Rhenium complexes with di- and tri-thiolate ligands. The synthesis and X-ray crystal structures of square pyramidal [PPh4][ReO(SCH2CH2S)2] and [NMe4][ReS(SCH2CH2S)2] and trigonal prismatic [PPh4][Re{(SCH2)3CCH3}2]

Abstract

The complexes [PPh₄][ReO(SCH₂CH₂S)₂](1), [NMe₄][ReS(SCH₂CH₂S)₂](3), and [PPh₄][Re{(SCH₂)₃CCH₃}₂](5) have been synthesised by the reactions of K₂[ReCl₆] or [ReOCl₃(PPh₃)₂] with the respective polythiol in the presence of triethylamine in methanol solution. Complex (1) crystallises in space group Pcab with a= 15.122(3), b= 18.685(4), c= 19.648(4)Å, U= 5 542.02 ų, and Z= 4. Structure solution based on 2 072 independent reflections was refined to R= 0.063. Complex (3) crystallises in space group P2₁/c with a= 9.539(3), b= 15.123(4), c= 21.815(4)Å, β= 93.58(1)°, U= 3 140.9 ų, and Z= 8. Structure solution based on 3 329 independent reflections was refined to R= 0.029. Complex (5) crystallises in space group P2₁/n with a= 11.506(3), b= 17.096(4), c= 18.115(4)Å, β= 102.32(1)°, U= 3 488.9 ų, and Z= 4. Structure solution based on 2 380 independent reflections was refined to R= 0.0517. The [ReS(SCH₂CH₂S)₂]^– and [ReO(SCH₂CH₂S)₂]^– anions exhibit square pyramidal geometry with a terminal sulphido or oxo ligand in the apical position. The S^2– ligand is derived from decomposition of the 1,2-ethanedithiolate anion with elimination of ethylene. The [Re{(SCH₂)₃CCH₃}₂]^– anion has a six-co-ordinate Re atom in a trigonal prismatic co-ordination sphere. The factors responsible for the adoption of the trigonal prismatic structure are discussed.