Zwei Extreme in der Zinnchemie: Ein nichtbindender Sn–Sn‐Abstand von 285 pm und eine 119 Sn‐NMR‐Verschiebung δ = 3301 in metallorganischen Derivaten von Sn(0)

Two Extremes in Tin Chemistry: A Non‐bonding Sn–Sn Distance of 285 pm and a 119 Sn‐NMR Shift δ = 3301 in Organome‐tallic Derivatives of Sn(0) The reaction of Na[{Cp'(CO) 2 Mn} 2 H] with SnCl 2 , which produces the inidene compound [Cp'(CO) 2 Mn \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ {\rm C}\ddot - {\rm C} $\end{document} Sn(Cl) \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ {\rm C}\ddot - {\rm C} $\end{document} Mn‐(CO) 2 Cp'] − under standard workup procedures, results in the formation of [{Cp'(CO) 2 MnSn} 2 {μ 2 ‐Mn(CO) 2 Cp'} 2 {μ 2 ‐Cl}] − ( 1 ) when quenched with unpolar solvents. While, formally, 1 contains tin in its oxidation state zero, it may be conceived as composed of an Sn 2− 2 entity, which is linearly end‐on coordinated to two Cp'(CO) 2 Mn 16‐electron species; in addition the tin centers are bridged by two μ 2 ‐Mn(CO) 2 Cp' moieties and a μ 2 ‐Cl function. The resulting connectivity Sn 2 {μ 2 ‐Mn(CO) 2 Cp'} 2 {μ 2 ‐Cl} thus corresponds to a [1.1.1]propellane scaffolding. While there is no obvious need for a tin‐tin bond in this propellane‐type cage, a short Sn–Sn contact of only 285 pm is observed. While the 119 Sn‐NMR signal of 1 could not be recorded, the peculiar bonding in this type of compounds is generally mirrored in their unconventional 119 Sn‐NMR shift whereever signals can be observed: it is found that [{Cp*(CO) 2 Mn} 3 (μ 3 ‐Sn)], which contains trigonally planar‐coordinated μ 3 ‐Sn as a naked ligand atom, has its 119 Sn‐NMR resonance at δ = 3301 well beyond the known range of 119 Sn‐NMR shifts. This finding is interpreted in terms of a relatively week Sn pπ ‐Mn dπ π bonding which leads to low‐energy unoccupied molecular orbitals as the prerequisit for a large paramagnetic contribution to the NMR shift.