Isolation of Homoleptic Dicationic Tellurium and Monocationic Bismuth Analogues of Non-N-Heterocyclic Carbene Derivatives

The first examples of Te analogues of non-N-heterocyclic carbene (non-NHC) derivatives, [(ppy)2Te]·2ClO4, [4]·2ClO4, and­[(ppy)2Te]·2OTf, [5]·2OTf [where ppy = 2-(2′-pyridyl)­phenyl and Tf = O2SCF3] are reported by the metathesis reaction of diorganoiodotelluronium­(IV) cation, [(ppy)2TeI]·I3, [3]·I3, with AgClO4 and AgOTf, respectively. The metathesis reaction of ppyTeCl3, 6, with an excess of AgClO4 resulted in the isolation of [ppyTe­(μ-O)]2·2ClO4, [8]·2ClO4. The reaction of triorganotelluronium­(IV) cation [(ppy)3Te]·Br, [10]­Br, with K2PdCl4 afforded [(ppy)2TeCl]·[(ppy)­PdCl2], 11. The generality of the “ppy” group on stabilizing other main-group non-NHC analogues has been further established by synthesizing the second example of a Bi analogue of a non-NHC derivative, namely, bismuthenium ion, [(ppy)2Bi]·Cl, [12]·Cl, using the same aryl group. All of the synthesized compounds are unambiguously authenticated by single-crystal X-ray diffraction studies. DFT calculations [natural bond orbital (NBO), atoms in molecules (AIM), and electron localization function (ELF)] indicate that the stability of the non-NHC carbenoids relies on the σ-hole participation of the Te/Bi atom with the strong intramolecular coordination ability of the pyridyl N atom of the aryl substituent.