Cluster-Bound Nitriles Do Not Click with Organic Azides: Unexpected Formation of Imino Complexes of the [Re₆(μ₃-Se)₈]²⁺ Core-Containing Clusters

The reactions of C₆H₅CH(CH₃)N₃ with nitrile solvates of the [Re₆(μ₃-Se)₈]²⁺ core-containing cluster, [Re₆(μ₃-Se)₈(PEt₃)₅(MeCN)]²⁺(1) and cis-[Re₆(μ₃-Se)₈(PEt₃)₄(MeCN)₂]²⁺ (2), afforded the corresponding cationic imino complexes [Re₆(μ₃-Se)₈(PEt₃)₅(PhNCHCH₃)]²⁺ (3) and cis-[Re₆(μ₃-Se)₈(PEt₃)₄(PhNCHCH₃)₂]²⁺ (4), respectively. Both compounds were spectroscopically and crystallographically characterized. A mechanism involving a 1,2-shift of one of the groups on the azido α-C atom of the cluster−azide intermediate concerted with the photoexpulsion of dinitrogen of the azido ligand is invoked to rationalize the formation of the imino complexes. Density functional theory calculations showed that a cluster-to-ligand transition was responsible for the absorption that promotes the photodecomposition of the cluster−azide complex.