Stannylenes complexes with Lewis bases

Quantum-chemical studies showed that the ability to form complexes with Lewis bases decreases on going from silylenes to stannylenes and increases in the following series of n-donor agents amines < phosphines < arsines < stibines189. This series somewhat differs from that proposed based on experimental data188. Calculations were successfully used to predict the absorption maxima shifts on complexation of silylenes with amines190. 

Data on the redox potentials of germylenes, stannylenes, plumbylenes and their complexes are scarce. In fact, only the electrochemistry of dihalogermylenes, dihalostan-nylenes and their complexes with Lewis bases as well as with chromium, molybdenum and tungsten pentacarbonyles has been studied. 

VII. VIBRATIONAL SPECTRA OF COMPLEXES OF GERMYLENES, STANNYLENES AND PLUMBYLENES WITH LEWIS BASES... 

The NMR spectra of the two-coordinate stannylenes in solution show values of Sn ranging from about 1150 (e.g., in ArSnl) to 3750 (in (Ar3Sn)Sn ), with a large anisotropy. The stannylenes behave as Lewis acids, for example, in the three- or four-coordinate complexes (e.g., 78, 79, and 80), which are formed when the molecule carries an intramolecular ligand, and as Lewis bases, particularly in complexing to transition metals (e.g., 81, 82, and 83). The dimerization of stannylenes to give distannenes can be regarded as a result of this amphoteric character (Equation (179)). 

When the stable stannylene [(Me3Si)2CH]2Sn reacts with PtCl2(PEt3)2, one unit inserts into a Pt-Cl bond, while the other acts as a Lewis base, to form the complex (R2Sn)(ClR2Sn)Pt(PEt3)Cl.107... 

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