An investigation of the structures, properties and possible applications of complexes of metals with organotellurium compounds

Abstract

Organic telluridecomplex forming ability was investigated. It is
found that tellurides form quite stable complexes with metals of
class (b) or softish character. Copper(I), rhodium(III) and
rhodium(I) complexes with diaryltellurides were synthesised.
Their structure, properties and uses were investigated with the
help of various physical techniques.

Copper(1) halides and tellurides were found to form complexes
with definite compositions irrespective of the ratio of metal:
ligand used. A 2:1 ligand to metal ratio was preferentially
formed among the copper(I) complexes. The structures of these
copper(I) compounds were found to range from tetrahedral, fourcoordinated
copper(I) halogen bridged dimers, trigonal planar and
three coordinated copper(I) halogen bridged dimers. The copperhalogen
stretching vibrations v(Cu - X); (X = Cl, Br, I) were found
to be rather low compared with the available literature values.

Rhodium(III) halides with tellurides were found to form
complexes of the type ML 3X33 (L = diaryltelluride; X = Cl, Br)
to which a configuration was assigned with the aid of far infra-red
and n.m.r. spectroscopy. mer RhL 4X, was found to form in good
yield under dinitrogen. The preparation carried our under air
yielded the complex fac RhL 3X. in lower yield. Reactions using
[Rh(PhaTe) C1 3] as a synthetic intermediate in preparing complexes of the type [Rh(Ph,Te) (chelate )C1,]; (chelate = 2,2'bipyridyl,
1,10'phenanthroline, di-2-pyridylketone, di-2-pyridylamine) were
carried out. A rhodium(I) complex with telluride was found to be
stable only in the presence of CO; a complex formulated as
-[Rh(PhTe),(CO)C1] was synthesised. Reactions using telluride to
stabilise rhodium(I) compounds in the presence of ethanolic KOH
and borohydride were unsuccessful.

Reactions to test the complex Rh(PhoTe) C1, as a homogeneous
hydrogenation catalyst were carried out. It was found that
Rh (PhoTe) C1, did not catalyse the homogeneous hydrogenation
reaction contrary to the complexes (RhL.C14); (L = Et S, (PhcH.),S )
which are known to be active.

The role of di-2-pyridylketone as ligand was investigated.
Some complexes of cobalt, iron, nickel and copper with di-2-
pyridylketone were synthesised and characterised by various
techniques. An explanation for the anomolous magnetic behaviour
of cobalt complex reported by a previous worker is given. Tris
complexes of di-2-pyridylketone were found to exist. The ligand
field parameters of some complexes are given, and di-2-pyridylketone
was found to be a weak field ligand.

It was noted that under some circumstances the carbonyl group
of the ligand became readily aquated or alcoholated. The ease of
formation of these acetal or hemicetal deriviatives is discussed and it is concluded that, contrary to the previous suggestion, steric
strain within the carbonyl ligand need not be a major cause.

All complexes prepared are discussed in terms of their
analytical data and spectra, including in the case of iron(II) and
iron(III) complexes their 57 Fe Mössbauer spectra. In one case
good evidence for an(N,0)mode of coordination for di-2-pyridylketone
was found.

Date of Award	1973
Original language	English