An Investigation of the Structures, Properties and Possible Applications of Complexes of Metals with Organotellurium Compounds

Abstract

Organic telluride complex 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) andrhodium (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, four coordinated copper (I) halogen bridged dimers, trigonal planar and three coordinated copper(I) halogen bridged dimers. The copper- halogen 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 3X3; (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 3X3 was found to form in good yield under dinitrogen. The preparation carried our under air yielded the complex fac RhL 3X3. in lower yield. Reactions using[Rh(Ph2Te) 3C13] as a synthetic intermediate in preparing complexes of the type [Rh(Ph2Te) (chelate )C13]; (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(Ph2Te)2(CO)C1] was synthesised. Reactions using telluride tostabilise rhodium(I) compounds in the presence of ethanolic KOH and borohydride were unsuccessful. Reactions to test the complex Rh(Ph2Te) 3C13, as a homogeneous hydrogenation catalyst were carried out. It was found that Rh (Ph2Te) 3C12, did not catalyse the homogeneous hydrogenation reaction contrary to the complexes (RhL3C13); (L = Et 2S, (PhcH2)2S )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 behaviourof cobalt complex reported by a previous worker is given. Tris complexes of di-2-pyridylketone were found to exist. The ligandfield 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 offormation of these acetal or hemicetal deriviatives is discussed and it is concluded that, contrary to the previous suggestion, stericstrain within the carbonyl ligand need not be a major cause. All complexes prepared are discussed in terms of theiranalytical data and spectra, including in the case of iron(II) andiron(III) complexes their 57 Fe Mössbauer spectra. In one case good evidence for an(N,0)mode of coordination for di-2-pyridylketonewas found.