A bromo-capped diruthenium(i,i) N-heterocyclic carbene compound for in situ bromine generation with NBS: catalytic olefin aziridination reactionsDedicated to Professor Kim R. Dunbar on the occasion of her 60th birthday.Electronic supplementary information (ESI) available: Experimental details, supporting figures, spectroscopic and crystallographic data. CCDC 1841806. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8dt01851k

A bromo-capped metal-metal bonded diruthenium( i , i ) complex Ru 2 (CO) 4 (PIN) 2 Br 2 ( 1 ) (PIN = 1-isopropyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazol-2-ylidene) generates bromine with N -bromosuccinimide (NBS) at room temperature. Cycloalkene and stilbene are readily brominated by stoichiometric reactions with 1 and NBS. An analysis of the dibrominated products suggests the formation of cyclic bromonium intermediates indicating in situ Br 2 generation. Complex 2 , an iodide analogue of 1 , is also synthesized. The reaction of 2 with N -iodosuccinimide releases I 2 , which is confirmed by the starch-iodine test. The catalytic utility of 1 is examined for the bromination of phenol. Catalyst 1 , in combination with NBS and base, exhibits regioselectivity towards monobrominated products. Furthermore, efficient olefin aziridination is demonstrated utilizing catalyst 1 in the presence of NBS, K 2 CO 3 and TsNH 2 . A bromo-capped diruthenium( i , i ) complex activates NBS to produce bromine in situ , and thus catalyses bromine-mediated olefin aziridination reactions.