Mercapto derivatives of triorganotin Y,C,Y-pincer complexes: Role of Y,C,Y-chelating ligands in a new coordination mode of organotin compounds

Abstract

We report the use of triorganotin fragments R 2L 1-2Sn containing N,C,N and O,C,O-ligands L 1-2(L 1 = C 6H 3(Me 2NCH 2) 2-2,6 −, L 2 = C 6H 3( t BuOCH 2) 2-2,6 −) on stabilization of both thiol-form in R 2L 1-2Sn-2-SPy (2-SPy = pyridine-2-thiolate) and thione-form in R 2L 1-2Sn(mimt) (mimt = 1-methylimidazole-2-thiolate) of the polar groups. Treatment of ionic organotin compounds [Me 2L 1Sn] +[Cl] − ( 1) and [Ph 2L 2Sn] +[OTf] − ( 2) with appropriate sodium salts Na-2-SPy and Na(mimt) resulted in the isolation of Me 2L 1Sn-2-SPy ( 3), Ph 2L 2Sn-2-SPy ( 4), Me 2L 1Sn(mimt) ( 5), Ph 2L 2Sn(mimt) ( 6). While polar group 2-SPy exists in its thiol-tautomeric form in compounds 3 and 4, the second polar group (mimt) has been stabilized as the thione-tautomeric form by triorganotin fragments R 2L 1-2Sn in compounds 5 and 6. The products were characterized by 1H, 13C and 119Sn NMR and IR spectroscopy, ESI/MS, elemental analyses and structures of 3, 6 were determined by X-ray diffraction study. The reactivity of compound 4 containing non-coordinated nitrogen atom of 2-SPy polar group towards CuCl and AgNO 3 is also reported. The reactions led to isolation of organotin compounds Ph 2L 2SnCl ( 7) and Ph 2L 2SnNO 3 ( 8) as the result of polar group transfer. The mechanism of this reaction has been investigated and compounds Ph 3Sn-2-SPy ( 9) and Ph 2L 2Sn-4-SPy ( 10) (4-SPy = pyridine-4-thiolate) have been prepared for this purpose.