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Keywords:

  • carbenes;
  • diphosphines;
  • N,S-heterocycles;
  • ruthenium;
  • transfer hydrogenation

Abstract

Phosphine exchange of [RuIIBr(MeCOO)(PPh3)2(3-RBzTh)] (3-RBzTh=3-benzylbenzothiazol-2-ylidene) with a series of diphosphines (bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethylene (dppv), 1,1′-bis(diphenylphosphino)ferrocene (dppf), 1,4-bis(diphenylphosphino)butane (dppb), and 1,3-(diphenylphosphino)propane (dppp)) gave mononuclear and neutral octahedral complexes [RuBr(MeCOO)(η2-P2)(3-RBzTh)] (P2=dppm (2), dppv (3), dppf (4), dppb (5), or dppp (6)), the coordination spheres of which contained four different ligands, namely, a chelating diphosphine, carboxylate, N,S-heterocyclic carbene (NSHC), and a bromide. Two geometric isomers of 6 (6a and 6 b) have been isolated. The structures of these products, which have been elucidated by single-crystal X-ray crystallography, show two structural types, I and II, depending on the relative dispositions of the ligands. Type I structures contain a carbenic carbon atom trans to the oxygen atom, whereas two phosphorus atoms are trans to bromine and oxygen atoms. The type II system comprises a carbene carbon atom trans to one of the phosphorus atoms, whereas the other phosphorus is trans to the oxygen atom, with the bromine trans to the remaining oxygen atom. Complexes 2, 3, 4, and 6a belong to type I, whereas 5 and 6 b are of type II. The kinetic product 6 b eventually converts into 6a upon standing. These complexes are active towards catalytic reduction of para-methyl acetophenone by 2-propanol at 82 °C under 1 % catalyst load giving the corresponding alcohols. The dppm complex 2 shows the good yields (91–97 %) towards selected ketones.

Featured Compounds

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  1. 1 - 4
Compound 3
Molecular Weight:862.74
Molecular Formula:C42H37BrNO2P2RuS
InChIKey:QHLPOOHLNJFHQF-IKTCFUDCSA-L
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Compound 5
Molecular Weight:892.8
Molecular Formula:C44H43BrNO2P2RuS
InChIKey:HPKXLLCIXOZMGR-UHFFFAOYSA-L
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Compound 6a
Molecular Weight:878.78
Molecular Formula:C43H41BrNO2P2RuS
InChIKey:RIQAOZKSMHQHIX-UHFFFAOYSA-L
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Compound 1
Molecular Weight:990.91
Molecular Formula:C52H45BrNO2P2RuS
InChIKey:APERQKUQCSJTPA-UHFFFAOYSA-L
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