Cyclopropenylidene-stabilized phosphenium cations
Phosphenium compounds with the general formula I: in which R 1 , R 2 , R 3 and R 4 are identical or different and represent a linear or branched C 1 -C 6 -alkyl radical, which can optionally be substituted, or R 1 and R 2 and/or R 3 and R 4 are bonded to one another with the formation of a ring, R 5 and R 6 stand for a saturated or unsaturated and linear or branched alkyl group, alkenyl group or aryl group, which can have suitable substituents, even heteroatoms as substituents, or a heteroatom-comprising hydrocarbon group, which can have suitable substituents, and the R 5 and R 6 radicals can form a ring which can be 4- to 20-membered, saturated or unsaturated and alicyclic or heteroalicyclic and can exhibit suitable substituents, X − represents an anion, a process for the preparation thereof, and also the use of these compounds in metal complexes which can be used as catalysts in organic synthesis, are claimed.
1. A phosphenium compound with the general formula I:
in which R 1 , R 2 , R 3 and R 4 are identical or different and represent a linear or branched C 1 -C 6 -alkyl radical, which can optionally be substituted, or R 1 and R 2 and/or R 3 and R 4 are bonded to one another with the formation of a ring,
R 5 and R 6 stand for a saturated or unsaturated and linear or branched alkyl group, alkenyl group or aryl group, which can have suitable substituents, or a heteroatom-comprising hydrocarbon group, which can have suitable substituents, and the R 5 and R 6 radicals can form a ring which can be 4- to 20-membered, saturated or unsaturated and alicyclic or heteroalicyclic and can exhibit suitable substituents, and
X − represents an anion chosen from BF 4 − , PF 6 − , SbF 6 − and/or BPh 4 − .
2. The phosphenium compound as claimed in claim 1 , wherein R 1 , R 2 , R 3 and R 4 , each independently of one another, are chosen from isopropyl and tert-butyl.
3. A process for the preparation of the phosphenium compound with the general formula I as claimed in claim 1 , said process comprising: reacting the halocyclopropenium salt with the general formula II:
in which R 1 , R 2 , R 3 and R 4 are defined in claim 1 and Y represents a halogen atom, with a phosphine of the general formula III:
HPR 5 R 6 III
in which R 5 and R 6 are defined as in claim 1 .
4. The process as claimed in claim 3 , wherein Y represents chlorine.
5. A metal complex comprising as a ligand a phosphenium compound of the general formula I:
in which R 1 , R 2 , R 3 and R 4 are identical or different and represent a linear or branched C 1 -C 6 -alkyl radical, which can optionally be substituted, or R 1 and R 2 and/or R 3 and R 4 are bonded to one another with the formation of a ring,
R 5 and R 6 stand for a saturated or unsaturated and linear or branched alkyl group, alkenyl group or aryl group, which can have suitable substituents, or a heteroatom-comprising hydrocarbon group, which can have suitable substituents, and the R 5 and R 6 radicals can form a ring which can be 4- to 20-membered, saturated or unsaturated and alicyclic or heteroalicyclic and can exhibit suitable substituents, and
X − represents an anion.
6. A metal complex as claimed in claim 5 , having the general formula IV:
in which R 1 , R 2 , R 3 and R 4 are identical or different and represent a linear or branched C 1 -C 6 -alkyl radical, which can optionally be substituted, or R 1 and R 2 and/or R 3 and R 4 are bonded to one another with the formation of a ring,
R 5 and R 6 stand for a saturated or unsaturated and linear or branched alkyl group, alkenyl group or aryl group, which can have suitable substituents, or a heteroatom-comprising hydrocarbon group, which can have suitable substituents, and the R 5 and R 6 radicals can form a ring which can be 4- to 20-membered, saturated or unsaturated and alicyclic or heteroalicyclic and can exhibit suitable substituents,
X − represents an anion,
M represents a metal atom chosen from the group consisting of B, Cu, Ag, Au, Ru, Rh, Pd, Os, Ir and Pt,
L represents n identical or different ligands and n represents a number from 1 to 3.
7. The metal complex as claimed in claim 6 , wherein the ligands L are chosen from halogen, CN, CO, alkenes, cycloalkenes and/or alkynes.
8. The metal complex as claimed in claim 6 , wherein ML n represents AuCl, AuCl 3 , PdCl(allyl), RhCl(cod), RhCl(CO) 2 , CuCl, RhCl 4 − and/or BH 3 .
9. A cycloisomerization reaction catalyzed by the metal complex as claimed in claim 6 .
10. The phosphenium compound as claimed in claim 1 , wherein:
R 1 , R 2 , R 3 and R 4 , each independently of one another, are chosen from isopropyl and tert-butyl; and
R 5 and R 6 , each independently of one another, are chosen from linear, branched or cyclic alkyl, alkenyl, or aryl, each of which is unsubstituted or substituted.
11. A phosphenium compound with the general formula I:
in which R 1 , R 2 , R 3 and R 4 are identical or different and are chosen from isopropyl and tert-butyl,
R 5 and R 6 stand for a saturated or unsaturated and linear or branched alkyl group, alkenyl group or aryl group, which can have suitable substituents, or a heteroatom-comprising hydrocarbon group, which can have suitable substituents, and the R 5 and R 6 radicals can form a ring which can be 4- to 20-membered, saturated or unsaturated and alicyclic or heteroalicyclic and can exhibit suitable substituents, and
X − represents an anion.
12. The phosphenium compound as claimed in claim 11 , wherein X − is chosen from BF 4 − , PF 6 − , SbF 6 − and/or BPh 4 − .