Synthesis and complexation of the mixed tellurium-oxygen macrocycles 1-tellura-4,7-dioxacyclononane, [9] aneO(2)Te, and 1,10-ditellura-4,7,13,16-tetraoxacyclooctadecane, [18]aneO(4)Te(2) and their selenium analogues

1,10-Ditellura-4,7,13,16-tetraoxacyclooctadecane ([18] aneO(4)Te(2)) has been synthesised in good yield (50 - 55%) from Na2Te and ClCH2CH2OCH2CH2OCH2CH2Cl in liquid ammonia, and fully characterised by NMR spectroscopy (H-1, C-13{H-1} and Te-125{H-1}) and mass spectrometry, and by the preparation of the Te(IV) derivatives [18] aneO(4)Te(2)Me(2)I(2) and [18] aneO(4)Te(2)Cl(4). A minor by-product (ca. 4%) of the preparation is 1-tellura-4,7-dioxacyclononane ([9] aneO(2)Te) which has been isolated and similarly characterised. The corresponding reaction of Na2Se with ClCH2CH2OCH2CH2OCH2CH2Cl in liquid ammonia is less satisfactory and gives variable yields of 1,10-diselena-4,7,13,16-tetraoxacyclooctadecane ([18] aneO(4)Se(2)), which is better obtained from the same reagents in ethanol solution under high dilution conditions. [18] aneO(4)Se(2) has also been thoroughly characterised spectroscopically. In these reactions the nine-membered ring 1-selena-4,7-dioxacyclononane is generally produced only in trace amounts. A range of complexes of [18] aneO(4)Te(2) (L) in which the ligand behaves only as a Te-2 donor has been synthesised, including cis-[MX2L] (M = Pd or Pt, X = Cl or Br), [RhCl2L2] Y (Y = Cl or PF6), [CuL2] BF4, [AgL2] BF4 and [Cu2L][BF4](2). The complexes have been characterised by microanalysis, multinuclear NMR spectroscopy (H-1, Te-125{H-1}, Pt-195, Cu-63), ES+ mass spectrometry, UV/visible and IR spectroscopy as appropriate. Two complexes of [9] aneO(2)Te, cis-[MCl2{[9] aneO(2)Te}(2)] (M = Pd or Pt) are also reported, together with the selenoether complex [PtCl2{[18] aneO(4)Se(2)}]. The X-ray structures of [MCl2{[18] aneO(4)Te(2)}] (M = Pt or Pd) and [ PtCl2{[18] aneO(4)Se(2)}] all reveal cis square planar coordination with no interaction between the metal and the ether oxygens.