Yoshito Takeuchi

Synthesis and structure of tris[(2-alkoxymethyl)phenyl]germanes and tris[(2-methylthiomethyl)phenyl]germane

Abstract Tris[(2-alkoxymethyl)phenyl]germanes and tris[(2-methylthiomethyl)phenyl]germane were prepared and their structures were investigated by means of X-ray crystallographic analysis and 73Ge NMR spectra, which indicated incipient dative bonding between germanium and sulfur or oxygen atoms to make the germanium atom hexavalent and heptavalent, respectively.

73Ge NMR Spectroscopy of Organogermanium Compounds

Abstract Recent advances in 73 Ge NMR spectroscopy are reviewed. Following the introduction (Section 1), Section 2 describes recently determined chemical shifts and linewidths for a variety of organogermanium compounds which range from normal (tetravalent) to hypercoordinated (up to heptavalent) species. The role of linewidth as evidence for hypercoordination is discussed. In Section 3, coupling constants, relaxation times and relaxation mechanisms are discussed in detail, showing that in some cases a mechanism other than quadrupolar is involved. In the last section, high-resolution solid-state 73 Ge NMR spectroscopy is covered which has not been treated in previous reviews.

Synthesis of azacrown ethers modified with side-chains containing germanium

Abstract The reaction between ethanolamine ( 4 ) and tri- or tetraethylene tosylate ( 5 ) and ( 13 ) gave 9- and 12-membered monoazacrowns with a ue5f8CH 2 CH 2 OH residue on nitrogen, A-OH and B-OH , together with 18- and 24-membered diazacrown ethers with the same substituent on nitrogen, E-OH and F-OH. If 2-(2-aminoethoxy)ethanol ( 12 ) was used in the reaction described above, instead of 4 , the final products, G-OH and H-OH , and K-OH and L-OH , have a longer side chain, ue5f8CH 2 CH 2 OCH 2 CH 2 OH, on nitrogen (Route 1). A series of reactions involving bromoethanol ( 6 ) and diethanolamine ( 9 ) formed, with 5 or 13 , 18- and 24-membered monoazacrowns with the shorter substituent as described above, a 15-membered monoazacrown ether C-OH and an 18-membered D-OH . If 2-(2-chloroethoxy)ethanol ( 14 ) is used instead of 6 , I-OH and J-OH are obtained (Route 2′). All these hydroxy azacrown ethers were made to react with 3-trimethylgermylpropionic acid ( 18 ) to give the corresponding germanium-containing A – L . A preliminary investigation was carried out on the cation transport capability of these germanium-containing azacrown ethers to observe whether germanium might enhance their cation transporting capability.

Synthesis of 5,5,6,6,21,21,22,22-octamethyl-5,6,21,22-tetragerma[10.10]paracyclophane

Abstract A [10,10]paracyclophane, 5,5,6,6,21,21,22,22-octamethyl-5,6,21,22-tetragerma[10.10]paracyclophane ( 4a ), with two ue5f8R 1 R 2 GeGeR 1 R 2 ue5f8 moieties in the center of two bridges, was prepared. An attempt to synthesize cyclophanes, 4b (R 1 =Me; R 2 =Ph) and 4c (R 1 =R 2 =Ph) was also made. The products were not analytically pure even after strenuous purification procedure to indicate that a double Wurtz coupling reaction is extremely difficult and necessarily accompanied by formation of polymeric by-products.

First observation of high-resolution solid-state 73Ge NMR spectra of organogermanium compounds

High-resolution solid-state MAS 73Ge NMR spectra of norganogermanium compounds have been observed for the first time; the nchemical shifts and half-widths of tetraphenylgermane and ntetrabenzylgermane were recorded with and without high-power ndecoupling.

Strategy for globalization of chemical education based on the Internet

It is likely that in the age of globalization, chemical education cannot be unaffected by this trend. The essential prerequisite for globalization would be a common curriculum. It has long been assumed that a common curriculum is technically impossible because of the difficulty involved in the dissemination of information. There is now a realistic possibility that this difficulty will be substantially reduced, if not eliminated, by use of the Internet. Difficulties involved in the translation of text will also be reduced by the use of accurate and low-cost translation software. Under such circumstances, what is urgently needed is the establishment of teaching materials translation centers around the world.

VIRTUAL CHEMICAL EDUCATION-NOVEL TEACHING MATERIALS BY MEANS OF THE INTERNET

Department of Chemistry, Faculty of Science, Kanagawa University, 2946 Tuchiya, Hiratsuka, Japan 259-1293 Department of Information Sciences, Faculty of Science, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan Department of Chemistry, Faculty of Science, Hiroshima University, Higashi-Hiroshima, Japan 739-8526 Faculty of Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo, Japan 192-8577

Synthesis and structure of a novel pentacoordinate organogermanium compound

Reaction between ButGeCl3 and mercaptoacetic acid afforded a novel type of pentacoordinate germanium compound via ButGe(SCH2CO2H)3 which loses one mole of SCH2CO2H to afford the pentacoordinate species.