ISSN:
0009-2940
Schlagwort(e):
Tin complexes
;
Transition metal complexes
;
NMR, 119Sn
;
Sn(0) compounds
;
Chemistry
;
Inorganic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Two Extremes in Tin Chemistry: A Non-bonding Sn-Sn Distance of 285 pm and a 119Sn-NMR Shift δ = 3301 in Organome-tallic Derivatives of Sn(0)The reaction of Na[{Cp'(CO)2Mn}2H] with SnCl2, which produces the inidene compound [Cp'(CO)2Mn\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)2Cp']- under standard workup procedures, results in the formation of [{Cp'(CO)2MnSn}2{μ2-Mn(CO)2Cp'}2{μ2-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 Sn2-2 entity, which is linearly end-on coordinated to two Cp'(CO)2Mn 16-electron species; in addition the tin centers are bridged by two μ2-Mn(CO)2Cp' moieties and a μ2-Cl function. The resulting connectivity Sn2{μ2-Mn(CO)2Cp'}2{μ2-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 119Sn-NMR signal of 1 could not be recorded, the peculiar bonding in this type of compounds is generally mirrored in their unconventional 119Sn-NMR shift whereever signals can be observed: it is found that [{Cp*(CO)2Mn}3(μ3-Sn)], which contains trigonally planar-coordinated μ3-Sn as a naked ligand atom, has its 119Sn-NMR resonance at δ = 3301 well beyond the known range of 119Sn-NMR shifts. This finding is interpreted in terms of a relatively week Snpπ-Mndπ π bonding which leads to low-energy unoccupied molecular orbitals as the prerequisit for a large paramagnetic contribution to the NMR shift.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/cber.19951280217
Permalink
