The hydrolytically sensitive compounds [(SnCl₄)₂([n]aneS₄)] (n = 12, 14, 16) and [SnBr₄([n]aneS₄)] are obtained in good yield upon reaction of 2 mol. equiv. of the parent tin tetrahalide with 1 mol. equiv. of macrocycle in rigorously anhydrous CH₂Cl₂ solution. Reactions of [16]aneSe₄ with SnX₄ (X = Cl or Br) affords [SnX₄([16]aneSe₄)], while reaction of [8]aneSe₂ gives [SnCl₄([8]aneSe₂)]. The crystal structures of the three closely related complexes [SnBr₄([12]aneS₄)], [SnBr₄([14]aneS₄)]·2/3CH₂Cl₂ and [SnBr₄([16]aneS₄)] have been determined. These species represent the first examples of Sn(IV) halide adducts with neutral Group 16 ligands which adopt polymeric structures. The complexes are all chain polymers, although there is unexpected structural dependence upon the macrocycle ring-size, giving each a distinct structural form. Unusually, the coordinated S atoms in both [SnBr₄([14]aneS₄)]·2/3CH₂Cl₂ and [SnBr₄([16]aneS₄)] adopt a mutually trans arrangement. Far-IR spectra indicate that the chloro complexes all exist as cis octahedral tin(IV) species. Solution NMR spectroscopy shows that the tetrathia and tetraselena macrocyclic complexes are extensively dissociated at 295 K.