title: Azide alkyne cycloaddition facilitated by hexanuclear rhenium chalcogenide cluster complexes.
abstract: Two hexanuclear rhenium clusters containing azide ligands, [Re6Se8(PEt3)5(N3)]BF4 and [Re6Se8(PEt3)4(N3)2], were synthesized from the analogous pyridine complexes and fully characterized. Studies show that [Re6Se8(PEt3)5(N3)]BF4 reacts with activated alkynes, dimethyl acetylenedicarboxylate and methyl 4-hydroxyhex-2-yneoate, to form the triazolate cluster complexes [Re6Se8(PEt3)5(L1 or L2)]BF4 (where L1 = 4,5-bis(methoxycarbonyl)-1,2,3-triazol-2-yl and L2 = 4-methoxycarbonyl-5-(1-propanol)-1,2,3-triazol-2-yl). The bis-triazolato complex, cis-[Re6Se8(PEt3)4(L1)2] was also prepared via a similar reaction starting with cis-[Re6Se8(PEt3)4(N3)2] demonstrating that these clusters can promote two azide moieties to undergo heterocyclic ring formation. The structures of [Re6Se8(PEt3)5(N3)]BF4, [Re6Se8(PEt3)4(N3)2], and [Re6Se8(PEt3)5(L1)](BF4), were determined by single-crystal X-ray diffraction analysis. In addition, studies involving the alkylation of [Re6Se8(PEt3)5(L1)]BF4 with benzyl bromide and methyl iodide are reported.
authors.affiliation: Department of Chemistry, Illinois State University, Normal, IL 61790-4160, USA.
authors.forename: Stanley A
authors.initials: SA
authors.lastname: Knott
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Templeton
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Durham
authors.forename: Angela M
authors.initials: AM
authors.lastname: Howard
authors.forename: Robert
authors.initials: R
authors.lastname: McDonald
authors.forename: Lisa F
authors.initials: LF
authors.lastname: Szczepura