Electrochemical and Reactivity Studies of N→Sn Coordinated Distannynes

• Published in: Chemistry : a European journal 2018-01, Vol.24 (5), p.1104-1111
• Main Authors: Novák, Miroslav, Mikysek, Tomáš, Růžička, Aleš, Dostál, Libor, Jambor, Roman
• Format: Article
• Language: English
• Subjects: Chemistry; Coordination compounds; coordination modes; Electrochemistry; Group 14 elements; Heavy metals; Ligands; Organotin; Oxidation; Stability; Tin; Transition metals; Valence
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201703960

Studies are focused on the redox potentials of N→Sn coordinated distannnynes {L1–3Sn}2 (L1=1, L2=2 and L3=3, in which L1 is [C6H3‐2,6‐(Me2NCH2)2]−, L2 is [C6H2‐2,4‐tBu2‐6‐(Et2NCH2)]− and L3 is [C6H2‐2,4‐tBu2‐6‐(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 [{L1Sn}2⋅Fe(CO)4] (4) and [{L2Sn}2⋅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 SnI→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 {(L2SnO)(L2)Sn(μ‐O)}2 (6) as a consequence of the instability of the expected {L2Sn⋅TEMPO} complex. To support this proposed mechanism, the N→Ge coordinated digermyne {L2Ge}2 (7) was prepared. The reaction of 7 with TEMPO provided the expected complex {L2Ge⋅TEMPO} (8). Focus on tin: Different N→Sn coordinated distannnynes, {L1–3Sn}2, containing tin atoms in oxidation state +I were prepared and used as ligands for transition metals to provide complexes, [{L1−2Sn}2⋅Fe(CO)4] (see figure). Cyclic voltammetry measurements revealed the oxidation potentials of tin atoms and the influence of N→SnI and SnI→Fe coordination.