Tin-119 chemical shifts of ortho, meta, para, 2,6-, and polysubstituted aryltrimethyltin derivatives and related organotin compounds

Kroth, Heiko; Schumann, Herbert; Kuivila, Henry G.; Schaeffer, Charles D.; Zuckerman, J. J.

doi:10.1021/ja00840a023

Cited by 53 publications

(10 citation statements)

References 5 publications

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“…The 73 Ge spectra obtained here display an overall chemical shift range approaching 4.6 ppm, exceeding the 1.35 ppm range observed for the quaternary carbon 13 C shifts in t-butylbenzenes 12 and for 29 Si shifts (2.43 ppm) reported in aryltrimethylsilanes, 19 but somewhat less than the 119 Sn chemical shift range (4.9 ppm) recorded for aryltrimethylstannanes, 13 all systems similarly substituted. Table 3 provides parameters from least-squares regression analyses of 1 H, 13 C, and 73 Ge NMR shifts against normal Hammett sigma substituent constants. 20,21 A value of 0.140 was used for p-Sn CH 3 3 .…”

Section: Spectral Assignments and Reference Datacontrasting

confidence: 65%

“…Use of regression analysis data in Table 4 and 13 C shifts of p-bis(tbutyl)benzene of C-1, CH 3 , and C-˛lead to an average sigma constant of 0.12, in remarkably good agreement with the standard reactivitybased value of 0.197 20,21 for p-C CH 3 3 . Similar procedure using 13 C shifts for C-1 and CH 3 of bis(trimethylsilyl)benzene leads to an average value of C0.14, which also compares favorably with the reactivity-based value of 0.070 20,21 for p-Si CH 3 3 .…”

Section: Spectral Assignments and Reference Datamentioning

confidence: 55%

“…1 H and 73 Ge chemical shifts, and 73 Ge resonance linewidths at half-height are listed in Table 2. Assignments of 13 C resonances were based on (i) additivity relationships; (ii) off-resonance protoncoupled spectra; (iii) comparison of 13 C chemical shifts with those reported in our previous studies of substituted t-butylbenzenes, 12 aryltrimethylsilanes, 12 -germanes, 12 and -stannanes; 9,10,12 and for four derivatives, and (iv) established trends in magnitude of J 19 F-13 C and J 119 Sn-13 C coupling constants in these systems. 9,10 The 73 Ge spectra in this work display relatively sharp resonances with half-height peak widths ( …”

Section: Resultsmentioning

confidence: 99%

“…2 This present study of aryltrimethylgermane derivatives was designed to complete our previous studies of the transmission of substituent effects in group 14 aromatic systems. 3 -14 We have obtained 1 H, 13 C, and 73 Ge NMR chemical shifts in substituted aryltrimethylgermanes, produced correlations of these shifts with Hammett sigma constants, and derived a sigma constant for the p-Ge CH 3 3 group.…”

Section: Introductionmentioning

confidence: 99%

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1H,13C, and73Ge NMR spectral analysis of substituted aryltrimethylgermanes

Fleisher¹,

Schaeffer²,

Buckwalter³

et al. 2006

Magn. Reson. Chem.

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NMR chemical shifts of 1H, 13C, and 73Ge are reported for a series of monosubstituted aromatic trimethylgermanes of the type XC6H4Ge(CH3)3; X = p-N(CH3)2, p-OCH3, p-OC2H5, p-C(CH3)3, p-Si(CH3)3, p-Ge(CH3)3, p-Sn(CH3)3, p-CH3, m-CH3, -H, m-OCH3, p-Cl, p-Br, m-F, m-CF3, p-CF3, o-OCH3, and o-CH3. The relatively narrow 73Ge resonances show a strong correlation with Hammett sigma constants, with a correlation coefficient of 0.976 and 0.876 for 73Ge chemical shifts in meta- and para-substituted derivatives, respectively. The 13C chemical shifts of the methyl carbons bonded to germanium also display a relationship, with correlation coefficients of 0.904, 0.993, and 0.911 for para-, meta- and all derivatives, respectively. Comparisons of the Hammett plots for the homologous series XC6H4M(CH3)3; M = C, Si, Ge, Sn, show that, in general, correlation coefficients decrease while slopes increase significantly down the group, presumably reflecting the corresponding increase in chemical shift range of the group 14 atom. The Hammett constant derived for the p-Ge(CH3)3 group of +0.13 compares with the NMR-derived constants of -0.12 for p-C(CH3)3, +0.14 for p-Si(CH3)3, and -0.14 for p-Sn(CH3)3. The indication of electron release by carbon and tin can be rationalized through traditional hyperconjugative arguments for carbon and by the low electronegativity and consequent inductive effect of tin. The small electron attraction suggested by the positive constants for silicon and germanium can be simply, and perhaps naively, attributed to pi-acceptor interactions with the benzene ring.

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Section: Spectral Assignments and Reference Datacontrasting

confidence: 65%

Section: Spectral Assignments and Reference Datamentioning

confidence: 55%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

1H,13C, and73Ge NMR spectral analysis of substituted aryltrimethylgermanes

Fleisher¹,

Schaeffer²,

Buckwalter³

et al. 2006

Magn. Reson. Chem.

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show abstract

“…The 119 Sn{ 1 H} NMR resonance for 3 (d À37.9) is similar to those for related organostannanes 2,6-(MeO) 2 C 6 H 3 SnMe 3 (d À43.7) and 2,4,6-(MeO) 3 C 6 H 2 SnMe 3 (d À43.8) [17]. The 29 Si{ 1 H} chemical shift for 2 is very similar to that for the corresponding unsubstituted phenyl derivative PhSiMe 3 (d 29Si ¼ À4.1 in CDCl 3 ) [18]; and indicates that there is likely no coordination of the phenoxy units to the silicon atom in solution.…”

Section: Synthesessupporting

confidence: 56%

Synthesis and characterisation of complexes of the 2,6-diphenoxyphenyl ligand

Blake

Gower

Lewis

et al. 2011

Journal of Organometallic Chemistry

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Heteroatom‐Facilitated Lithiations

Gschwend¹,

Rodriguez²

1979

Organic Reactions

185

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Some 25 years have elapsed since the topic of metalation reactions was reviewed by Gilman and Morton. The intervening years have been notable for intensive explorations in this area, in part because many organolithium reagents are now commercially available. Specifically, research efforts have been characterized by the discovery of new functional groups that promote metalation, elaboration of novel heterocyclic and olefinic substrates as metalatable species, recognition of new types of lithiating agents, and the continuation of efforts to define accurately the mechanism of metalation. Accordingly, heteroatom‐facilitated lithiation has become recognized as an increasingly important tool, not only in the elaboration of carbocyclic aromatic and heteroaromatic systems, but also in synthetic aliphatic chemistry. A few recent reviews have covered the topic in a more limited or less specific sense. It is the purpose of this chapter to survey and classify the vast accumulation of heteroatom‐facilitated lithiations recorded since the first coverage in Organic Reactions . As outlined by Gilman and Morton, the terms “metalation” in general and “lithiation” in particular denote any replacement of a hydrogen atom by metal or lithium. In this review, however, lithiation is defined as the exchange of a hydrogen atom attached to an sp 2 ‐hybridized carbon atom by lithium to form a covalent lithium‐carbon bond. More specifically, discussion is limited to those metalations that, through the influence of a heteroatom, are characterized by rate enhancement and regioselectivity. In fact, lithiation reactions of this type are noted for an extraordinarily high degree of regioselectivity, metalation generally occurring on the sp 2 ‐carbon atom closest to the heteroatom. Based on the relative position of the heteroatom, such lithiations are conveniently classified into two principal categories: alpha and beta ( ortho ) lithiations. In alpha lithiations the metalating agent deprotonates the sp 2 ‐carbon atom alpha to the heteroatom to form a carbonlithium bond. This sp 2 ‐carbon atom may be part of an olefinic or heteroaromatic π system. In beta lithiations the metalating agent is directed to deprotonate the sp 2 ‐carbon atom beta to the heteroatom‐containing substituent. The sp 2 ‐carbon atom can be part of an aromatic or an olefinic π system. It should be noted that the designation “ ortho metalation” is used specifically for the beta metalation of carbocyclic aromatic systems. This chapter surveys all systems in which alpha and beta lithiations have been observed, with the exception of ferrocenes.

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Tin-119 chemical shifts of ortho, meta, para, 2,6-, and polysubstituted aryltrimethyltin derivatives and related organotin compounds

Cited by 53 publications

References 5 publications

1H,13C, and73Ge NMR spectral analysis of substituted aryltrimethylgermanes

1H,13C, and73Ge NMR spectral analysis of substituted aryltrimethylgermanes

Synthesis and characterisation of complexes of the 2,6-diphenoxyphenyl ligand

Heteroatom‐Facilitated Lithiations

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