Synthesis, spectroscopic, and structural studies of the methylpalladium(II) complexes [{PdMe(SMe₂)X}₂](X = Cl, Br, or I); crystal structure of trans-[{PdMe(SMe₂)(µ-Cl)}₂]

The complexes [{PdMe(SMe₂)X}₂](X = Cl, Br, or I) have been prepared by reaction of trans[Pd(SMe₂)₂X₂] with halide-free methyl-lithium (X = Cl or Br), and reaction of trans-[Pd(SMe₂)₂Cl₂] with methyl-lithium containing lithium iodide (X = I) in diethyl ether at –60 to –15 °C under nitrogen. Other synthetic routes to the bromo- and iodo-complexes are also described. The crystal structure of the chloro-complex [{PdMe(SMe₂)(µ-Cl)}₂] has been determined by single-crystal X-ray diffraction at 295 K and refined by least-squares methods to R= 0.025 for 1 914 independent ‘observed’ reflections [space group P2₁/n, a= 10.792(4), b= 7.373(2), c= 9.131(5)Å, β= 109.03(3)°, and Z= 2]. The centrosymmetric dimeric molecules have trans stereochemistry with bridging chloro-groups and square-planar geometry for palladium(II). ¹H N.m.r. and far-i.r. spectra, and molecular weight determinations are consistent with similar structures for the bromoand iodo-complexes.