Aryltellurenyl Cation [RTe(CR′₂)]⁺ Stabilized by an N‐Heterocyclic Carbene

Abstract

The reaction of the (mixed‐valent) aryltellurenyl halidesRTeTeCl2R (1), RTeTeBr2R (2) and RTeI (3, R = 2,6‐Mes2C6H3) with 1,3,4,5‐tetramethylimidazol‐2‐ylidene (CR′2) provides cationic aryltellurenyl carbene complexes of the type [RTe(CR′2)]+ A– (4, A = RTeCl2; 5, A = RTeBr2; 6, A = I). The stabilization energy and natural charge distribution of the model cation [PhTe(CR′2)]+ as well as the related σ‐donor‐stabilized cations [PhTe(PMe3)]+, [I(CR′2)]+, [I(PMe3)]+ were investigated by DFT calculations and NBO analyses.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Tellurium: a maverick among the chalcogens

“…46 Interestingly, halogenation of ditellurides with less bulky aryl substituents generates mixed-valent ditellurium dihalides ArX 2 Te IV -Te II Ar (Ar = 2,6-dimesitylphenyl) (Section 1). PPh 3 (41), NHC (42) (Scheme 18), 46,47 or via [1+4] cycloaddition with 2,3-dimethyl-1,3-butadiene. PPh 3 (41), NHC (42) (Scheme 18), 46,47 or via [1+4] cycloaddition with 2,3-dimethyl-1,3-butadiene.…”

Redox Reaction between Main‐Group Elements (Te, Sn, Bi) and N‐Heterocyclic‐Carbene‐Derived Selenium Halides: A Facile Method for the Preparation of Monomeric Halides

“…The carbene ligands stabilize abnormal oxidation states and monomeric compounds of the main‐group elements, which are otherwise unstable and oligomeric or polymeric 1–3. Recently, Beckmann et al reported the isolation of the aryltellurenyl cation stabilized by a carbene ligand 4. The reactions of the in situ generated N‐heterocyclic carbene (NHC) with elemental chalcogens afford chalcogenones ( 1 ) 5–12.…”

Nature of Bonding in Donor–Acceptor Interactions Exemplified by Complexes of N‐Heterocyclic Carbenes with 1,2,5‐Telluradiazoles

“…[7] All other relevant compoundsi ncluding [RTe(NHC)] + (4a 2.091(8) ; [8] 4c 2.117(5) ; [9] Scheme 2), [(NHC) 2 Te] 2 + (2.136(8), 2.138(5) ), [6] (NHC)Te X 2 (X = Cl, 2.103(3) ; [10] X = I, 2.106(5) [11a] ), and (NHC)[TeN(OÀBF 3 ) = C(H)(C 6 H 4 )] (2.179(9) ) [11b] possessm uch shorter CÀTe bond lengths. The CÀTe bond lengths of 1a·2 (2.343(4) )a nd 1a·3 (2.524(2)a nd 2.530(2) ;t wo independent conformers) are significantly longert han the sum of single-bond covalent radii for Te and C( 2.12 ).…”

“…Bond lengths imply that resonance form I prevails for 1a·2 and 1a·3,w hereas in [RTe(NHC)] + (4a,c) [8,9] ac loser and strongerb ond with as horter bond length implies the dominanceo fr esonance form II (Scheme 2). Bond lengths imply that resonance form I prevails for 1a·2 and 1a·3,w hereas in [RTe(NHC)] + (4a,c) [8,9] ac loser and strongerb ond with as horter bond length implies the dominanceo fr esonance form II (Scheme 2).…”

“…[8,9] Scheme3.Valence isoelectronic six-p-electron Hückel aromatics. [8,9] Scheme3.Valence isoelectronic six-p-electron Hückel aromatics.…”