Electrochemical and Reactivity Studies of N -> Sn Coordinated Distannynes

Studies are focused on the redox potentials of N -> Sn coordinated distannnynes {L1-3Sn}(2) (L-1 = 1, L-2 = 2 and L-3 = 3, in which L-1 is [C6H3-2,6-(Me2NCH2)(2)](-), L-2 is [C6H2-2,4-tBu(2)-6-(Et2NCH2)](-) and L-3 is [C6H2-2,4-tBu(2)-6-(DippN=CH)](-); Dipp = 2,6-diisopropylphenyl), containing the tin atom in oxidation state + I. Distannynes 1-3 were used as ligands for transition metals, and complexes [{(LSn)-Sn-1}(2)center dot Fe(CO)(4)] (4) and [{(LSn)-Sn-2}(2)center dot Fe(CO)(4)] (5) were prepared. The set of N -> Sn coordinated distannynes 1-5 was studied by cyclic voltammetry measurements and the oxidation potentials of tin atoms in 1-5 were determined. The redox potentials are influenced by either ligands L1-3 or Sn-I -> Fe coordination. Oxidation reactions of 1-3 were also studied. The reaction of 2 with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) provided mixed organotin oxide {((LSnO)-Sn-2)(L-2) Sn(mu-O)}(2) (6) as a consequence of the instability of the expected {(LSn)-Sn-2 center dot TEMPO} complex. To support this proposed mechanism, the N -> Ge coordinated digermyne {(LGe)-Ge-2}(2) (7) was prepared. The reaction of 7 with TEMPO provided the expected complex {(LGe)-Ge-2 center dot TEMPO} (8).