Hybrid (Te, N) and (N, Te, N) ligands having pyrrolidine ring and their palladium(II) and mercury(II) complexes: synthesis and crystal structures

Singh, G., Singh, A. K., Sharma, P., Drake, J. E., Hursthouse, M. B. and Light, M. E. (2003) Hybrid (Te, N) and (N, Te, N) ligands having pyrrolidine ring and their palladium(II) and mercury(II) complexes: synthesis and crystal structures. Journal of Organometallic Chemistry, 688 (1-2), 20-26. (doi:10.1016/j.jorganchem.2003.08.024).

Abstract

Reactions of (2-choroethyl)pyrrolidine hydrochloride with ArTe- or Te2- generated in situ by borohydride reduction of Ar2Te2 or elemental tellurium give N-{2-(4-methoxyphenyltelluro)ethyl}pyrrolidine (L-1) or bis{2-(pyrrolidine-N-yl)ethyl} telluride (L-2), respectively, as viscous liquids, which are characterized by H-1- and C-13 {H-1}-NMR spectroscopy. The potentially bidentate hybrid organotellurium ligand (L-1) reacts with HgBr2 and Na2PdCl4 to give complexes [HgBr2.L-1] (1) and [PdCl2.L-1] (2) respectively. The potentially tridentate ligand (L-2) also forms a complex [HgBr2.L-2] (3). All three complexes give characteristic H-1- and C-13{H-1}-NMR spectra, although the deshielding of carbon atoms linked to Te/N as well as protons attached to them is small in the case of both Hg complexes. The single crystal structures of 1-3 have been solved. In 1 and 2 the ligand L-1 coordinates via Te and N both with metal indicating that the pyrrolidine N has good ligating strength. The Pd-Te and Hg-Te bond lengths are 2.4781(3) and 2.747(1) Angstrom, respectively. The Pd-Cl trans to Te (2.3915(7) Angstrom) is longer than other Pd-Cl bond length. There are two independent molecules in the asymmetric unit of 3 that have essentially the same bidentate molecular structures. There is no evidence of significant intermolecular Hg-Br bonding. The Hg-Te bond in 3 (ave. 2.686(2) Angstrom) is shorter than in 1. The potentially tridentate ligand L 2 in complex 3 coordinates only as a bidentate donor. The molecular weights of 1 and 2 are close to double the formula weight indicating strong molecular association in solution. Te-C(alkyl) is somewhat longer than Te-C(aryl) for complexes 1 and 2.

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Contributors

Author: M. E. Light

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