Katsuma Hiraki

Preparation of cationic (keto-stabilized phosphonium or sulphonium ylide)(η5-cyclopentadienyl)(triphenylphosphine)palladium(II) complexes

Abstract In the presence of AgClO4, chloro(η5-cyclopentadienyl)(triphenylphosphine)palladium(II) was treated with triphenylphosphonium benzoylmethylid

Syntheses and characterization of some new 2-picolylpalladium(II) complexes

Abstract The 2-picolylpalladium(II) complex [{Pd(CH2Py)Cl(PPh3)}2] (CH2Py=2-picolyl) (I), prepared from 2-picolyl chloride and [Pd(PPh3)4], was treated with lithium bromide, silver acetate, 4-picoline (pic) and silver perchlorate, thallium acetylacetonate{Tl(acac)}, sodium dimenthyldithiocarbamate-water-(1/2) {Na(dmdc). 2 H2O}, and 1,2-bis(diphenylphospino)ethane (dppe) to yield [{PdBr(CH2Py)(PPh3)}2] (II), [{Pd(CH2Py)OAc(PPh3)}2] (III), [{Pd(Ch2Py)(pic)(PPh3)}2](ClO4)2 (IV), [Pd(CH2Py)(acac)(PPh3)] (V), [Pd(CH2Py)(dmdc)(PPh3)] (VI), and [Pd(Ch2Py)Cl(dppe)] (VII), respectively. Halogen abstraction from VII using silver perchlorate afforded an ionic complex [{Pd(CH2Py)(dppe)}2](ClO4)2 (VIII). It was concluded that the 2-picolyl groups in these eight complexes are σ-bonded to palladium, and that in the dinuclear complexes I, II, III, IV, and VIII, they serve as bridging ligands.

Organoruthenium(II) complexes formed by insertion reactions of some vinyl compounds and conjugated dienes into a hydrido–ruthenium bond

The hydridoruthenium(II) complex [ RuCl(CO) H (PPh3)3](1) reacted easily with methyl acrylate and N,N-dimethylacrylamide to give the corresponding insertion products,[[graphic omitted]OMe}Cl(CO)(PPh3)2](2a) and [[graphic omitted]NMe2}Cl(CO)(PPh3)2](3), respectively. Similarly, complex (1) reacted with 2-vinylpyridine and 5-ethyl-2-vinylpyridine to afford the C1,N-chelating organoruthenium(II) complexes, [[graphic omitted]}Cl(CO)(PPh3)2](4a) and [[graphic omitted]}Cl(CO)(PPh3)2](5) respectively. Complexes (2a) and (4a) reacted with LiBr·H2O to give the analogous bromo-complexes. The conjugated dienes, penta-1,3-diene, isoprene, and methyl sorbate were treated with (1) to yield the η3-allylic ruthenium(II) complexes, [Ru{η3-R1C(H)C(R2)CHR3}Cl(CO)(PPh3)2][(6) R1= R3= Me, R2= H; (7) R1= R2= Me, R3= H; (8) R1= Et, R2= H, R3= CO2Me], respectively. On the basis of 1H and 13C-{lH} n.m.r. data, it has been concluded that the two PPh3 ligands in (2)–(5) are located trans to each other, whereas those in (6)–(8) are cis.

Metallation of aliphatic carbon atoms. II: Syntheses and characterization of the cyclopalladated complexes of N,N-dimethylneopentylamine

Abstract N,N -Dimethylneopentylamine reacts with Pd(MeCO 2 ) 2 to give a novel trinuclear cyclopalladated complex [Me 2 NCH 2 CMe 2 CH 2 Pd(μ-MeCO 2 ) 2 Pd(μ-MeCO 2 ) 2 PdCH 2 CMe 2 CH 2 NMe 2 ]•-0.5C 6 H 6 (I). The reaction of I with PPh 3 affords both trans -[Pd(MeCO 2 ) 2 (PPh 3 ) 2 ] (II) and [Pd(CH 2 CMe 2 CH 2 NMe 2 )(MeCO 2 )(PPh 3 )] (III). The reaction of III with LiCl yields a mononuclear cyclopalladated complex, [Pd(CH 2 CMe 2 CH 2 NMe 2 )Cl(PPh 3 )] (IV).

Cyclopalladation of benzyldiphenylphosphine by palladium(II) acetate

Abstract An acetato-bridged binuclear cyclopalladated complex of benzyldiphenylphosphine, [{Pd(C 6 H 4 CH 2 PPh 2 )(O 2 CMe)}], has been obtained by the reaction between the phosphine and palladium(II) acetate. A chloro-bridged analogue, [{Pd(C 6 H 4 CH 2 PPh 2 )Cl} 2 ], yielded by the metathetical reaction of the acetato-bridged complex with LiCl, undergoes bridge-splitting reactions with 3,5-dimethylpyridine (dmpy) and thallium(I) acetylacetonate (Tl[acac]) to give mono-nuclear cyclopalladated complexes, [Pd(C 6 H 4 CH 2 PPh 2 )Cl(dmpy)] and [Pd(C 6 H 4 CH 2 )(acac)], respectively. These complexes are characterized by means of elemental analysis and IR and NMR spectroscopy.

Synthesis and molecular structure of [RuCl{C(CHPh)OC(O)CH2CH3}(CO)(PPh3)2]: a real intermediate in ruthenium complex-catalyzed selective synthesis of a (Z)-enol ester

Abstract Reaction of [RuCl(η2-O2CCH2CH3)(CO)(PPh3)2] (1) and phenylacetylene gives [RuCl{C(CHPh)OC(O)CH2CH3}(CO)(PPh3)2] (2a). The X-ray structure analysis of 2a reveals that it includes a (Z)-enol ester-like 1-propanoyloxy-2-phenylethenyl-C1,O ligand. In the catalytic addition of propanoic acid to phenylacetylene, the complex 2a acts as a real intermediate that gives (Z)-2-phenylethenyl propanoate, selectively. The presence of the free PPh3 in the reaction mixture depresses formation of some dicarbonylruthenium species that catalytically produce (E)- and Markovnikov-type enol esters.

Syntheses and characterization of cyclopalladated complexes of 2-phenylthiazole

Abstract 2-Phenylthiazole reacts with palladium(II) acetate to give a new cyclopalladated, acetato-bridged binuclear complex, [{Pd(O 2 CMe)(phtz)} 2 ] [phtz = 2-(2′-thiazolyl)phenyl-1- C , N ]. A chloro-bridged analogue, [{PdCl(phtz)} 2 ], produced by the reaction of the acetato-bridged complex with sodium chloride, undergoes bridge-splitting reactions with triphenylphosphine, 3,5-lutidine, and thallium(I) acetylacetonate to give the corresponding mononuclear cyclopalladated complexes. All the new complexes were characterized by means of elemental analysis, and IR and NMR spectroscopy. Reactions of [{PdCl(phtz)} 2 ] with methyl vinyl ketone and styrene afford 2-phenylthiazole and 2-(2′-thiazolyl)stilbene, respectively.

Preparations and characterization of new 2-furfurylpalladium(II) complexes

Abstract 2-Furfuryl chloride reacted with [Pd(PPh 3 ) 4 ] to give [Pd(η 1 -CH 2 Fu)-Cl(PPh 3 ) 2 ] (Fu = 2-furyl) (I) and with bis(dibenzylideneacetone)palladium(0) in the presence of the appropriate amount of PPh 3 or 4-picoline to afford [Pd(η 3 -CH 2 Fu)Cl(PPh 3 )] or [Pd(η 1 -CH 2 Fu)Cl(4-picoline) 2 ], respectively. Complex I was treated with Tl(acac), AgCIO 4 , and Na[BPz 3 R] (Pz = 1-pyrazolyl, R = H or Pz) to give [Pd(η 1 -CH 2 Fu)(acac)(PPh 3 )], [Pd(η 3 -CH 2 Fu)-(PPh 3 ) 2 ]ClO 4 , and [Pd(η 1 -CH 2 Fu)(BPz 3 R)(PPh 3 )], respectively. These new 2-furfurylpalladium(II) complexes were characterized on the basis of elemental analysis, electric conductivity, and spectroscopic data.

Syntheses of new diphenylphosphinoacetatorhodium(I) complexes and their catalytic reactivities in hydrogenation of aromatic compounds

Abstract The diphenylphosphinoacetic acid Ph 2 PCH 2 COOH was readily converted to its silver salt [Ag(Ph 2 PCH 2 COO)] ( 1 ), and subsequent reactions of 1 with [Rh(cod)Cl] 2 (cod=1,5-cyclooctadiene) and [Rh(CO) 2 Cl] 2 gave [Rh(cod)(Ph 2 PCH 2 COO)] ( 2 ) and [Rh(CO) 2 (Ph 2 PCH 2 COO)] ( 3 ), respectively. Spectroscopic data and some physical properties of these new compounds are described. The complexes 2 and 3 at 50 °C showed catalytic hydrogenation activities towards benzene and a variety of substituted benzenes. The turn-over number ( TN ) for the arene hydrogenations with 2 under 5 kg/cm 2 of H 2 , decreased with the following sequence: benzene>; toluene>;anisole>;ethylbenzene>; p - and m -xylenes>;methyl benzoate. Benzonitrile and nitrobenzene did not yield any products with hydrogenated benzene-ring moieties, and the latter substrate gave only aniline. The activity sequence observed for the arene hydrogenation resulted from steric and electron-withdrawing effects of the substituents of the benzene rings. In benzene hydrogenation with 2 under 50 kg/cm 2 of H 2 at 50 °C for 36 h, the TN value was found to be about 5800. Complex 2 also showed similar hydrogenation activities towards 1,2,3,4-tetrahydronaphthalene and furan.

Preparations and fluxional behavior of some tetrakis(1-pyrazolyl)boratopalladium(II) complexes

Dinuclear complexes [Pd2Cl4L2] (L = neutral ligand reacted with Na(BPz4) (Pz = 1-pyrazolyl) to yield [PdCl(BPz4)L] [(I) for L = PEt3 and (II) for L = P(OEt)3] and [(BPz4)Pd(BPz4)PdCl2]·12CH2Cl2 (III) for diethyl sulfide. In the 1H-NMR spectra of I and II, fluxional behavior of the BPz4 ligand was observed at high temperature leading to spectroscopic equivalence of all four pyrazolyl groups, and was studied in connection with trans-effects of other coexisting ligands. A reaction of [PdCl2(en)] (en = ethylenediamine) with Na(BPz4) gave a cationic complex of [Pd(BPz4)(en)]ClO4 (V), of which the 1H-NMR spectra showed inversion of the Pd-(pyrazolyl)2-B six-membered ring, dividing four pyrazolyl groups spectroscopically into two classes of coordinated and uncoordinated groups in a ratio of 2:2.