Certain manganese (IV) complex salts, in particular those comprising the dinuclear complex dication [LMn (L-0) 3MnL] 2+ wherein L is the tridentate amine ligand 1,4, 7-trimethyl-1,4, 7- triazacyclononane and whose structure is are known to be efficient oxidation catalysts (G. B. Shul'pin et al. Tetrahedron 1999, 55, 5345-5358; G. B. Shul'pin et al., J. Mol. Catal. A : Chem. 2001, 170, 17-34). They are usually employed as hexafluorophosphates which are soluble in polar organic solvents such as acetonitrile.

The solubility of these complexes is somewhat disadvantageous in that it impedes the work-up of the reaction mixtures after utilizing the complexes as oxidation catalysts and the reusability of the catalysts.

The problem to be solved by the instant invention was therefore to provide insoluble or sparingly soluble manganese (IV) complex salts having comparable or even improved catalytic activity.

According to the invention, this problem has been solved by the manganese (iv) hetero- polymolybdates and-tungstates of the formula [LMn (p-O) 3MnL)] n [XMI2040] m (I), wherein L is 1, 4, 7-trimethyl-1, 4-7-triazacyclononane, X is P or Si, M is Mo or W, n is 2 or 3, and m is 1 or 2, with the provisos that

(i) if X is Si, then n = 2 and m = 1 and (ii) if X is P, then n = 3 and m = 2.

It has been found that these complex salts are virtually insoluble in all common solvents, and nevertheless their catalytic activity is comparable or even superior to that of the correspondimg soluble hexafluorophosphate. Due to their insolublity, they can easily and completely be removed (e. g. , by filtration, the residual Mn and M content of the filtrate being <10 ppm) from the reaction mixture after completion of the oxidation and may be reused several times without significant loss of activity. It is also possible to dilute the complex salts of the invention with suitable solid inert materials (e. g. , silica) and use the thus obtained mixtures as catalysts in fixed-bed reactors (e. g. , packed columns) for continuous or semi-continuous liquid-phase reactions.

The manganese (iv) complex salts of the invention may be easily prepared by reacting a solution of the above mentioned hexafluorophosphate of formula [LMn (1-0) 3MnL) ] (PF6) 2, wherein L is L is 1, 4, 7-trimethyl-1, 4-7-triazacyclononane, with a heteropolyacid of formula H. XM, 204o wherein X and M are as defined above, o = 4 for X = Si and o = 3 for X = P, and sub- sequently isolating the precipitated manganese (tv) heteropolyacid complex salt.

The preparation is preferably carried out using acetonitrile as solvent for the hexafluoro- phosphate and water or a lower alcohol, in particular methanol or ethanol, or an aqueous lower alcohol as solvent for the heteropolyacid.

The manganese (iv) complex salts of the invention can be used as catalysts in the partial oxidation of organic compounds with peroxy compounds.

Preferred peroxy compounds are hydrogen peroxide, peroxycarboxylic acids and mixtures thereof. It should be noted that hydrogen peroxide reacts with carboxylic acids to give peroxycarboxylic acids in an equilibrium reaction.

It is also possible to use other peroxy compounds, for example, tert-butyl hydroperoxide.

A preferred use of the manganese (IV) complex salts of the invention is their use as catalysts in a process for the production of aldehydes and/or carboxylic acids of formula R'-CHO (II) and/or R'-COOH (III), wherein R'is linear or branched C1-10-alkiyl, aryl or aryl-C4-alkyl, which process comprises reacting an alcohol of formula Rl-CH2OH (IV), wherein R'is as defined above, with a peroxy compound.

Depending on the reaction conditions and the residue R'the product is either an aldehyde or a carboxylic acid or a mixture thereof.

Linear or branched C1-10-alkyl groups are here and hereinbelow, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, hexyl, heptyl, octyl, nonyl and decyl, including all isomers of these groups.

Aryl groups are preferably phenyl or naphthyl, optionally substituted with one or more halogen atoms, C_l0-alkyl or C, _, o-alkoxy groups.

Aryl-Cl-alkyl groups are Cl-alkyl groups substituted with the aryl groups defined above. In particular, aryl-C,-alkyl groups are groups such as benzyl, 1-phenylethyl, 2-phenylethyl or 3-phenylpropyl.

Another preferred use of the manganese (IV) complex salts of the invention is their use as catalysts in a process for the production of ketones of formuls R2-C(=O)-R3(V),

wherein R2 and R3 are independently linear or branched Cl-lo-alkyl, aryl or aryl-Cl-alkyl ; or R2 and R3 together with the carbonyl group form a carbocyclic ring, which process comprises reacting an alcohol of formula R2_cHoH-R3 (VI), wherein R2 and R3 are as defined above, with a peroxy compound.

Ketones of formula (V) wherein R2 and R3 together with the carbonyl group form a carbo- cyclic ring are, for example, cyclic C3_8-ketones such as cyclopropanone, cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone or cyclooctanone.

Still another preferred use of the manganese (tv) complex salts of the invention is their use as catalysts in a process for the production of 1,4-cyclohexanedione, which process com- prises reacting 1,4-cyclohexanediol with a peroxy compound.

Still another preferred use of the manganese (tv) complex salts of the invention is their use as catalysts in a process for the production of oxiranes of formula wherein R4, R5, R6 and R7 are independently hydrogen, linear or branched C1-10-alkyl, aryl or aryl-C1-4-alkyl ; or R4 and R5 together with the adjacent carbon atoms form a carbocyclic ring and R6 and R7 are as defined above, which process comprises reacting an olefin of formula

wherein R4, R5, R6 and R7 are as defined above for formula (VII), with a peroxy compound.

Olefins of formula (VIII) wherein R4 and R5 together with the adjacent carbon atoms form a carbocyclic ring are, for example, cyclopentene, cyclohexene or cycloheptene or the various terpene-derived cyclic olefins such as a-pinene.

Another preferred use of the manganese (lV) complex salts of the invention is their use as catalysts in a process for the oxidation of aliphatic, alicyclic or araliphatic hydrocarbons to the corresponding hydroxy or keto compounds, which process comprises reacting said hydrocarbons with a peroxy compound. Alicyclic hydrocarbons suitable for this process are, for example, cyclopentane or cyclohexane which may be oxidized to the correspond- ing cycloalkanols or cycloalkanones or mixtures thereof. Araliphatic hydrocarbons suitable for this process are, for example, diphenylmethane or tetrahydronaphthalene which may be oxidized to benzhydrol and benzophenone or 1,2, 3, 4-tetrahydro-1-naphthol and a-tetralone, respectively.

In a preferred embodiment of the above processes using the manganese (tv) complex salts of the invention, a C2-6-alkanoic acid is used as an additive, acetic acid being especially preferred.

The following non-limiting examples illustrate the preparation of the manganese (iv) complex salts of the invention and their use as oxidation catalysts.

Example 1 Synthesis of [LMn (p-O) 3MnL] (PF6) 2 A mixture of 1.98 g (10 mmol) of MnCl2 4H2O, 1.93 ml (1.71 g, 10 mmol) of 1, 4,7-tri- methyl-1, 4,7-triazacyclononane and 2.76 g (15 mmol) of potassium hexafluorophosphate in 60 ml of ethanol/water (2: 1) was heated for 20 min at 50 °C and subsequently cooled to 0 °C. To the resulting reaction mixture were added 10 ml (10 mmol) of 1 M aqueous hydrogen peroxide and 15 ml (15 mmol) of 1 M aqueous NaOH dropwise. During the addition the solution turned from brown to red. The mixture was then warmed up to room

temperature, 2 M aqueous H2SO4 was dropwise added till a pH = 8 was reached and then stirred 1 h at room temperature. The resulting solution was then filtered over Celtes and the filter cake washed 3 times with 20 ml of acetonitrile. The solution was then dried in vacuo (without heating). The residue was dissolved in 50 ml of acetonitrile and filtered over Celte@. The volume of the clear solution was then reduced to 20 ml. Slow addition of 120 ml of diethyl ether caused the precipitation of [LMn (p-O) 3MnL] (PF6) 2 as a red-orange microcrystalline solid. Prolonged drying in vacuo gave 3.2 g of the title compound (81% of theory).

Elemental analysis: [LMn (u-0) 3MnL] (PF6) 2 = C, 8H42F, 2Mn2N603P2, 790.37 g/mol.

Calcd.: C, 27. 35 ; H, 5. 36 ; N, 10.6. Found: C, 25. 9; H, 5.1 ; N, 10.1.

Example 2 Synthesis of [LMn (u-0) 3MnL] 2 [SiWl2040] A solution of 1.37 g (1.73 mmol) of [LMn (p-O) 3MnL] (PF6) 2 in 20 ml of acetonitrile was added dropwise at room temperature to a solution of 2.80 g (0.97 mmol) of H4SiW, 204o-xH20 in 20 ml of ethanol/water (2: 1). This resulted in the formation of a dark- orange solid. After that, 60 ml of methanol were added and the suspension was stirred for 1 h. After filtration the light orange solid obtained was washed twice with 20 ml of water, 20 ml of methanol and 20 ml of diethyl ether. The resulting solid was dried 1.5 h in vacuo (125 mbar, 35 °C) to give 3.07 g of the title compound as a light orange solid (81% of theory).

Elemental analysis: [LMn (u-0) 3MnL] 2 [SiW12O40] = C36Hs4Mn4N 2046SiWl 2, 3875. 02 g/mol. Water content = 5.7%. Calcd. : C, 11.16 ; H, 2.18 ; N, 4.34. Calcd with 5.7% water: C, 10. 55 ; H, 2.63 ; N, 4.10. Found: C, 8.7 ; H, 1.8 ; N, 3.4.

Example 3 Synthesis of #LMn(µ-O)3MnL]3[PW12O40]2 The preparation was analogous to the one described in the preceding example, using 0.79 g (1.00 mmol) of [LMn (u-0) 3MnL] (PF6) 2 in 20 ml of acetonitrile and 2.88 g (1. 00 mmol) of H3PW i 204o'xH20 in 20 ml of methanol. After work up 2 g of the light orange product [LMn (µ-O) 3MnL] 3 [PW) 204o] 2 were obtained (83% of theory).

Elemental analysis: [LMn (u-0) 3MnL] 3 [PW12O40]2 = C54H126Mn6N18O89P2W24, 7255.38 g/mol Water content = 1.9%. Calcd.: C, 11.16 ; H, 2.18 ; N, 4.34. Calcd. with 1.9% water: C, 8.94 ; H, 1.89 ; N, 3.47. Found: C, 8.8 ; H, 1.7 ; N, 3.4.

Example 4 Synthesis of [LMn (µ-O) 3MnL] 3 [PMol204o] 2 The preparation was analogous to the one described in example 2, using 0.24 g (0.30 mmol) of [LMn (u-0) 3MnL] (PF6) 2 in 20 ml of acetonitrile and 0.55 g (0.30 mmol) of H3PMo12O40#xH2O in 20 ml of methanol. After work up 0.54 g of the brown product [LMn (µ-O) 3MnL] 3 [PMol2040] 2 were obtained (83% of theory).

Elemental analysis: [LMn (µ-O) 3MnL] 3 [PMo12O40]2 = C54H126Mn6N18O89P2Mo24, 5145.78 g/mol Water content = 3.5%. Calcd.: C, 12.60 ; H, 2.47 ; N, 4.90. Calcd. with 3.5% water: C, 12.17 ; H, 2.74 ; N, 4.73. Found: C, 13.4 ; H, 2.4 ; N, 5.0.

Examples 5-15 Oxidation Reactions General procedure : In a 25 ml round bottom flask were introduced 9.24 mmol of substrate, 5 ml of acetonitrile, 0. 014 mmol of acetic acid, 100 ui ofchlorobenzene (internal standard) and 10 wt. -% of catalyst. Under vigourous stirring at 25 °C, a solution of 130.8 mmol of hydrogen peroxide in 5 ml of acetonitrile was added within 15 to 30 minutes. Stirring was continued for 2 h at the same temperature.

Examples 5-10 Oxidation of alcohols Example 5 Substrate: benzyl alcohol, 0.997 g Catalyst: [LMn (t-0) 3MnL] 3 [PWI204012, 0.100 g Conversion: >98% Yield: >98% benzoic acid.

Example 6 Substrate: 1-hexanol, 0.943 g Catalyst: [LMn (li-0) 3MnL] 3 [PW12O40]2, 0.100 g Conversion: 65% Yield: 25% hexanal, 40% hexanoic acid Example 7 Substrate: 2-hexanol, 0.943 g Catalyst: [LMn (µ-O) 3MnL] 3 [PW, 204o] 2, 0. 100 g Conversion: 100% Yield: 80% 2-hexanone

Example 8 Substrate: 2-octanol, 1.20 g Catalyst: [LMn(µ-O)3MnL]3[PW12O40]2, 0. 100 g Conversion: 55% Yield: 45% 2-octanone Example 9 Substrate: cyclohexanol, 0.924 g Catalyst: [LMn (p-O) 3MnL] 3 [PW12O40]2, 0. 100 g Conversion: 80% Yield: 80% cyclohexanone Example 10 Substrate: 1, 4-cyclohexanediol, 1.072 g Catalyst: [LMn (u-0) 3MnL] 2 [SiWl2040], 0.100 g Conversion: 100% Yield: >98% 1,4-cyclohexanedione The same catalyst was repeatedly used, whereby its activity decreased by less than 4% after 5 oxidation batches.

Examples 11-13 Epoxidation of Olefins Example 11 Substrate: cyclohexene, 0.758 g Catalyst: [LMn(µ-O)3MnL]2[SiW12O40], 0.080 g Conversion: >75% Yield: >50% 7-oxabicyclo [4.1. 0] heptane (cyclohexeneoxide) Example 12 Substrate: styrene, 0.962 g Catalyst: [LMn (p-O) 3MnL] 2 [SiW,204o], 0.100 g

Conversion: 50% Yield: 30% phenyloxirane Example 13 Substrate: 1-hexene, 0.776 g Catalyst: [LMn (µ-O) 3MnL] 2 [SiW12O40], 0.80 g Conversion: 55% Yield: 55% n-butyloxirane Examples 14-15 Oxidation of cycloalkanes Example 14 Substrate: cyclohexane, 0.776 g Catalyst: [LMn (p-O) 3MnL] 2 [SiWi2040], 0.080 g Conversion: >60% Yield: >36% cyclohexanol, 8% cyclohexanone.

Example 15 Substrate: 1,2, 3,4-tetrahydronaphthalene, 1. 220 g Catalyst: [LMn (µ-O) 3MnL] 2 [SiW, 204o], 0.100 g Conversion: 60% Yield: 30% 1,2, 3, 4-tetrahydro-l-naphthol, 25% 3, 4-dihydro-1 (2H)-naphthalenone (a-tetralone).