Preparation, Spectra and Electronic Structures of Tetrahedral Nickel(II) Complexes Containing Triphenylphosphine and Halide Ions as Ligands

Cotton, F. Albert; Faut, O. D.; Goodgame, D. M. L.

doi:10.1021/ja01463a021

Cited by 132 publications

(24 citation statements)

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“…Bis(triphenyl phosphino)nickel(II) chloride NiCl 2 (PPh 3 ) 2 was obtained fol lowing a known procedure. 44 Phenylboronic acid was synthe sized by a known procedure. 45 Dioxane was purified from per oxides and dried following a conventional procedure.…”

Section: Methodsmentioning

confidence: 99%

Structure of (Z)-(5R)-methyl-2-(4-phenylbenzylidene)cyclohexanone as chiral component of liquid-crystalline systems

et al. 2006

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The spatial structure of (Z ) (5R) methyl 2 (4 phenylbenzylidene)cyclohexanone prepared by photochemical isomerization of the E isomer was studied by analyzing the magnitudes and temperature dependence of the proton spin spin coupling constants obtained by 1 H NMR spectroscopy and the results of molecular modeling using semiempirical quantum chemical AM1 and PM3 methods and the density functional theory (DFT). Comparison of the results obtained for the Z and E isomers shows that in both cases the conformational equilibrium for both isomers is characterized by significant preference of the chair conformer having an equatorial methyl group, namely, -∆H (chair a chair e) = 1.98-2.12 and 1.36-1.54 kcal mole -1 for the Z and E isomers, respectively. Distinctions in the non planar ity of the enone fragment and cyclohexanone ring in the Z and E isomers under study following from the results of mathematical modeling were confirmed by the experimental values of the geminal spin spin coupling constants of protons of the methylene groups in α,α´ positions with respect to the enone group. Quantum chemical calculations of the Z isomer revealed the existence of intramolecular hydrogen bond between the carbonyl oxygen and the nearest aromatic proton in ortho position of the benzene ring. Possible reasons for different helical twisting power of (Z ) (5R) methyl 2 (4 phenylbenzylidene)cyclohexanone and the E and Z arylidene derivatives of 1R,4R isomenthone in the mesophase are discussed based on the results of molecular structure studies for these compounds.Key words: (Z ) and (E) (5R) methyl 2 (4 phenylbenzylidene)cyclohexanone, confor mational state, 1 H NMR spectroscopy, quantum chemical calculations, intramolecular hydro gen bond. Chiral α,β unsaturated ketones with six membered ring preset s cis configuration of enone fragment and a Z or E configuration relative to the double bond are of considerable interest as components of liquid crystalline (LC) systems with induced helical supramolecular order ing. 1-4 Photoinduced effects in LC compositions, which accompany a reversible photochemical E-Z isomeriza tion typical of these compounds, 5-9 strongly depend on the nature of both the nematic solvent and, especially, the chiral additive (CA), although the reasons for this depen dence are unclear.Photoactive CA include, in particular, 2 arylidene de rivatives of (1R,4R) isomenthone ((3R,6R) 6 isopropyl 3 methylcyclohexanone) 1*, which were studied in detail earlier. 5,6,10,11 UV Irradiation of E isomers in both iso tropic organic solvents 5,10 and LC media 5,11 causes a highly efficient E-Z photoisomerization. A feature of this photochemical transformation consists in a higher quan tum yield of the direct reaction compared to that of the reverse reaction. This predetermines a much higher pro portion of the Z isomer in the photostationary state. 10 An important macroscopic manifestation of this photo transformation in doped LC compositions is an increase in the pitch of the supramolecular helix (P), i.e., its un twisting. 5,11 A n...

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Section: Methodsmentioning

confidence: 99%

Structure of (Z)-(5R)-methyl-2-(4-phenylbenzylidene)cyclohexanone as chiral component of liquid-crystalline systems

et al. 2006

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“…1-Methyl-closo-1,2-C 2 B 10 H 11 (4) was obtained from Katchem Ltd, Methylaluminoxane (MAO, 10 wt% solution in toluene) was provided by Sigma-Aldrich. ð½Na C ½1-Me-2-ððCH 2 Þ 4 NH-Þ-1; 2-C 2 B 9 H K 10 ½OEtÞ n ðSWCNTÞ (1) [11] and Ni(PPh 3 ) 2 Cl 2 (2) [12] were prepared according to literature. FT-IR spectra were measured using a BIO-RAD spectrophotometer with KBr pellets or organic solvent films.…”

Section: General Commentsmentioning

confidence: 99%

Syntheses and catalytic activities of single-wall carbon nanotubes-supported nickel (II) metallacarboranes for olefin polymerization

Zhu

Sia

Carpenter

et al. 2006

Journal of Physics and Chemistry of Solids

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“…Nickel(0), which is produced in situ by the reaction of Ni(PPh 3 ) 2 Cl 2 [18] or even better Ni(PPh 3 ) 2 Br 2 [19] with metallic zinc, is able to couple two aromatic halogenides, preferably bromides, though some chlorides [20] are also reported (Scheme 3).…”

Section: Nickel-mediated Reactionsmentioning

confidence: 99%

The Higher Oligopyridines and their Metal Complexes

Fallahpour¹

2006

COS

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Preparation, Spectra and Electronic Structures of Tetrahedral Nickel(II) Complexes Containing Triphenylphosphine and Halide Ions as Ligands

Cited by 132 publications

References 0 publications

Structure of (Z)-(5R)-methyl-2-(4-phenylbenzylidene)cyclohexanone as chiral component of liquid-crystalline systems

Structure of (Z)-(5R)-methyl-2-(4-phenylbenzylidene)cyclohexanone as chiral component of liquid-crystalline systems

Syntheses and catalytic activities of single-wall carbon nanotubes-supported nickel (II) metallacarboranes for olefin polymerization

The Higher Oligopyridines and their Metal Complexes

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