Reactions with germylenes

The chemically significant heteroleptic germylene 11 (Tbt)(Tip)Ge was prepared in two steps (Equation (243)) and undergoes reactions with typical trapping reagents (Scheme 46).246... 

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

Although very little is known for the reactions of isolated germylenes 146, 147, and 148, diarylgermylene (150) was found to undergo a variety of reactions with olefins, dienes, acetylenes, alcohols, isothiocyanates, elemental chalcogens, and hydrosilanes as in the cases of less hindered, transient germylenes previously reported. 

In addition to carbenes and nitrenes, organometallic species such as germylenes 107 have been utilized in [2 + 1] cycloadditions and, upon reaction with thioketones, afforded the corresponding thiagermiranes which are very stable and do not decompose even when heated to their melting point438 (equation 124). 

Methylphenylgermylene was generated by retrocycloaddition from the germana-cyclopentane analogue.107 The germylene was detected directly and by analysis of reaction products. Rate constants for the reactions with amines, acids, silanes, stan-nanes, oxygen, and unsaturated carbon-carbon bonds were given. 

The reaction of germylene 134 with /< rt-butylphosphaalkyne gave germadiphosphacyclobutene 33, possessing both two- and three-coordinated phosphorus atoms. It was assumed that the reaction started with the addition of 134 to the phosphaalkyne to afford a three-membered ring system. Cyclodimerization of this intermediate yielded the final product 33 (Scheme 49) <2001CC215>. 

Thus, the sign of the observed polarization of the Me protons of the product 22 (absorption) is unambiguous evidence of the formation of an intermediate triplet 1,3-biradical 23T, and this fact, in turn, means that 16 enters the reaction with 21 in the excited triplet state. The end product 22 is formed after the triplet-singlet conversion of the triplet biradical 23t followed by cyclization of the singlet biradical 23s (Scheme 11), while the triplet biradical 23T also reverts to the initial reagents. Only this reverse reaction could explain the negative polarization (emission) of the Me protons of the initial thiacycloheptyne 21. It should be noted that the process described in Scheme 11 is the first example of a reaction of the excited triple state of germylene 1676. 

Germanates are ammonium salts in which the counterion is a germylanion (equation 49)65. They are generally prepared from acidic hydrogermanes by reaction with a Lewis base N. Sometimes they decompose reversibly to germylene in the presence of... 

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