35Cl, 81Br and 127I NQR spectra of cyclopentadienyltitanium halides

Bryukhova, E. V.; Семин, Г. К.; ALIMOV, I. M.; Nesmeyanov, A. N.; Nogina, O. V.; Dubovitsky, V.A.; Кузнецов, С. И.

doi:10.1016/s0022-328x(00)84839-1

Cited by 13 publications

(9 citation statements)

References 9 publications

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“…The difference between values of C Q in these two species must therefore arise from differences in Ti-Cl covalent bonding. In this light, Bryukhova and co-workers 44,45 have previously ascribed the smaller C Q in CpTiCl 3 to increased Ti-Cl π bonding in comparison with that in Cp 2 TiCl 2. This hypothesis is further discussed in Quantum-Chemical Calculations.…”

Section: Resultsmentioning

confidence: 98%

“…Bryukhova and co-workers 44,45 have previously hypothesized that increased Ti-Cl π bonding leads to a decrease in the observed 35/37 Cl EFGs. This hypothesis was used to explain the large decrease in C Q observed when the 35 Cl NQR data from CpTiCl 3 and Cp 2 TiCl 2 were compared.…”

Section: Resultsmentioning

confidence: 99%

“…complex and others via NQR spectroscopy. 44,45 The value of ν Q is related to the C Q value for an I ) 3 / 2 nucleus by the expression…”

Section: Resultsmentioning

confidence: 99%

“…To date, the largest value of C Q measured by 35 Cl SSNMR on a powdered sample is that of aluminum trichloride (C Q ) 9.4 MHz), 43 which has a 35 Cl powder pattern with a breadth of over 250 kHz at 14.1 T. 35 Cl quadrupolar parameters for halogenated transition-metal metallocenes fall into this intermediate regime. For instance, 35 Cl NQR spectra acquired by Bryukhova and co-workers 44,45 revealed values of C Q ranging from ∼16 MHz in CpTiCl 3 to 24 MHz in Cp 2 TiCl 2 , corresponding to 35 Cl SSNMR powder patterns 1-3 MHz in breadth at moderate magnetic field strengths (e.g., 9.4 T). The extreme breadths of such 35 Cl powder patterns necessitates the use of frequency-stepped NMR techniques, [46][47][48][49][50][51][52][53] where separate spin echoes are acquired at evenly spaced transmitter frequencies.…”

Section: Introductionmentioning

confidence: 99%

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Solid-State Chlorine NMR of Group IV Transition Metal Organometallic Complexes

et al. 2009

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Static solid-state (35)Cl (I = (3)/(2)) NMR spectra of the organometallic compounds Cp(2)TiCl(2), CpTiCl(3), Cp(2)ZrCl(2), Cp(2)HfCl(2), Cp*(2)ZrCl(2), CpZrCl(3), Cp*ZrCl(3), Cp(2)ZrMeCl, (Cp(2)ZrCl)(2)mu-O, and Cp(2)ZrHCl (Schwartz's reagent) have been acquired at 9.4 T with the quadrupolar Carr-Purcell Meiboom-Gill (QCPMG) sequence in a piecewise manner. Spectra of several samples have also been acquired at 21.1 T. The electric field gradient (EFG) tensor parameters, the quadrupolar coupling constant (C(Q)) and quadrupolar asymmetry parameter (eta(Q)), are readily extracted from analytical simulations of the spectra. The (35)Cl EFG and chemical-shift tensor parameters are demonstrated to be sensitive probes of metallocene structure and allow for differentiation of monomeric and oligomeric structures. First-principles calculations of the (35)Cl EFG parameters successfully reproduce the experimental values and trends. The origin of the observed values of C(Q)((35)Cl) are further examined with natural localized molecular orbital (NLMO) analyses. The combination of experimental and theoretical methods applied to the model compounds are employed to structurally characterize Schwartz's reagent (Cp(2)ZrHCl), for which a crystal structure is unavailable. Aside from a few select examples of single-crystal NMR spectra, this is the first reported application of solid-state (35)Cl NMR spectroscopy to molecules with covalently bound chlorine atoms. It is anticipated that the methodology outlined herein will find application in the structural characterization of a wide variety of chlorine-containing transition-metal and main-group systems.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

“…complex and others via NQR spectroscopy. 44,45 The value of ν Q is related to the C Q value for an I ) 3 / 2 nucleus by the expression…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Solid-State Chlorine NMR of Group IV Transition Metal Organometallic Complexes

et al. 2009

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“…This follows precedence established in previous work on organometallics. 18,22 Similar reasoning was recently used in analogous NMR studies of Ti organometallics. 15,16,19,20 In the present study the NQR spectra were recorded using a purpose built experimental Fourier transform nuclear quadrupole resonance (FT-NQR) spectrometer constructed in our laboratory.…”

Section: Nuclear Quadrupole Resonancementioning

confidence: 66%

Combining Fourier transform nuclear quadrupole resonance (FT-NQR) spectroscopy and mass spectrometry (MS) to study the electronic structure of titanocene dichlorides

Kubišta

Civiš

Španěl

et al. 2012

Analyst

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A combination of nuclear quadrupole resonance spectroscopy (NQR) and mass spectrometry (MS) has been used to observe trends in electronic structure in three titanocenes: bis(cyclopentadienyl) titanium dichloride (η(5)-C(5)H(5))(2)TiCl(2), bis(pentamethylcyclopentadienyl) titanium dichloride (η(5)-C(5)(CH(3))(5))(2)TiCl(2) and dimethylsilylene-bridged ansa bis(cyclopentadienyl) titanium dichloride Si(CH(3))(2)(η(5)-C(5)H(5))(2)TiCl(2). Using MS, electron ionisation mass spectra of these compounds are presented within the context of the entire homologous series with one to five methyl groups on each cyclopentadienyl ligand. A dedicated NQR spectrometer was constructed for this study with a sensitivity sufficient to precisely determine the NQR resonant frequency of (35)Cl atoms using 3 g samples of these titanocenes. The observed frequencies are thus 11.784, 11.930 and 10.863 MHz at 298 K. The results demonstrate that NQR using a relatively simple apparatus can be used as a sensitive and cost effective probe into the molecular structure of organometallic chlorides, which complements the information inferred from the mass spectra.

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Nuclear Quadrupole Resonance (NQR) Spectroscopy

Wulfsberg

2005

Encyclopedia of Inorganic Chemistry

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The article concerns the usefulness of nuclear quadrupole resonance (NQR) spectroscopy in inorganic and organometallic chemistry. NQR‐active nuclei have spin I ≥ 1; those of high enough abundance to be commonly useful are found in the odd‐numbered groups of the periodic table. These are tabulated and examples given for each. The number of NQR frequencies observed in a solid‐state compound reflects the number of chemically different quadrupolar atoms in the compound and also the number of crystallographically inequivalent atoms; changes in the latter may indicate phase transitions or different polymorphs of a given compound. More commonly, one uses average NQR frequencies for chemically different atoms, and from these average frequencies, derives atomic parameters such as populations of valence orbitals, partial ionic charges, π‐bond orders, and covalent bond orders of the quadrupolar atom. The article mainly reviews selected applications of halogen ( 35 Cl, 79, 81 Br, 127 I) NQR to specific bonding questions in inorganic chemistry, and divides these according to whether the halogen or other atoms are (a) single bonded, (b) single bonded but with secondary bonds with other atoms, or (c) bonded to several atoms. For singly bonded atoms, the applications reviewed include (a1) relativistic effects, (a2) effects of nearby ionic charges on haloacetate ions, (a3) the contrasting effects of nearby ionic charges on halometallate ions, (a4) effects of intramolecular partial charges on chlorines in organosilicon compounds, (a5) cis‐and trans‐ ligand effects in substituted halometallate complexes, and (a6) interpretations of multicentered bonding in trihalide ions. Secondary bonding of single‐bonded halogen atoms are reviewed particularly in the cases of (b1) halocarbons as ligands, (b2) chloroacetates and chlorophenolates as chlorine‐donor ligands, and (b3) in salts of weakly coordinated halogenated anions. Finally, some illustrations are given of NQR studies of central multicoordinated atoms (for example, transition‐metal atoms in complexes).

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35Cl, 81Br and 127I NQR spectra of cyclopentadienyltitanium halides

Cited by 13 publications

References 9 publications

Solid-State Chlorine NMR of Group IV Transition Metal Organometallic Complexes

Solid-State Chlorine NMR of Group IV Transition Metal Organometallic Complexes

Combining Fourier transform nuclear quadrupole resonance (FT-NQR) spectroscopy and mass spectrometry (MS) to study the electronic structure of titanocene dichlorides

Nuclear Quadrupole Resonance (NQR) Spectroscopy

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