Controlled hydrolysis of aryltellurium trichlorides using 2-pyrrolidinones: isolation and structural characterization of monomeric aryltellurium(IV) monohydroxides

Abstract

The 2-pyrrolidinone (Pyrr)-assisted hydrolysis of aryltellurium trichlorides, provided their first-step hydrolysis products as 1 : 1 molecular adducts, ArTeCl 2 OH.Pyrr (Ar = 1-C 10 H 7 , Npl, 1; 2,4,6-Me 3 C 6 H 2 , Mes, 2). The hydroxo ligand occupies an equatorial position in the y-trigonal bipyramidal geometry around Te(IV) and is involved in a strong H-bonding interaction with the amido O of the base. As NplTeBr 3 did not react with 2-pyrrolidinone under similar conditions, the bromo analogue of 1, NplTeBr 2 OH.Pyrr (3), was prepared by a metathetical reaction with NaBr. Both 1 and 2 undergo electrophilic substitution with acetone and pinacolone to afford Ar(RCOCH 2 )TeCl 2 (R = Me, t-Bu), but do not react with iodoacetic acid, suggesting that the hydroxo ligand acts as a nucleophile rather than a base. The Te-OH bond in 1 is also cleaved by CH 3 COCl to give the parent trihalide NplTeCl 3 , while reaction with BrCH 2 COBr results in NplTeBr 3 (4) as the ultimate tellurium containing product. The reaction of NplTeCl 3 with N-Methyl protected 2-pyrrolidinone (PyrrMe), under similar conditions, gave an ionic complex [(PyrrMe) 2 H] [NplTeCl 4 ] ( 5), but did not react with N-acyl protected 2-pyrrolidinone, PyrrCOCH 2 Br. However, the latter added oxidatively to elemental tellurium to give (PyrrCOCH 2 ) 2 TeBr 2 (6). In the crystal lattice of 5, discreet five-coordinate square pyramidal CTeX 4 units are present, while in the case of 4 the same units are realized via intermolecular Te … Br interactions in a one-dimensional supramolecular architecture. N-(2-pyrrolidinone)amidomethyl ligands in 6 adopt a rare, if not the first, 1,6-(C,O) mode of chelation in preference to 1,4-(C,O) mode often observed in similar Te(IV) compounds.

Isolation and molecular structures of novel organotellurium(iv) halides, oxyhalide and mixed halide

“…The compound has been isolated as 1 : 1 adduct of 1-C 10 H 7 TeCl 2 OH and 2-pyrrolidinone. 10 The isolation of supermesityltellurium hydroxide was possible due to the use of the bulky ligand and 1-C 10 H 7 TeCl 2 OH was stabilized by hydrogen bonding of the hydroxohalide with cocrystallised 2-pyrrolidinone.…”

Synthesis and structural aspects of 1-naphthyltellurium(IV) trichloride (1), bis(mesityl)tellurium(IV) dichloride (2) and bis(chlorobis(2-thiophenyl)tellurium)oxide (3)

“…In contrast to the polymeric chlorides and bromides, PhTeI 3 has been reported to exist as dimers, having either cis or trans oriented phenyl groups [9]. Recently, in the coordination chemistry of organotellurium compounds [14,15], the synthesis and the molecular structure of (a-naphthyl)TeI 3 and (a-naphthyl)TeBr 3 has been reported [16,17]. Though a large number of organotellurium trichlorides have been explored so far, only a few have been studied crystallographically [3,5,10,13,18,19] including the sterically encumbered supermesityltellurium(IV) trichloride [20].…”

“…The nearly coplanar four Cl atoms along with the Te atom {deviation from the mean plane is limited to 0.1788 Å (Cl12 atom) and 0.019 Å (Cl23 atom) in molecules I and II respectively} occupy the basal plane. Formation of similar square pyramidal, TeX 4 Y units in the solid state has been observed invariably for the anions [TeX 4 Y] À (Y = X = Cl[64] or Y = aryl group, X = Cl, Br[65]) and among the oligomeric or polymeric supramolecular motifs in the solid state of similar organotellurium trichlorides[3,10,66] as well as organotellurium tribromides[8] including the bromo analog of 1[17]. In the case of neutral organotellurium trichlorides and -tribromides formation of planar TeX 4 units takes place when the central Te atom is approached by a chloro or bromo ligand of an adjacent molecule in a direction trans to the equatorial Cl(Br)-Te bond in preference to that of the C-Te bond resulting in two quasi linear X-Te-X alignments.…”