Applications of 29Si NMR Parameters

Wrackmeyer, Bernd

doi:10.1016/s0066-4103(05)57001-7

Cited by 47 publications

(22 citation statements)

References 379 publications

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“…The silole 7c shows a 29 Si NMR signal at d = + + 9.8, which occurs downfield from the corresponding 29 Si NMR resonance of the starting material 1c (d = À39.4). [26] It features two sets of o-, p-and m-C 6 F 5 19 F NMR signals in a 2:1 ratio, namely of the Lewis acidic -BA C H T U N G T R E N N U N G (C 6 F 5 ) 2 substituent, with a typically rather large DdA C H T U N G T R E N N U N G (m/p) separation [27] and the signals of the single carbon bound C 6 F 5 group. The 13 C NMR signals of the four "quarternary" ring carbon atoms C2 to C5 were located at d = 152.3, 136.7, 161.9 (adjacent to B), and 165.5.…”

Section: Resultsmentioning

confidence: 99%

Reaction of Bis(alkynyl)silanes with Tris(pentafluorophenyl)borane: Synthesis of Bulky Silole Derivatives by Means of 1,1‐Carboboration under Mild Reaction Conditions

et al. 2009

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)diphenylsilane (1d) with tris(pentafluorophenyl)-borane gave the corresponding boryl-substituted silole derivative (7d) featuring six bulky substituents attached at the central heterocyclic framework. Both the starting materials (1c, 1d) and the products (7c, 7d) were characterized by X-ray crystal structure analyses.Keywords: boranes; 1,1-carboboration; Lewis acids; siloles IntroductionThe synthetic chemistry of siloles has found increased interest lately. [1,2] This is mostly due to their use in modern materials chemistry. Suitably substituted silole derivatives have found extensive use due to their photoluminescent properties. [1b,c,3-7] Some derivatives were used as sensor materials. [8] Early synthetic entries to siloles [9] include salt metathesis routes, e.g., by reacting substituted 1,4-dilithiobutadiene reagents with R 2 SiCl 2 substrates. [10,11] A related route was used more recently to prepare lithio-A C H T U N G T R E N N U N G siloles. [12] Other work reported in the last 15 years makes use of the ready formation of the group 4 metallacyclopentadienes [13] and related complexes [14] followed by direct or indirect transmetallation from titanium or zirconium to silicon. [15] Tamao et al. developed an ingenious method of silole formation from bisA C H T U N G T R E N N U N G (alkynyl)silanes (1a) by treatment with Li/naphthalene. [16] The formation of the silole products (3) probably takes place by means of an intramolecular ring closure of a bis-radical anion intermediate (2) (see Scheme 1). This route has extensively been applied for the preparation of novel silole-based electronic materials. [6,7a,b,d-f,h] In this context, boron-and silicon-containing systems have become of interest, and easy accesses to specifically functionalized boryl-substituted siloles or similar compounds are becoming increasingly important.[17] Wrackmeyer et al. have developed and described a fascinating one-pot procedure for the preparation of boryl-substituted silole derivatives (7b) by treatment of a bisA C H T U N G T R E N N U N G (alkynyl)silane (1b) with, for example, triethylborane. [1a,2a,18,19] The unique reaction sequence involves alkynyl abstraction/1,1-carboboration followed by a 1,1-alkenylboration step to directly lead to the boryl-functionalized silole derivative (see Scheme 1).[20] Unfortunately, the reaction with simple alkylboranes often requires elevated temperatures (ca. 100 8C).When more reactive boranes were used (e.g., triallylborane, 1-boraadamantane) the reaction conditions FULL PAPERSof the 1,1-organoboration reactions were milder but sometimes the formation of side products took place. [21] We have now found that this general reaction sequence can very favourably be used for the synthesis of substituted siloles containing a combination of C 6 F 5 and BA C H T U N G T R E N N U N G (C 6 F 5 ) 2 groups that are probably of great advantage in the respective areas of silole-derived materials science. We describe two representative examples in this article. Results and DiscussionFollowing proced...

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Section: Resultsmentioning

confidence: 99%

Reaction of Bis(alkynyl)silanes with Tris(pentafluorophenyl)borane: Synthesis of Bulky Silole Derivatives by Means of 1,1‐Carboboration under Mild Reaction Conditions

et al. 2009

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“…The 13 C NMR spectroscopic signals ( Figure 1) are accompanied by 77 Se satellites, and in the case of 4 b, the 13 C-A C H T U N G T R E N N U N G (CD 2 ) NMR spectroscopic signal is split by H) = 14.2 Hz, in the usual range for such geminal coupling constants. [14] This value can be used in polarization transfer experiments such as insensitive nuclei enhanced by polarization transfer (INEPT) [19] to improve the signal-tonoise ratio of the 77 Se{ 1 H} spectra, with the aim of observing 13 C satellites (middle and lower traces, Figure 2B and C). The case of 4 a is a good example that the higher-field strength B 0 = 11.75 T, as in Figure 2C, does not necessarily help to elucidate important NMR spectroscopic parameters.…”

Section: Resultsmentioning

confidence: 99%

“…1 H} NMR spectrum (refocused INEPT [19] ). C) 95.4 MHz 77 Se{ 1 H} NMR spectrum (refocused INEPT [19] ).…”

Section: Se{mentioning

confidence: 99%

“…C) 95.4 MHz 77 Se{ 1 H} NMR spectrum (refocused INEPT [19] ). The positions of the 13 C satellites in B and C indicate isotope-induced chemical shifts 1 D 12/13 CA C H T U N G T R E N N U N G ( 77 Se), more readily seen, albeit less accurately measured, in the 77 Se NMR spectrum in C. 13 C resonances due to dynamic effects; isotope-induced chemical shifts 1 D are given in ppb, and the negative sign denotes a shift of NMR spectroscopic signal of the heavy isotopomer to lower frequency.…”

Section: Se{mentioning

confidence: 99%

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Synthesis and Reactivity of 4,5‐[1,2‐Dicarba‐closo‐dodecaborano(12)]‐1,3‐diselenacyclopentane: Opening of the Icosahedron to Give a Zwitterionic Intermediate and Conversion into 7,8‐Dicarba‐nido‐undecaborate(1−)

Wrackmeyer

Klimkina

Milius

et al. 2011

Chemistry A European J

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The reaction of the 1,2-diselenolato-1,2-dicarba-closo-dodecaborane(12) dianion [1,2-(1,2-C(2)B(10)H(10))Se(2)](2-) with dichloromethane (CH(2)Cl(2) or CD(2)Cl(2)) in the presence of donor solvents gave 4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3-diselenacyclopentane, the title compound, which was characterized by X-ray structural analysis and NMR spectroscopy ((1)H, (11)B, (13)C, and (77)Se). In the presence of pyridine, opening of the icosahedron took place, and a zwitterionic intermediate was isolated and fully characterized in the solid state by X-ray diffraction and in solution by multinuclear magnetic resonance techniques. Although such types of intermediates, prior to deboronation of the ortho-carborane cage, have been proposed several times, this is first example for which the structure has been confirmed unambiguously. This intermediate possesses a nido structure and contains a 7,8-dicarba-nido-undecaborate(1-) anion and a boronium cation, the latter with two pyridine rings linked to the boron atom, which has been extruded from the cage. It was shown that this process is reversible as long as the deboronation is not complete. The formation of the intermediate is accompanied by deboronation, which leads to the 7,8-dicarba-nido-undecaborate(1-) anion. The latter was prepared independently by conventional routes from the title compound, isolated as crystalline material as the tetrabutyl ammonium salt, and characterized by X-ray structural analysis and multinuclear magnetic resonance spectroscopy ((1)H, (11)B, (13)C, and (77)Se).

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“…2 that the 13 C NMR spectra were recorded with a sufficient signal-to-noise ratio for observing 29 Si satellite signals corresponding to the coupling constants J( 29 Si, 13 C). 23,24 This is extremely helpful for assignment purposes. The assignment of the 13 C NMR signals is further supported by the typically broad NMR signals for boron-bonded 13 C nuclei.…”

Section: Nmr Spectroscopymentioning

confidence: 99%

A novel 4‐methylene‐3‐borahomoadamantane: 1,1‐organoboration of an alkyn‐1‐ylsilane using 1‐boraadamantane

Wrackmeyer

Tok

Milius

2006

Applied Organom Chemis

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1,1-Dibromo-2,2-bis(trimethylsilylethynyl)ethene (2) reacts with two equivalents of 1-boraadamantane (1) by 1,1-organoboration of both trimethylsilylethynyl groups to give a triene 3 bearing two 4-methylene-3-borahomoadamantane moieties in terminal positions. The triene was characterized by one-and two-dimensional 1 H, 11 B, 13 C and 29 Si NMR spectroscopy in solution and X-ray structural analysis in the solid state. The planes of the C C double bond are strongly twisted against each other as a result of the bulky substituents, and the surroundings of the boron atoms deviate from the ideal trigonal planar geometry owing to the tension in the tricyclic frameworks.

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Applications of 29Si NMR Parameters

Cited by 47 publications

References 379 publications

Reaction of Bis(alkynyl)silanes with Tris(pentafluorophenyl)borane: Synthesis of Bulky Silole Derivatives by Means of 1,1‐Carboboration under Mild Reaction Conditions

Reaction of Bis(alkynyl)silanes with Tris(pentafluorophenyl)borane: Synthesis of Bulky Silole Derivatives by Means of 1,1‐Carboboration under Mild Reaction Conditions

Synthesis and Reactivity of 4,5‐[1,2‐Dicarba‐closo‐dodecaborano(12)]‐1,3‐diselenacyclopentane: Opening of the Icosahedron to Give a Zwitterionic Intermediate and Conversion into 7,8‐Dicarba‐nido‐undecaborate(1−)

A novel 4‐methylene‐3‐borahomoadamantane: 1,1‐organoboration of an alkyn‐1‐ylsilane using 1‐boraadamantane

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