Synthesis and Reactivity of Ruthenium Azido Complexes Containing a Hydridotris(pyrazolyl)borate Ligand and Dimerization of Terminal Alkynes in Organic and Aqueous Media

Abstract

Facile ligand substitution is observed when the ruthenium azido complex (PPh 3 )[Ru]-N 3 (1; [Ru] ) Tp(PPh 3 )Ru) is treated with CH 3 CN, yielding the nitrile-substituted ruthenium azido complex (CH 3 CN)[Ru]-N 3 (2). Alkylation, [3 + 2] cycloaddition, and catalytic reactions of complex 2 have been investigated. In the case of [3 + 2] cycloaddition reactions, the metal-bound heterocyclic complexes (CH 3 CN)[Ru]-N 3 C 2 (CO 2 Me) 2 (3a), (CH 3 CN)[Ru]-N 3 C 2 HCO 2 Me (5), and (CH 3 CN)[Ru]-N 3 C 2 HCN (6) are obtained from dimethyl acetylenedicarboxylate, methyl propiolate, and fumaronitrile, respectively. The tetrazolato complex 8) is prepared from 2 and TCNE. Alkylation of 3a with organic bromides affords N-alkylated five-membered-ring organic triazoles. The reaction of CS 2 with 2 produces the thermally unstable thiothiatriazolate (CH 3 CN)[Ru]-N 3 CS(S) (10), which decomposes to the isothiocyanate (CH 3 CN)[Ru]-NCS (11). On the other hand, several cationic imine complexes {(CH 3 CN)[Ru]-(NHdCHR)} + (12a, R ) H; 12b, R ) CH 3 ; 12c, R ) HCdCH 2 ) are formed by the reaction of RCH 2 X with the negatively charged nitrogen atom of the azido ligand on Ru II . The reaction proceeds via formation of an alkylimido intermediate followed by N 2 evolution and proton transfer from the alkyl group to the imido nitrogen atom. Preliminary results on the catalytic activity of 2 are also presented. Interestingly, complex 2 catalyzes the dimerization of some terminal alkynes HCtCR in organic and aqueous medium. Whereas with R ) Ph, SiMe 3 , t-Bu isomeric mixtures of head-to-head and head-to-tail coupling products are obtained, in the case of R ) COOMe, E-selective head-to-head dimerization takes place exclusively. The structures of 1, 8, and 12c have been determined by X-ray diffraction analysis.

One-pot Synthesis of Octyne-Ruthenium on Carbon Nanoparticles

“…Recently, many reports have been generally successfully prepared alkyl vinylidene -linkage to ruthenium core using the special coordinating ligand for example terminal alkyne [1][2][3][4][5] or some vinyl aromatic [6][7]. It is confirmed that alkyne fragments around the metal core do not only functions as protecting ligands promoting the stability of the nanoparticles but also enhances some optical and fluorescence characteristic via the pi-bond interaction between methylene and metal core [8].…”

“…Octyne-ruthenium was deposited on CPNs by mixing RuCl 3 , NaBH 4 , and CNPs at the ratio of 3:3:10 in pure water. Briefly describe, 10 mg of CNPs was mixed with 1 mg RuCl 3 in 10 mL of water and stir over night.…”

Methyl 1-benzyl-1H-1,2,3-triazole-4-carboxylate

“…Catalytic transformations of organic alkynes mediated by ruthenium complexes are well known, and confirmation for the intermediacy of ruthenium(II) acetylide and vinylidene complexes has been provided (Bruneau & Dixneuf, 1999;Cheng et al, 2009;Naota et al, 1998;Trost et al, 2001). Therefore, ruthenium was a logical choice in our search for a new catalyst of click reaction (Chen et al, 2009). Organic azides are synthetically useful reagents.…”

“…For catalytic transformations of organic alkynes mediated by ruthenium complexes, see: Naota et al (1998); Bruneau & Dixneuf (1999); Trost et al (2001); Chen et al (2009); Cheng et al (2009). For the synthesis of triazoles, see: Padwa (1976).…”

Preparation of ruthenium azido complex containing a Tp ligand and ruthenium-catalyzed cycloaddition of organic azides with alkynes in organic and aqueous media: Experimental and computational studies

“…On the other hand, we have reported the first example that dimerization of alkynes with the ruthenium azido complex instead of ruthenium chloride complex to give (E)-enynes carried out in organic and aqueous media [15]. Therefore, ruthenium azido complex was a logical choice in our search for a new catalyst of click reaction.…”