): (CD.sub.2Cl.sub.2, 125 MHz): δ=193.9 (NCN), 146.67, 137.6, 136.9, 131.4, 129.5, 128.4 (C), 135.7, 128.2, 127.5, 127.4, 127.3, 127.0, 126.8, 126.7, 124.2, 124.0, 123.7, 120.7, 111.8, 106.2, 105.4 (CH).

[0374] Mass (EI): m/e=1151 (M-H.sup.+).

[0375] Elemental analysis (fac/mer isomer mixture, IrC.sub.69H.sub.45N.sub.6 ½CH.sub.2Cl.sub.2): C, 70.0%; H, 3.9%; N, 7.1%; Cl, 5.0; found: C, 69.9%; H, 4.2%; N, 7.0%.

[0376] DTA: decomposition occurred above about 360° C. in the measurement in air (measurement conditions: 35.0/5.0 (K/min)/720.0).

[0377] f) Crystal Structure Analysis of the Fac Isomer of the Ir Complex (7)

[0378] Crystals suitable for X-ray structure analysis were obtained under an inert gas atmosphere by slow diffusion of pentane into a solution of a fac/mer isomer mixture of the Ir complex (7) in methylene chloride. FIG. 2 shows the crystal structure of the fac isomer of the Ir complex (7). The lengths of the Ir-carbene carbon bonds of the three ligands are 2.034 Å, 1.997 Å and 2.025 Å and thus each correspond to an Ir—C single bond. The pairing of in each case two molecules of the Ir complex (7) via one of the fused-on phenyl rings of each is conspicuous. The average distance between the participating phenyl ring planes is 3.6 Å.

[0379] g) Optical Spectroscopy of the Ir Complex (7)

[0380] Ga) Measurement of Optical Properties as a Function of the Isomer Ratio

[0381] Samples of the Ir complex (7) were measured in a concentration of 2 mg/I in toluene (“spectroscopic grade”). Various samples having different fac-mer isomer ratios were examined.

[0382] gaa) Samples

[0383] The following samples having different isomeric purities were characterized in terms of their optical properties (table 1) and compared below.

TABLE-US-00001 TABLE 1 Composition of the samples for optical spectroscopy Sample # faclmer ratio 1 from example 2c 9:1.sup.a 2 removal of the fac isomer by sublimation.sup.c 2:1.sup.a 3 by column 29:1.sup.b chromatography 4 (example 2d) 1:37.sup.b .sup.a Ratio according to .sup.1H-NMR .sup.b Ratio according to HPLC .sup.c Sublimation is carried out in a high vacuum unit (preliminary diaphragm pump, molecular turbopump) at p = 1 × 10.sup.−5 mbar. The appropriate amount of the substance was placed in a reservoir, the apparatus was carefully evacuated and the temperature was gradually increased. The sublimation was carried out as a fractional sublimation.

[0384] gab) Absorption Spectra of the Ir Complex (7) in Toluene

[0385] Normalized absorption spectra of the samples 1 to 4 in toluene were measured. The spectra of the crude Ir complex (7) (sample 1) and sample 2 in toluene solution cannot be distinguished. The fac isomer (sample 3) is hypsochromically shifted by 6 nm compared to the mer isomer (sample 4) and clearly shows a shoulder at 335 nm. Mathematical superposition of the fac and mer spectra in a ratio of 80/20 is virtually identical to the absorption spectrum of the starting sample (sample 1). This confirms that the starting mixture comprises the two isomers in the weighted ratio z.sub.fac/z.sub.mer of 80/20.

[0386] A normalized absorption spectrum corresponds to the measured optical density relative to the optical density at the absorption maximum; it is concentration-independent and describes only the line shape.

[00001]$O{D}_i^{n\circ rm}\left(\lambda \right)=\frac{O{D}_i\left(\lambda \right)}{O{D}_i^{\max }\left({\lambda }_{\max }\right)}=\frac{{\epsilon }_i\left(\lambda \right)}{{\epsilon }_i^{\max }}$

[0387] In the mathematical superposition:

[00002]$\begin{array}{c}{\mathrm{OD}}_{\mathrm{cal}}^{norm}\left(\lambda \right)=\frac{{\mathrm{OD}}_{\mathrm{fac}}^{\max }{\mathrm{OD}}_{\mathrm{fac}}^{\mathrm{norm}}\left(\lambda \right)+{\mathrm{OD}}_{mer}^{\max }{\mathrm{OD}}_{mer}^{\mathrm{norm}}\left(\lambda \right)}{{\mathrm{OD}}_{\mathrm{fac}}^{\max }+{\mathrm{OD}}_{mer}^{\max }}{N}_{\mathrm{norm}}\\ =\left(z_{\mathrm{fac}}{\mathrm{OD}}_{\mathrm{fac}}^{\mathrm{norm}}\left(\lambda \right)+z_{mer}{\mathrm{OD}}_{\mathrm{fac}}^{\mathrm{norm}}\left(\lambda \right)\right)N_{\mathrm{norm}}\end{array}$$\mathrm{where}$$z_{\mathrm{fac}}+z_{mer}=1$$\mathrm{and}$$z_{\mathrm{fac}}=\frac{O{D}_{\mathrm{fac}}^{\max }}{O{D}_{\mathrm{fac}}^{\max }+O{D}_{mer}^{\max }}$

[0388] The values z.sub.fac and z.sub.mer are the proportions weighted according to the optical density at the absorption maximum and depend on the product of the maximum molar extinction coefficient ϵ.sub.max and the concentration. They are not identical to the mole fractions. These can be obtained from z.sub.fac and z.sub.mer with the aid of the extinction coefficients at the absorption maximum ϵ.sub.max (fac and mer). The ratio z.sub.fac/z.sub.mer is the ratio of the optical densities at the absorption maxima. N.sub.mer is the normalization factor which guarantees that the summated spectrum is normalized to one.

[0389] gac) Emission Spectra of the Ir Complex (7) in Toluene

[0390] Normalized emission spectra of the samples 1 to 4 in toluene were measured. In the emission spectra, fac and mer isomers are clearly distinguishable in terms of shape and position of the maxima. The mer spectrum is clearly shifted bathochromically (emission maxima 395 vs. 461 nm). The contribution of the mer isomer in the mixture is shown by the shoulder at 450 nm in the emission spectrum. The emission band of the fac isomer is significantly narrower. Here too, mathematical superposition of the normalized emission spectra of the two isomers in a ratio of 80/20 gives the spectrum of the starting sample.

[0391] In the mathematical superposition of normalized emission spectra:

[00003]$\begin{array}{c}{I}_{\mathrm{norm}}^{\mathrm{cin}}\left(\lambda \right)=\frac{{\mathrm{OD}}_{\mathrm{fac}}\left({\lambda }_{\mathrm{exc}}\right){\Phi }_{\mathrm{fac}}{I}_{\mathrm{fac}}^{\mathrm{norm}}\left(\lambda \right)+{\mathrm{OD}}_{\mathrm{mer}}\left({\lambda }_{\mathrm{exc}}\right){\Phi }_{\mathrm{mer}}{I}_{\mathrm{mer}}^{\mathrm{norm}}\left(\lambda \right)}{{\mathrm{OD}}_{\mathrm{fac}}\left({\lambda }_{\mathrm{exc}}\right){\Phi }_{\mathrm{fac}}+{\mathrm{OD}}_{\mathrm{mer}}\left({\lambda }_{\mathrm{exc}}\right){\Phi }_{\mathrm{mer}}}{N}_{\mathrm{norm}}\\ =\left(y_{\mathrm{fac}}\left({\lambda }_{\mathrm{exc}}\right)I_{\mathrm{fac}}^{\mathrm{norm}}\left(\lambda \right)+y_{\mathrm{mer}}\left({\lambda }_{\mathrm{exc}}\right)I_{\mathrm{mer}}^{\mathrm{norm}}\left(\lambda \right)\right)N_{\mathrm{norm}}\end{array}$$\mathrm{where}$$y_{\mathrm{fac}}\left({\lambda }_{\mathrm{exc}}\right)+y_{\mathrm{mer}}\left({\lambda }_{\mathrm{exc}}\right)=1$$\mathrm{and}$$y_{\mathrm{fac}}\left({\lambda }_{\mathrm{exc}}\right)=\frac{{\mathrm{OD}}_{\mathrm{fac}}\left({\lambda }_{\mathrm{exc}}\right){\Phi }_{\mathrm{fac}}}{{\mathrm{OD}}_{\mathrm{fac}}\left({\lambda }_{\mathrm{exc}}\right){\Phi }_{\mathrm{fac}}+{\mathrm{OD}}_{\mathrm{mer}}\left({\lambda }_{\mathrm{exc}}\right){\Phi }_{\mathrm{mer}}}$

[0392] The values y.sub.fac and y.sub.mer depend on the excitation wavelength and indicate the proportions of the total emission weighted according to the emission intensity (=product of absorption at the excitation wavelength OD (λ.sub.exc) and quantum yield Φ). They are not identical to the mole fractions. These can be obtained from y.sub.fac and y.sub.mer with the aid of the extinction coefficients at the absorption maximum ϵ.sub.max (fac and mer) and the quantum yields of the two isomers. N.sub.mer is the normalization factor which guarantees that the summated spectrum is normalized to one.

[0393] The measured photoluminescence quantum yields of the four samples in toluene do not vary, both in air-saturated solution and under nitrogen (table 2).

TABLE-US-00002 TABLE 2 Quantum yields of the photoluminescence of the Ir complex (7) in toluene. QY.sup.1) / %, QY.sup.1) / %, air-saturated toluene nitrogen-saturated toluene Exc.sup.2) 325 nm Exc.sup.2) 325 nm Sample 1 0.6 1.3 Sample 2 0.6 1.4 Sample 3 (fac) 0.6 1.3 Sample 4 (mer) not determined 1.4 .sup.1)QY = quantum yield .sup.2)Exc = excitation wavelength

[0394] Compared to measurements in a solid matrix (for example PMMA or diphenyldi-o-tolylsilane (UGH 1)), the emitter displays a luminescence quantum yield in nitrogen-saturated solution which is smaller by an order of magnitude. This influence of quenching by solvent molecules is also reflected in the luminescence decay times of the Ir complex (7): in toluene, nitrogen-saturated: 26.5 ns or 25.8 ns vs. 10% of the complex (7) in UGH 1: 234 ns. The low sensitivity to oxygen is conspicuous. This can be explained by the luminescence decay time in toluene which is short for a triplet emitter. Given the solubility of oxygen in toluene (1.97 10.sup.−3 mol/l) and a decay time of about 26 ns, the bimolecular quenching by oxygen is not very effective. However, the decay time in the solid of 230-250 ns is quite short for a triplet emitter and points to effective spin-orbit coupling.

[0395] gad) Measurement of Absorption and Emission Spectra at Different Fac/Mer Isomer Ratios of the Ir Complex (7) in PMMA Films

[0396] To characterize samples 1 to 4 of the Ir complex (7) further as a diluted solid, corresponding PMMA films were produced. To produce the PMMA film, 2 mg of dye (Ir complex (7), examples 2c and 2d) were dissolved in 1 ml of 10% strength (percent by mass) PMMA solution (PMMA in CH.sub.2Cl.sub.2) and a film was applied to a microscope slide by means of a 60 μm doctor blade. The film dries immediately. The measurements in toluene (spectroscopic grade) were carried out at a concentration of 10 mg/I. To remove the oxygen in the solution, nitrogen (O.sub.2 content<150 ppm) was passed through the solution for 5 minutes before the measurement and nitrogen was passed over the surface of the liquid during the measurement. All measurements were carried out at room temperature.

[0397] Absorption:

[0398] The fac isomer (example 2d) displays a significant hypsochromic shift in the absorption compared to the mer isomer (example 2d) and has a shoulder at 330 nm. The 80/20 superposition of the fac/mer spectra is identical to the absorption spectra of the starting sample. A somewhat conspicuous aspect is the increased absorption of sample 2 by 280 nm. It must not be forgotten here that the absorption spectra are normalized spectra which show only the spectral shape and not the absolute absorption intensity.

[0399] Emission

[0400] The emission spectrum of sample 3 is, as before in toluene and in the powder, significantly narrower and pure blue. Sample 4 has the maximum at 460 nm with a shoulder at 400-410 nm. Here too, a mathematical superposition (80/20) reproduces the spectrum of the mixture.

[0401] The spectra in PMMA largely correspond to those in toluene. However, quenching of the phosphorescence emission plays a role in the solution spectra, which has no influence on the emission spectra but reduces the photoluminescence quantum yield. Table 3 below shows the quantum yields of the 4 samples in PMMA films and the color coordinates.

TABLE-US-00003 TABLE 3 Photoluminescence quantum yields and color coordinates in PMMA. QY.sup.1)/ % in PMMA X.sub.RGB in PMMA Y.sub.RGB in PMMA Sample # Exc.sup.2) 325 nm CIE 1931 CIE 1931 Sample 1 19 0.160 0.078 Sample 2 15 0.160 0.080 Sample 3 (fac) 17 0.160 0.047 Sample 4 (mer) 11 (exc 330 nm) 0.164 0.165 .sup.1)QY = quantum yield .sup.2)Exc = excitation wavelength

[0402] The quantum yield of sample 4 is significantly lower than those of the 3 other samples. In the case of films and at these numerical values, the accuracy of the measurement of the quantum yields is in the region of 2 percentage points, i.e. significantly less accurate than in solution because a film gives poorer definition compared to a solution because it is less homogeneous.

gae) Summary of the Optical Characterization of Complex (7)

[0403] The studies show that the fac isomer and the mer isomer of the Ir complex (7) differ significantly in terms of their spectroscopic properties. Fac-(7) has a photoluminescence quantum yield in the solid of about 20%, which is virtually twice as high as that of mer-(7). While fac-(7) emits in the pure blue region, the emission of mer-(7) extends into turquoise-colored regions. On the basis of the positions of the emission and absorption bands, nonradiated energy transfer from the fac to mer isomer should be possible (virtually not at all in the opposite direction), so that at application-relevant degrees of doping or emitter molecule spacings, any contamination by mer-(7) partly quenches the emission of the fac isomer, independently of the action of the mer isomer as a trap for individual charges. The additional mer emission resulting therefrom has a longer wavelength and is less efficient. This interpretation is supported by the measurement of the concentration dependence of the Ir complex (7) in PMMA films. The use of isomerically pure compounds of the Ir complex (7) is therefore preferred for the construction of devices.

[0404] h) Determination of the Quantum Yield and Emission Properties of the Complex (8) in Toluene and PMMA

[0405] To produce the PMMA film, 2 mg of dye (Ir complex (8)) were dissolved in 1 ml of 10% strength (percent by mass) PMMA solution (PMMA in CH.sub.2Cl.sub.1-2) and a film was applied to a microscope slide by means of a 60 μm doctor blade. The film dries immediately. The measurements in toluene (spectroscopic grade) were carried out at a concentration of 10 mg/I. To remove the oxygen in the solution, nitrogen (O.sub.2 content<150 ppm) was passed through the solution for 5 minutes before the measurement and nitrogen was passed over the surface of the liquid during the measurement. All measurements were carried out at room temperature. At an excitation wavelength of 330 nm, the emitter gives a quantum yield of 10% in PMMA and a quantum yield of 3.6% in toluene. The emission maximum in toluene and PMMA is 512 nm. The CIE coordinates in PMMA are X.sub.RGB=0.302, Y.sub.RGB=0.591.

[0406] 3. Device Construction

[0407] The electroluminescence of the complex (7) (cf. examples 2c, 2d) and of the complex (8) (cf. example 2e) were in each case tested in a device having the following layer structure:

[0408] 3a) Construction of a Device Comprising Complex (7) as Emitter Substance

[0409] The ITO substrate used as anode is firstly cleaned by boiling in isopropanol and acetone. At the same time, it is treated with ultrasound. Finally, the substrates are cleaned in a dishwasher using commercial cleaners for LCD production (Deconex® 20NS and neutralization agent 25ORGANACID®). To eliminate any remaining organic residues, the substrate is exposed to a continuous flow of ozone for 25 minutes. This treatment also improves hole injection, since the work function of the ITO is increased.

[0410] PEDT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)) (Baytron® P VP AI 4083) is subsequently applied to the specimen from aqueous solution by spin coating. A thickness of 46 nm is obtained. This is followed by the emitter layer which is composed of PMMA (polymethyl methacrylate) dissolved in chlorobenzene and the emitter substance (complex (7), example 2c, example 2d). A twenty percent strength by weight solution of PMMA in chlorobenzene is used. The dopant (emitter) is added thereto in various concentrations.

[0411] The 28% strength solution gives a thickness of about 61 nm after application by spin coating and the 40% strength solution gives a thickness of 77 nm. These solutions were prepared using an isomer mixture (fac/mer) of the emitter in which the facial isomer is the main component (example 2c). Furthermore, a 30% strength solution was prepared using the isomerically pure fac emitter (example 2d). After application by spin coating, this solution gives a layer thickness of 27 nm.

[0412] To balance the charge carriers better, 40 nm of BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) are then applied by vapor deposition. BCP is known for its good conductivity for electrons, and it also, owing to its low HOMO, blocks holes which can thus leave the PMMA only with difficulty. Finally, 1 nm of lithium fluoride and 130 nm of aluminum are deposited as cathode.

[0413] To characterize the component (OLED), electroluminescence spectra are then recorded at various currents and voltages. In addition, the current-voltage curve is measured in combination with the luminous power of the emitted light. The luminous power can then be converted into photometric parameters by calibration with a luminance meter.

[0414] The following electrooptical data are thus obtained for the above-described components (OLEDs):

TABLE-US-00004 PMMA layer Emission Photometric External Device thickness maximum efficiency quantum yield Luminance 28% of 61 nm 453 nm 0.8 cd/A    1% 30 cd/m.sup.2 complex 7 (fac/mer).sup.1) 40% of 77 nm 453 nm 0.65 cd/A 0.75% 75 cd/m.sup.2 complex 7 (fac/mer).sup.1) 30% of 27 nm 400 nm 0.53 cd/A  1.5% 80 cd/m.sup.2 complex 7 (pure fac).sup.2) .sup.1)Example 2c .sup.2)Example 2d

[0415] 3b) Construction of a Device Comprising Complex (8) as Emitter Substance

[0416] The ITO substrate used as anode is firstly cleaned with isopropanol at 30° C. in an ultrasonic bath for 10 minutes and then cleaned with chloroform, likewise at 30° C. in an ultrasonic bath, for 10 minutes. The substrate is then treated in an oxygen plasma for 20 minutes to eliminate any remaining organic residues.

[0417] NPD is then vapor-deposited as hole conductor onto the substrate at 2×10.sup.−5 mbar and a deposition rate of 0.2 Å/s, so that a layer thickness of 40 nm is obtained. Complex (8) (example 2e) as 5% strength dopant is subsequently vapor-deposited together with the matrix material CBP. The thickness of this layer is likewise 40 nm. This is followed by the BCP hole-blocking layer (6 nm) and an electron conductor layer comprising Alq.sub.3 having a thickness of 20 nm. Finally, a 1 nm thick LiF layer is applied and the Al electrode is finally vapor-deposited.

[0418] A photometric efficiency of 6.4 cd/A at an emission maximum of 513 nm is obtained for the above-described component (OLED). The maximum luminance is 1487 cd/m.sup.2.