Equilibrium between Tetra-, Penta-, and Hexacoordinate Imine and Enamine Chelates of Silicon:  Crystal Structure and Variable-Temperature NMR

Wagler, Jörg; Böhme, Uwe; Brendler, Erica; Roewer, Gerhard

doi:10.1021/om049115s

Cited by 40 publications

(22 citation statements)

References 20 publications

(14 reference statements)

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“…Loss of a greater number of rotational degrees of freedom upon silicon higher coordination would be associated with greater loss in entropy, as shown for an enamine–imine system (loss of rotational degrees of freedom about the Si–O, C–C–C bond and, in part, about a C=N bond, Δ S −116.7 J mol –1 K –1 ). 18 …”

Section: Results and Discussionmentioning

confidence: 99%

Disilanes with Pentacoordinate Si Atoms by Carbon Dioxide Insertion into Aminodisilanes: Syntheses, Molecular Structures, and Dynamic Behavior

et al. 2022

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The insertion of carbon dioxide into the Si–N bonds of aminodisilanes ((RR′N) n Me 3– n Si) 2 affords carbamoyloxydisilanes ((RR′NC(O)O) n Me 3– n Si) 2 . Some of the obtained insertion products feature pentacoordinate silicon atoms in the solid state and in solution, with two carbamoyloxy moieties bridging the Si–Si bond. The aminodisilanes and their insertion products were extensively analyzed, including single-crystal X-ray structure analyses. The temperature dependence of the higher coordination was investigated using variable temperature NMR experiments.

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Section: Results and Discussionmentioning

confidence: 99%

Disilanes with Pentacoordinate Si Atoms by Carbon Dioxide Insertion into Aminodisilanes: Syntheses, Molecular Structures, and Dynamic Behavior

et al. 2022

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“…Trimethylsilyl derivatives of various chelating ligands proved to be suitable starting materials for the syntheses of hypercoordinate silicon complexes [6]. Thus, 1 was silylated to yield 1-(TMS) 2 [6a] and this compound was also reacted with allylphenyldichlorosilane.…”

Section: Resultsmentioning

confidence: 99%

Syntheses of Allyl- and 3-Silylpropyl-substituted Salen-like Tetradentate Ligands via Hypercoordinate Silicon Complexes

Wagler

Roewer

2006

Zeitschrift Für Naturforschung B

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The reaction of allylchlorosilanes (AllSiCl3, AllSiPhCl2) with the tetradentate salen-like ligand 1, o-HO-p-MeO-C6H3-C(Ph)=N-(CH2)2-N=C(Ph)-C6H3-p-OMe-o-OH, yields pentacoordinate silicon complexes of an allyl-substituted ligand system (o-O-p-MeO-C6H3-C(Ph)=N-(CH2)2- N-C(Ph,All)-C6H3-p-OMe-o-O)SiR (2a: R = Ph, 3: R = Cl). The allyl shift step involved in the formation of 2a and 3 probably occurs via an intermediate hexacoordinate silicon complex. This reaction is diastereoselective. The missing diastereomer of 2 (2b) was prepared using an alternative synthesis route, which starts from the trimethylsilyl derivative of ligand 1 o-Me3SiO-p-MeO-C6H3-C(Ph)=N- (CH2)2-N=C(Ph)-C6H3-p-OMe-o-OSiMe3. The diastereomers of 2 obtained from modified reaction pathways give rise to suggestions about the mechanism of formation of these complexes. Further functionalization of the allyl-substituted ligand system of 3 was carried out by hydrosilylation with HSiCl3 to yield complex 4 (o-O-p-MeO-C6H3-C(Ph)=N-(CH2)2-N-C(Ph)[(CH2)3-SiCl3]- C6H3-p-OMe-o-O)SiCl.

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“…The compound has very poor solubility in solvents such as chloroform, THF, benzene, toluene, and acetonitrile. In DMSO it undergoes dissociation and formation of a DMSO‐solvated silicon complex,6s that is [L 1 2 Si(DMSO) 2 ] 2+ , thus it is soluble in [D 6 ]DMSO and produces the same set of NMR signals as L 1 2 Si(OTf) 2 does, which thus forms the same complex in DMSO solution. 1 H NMR (400 MHz, [D 6 ]DMSO): δ =0.98 (t, 3 J (H,H)=7.7 Hz, 6 H, CH 2 C H 3 ), 2.18 (s, 6 H, CH 3 ), 2.22 (s, 6 H, CH 3 ), 2.39 (q, 3 J (H,H)=7.7 Hz, 4 H, C H 2 CH 3 ), 7.22 (d, 7.1 Hz, 2 H, Si(oPh)), 7.39 (m, 2 H, Si(mPh)), 7.49 (m, 1 H, Si(pPh)), 7.73 (m, 4 H, mPh L ), 7.83 (m, 2 H, pPh L ), 8.07 ppm (d, 7.4 Hz, 4 H, oPh L ); 13 C NMR (100.1 MHz, [D 6 ]DMSO): δ =12.4, 13.3, 13.9, 16.9 (alkyl), 34 (broad multiplet, Si‐coordinated [D 6 ]DMSO), 129.1, 129.9, 130.1, 133.8, 133.9, 137.5, 139.0, 158.9, 168.5 ppm (CO); 29 Si NMR (79,5 MHz, [D 6 ]DMSO): δ =−175.5 ppm.…”

Section: Methodsmentioning

confidence: 99%

“…In the course of our investigations, we have studied silicon complexes with bi‐, tri‐, and tetradentate O , N ‐donor ligands,3b,c,f, 4a,b, 6 silicon complexes with five‐membered N ‐heterocyclic donor moieties,2g, h, 7 and other silicon compounds of pyrrole‐derived ligand systems 8. In the work reported herein, we now address silicon complexes with pyrrole‐functionalized bidentate O , N ‐chelating ligands.…”

Section: Introductionmentioning

confidence: 99%

2‐Acylpyrroles as Mono‐anionic O,N‐Chelating Ligands in Silicon Coordination Chemistry

Kämpfe

Brendler

Kroke

et al. 2014

Chemistry A European J

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Kryptopyrrole (2,4-dimethyl-3-ethylpyrrole) was acylated with, for example, benzoyl chloride to afford 2-benzoyl-3,5-dimethyl-4-ethylpyrrole (L(1)H). With SiCl4 this ligand reacts under liberation of HCl and formation of the complex L(1)2SiCl2. In related reactions with HSiCl3 or H2SiCl2, the same chlorosilicon complex is formed under liberation of HCl and H2 or liberation of H2, respectively. The chlorine atoms of L(1)2SiCl2 can be replaced by fluoride and triflate using ZnF2 and Me3Si-OTf, respectively. The use of a supporting base (triethylamine) is required for the complexation of phenyltrichlorosilane and diphenyldichlorosilane. The complexes L(1)2SiCl2, L(1)2SiF2, L(1)2Si(OTf)2, L(1)2SiPhCl, and L(1)2SiPh2 exhibit various configurations of the octahedral silicon coordination spheres (i.e. cis or trans configuration of the monodentate substituents, different orientations of the bidentate chelating ligands relative to each other). Furthermore, cationic silicon complexes L(1)3Si(+) and L(1) SiPh(+) were synthesized by chloride abstraction with GaCl3. In contrast, reaction of L(1)2SiCl2 with a third equivalent of L(1)H in the presence of excess triethylamine produced a charge-neutral hexacoordinate Si complex with a new tetradentate chelating ligand which formed by Si-templated C-C coupling of two ligands L(1).

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Equilibrium between Tetra-, Penta-, and Hexacoordinate Imine and Enamine Chelates of Silicon: Crystal Structure and Variable-Temperature NMR

Cited by 40 publications

References 20 publications

Disilanes with Pentacoordinate Si Atoms by Carbon Dioxide Insertion into Aminodisilanes: Syntheses, Molecular Structures, and Dynamic Behavior

Disilanes with Pentacoordinate Si Atoms by Carbon Dioxide Insertion into Aminodisilanes: Syntheses, Molecular Structures, and Dynamic Behavior

Syntheses of Allyl- and 3-Silylpropyl-substituted Salen-like Tetradentate Ligands via Hypercoordinate Silicon Complexes

2‐Acylpyrroles as Mono‐anionic O,N‐Chelating Ligands in Silicon Coordination Chemistry

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