Platinum(II) and palladium(II) complexes of N-benzoyl-N ′-propylthiourea (H2L): synthesis and geometric isomer distribution of [M(H2L-S )2X2] (M = PtII or PdII; X = Cl−, Br− or I−); crystal structure of trans-[Pd(H2L-S )2Br2]

A systematic study of the synthesis and cis/trans isomer distribution for simple [M(H2L-S)(2)X-2] complexes (M = Pt-II or Pd-II: X = Cl, Br or I; H2L = N-benzoyl-N'-propylthiourea) has shown that the pure cis-[Pt(H2L-S)(2)Cl-2] complex is obtained prior to recrystallization. The cis-[Pt(H2L-S)(2)Cl-2] complex undergoes facile isomerization in a variety of organic solvents, the equilibrium cis/trans distribution of which depends on solvent polarity. The corresponding bromo- and iodo-complexes of Pt-II tend toward mainly the trans isomers, as do the corresponding palladium(II) complexes. The crystal structure of trans-[Pd(H2L-S)(2)Br-2] has been determined which is the first example of a palladium(II) complex in which the potentially chelating ligand is bound through the S atom only.