RADICAL MECHANISM OF FORMATION OF Cu-Re AND Pb-Re COMPOSITES IN GASEOUS PHASE BY THERMAL DECOMPOSITION OF TRANS-TETRACHLORODI-μ-PROPIONATO DIRHENIUM(III)

Abstract

Reactions of individual trans-tetrachloro-di-μ-propionato dirhenium(III) thermal decomposition in dynamic inert atmosphere were investigated. Using a radical reaction of transportation in gaseous phase, Cu-Re and Pb-Re composites were obtained on a ceramic surface. Free radicals C 2 H 5 • were detected by reaction with metal Cu and Pb mirrors. Cu-Re and Pb-Re composites were studied by XRD, micro-X-ray spectral and SEM analysis. Cu-Re composites contain nano-dendrites of Cu which «grow» from a Re base and most likely have a nanotube structure. Dimensions of the nanotubes can vary from 100 nm to 1 μm.Keywords: rhenium, free radical, carboxylate, composite, mechanism, decomposition.Binuclear cluster carboxylates of rhenium(III), obtained for the fi rst time by A.S. Kotel`nikova (USSR) and Cotton (USA), are the classical complexes in chemistry of clusters [1][2][3][4]. Currently information related to the radical mechanism of thermal destruction of dirhenium(III) complexes and forming Cu-Re and Pb-Re composites is not available.The current understanding of the chemistry of rhenium carboxylates is reviewed in the book «Multiple bonds between metal atoms» [3].Investigation of thermal decomposition is very important for the determination of a detailed radical mechanism of reactions and detecting free C 2 H 5 • radical by interaction with metals like Cu and Pb. It provides an opportunity to obtain very pure Rhenium metal for a specialist industry, Re coatings and new composite materials using a chemical vapor deposition [5, 6].In this article we obtained Cu-Re and Pb-Re composites by reaction of free C 2 H 5 • radical with a Pb mirror and compact Copper. Free C 2 H 5 • radicals were formed as a result of thermal decomposition of trans-tetrachloro-di-μ-propionato dirhenium(III). RESULTS AND DISCUSSIONCeramic-based Copper-Rhenium and Lead-Rhenium composites were obtained using thermal decomposition of trans-tetrachloro-di-μ-propionato dirhenium(III) in a quartz tube (Fig. 1).During the procedure trans-tetrachloro-di-μ-propionato dirhenium(III) evaporates in a stream of inert gas at 300ºC [7] on heater 1 followed by thermal decomposition on Cu or Pb surface at 800ºC on heater 2.We carried out three experiments using different process conditions. Thermal decomposition of trans-tetrachloro-di-μ-propionato dirhenium(III) in air was studied in our previous work [6].