Synthesis, characterisation and coordinating properties of the small ring S2Te-donor macrocycles 9 aneS(2)Te, 11 aneS(2)Te and 12 aneS(2)Te

The reaction of Na2Te with various alpha,omega-dichlorodithioether reagents in thf-NH3(1) at ca. -78 degreesC produces moderate yields of the [1 + 1] cyclisation products, [9] aneS(2)Te (1,4-dithia-7-telluracyclononane), [11]aneS(2)Te (1,4-dithia-8-telluracycloundecane) and [12]aneS(2)Te (1,5-dithia-9-telluracyclododecane), together with polymer. These new small ring macrocycles may be purified by. ash column chromatography on silica (11-and 12-membered rings) or by recrystallisation from MeOH-thf (9-membered ring), affording yellow waxy solids. The products have been characterised by NMR (H-1, C-13{H-1} and Te-125{H-1}) and IR spectroscopy, mass spectrometry and the crystal structures of [11]aneS(2)Te and [12]aneS(2)Te have been obtained. The more stable organo-Te(IV) derivatives [n]aneS(2)TeI(2) (n = 11 or 12) and [n]aneS(2)TeMeI (n = 9, 11 or 12) are obtained in high yield as powdered solids by reaction with I-2 or MeI and these have been characterised similarly. A crystal structure of [12]aneS(2)TeI(2) has also been determined and is compared with the parent macrocycle. The synthesis of [9]aneS(2)Te is more sensitive to the precise reaction conditions than the others, and is accompanied by the formation of the ring-contraction products 1-thia-4-telluracyclohexane and 1,4-dithiane. These too have been characterised by NMR and IR spectroscopy and by mass spectrometry. The former has been unambiguously identified by X-ray crystallography and its Te(IV) methiodide derivative has been prepared for comparison. The ligating properties of the new dithiatellura-macrocycles have been investigated with a variety of transition metal species giving fac-[Mn(CO)(3)(L)]CF3SO3, cis-[MCl2(L)] (M = Pd or Pt), [Rh(Cp*)(L)](PF6)(2), [Cu(L)]BF4 and [Ag(L)]CF3SO3. Where possible, the mode of coordination has been established by spectroscopic methods, ring-size effects established and the data compared with other complexes incorporating related cyclic and acyclic ligands