Masayoshi Onishi

Heteropolynuclear Complexes of 3,5-Dimethylpyrazolate [Pt2M4(Me2pz)8] (M = Ag, Cu). Highly Luminescent Character of the Triplet Excited State Based on Mixed-Metal Cores

The platinum dimer and heteropolynuclear platinum complexes of 3,5-dimethylpyrazolate, [Pt2M4(mu-Me2pz)8] [M = H (1), Ag (2), Cu (3)], were synthesized and structurally characterized. They exhibit yellow, sky-blue, and orange luminescence, respectively, in the solid state. The absorption bands of 2 and 3 are mainly assigned to the combination of the metal-metal-to-ligand charge-transfer and [Pt2 --> Pt2M4] transitions by the time-dependent density functional theory (DFT) method. DFT calculations also indicate that the emissive states of 2 and 3 are 3[Pt2 --> Pt2Ag4] and 3[Cu(d) --> Pt2Cu4], respectively.

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.

Luminescent Heteropolynuclear Complexes of 3,5‐Dimethylpyrazolate [Pt2Au2M2(Me2pz)8] (M=Ag, Cu) Showing the Synergistic Effect of Three Transition Elements in the Excited State

Swap the coins! The Pt(2)Au(2), Pt(2)Au(2)Cu(2), and Pt(2)Au(2)Ag(2) complexes of 3,5-dimethylpyrazolate exhibit yellow-green, orange, and sky-blue luminescence, respectively (see figure). The emission energies of Pt(2)Au(2)M(2) complexes can be controlled by the change of the third coinage metal ions M. The Pt(2)Au(2)M(2) complexes take the cis configuration with respect to the Au(2)M(2) plane.

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.

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 and Luminescent Properties of 3,5-Diphenylpyrazolato-Bridged Heteropolynuclear Platinum Complexes. The Influence of Chloride Ligands on the Emission Energy Revealed by the Systematic Replacement of Chloride Ligands by 3,5-Dimethylpyrazolate

Heteropolynuclear Pt(II) complexes with 3,5-diphenylpyrazolate [Pt(2)Ag(4)(μ-Cl)(2)(μ-Ph(2)pz)(6)] (3), [Pt(2)Ag(2)Cl(2)(μ-Ph(2)pz)(4)(Ph(2)pzH)(2)] (4), [Pt(2)Cu(2)Cl(2)(μ-Ph(2)pz)(4)(Ph(2)pzH)(2)] (5), [Pt(2)Ag(4)(μ-Cl)(μ-Me(2)pz)(μ-Ph(2)pz)(6)] (7), and [Pt(2)Ag(4)(μ-Me(2)pz)(2)(μ-Ph(2)pz)(6)] (8) have been prepared and structurally characterized. These complexes are luminescent except for 5 in the solid state at an ambient temperature with emissions of red-orange (3), orange (4), yellow-orange (7), and green (8) light, respectively. Systematic red shift of the emission energies with the number of chloride ligands was observed for 3, 7, and 8. DFT calculations indicate that the highest occupied molecular orbital (HOMO) as well as HOMO-1 of the heterohexanuclear complexes, 3, 7, and 8, having Pt(2)Ag(4) core, mainly consist of dδ orbital of Pt(II) and π orbitals of Ph(2)pz ligands, while the lowest unoccupied molecular orbital (LUMO) of these complexes mainly consists of in-phase combination of 6p of two Pt(II) centers and 5p of four Ag(I) centers. It is likely that the emissions of 3, 7, and 8 are attributed to emissive states derived from the Pt(2)(d)/π → Pt(2)Ag(4) transitions, the emission energy of which depends on the ratio of chloride ligands to pyrazolate ligands.

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.

Reactions of a 2-picolyl-bridged palladium(ii) complex with some pyrazole derivatives

Abstract A 2-picolyl-bridged dinuclear complex, [Pd(2-picolyl)Cl(PPh3)2] (I) reacted with alkali metal salts of poly(1-pyrazolyl)borates, Na(BPz4) (Pz = 1-pyrazolyl), Na(HBPz3),and K(H2BPz2) to afford the complexes, [Pd(2-picolyl)(BPz4)2] (II), [Pd(2-picolyl)(HBPz3)(PPh3)] (III), and [Pd(2-picolyl)(H2BPz2)2] (V), respectively. Complexes II and V retained the 2-picolyl bridge, whereas III was mononuclear without the bridge. Complex I was treated with hydrated silver perchlorate in the presence of tris(1-pyrazolyl)methane to give [Pd(2-picolyl)(OH2)(PPh3)2](ClO4)2 (VI) without incorporating the neutral ligand.