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.

On the Critical Effect of the Metal (Mo vs. W) on the [3+2] Cycloaddition Reaction of M3S4 Clusters with Alkynes: Insights from Experiment and Theory

“…[12] Thes olventa ppearst op layam inor role, as changes are of less than an order of magnitude.F or phenylacetylene and its derivatives, the rate increases with the number of electron-withdrawing substituents on the phenyl group buta gain it is as mall increase, the rates for F PhA and CF 3 PhAbeing only larger than for the unsubstituteda lkyne by af actor of two or three, respectively.T he rates of the cycloaddition with btd and PrA only differ by af actor of two, thus showingt hat the rate of the reaction is not very different for related internal and terminal alkynes. It is also interesting to note that for some of the alkynes the kinetics of the cycloaddition reaction with cluster[ 1]…”

Au-iClick mirrors the mechanism of copper catalyzed azide–alkyne cycloaddition (CuAAC)

“…[2][3][4] Others [5][6][7] extended iClick to include the already prevalent [8][9] cycloaddition of an organic substrate to either a metal-azide or metal-acetylide. 7,[10][11][12][13][14][15][16][17][18][19][20][21] Important to this work, Gray et al 22 demonstrated that gold-acetylides and gold-azides will undergo cycloaddition to their organic counterparts. Despite the fact that several transition metals other than Cu(I) catalyze the azide-alkyne cycloaddition, including ruthenium, silver, and iridium, [23][24][25][26] it became apparent that not all metal-acetylide/azide species will participate in the iClick cycloaddition.…”

Organogold oligomers: exploiting iClick and aurophilic cluster formation to prepare solution stable Au4 repeating units

“…6 Critical in the pursuit of building complexity is the precise control of bond forming events and is particularly exemplified by the Cu I catalyzed azide-alkyne cycloaddition reaction (CuAAC). Others [11][12][13] have broadened the iClick concept to include the cycloaddition of organic substrates to either a metal-azide or metal-acetylide (M; Scheme 1), which are already rather prevalent reactions, [13][14][15][16][17][18][19][20][21][22][23][24][25] and the subject of reviews. The metal-azide/metal-acetylide cycloaddition (M-M′) was given the term inorganic click (iClick) as a distinguishing feature that calls attention to chemistry occurring within the coordination sphere of a metal ion.…”