25929-16-2Relevant academic research and scientific papers
Synthesis and the thermal and catalytic dehydrogenation reactions of amine-thioboranes
Robertson, Alasdair P. M.,Haddow, Mairi F.,Manners, Ian
body text, p. 8254 - 8264 (2012/09/22)
A series of trimethylamine-thioborane adducts, Me3N· BH2SR (R = tBu [2a], nBu [2b], iPr [2c], Ph [2d], C6F 5 [2e]) have been prepared and characterized. Attempts to access secondary and primary amine adducts of thioboranes via amine-exchange reactions involving these species proved unsuccessful, with the thiolate moiety shown to be vulnerable to displacement by free amine. However, treatment of the arylthioboranes, [BH2-SPh]3 (9) and C6F 5SBH2·SMe2 (10) with Me2NH and iPr2NH successfully yielded the adducts Me2NH· BH2SR (R = Ph [11a], C6F5 [12a]) and iPr 2NH·BH2SR (R = Ph [11b], C6F5 [12b]) in high yield. These adducts were also shown to be accessible via thermally induced hydrothiolation of the aminoboranes Me2N=BH 2, derived from the cyclic dimer [Me2N-BH 2]2 (13), and iPr2N=BH2 (14), respectively. Attempts to prepare the aliphatic thiolate substituted adducts R2NH·BH2SR′ (R = Me, iPr; R′ = tBu, nBu, iPr) via this method, however, proved unsuccessful, with the temperatures required to facilitate hydrothiolation also inducing thermal dehydrogenation of the amine-thioborane products to form aminothioboranes, R2N= BH(SR′). Thermal and catalytic dehydrogenation of the targeted amine-thioboranes, 11a/11b and 12a/12b were also investigated. Adducts 11b and 12b were cleanly dehydrogenated to yield iPr2N=BH(SPh) (22) and iPr2N=BH(SC6F5) (23), respectively, at 100 °C (18 h, toluene), with dehydrogenation also possible at 20 °C (42 h, toluene) with a 2 mol % loading of [Rh(μ-Cl)cod]2 in the case of the former species. Similar studies with adduct 11a evidenced a competitive elimination of H2 and HSPh upon thermolysis, and other complex reactivity under catalytic conditions, whereas the fluorinated analogue 12a was found to be resistant to dehydrogenation.
Thiaaza-arachno-pentaborane SNB3H2t-Bu3R
Mueller, Matthias,Englert, Ulli,Paetzold, Peter
, p. 1105 - 1108 (2007/10/03)
The azadiboridine (1) gives 1:1 adducts with the mercaptoboranes BH2(SR), which can be generated from their cyclotrimers by the action of THF.The adduct 4a (R = Ph), a nido cluster with an NB3 skeleton, forms an equilibrium with an adduct 5a, an arachno cluster with an SNB3 skeleton, whose S-bound ligand Ph is found in an endo position by an X-ray structural analysis.The equilibrium 4a ->/a Lewis acid-base reaction, which is electronically coupled to a reduction of a three-center to give a two-center ? bond.The reaction of 1 with BH2(SPr) gives the corresponding arachno cluster 5b only. - Keywords: Azadiboridine, tri-tert-butyl-; Mercaptoborane; Thiaaza-arachno-pentaborane, 1,4,5-tri-tert-butyl-2-organo-
