Diarylstannylene Activation of Hydrogen or Ammonia with Arene Elimination

Abstract

Treatment of the stannylenes SnAr'2 (Ar' = C6H3-2,6(C6H3-2,6-Pri2)2), SnAr2# (Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2, or Sn{N(SiMe3)2}2 with H2, D2, or NH3 under identical, mild (1 atm, 65 degrees C) conditions showed that SnAr2' reacted readily to afford the products {Ar'Sn(mu-H)}2, {Ar'Sn(mu-D)}2, or {Ar'Sn(mu-NH2)}2 with elimination of Ar'H or Ar'D. The less crowded stannylenes SnAr2# and Sn{N(SiMe3)2}2 were recovered unreacted. The differences in reactivity were accounted for in terms of the n-p energy separations which is lowest in the case of AnAr2'. The low energy separation in SnAr' is consistent with enhanced singlet diradical character of the ground state which increases its reactivity.

Stable singlet carbenes as mimics for transition metal centers

“…27,28 These reactions occurred under relatively mild conditions; however, depending on the nature of the aryl substituents, subsequent arene elimination sometimes occurs.…”

“…In the case of stannylenes 8 , the addition of NH 3 results in the formation of dimeric derivative 9 with concomitant elimination of an arene, as observed for the activation of H 2 by this species. 27 …”

Synthesis, Reactivity, and Computational Analysis of Halophosphines Supported by Dianionic Guanidinate Ligands

“…1 Several years later he also showed the addition of dihydrogen to distannynes to give tin(II) hydrides. [2][3][4][5][6][7][8] A notable surge in the reported reactivity of "frustrated Lewis pairs" (FLP) was kickstarted by Stephan et al, where they reported metalfree reversible hydrogen activation by the unquenched reactivity of a phosphine-borane ((C6H2Me3)2P(C6F4)B(C6F5)2), which features a Lewis acidic boron and Lewis basic phosphorus. 9 Since then, many different FLP systems have been developed 10 and reactivity with a variety of substrates has been observed, including B-H bonds, 11 CO2, 12,13 unsaturated bonds 10 and even catalytic, metal-free hydrogenation.…”

Hydrogenation and Dehydrogenation of Dinuclear Boron‐ and Gallium Hydrides: Quantum Chemical Calculations and Experiments

“…Even more, for some bond activations the main-group element compounds might even outperform transitionmetal complexes. For example, oxidative insertion into an NÀH bond of NH 3 , thus opening the door to hydramination reactions, is highly unusual for transition-metal complexes due to the formation of a strong and stable metal-NH 3 coordination bond [1], and was shown to function well with special main-group element compounds [2][3][4]. A recent review by P. P. Power, entitled Main-group elements as transition metals, summarized some spectacular findings [5], with dihydrogen activation being at the very center of these developments.…”

“…Finally, the diarylstannylene SnAr 2 reacts with H 2 gas at 60-70 C to give [ArSn (m-H)] 2 and ArH [9]. 3) Subvalent dimeric main-group element compounds: In the case of the molecules of this category, H 2 adds oxidatively to an E-E bond (E ¼ main-group element).…”