Binuclear non-heme iron catalysts

Details Binuclear non-heme iron catalysts Binuclear non-heme iron catalysts

2000-06-06

2002-05-28

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C556S028000, C556S045000, C556S136000, C556S150000, C564S155000, C564S158000, C568S027000, C568S028000, C568S400000, C568S401000, C568S714000, C568S733000, C568S735000, C568S744000

Reexamination Certificate

active

06395904

ABSTRACT:

FIELD OF THE INVENTION
The present invention is in the field of binuclear non-heme iron compounds. In particular, the invention relates to binuclear iron compounds which are useful as catalysts in the oxidation of various organic substances, such as alkanes, arenes, olefins and sulfides. The invention further relates to a method for preparing alcohols from alkanes, or arenes, epoxides from olefins, ketones from alkanes, sulfoxides and sulfones from sulfides using the binuclear iron compounds.
BACKGROUND OF THE INVENTION
As known petroleum reserves are rapidly depleted, a need exists to secure an alternative source of industrial chemical feedstocks now derived from oil. One approach is to convert relatively abundant coal and natural gases such as methane into synthesis gas, a mixture of carbon monoxide and hydrogen, which can then be transformed into alcohols, acids, esters, etc. Accordingly, the need remains to provide efficient methods to convert hydrocarbons directly into oxidized organics.
Binuclear non-heme iron centers such as those found in the active site of methane monooxygenase (MMO) act as oxygen atom transfer catalysts by a complex, poorly understood mechanism.
1,2
Despite advances in understanding the structural,
3
spectroscopic,
4,5
and mechanistic aspects of enzymatic alkane oxidation,
4,5
attempts to effect hydrocarbon oxidation by a biomimetic mechanism have not succeeded.
1,2
While synthetic non-heme diferric systems are reported to oxygenate substrates in the presence of either dioxygen
6
or alkyl peroxides,
1,2,4,5,7-13
the peroxide chemistry is now thought to be dominated by oxygen-based free radical pathways.
14-17
The present invention provides a catalytically competent binuclear non-heme Fe complexes that can perform biologically relevant oxo-atom transfer chemistry.
18,19
Specifically, the invention provides compounds of the formula [Fe
2
2+
(H
2
Hbamb)
2
(N-MeIm)
2
], 1, [Fe
2+
, Fe
2+
], Scheme 1),
20a
as well as its mixed-valence [Fe
2+
, Fe
3+
], 2, and diferric [Fe
3+
, Fe
3+
], 3, core states, all of which possess remarkable reactivity properties. Thus, both the [Fe
2+
, Fe
2+
, 1, and [Fe
2+
, Fe
3+
], 2, complexes are uniquely capable of catalyzing the oxidation of alkanes, alkenes and sulfides by the known oxygen atom donor, iodosylbenzene (OIPh). The catalytic chemistry of non-heme 1 and 2 parallel that reported for cytochrome P-450, a system believed to involve a porphyrin cation radical (Fe
4+
═O] reactive intermediate.
21-23
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a binuclear metal complex having the structure:
wherein M
1
and M
2
are independently selected from the group consisting of Fe, Co, Mn and Ru; wherein m and n are independently +2 or +3; wherein R
1
, R
2
, R
3
, R
4
, R
5
and R
6
independently a linear C
1
-C
6
alkyl, C
5
-C
6
cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R
1
and R
2
, (ii) R
3
and R
4
, or (iii) R
5
and R
6
independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2≦i+j+k≦4; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+n−4=p×q; wherein (i) R
1
or R
2
and R
3
or R
4
, (ii) R
3
or R
4
and R
4
or R
5
, or (iii) R
1
or R
2
and R
5
or R
6
independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C
1
-C
6
alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate.
Another object of the present invention is to provide a ligand having the structure:
wherein R
1
, R
2
, R
3
, R
4
, R
5
and R
6
are independently and optionally substituted linear C
1
-C
6
alkyl, C
5
-C
6
cycloalkyl or phenyl; wherein R
1
, R
2
, R
3
, R
4
, R
5
and R
6
are independently a linear C
1
-C
6
alkyl C
5
-C
6
cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R
1
and R
2
, (ii) R
3
and R
4
, or (iii) R
5
and R
6
independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2≦i+j+k≦4; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+n−4=p×q; wherein (i) R
1
or R
2
and R
3
or R
4
, (ii) R
3
or R
4
and R
4
or R
5
, or (iii) R
1
or R
2
and R
5
or R
6
independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C
1
-C
6
alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate.
A further object of the invention is to provide a method of preparing an alcohol from an alkane or cycloalkane wherein said alkane or cycloalkane is optionally substituted by an aryl, which comprises:
(A) dissolving the alkane or cycloalkane in a suitable solvent to form a solution; and
(B) treating the solution with an oxygen atom donor in the presence of a binuclear metal complex having the structure:
 wherein M
1
and M
2
are independently selected from the group consisting of Fe , Co, Mn and Ru; wherein m and n are independently +2 or +3; wherein R
1
, R
2
, R
3
, R
4
, R
5
and R
6
are independently a linear C
1
-C
6
alkyl, C
5
-C
6
cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R
1
and R
2
, (ii) R
3
and R
4
, or (iii) R
5
and R
6
independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2≦i+j+k≦4; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+n−4=p×q; wherein (i) R
1
or R
2
and R
3
or R
4
, (ii) R
3
or R
4
and R
4
or R
5
, or (iii) R
1
or R
2
and R
5
or R
6
independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C
1
-C
6
alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate, under suitable conditions to form the alcohol.
A further object is to provide a method of preparing an epoxide from an alkene or cycloalkene, wherein the alkene or cycloalkane is optionally mono-, di-, tri- or tetrasubstituted independently with an optionally substituted linear C
1
-C
6
alkyl, C
5
-C
6
cycloalkyl or phenyl, wh

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