Showing papers by "Chizuko Kabuto published in 2009"
TL;DR: Using DFT calculations and PMO theory, the origin of the bent and fluxional skeleton of the heavy allenes is ascribed to the Jahn-Teller distortion associated with the effective pi-sigma* mixing (pi-s Sigma* distortion).
Abstract: The synthesis, X-ray and spectroscopic analysis, and unusual bonding and structure among heavy group-14 element congeners of allene (heavy allenes) [R2M═M′═MR2; M = M′ = Si (1a), M = Si, M′ = Ge (1...
61 citations
TL;DR: In this paper, the photoreactivities of a series of diynediammonium dienecarboxylates in the crystalline state were investigated and it was shown that the alignment of diene moieties is very similar to those of topochemically polymerizable diene derivatives.
Abstract: We have investigated that photoreactivities of a series of diynediammonium dienecarboxylates in the crystalline state. In the case of 4,4′-butadiynedibenzylammonium disorbate, almost all diene moieties were polymerized during photoirradiation for 8 h. On the other hand, the conversion of diyne moieties was still low. Crystal structure of the monomer crystal indicates that the alignment of diene moieties is very similar to those of topochemically polymerizable crystals of diene derivatives. Even though the translation distance of diyne moieties is also suitable for the polymerization, the tilt angle is different from the ideal angle. It is the reason why the conversion of diyne moieties was low. By X-ray single-crystal structure analysis of the polymer crystal, we confirmed that the polymerization proceeded via topochemical reaction mechanism indeed. On the other hand, photodimerization of diene moieties in the crystals of 2,4-hexadiyne-1,6-diammonium (E,E)-muconate occurred because of the face-to-face ali...
35 citations
TL;DR: The proposed structure of the maduropeptin chromophore, the biologically active component of the highly potent chromoprotein antitumor antibiotics, was stereoselectively synthesized but did not satisfy the spectra of the natural product.
Abstract: The proposed structure of the maduropeptin chromophore, the biologically active component of the highly potent chromoprotein antitumor antibiotics, was stereoselectively synthesized but did not satisfy the spectra of the natural product. We demonstrated that the correct structure is diastereomeric, which possesses an antipodal sugar moiety.
20 citations
TL;DR: Novel eta(3)-silapropargyl/alkynylsilyl complexes Cp*(CO)(2)Mo(eta( 3)-Ph(2)SiCCR) (3a, R = (t)Bu; 3b,R = (i)Pr) were synthesized by the reactions of Cp-CO(2)(MeCN)MoMe with alkynylsilanes HPh( 2)SiC[triple bond
Abstract: Novel η3-silapropargyl/alkynylsilyl complexes Cp*(CO)2Mo(η3-Ph2SiCCR) (3a, R = tBu; 3b, R = iPr) were synthesized by the reactions of Cp*(CO)2(MeCN)MoMe (1) with alkynylsilanes HPh2SiC≡CR. The structures of 3a and 3b were fully characterized by NMR spectroscopy and X-ray crystallography. The reaction of 3a with MeOH at room temperature gave the stable four-membered metallacycle Cp*(CO)2MoC(═CHtBu)SiPh2OMe (5a), while the corresponding reaction of 3b led to the formation of the η3-allyl complex Cp*(CO)2Mo{η3-(MeOPh2Si)HCCHCMe2} (7) via Cp*(CO)2MoC(═CHiPr)SiPh2OMe (5b).
15 citations