Reactivity of Dialumane and “Dialumene” Compounds toward Alkenes

Abstract

The reactions of dialumane [L(thf)Al-Al(thf)L] (1, L=[{(2,6-iPr2C6H3)NC(Me)}2](2-)) with stilbene and styrene afforded the oxidation/insertion products [L(thf)Al(CH(Ph)-CH(Ph))AlL] (2) and [L(thf)Al(CH(Ph)-CH2)Al(thf)L] (3), respectively. In the presence of Na metal, precursor 1 reacted with butadienes, possibly through the reduced "dialumene" or the "carbene-like" :AlL species, to yield aluminacyclopentenes [LAl(CH2C(Me)=C(Me)CH2)Na]n (4 a) and [Na(dme)3][LAl(CH2C(Me)=CHCH2)] (4 b, dme=dimethoxyethane) as [1+4] cycloaddition products, as well as the [2+4] cycloaddition product 1,6-dialumina-3,8-cyclodecadiene, [{Na(dme)}2][LAl(CH2C(Me)=C(Me)CH2)2AlL] (5). The possible mechanisms of the cycloaddition reactions were studied by using DFT computations.

Cycloaddition versus Cleavage of the C=S Bond of Isothiocyanates Promoted by Digallane Compounds with Noninnocent α‐Diimine Ligands

“…It shows unusualm onodentate coordination in the amido-imine form, in which the N(1) atom is bondedt oG aa nd the N(2) atom is twisted away to interact with an Na + ion. This monodentate coordination mode of an a-diiminew as observed previously in ad ialuminumh exynide complex, in which addition of two (2) 2.8908 (9), Ga(1)ÀS(1) 2.2590 (16), Ga(1)ÀS (2) 2.2210 (16), Ga(1)ÀN(1) 1.983(5), Ga(1)ÀN(2) 1.972(5), Ga(2)ÀN(3) 1.944(5), Ga(2)ÀN(4) 1.946(5), N(1)ÀC(1) 1.336 (7), N(2)ÀC(2) 1.352(8),C(1)À C(2) 1.431 (9), N(3)ÀC(37) 1.369(8), N(4)ÀC(38) 1.391 (7),C(37)ÀC(38) 1.389 (8); Ga(2)-S(1)-Ga(1) 79.83(5),N (1)-Ga(1)-S(1) 113.11(14), N(2)-Ga(1)-S(1) 114.40(15), N(2)-Ga(1)-N(1) 85.8 (2), Ga(1)-S(2)-Ga (2) (1)···Ga(1')2 .980, Ga(1)ÀN(1) 1.902(5), Ga(1)ÀS(1) 2.314 (2), Ga(1)ÀS (2) 2.267(2), Ga(1)ÀS(2')2 .254 (2), S(1)ÀC (29) 1.786 (7), N(3)ÀC (29) 1.270 (9), C(29)ÀC(1) 1.560 (9), C(1)ÀN(1) 1.472(8),C(2)ÀN(2) 1.287(8), C(1)ÀC (2) 1.560 (9), N(1)-Ga(1)-S(1)9 1.20 (2), Ga(1)-S(1)-C(29) 95.0(2), S(1)-C(29)-N(3) 124.2(6), Ga(1)-S(2)-Ga(A) 82.6(7). (')1 Àx,1Ày,1Àz.…”

“…α‐Diimine ligands proved to be successful in stabilizing a variety of low‐valent metal complexes, including group 13 metal–metal‐bonded compounds such as digallanes and dialumanes –. These complexes have shown promising reactivity towards various small molecules, such as alkynes, alkenes, disulfides, azobenzenes, phenazine, sulfur dioxide, and ketone derivatives . Further, the α‐diimines are redox‐active ligands that can be easily oxidized or reduced, can serve as electron reservoirs, and allow significant extension of the reactivity of metal complexes.…”

Gallium “Shears” for C=N and C=O Bonds of Isocyanates

“…The N‐hetero gallacyclopropane then rapidly dimerizes to give the 1,4‐digalla‐2,5‐diazacyclohexane derivative 6 , which is 40.1 kcal mol −1 lower in energy than the galla‐azacyclopropane. Although we failed to trap the N‐hetero cyclopropane for gallium, we previously characterized the related aluminacyclopentene, which was most likely formed through a [1+4] cycloaddition involving the monomeric LAl: intermediate . This type of oxidative addition reaction of unsaturated hydrocarbons is common for derivatives of heavier low‐valent Group 13 elements .…”

Cycloaddition of isoselenocyanates to sodium and magnesium metallacycles

“…Cycloadditions of iso(thio)cyanates to monomeric aluminum oxides and sulfides to give IV 20 and V 18 products (Scheme 1) are illustrative for this type of reactions. Cycloadditions of unsaturated substrates at alylene, gallylene and other :ML carbenoid centers form a third group of such reactions ( VI 23 and VII , 24,25 Scheme 1). 26–29…”