Transition metal complexes with wide-angle dithio-, diseleno- and ditelluroethers: properties and structural systematics

Abstract

The ligands o-C₆H₄(CH₂EMe)₂ (E = S or Se) have been prepared and characterised spectroscopically. A systematic study of the coordination chemistry of these, together with the telluroether analogue, o-C₆H₄(CH₂TeMe)₂, with late transition metal centers has been undertaken. The planar complexes [MCl₂{o-C₆H₄(CH₂SMe)₂}] and [M{o-C₆H₄(CH₂EMe)₂}₂](PF₆)₂ (M = Pd or Pt; E = S or Se), the distorted octahedral [RhCl₂{o-C₆H₄(CH₂EMe)₂}₂]Y (E = S or Se: Y = PF₆; E = Te: Y = Cl) and [RuCl₂{o-C₆H₄(CH₂EMe)₂}₂] (E = S, Se or Te), the dithioether-bridged binuclear [{RuCl₂(p-cymene)}₂{μ-o-C₆H₄(CH₂SMe)₂}] and the tetrahedral [M′{o-C₆H₄(CH₂EMe)₂}₂]BF₄ (M′ = Cu or Ag; E = S, Se or Te) have been obtained and characterised by IR and multinuclear NMR spectroscopy (¹H, ⁶³Cu, ⁷⁷Se{¹H}, ¹²⁵Te{¹H} and ¹⁹⁵Pt), electrospray MS and microanalyses. Crystal structures of the parent o-C₆H₄(CH₂SMe)₂ and seven complexes are described, which show three different stereoisomeric forms for the chelated ligands, as well as the first example of a bridging coordination mode in [{RuCl₂(p-cymene)}₂{μ-o-C₆H₄(CH₂SMe)₂}]. These studies reveal the consequences of the sterically demanding o-xylyl backbone, which typically leads to unusually obtuse E–M–E chelate angles of ∼100°.