Synthesis of 4‑Silacyclohexan-1-ones and (4-Silacyclohexan-1-yl)amines Containing the Silicon Protecting Groups MOP (4-Methoxyphenyl), DMOP (2,4-Dimethoxyphenyl), or TMOP (2,4,6-Trimethoxyphenyl): Versatile Si- and C‑Functional Building Blocks for Synthesis

The 4-silacyclohexanones <b>1</b>–<b>6</b> were prepared in convenient multistep syntheses, starting from MeSi­(OMe)₃ and PhSi­(OMe)₃, respectively. Cleavage of the 4-methoxyphenyl (MOP), 2,6-dimethoxyphenyl (DMOP), and 2,4,6-trimethoxyphenyl (TMOP) protecting groups of <b>4</b>–<b>6</b> by treatment with HCl/Et₂O in CH₂Cl₂ at 20 °C gives the 4-chloro-4-silacyclohexanone <b>13</b>. Reductive amination of <b>1</b>–<b>6</b> with NH₃ or <i>i</i>-PrNH₂ yields the respective (4-silacyclohexan-1-yl)­amines <b>7</b>–<b>12</b>. Compounds <b>1</b>–<b>12</b> and all new precursors synthesized were characterized by elemental analyses (C, H, N) or mass spectrometric investigations (ESI-HRMS) and by NMR spectroscopic studies (¹H, ¹³C, ²⁹Si). Compounds <b>1</b>, <b>3</b>, <b>5</b>, and <b>6</b> and the precursors (MeO)₂SiPh­(TMOP) (<b>21</b>) and (CH₂CH)₂SiPh­(TMOP) (<b>27</b>) were additionally characterized by single-crystal X-ray diffraction. Compounds <b>1</b>–<b>12</b> with their Si- and C-functional groups represent versatile building blocks for synthesis

Diindole-Annulated Naphthalene Diimides: Synthesis and Optical and Electronic Properties of <i>Syn</i>- and <i>Anti</i>-Isomers

Here we report a selective method for the core-extension of naphthalene diimide (NDI) with two annulated indole rings leading to carbazolo­[2,3-<i>b</i>]­carbazole diimides (CbDIs) with exclusive <i>syn</i>-connectivity based on a regioselective nucleophilic substitution reaction of Br₄-NDI with arylamines, followed by palladium-catalyzed intramolecular C–C coupling. The oxygen analogues of <i>anti</i>-CbDIs, namely <i>anti</i>-benzofurobenzofuran diimides (<i>anti</i>-BfDIs), were obtained from 2,6-Br₂-NDI and 2-bromophenol. The <i>syn</i>- and <i>anti</i>-isomers of CbDIs were unambiguously characterized by single-crystal X-ray analysis. The optical properties of the present core-enlarged NDIs were studied, revealing clear differences in the absorption characteristics of the <i>syn</i>- and <i>anti</i>-isomers of CbDI, on one hand, and CbDI vs BfDI derivatives, on the other hand. Cyclic voltammetry studies showed that the redox properties are dependent on the substituents at the CbDI-core and oxygen atom containing BfDIs are more prone to reduction than the respective nitrogen analogues CbDIs. Vacuum-processed organic field effect transistors reveal CbDI and BfDI derivatives with n-channel, p-channel, as well as ambient transport characteristics with mobility values up to 0.2 cm²/(V s)

Diindole-Annulated Naphthalene Diimides: Synthesis and Optical and Electronic Properties of <i>Syn</i>- and <i>Anti</i>-Isomers

Here we report a selective method for the core-extension of naphthalene diimide (NDI) with two annulated indole rings leading to carbazolo­[2,3-<i>b</i>]­carbazole diimides (CbDIs) with exclusive <i>syn</i>-connectivity based on a regioselective nucleophilic substitution reaction of Br₄-NDI with arylamines, followed by palladium-catalyzed intramolecular C–C coupling. The oxygen analogues of <i>anti</i>-CbDIs, namely <i>anti</i>-benzofurobenzofuran diimides (<i>anti</i>-BfDIs), were obtained from 2,6-Br₂-NDI and 2-bromophenol. The <i>syn</i>- and <i>anti</i>-isomers of CbDIs were unambiguously characterized by single-crystal X-ray analysis. The optical properties of the present core-enlarged NDIs were studied, revealing clear differences in the absorption characteristics of the <i>syn</i>- and <i>anti</i>-isomers of CbDI, on one hand, and CbDI vs BfDI derivatives, on the other hand. Cyclic voltammetry studies showed that the redox properties are dependent on the substituents at the CbDI-core and oxygen atom containing BfDIs are more prone to reduction than the respective nitrogen analogues CbDIs. Vacuum-processed organic field effect transistors reveal CbDI and BfDI derivatives with n-channel, p-channel, as well as ambient transport characteristics with mobility values up to 0.2 cm²/(V s)

Diindole-Annulated Naphthalene Diimides: Synthesis and Optical and Electronic Properties of <i>Syn</i>- and <i>Anti</i>-Isomers

Here we report a selective method for the core-extension of naphthalene diimide (NDI) with two annulated indole rings leading to carbazolo­[2,3-<i>b</i>]­carbazole diimides (CbDIs) with exclusive <i>syn</i>-connectivity based on a regioselective nucleophilic substitution reaction of Br₄-NDI with arylamines, followed by palladium-catalyzed intramolecular C–C coupling. The oxygen analogues of <i>anti</i>-CbDIs, namely <i>anti</i>-benzofurobenzofuran diimides (<i>anti</i>-BfDIs), were obtained from 2,6-Br₂-NDI and 2-bromophenol. The <i>syn</i>- and <i>anti</i>-isomers of CbDIs were unambiguously characterized by single-crystal X-ray analysis. The optical properties of the present core-enlarged NDIs were studied, revealing clear differences in the absorption characteristics of the <i>syn</i>- and <i>anti</i>-isomers of CbDI, on one hand, and CbDI vs BfDI derivatives, on the other hand. Cyclic voltammetry studies showed that the redox properties are dependent on the substituents at the CbDI-core and oxygen atom containing BfDIs are more prone to reduction than the respective nitrogen analogues CbDIs. Vacuum-processed organic field effect transistors reveal CbDI and BfDI derivatives with n-channel, p-channel, as well as ambient transport characteristics with mobility values up to 0.2 cm²/(V s)

Lewis Acid/Base Reactions of the Bis(amidinato)silylene [<i>i</i>PrNC(Ph)N<i>i</i>Pr]₂Si and Bis(guanidinato)silylene [<i>i</i>PrNC(N<i>i</i>Pr₂)N<i>i</i>Pr]₂Si with ElPh₃ (El = B, Al)

The bis­(amidinato)­silylene [<i>i</i>PrNC­(Ph)­N<i>i</i>Pr]₂Si and the analogous bis­(guanidinato)­silylene [<i>i</i>PrNC­(N<i>i</i>Pr₂)­N<i>i</i>Pr]₂Si react with the Lewis acids BPh₃ and AlPh₃ to form the respective Lewis acid/base adducts <b>4</b>–<b>7</b> (adduct <b>4</b> has already been described). Compounds <b>5</b> and <b>7</b> are the first silylene–alane adducts and the first five-coordinate silicon­(II) compounds with an Si–Al bond, and <b>6</b> and <b>7</b> represent the first silylene–borane and silylene–alane adducts, respectively, that are derived from a bis­(guanidinato)­silylene. Compounds <b>4</b>–<b>7</b> were characterized by single-crystal X-ray diffraction and solid-state NMR spectroscopy (¹¹B, ¹⁵N, ²⁷Al, ²⁹Si), and <b>4</b> and <b>5</b> were additionally studied by NMR spectroscopy in solution (¹H, ¹¹B, ¹³C, ²⁷Al, ²⁹Si)

Bis[<i>N</i>,<i>N</i>′‑diisopropylbenzamidinato(−)]silicon(II): Cycloaddition Reactions with Organic 1,3-Dienes and 1,2-Diketones

Reaction of the donor-stabilized silylene <b>1</b> (which is three-coordinate in the solid state and four-coordinate in solution) with organic 1,3-dienes (2,3-dimethyl-1,3-butadiene, 1,3-butadiene, (<i>E</i>,<i>E</i>)-1,4-diphenyl-1,3-butadiene, 2,3-dibenzyl-1,3-butadiene, 1,3-cyclohexadiene, or cyclo­octatetraene) and 1,2-diketones (3,5-di-<i>tert</i>-butyl-1,2-benzoquinone or 1,2-diphenyl­ethane-1,2-dione) leads to the formation of the respective cycloaddition products <b>2</b>–<b>9</b>. Compounds <b>2</b>–<b>9</b> were characterized by crystal structure analyses (<b>7</b> was studied as the hemi solvate <b>7</b>·​0.5<i>n</i>-C₆H₁₄) and NMR spectroscopic studies in the solid state and in solution. As the amidinato ligands can switch between a monodentate and bidentate coordination mode, for some of the cycloaddition products studied, the silicon coordination number in the solid state and in solution is different. For example, compound <b>4</b> is four- (<b>4a</b>) and six-coordinate (<b>4b</b>) in the solid state (isolated as a 1:1 cocrystallizate of <b>4a</b> and <b>4b</b>) and five-coordinate in solution. As demonstrated for the methanolysis of <b>2</b> (formation of <b>10</b>; proof of principle), compounds <b>2</b>–<b>7</b> with their reactive Si–N bonds are starting materials for the synthesis of promising mono- and bicyclic organosilicon compounds

Synthesis of Silicon-Functionalized (Silylmethyl)silanes and α,ω-Dichlorocarbosilanes Using the TMOP (2,4,6-Trimethoxyphenyl) Protecting Group: (TMOP)Me₂SiCH₂Cl and (TMOP)₂MeSiCH₂Cl as Reagents To Introduce the ClMe₂SiCH₂, MeOMe₂SiCH₂, or Cl₂MeSiCH₂ Group by Nucleophilic Substitution at Silicon

In this study, the synthetic potential of the 2,4,6-trimethoxyphenyl (TMOP)-substituted (chloromethyl)­silanes (TMOP)­Me₂SiCH₂Cl (<b>1</b>) and (TMOP)₂MeSiCH₂Cl (<b>2</b>) for the preparation of Si-functionalized (silylmethyl)­silanes and α,ω-dichlorocarbosilanes (with skeletons consisting of alternate carbon and silicon atoms) was investigated. Compounds <b>1</b> and <b>2</b> were used as reagents to introduce the ClMe₂SiCH₂, MeOMe₂SiCH₂, or Cl₂MeSiCH₂ group by nucleophilic substitution at silicon. The three-step synthetic method involves the (i) transformation of <b>1</b> and <b>2</b> into (TMOP)­Me₂SiCH₂MgCl, (TMOP)­Me₂SiCH₂Li, (TMOP)₂MeSiCH₂MgCl, and (TMOP)₂MeSiCH₂Li, respectively, (ii) reaction of these nucleophiles with chloro- or methoxysilanes, and (iii) subsequent selective cleavage of the TMOP protecting group with HCl/Et₂O or MeOH/[CF₃COOH]. Using this method, the following compounds were prepared: ClMe₂SiCH₂SiMe₃ (<b>3</b>), ClMe₂SiCH₂SiMe₂Cl (<b>4</b>), ClMe₂SiCH₂SiMeCl₂ (<b>5</b>), ClMe₂SiCH₂SiCl₃ (<b>6</b>), ClMe₂SiCH₂Si­(OMe)₃ (<b>7</b>), MeOMe₂SiCH₂Si­(OMe)₃ (<b>8</b>), Cl₂MeSiCH₂SiMe₃ (<b>9</b>), Me₂Si­(CH₂SiMe₂Cl)₂ (<b>10</b>), and Me₂Si­(CH₂SiMe₂CH₂SiMe₂Cl)₂ (<b>11</b>)

Five-Coordinate Silicon(II) Compounds with Si–M Bonds (M = Cr, Mo, W, Fe): Bis[<i>N</i>,<i>N</i>′‑diisopropylbenzamidinato(−)]silicon(II) as a Ligand in Transition-Metal Complexes

Reaction of the donor-stabilized silylene <b>1</b> with [Cr­(CO)₆], [Mo­(CO)₆], [W­(CO)₆], or [Fe­(CO)₅] leads to the formation of the transition-metal silylene complexes <b>2</b>–<b>5</b>, which contain five-coordinate silicon­(II) moieties with Si–M bonds (M = Cr, Mo, W, Fe). These compounds were characterized by NMR spectroscopic studies in the solid state and in solution and by crystal structure analyses. These experimental investigations were complemented by computational studies to gain insight into the bonding situation of <b>2</b>–<b>5</b>. The nature of the Si–M bonds is best described as a single bond

Neutral Six-Coordinate and Cationic Five-Coordinate Silicon(IV) Complexes with Two Bidentate Monoanionic <i>N</i>,<i>S</i>‑Pyridine-2-thiolato(−) Ligands

A series of neutral six-coordinate silicon­(IV) complexes (<b>4</b>–<b>11</b>) with two bidentate monoanionic <i>N</i>,<i>S</i>-pyridine-2-thiolato ligands and two monodentate ligands R¹ and R² was synthesized (<b>4</b>, R¹ = R² = Cl; <b>5</b>, R¹ = Ph, R² = Cl; <b>6</b>, R¹ = Ph, R² = F; <b>7</b>, R¹ = Ph, R² = Br; <b>8</b>, R¹ = Ph, R² = N₃; <b>9</b>, R¹ = Ph, R² = NCO; <b>10</b>, R¹ = Ph, R² = NCS; <b>11</b>, R¹ = Me, R² = Cl). In addition, the related ionic compound <b>12</b> was synthesized, which contains a cationic five-coordinate silicon­(IV) complex with two bidentate monoanionic <i>N</i>,<i>S</i>-pyridine-2-thiolato ligands and one phenyl group (counterion: I^–). Compounds <b>4</b>–<b>12</b> were characterized by elemental analyses, NMR spectroscopic studies in the solid state and in solution, and crystal structure analyses (except <b>7</b>). These structural investigations were performed with a special emphasis on the sophisticated stereochemistry of these compounds. These experimental investigations were complemented by computational studies, including bonding analyses based on relativistic density functional theory

Neutral Six-Coordinate and Cationic Five-Coordinate Silicon(IV) Complexes with Two Bidentate Monoanionic <i>N</i>,<i>S</i>‑Pyridine-2-thiolato(−) Ligands

A series of neutral six-coordinate silicon­(IV) complexes (<b>4</b>–<b>11</b>) with two bidentate monoanionic <i>N</i>,<i>S</i>-pyridine-2-thiolato ligands and two monodentate ligands R¹ and R² was synthesized (<b>4</b>, R¹ = R² = Cl; <b>5</b>, R¹ = Ph, R² = Cl; <b>6</b>, R¹ = Ph, R² = F; <b>7</b>, R¹ = Ph, R² = Br; <b>8</b>, R¹ = Ph, R² = N₃; <b>9</b>, R¹ = Ph, R² = NCO; <b>10</b>, R¹ = Ph, R² = NCS; <b>11</b>, R¹ = Me, R² = Cl). In addition, the related ionic compound <b>12</b> was synthesized, which contains a cationic five-coordinate silicon­(IV) complex with two bidentate monoanionic <i>N</i>,<i>S</i>-pyridine-2-thiolato ligands and one phenyl group (counterion: I^–). Compounds <b>4</b>–<b>12</b> were characterized by elemental analyses, NMR spectroscopic studies in the solid state and in solution, and crystal structure analyses (except <b>7</b>). These structural investigations were performed with a special emphasis on the sophisticated stereochemistry of these compounds. These experimental investigations were complemented by computational studies, including bonding analyses based on relativistic density functional theory