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Synthesis of the first C-2 cyclopalladated derivatives of 1,3-Bis(2-pyridyl)benzene: crystal structures of [Hg(N-C-N)Cl], [Pd(N-C-N)Cl], and [Pd2(N-C-N)2(μ-OAc)]2[Hg2Cl6]: catalytic activity in the Heck reaction

Soro, Barbara and Stoccoro, Sergio and Minghetti, Giovanni and Zucca, Antonio and Cinellu, Maria Agostina and Gladiali, Serafino Gabriele and Manassero, Mario and Sansoni, Mirella (2005) Synthesis of the first C-2 cyclopalladated derivatives of 1,3-Bis(2-pyridyl)benzene: crystal structures of [Hg(N-C-N)Cl], [Pd(N-C-N)Cl], and [Pd2(N-C-N)2(μ-OAc)]2[Hg2Cl6]: catalytic activity in the Heck reaction. Organometallics, Vol. 24 (1), p. 53-61. eISSN 1520-6041. Article.

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DOI: 10.1021/om040102o

Abstract

The synthesis of C-2 cyclopalladated derivatives of 1,3-bis(2-pyridyl)benzene (N-CH-N) has been achieved for the first time through a transmetalation reaction. C-2 mono- and dinuclear complexes have been obtained by reaction of Pd(OAc)2 and the organomercury(II) compound [Hg(N-C-N)Cl] (1) as precursors. The new species 2−11 were characterized in solution and, in the case of [Pd(N-C-N)Cl] (2) and [Pd2(N-C-N)2(OAc)]2[Hg2Cl6] (11) as well as of [Hg(N-C-N)Cl] (1), in the solid state. The X-ray crystal structures unambiguously show the pincer behavior of the N-C-N ligand in the palladium species and the linear coordination C−Hg−Cl in the mercury precursor. Displacement of the coordinated halide gives cationic species such as [Pd(N-C-N)(H2O)][BF4] (5) or, in the absence of donor solvents or anions, the dinuclear halide-bridged species [Pd2(N-C-N)2(μ-X)][BAr‘4] (X = Cl (6), Br (7), I (8); Ar‘ = 3,5-(CF3)2-C6H3). For comparison purposes [Pd(N-C-N)(OAc)] (9) and [Pd2(N-C-N)2(μ-OAc)][BAr‘4] (10) were also prepared. The mononuclear complexes 2, 4, 5, and 9 are high-performance catalysts in the Heck reaction of iodobenzene and methyl acrylate, even at moderate temperatures. Under microwave heating a turnover frequency as high as 280 000 h-1 is observed with complex 2 at the nominal temperature of 135 °C.

Item Type:Article
ID Code:4293
Status:Published
Refereed:Yes
Uncontrolled Keywords:C-2 cyclopalladated derivatives, Heck reaction
Subjects:Area 03 - Scienze chimiche > CHIM/03 Chimica generale e inorganica
Area 03 - Scienze chimiche > CHIM/04 Chimica industriale
Divisions:001 Università di Sassari > 01 Dipartimenti > Chimica
Publisher:American Chemical Society
eISSN:1520-6041
Deposited On:28 Jul 2010 16:49

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