Coordinatively unsaturated ruthenium complexes as efficient alkyneazide cycloaddition catalysts

The performance of 16-electron ruthenium complexes with the general formula Cp*Ru(L)X (in which L = phosphine or N-heterocyclic carbene ligand; X = Cl or OCH2CF3) was explored in azidealkyne cycloaddition reactions that afford the 1,2,3- triazole products. The scope of the Cp*Ru(PiPr 3)Cl precatalyst was investigated for terminal alkynes leading to new 1,5-disubstituted 1,2,3-triazoles in high yields. Mechanistic studies were conducted and revealed a number of proposed intermediates. Cp*Ru- (PiPr3)(2-HCCPh)Cl was observed and characterized by 1H, 13C, and 31P NMR at temperatures between 273 and 213 K. A rare example of N,N-κ2-phosphazide complex, Cp*Ru(κ2- iPr3PN3Bn)Cl, was fully characterized, and a single-crystal X-ray diffraction structure was obtained. DFT calculations describe a complete map of the catalytic reactivity with phenylacetylene and/or benzylazide. © 2012 American Chemical Society.

Sponsors

S.P.N. would like to thank the ERC (Advanced Researcher Award FUNCAT) for financial support. A.P. thanks the Spanish MICINN for a Ramon y Cajal contract (ref RYC-2009-05226) and the European Commission for a Career Integration Grant (CIG09-GA-2011-293900). L.C. and A.P. thank the HPC team of Enea (www.enea.it) for using the ENEA-GRID and the HPC facilities CRESCO (www.cresco.enea.it) in Portici, Italy. M.L. acknowledges Salerno Province and the University of Salerno for supporting her stay at the University of St Andrews (International Mobility Scholarship 2009). S.P.N. is a Royal Society Wolfson Research Merit Award holder.

Publisher

American Chemical Society (ACS)

Journal

Organometallics

ISSN

02767333

DOI

10.1021/om2012425

Collections

Articles; Physical Sciences and Engineering (PSE) Division; Chemical Science Program; KAUST Catalysis Center (KCC)