An aluminium telluride with a terminal Al=Te bond and its conversion to an aluminium tellurocarbonate by CO2 reduction

Facile access to dimeric heavier aluminium chalcogenides [(NHC)Al(Tipp)-µ-Ch]2 (NHC = IiPr (1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene, IMe4 (1,3,4,5-tetramethylimidazol-2-ylidene); Tipp = 2,4,6-iPr3C6H2; Ch = Se, Te) by treatment of NHC-stabilized aluminium dihydrides with elemental Se and Te is reported. The higher affinity of IMe4 in comparison with IiPr toward the Al center in [(NHC)Al(Tipp)-µ-Ch]2 can be used for ligand exchange. Additionally, the presence of excess IMe4 allows for cleavage of the dimers to form a rare example of a neutral multiply bonded heavier aluminium chalcogenide in the form of a tetracoordinate aluminium complex, (IMe4)2(Tipp)Al=Te. This species reacts with three equivalents of CO2 across two Al–CNHC and the Al=Te bond affording a pentacoordinate aluminium complex containing a dianionic tellurocarbonate ligand [CO2Te]2-, which is the first example of tellurium analogue of a carbonate [CO3]2-.