Indirect nuclear spin-spin coupling in tetrachlorotetraborane(4) and halogenated polyhedral phospha- and arsaboranes

Keller, W.; Haubold, W.; Wrackmeyer, Bernd

doi:10.1002/(sici)1097-458x(199908)37:8<545::aid-mrc496>3.0.co;2-e

Cited by 12 publications

(11 citation statements)

References 32 publications

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“…1.). Similar behaviour of the boron signals were observed for (5) and (6). In conjunction with the efficient background suppression of DEPTH, the peak heights of the resonances of (4), (5) and (6) drop about 21%, 24% and 30%, respectively.…”

Section: Bsupporting

confidence: 72%

“…Compound (2) has very sharp 11 B (14.3 Hz at half-height), but even sharper 10 B (8.0 Hz at half-height) resonance. The S/N ratio and T 1 relaxation of (2), (5) and (6) are given in Table 2 to illustrate the effect of relaxation with experimental data. As the efficiency of quadrupolar relaxation increases, the S/N advantage of 11 B reduces.…”

Section: Resultsmentioning

confidence: 99%

“…S1.). These compounds have significantly sharper resonances as compared with (4)(5)(6)(7)(8) in conjunction with their much longer relaxation times ( Table 3). The boron background is usually not visible next to (Fig.…”

Section: Bmentioning

confidence: 99%

“…Indeed, 10 B NMR applications are limited to special cases, e.g. measurement of J ‐couplings, mechanistic investigations based on 10 B labelling, relaxation studies, boron neutron capture therapy of cancer and the solid‐state NMR of boron doped diamond.…”

Section: Introductionmentioning

confidence: 99%

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Background‐free solution boron NMR spectroscopy

Király

2012

Magnetic Reson in Chemistry

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The appearance of background signals arising from the NMR probe and tube is a well-known problem of boron NMR spectroscopy. Background suppression may be achieved by using DEPTH, which increases the signal-to-background (S/B) ratio. Although, the quality of such spectra is often adequate, but in the case of rapid relaxation broadened resonances (T(1) < 1 ms), the residual background signals may still hamper the interpretation of the spectra. It was observed that the background signals are practically invisible in solution (10) B NMR. The unusual isotopic effect on the (S/B) ratio was interpreted as an inherent consequence of the integer versus half-integer spin of (10) B and (11) B, respectively. The practicability of (10/11) B NMR was compared for a selected set of boron compounds covering the typical range of (S/B) ratio. The application of (11) B is more favourable than (10) B as long as it is possible to achieve the desired spectral quality by using DEPTH. Otherwise, the 'background-free' appearance of (10) B NMR spectra makes (10) B a reasonable alternative of (11) B DEPTH. This was found typical for compounds having relaxation broadened resonances. The variable temperature (VT) NMR study of an adduct formation process was also presented here as an example of the advantage of (10) B over (11) B.

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Section: Bsupporting

confidence: 72%

Section: Resultsmentioning

confidence: 99%

Section: Bmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Background‐free solution boron NMR spectroscopy

Király

2012

Magnetic Reson in Chemistry

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“…The 31 P resonances of the isomers containing the Fe−P bond ( 1a , 1b , 1d , and 1e ) fall within a range of ca. δ = +20 to −45 ppm, while the 31 P(10) resonance in 1c is shifted to low frequency (δ

_{^{31} P}

= −166 ppm), to a range typical of phosphorus in polyhedral boranes with a closo structure 10. Therefore, the 31 P NMR signals at higher frequencies in the range of δ = +20 to −55 ppm are a consequence of Fe−P bonding.…”

Section: Resultsmentioning

confidence: 94%

Phosphadicarbaborane Analogues of Ferrocene: New Isomers of [closo‐(η⁵‐C₅H₅)FePC₂B₈H₁₀]

et al. 2003

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Thermal isomerisation of the ferraphosphadicarbaborane [1‐Cp‐closo‐1,2,4,5‐FePC2B8H10] (1a; Cp = η5‐C5H5−) at elevated temperatures (180−350 °C) leads to the formation of three new isomeric complexes. These were characterized by multinuclear (1H, 11B, 31P, and 13C) NMR spectroscopy and mass spectrometry as [1‐Cp‐closo‐1,2,3,8‐FePC2B8H10] (1b), [1‐Cp‐closo‐1,10,2,4‐FePC2B8H10] (1c), and closo‐[1,2,4,10‐FePC2B8H10] (1d). The formation of 1b is accompanied by an unusual agglomeration of the P and C heteroatoms. Complexes 1b and 1c have also been isolated as side products from the direct reaction between nido‐[7,8,9‐PC2B8H11] (2) and [CpFe(CO)2]2 in refluxing mesitylene, and 1a and 1b from the pyrolysis of [7‐Fp‐(η1‐nido‐7,9,10‐PC2B8H10)] [3; Fp = CpFe(CO)2] at 350 °C. NMR intercomparisons of all five [1‐Cp‐closo‐FePC2B8H10] isomers thus far isolated have been made. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Syntheses of Halogenated Polyhedral Phosphaboranes: Crystal Structure of conjuncto‐3,3′‐(closo‐1,2‐P₂B₄Br₃)₂

Keller

2017

Zeitschrift anorg allge chemie

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Co‐pyrolysis of B2Br4 with PBr3 at 480 °C gave, in addition to the main product closo‐1,2‐P2B4Br4, conjuncto‐3,3′‐(1,2‐P2B4Br3)2 (1) and the twelve‐vertex closo‐1,7‐P2B10Br10 (2), both in low yields. X‐ray structure determination for 1 [triclinic, space‐group P1 with a = 7.220(2) Å, b = 7.232(2) Å, c = 8.5839(15) Å, α = 97.213(15)°, β = 96.81(2)°, γ = 94.07(2)° and Z = 1] confirmed that 1 adopts a structure consisting of two symmetrically boron–boron linked distorted octahedra with the bridging boron atoms in the 3,3′‐positions and the phosphorus atoms in the 1,2‐positions. The intercluster 2e/2c B–B bond length is 1.61(3) Å. The shortest boron–boron bond within the cluster framework is 1.68(2) Å located between the boron atoms antipodal to the phosphorus atoms. The icosahedral phosphaborane 2 was characterized by 11B‐11B COSY NMR spectroscopy showing cross peaks indicative for the isomer with the phosphorus atoms in 1,7‐positions. Both the X‐ray data of 1 and the NMR spectroscopic data of 1 and 2 give further evidence for the influence of an antipodal effect of heteroatoms to cross‐cage boron atoms and, vice versa, of an additional shielding of the phosphorus atoms caused by B‐Hal substitution at the boron positions trans to phosphorus.

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Indirect nuclear spin-spin coupling in tetrachlorotetraborane(4) and halogenated polyhedral phospha- and arsaboranes

Cited by 12 publications

References 32 publications

Background‐free solution boron NMR spectroscopy

Background‐free solution boron NMR spectroscopy

Phosphadicarbaborane Analogues of Ferrocene: New Isomers of [closo‐(η⁵‐C₅H₅)FePC₂B₈H₁₀]

Syntheses of Halogenated Polyhedral Phosphaboranes: Crystal Structure of conjuncto‐3,3′‐(closo‐1,2‐P₂B₄Br₃)₂

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Indirect nuclear spin-spin coupling in tetrachlorotetraborane(4) and halogenated polyhedral phospha- and arsaboranes

Cited by 12 publications

References 32 publications

Background‐free solution boron NMR spectroscopy

Background‐free solution boron NMR spectroscopy

Phosphadicarbaborane Analogues of Ferrocene: New Isomers of [closo‐(η5‐C5H5)FePC2B8H10]

Syntheses of Halogenated Polyhedral Phosphaboranes: Crystal Structure of conjuncto‐3,3′‐(closo‐1,2‐P2B4Br3)2

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Phosphadicarbaborane Analogues of Ferrocene: New Isomers of [closo‐(η⁵‐C₅H₅)FePC₂B₈H₁₀]

Syntheses of Halogenated Polyhedral Phosphaboranes: Crystal Structure of conjuncto‐3,3′‐(closo‐1,2‐P₂B₄Br₃)₂