Hypercoordinate compounds of the group 14 elements containing κn-C,N-, C,O-, C,S- and C,P-ligands

Khan, Aman; Foucher, Daniel A.

doi:10.1016/j.ccr.2015.10.009

Cited by 30 publications

(25 citation statements)

References 97 publications

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“…To understand the “design rules” for constructing a wider variety of stable polystannanes, the role of ligands in hypercoordination must be understood. Synergistic push–pull interactions, such as those defined by three‐center–four‐electron (3c–4e − ) hypercoordination arrangements, have been known for at least 50 years between later Group 14 elements (Si, Ge, Sn, Pb), electron‐rich N, P, O, S donor atoms and axially coordinated electron‐withdrawing substituents (Cl − , Br − , I − ) . X‐ray structural data for several of these Sn species reveals additional donor–ligand coordination to Group 14 elements along with an elongation of the ligand–metal bond trans to the donating group .…”

Section: Introductionmentioning

confidence: 67%

“…Synergistic push-pull interactions, such as those defined by three-center-four-electron (3c-4e À )h ypercoordination arrangements, have been known fora t least 50 years between later Group 14 elements (Si, Ge, Sn, Pb), electron-rich N, P, O, Sd onor atoms and axially coordinated electron-withdrawings ubstituents (Cl À ,B r À ,I À ). [22,23] X-ray structuraldata for several of these Sn speciesreveals additional donor-ligand coordinationt oG roup 14 elements along with an elongation of the ligand-metal bond trans to the donating group. [24][25][26][27][28][29][30][31] Hypercoordination to aS nc enteri st heorized to be the result of a2 e À donation from the formal p-orbital of the donating ligand into an empty non-bondingo rbital of Sn, which then simultaneously transfers electron density to an antibonding p-orbital of the electron-withdrawing substituent.…”

Section: Introductionmentioning

confidence: 97%

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Synthesis and Characterization of Readily Modified Poly(aryl)(alkoxy)stannanes by use of Hypercoordinated Sn Monomers

Pau

D’Amaral

Lough

et al. 2018

Chemistry A European J

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The synthesis and solid‐state molecular structures of two dichlorido(aryl)(alkyl) tin compounds, 5 and 8, both key intermediates to tunable polystannane architectures, are reported. The materials were further investigated by single‐crystal XRD and a DFT analysis of their preferential “open and closed” geometries. Conversion of said compounds to their dihydride analogues was undertaken, followed by their application as monomers for polystannane polymer synthesis. The properties of two asymmetrical polystannanes prepared by transition‐metal‐catalyzed dehydropolymerization of dihydrido(aryl)alkylstannanes (6 and 9) were investigated. The first product was the structurally simple, modest molecular weight, semi‐crystalline light‐ and moisture‐stable polystannane 10 with NMR (119Sn) evidence of prominent Sn←O hypercoordination along the polymer backbone. The second was the lower molecular weight, tosylated four‐coordinate polystannane 11 with no evidence of hypercoordination. Differential scanning calorimetry (DSC) of polymer 10 revealed a reversible semi‐crystalline nature, whereas an amorphous character was detected for polymer 11. Polystannane 10 was also found to be exceptionally stable to both moisture and light (>6 months) and a promising candidate for the design of readily modified (i.e., tunable) polystannane materials.

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Section: Introductionmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 97%

Synthesis and Characterization of Readily Modified Poly(aryl)(alkoxy)stannanes by use of Hypercoordinated Sn Monomers

Pau

D’Amaral

Lough

et al. 2018

Chemistry A European J

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“…The 1 HNMR spectra of 6 taken initially at t = 0, 6a nd 24 ha re shown in Figure S1, and display isomer ratios of 10:1, 4:1a nd 1:1, respectively.I nc ontrast, the corresponding 119 Sn NMR signals at t = 0, 6a nd 24 hs how no change in the tin resonance behaviour,a nd this value is typical of af our-coordinatet in dihydride species. [24] Further evidencef or the preferred geometrieso fc ompounds 3, 4 and 5 was obtained by single crystal X-ray diffraction studies. The 119 Sn NMR resonance for 3 is found at d = À100 ppm, av alue typical of tetrahedrally coordinated organotins.…”

Section: Nmr Spectroscopymentioning

confidence: 98%

“…In contrast, the mono (4),a nd dichloro (5)s pecies (Figures 3a nd Figure4)a re formally five-coordinate (4: t 5 = 0.85, 5: t 5 = 0.46) [26] and possess Sn···O distances of 2.775 and 2.729 ,i n line with other five-coordinate Sn species that have ad ative oxygen interaction. [24] Scheme3.Stepwise chlorination of 3 to 4 and 5,and hydrogenationt o6. Metal-free dehydrocoupling of 6…”

Section: Nmr Spectroscopymentioning

confidence: 99%

Proof of Concept Studies Directed Towards Designed Molecular Wires: Property‐Driven Synthesis of Air and Moisture‐Stable Polystannanes

Pau

Lough

Wylie

et al. 2017

Chemistry A European J

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Polystannanes with azobenzene moieties designed to protect the Sn-Sn backbone from light- and moisture-induced degradation are described. The azo-stannyl precursor 3 (70 %) is converted in good yields (88-91 %) to the mono- (4), and dichlorostannanes (5), by sequential chlorination, followed by further reduction of 5 to the dihydride (6) using NaBH (78 %). All stannanes were characterised by NMR ( H, C, Sn) spectroscopy and HRMS; in addition, 3, 4 and 5 were structurally elucidated using X-ray diffraction analysis. Metal-free dehydrocoupling of 6 at RT leads exclusively to homopolymer (7-i) displaying an initial solution Sn NMR signal (δ=-196 ppm) that migrates to -235 ppm after 10 days (7-f). In contrast, metal-catalyzed dehydrocoupling of 6 in toluene at RT leads directly 7-f. Random co-polymers formed from 6 and (nBu) SnH at 4:1 (8 a) and 1:1 (8 b) ratios were compared to the alternating polystannane (9) prepared by the reaction of 6 with (nBu) Sn(NEt ) . DFT calculations of 3-6 indicate that hypercoordination at Sn is influenced by substituents and by solvation. Homopolymer 7 was found to have unprecedented moisture and light stability in the solid state for >6 months.

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“…The higher (penta‐ and hexa‐) coordinate silicon compounds can be considered as complexes, where the Si atom is typically surrounded by electronegative and/or multidentate ligands . The majority of these silicon complexes are charged species, outnumbering the few neutral penta‐ and hexacoordinate complexes …”

Section: Introductionmentioning

confidence: 99%

Selectively Tunable Domino Reaction of 1,3‐Diphenylpropane‐1,3‐dione on the Ethoxy‐Silicon Core

et al. 2020

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The reaction of (EtO)3SiCl with 1,3‐diphenylpropane‐1,3‐dione in dichloromethane yields an ionic hexacoordinate compound featuring three chelating 1,3‐diphenylpropane‐1,3‐dionato ligands as proven by its X‐ray structure and multinuclear NMR studies in a fast domino reaction. With a proper selection of the solvent (toluene) and the reaction time, the intermediates of the reaction sequence can be selectively obtained. With an excess of the starting chlorosilane and short reaction times, the tetracoordinate silane can be obtained by the replacement of the chloro substituent. This compound shows a dynamic behavior according to its 13C NMR spectrum, involving its pentacoordinate isomer, which is only slightly less stable according to DFT calculations. The hemilabile ethoxy group can easily be replaced by a further 1,3‐diphenylpropane‐1,3‐dionato ligand, yielding the neutral hexacoordinate silane with two chelators and two ethoxy groups, as characterized by X‐ray crystallography and multinuclear NMR studies.

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Hypercoordinate compounds of the group 14 elements containing κn-C,N-, C,O-, C,S- and C,P-ligands

Cited by 30 publications

References 97 publications

Synthesis and Characterization of Readily Modified Poly(aryl)(alkoxy)stannanes by use of Hypercoordinated Sn Monomers

Synthesis and Characterization of Readily Modified Poly(aryl)(alkoxy)stannanes by use of Hypercoordinated Sn Monomers

Proof of Concept Studies Directed Towards Designed Molecular Wires: Property‐Driven Synthesis of Air and Moisture‐Stable Polystannanes

Selectively Tunable Domino Reaction of 1,3‐Diphenylpropane‐1,3‐dione on the Ethoxy‐Silicon Core

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