Rubidium and caesium aluminyls: synthesis, structures and reactivity in C-H bond activation of benzene

Expanding knowledge of low valent aluminium chemistry, rubidium and caesium aluminyls are reported to complete the group 1 (Li-Cs) set of metal aluminyls. Both compounds crystallize as a contacted dimeric pair supported by MMIDLINE HORIZONTAL ELLIPSIS pi(arene) interactions with a pronounced twist between aluminyl units. Density functional theory calculations show symmetrical bonding between the M and Al atoms, with an Al centred lone-pair donating into vacant Rb and Cs orbitals. Interestingly, despite their structural similarity the Cs aluminyl enables C-H bond activation of benzene, but not the Rb aluminyl reflecting the importance of the alkali metal in these heterobimetallic systems.

Automated summary

This study reports the rubidium and caesium aluminyls, completing the set of metal aluminyls in group 1 (Li-Cs) and expanding knowledge of low valent aluminium chemistry. The compounds form contacted dimeric pairs supported by pi(arene) interactions and exhibit a pronounced twist between aluminyl units. Interestingly, the Cs aluminyl enables C-H bond activation of benzene, while the Rb aluminyl does not, highlighting the significance of alkali metal in these heterobimetallic systems.