Electrochemical and Reactivity Studies of N→Sn Coordinated Distannynes

Abstract

Studies are focused on the redox potentials of N→Sn coordinated distannnynes {L Sn} (L =1, L =2 and L =3, in which L is [C H -2,6-(Me NCH ) ] , L is [C H -2,4-tBu -6-(Et NCH )] and L is [C H -2,4-tBu -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 [{L Sn} ⋅Fe(CO) ] (4) and [{L Sn} ⋅Fe(CO) ] (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 L or Sn →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 {(L SnO)(L )Sn(μ-O)} (6) as a consequence of the instability of the expected {L Sn⋅TEMPO} complex. To support this proposed mechanism, the N→Ge coordinated digermyne {L Ge} (7) was prepared. The reaction of 7 with TEMPO provided the expected complex {L Ge⋅TEMPO} (8).

Ambiphilic Nature of Dipyrrolylpyridine-Supported Divalent Germanium and Tin Compounds

“…Notably, these ligands were found to effectively stabilize low-valent species. In this context, singly bonded Sn­(I) species (distannynes) supported by pincer-type ligands (for example, N,C,N-coordinated 2,6-(Me 2 NCH 2 ) 2 C 6 H 3 – , and {2,6- i Pr 2 C 6 H 3 NC­(CH 3 )} 2 C 6 H 3 – , as well as O,C,O-coordinated 4- t Bu-2,6-[P­(O)­(O- i Pr) 2 ] 2 C 6 H 2 – (L OCO ) ligands, as shown by Jurkschat, Roesky, Stalke, and Jambor) exhibit new types of structure and reactivity patterns, in contrast with those of the multiple-bonded distannynes discovered by Power and co-workers. − In addition, we previously reported the synthesis of low-valent, pincer ligand supported tritin complexes [(dpp Ph Sn) 3 ] + X – (dpp Ph = 2,5-di­( o -pyridyl)-3,4-diphenylpyrrolate; X = Cl, OTf, PF 6 , and AlCl 4 ), which contain two Sn–Sn linkages nearly perpendicular to the dpp Ph ligand planes . This demonstrates that the occupation of p x and p y orbitals of Sn centers by the planar pincer dpp Ph ligand allows further bonding interactions along the z direction (using the p z orbitals of Sn).…”

Coordination of a Central Atom by Multiple Intramolecular Pnicogen Bonds

“…Indeed, the literature provides ample evidence that noncovalent bonds of this sort occur not only between pairs of molecules but also as intramolecular interactions within the context of a single molecule. The most numerous to date are chalcogen bonds, − but there are also many examples of tetrel − and halogen bonds as well. − Pnicogen bonds, too, are commonly observed as intramolecular contacts. − …”

The Role of Monoanionic Aryl Pincer Ligands in the Stabilization of Group 14 Metallylenes

“…[42] Derivative 44 in reaction with diorgano disulfides formed the corresponding organotin(II) thio derivatives. [44] The redox potential of the tin atom in the diorganodistannyne L I SnSnL I [L I = 2,6-(R2NCH2)2C6H3, R = Me], [45] as well as the reduction ability of these type of distannynes were also studied. [46] The coordination ability of chlorostannylene 27 was tested towards different transition metal complexes, as show in Scheme 10.…”