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A Comparative PMR study of Exchange reactions in organo- Mercury, -TIN and -LEAD derivatives of some thiols

1974; Elsevier BV; Volume: 77; Issue: 2 Linguagem: Inglês

10.1016/s0022-328x(00)81319-4

1872-8561

D. N. Kravtsov, Аlexander S. Peregudov, E. M. Rokhlina, L. A. Fedorov,

Organometallic Compounds Synthesis and Characterization

Abstract Metal—proton and metal—metal exchange reactions have been studied by PMR for thiophenol, 2-methylthiophenol, 2,6-dimethylthiophenol, benzyl mercaptan and their C 6 H 5 HG, (C 6 H 5 ) 3 Sn and (C 6 H 5 ) 3 Pb derivatives in chlorobenzene and pyridine solutions. In chlorobenzene the metal—metal exchange has been found to proceed in many cases at a greater rate than the metal—proton type, the exchange mobility of hydrogen and organometallic groups in chlorobenzene increasing in the order (C 6 H 5 ) 3 Sn 6 H 5 ) 3 Pb 6 H 5 Hg. In the case of the (C 6 H 5 ) 3 Sn and (C 6 H 5 ) 3 Pb groups, pyridine accelerates the metal—proton exchange to a greater extent than the metal—metal exchange. The influence of various factors on the exchange reactions has been studied Analysis of the experimental findings and literature data has led to the conclusion that most probably the mechanism of the exchange reactions involves an associative pathway, the ease of exchange being mainly determined by the ability of the migrating group to form a cyclic transition state with delocalized bonds. The data on the exchange equilibria of the organometallic derivatives of 2-methylthiophenol and 2,6-dimethylthiophenol with thiophenol and its derivatives demonstrate that the C 6 H 5 HgS, (C 6 H 5 ) 3 SnS and (C 6 H 5 ) 3 PbS groups have equal steric requirements when involved in non-bonded interactions with o -methyl substituents.