38178-34-6Relevant academic research and scientific papers
Room-Temperature Palladium(II)-Catalyzed Direct 2-Arylation of Indoles with Tetraarylstannanes
Liu, Yuxia,Wang, Chao,Huang, Linjuan,Xue, Dong
supporting information, p. 1613 - 1618 (2020/09/15)
A palladium(II)-catalyzed direct 2-arylation of indoles by tetraarylstannanes with oxygen (balloon) as the oxidant at room temperature has been developed. Various tetraarylstannanes can be employed as aryl sources for 2-arylation of indoles in up to 89% yield, providing a practical and efficient catalytic protocol for accessing 2-arylindoles.
Tuning the Optoelectronic Properties of Stannoles by the Judicious Choice of the Organic Substituents
Ramirez Y Medina, Isabel-Maria,Rohdenburg, Markus,Mostaghimi, Farzin,Grabowsky, Simon,Swiderek, Petra,Beckmann, Jens,Hoffmann, Jonas,Dorcet, Vincent,Hissler, Muriel,Staubitz, Anne
supporting information, p. 12562 - 12575 (2018/10/20)
Stannoles are organometallic rings in which the heteroatom is involved in a form of conjugation that is called σ?-π? conjugation. Only very little is known about how the substituents on the Sn atom or substituents on the stannole ring determine the optoelectronic properties of these heterocycles. In this work, this question has been studied experimentally and theoretically. Calculations of optimized equilibrium geometries, energy gaps between the highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs), and of the absorption spectra of a wide range of compounds were performed. The computational data showed that the substituents on the Sn atom influence the optoelectronic properties to a lower extent than the substituents in the 2 and 5 positions of the ring. These substituents in the 2 and 5 positions of the stannole ring can also have a strong influence on the overall planarity of the structure, in which mesomeric effects can play a substantial role only if the structure is planar. Thus, only structures with a planar backbone are of interest in the context of tuning the optoelectronic properties. These were selected for the experimental studies. On the basis of this information, a series of six novel stannoles was synthesized by the formation of a zirconium intermediate and subsequent transmetalation to obtain the tin compound. The calculated electronic HOMO-LUMO energy gaps varied between 2.94 and 2.68 eV. The measured absorption maxima were located between 415 and 448 nm compared to theoretically calculated values ranging from 447 nm (2.77 eV) to 482 nm (2.57 eV). In addition to these optical measurements, cyclic voltammetry data could be obtained, which show two reversible oxidation processes for three of the six stannoles. With this study, it could be demonstrated how the judicious choice of the substituents can lead to large and predictable bathochromic shifts in the absorption spectra.
push-push and push-pull polystannanes
Dhindsa,Jacobs,Lough,Foucher
, p. 14094 - 14100 (2018/10/20)
The synthesis and characterization of polystannanes with push or pull moieties attached to the tin backbone are described. Precursor tetra aryl- (1, 2) stannanes were converted to mono- (3) and dichloro- (4, 5) stannanes by either sequential chlorination or by redistribution reactions with SnCl4. Compounds 4 and 5 were transformed to polymerisable tin dihydride monomers 6 and 7 using a large excess (10×) of NaBH4. Homopolymer 8 with electron donating aryl substituents (p-MeOC6H4-) was synthesized by dehydrogenative polymerization using Wilkinson's catalyst. Attempts to prepare the homopolymer 9 with electron withdrawing aryl substituents (p-CF3C6H4-) from the dehydrocoupling of 7 using similar conditions led only to the formation of low molecular weight oligomeric species. Two alternating polymers, 10 and 11, were synthesized by condensation polymerization of (n-Bu)2Sn(NEt2)2 with monomers 6 or 7. The first was a push-push alternating polymer, 10, comprised of a repeating unit consisting of two different electron donating groups (p-MeOC6H4-, n-Bu) at neighboring tin centres. The second was a push-pull alternating polymer, 11, bearing both an electron donating group (n-Bu) and a strongly electron withdrawing substituent (p-CF3C6H4-) at neighboring tin atoms. All small molecule stannanes and tin-containing polymers were characterized by NMR (1H, 13C, 119Sn, and where required 19F) spectroscopy, MS or EA. The absolute molecular weights of tin polymers (8, 10, 11) were determined by triple detection GPC and in the range of 1.07 × 104 to 1.95 × 104 Da. Rapid photodegradation of polymers was observed by UV-Vis spectroscopy, with a slower degradation observed for the push-pull polymer, 11, compared to the push-push polymer, 10.
Formation of pentaorganostannates from Bis(2-bromo-2′-biphenyl) stannanes and tert-butyllithium upon substitution of alkyl and aryl groups on tin atoms
Saito, Masaichi,Imaizumi, Sanae,Tajima, Tomoyuki
, p. 2153 - 2157 (2010/09/06)
The reaction, of bis(2-brom.o-2'-biphenyl)stannanes 1 with tert-butyllithium in the presence of diaryl- and dialkyldichlorostannanes leads to the extrusion of aryl and alkyl groups on the tin atom, affording 9-stannafluorene derivatives bearing biphenyl g
The Ullmann coupling reaction: A new approach to tetraarylstannanes
Shaikh, Nadim S.,Parkin, Sean,Lehmler, Hans-Joachim
, p. 4207 - 4214 (2008/10/09)
Several iodobenzenes form tetraarylstannanes, in addition to other products, under reaction conditions typically employed for the Ullmann reaction, i.e., activated copper bronze (a copper-tin alloy) and 7 days at 230°C. The isolated yields of the tetraarylstannanes were low to good (8-58%). Significantly higher yields (54-64%) of tetraphenylstannane were obtained by the direct reaction of iodobenzene with an excess of tin powder (iodobenzene: tin = 1:1 w/w) under the same conditions. Crystal structure analysis reveals that tetrakis(4-carbomethoxyphenyl)stannane crystallizes in a tetragonal space group and has 4 symmetry, which is the case for many symmetrical tetraarylstannanes. However, tetrakis(2,4-dichlorophenyl)stannane, tetrakis(3,4-dichlorophenyl)stannane, and tetrakis(2,4-dimethylphenyl)stannane do not crystallize in a tetragonal space group and do not have real 4 symmetry.
Palladium(II)- and rhodium(III)-catalyzed carbonylation reaction of aryltin compounds
Uemura,Ohe,Motofusa,Ohe
, p. 1343 - 1348 (2007/10/03)
The Pd(II)- and Rh(III)-catalyzed carbonylation reaction of several aryltin compounds, i.e., tetraphenyltin (Ph4Sn), in acetonitrile (MeCN) and acetic acid was studied. The reaction of Ph4Sn with 1 atm of CO in the presence of a stoichiometric amount of Pd(II) salt was performed to confirm whether more than one of the four phenyl groups could be transferred to the products. To accelerate the carbonylation, LiCl was added, thus, producing benzophenone, benzoic acid, and a small amount of biphenyl as organic products, but only one of the four phenyl groups was transferred to the products. For the Rh(II)-mediated and -catalyzed carbonylation of aryltin compounds in MeCN, benzophenone was mainly produced together with benzoic acid and biphenyl. Seventy-five percent of the four phenyl groups were transferred to the products. The product yield was > 100% based on the amount of Rh(III) chloride used, showing that the Rh(III) salt itself worked as a catalyst without reoxidant addition. Thus, More than one of two, three, or four aryl groups of aryltin compounds, and almost all of them in some cases, could be transferred to the products in this catalytic carbonylation.
Ueber Tetraaryl-Methan-Analoga in der Gruppe 14.III. Ar4Sn/Pb (Ar=Ph, p-, m-, o-Tol, 2,4-Xyl und 2,5-Xyl): Gegenueberstellung von Bindungslaengen und Winkeln, von NMR chemischen Verschiebungen und Kopplungskonstanten und von Schwingungsdaten
Schneider-Koglin, Claudia,Mathiasch, Bernd,Draeger, Martin
, p. 25 - 32 (2007/10/02)
The title compounds have been synthesized Grignard reactions or pyrolysis of diplumbanes respectively.The crystal structures of m-Tol4Pb and Ph4Pb (redetermination) have been determined.All eight compounds (Ph/Tol)4(Sn/Pb) are S4 symmetric and contracted along this unique axis.The 13C-NMR chemical shifts and the couplings 1J(119Sn/207Pb-13C) as well depend additively upon the methyl substituents.The ratios 1K(207Pb-13C):1K(119Sn-13C) of the reduced coupling constants are all near to 1.61; a comparison with values from the literature for alkyl, alkenyl and alkinyl substituents is given.The ratio δ(207Pb):δ(119Sn) results in 2.28.IR (700 down to 200 cm-1) and Raman (700 down to 50 cm-1) data are given.Key words: Tin; Lead; Group 14; Vibrational data; Nuclear magnetic resonance; Crystal structure
Studies in aryltin chemistry III*. Crystal and molecular structures of tetra(p-methoxyphenyl)tin(IV) and tetra(p-methylthiophenyl)tin(IV)
Wharf, Ivor,Simard, Michael G.
, p. 85 - 94 (2007/10/02)
Tetrakis(p-methylthiophenyl)tin(IV) (A) and tetrakis(p-methoxyphenyl)tin(IV) (B) have been prepared and their vibrational spectra (400-100 cm-1) and X-ray crystal structures are reported.Both compounds are tetragonal with space group I4, Z = 2.For (A), a = b = 13.553(4), c = 7.442(2) Angstroem, and for (B), a = b =14.180(4), c = 6.303(2) Angstroem both at 173 K.Both structures were solved by the direct method and refined by full-matrix least squares calculations to R = 0.040, 767 observed reflections for A, and to R = 0.019, 721 observed reflections for B.Both molecules have 4 molecular symmetry with the CH3S or CH3O groups in the all-exo conformation almost coplanar with the phenyl rings.Increasing size of the para-substituent as CH3 is replaced by CH3O and then CH3S causes a decrease in d(Sn-C) from 2.147(6) to 2.136(4) and 2.123(7) Angstroem ascribed to increased intermolecular repulsions in the isomorphous close-packed structures.
