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

Abstract

AbstractTeI2(CH2SiMe3)2(1), TeI2Th(CH2SiMe3 (2), TeI2Ph(CH2SiMe3)(3), and TeI2Th2(4) (Th = 2‐thienyl) were synthesized in excellent yields from the corresponding tellanes and I2. The products were characterized by 125Te NMR spectroscopy and single crystal X‐ray crystallography. Each TeI2RR′ 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 TeI2(CH2SiMe3)2 (1), the compounds show Te···I or I···I secondary bonding interactions leading to supramolecular assemblies. TeI2Ph(CH2SiMe3) crystallizes as two polymorphs. One (3a) is isomorphic with TeI2Th(CH2SiMe3) (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 TeI2Th2. The lattice is composed of tetramers that is reminiscent of those in γ‐ and δ‐TeI4 and also have precedent in TeI2RR′ species. The structures of TeI2Me2 and TeI2Ph2 have been considered for comparison. The trends in 125Te NMR chemical shifts in TeI2RR′ (R, R′ = Me, CH2SiMe3, 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