Stable germylenes

Stable germylene (97) with 2,5-dimethyl-2,3,4-hexatriene and A -phenylmaleimide provided the stable germirane derivatives, bis(alkylidene)germirane (98) and bicy-clogermirane (99, Scheme 14.47). ... 

The reactions of a stable germylene ( GeDis2) with ethylene afforded the first... 

UV spectra of stable germylenes, stannylenes and plumbylenes were recorded in solutions or in the solid phase under inert atmosphere in order to prevent access of oxygen and moisture. Thermochromic transitions have been revealed for many stable solid germylenes, stannylenes and plumbylenes. Their nature has not been studied. 

Similarly to the case of the triatomic species (Section III), comparison of absorption maxima of stable germylenes, stannylenes and plumbylenes bearing the same substituents at different divalent atoms of the Group 14 elements (Table 4) does not reveal any... 

The number of polyatomic germylenes, stannylenes and plumbylenes characterized by their vibrational spectra is still very limited. Only IR spectroscopy was used for this purpose. Unstable molecules were studied in low-temperature inert matrices. The stable germylenes, stannylenes and plumbylenes were treated by standard means. 

Besides the triatomic CAs, the molecular structures have been determined experimentally for only labile silylidene and germylidene, as shown in Table 10. At the same time most of the stable CAs have been characterized by X-ray analysis or by electron diffraction. The available structural data for some stable germylenes, stannylenes and plumbylenes have partly been presented in Section IV. The comprehensive consideration of the geometries of stable CAs is beyond the scope of the present review. 

A stable germylene containing tetraaza macrocyle, i.e. dibenzotetraaza[14]annulene (tmtaa), and a variety of cyclic germylenes (such as 30) readily act as two electron donors to form a variety of metal complexes101,140-144. 

The reaction of the stable germylene 32 with a triarylmethylium ion gave not the expected germylium ion 33, but in a series of unexpected rearrangements, the germy-lium ion 34, which is intramolecularly stabilized by interaction of the electron-deficient germylium center with a remote aryl group (Scheme 16).80... 

Reactions of Germylenes with Stabilized Radicals. The stable germylene Ge[C4H4(SiMe3)4] reacts with 2 equivalents 2,2,6,6-tetramethylpiperidine N-oxide (TEMPO, -ONR2) to... 

A germirane intermediate without substituents in the ring carbon atoms 36 was detected by H NMR in the reaction of a stable germylene with ethylene to produce 1,2-digermacyclobutane. When the reaction mixture was allowed to stand for a few days, the intermediate germirane 36 gradually was converted into the product 37 (see Scheme 5). Attempts to isolate 36 were unsuccessful <19950M2139>. 

The complex tmtaaGeCr(CO)s, is isolated from the stable germylene and the transition metal fragment in good yield . The Ge=Cr bond length is 2.500(2) A. 

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