Deakin University
Browse

File(s) under permanent embargo

Amidomethylation of elemental tellurium: synthesis and solid state structures of N-substituted amidomethyltellurium(IV & II) derivatives

Version 2 2024-06-04, 03:00
Version 1 2016-10-11, 10:11
journal contribution
posted on 2024-06-04, 03:00 authored by S Misra, AKS Chauhan, P Singh, RC Srivastava, Andrew DuthieAndrew Duthie, RJ Butcher
Amidomethylation of Te(0) (elemental tellurium) as well as Te(II) (aryltellurium bromide, in situ) proceeds readily under mild conditions. It involves oxidative insertion of low valent tellurium into the C-Br bond of N-substituted alpha-bromoacetamides and provides a direct synthetic route to the stable, crystalline amidomethyltellurium(IV) dibromides, (RR'NCOCH(2))(2)TeBr(2) (RR'N = Et(2)N (1b), MePhN (2b), Me(c-Hex)N (3b), O(CH(2)CH(2))(2)N (4b)) and (Et(2)NCOCH(2))ArTeBr(2) (Ar = mesityl, 5b; 1-naphthyl, 6b). Biphasic bisulfite reduction of the dialkyltellurium dibromides afforded yellow to orange coloured amido functionalized symmetrical telluroethers, (RR'NCOCH(2))(2)Te (RR'N = Et(2)N (1), MePhN (2), Me(c-Hex)N (3), O(CH(2)CH(2))(2)N (4)), of which compound 2 was isolated as a crystalline solid. Oxidation of the new dialkyltelluroethers with dihalogens (Br(2), I(2)) or SO(2)Cl(2) afforded the corresponding amidomethyltellurium(IV) dihalides, (RR'NCOCH(2))(2)TeX(2) (RR'N = Et(2)N, X = Cl (1a), Br (1b), I (1c); RR'N = MePhN, X = Cl (2a), Br (2b), I (2c); RR'N = Me(c-Hex)N, X = Cl (3a), Br (3b), I (3c); RR'N = O(CH(2)CH(2))(2)N, X = Cl (4a), Br (4b), I (4c)) that were characterized by elemental analyses and multinuclear ((1)H, (13)C, (125)Te) NMR. Single crystal X-ray data on 1b, 1c, 2, 2b, 2c, 4b, 5b and 6b suggest that the N-substituted amidomethyl group acts as a small-bite chelating ligand, via intramolecular 1,4-Te...O coordination, towards the Te(IV) centre. Steric congestion around Te(IV) due to intramolecular secondary bonding interaction(s), reduced electrophilicity of Te(II) and the partial positive charge on N due to the resonating character of the amido group presumably prevents these atoms from participating in the intermolecular associative forces in the solid state. Instead, weak C-H...O and C-H...X H-bonding interactions take centre-stage in the self assembly.

History

Journal

Dalton transactions

Volume

39

Pagination

2637-2643

Location

London, Eng.

eISSN

1477-9234

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2010, Royal Society of Chemistry

Issue

10

Publisher

Royal Society of Chemistry