Ruthenium complexes azido

Iridium dimer complexes catalyse the 3 + 2-cycloaddition reactions of organic azides with bromoalkynes to furnish 1,5-disubstituted 4-bromo-1,2,3-triazoles in excellent yields under mild conditions. Ruthenium(II)-azido complexes undergo 3 + 2-cycloaddition reactions with strained cyclooctynes under ambient temperatures. No reaction was observed with non-activated terminal or internal alkynes under the same conditions. Dithioic acid copper catalysts (60) catalyse the 3 + 2-cycloaddition reaction of azides with alkynes to form 1,4-disubstituted-1,2,3-triazoles in various solvents and under various temperatures. Thermal Huisgen 3 + 2-cycloaddition reactions of azides and bis(trimethylsilyl)acetylene formed 4,5-bis(trimethylsilyl)-l/f-l,2,3-triazoles in low to high yields (15-95%). The Cu(I)-catalysed 3 + 2-cycloaddition... 

In a similar way, ruthenium(II) - azido complex reacts toward electron-deficient and strain-activated alkynes at room temperature. Nonactivated terminal and internal alkynes failed to react under such conditions [33]. 

Ruthenium forms several mixed azido complexes and one all-azido complex. The crystalline solids and their solutions are light sensitive. The tetraethyl-ammonium salt, [(C2Hs)4N]3 [Ru (N3)e], is made by adding 0.2 g K2 [Ru Cle] to a 40°C solution of 13 g sodium azide in 40 ml water and 20 ml ethanol. Ru(IV) is reduced to Ru(III) and nitrogen evolves. When the color changes from orange to red and the gas evolution ceases, an aqueous solution of 4 g tetraethylam-monium bromide is added and the solution is concentrated to yield brick-red crystals of the above complex salt [162]. 

Wag T-H, Wu F-L, Chiang G-R, He S-T, Lo YH. Preparation of ruthenium azido complex containing a Tp Hgand and ruthenium-catalyzed cycloaddition of organic... 

Chen C-K, Tong H-C, Chen Hsu C-Y, et al. Synthesis and reactivity of ruthenium azido complexes containing a hydridotris(pyrazolyl)borate ligand and dimerization of terminal alkynes in organic and aqueous media. Organometallics. 2009 28 3358-3368. 

Photochemical reactions of the iridium(m) and rhodium(m) complexes [M(NH3)6(N3)] + result in the production of a co-ordinated nitrene intermediate. In concentrated hydrochloric add the iridium(m) product is [Ir(NH3)6(NH2Cl)] +, as in the equivalent thermal reaction. These iridium(ra) and rhodium(m) complexes thus behave photochemically in a similar mmmer to hydrazoic acid and to organic azides. Their behaviour contrasts with that of some other transition-metal azide complexes, e.g. those of ruthenium(n), where an azido-radical is the photochemical intermediate. One can indeed group transition-metal azide complexes into three groups, with their thermal and photochemical reactions depending on the relative ease of oxidation or reduction (or neither) of the transition-metal centre. ... 

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