663151-73-3Relevant articles and documents
Formation of ruthenium-aminocarbene complexes from aldimines and aminals
Standfest-Hauser, Christina M.,Mereiter, Kurt,Schmid, Roland,Kirchner, Karl
, p. 1883 - 1892 (2003)
Specific pyridine-based aldimines and aminals act as chelating ligands towards the RuCpL and RuTpL (Tp = hydrido trispyrazolylborate) fragments giving κ2N,N′- coordinated cyclic imine complexes. Under particular conditions, as elucidated in this paper, these complexes rearrange into cyclic aminocarbene complexes. Thus, the reaction of [RuCp(L)(CH3CN)2] PF6 (L = CH3CN, PMe3, SbPh3) with 1 equiv. of py-N=CHR [R = Ph (phenyl), Fc (ferrocenyl), Np (naphthyl)] affords the cyclic aminocarbene complexes [RuCp(L)(=C(R)NH-py)]PF6, whereas when L = PPh3, PiPr3, and CO the reaction stops at the stage of the imine complex [RuCp(L) (κ2N,N′-py-N=CHR)]PF6. Analogously, [RuTp-(COD)Cl] (COD = 1,5-cyclooctadiene) also reacts readily with the imines py-N=CHR (R = Ph, pMeOC6H4, Np) at elevated temperatures to yield the aminocarbene complexes [RuTp{=C(R)NH-py}Cl]. This process may open a new synthetic route for obtaining carbene complexes. The mechanism of the imine-aminocarbene conversion was analyzed by DFT/B3LYP calculations. Accordingly, the operation of a direct 1,2 hydrogen shift can be ruled out; the reaction seems to involve hydrido iminoacyl intermediates resulting from C-H bond activation and deprotonation/protonation steps. Wiley-VCH Verlag GmbH & Co, KGaA, 69451 Weinheim, Germany, 2003.
