paper20135

Synthesis, structural and theoretical studies of Pd (II) complexes containing an orthometallated C, C-chelating phosphorus ylide

Synthesis, structural and theoretical studies of Pd(II) complexes

containing an orthometallated C,C-chelating phosphorus ylide

Kazem Karami a,⇑, Mina Salimian a, Mahboubeh Hosseini-Kharat a, Giuseppe Bruno b,

Hadi Amiri Rudbari b, Hossein Tavakol a

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

b Dipartimento di Chimica Inorganica, Università di Messina, Vill. S. Agata, Salita Sperone 31, 98166 Messina, Italy

Polyhedron 61 (2013) 143–150

a b s t r a c t

The phosphorus ylide [Ph3PCHC(O)C6H4–NO2-4] (1) reacted with Pd(OAc)2 to give the C,C-orthometallated

complexes [Pd{j2(C,C)–C6H4PPh2C(H)CO(C6H4–NO2-4)}(l-X)]2 (X = Cl (2); X = Br (3)) as a mixture of

isomers, which underwent bridge cleavage reactions with monodentate ligands to afford the monomeric,

neutral Pd(II) complexes [Pd{j2(C,C)–C6H4PPh2C(H)CO(C6H4–NO2-4)}X(L)] (X = Cl, L = Me3Py (4), PPh3

(5); X = Br, L = Me3Py (6), 4-MePy (7), PPh3 (8). The complexes were identified and characterized by spectroscopic

studies (IR and NMR). The X-ray single crystal analysis of 6 and 7 revealed the presence of an

orthometallated C6H4-2-PPh2 unit and a C-linked ylide, PdC(H). In the crystal structure of 6, the location

of the Me3Py ligand is trans to the PdCylide, according to the anti-symbiotic effect, whereas in 7 the 4-

MePy ligand is preferentially cis to the PdCylide. Density functional theory (DFT) calculations in the reaction

solvent (dichloromethane) indicated that the trans isomers of 6 and 7 are 3.03 and 0.70 kcal/mol

more stable than their cis isomers, respectively.

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