Mechanisms for the Reaction of Water, Butadiene, and Palladium Complex with 1,2-Dimetallacyclohexene (R2M═MR2, M = C, Si, Ge, Sn, Pb). A Theoretical Study

NH bond activation of ammonia and amines by ditetrelenes: key insights into the stereochemistry of nucleophilic addition

The NH bond activation of ammonia, primary and secondary amines by tetramesityldisilene and -digermene was investigated. In each case, a disilyl- or digermylamine was formed as the only product of amine addition. The mechanism of the addition of ammonia to tetramesityldisilene was computed and revealed a three-step reaction pathway: formation of the anti-ammonia-disilene adduct, inversion at the β-silicon, and syn-transfer of the proton to give the syn-product, where each step follows a distinct stereochemical course. Examination of the reaction landscape also revealed several additional insights: (a) that, in the initial step, the formation of the anti-oriented zwitterionic intermediate is kinetically more preferable than formation of the syn-oriented zwitterionic intermediate, (b) that intermolecular transfer of a proton is not energetically feasible in non-polar solvents, and (c) that the bulk of the substituents can have a profound effect on the stereochemical course of the reaction. With this detailed understanding, nucleophilic additions to ditetrelenes can be exploited in the future.

Mechanistic investigation of the reactivity of disilene with nitrous oxide: A DFT study

We have reported the mechanistic investigation of the reaction of N2O addition to disilene, trans-[(TMS)2N(η(1)-Me5C5)SiSi(η(1)-Me5C5)N(TMS)2] (1t), employing density functional theory (BP86/TZVP//BP86/SVP) calculations. The potential energy surfaces of the title reaction are broadly classified under three pathways. Pathway I deals with the direct N2O additions to 1t affording the trans-dioxadisiletane ring compound Pt whereas in the same pathway we report a different bifurcation route from intermediate 2t. This route portrays the isomerization of trans-monooxadisiletane species 2t prior to the second N2O addition, finally leading to the cis-isomeric product Pc. Different possibilities for isomerization of disilene 1t to 1c were studied in pathway II. The cis-disilene (1c) formed can subsequently react with two N2O molecules affording the cis-product Pc. Pathway III details the formation of silanone type intermediate 6, which subsequently combine with another silanone to afford loosely bound intermediates 7 and 8 respectively. The two separated silanone fragments in the isomeric intermediates 7 and 8 can then dimerizes to furnish the desired products. Among all the calculated potential energy surfaces, pathway III remains the most preferred route for disilene oxygenation under normal experimental condition. The present investigation about disilene reactivity will provide a deeper understanding on silylene chemistry and will exhibit promising applicability in main group chemistry as a whole.