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

Abstract

Reactions of (2-choroethyl)pyrrolidine hydrochloride with ArTe − or Te 2− generated in situ by borohydride reduction of Ar 2Te 2 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 1H- and 13C{ 1H}-NMR spectroscopy. The potentially bidentate hybrid organotellurium ligand ( L 1 ) reacts with HgBr 2 and Na 2PdCl 4 to give complexes [HgBr 2· L 1 ] ( 1) and [PdCl 2· L 1 ] ( 2) respectively. The potentially tridentate ligand ( L 2 ) also forms a complex [HgBr 2· L 2 ] ( 3). All three complexes give characteristic 1H- and 13C{ 1H}-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) Å, respectively. The PdCl trans to Te (2.3915(7) Å) 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) Å) 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.