Silenes: Connectors between classical alkenes and nonclassical heavy alkenes

Ottosson, Henrik; Eklöf, Anders M.

doi:10.1016/j.ccr.2007.07.005

Cited by 137 publications

(100 citation statements)

References 181 publications

(236 reference statements)

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“…Das Signal bei d = À4.4 ppm gehçrt zum Si = C-Siliciumatom, das bei deutlich hçherem Feld erscheint als die meisten bisher bekannten Silene, was auf eine invers polarisierte Si=C-Bindung schließen lässt. [17] Das 13 C-NMR-Signal der Si=C-Einheit wird allerdings ebenfalls bei relativ hohem Feld beobachtet (d = 144.15 ppm), wahrscheinlich infolge der Inkorporation in den dreigliedrigen Ring. Signifikant hochfeldverschobene Signale für beide Atome der Si = C-Einheit wurden ebenfalls im Fall eines stabilen 4-Silatriafulvens beobachtet.…”

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Reversible, vollständige Spaltung von SiSi‐Bindungen durch Isocyanidinsertion

et al. 2013

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Reversible, vollständige Spaltung von SiSi‐Bindungen durch Isocyanidinsertion

et al. 2013

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“…[32] The ZPVE-corrected calculated bond dissociation energy D 0 (0) of the silicon compound 3 b (94.3 kJ mol…”

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confidence: 99%

Stable N‐Heterocyclic Carbene Adducts of Arylchlorosilylenes and Their Germanium Homologues

Filippou

Chernov

Blom

et al. 2010

Chemistry A European J

146

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The first N-heterocyclic carbene adducts of arylchlorosilylenes are reported and compared with the homologous germanium compounds. The arylsilicon(II) chlorides SiArCl(Im-Me(4)) [Ar=C(6)H(3)-2,6-Mes(2) (Mes=C(6)H(2)-2,4,6-Me(3)), C(6)H(3)-2,6-Trip(2) (Trip=C(6)H(2)-2,4,6-iPr(3))] were obtained selectively on dehydrochlorination of the arylchlorosilanes SiArHCl(2) with 1,3,4,5-tetramethylimidazol-2-ylidene (Im-Me(4)). The analogous arylgermanium(II) chlorides GeArCl(Im-Me(4)) were prepared by metathetical exchange of GeCl(2)(Im-Me(4)) with LiC(6)H(3)-2,6-Mes(2) or addition of Im-Me(4) to GeCl(C(6)H(3)-2,6-Trip(2)). All compounds were fully characterized. Density functional calculations on ECl(C(6)H(3)-2,6-Trip(2))(Im-Me(4)), where E=Si, Ge, at different levels of theory show very good agreement between calculated and experimental bonding parameters, and NBO analyses reveal similar electronic structures of the two aryltetrel(II) chlorides. The low gas-phase Gibbs free energy of bond dissociation of SiCl(C(6)H(3)-2,6-Trip(2))(Im-Me(4)) (Delta(calcd) degrees=28.1 kJ mol(-1)) suggests that the carbene adducts SiArCl(Im-Me(4)) may be valuable transfer reagents of the arylsilicon(II) chlorides SiArCl.

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“…From this, one can infer that the T 1 state PES of also other photoreactions will vary in dependence of a neighboring [4n + 2]-or [4n]annulene ring. BenzoSCB (2a, Figure 2) should photorearrange to o-silaxylylene (2b), containing a highly reactive Si=C double bond [43], while cyclobuteno-(1a) and cyclooctatetraenoSCB (3a), based on our hypothesis, should be resistant to photochemical ring-openings. Indeed, photochemical ring-opening of 2a in the S 1 state to the transient 2b, trapped by alcohol solvents to yield isolable silylethers in 40-80% yield (Scheme 1), was earlier reported by Kang and co-workers [44].…”

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confidence: 76%

The Silacyclobutene Ring: An Indicator of Triplet State Baird-Aromaticity

2017

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Baird's rule tells that the electron counts for aromaticity and antiaromaticity in the first ππ* triplet and singlet excited states (T 1 and S 1 ) are opposite to those in the ground state (S 0 ). Our hypothesis is that a silacyclobutene (SCB) ring fused with a [4n]annulene will remain closed in the T 1 state so as to retain T 1 aromaticity of the annulene while it will ring-open when fused to a [4n + 2]annulene in order to alleviate T 1 antiaromaticity. This feature should allow the SCB ring to function as an indicator for triplet state aromaticity. Quantum chemical calculations of energy and (anti)aromaticity changes along the reaction paths in the T 1 state support our hypothesis. The SCB ring should indicate T 1 aromaticity of [4n]annulenes by being photoinert except when fused to cyclobutadiene, where it ring-opens due to ring-strain relief.

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Silenes: Connectors between classical alkenes and nonclassical heavy alkenes

Cited by 137 publications

References 181 publications

Reversible, vollständige Spaltung von SiSi‐Bindungen durch Isocyanidinsertion

Reversible, vollständige Spaltung von SiSi‐Bindungen durch Isocyanidinsertion

Stable N‐Heterocyclic Carbene Adducts of Arylchlorosilylenes and Their Germanium Homologues

The Silacyclobutene Ring: An Indicator of Triplet State Baird-Aromaticity

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