Secondary bonding. Part 12. Aryltellurium iodides: crystal and molecular structures of cis- and trans-phenyltellurium(IV) tri-iodide and two modifications of diphenyltellurium(IV) di-iodide

Abstract

The crystal and molecular structures of cis- and trans-phenyltellurium(IV) tri-iodide and two polymorphs of diphenyltellurium(IV) di-iodide have been determined from diffractometer data : cis-(PhTeI₃)₂, orthorhombic, space group Cmc2₁, a= 19.915(5), b= 12.617(2), c= 8.867(2)Å, Z= 4, 1 267 reflections, R= 0.044; trans-(PhTeI₃)₂, orthorhombic, space group Pnnm, a= 8.911 (2), b= 11.559(2), c= 13.506(2)Å, Z= 2, 1 201 reflections, R= 0.048; α-Ph₂TeI₂, tetragonal, space group I4₁, a= 11.684(3), c= 10.196(2)Å, Z= 4, 575 reflections, R= 0.030; and β-Ph₂TeI₂, monoclinic, P2₁/c, a= 9.722(1), b= 15.627(2), c= 19.338(7)Å, β= 107.08(2), Z= 8, 3 303 reflections, R= 0.034. Both tri-iodides form iodine-bridged dimers with square-based pyramidal geometry at the tellurium. The phenyl rings are both on one side of this plane (cis), or on opposite sides (trans). No Te ⋯ I secondary bonds occur but they contain I ⋯ I interactions. Both polymorphs of the di-iodide have pseudo-trigonal bipyramidal geometry (with one vacant position), and have either one or two Te ⋯ I secondary bonds occupying the fifth and sixth positions of distorted octahedra. Te–I distances are: 2.775(2)–2.792(2) and 3.152(2)–3.285(1)Å(tri-iodide, terminal and bridge, respectively); 2.883(1)–2.959(1)Å(di-iodide).