Platinum metal ditelluroether complexes: synthesis, spectroscopic and structural studies of [M(L–L)2][PF6]2 [M = Pd or Pt, L–L = RTe(CH2)3TeR (R = Me or Ph) or C6H4(TeMe)2-o], [Rh(L–L)2Cl2]PF6, [Ru(L–L)2X2] (X = Cl, Br or I) and [Ru(L–L)2(PPh3)Cl]PF6
Abstract
The reaction of [MCl2(MeCN)2] (M = Pd or Pt) with L–L (RTe(CH2)3TeR (R = Me or Ph) or C6H4(TeMe)2-o) and TlPF6 in a 1∶2∶2 ratio in MeCN gave planar [M(L–L)2][PF6]2 which was confirmed by an X-ray crystallographic study of [Pd{meso-C6H4(TeMe)2-o}2][PF6]2. The complexes trans-[Ru(L–L)2X2] (X = Cl, Br or I) were prepared from [Ru(dmf)6][CF3SO3]3, L–L and LiX, whilst [Ru(PPh3)3Cl2], L–L and NH4PF6 gave trans-[Ru(L–L)2(PPh3)Cl]PF6. The crystal structure of [Ru{MeTe(CH2)3TeMe}2(PPh3)Cl][PF6] revealed one ditelluroether in the meso form and the other in the DL, the first time both stereoisomers have been crystallographically identified in the same compound. In contrast in trans-[Ru{PhTe(CH2)3TePh}2Cl2] both ditelluroethers are meso forms. For Pd, Pt and Ru multinuclear NMR spectroscopy (1H, 125Te-{1H}, 195Pt) showed a mixture of stereoisomeric forms in solution, and for the compounds of Pd and Pt pyramidal inversion at Te is fast on the NMR timescales at ambient temperatures. Reaction of RhCl3·3H2O, L–L and NH4PF6 gave [Rh(L–L)2Cl2]PF6 which appear to be predominantly trans isomers based upon their NMR and UV/vis spectra. Attempts to oxidise the complexes of PtII or RuII (to PtIV or RuIII) with halogens or electrochemically were unsuccessful, contrasting with the successful oxidation of analogous complexes with dithioether or diselenoether ligands.