1,4,7‐Trithiacyclononane as a Tridentate Ligand for Complexation of Heavy‐Metal Ions: Synthesis and Complexation Studies of Mesocyclic and Macrocyclic Polythioethers IV

Abstract

Bis octahedral complexes of 1,4,7‐trithiacyclononane (9‐ane‐S3) with Group 12 metal ions Zn(II), Cd(II), and Hg(II), as well as Pb(II), have been prepared. Two equivalents of 9‐ane‐S3 react with Zn(BF4)2·6H2O, Cd(ClO4)2·6H2O, Hg(ClO4)2·3H2O, and Pb(ClO4)2. 3H2O, respectively, to give stable crystalline complexes of the formula [M(9‐ane‐S3)2]2+ 2X−. Single‐crystal X‐ray structures of the zinc and mercury complexes have been determined. The zinc complex crystallizes in the orthorhombic space group Pbca with four molecules per unit cell (a = 9.219(3) Å, b = 15.400(5) Å, and c = 19.965(10)Å; R = 7.6%) whereas the mercury complex crystallizes in the monoclinic space group P21/c with two molecules per unit cell (a = 10.400(3) Å, b = 15.190(4) Å, c = 9.533(3) Å, and p = 99.09(3)°; R = 5.2%). In each structure, the metal atom is located on a crystallographic center of inversion and is octahedrally surrounded by six sulfur atoms provided by the two facially coordinating tridentate ligands. Reaction of 9‐ane‐S3 with RuCl3·xH2O displaces chloride ions with concomitant reduction of Ru(III) to Ru(II), giving the octahedral thioether complex, [Ru(9‐ane‐S3)2]Cl2·4H2O. Reaction of the ligand with RhCl3, on the other hand, gives (9‐ane‐S3)RhCl3. A single‐crystal X‐ray structure determination has been done on the Ru(II) complex (triclinic space group P1̅; a = 7.652(1) Å, b = 8.946(1) Å, c = 9.042(1) Å, α = 93.43(1)°, β = 103.43(1)°, and γ = 107.79(1)°; R = 2.8%) and this complex is also octahedral with the metal center at an inversion center.