Synthesis, spectroscopic characterisation of 1,1,2,3,4,5-hexahydro-1,1-dicarboxylatotellurophenes and crystal structures of 1,1,2,3,4,5-hexahydro-1,1-di(benzoato)- and 1,1-di(4-nitrobenzoato)tellurophene

Abstract

1,1,2,3,4,5-hexahydro-1,1-dicarboxylatotellurophenes C 4H 8Te(OCOR) 2 (R=CH 2Cl, C 6H 5, 4-NO 2C 6H 4, 3,5-(NO 2) 2C 6H 3, 4-OCH 3C 6H 4) were obtained from the reactions of 1,1,2,3,4,5-hexahydro-1,1-diiodotellurophene with silver oxide and carboxylic acids or silver carboxylates. They were characterised by IR and ( 1H, 13C, 125Te)-NMR spectroscopy. The structures of C 4H 8Te(OCOC 6H 5) 2 and C 4H 8Te(4-NO 2C 6H 4OCO) 2 were established by single-crystal X-ray diffraction studies. In both cases the coordination geometry about the central Te atom can be described as pseudotrigonal bipyramidal in which two oxygen atoms of the unidentate carboxylate groups are in the axial positions, two methylene carbon atoms (attached to Te) of the C 4H 8 group and the stereochemically active electron lone pair occupy the equatorial positions. The molecules are packed in their unit cells as the weakly bridged dimers through intermolecular Te⋯O secondary bonds.