Comparative assessment of weak intramolecular coordinations at tin in functionalized mono-organotin trichlorides and mono-organotrialkynyltins by multinuclear solution NMR

The intramolecular coordination behaviors of MeOOC(CH2)(2)SnCl3 and MeOOC(C H2)(2)Sn(C drop C-Ph)(3) are compared, using multinuclear NMR. including H- 1-Sn-119-HMQC spectroscopy. While MeOOC(CH2)(2)SnCl3 exhibits intramolecula r coordination to tin in solution, through the carbonyl oxygen, unlike CH3C OO(CH2)(3)SnCl3 which coordinates through the alkoxy oxygen, no firm eviden ce could be obtained for the existence of such an interaction in MeOOC(CH2) (2)Sn(C drop C-Ph)(3). This is ascribed to the lower electronegativity of a n alkynyl group, as compared to a chlorine atom, a result which is, however , in contrast with the fact that hydroxy-functionalized vinylSnPh(3) compou nds are known from literature to exhibit such weak intramolecular coordinat ions. (C) 1999 Elsevier Science S.A. All rights reserved.