Reactivity Studies on an Intramolecularly Coordinated Organotin(IV) Carbonate

The reactivity of the intramolecularly coordinated organotin(IV) carbonate L(Ph)Sn(CO3) (1), where L stands for an N,C,N-chelating ligand, 2,6-(Me2NCH2)(2)C6H3, was studied. The treatment of 1 with ferrocene-based carboxylic acids RCOOH afforded the organotin(IV) dicarboxylates LPhSn(O2CR)(2), where R is ferrocenyl (2), 2-ferrocenylethyl (3), and [(1E)-2-ferrocenyl] ethenyl (4). Surprisingly, compounds 2-4 are sensitive to moisture and easily hydrolyze with condensation into the corresponding hexameric organotin oxo clusters (PhSnO)(6)(O2CR)(6) (R = ferrocenyl (5), 2-ferrocenylethyl (6), and [(1E)-2-ferrocenyl]ethenyl (7)) possessing a Sn6O6 drumlike core. On the other hand, treatment of 1 with non-carboxylic acids such as HOTf, H3BO3, H3PO3, and t-BuPO3H2 afforded the triflate salt of a cationic organotin(IV) hydroxide {[LPh(H2O)Sn(mu-OH)](2)}(OTf)(2) (8), stannaboroxine LPhSnB2O3(OH)(2) (9), and organotin(IV) phosphite [L(Ph)Sn(HPO3)](2) (10) and phosphonate {[L(Ph)Sn](2)(mu-OH2)(mu-t-BuPO3)(2)} (11), respectively. Compounds 2-11 were characterized by elemental analysis and multinuclear NMR spectroscopy, and the molecular structures of compounds 6 and 9-11 were determined by single-crystal X-ray diffraction analysis. In addition, compounds 2-7 bearing redox-active ferrocenyl groups were studied by cyclic voltammetry.