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.