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

Abstract

The reactions of C(6)H(5)CH(CH(3))N(3) with nitrile solvates of the [Re(6)(mu(3)-Se)(8)](2+) core-containing cluster, [Re(6)(mu(3)-Se)(8)(PEt(3))(5)(MeCN)](2+)(1) and cis-[Re(6)(mu(3)-Se)(8)(PEt(3))(4)(MeCN)(2)](2+) (2), afforded the corresponding cationic imino complexes [Re(6)(mu(3)-Se)(8)(PEt(3))(5)(PhN horizontal lineCHCH(3))](2+) (3) and cis-[Re(6)(mu(3)-Se)(8)(PEt(3))(4)(PhN horizontal lineCHCH(3))(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 alpha-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.