Palladium selenolates via oxidative addition of organylselenenyl halides to palladium(0) precursor and via cleavage reaction of diselenides: Synthesis, structure and spectroscopic investigation

Abstract

Oxidative addition of bis[2-(4,4-dimethyl-2-oxazolinyl)phenyl] diselenide to Pd(PPh(3))(4) provided two different mononuclear palladium selenolato complexes, Pd(Se boolean AND N)(PPh(3))Cl (4) [Se boolean AND N = chelating 2-(4,4-dimethyl-2-oxazolinyl)phenylselenolate] and Pd(Se boolean AND N)(Se boolean AND N*)(PPh(3)) (5) [Se boolean AND N = chelating, Se boolean AND N* = non-chelating 2-(4,4-dimethyl-2-oxazolinyl)phenylselenolato ligand] in dicholoromethane and toluene respectively. Complex 4 has also been synthesized by the oxidative addition of 2-(4,4-dimethyl-2-oxazolinyl)phenylselenenyl chloride to Pd(PPh(3))(4). The bromo and iodo analogs of 4 (9 and 10) were similarly synthesized by the oxidative addition of 2-(4,4-dimethyl-2-oxazolinyl) phenylselenenyl bromide and iodide, respectively to Pd(PPh(3))(4). The oxidative addition of 2-(N,N-dimethylaminomethyl)phenylselenenyl bromide and iodide to Pd(PPh(3))(4) afforded mononuclear palladium selenolate complexes, Pd(Se boolean AND N)(PPh(3)) X (13 and 14) [Se boolean AND N = chelating 2-(N,N-dimethylaminomethyl)phenylselenolate, X = Br: 13, X = 1:14]. The reactions of bis[2-(4,4-dimethyl-2-oxazolinyl) phenyl] diselenide and bis[2-(N, N-dimethylaminomethyl) phenyl] diselenide with Pd(COD)Cl(2) provided dinuclear selenolato-bridged complexes [PdCl(Se boolean AND N)](2) (15) [Se boolean AND N = chelating 2-(4,4-dimethyl-2-oxazolinyl)phenylselenolate] and [PdCl(Se boolean AND N)](2) (19) [Se boolean AND N = chelating 2-(N,N-dimethylaminomethyl)phenylselenolate] respectively. The complexes were characterized by elemental analysis and NMR ((1)H and (77)Se) spectroscopy. Complexes 4 and 5 were also characterized by mass spectrometry. Molecular structures of 4, 5, 9, 14 and 15 have been established by single crystal X-ray diffraction analysis. Complexes 4 and 9 are isomorphous and crystallize in the space group P2(1)/c of the monoclinic system where the selenolato and halo ligands are trans to each other. Complex 5 crystallizes in the space group P2(1)/n of the monoclinic system where one chelating and one non-chelating selenolato ligands are trans to each other. Mononuclear complex 14 and binuclear centrosymmetric complex 15 crystallize in the P (1) over bar space group of the triclinic system.