The Reactions of Aryl Tin(II) Hydrides {Ar^iPr6Sn(μ-H)}₂ (Ar^iPr6 = C₆H₃-2,6-(C₆H₂-2,4,6-ⁱPr₃)₂) and {Ar^iPr4Sn(μ-H)}₂ (Ar^iPr4 = C₆H₃-2,6-(C₆H₃-2,6-ⁱPr₂)₂) with Aryl Alkynes: Substituent Dependent Structural Isomers

Abstract

The reactions of the aryl tin(II) hydrides {Ar iPr6 Sn(μ-H)} 2 (Ar iPr6 = C 6 H 3 -2,6-(C 6 H 2 -2,4,6-i Pr 3 ) 2 ) and {Ar iPr4 Sn(μ-H)} 2 (Ar iPr4 = C 6 H 3 -2,6-(C 6 H 3 -2,6-i Pr 2 ) 2 ) with aryl alkynes were investigated. Reaction of {Ar iPr6 Sn(μ-H)} 2 and {Ar iPr4 Sn(μ-H)} 2 with 2 equiv of diphenyl acetylene, PhCCPh, afforded the aryl alkenyl stannylenes Ar iPr6 SnC(Ph)-C(H)Ph ( 1) and Ar iPr4 SnC(Ph)C(H)Ph (2). In contrast, the analogous reactions of {Ar iPr6 Sn(μ-H)} 2 with 2 equiv of phenyl acetylene, HCCPh, afforded a high yield of the cis-1,2 addition product Ar iPr6 (H)SnC(H)C(Ph)Sn(H)Ar iPr6 (3), which has a four-membered Sn 2 C 2 core structure comprised of two Sn−Sn bonded Sn(H)Ar iPr6 units bridged by a −C(H)C(Ph)− moiety. The corresponding reaction of the less bulky hydride {Ar iPr4 Sn(μ-H)} 2 with 2 equiv of phenyl acetylene leads to Ar iPr4 SnC(H)C(Ph)Sn(H) 2 Ar iPr4 (4) which unlike 3 has no Sn−Sn bonding. Instead, the tin atoms are connected solely by a −C(H)C(Ph)− moiety. Each tin atom carries a Ar iPr4 substituent but one is also substituted by two hydrogens. The difference in behavior between PhCCPh and HCCPh is attributed mainly to the difference in steric bulk of the two substrates. The different products 3 and 4 are probably a consequence of the difference in size and dispersion force interactions of the Ar iPr6 and Ar iPr4 substituents. Compounds 1−4 were characterized by 1 H, 13 C, and 119 Sn NMR, UV−vis, and IR spectroscopy and structurally by X-ray crystallography.

Tetryl‐Tetrylene Addition to Phenylacetylene

“…The olefinic proton Ge−CH=C exhibits a signal at 6.79 ppm, comparable to signals found for olefinic protons in triorganogermyl substituted olefins [8] . The 119 Sn NMR signal of the arylvinylstannylene 4 with 1630 ppm is characteristic of a monomeric stannylene and can be compared with the signal found for the diphenylacetylene insertion product of [Ar*SnH] 2 (1573.9 ppm) [2i] …”

“…Details of the crystal structure analysis are placed in the Supporting Information. Vinylstannylenes were already presented in the literature and exhibit Sn−C(vinyl) distances of 2.2020(17) and 2.198(3) Å [2i] . The Sn−C(vinyl) distance in 4 of 2.214(4) Å is only slightly longer.…”

“…Alkyne addition product Z ‐ 8 was also characterized by NMR spectroscopy. The 1 H and 119 Sn NMR signals of the SnH 2 unit were found at 4.17 ppm and −353 ppm and can be compared with the signals found for the SnH 2 unit in the alkyne addition product [Ar*SnCHCPhSnH 2 Ar*] synthesized in reaction between the dimeric tin hydride [(Ar*SnH) 2 ] and phenylalkyne (5.05 ppm, −324 ppm) [2i] . The signal which was found in the 207 Pb NMR spectrum for plumbylene Z ‐ 8 (6436 ppm) is indicative of a monomeric plumbylene and lies in the range of signals found for plumbylenes 2 (9183 ppm) and 3 (8885 ppm) (see Scheme 1 for 2 and 3 ) [5f, 11] …”

“…investigated the reaction of a low valent organotin hydride with phenylalkyne and characterized a syn ‐addition of a stannylstannylene at the alkyne moiety [2i] . These hydrides are very reactive compounds, which exhibit hydroelementation reactions, activation of small molecules, and were shown to act as catalysts in organic transformation reactions [2i, 4] . We are interested in the hydride chemistry of the heavy Group 14 elements and have reported recently the deprotonation of organoelement trihydrides of germanium and tin [5] .…”

Reactivity of organogermanium and organotin trihydrides

“…[6][7][8][9] These highly reactive compounds show hydroelementation reactions, act as catalysts in organic transformations and activate small molecules. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] In the series of organoelement(IV) hydrides of germanium and tin higher stability was observed with an increasing number of organic substituents. 29 Thus, tributyltin hydride is a well-known reagent in organic chemistry.…”