41825-39-2Relevant articles and documents
A utility for organoleads: Selective alkyl and aryl group transfer to tin
Arias-Ugarte, Renzo N.,Pannell, Keith H.
, p. 1703 - 1708 (2018)
Me4Pb and Ph4Pb readily transfer methyl or phenyl groups to an equivalent molar ratio of tin(iv) chlorides in the order SnCl4 > MeSnCl3 > Me2SnCl2 > Me3SnCl, often in a selective manner. Me3PbCl and Ph3PbCl specifically transfer a single methyl/phenyl group under the same reaction conditions to produce recovered yields in >75%. Specific transfer of 2 methyl groups from PbMe4 can be achieved at elevated temperatures and/or a 2:1 molar ratio Pb:Sn.
Incorporating methyl and phenyl substituted stannylene units into oligosilanes. The influence on optical absorption properties
Stella, Filippo,Marschner, Christoph,Baumgartner, Judith
, (2018/01/17)
Molecules containing catenated heavy group 14 atoms are known to exhibit the interesting property of σ-bond electron delocalization. While this is well studied for oligo- and polysilanes the current paper addresses the UV-absorption properties of small tin containing oligosilanes in order to evaluate the effects of Sn-Si and Sn-Sn bonds as well as the results of substituent exchange from methyl to phenyl groups. The new stannasilanes were compared to previously investigated oligosilanes of equal chain lengths and substituent pattern. Replacing the central SiMe2 group in a pentasilane by a SnMe2 unit caused a bathochromic shift of the low-energy band (λmax = 260 nm) of 14 nm in the UV spectrum. If, instead of a SnMe2, a SnPh2 unit is incorporated, the bathochromic shift of 33 nm is substantially larger. Keeping the SnMe2 unit and replacing the two central silicon with tin atoms causes shift of the respective band (λ = 286 nm) some 26 nm to the red. A similar approach for hexasilanes where the model oligosilane [(Me3Si)3Si]2(SiMe2)2 (λmax = 253 nm) was modified in a way that the central tetramethyldisilanylene unit was exchanged for a tetraphenyldistannanylene caused a 50 nm bathochromic shift to a low-energy band with λmax = 303 nm.
Direct Detection, Dimerization, and Chemical Trapping of Dimethyl- and Diphenylstannylene from Photolysis of Stannacyclopent-3-enes in Solution
Duffy, Ian R.,Leigh, William J.
, p. 5029 - 5044 (2015/11/09)
Dimethyl- and diphenylstannylene (SnMe2 and SnPh2, respectively) have been successfully detected and characterized in solution. The stannylenes were generated by photolysis of 1,1,3-trimethyl-4-phenyl- (2) and 3,4-dimethyl-1,1-diphenylstannacyclopent-3-ene (3), respectively, which have been shown to extrude the species cleanly and in high (0.6 2SnCl2) as the stannylene substrate. Laser flash photolysis of 2 and 3 in deoxygenated hexanes affords promptly formed transient absorptions assigned to SnMe2 (λmax = 500 nm; ε500 = 1800 ± 600 M-1 cm-1) and SnPh2 (λmax = 290, 505 nm; ε500 = 2500 ± 600 M-1 cm-1), respectively, which decay with absolute second-order rate constants within a factor of 2 of the diffusional limit in both cases. The decay of the stannylenes is accompanied by the growth of new transient absorptions ascribable to the corresponding dimers, the structures of which are assigned with the aid of DFT and time-dependent (TD) DFT calculations at the (TD)ωB97XD/6-31+G(d,p)C,H,O-LANL2DZdpSn level of theory. Dimerization of SnMe2 affords a species exhibiting λmax = 465 nm, which is assigned to the expected Sn=Sn doubly bonded dimer, tetramethyldistannene (Me2Sn=SnMe2, 16a), in agreement with earlier work. In contrast, the spectrum of the dimer formed from SnPh2 exhibits strong absorptions in the 280-380 nm range and a very weak absorption at 650 nm, on the basis of which it is assigned to phenyl(triphenylstannyl)stannylene (17b). The calculations suggest that 17b is formed via ultrafast rearrangement of a novel phenyl-bridged stannylidenestannylene intermediate (20), which can be formed either directly by "endo" dimerization of SnPh2 or by isomerization of the "exo" dimer, tetraphenyldistannene (16b); the predicted barriers for these rearrangements are consistent with the experimental finding that the observed product is formed at close to the diffusion-controlled rate. Absolute rate and equilibrium constants are reported for the reactions of SnMe2 and SnPh2 with Me2SnCl2 and methanol (MeOH), respectively, in hexanes at 25 °C.
