Shigetoshi Takahashi

Syntheses and properties of cis- and trans-dialkynyl complexes of platinum(II)

Abstract Selective syntheses of cis - and trans -platinum(II) acetylide complexes of the type (R 3 P) 2 Pt(CCR′) 2 (where R = Et or n-Bu, R′ = H, CHCH 2 , CCH, Ph or p -C 6 H 4 CCH), and systematic studies on characterization of the cis - and trans -isomers by spectroscopic methods are reported.

Linear polymers containing transition metals in the main chain

In recent years linear polymers containing transition metals have attracted much interest. There are two types of organometallic polymers in which the metal-containing portion is either a part of the polymer main chain or bound to the polymer as a pendant group. In this article the recent studies on the former type of linear polymers are reviewed on the basis of the following three parts: 1 metallocene-containing polymers; 2 linear “Werner-type” coordination polymers; 3 polymers containing sigma-bonded transition metals in the main chain. The main part of this review is devoted to a new class of soluble metal-poly-yne polymers in which transition metal atoms are joined in the main chain by a metal-carbon σ-bond.

Novel preparation of σ-alkynyl complexes of transition metals by copper(I) iodide-catalysed dehydrohalogenation

Transition metal alkynyl complexes have been prepared conveniently in high yields under mild conditions by the direct reaction of acetylenes with metal halides in the presence of catalytic amounts of copper(I) iodide in diethylamine.

Convergent Route to Organometallic Dendrimers Composed of Platinum–Acetylide Units

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 ].

Studies of poly-yne polymers containing transition metals in the main chain : III. Synthesis and characterization of a poly-yne polymer containing mixed metals in the main chain,

Abstract By the reaction of trans -(PBu 3 ) 2 Pt(CCCCH) 2 with trans -(PBu 3 ) 2 PdCl 2 , the title polymer, (II), has been prepared and characterized by spectral and analytical data. The alternating regularity of the metal arrangement in II was confirmed by the selective formation of the trinuclear complex trans,trans,trans -ClPd(PBu 3 ) 2 −CCC CPt(PBu 3 ) 2 −CC-CCPd(PBu 3 ) 2 (XXIII), in the depolymerization by trans- (PBu 3 ) 2 PdCl 2 using CuI as catalyst in XXNEt 2 .

Preparation and properties of cyclodextrin–ferrocene inclusion complexes

One-to-one inclusion complexes were obtained in crystalline state in high yield by the treatment of β-and γ-cyclodextrin (CD)with ferrocene (FcH) and its derivatives (FcR), while α-cyclodextrin formed 2:1 [CD:FcR (FcH)] complexes with ferrocene and the monosubstituted derivatives.

A novel route to 2,3-disubstituted indoles via palladium-catalyzed three-component coupling of aryl iodide, o-alkenylphenyl isocyanide and amine

Three-component coupling reactions of aryl iodide, o-alkenylphenyl isocyanide and amine in the presence of palladium catalysts produced 2,3-substituted indoles in moderate yields.

Studies of poly-yne polymers containing transition metals in the main chain : VI. Synthesis of nickel-poly-yne polymers by alkynyl ligand exchange using a copper(I) catalyst.

Reactions of trans-bis(Tri-n-butlphosphine)diethynylnickel(Ia) with 1-alkynes in the presence of an amine complex of a copper(I) salt as a catalyst give quantitatively alkynyl ligand exchange products. By this method, complex(Ia) reacts with appropriate α,ω-diethynyl compounds to afford high molecular weight linear polymers in good yields. This procedure provides a convenient route to such nickel-poly-yne polymers.

Screw-Sense-Selective Polymerization of Aryl Isocyanides Initiated by a Pd-Ptμ-Ethynediyl Dinuclear Complex: A Novel Method for the Synthesis of Single-Handed Helical Poly(isocyanide)s with the Block Copolymerization Technique

Living polymerization of chiral aryl isocyanides, such as m- and p-menthoxycarbonylphenyl isocyanides 2 and 5, initiated by the Pd-Pt mu-ethynediyl dinuclear complex 1, proceeds with a high screw-sense selectivity to give the poly(isocyanide)s 3 and 6, which exhibit a large specific rotation and an intense CD band at lambda = 364 nm as a consequence of a helical chirality. The molar optical rotation and molar circular dichroism of the resulting polymers 3 and 6 reach a constant value at a degree of polymerization (Pn) of more than 30. Screw-sense-selective polymerization of achiral aryl isocyanides that bear very bulky substituents, such as 3,5-di(propoxycarbonyl)phenyl isocyanide (11), 3,5-di(butoxycarbonyl)phenyl isocyanide (13), and 3,5-di(cyclohexyloxycarbonyl)phenyl isocyanide (15), is achieved by the use of chiral oligomer complexes 3(30) and 6(30), prepared from the reaction of 1 with 30 equivalents of 2 or 5, as an initiator to give predominantly single-handed helical polymers. In contrast, smaller aryl isocyanides are also polymerized by 3(30) and 6(30) with screw-sense selectivity in the initial stage of the reaction, but the single-handed helix is not preserved up to high molecular weight. Kinetic studies of the polymerization of (L)- and (D)-2, or (L)- and (D)-5 with chiral oligomer complexes (L)-3(50) or (L)-6(100) suggests that the screw sense of the polymer backbone is not controlled kinetically, but rather that the thermodynamically stable screw sense is produced.

Synthesis of organometallic dendrimers with a backbone composed of platinum-acetylide units

Abstract Novel organometallic dendrimers containing platinum-acetylide units in the main chain have been synthesized up to a henicosanuclear complex (12) using triethynylmesitylene (4) as a bridging ligand. The molecular structure of trinuclear complex (5b), which is a model core of the dendrimer, has been established by an X-ray analysis.