paper20141

Structural and theoretical studies of mono and di-insertion of

symmetric alkynes into the PdeC s bond of cyclopalladated secondary

(tert-butyl and ethyl) benzylamines

Kazem Karami a,*, Mahboubeh Hosseini-Kharat a, Corrado Rizzoli b, Hossein Tavakol a,

Janusz Lipkowski c

a Department of Chemistry, Isfahan University of Technology, Isfahan 84156/83111, Iran

b Department of Chemistry, University of Parma, I-43124 Parma, Italy

c Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland

Journal of Organometallic Chemistry 752 (2014) 152e160

Abstract

The reactivity of the dinuclear cyclopalladated complexes derived from secondary benzylamines,

[Pd2{(C,N)eC6H4CH2NH(R)}2(m-X)2] [X ¼ Br, R ¼ t-Bu (1a); X ¼ Cl, R ¼ t-Bu (1b); X ¼ Cl, R ¼ Et (1c)] is

reported. 1a reacted with dimethyl acetylenedicarboxylate (DMAD) to yield the mono-inserted complex

[Pd2{(C,N)eC(CO2Me)]C(CO2Me)C6H4CH2NH(t-Bu)}2(m-Br)2] (2a). 1a, 1b and 1c reacted with (R0)

C^C(R0) (R0 ¼ CO2Me, Ph) to give [Pd{(C,N) C(R0)]C(R0)C(R0)]C(R0)C6H4CH2NH(R)}X] [X ¼ Br, R ¼ t-Bu,

R0 ¼ CO2Me (3a); X ¼ Cl, R ¼ t-Bu, R0 ¼ Ph (2b); X ¼ Cl, R ¼ Et, R0 ¼ Ph (2c)] through a double insertion of

the alkyne into the PdeC s bond. 2c also reacts with Ag(CF3SO3) and pyridine to give mononuclear

cationic complex [Pd{(C,N)eC(Ph)]C(Ph)C(Ph)]C(Ph)}C6H4CH2NH(Et)(py)]CF3SO3 (3c). The crystal

structures of di-inserted complexes 2b, 2c and 3c have been determined by X-ray diffraction studies.

Their molecular structures showed that the conformation of the C]C double bonds within the butadienyl

group attached to the aromatic ring was transecis. Density functional theory (DFT) calculations

also indicated that this arrangement is more stable than other possible conformations.

فرم جستجو