123347-02-4Relevant academic research and scientific papers
Platinum-catalyzed bis-germylation of alkynes with organodigermanes and cyclic oligogermanes
Mochida, Kunio,Wada, Tohru,Suzuki, Kaoru,Hatanaka, Wakako,Nishiyama, Yuriko,Nanjo, Masato,Sekine, Akiko,Ohashi, Yuji,Sakamoto, Masato,Yamamoto, Akio
, p. 123 - 137 (2007/10/03)
Hexamethyldigermane, Me3GeGeMe3, reacted with various alkynes in the presence of platinum complexes at 120 °C to afford Z-1,2-bis(germyl)ethenes in moderate to good yields. Terminal alkynes exhibit higher reactivities than internal ones. [Pt(acac)2] and [Pt(dba)2] serve as efficient catalysts, while [Pt(PPh3)4], [PtCl2(PPh3)2], and [Pt(dba)2]-phosphite were found to be inactive. Four- and six-membered cyclic oligogermanes, such as dodecamethylcyclohexagermane, (Me2Ge)6, reacted with alkynes in the presence of platinum catalysts to yield 1,4-digermacyclohexa-2,5-dienes in ca. 30% yield. The reactions of phenylacetylene with 1,2-digermacyclohexa-3,5-dienes afforded the corresponding 1,4-digermacycloocta-2,5,7-trienes in 93% yield. Bis(germyl)platinum complexes having various tertiary phosphine ligands have been prepared as models of a key intermediate in the above mentioned catalytic bis-germylation of alkynes, and their structures have been established by spectroscopic methods and X-ray crystallography. Bis(germyl)platinum complexes reacted with phenylacetylene to give the corresponding insertion products, germyl(germylvinyl)platinum species, whose structures have been determined by spectroscopic and X-ray analysis. Germyl(germylvinyl)platinum complexes were found to liberate a bis-germylation product of the alkyne upon heating. The result supports a mechanism involving the oxidative addition of a digermane to a Pt(0) complex, the insertion of an alkyne into one of the two Pt-Ge bonds to give a germyl(germylvinyl)platinum species, and the reductive elimination of the bis-germylation product of the alkyne. Evidence suggesting the extrusion of a germylene unit from the bis-germylplatinum species has been obtained, accounting for the generation courses of other by-products.
Chemistry of heavy carbene analogues R2M (M = Si, Ge, Sn). 16. Reactions of free dimethylgermylene with alkynes and their palladium catalysis
Billeb, Gilbert,Brauer, Hartmut,Neumann, Wilhelm P.,Weisbeck, Markus
, p. 2069 - 2074 (2008/10/08)
Free dimethylgermylene, Me2Ge (1), reacts with alkynes RC≡CR′ (3) to give a multitude of four-, five-, and six-membered germaheterocycles 4-6,8, containing one, two, or even three Ge atoms, or the acyclic 3-germapent-1-en-4-yne 7. The nature of R and R′ (H, alkyl, or aryl) determines whether 1,4-digermacyclohexa-2,5-dienes 4, 1-germacyclopenta-2,4-dienes 6, or 1,2,3-trigermacyclopent-4-ene8 5 are formed. Hexafluoro-2-butyne gives the corresponding 1,2-digermacyclobut-3-ene 8. The mechanisms of product formation are discussed. Germirenes 11 or, in special cases, the digermene Me2Ge=GeMe2 (10) and the cyclotrigermane (Me2Ge)3 (12) are proposed as intermediates. A number of alkynes 3 which do not form isolable products with 1 give compounds 4 or 6 when catalytic amounts of (Ph3P)4Pd are present.
