{'fraction_non_alphanumeric': 0.03913630229419703, 'fraction_numerical': 0.005398110661268556, 'mean_word_length': 5.684684684684685, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Synthesis, structure and insertion reactivity of Lewis acidic 9-aluminafluorenes.

9-Aluminafluorenes have only been sparingly investigated and their properties still remain largely unexplored. Herein, we report the synthesis of five aluminafluorene derivatives with a diverse array of aluminium substituents and probe their Lewis acid properties and reactivity. We show that 9-bromo-9-aluminafluorene readily forms Lewis acid-base adducts with N-heterocyclic carbenes (NHCs), cyclic (alkyl)(amino)carbenes (CAACs) and pyridines and that it undergoes a selective ring expansion reaction with the iminoborane tBuN[triple bond, length as m-dash]BMes to give a seven-membered ring, which can be viewed as a boron-nitrogen analogue of alumepins.