The co-ordination chemistry of tellurium and related selenium ligands

Abstract

2-(2-pyridyl)phenyl(p-ethoxyphenyl)tellurium(II), (RR¹Te) reacts with HgC1₂ at room temperature to give white HgCl₂.RR¹Te. On setting aside, or on warming the reaction mixture a yellow material, [R¹HgCl.(RTeCl)₂] is formed. Multinuclear NMR(¹²⁵Te, ¹⁹⁹Hg, ¹H) and mass spectroscopy confirm the formulation, and confirm the ease of transfer of the p-ethoxyphenyl group (R¹) between the metal centres. The crystal structure of the yellow material consists of two discrete RTeCl molecules together with a R¹HgCl molecule. There is no dative bond formation between these species, hence the preferred description of the formation of an inclusion complex.

The reaction of RR¹Te with Copper(I) chloride in the cold gives an air sensitive yellow product Cu₃Cl₃(RR¹Te)₂(0.5CH₃CN); under reflux in air changes to the green Cu₂Cl(RR¹Te)(0.5 EtOH). By contrast, the reaction of RR¹Te with acetonitrile solution of Copper(II) salts under mild conditions affords the white materials CuCl(RR¹Te) and CuBr(RR¹Te)H₂O.

RR¹Te reacts with PdCl₂ and PtCl₂ to give materials albeit not well defined, can be seen as intermediates to the synthesis of inorganic phase of the type M_3XTe_2XCl_2X. Paramagnetism is associated with some of the palladium and platinum products. The ¹⁹⁵Pt NMR measurement in DMSO establishes the presence of six platinum species, which are assigned to Pt(IV), Pt(III) or Pt(II). The reactions show that in the presence of PdCl₂ or PtCl₂ both R and R¹ are very labile.

The reaction of RHgCl(R= 2-(2-pyridyl)phenyl) with SeX₄(X= Cl, Br) gives compounds which suggest that both Trans-metallation and redox processes are involved. By varying reaction conditions materials which appear to be intermediates in the trans-metallation process are isolated.

Potentially bidentate tellurium ligands having molecular formula RTe(CH₂)_nTeR,Lⁿ, (R= Ph,(t-Bu). C₆H₄, n = 5,10) are prepared. Palladium and Platinum complexes containing these ligands are prepared. Also complex Ph₃SnC1L(L = p-EtO.C₆H₄) is prepared.

Date of Award	May 1990
Original language	English
Supervisor	William R. McWhinnie (Supervisor)