Reversible C=C Bond Activation by an Intramolecularly Coordinated Antimony(I) Compound

Abstract

The reaction of N,C,N‐chelated stibinidene ArSb (1) (Ar=C6H3‐2,6‐(CH=NtBu)2) with selected N‐alkyl/aryl‐maleimides RN(C(O)CH)2 (R=Me, tBu, Ph) gave the addition products with bridged bicyclic [2.2.1] structure containing an antimony atom at the bridgehead position, fused with a 6‐membered benzene and a 5‐membered N‐alkyl/aryl‐pyrrolidine ring. These compounds were completely characterized. More importantly, additional studies showed that these reactions are reversible in solution, thereby representing an unprecedented reversible activation of a C=C bond by an antimony(I) compound.

Recent developments in the chemistry of non-trigonal pnictogen pincer compounds: from bonding to catalysis

“…Furthermore, the reactivity towards maleimides was studied. 95 The C]C double bonds adds along the Sb-N bond giving the [4 + 2] cycloaddition product 37. In solution both species are in equilibrium as determined by EXSY NMR studies.…”

Hydrostibination of Alkynes: A Radical Mechanism

“…We therefore conclude that a radical mechanism is at play (Figure 2 Notably, the antimony centres in mechanism D undergo a rare example of redox cycling between the +2 and +3 oxidation states while traversing the reaction coordinate. 50,73,74 Nevertheless, the mechanism of the alkyne hydrostibination clearly shows some important similarities with analogous radical processes that have been proposed for catalytic hydrometallation involving gold and tin hydrides. 19,75 Attempts to intercept and redirect the radical species proposed herein towards other productive pathways are underway to rationally develop new reactivity modes involving antimony complexes.…”

(N),C,N‐Coordinated Heavier Group 13–15 Compounds: Synthesis, Structure and Applications

“…This is not only the question of their spectacular structure. More importantly their capability in activation of organic substrates in a cooperative mechanism involving both ligand backbone and the central atom E is of particular interest as above shown for N,C,N ‐chelated pnictnidenes . Fine tuning of such systems is expected to allow activation of other small molecules, that could be only hardly attacked without this close cooperation between ligand and central atom E. Searching for systems that will be able to do this in a reversible manner is also a key factor for their possible application in catalysis.…”

“…These findings supported further development of this field of chemistry. Most recently, it was shown that the Ar N=C=N Sb is also able to activate C=C double bond in selected maleimides (Scheme ) . In solution, they tend to decompose back to the starting materials and upon heating of the samples the starting compounds are recovered completely.…”