New Carbon‐Carbon Bond Forming Reactions Promoted by Aluminyl and Alumoxane Anions: Introducing the Ethenetetraolate Ligand

[K{Al(NON Dipp )}] 2 (NON Dipp = [O(SiMe 2 NDipp) 2 ] 2– , Dipp = 2,6‐ i Pr 2 C 6 H 3 ) reacts with CS 2 to afford the trithiocarbonate species [K(OEt 2 )][Al(NON Dipp )(CS 3 )] 1 or the ethenetetrathiolate complex, [K{Al(NON Dipp )(S 2 C)}] 2 [ 3 ] 2 . The dimeric alumoxane [K{Al(NON Dipp )(O)}] 2 reacts with carbon monoxide to afford the oxygen analogue of 3 , [K{Al(NON Dipp )(O 2 C)}] 2 [ 4 ] 2 containing the hitherto unknown ethenetetraolate ligand, [C 2 O 4 ] 4–

Dihydrogen Activation by Lithium- and Sodium-Aluminyls

To date, aluminyl anions have been exclusively isolated as their potassium salts. We report herein the synthesis of the lithium and sodium aluminyls, M2[Al(NONDipp)]2 (M=Li, Na. NONDipp=[O(SiMe2NDipp)2]2−; Dipp=2,6-iPr2C6H3). Both compounds crystallize from non-coordinating solvent as “slipped” contacted dimeric pairs with strong M⋅⋅⋅π(aryl) interactions. Isolation from Et2O solution affords the monomeric ion pairs (NONDipp)Al-M(Et2O)2, which contain discrete Al−Li and Al−Na bonds. The ability of the full series of Li, Na and K aluminyls to activate dihydrogen is reported

Double insertion of CO2 into an Al–Te multiple bond

We report the [Al(NONDipp)(Te)(THF)]− anion containing a terminal aluminium telluride bond. DFT calculations confirm appreciable Al–Te multiple bond character and reaction with CO2 proceeds via a double insertion to afford the previously unknown tellurodicarbonate ligand.<br/

Combined experimental and computational investigations of rhodium-catalysed C-H functionalisation of pyrazoles with alkenes

Detailed experimental and computational studies have been carried out on the oxidative coupling of the alkenes C(2)H(3)Y (Y=CO(2)Me (a), Ph (b), C(O)Me (c)) with 3-aryl-5-R-pyrazoles (R=Me (1 a), Ph (1 b), CF(3) (1 c)) using a [Rh(MeCN)(3)Cp*][PF(6)](2)/Cu(OAc)(2)⋅H(2)O catalyst system. In the reaction of methyl acrylate with 1 a, up to five products (2 aa–6 aa) were formed, including the trans monovinyl product, either complexed within a novel Cu(I) dimer (2 aa) or as the free species (3 aa), and a divinyl species (6 aa); both 3 aa and 6 aa underwent cyclisation by an aza-Michael reaction to give fused heterocycles 4 aa and 5 aa, respectively. With styrene, only trans mono- and divinylation products were observed, whereas with methyl vinyl ketone, a stronger Michael acceptor, only cyclised oxidative coupling products were formed. Density functional theory calculations were performed to characterise the different migratory insertion and β-H transfer steps implicated in the reactions of 1 a with methyl acrylate and styrene. The calculations showed a clear kinetic preference for 2,1-insertion and the formation of trans vinyl products, consistent with the experimental results

Controlling Al–M Interactions in Group 1 Metal Aluminyls (M = Li, Na, and K). Facile Conversion of Dimers to Monomeric and Separated Ion Pairs

The aluminyl compounds [M{Al(NONDipp)}]2 (NONDipp = [O(SiMe2NDipp)2]2–, Dipp = 2,6-iPr2C6H3), which exist as contacted dimeric pairs in both the solution and solid states, have been converted to monomeric ion pairs and separated ion pairs for each of the group 1 metals, M = Li, Na, and K. The monomeric ion pairs contain discrete, highly polarized Al–M bonds between the aluminum and the group 1 metal and have been isolated with monodentate (THF, M = Li and Na) or bidentate (TMEDA, M = Li, Na, and K) ligands at M. The separated ion pairs comprise group 1 cations that are encapsulated by polydentate ligands, rendering the aluminyl anion, [Al(NONDipp)]− “naked”. For M = Li, this structure type was isolated as the [Li(TMEDA)2]+ salt directly from a solution of the corresponding contacted dimeric pair in neat TMEDA, while the polydentate [2.2.2]cryptand ligand was used to generate the separated ion pairs for the heavier group 1 metals M = Na and K. This work shows that starting from the corresponding contacted dimeric pairs, the extent of the Al–M interaction in these aluminyl systems can be readily controlled with appropriate chelating reagents

Stabilisation of the [SiH6]2– Anion within a Supramolecular Assembly

The hypercoordinate [SiH6]2– anion is not stable in solution. Here, we report the room temperature, solution stable molecular [SiH6]2– complex, [{KCa(NON)(OEt2)}2][SiH6] (NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tertbutyl-9,9-dimethyl-xanthene)), where the [SiH6]2– anion is stabilised within a supramolecular assembly that mimics the solid-state environment of the anion in the lattice of K2SiH6. Solution-state reactivity of the complex towards carbon monoxide, benzaldehyde, azobenzene and acetonitrile is reported, yielding a range of reduction and C–C coupled products