Germylenes complexes with Lewis bases

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... 

Intramolecular Lewis base complexation of the germanium atom also did not appear to be a valuable alternative to overcome the lability of these elusive intermediates, since the germanones expected from oxidation of the base-stabilized germylenes 140131 (with Me3NO) and 141132 (with 02, DMSO, or pyridine oxide) either rearrange as already mentioned [Section VI,A,4, Eq. (33)]131 or dimerize to digermadioxetane 160132 [Eq. (35)]. 

Reaction of germylenes with elemental chalcogens (sulfur, selenium, tellurium) also allowed the synthesis of stable >Ge = E species. This was first exemplified by the isolation of terminal chalcogenido complexes of germanium 170152 and 171-173153 (Scheme 34). Stabilization in these cases is achieved by intramolecular complexation of the metal atom by Lewis bases. 

Complexation of germylenes with such weak Lewis bases as aromatics was suggested119. The authors observed hypsochromic shifts of the absorption maximum of Me2Ge if its precursors contained aromatic substituents. Moreover, the absorption maximum of... 

Germylenes form Lewis base complexes with the lone pair of electrons they also form Lewis acid complexes with reagents possessing lone pairs of electrons . In solution, these adducts act as intermediates in the formation of insertion products or in cycloaddition reactions. The extreme manifestation is observed when Me2Ge is combined with a reactive diene in the presence of 18-crown-6. Only the polymerized product, (Me2Ge) , is ultimately isolated. Complexes of germylenes with heteroatom-containing substrates have been characterized at low temperatures . 

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