S. Misra, A. Chauhan, R. Srivastava
Oct 3, 2011
Citations
0
Influential Citations
5
Citations
Journal
RSC Advances
Abstract
The 2-pyrrolidinone (Pyrr)-assisted hydrolysis of aryltellurium trichlorides, provided their first-step hydrolysis products as 1 : 1 molecular adducts, ArTeCl2OH.Pyrr (Ar = 1-C10H7, Npl, 1; 2,4,6-Me3C6H2, Mes, 2). The hydroxo ligand occupies an equatorial position in the ψ-trigonal bipyramidal geometry around Te(IV) and is involved in a strong H-bonding interaction with the amido O of the base. As NplTeBr3 did not react with 2-pyrrolidinone under similar conditions, the bromo analogue of 1, NplTeBr2OH.Pyrr (3), was prepared by a metathetical reaction with NaBr. Both 1 and 2 undergo electrophilic substitution with acetone and pinacolone to afford Ar(RCOCH2)TeCl2 (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 CH3COCl to give the parent trihalide NplTeCl3, while reaction with BrCH2COBr results in NplTeBr3 (4) as the ultimate tellurium containing product. The reaction of NplTeCl3 with N-Methyl protected 2-pyrrolidinone (PyrrMe), under similar conditions, gave an ionic complex [(PyrrMe)2H] [NplTeCl4] (5), but did not react with N-acyl protected 2-pyrrolidinone, PyrrCOCH2Br. However, the latter added oxidatively to elemental tellurium to give (PyrrCOCH2)2TeBr2 (6). In the crystal lattice of 5, discreet five-coordinate square pyramidal CTeX4 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.