Electrophilic substitution reactions of 2-acetylpyridine, 2-acetylpyrrole & cyclohexanone: Isolation and molecular structures of novel organotellurium(IV) chlorides

Chloro analogs of novel organotellurium(IV) compounds (1a, 2Aa, 2Ba, 3Aa & 3Ba) have been synthesized by using electrophilic substitution reactions. The 2-pyridoylmethyltellurium(IV) trichloride, PyCOCH2TeCl3; 1a (Py = 2-C5H4N, 1) has been prepared by the condensation reaction between the parent methyl ketone (PyCOCH3) and TeCl4. Aryl(2-pyrrolylmethyl)tellurium(IV) dichlorides, Ar(PyrrCOCH2)TeCl2; 2Aa, 2Ba (Pyrr = 2-C4H4N, 2; Ar = 1-C10H7, Npl, A; 2,4,6-Me3C6H2, Mes, B) and aryl(2-oxocyclohexyl)tellurium(IV) dichlorides, Ar(Cyl)TeCl2; 3Aa, 3Ba (Cyl = 2-C6H9O, 3) have been prepared by electrophilic substitution reaction of NplTeCl3 or MesTeCl3 with 2-acetylpyrrole and cyclohexanone respectively. Formation of tellurium(IV) trichloride (PyCOCH2TeCl3, 1a) corresponds to a category of compound which are rarely obtained using this methodology. Structural aspects of Te(IV) compounds 1a, 2Ba and 3Ba have been studied using single crystal X-ray diffraction technique. Crystallographic studies of 1a has indicated a preference of the 2-pyridoylmethyl moiety for the small-bite (C, N) chelation resulting in the 1,5 Te⋯N hypervalent interaction while in PyrrCOCH2MesTeCl2, 2Ba; 2-pyrrolylmethyl moiety (C, O) chelation over less strained (C, N) coordination is preferred. In 3Ba, 1,4 Te⋯O intramolecular secondary bonding interaction (SBI) has appeared.

New organotellurium(IV) derivatives, PyCOCH2TeCl3, Ar(PyrrCOCH2)TeCl2 and Ar(Cyl)TeCl2 were prepared from electrophilic substitution reaction of ketone with TeCl4 and ArTeCl3. Two independent molecules of asymmetric unit in crystal lattice of PyCOCH2TeCl3, formed a centrosymmetric dimer via Te⋯Cl interaction which further interlinked via C–H⋯O interactions to form a 1–D supramolecular array.Figure optionsDownload as PowerPoint slideHighlights
► PyCOCH2TeCl3 was synthesized from electrophilic reaction of PyCOCH3 and TeCl4.
► Ar(PyrrCOCH2)TeCl2 and Ar(Cyl)TeCl2 were synthesized using ArTeCl3.
► The newly synthesized compounds were characterized from 1H, 13C, 125Te NMR techniques.
► Compounds 1a, 2Ba and 3Ba were also crystallographically studied.
► 1,5-Te⋯N intramolecular interaction are preferred in 1a over the commonly observed 1,4-Te⋯O.