Cyclopalladation of telluro ether ligands: synthesis, reactivity and structural characterization

Abstract

Treatment of [PdCl2(PhCN)2] with diaryl telluride in 1 : 2 molar ratio gave mononuclear palladium complexes, trans-[PdCl2(TeR2)2] () (R = Mes () (Mes = 2,4,6-trimethylphenyl), Ph (), o-tol () (o-tol = ortho-tolyl)). Reaction of [PdCl2(TeMes2)2] with one equivalent of [PdCl2(PhCN)2] or Na2PdCl4 with TeRR' afforded chloro-bridged binuclear complexes, [Pd2(μ-Cl)2Cl2(TeRR')2] () (R/R' = Mes/Mes (); Mes/Ph (); Ph/Ph ()). A toluene-methanol solution of trans-[PdCl2(TeMes2)2] on refluxing for 30 minutes yielded a binuclear cyclopalladated complex, [Pd2(μ-Cl)2{CH2C6H2(4,6-Me2)TeMes)}2] (). When the refluxing was prolonged, a mononuclear complex cis-[PdCl2{MesTeCH2C6H2(4,6-Me2)TeMes}] () was isolated. Treatment of palladium acetate with TeMes2 afforded an acetato-bridged analogue of , [Pd2(μ-OAc)2{CH2C6H2(4,6-Me2)TeMes}2] () together with a very minor component, a tetranuclear complex, [Pd(μ-OAc)(μ-TeMes)]4 (). This reaction with unsymmetrical tellurides, MesTeR, also gave cyclopalladated complexes [Pd2(μ-OAc)2{CH2C6H2(4,6-Me2)TeR}2] (R = o-tol () and Ph ()) in which 2-methyl of the mesityl group of the telluride was exclusively metallated. The complex trans-[PdCl2(TeMes2)2] on refluxing in xylene gave palladium telluride, Pd7Te3. These complexes were characterized by elemental analyses, IR and NMR ((1)H, (13)C and (125)Te) spectroscopy. The molecular structures of trans-[PdCl2(TeMes2)2] (), [Pd2(μ-Cl)2Cl2(TeMes2)2]·2acetone (·2acetone), cis-[PdCl2{MesTeCH2C6H2(4,6-Me2)TeMes}] (), [Pd2(μ-OAc)2{CH2C6H2(4,6-Me2)TeMes)}2]·toluene (·toluene), [Pd2(μ-OAc)2{CH2C6H2(4,6-Me2)Tetol-o}2] () and [Pd(μ-OAc)(μ-TeMes)]4 () were established by single crystal X-ray diffraction analyses. The mononuclear complex was isolated in two polymorphic forms each with the trans configuration.

Reactions of Schiff Base‐Substituted Diselenides and ‐tellurides with Ni(II), Pd(II) and Pt(II) Phosphine Complexes

“…But often complex mixtures and mainly polynuclear complexes are obtained following such procedures. [24][25][26][27][28][29] Overall, the methods for the preparation of complexes with heavier chalcogenolates as ligands remain limited.…”

Coordination Polymers of Palladium Bridged by Carboxylate and Dimethylaminoalkylselenolate Ligands

“…The molecular structures of [Pd(ER′)(OAc)] n are intriguing as the overall nuclearity of the molecule is controlled by the nature of the R group. For instance, complexes containing a chalcogenolate group without any functionalized R group are tetrameric, [Pd(ER′)(OAc)] 4 (ER′=SEt, SePh, Setol‐ o , TeMes) with chelating acetate groups, while a chalcogenolate group containing internally functionalized organic groups adopt either trimeric [Pd(ECH 2 CH 2 NMe 2 )(OOCCH 3 )] 3 or dimeric [Pd(ECH 2 CH 2 CH 2 NMe 2 )(OOCCH 3 )] 2 (E=S, Se) structures with monodentate acetate ligands. The complexes [Pd(SeCH 2 CH 2 NMe 2 )(O 2 CR)] 4 (R= t Bu ( 3 ) and Ph ( 4 )) adopt a tetrameric structure despite of internally functionalized selenolate groups.…”

Emerging trends in organotellurolate chemistry derived from platinoids

“…In the case of the latter ligand system, palladium is directly coordinated to all four nitrogen atoms. 92,93 An interesting example of a halobridged complex, [ [93][94][95] These complexes were formed due to the chlorobridged cleavage reaction with the substitution of thio and seleoether through monotellurides. Usually, telluroether complexes are oriented in the cis form, which is slowly transformed to the trans isomer in solution.…”

“…190 Recently, a composition of Pd 7 Te 3 has been isolated upon reuxing the complex [PdCl 2 (TeMes 2 ) 2 ] in xylene solution. 93…”

“…However, the latter binuclear compound was converted to the mononuclear compound [PdCl 2 {MesTeCH 2 C 6 -H 2 (4,6-Me 2 )TeMes} 2 ]. The formation of the mononuclear compound mainly arose due to nucleophilic attack of mesityl tellurolate at the Pd-C bond 93. Recently, an intricate palladacycle was synthesized by the reaction between ditolyl telluride and palladium acetate in toluene solution, which yielded two complexes with theReaction of [MCl 2 (L) 2 ] (M ¼ Pd, Pt; L ¼ PhCN or COD) with a tellurium-ligated macrocyclic Schiff base.…”