Structural trends in TeI₂RR′: Crystal structures and NMR spectra of TeI₂(CH₂SiMe₃)₂, TeI₂Th(CH₂SiMe₃), TeI₂Ph(CH₂SiMe₃), and TeI₂Th₂ (Th = 2‐Thienyl, C₄H₃S)

Abstract

Abstract TeI 2 (CH 2 SiMe 3 ) 2 ( 1 ), TeI 2 Th(CH 2 SiMe 3 ( 2 ), TeI 2 Ph(CH 2 SiMe 3 )( 3 ), and TeI 2 Th 2 ( 4 ) (Th = 2‐thienyl) were synthesized in excellent yields from the corresponding tellanes and I 2 . The products were characterized by 125 Te NMR spectroscopy and single crystal X‐ray crystallography. Each TeI 2 RR ′ molecule shows a trigonal bipyramidal coordination around tellurium with the iodine atoms occupying axial positions, and the organic groups and the lone pair occupying equatorial positions. The TeI bonds and the ITeI angles in 1–4 span a range of 2.8407(9)–3.0194(10) Å and 171.85(2)–175.71(2)°, respectively. The TeC bonds and CTeC angles show respective ranges of 2.100(6)–2.136(7) Å and 95.1(3)–100.9(3)°. In the solid state, the molecules show a varying degree of secondary bonding interactions. With the exception of TeI 2 ( CH 2 SiMe 3 ) 2 ( 1 ), the compounds show Te···I or I···I secondary bonding interactions leading to supramolecular assemblies. TeI 2 Ph(CH 2 SiMe 3 ) crystallizes as two polymorphs. One ( 3a ) is isomorphic with TeI 2 Th(CH 2 SiMe 3 ) ( 2 ). The other ( 3b ) shows a lattice of two alternating layers of molecules. In one layer, the molecules are linked into a two‐dimensional network by Te···I and I···I interactions whereas the second layer consists of discrete dimers. The strongest Te···I secondary bonding interactions are observed for TeI 2 Th 2 . The lattice is composed of tetramers that is reminiscent of those in γ‐ and δ‐TeI 4 and also have precedent in TeI 2 RR′ species. The structures of TeI 2 Me 2 and TeI 2 Ph 2 have been considered for comparison. The trends in 125 Te NMR chemical shifts in TeI 2 RR′ (R, R′ = Me, CH 2 SiMe 3 , Th, Ph) are also discussed. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:348–357, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20688