Syntheses and electrochemical characterization of heteroleptic cyclopentadienyl-bis(dithiolene) complexes of niobium and tantalum

2000 ◽  
Vol 78 (12) ◽  
pp. 1570-1574 ◽  
Author(s):  
I V Jourdain ◽  
F Guyon
Keyword(s):  
Cyclic Voltammetry ◽  
Key Words ◽  
General Formula ◽  
Nmr Spectra ◽  
Variable Temperature ◽  
Redox Properties ◽  
Temperature Dependent ◽  
Oxidation Processes ◽  
H Nmr

Diamagnetic niobium and tantalum complexes of general formula [M(η5-C5Me5)(dithiolene)2] have been prepared (M = Nb, dithiolene = dddt2– (5,6-dihydro-1,4dithiine-2,3-dithiolate) (1); M = Ta, dithiolene = dddt2– (2); M = Nb, dithiolene = dddt2– and dmit2– (1,3-dithiole-2-thione-4,5-dithiolate) (3)). All these complexes exhibit temperature-dependent 1H NMR spectra which result from a fluxional behavior of the dithiolene ligands. Their redox properties have been investigated by cyclic voltammetry and reversible oxidation processes involving the dithiolene ligands have been evidenced for the complexes 1 and 2.Key words: niobium, tantalum, dithiolene, voltammetry cyclic, variable-temperature 1H NMR.

Phenylsilane dehydrocoupling and addition to styrene catalyzed by (R-indenyl)Ni(phosphine)(methyl) complexes

2009 ◽  
Vol 87 (1) ◽  
pp. 280-287 ◽  
Author(s):  
Yaofeng Chen ◽  
Davit Zargarian
Keyword(s):  
Solid State ◽  
Nmr Spectra ◽  
Variable Temperature ◽  
Structural Parameters ◽  
Catalytic Cycle ◽  
Synthesis And Characterization ◽  
H Nmr ◽  
Solid State Structures ◽  
Indenyl Complexes

This report describes the synthesis and characterization of the Ni–Me complexes (R-indenyl)Ni(PR′3)Me (R = 1-i-Pr, 1-SiMe3, and 1,3-(SiMe3)2; R′= Me, Ph) and outlines their catalytic reactivities in the dehydrogenative oligomerization of PhSiH3 and its addition to styrene in the absence of initiators/activators. Observation of higher hydrosilylation activities for PPh3-based compounds featuring bulky substituents on the indenyl ligand confirms earlier suggestions that phosphine dissociation is an important component of the catalytic cycle for this reaction. In contrast, oligomerization of PhSiH3 is more facile with PMe3-based precursors and independent of the steric bulk of the indenyl ligand, implying that this reaction does not involve phosphine dissociation. These conclusions are consistent with the variable-temperature 1H NMR spectra of {1,3,-(SiMe3)2-indenyl}Ni(PR′3)Me and various structural parameters observed in the solid-state structures of {1,3,-(SiMe3)2-indenyl}Ni(PPh3)Me, {1,3,-(SiMe3)2-indenyl}Ni(PMe3)Cl, and {1-SiMe3-indenyl}Ni(PMe3)Me.Key words: nickel-indenyl complexes, hydrosilylation, hydrosilane oligomerization.

Rotationsbarriere der Endgruppen bei Poly- methinoxonolen verschiedener Kettenlänge / Rotation Barrier of the End Groups of Polymethine Oxonols with Different Chain Lengths

1976 ◽  
Vol 31 (8) ◽  
pp. 1017-1018 ◽  
Author(s):  
H. Oehling ◽  
F. Baer
Keyword(s):  
Nmr Spectra ◽  
Rotation Barrier ◽  
Free Enthalpy ◽  
Temperature Dependent ◽  
Restricted Rotation ◽  
H Nmr ◽  
Enthalpy Of Activation ◽  
End Groups ◽  
Electron Contribution ◽  
Chain Lengths

Abstract Polymethine oxonols show temperature dependent 1H-NMR-spectra because of restricted rotation of the end groups. The dependence of the value of the corresponding free enthalpy of activation AGt on the length of the poly-methine chain can be explained by the change of the π-electron contribution to ⊿G≠.

Electrochemically Synthesis and Characterization of Copolymers Based on 1, 4-Diethoxybenzene and 3, 4-Ethylenedioxythiophene

2011 ◽  
Vol 335-336 ◽  
pp. 989-993
Author(s):  
Mi Ouyang ◽  
Zhen Wei Yu ◽  
Yi Xu ◽  
Yu Jian Zhang ◽  
Cheng Zhang
Keyword(s):  
Cyclic Voltammetry ◽  
Ir Spectroscopy ◽  
Feed Ratio ◽  
Synthesis And Characterization ◽  
Monomer Mixture ◽  
Long Wavelength ◽  
H Nmr ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Copolymers based on 1, 4-diethoxybenzene (DEB) and 3, 4-ethylenedioxythiophene (EDOT) were electrochemically synthesized and characterized. The structures of the copolymers were established by 1H NMR and FT-IR spectroscopy. The results indicated the final product was a copolymer instead of a blend or a composite. The physical properties were systematically investigated by cyclic voltammetry, UV-vis absorption and fluorescence. The PL maximum of copolymers presented obviously red-shift to long wavelength as the feed ratio of EDOT in monomer mixture increased.

Chlormethylchlorphosphane mit sperrigen Substituenten -Synthese und reduktive Enthalogenierung mit Fe2(CO)9 / Bulky Chloromethylchlorophosphines -Syntheses and Reductive Dehalogenation with Fe2 (CO)9

1997 ◽  
Vol 52 (8) ◽  
pp. 883-894 ◽  
Author(s):  
Jörg Fischer ◽  
Peter Machnitzki ◽  
Othmar Stelzer
Keyword(s):  
Nmr Spectra ◽  
Elevated Temperatures ◽  
Reductive Dehalogenation ◽  
Molar Ratio ◽  
Carbonyl Complex ◽  
Temperature Dependent ◽  
Phenyl Derivative ◽  
H Nmr ◽  
Halogen Exchange ◽  
Stage Synthesis

Chloromethylchlorophosphines R(Cl)P-CH2-Cl (R = C6H11, sec-C4H9, 2,4,6-R′3C6H2; R′ = tBu, iPr) with bulky substituents (1a - 1d) have been prepared by treatment of Cl2P-CH2-Cl with organolithium compounds RLi (R = 2,4,6-R′3C6H2) or Grignard reagents RMgX (R = C6H11, sec-C4H9). For the less bulky phenyl derivative Ph(Cl)P-CH2-Cl (1i) a protected group two stage synthesis has been developed employing Et2N(Cl)P-CH2-Cl as an intermediate. Si-N cleavage reactions between Cl2P-CH2-Cl and R2N-SiMe3 or nucleophilic substitution with Ph2NH yield the amino derivatives R′2N(Cl)P-CH2-Cl (R′ = Ph, Et, iPr) (1e, 1g, 1h). The chloromethylbromophosphines R(Br)P-CH2-Cl (R = Br, C6H11) have been obtained by halogen exchange in 1 and 1a with MgBr2 etherate. 1a, 1e, 1g and 1h exist preferably in an antiperiplanar conformation with respect to the P-C(H2) bond as inferred from the analysis of the 1H(CH2)-NMR spectra. Temperature dependent 1H and 13C {1H} NMR spectra indicate restricted rotational processes in 1h. On reaction of 2a with Fe2(CO)9 the η2,μ3-phosphaalkene cluster 3 is obtained, while with 2b (R = 2,4,6-iPr3C6H2) the μ3-phosphinidene cluster 4 is formed. Reductive dehalogenation of 1c (R = 2,4,6-tBu3C6H2) affords the phosphaalkene complex 6 in addition to the 2,3-dihydrobenzo[b]phosphole complex 5. Treatment of the iron carbonyl complex 7c with Fe2(CO)9 in a 1:1 molar ratio at elevated temperatures leads to a novel μ2-phosphido complex 7b with an ortho-metallated Ph2N substituent.

Zum ambidenten Charakter des Cyanotrihydroborat-Liganden in Uran(IV)-Organylen / On the Ambident Nature of the Cyanotrihydroborate Ligand in Organouranium(IV) Complexes

1983 ◽  
Vol 38 (11) ◽  
pp. 1369-1374 ◽  
Author(s):  
R. Dieter Fischer ◽  
Kenan Yünlü
Keyword(s):  
Solid State ◽  
Nmr Spectra ◽  
Colour Change ◽  
Metal Coordination ◽  
Temperature Dependent ◽  
H Nmr ◽  
Trigonal Bipyramidal ◽  
Oligomeric Complex

Both the acceptedly oligomeric complex [(C5H5)3U(μ-NCBH3)]n (1) and its hitherto unknown, appreciably more soluble and volatile homologue, [(CH3C5H4)3U(μ-NCBH3)]n (2), display NIR/VIS spectra typical of trigonal bipyramidal (tbp) metal coordination in the solid state, but of pseudotetrahedral (ψ-Td) coordination e.g. in CH2CI2 and C6H5CH3 solution. The 1H NMR spectra of 2 in these non coordinating solvents can be best explained in terms of temperature dependent equilibria involving the two rapidly interconverting ψ-Td-isomers (CH3C5H4)3U(η3-H3BCN) and (CH3C5H4)3UNCBH3. A reversible colour change: green ⇋ brown at 130-150 °C also suggests the facile rupture of U-H and U-N bonds, respectively, in thermally excited, polycrystalline (2).

scholarly journals Stickstoffverbindungen von Elementen der dritten Hauptgruppe mit intra- und intermolekularen Donor-Akzeptor-Bindungen, V [1]. Spezielle Gallium- und Indiumamide mit Alkoxogruppen / Nitrogen Compounds of Elements of the Third Main Group with Intra- and Intermolecular Donor Acceptor Bonds, V [1]. Special Gallium and Indium Amides with Alkoxo Groups

1988 ◽  
Vol 43 (5) ◽  
pp. 505-512 ◽  
Author(s):  
M. Veith ◽  
J. Pöhlmann
Keyword(s):  
Metal Atom ◽  
Nmr Spectra ◽  
Main Group ◽  
Nitrogen Compounds ◽  
Temperature Dependent ◽  
H Nmr ◽  
The Third ◽  
Donor Acceptor ◽  
Molecular Compounds ◽  
Chelating Effect

AbstractThe lithium alkoxoamidosilane (Me2Si(OtBu)(NtBu)Li)2 (4) and its trimethyltin derivative Me2Si(OtBu)(NtBu)SnMe3 (7) have been used, to introduce the ligand Me2Si(OtBu)(NtBu) = L into molecular compounds of gallium and indium. The following molecules were synthesized: L-M(Me)Cl (M = Ga (5), In (6)), L-InMe2 (8), L-InX2 (X = Cl (9), Br (10)), L2InX (X = Cl (11), Br (12)) and L2Ga2Cl2 (22). The ligand L is assumed to chelate the metal atom on the basis of temperature dependent 1H NMR spectra. The chelating effect is more pronounced in the gallium derivatives than in the indium analogues. Equilibria between L2InX/InX3 and LInX2 have been observed in diethylether solutions. No metal(I) derivatives LGa or LIn could be isolated. L2Ga2Cl2 (22), formally containing gallium(ll), can be sublimed without decomposition at 110 °C in vacuo.

Nuclear magnetic resonance studies of the methylammonium hexahalotellurates

1992 ◽  
Vol 70 (3) ◽  
pp. 849-855 ◽  
Author(s):  
Mark R. MacIntosh ◽  
Marco L. H. Gruwel ◽  
Katherine N. Robertson ◽  
Roderick E. Wasylishen
Keyword(s):  
Line Shape ◽  
Nmr Spectra ◽  
Room Temperature ◽  
Solid Phase ◽  
Variable Temperature ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
H Nmr ◽  
Nmr Study ◽  
Correlated Motion

A 2H and 14N NMR study of the solid methylammonium hexahalotellurates, (MA)2TeX6 (MA = CH3ND3+ or CD3NH3+, X = Cl, Br, and I), has been undertaken to characterize the dynamics of the methylammonium (MA) ion as a function of temperature. At room temperature, the MA ion in the hexachlorotellurate (solid II) is confined to C3 jumps about the C—N axis while a small angle libration of the C—N axis is occurring. In the room temperature phase, solid I, of (MA)2TeBr6 and (MA)2TeI6 the MA ions are performing overall reorientations on the ps time scale, averaging the 2H nuclear quadrupolar interactions to zero. Variable temperature 2H NMR spin-lattice relaxation times, T1, indicate an activation energy, EA, for "isotropic" reorientations of the CH3ND3+ ion of 5.2 ± 0.5 and 2.6 ± 0.3 kJ mol−1 for X = Br and I, respectively. Deuterium T1 values for C-deuterated MA ion in the hexaiodotellurate indicate an EA for whole-ion reorientation of 3.1 ± 0.3 kJ mol−1. At any given temperature, the correlation time, τc, derived from the T1 results was found to be the same for the two deuterium-labelled hexaiodotellurates. The similarity of both the EA and the τc values implies correlated motion of the methyl and ammonium groups. The 14N T1 results for solid I of (MA)2TeI6 indicate that C—N axis motions, with an EA = 5.6 ± 0.6 kJ mol−1, are more hindered than N—D or C—D bond dynamics. The 2H NMR spectra for (MA)2TeI6 (solid II) and (MA)2TeBr6 (solids II, III, and IV) are characterized by a Pake doublet line shape. The measured peak-to-peak splittings are less than what is predicted by C3 motion about the molecular symmetry axis. It is possible to model these line shapes by postulating that C3 rotations of the methyl and ammonium groups occur as the C—N axis librates in an effective cone about the position of the static molecular axis. For (CH3ND3)2TeBr6 and (CD3NH3)3TeBr6 the peak-to-peak splittings in the 2H NMR spectra were measured as a function of temperature in solid phases II, III, and IV and were found to be similar. Finally, the 2H NMR line shape relaxation for (MA)2TeBr6 (solid III) displays an orientation dependence indicating that rotations about the C—N axis are discrete rather than diffusive in nature. For solid phase II of (MA)2TeCl6, the line shape is observed to relax isotropically, implying that continuous C3 rotations are taking place. Keywords: 2H and 14N NMR, methylammonium hexahalotellurates, molecular motion.

scholarly journals Preparation and Characterization of Styrene Bearing Diethanolamine Side Group, Styrene Copolymer Systems, and Their Metal Complexes

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Aslışah Açıkses ◽  
Necmittin Çömez ◽  
Fatih Biryan
Keyword(s):  
Free Radical ◽  
Electrical Properties ◽  
Metal Complexes ◽  
Nmr Spectra ◽  
Side Group ◽  
Conductivity Measurements ◽  
H Nmr ◽  
Ft Ir ◽  
Polymerization Method

The two copolymer systems of styrene bearing diethanol amine side group and styrene were prepared by free radical polymerization method at 60°C in presence of 1,4-dioxane as solvent and AIBN as initiator. Their metal complexes were prepared by reaction of the copolymer used as ligand P(DEAMSt-co-St)L′′ and Ni(II) and Co(II) metal ions, which was carried out in presence of ethanol and NaOH at 65°C for 48 h in pH = 7.5. The structures of the copolymers used as ligand and metal complexes were identified by FT-IR, 1H-NMR spectra, and elemental analysis. The properties of the copolymers used as ligand and metal complexes were characterized by SEM-EDX, AAS, DSC, TGA, and DTA techniques. Then, the electrical properties of the copolymers and metal complexes were examined as a function of the temperature and frequency, and the activation energies (Ea) were estimated with conductivity measurements.

Synthesis and characterization of an homologous series of bis(amido)diazadipnictetidines (Pnict = P, As, Sb, Bi)

2001 ◽  
Vol 79 (3) ◽  
pp. 342-348 ◽  
Author(s):  
Neil Burford ◽  
T Stanley Cameron ◽  
Kim-Chung Lam ◽  
Daren J LeBlanc ◽  
Charles LB Macdonald ◽  
...  
Keyword(s):  
Key Words ◽  
General Formula ◽  
Homologous Series ◽  
Spectroscopic Characterization ◽  
Structural Features ◽  
Synthesis And Characterization ◽  
General Reaction ◽  
Coordinative Unsaturation

Spectroscopic and structural features are presented for the first homologous series of diazadipnictetidines, which have the general formula [DipNPnN(H)Dip]2 (Pn = P, As, Sb, Bi; Dip = 2,6-diisopropylphenyl). The compounds are obtained from a general reaction of the corresponding halopnictine with excess LiN(H)Dip, which was previously reported for [DipNBiN(H)Dip]2. However, isolation is improved by the introduction of LiN(H)-t-Bu (at the appropriate stoichiometry) following the addition of LiN(H)Dip. The intermediate steric presence of the Dip substituent is suitable to support the heterocatenate framework for all homologues. This is in contrast to the small substituents (e.g. alkyl), which enable both bis- and tris-amination, and the larger substituent (Mes* = tri-tert-butylphenyl), which can impose coordinative unsaturation (aminoiminopnictine) for the smaller congeners (P and As).Key words: phosphorus, arsenic, antimony, bismuth, phosphazanes, phosphetidines, synthesis, structures, spectroscopic characterization.

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