Synthesis and reactions of 1,6-bis(2-butyltellurophenyl)-2,5-diazahexa-1,5-diene and related compounds. The crystal and molecular structures of 2-(butyldichlorotelluro)benzaldehyde and bis[2-(hydroxyiminomethyl)phenyl] ditelluride

Abstract

The synthesis of 1,6-bis(2-butyltellurophenyl)-2,5-diazahexa-1,5-diene and related compounds is reported. Reaction with halogenating reagents leads to rupture of the Te–Bu bond and the isolation of new organyltellurium mono- and tri-halides stabilised via co-ordination to the imino-nitrogen atom. Reduction of the trihalides with sodium metabisulphite stops at the monohalide stage and no ditelluride is produced. Reduction of the tri- or mono-halides with hydrazine hydrate gives, depending on the molar ratio of reactants, either N-amino or N-hydroxo-compounds and in this case ditellurides are formed. Reduction of the trihalides with NaBH₄ affords a poly- or oligo-merit tritelluride stabilised by co-ordination of tellurium with the imino-nitrogen atom. By contrast the reaction of 2-(butyltelluro) benzaldehyde with chlorinating agents gives 2-(butyldichloro-telluro) benzaldehyde in which the Te–Bu linkage survives intact. Spectroscopic data, particularly ¹³C n.m.r., are presented and briefly discussed. The crystal and molecular structures of bis[2-(hydroxyiminomethyl)phenyl] ditelluride and of 2-(butyldichlorotelluro) benzaldehyde have been determined. The ditelluride has Te–Te 2.746(1)Å with C–Te–Te angles of 100.0(2) and 100.3(2)°; Te–N distances of 2.822(5)Å and 2.876(5)Å indicate a weak interaction. In the benzaldehyde derivative the tellurium is bonded to two carbon atoms and two chlorine atoms; a weak Te ⋯ O interaction [2.839(4)Å(mean for two independent molecules)] and a lone pair of electrons complete a distorted pseudo-octahedral co-ordination. The molecule, apart from the two axial chlorine atoms, is essentially planar.