Kiyotaka Onitsuka

The third-generation dendrimer with 45 platinum atoms (shown schematically) was synthesized efficiently by a convergent methodology in which two different trialkylsilyl groups (symbolized by the nodal points) are used to protect the bridging triethynylbenzene derivatives. PT=[Pt(PEt₃ )₂ ].

Entwurf eines chiralen Katalysators: Der gezeigte planar-chirale Cyclopentadienyl-Rutheniumkomplex ist ein wirkungsvoller Katalysator für Reaktionen unsymmetrisch substituierter Allylhalogenide mit Phenol und Alkohol. Die Umsetzungen ergeben verzweigte Allylether mit hohen Regio- und Enantioselektivitäten. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2001/2008/z704457_s.pdf or from the author. Please note: The publisher is not responsi

Single-handed helical polymers of the type 2 are the products of the screw-sense-selective polymerization of achiral isocyanides ArNC initiated by the helical oligomer complexes 1. The latter are accessible from μ-ethynediyl-bridged dinuclear Pd,Pt complexes by reaction with 3-CNC6H4CO2R* (R* = (+)- and (-)-menthyl).

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReactions of Heterodinuclear .mu.-Ethynediyl Palladium-Platinum Complexes with Isocyanides: Living Polymerization of Aryl IsocyanidesKiyotaka Onitsuka, Koichi Yanai, Fumie Takei, Takashi Joh, and Shigetoshi TakahashiCite this: Organometallics 1994, 13, 10, 3862–3867Publication Date (Print):October 1, 1994Publication History Published online1 May 2002Published inissue 1 October 1994https://pubs.acs.org/doi/10.1021/om00022a022https://doi.org/10.1021/om00

The living polymerization of aryl isocyanides has been achieved with the PdPt–ethynediyl complexes 1. The molecular weight distribution is very narrow for the polymers 2 (n̄ = 10) and 3 (n̄ = 100), and the same end groups as in complex 1 ensure the living nature of the polymerization. If the ratio of isocyanide to 1 is restricted to 2:1, a double-insertion product can be isolated. R = Et, nBu; Ar = Ph, 4-NO2C6H4 inter alia.

Less is more: A new route to access chiral allylic alcohols through the regio- and enantioselective substitution of monosubstituted allylic chlorides with water has been developed. The reaction is catalyzed effectively by planar-chiral cyclopentadienyl ruthenium complexes (see scheme). Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors.

Novel trinuclear ruthenium complexes have been prepared by using tri(4-ethynylphenyl)amine as a bridging ligand. Cyclic voltammetry of the trinuclear ruthenium complexes revealed stepwise quasi-reversible redox behavior of three ruthenium-acetylide species and the central triphenylamine unit, whereas the mononuclear analog showed two sequential quasi-reversible redox waves. The spectroelectrochemical UV-VIS spectral studies suggested that the 1e- oxidized triruthenium species was stable and show

Bulky aryl isocyanide monomers possessing tert-butyl groups at the ortho position and chiral ester or amide groups at the para position were prepared and polymerized by arylrhodium complex to give polyisocyanides with narrow polydispersity indexes in good yields. The large specific rotation and the intense Cotton effect at 347 nm suggest that the resulting polymers maintained predominantly one-handed helical conformation in solution. The chiroptical properties were increased with an increase in

Minimization of steric interactions between the phosphane ligands as well as the geometry of the bridging ligands are responsible for the selective formation of tetranuclear macrocycle 1 in the reaction of [PdCl2(PEt3)2] with an equimolar quantity of o-diethynylbenzene, though the angle of 60° between the two acetylene groups would be expected to result in a trinuclear complex.

An efficient convergent route to the main chain type of organometallic dendrimers, in which platinum moieties are linked by 1,3,5-triethynylbenzene, has been developed. The synthesis of platinum-acetylide dendrons involved the use of two types of trialkylsilyl groups for protection of the terminal acetylene. The platinum-acetylide dendrimers were prepared up to the third generation by reacting dendrons with a triplatinum core and a tetraplatinum core. Spectroscopic characterization and trace exp

Well-defined arylrhodium complexes Rh(Ar)(nbd)(PPh3) (Ar = Me2C6H3, 2,4,6-Pri3C6H2, 2-PhC6H4, 2-Me-1-naphthyl, 9-anthracenyl, C(Ph)CPh2; nbd = 2,5-norbornadiene) that were prepared from the reaction of [Rh(nbd)Cl]2 with LiAr and PPh3 effectively initiated the living polymerization of aryl isocyanides possessing bulky substituents at the ortho position in the presence of PPh3 to give poly(isocyanide)s with narrow polydispersity indexes in good yields. The bulky aryl groups on the Rh complex were

Intramolecular energy transfer from platinum–acetylide moieties to the porphyrin core was observed in novel organometallic dendrimers that were prepared from a tetra(4-ethynylphenyl)porphyrin-bridged tetranuclear platinum–acetylide core and platinum–acetylide dendrons by a convergent method.

The µ-ethynediyl-dipalladium complexes [X(R3P)2PdCCPd(PR3)2X]1(X = Cl or I, R = Et or Bu) react with aryl isocyanides R′NC(R′= Ph, 4-NO2C6H4, or 2,6-Me2C6H3) to give double-insertion products [X(R3P)2PdCCC(NR′)C(NR′)Pd(PR3)2X]2, selectively. Complexes 2 have been characterized by IR, mass, 1H, 13C-{1H}, and 31P-{1H} NMR spectra. Selective double insertion is peculiar to the µ-ethynediyl dinuclear complexes, and other dipalladium complexes [Cl(R3P)2PdCCYCCPd(PR3)2Cl](Y = bond or C6H4) and mononuc

Planar-chiral cyclopentadienyl-ruthenium complexes serve as effective catalysts for the kinetic resolution of racemic allylic carbonates in asymmetric allylic alkylation. The absolute configurations of the recovered carbonates and the alkylation products are dependent on the substituent on the cyclopentadienyl group at the 4-position of the ruthenium catalyst.