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]

Abstract

A systematic study of the synthesis and cis/trans isomer distribution for simple [M(H₂L-S)₂X₂] 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)₂Cl₂] complex is obtained prior to recrystallization. The cis-[Pt(H₂L-S)₂Cl₂] 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)₂Br₂] 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.