Sequential Formation of [Ru(IPr)2(CO)H(OH2)]+ and [Ru(IPr)(η6-C6H6)(CO)H]+ upon Protonation of Ru(IPr)2(CO)H(OH) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene)

Protonation of the N-heterocyclic carbene (NHC) complex Ru(IPr)2(CO)H(OH) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) with HBF4·OEt2 in thf affords the cationic aqua hydride complex [Ru(IPr)2(CO)H(OH2)](BF4), whereas if the solvent is changed to benzene, loss of imidazolium salt and H2O occurs to leave the 12e fragment [Ru(IPr)(CO)H] + , which is isolated as the cationic arene species [Ru(IPr)(η6-C6H6)(CO)H](BF4).