Synthesis, Structure and Chemical Transformations of Ethynylgermatranes

Abstract

Ethynylgermatranes have been prepared from monosubstituted acetylenes by a three‐step synthesis without isolation of the hydrolytically unstable intermediate chlorogermanes and ethoxygermanes. Boiling an equimolar mixture of tetrachlorogermane Cl4Ge, acetylene RC≡CH and triethylamine in hexane leads to germylation of the Csp−H bond and the formation of ethynyl‐substituted trichlorogermanes. Subsequent alkoxylation of chlorogermanes by ethanol in the presence of triethylamine affords triethoxygermanes that then take part in transalkoxylation with triethanolamine to give ethynylgermatranes. The molecular structures of all ethynylgermatranes and the hexacarbonyldicobalt complex of 1‐heptynylgermatrane have been determined by X‐ray crystallography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Coordinating Ability of Anions, Solvents, Amino Acids, and Gases towards Alkaline and Alkaline‐Earth Elements, Transition Metals, and Lanthanides

“…While the neutral N(EtOH) 3 species presents a low affinity for transition metals ( a TM =0.1), the mono and dianionic derivatives are 100 % coordinated. The trianion, instead, has an index of 1.2 (94 % coordination), and the slight decrease in coordination ability is due to the existence of five compounds in which N(EtO) 3 3− is coordinated to Sn or Ge, rather than to the transition metal present . Interestingly, a structure with this trianion, retrieved by the semi‐coordination protocol shows an unexpected coordination mode: a Ti III cation is coordinated by nine hydrogen atoms of the ethyl groups and by three oxygen atoms of three monodentate anions, as illustrated in Figure .…”

Synthesis and Application of Heterocyclic Germatranes via Rhodium‐Catalyzed Directed C−H Activation/Annulation with Alkynyl Germatranes and Palladium‐Catalyzed Cross‐Coupling

“…In fact, only ethynyl-Ge was synthesized by this strategy (Scheme 2a). Based on previous reports, [16] we attempted to synthesize alkynyl-Ge directly from commercial available terminal alkynes.…”