Modern concepts and methods in the chemistry of polyhedral metallasiloxanes

Levitsky, Mikhail M.; Bilyachenko, Аlexey N.

doi:10.1016/j.ccr.2015.07.007

Cited by 82 publications

(66 citation statements)

References 163 publications

(199 reference statements)

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“…In turn, the location of sodium ions in 1 is far from being classical. For Regarding the rest of the structure of 1, it is also notable that the principle of cyclic silsesquioxane ligands' coordination to copper ions (in a sandwich manner as seen in Figure 4, left) is well-described in CLMSs chemistry [1,6,10]. In turn, the location of sodium ions in 1 is far from being classical.…”

Section: Figurementioning

confidence: 99%

“…Cage metallasilsesquioxanes (CLMSs) [1][2][3][4][5][6][7][8][9][10] are popular objects for the investigation of regularities in the insertion of metal ions into the siloxane matrix [11][12][13][14][15][16][17][18], the study of catalytic [19][20][21][22][23][24] properties, magnetic (spin) glass [25], as well as the study of nanoparticles [26] and macrocyclic siloxane material [27] formation.…”

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confidence: 99%

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Palanquin-Like Cu4Na4 Silsesquioxane Synthesis (via Oxidation of 1,1-bis(Diphenylphosphino)methane), Structure and Catalytic Activity in Alkane or Alcohol Oxidation with Peroxides

et al. 2019

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The self-assembly synthesis of copper-sodium phenylsilsesquioxane in the presence of 1,1-bis(diphenylphosphino)methane (dppm) results in an unprecedented cage-like product: [(PhSiO 1,5 ) 6 ] 2 [CuO] 4 [NaO 0.5 ] 4 [dppmO 2 ] 2 1. The most intriguing feature of the complex 1 is the presence of two oxidized dppm species that act as additional O-ligands for sodium ions. Two cyclic phenylsiloxanolate (PhSiO 1,5 ) 6 ligands coordinate in a sandwich manner with the copper(II)-containing layer of the cage. The structure of 1 was established by X-ray diffraction analysis. Complex 1 was shown to be a very good catalyst in the oxidation of alkanes and alcohols with hydrogen peroxide or tert-butyl hydroperoxide in acetonitrile solution. Thus, cyclohexane (CyH), was transformed into cyclohexyl hydroperoxide (CyOOH), which could be easily reduced by PPh 3 to afford stable cyclohexanol with a yield of 26% (turnover number (TON) = 240) based on the starting cyclohexane. 1-Phenylethanol was oxidized by tert-butyl hydroperoxide to give acetophenone in an almost quantitative yield. The selectivity parameters of the oxidation of normal and branched alkanes led to the conclusion that the peroxides H 2 O 2 and tert-BuOOH, under the action of compound (1), decompose to generate the radicals HO • and tert-BuO • which attack the C-H bonds of the substrate.

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Section: Figurementioning

confidence: 99%

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confidence: 99%

Palanquin-Like Cu4Na4 Silsesquioxane Synthesis (via Oxidation of 1,1-bis(Diphenylphosphino)methane), Structure and Catalytic Activity in Alkane or Alcohol Oxidation with Peroxides

et al. 2019

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“…Drawing an analogy between Fe‐based sesquioxanes of germanium and silicon, we would like to emphasize that known types of cage ironsilsesquioxanes (Refs. ,,) have quite different structural features in comparison to germanium‐based compounds 1 – 4 . This suggests a unique role of germanium centers in cage‐compound formation.…”

Section: Figurementioning

confidence: 99%

Cage‐like Fe,Na‐Germsesquioxanes: Structure, Magnetism, and Catalytic Activity

et al. 2016

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As eries of four unprecedented heterometallic metallagermsesquioxanes were synthesized. Their cage-like architectures have au nique type of molecular topology consisting of the hexairon oxo{ Fe 6 O 19 }c ore surrounded in at riangular manner by three cyclic germoxanolates [PhGe-(O)O] 5 .T his structural organization induces antiferromagnetic interactions between the Fe III ions through the oxygen atoms.E valuated for this first time in catalysis,t hese compounds showed ah igh catalytic activity in the oxidation of alkanes and the oxidative formation of benzamides from alcohols.The design of metal-based polycyclicc age-like compounds has attracted ag reat deal of attention from researchers worldwide over several decades owing to their structural diversity and their potential technological applications especially in catalysis. [1] Numerous metal-oxygen clusters, [1b,c,j] metal-organic frameworks [1d,l,m] or metal-organic polyhedrons [1f,n] have been designed by using av ariety of selfassembling or templated reactions.A mong those,awide family of polynuclear cage-like metallasilsesquioxanes (CLMSs) architectures with interesting structural topologies [2] and important catalytic activity (e.g.i ne poxidation, oxidation and polymerization) [3] has been synthesized through ar eaction involving transition-metal ions and silsesquioxane [RSiO 1.5 ] n ligands.S urprisingly,e xamples of cage-like architectures involving another metalloid close to silicon, namely germanium, are scarce despite the great potential of this element in organometallic chemistry.T oour knowledge there is only aseries of compounds obtained from germasesquioxane [RGeO 1.5 ] 2 (R = HOOCCH 2 CH 2 )and various cations. [4] Their hydrothermal synthesis requires relatively hard conditions consisting of several days of reactions at 110 8 8C. It is worth mentioning that to date focus has only been on the synthesis,t hermogravimetric analysis,l uminescence, and sorption properties of these architectures and no investigation of the catalytic activity of metallagermanates has been reported.Herein, we report an alternative and simplified synthetic approach to design aseries of unprecedented individual cagelike metallagermsesquioxanes under mild conditions.I n addition, the catalytic activity and magnetic properties of the metallagermsesquioxanes will be discussed.Thes ingle crystals of Fe,Na-phenylgermsesquioxane [(Ph 5 Ge 5 O 10 ) 3 Fe 6 (OH) 3 (O)Na 2 ]·(EtOH) 2 ·H 2 O 1 (10 %y ield) were obtained by ar eaction between phenyltrimethoxygermane PhGe(OMe) 3 ,N aOH and anhydrous FeCl 3 in ethanol with further crystallization. Thea ddition of N-containing ligands,s uch as phenanthroline,b ipyridine,o rn eocuproine to this reaction allowed us to isolate complexes

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“…Polyhedral oligomeric silsesquioxanes (POSS) are ac lass of cage-like siloxanes. [13][14][15] Tri-silanol-containing POSS molecules (Figure 1, 1a-b)c ontain seven silicon atoms in a" cube missing ac orner" configuration (R 7 O 9 Si 7 (OH) 3 )a nd have received interest due to their "hybrid properties", possessing inorganics iloxane linkages (SiÀOÀSi), silanols (SiÀOH), and organic groups (R). [16,17] In addition, recent applications of POSS-triols include composites, [18][19][20] nanostructures, [21,22] and films.…”

Section: Introductionmentioning

confidence: 99%

Kinetic and Binding Studies Reveal Cooperativity and Off‐Cycle Competition for H‐Bonding Catalysis with Silsesquioxane Silanols

Jagannathan

Diemoz

Targos

et al. 2019

Chemistry A European J

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The catalytic activity, kinetics, and quantification of H‐bonding ability of incompletely condensed polyhedral oligomeric silsesquioxane (POSS) silanols are reported. POSS‐triols, a homogeneous model for vicinal silica surface sites, exhibit enhanced H‐bonding compared with other silanols and alcohols as quantified using a 31P NMR probe. Evaluation of a Friedel–Crafts addition reaction shows that phenyl‐POSS‐triol is active as an H‐bond donor catalyst whereas other POSS silanols studied are not. An in‐depth kinetic study (using RPKA and VTNA) highlights the concentration‐dependent H‐bonding behavior of POSS‐triols, which is attributed to intermolecular association forming an off‐cycle dimeric species. Binding constants provide additional support for reduced H‐bond ability at higher concentrations, which is attributed to competitive association. POSS‐triol self‐association disrupts H‐bond donor abilities relevant for catalysis by reducing the concentration of active monomeric catalyst.

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Modern concepts and methods in the chemistry of polyhedral metallasiloxanes

Cited by 82 publications

References 163 publications

Palanquin-Like Cu4Na4 Silsesquioxane Synthesis (via Oxidation of 1,1-bis(Diphenylphosphino)methane), Structure and Catalytic Activity in Alkane or Alcohol Oxidation with Peroxides

Palanquin-Like Cu4Na4 Silsesquioxane Synthesis (via Oxidation of 1,1-bis(Diphenylphosphino)methane), Structure and Catalytic Activity in Alkane or Alcohol Oxidation with Peroxides

Cage‐like Fe,Na‐Germsesquioxanes: Structure, Magnetism, and Catalytic Activity

Kinetic and Binding Studies Reveal Cooperativity and Off‐Cycle Competition for H‐Bonding Catalysis with Silsesquioxane Silanols

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