Synthesis of palladium complexes derived from amido linked N-heterocyclic carbenes and their use in Suzuki cross coupling reactions

One of the authors (RSC) is grateful to DST for the financial support under the DST young scientist scheme YSS/2014/000797.Treatment of 1-(n-butyl)-3-N-(2-Ar)acetamido-1, 3-imidazolium chloride (Ar=furylmethyl,phenylmethyl) with excess K2CO3 and [PdCl2(L−L)] (L−L=2 PPh3, dppf) afforded orange compounds of composition [(1-(n-butyl)-3-N-(2-Ar)acetamido-1,3-imidazol-2-ylidene)]2Pd (Ar=furylmethyl; phenylmethyl). These complexes were characterized by NMR (1H and 13C{1H} NMR), IR and micro-analysis data. Subsequently, the catalytic efficiency of these complexes for cross coupling reactions between 4-haloarenens (halo=Br, I) and phenylboronic acid was studied under different solvents (acetonitrile, THF and DMF), temperatures with different catalyst loadings. The molecular structure of [(1-(n-butyl)-3-N-(2-furylmethyl)acetamido-1, 3-imidazol-2-ylidene)]2Pd was established by single crystal X-ray diffraction analysis.PostprintPeer reviewe

Coordination, Agostic Stabilization, and C−H Bond Activation of N-Alkyl Heterocyclic Carbenes by Coordinatively Unsaturated Ruthenium Hydride Chloride Complexes

11 páginas, 8 figuras, 1 tabla, 6 esquemas.The products formed upon reaction of Ru(PPh3)3HCl and [Ru(PiPr3)2HCl]2 with the N-heterocyclic carbenes 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (IiPr2Me2, 1) and 1,3-diethyl-4,5-dimethylimidazol-2-ylidene (IEt2Me2, 2) proved to be dependent on the phosphine and the N-substituent of the carbene. Thus, Ru(PPh3)3HCl reacts with both 1 and 2 at room temperature in CH2Cl2 to give a mixture of products consisting of cis-/trans-PPh3 isomers of the agostic complexes Ru(NHC)(PPh3)2HCl (NHC = IiPr2Me2, 3a/3b; IEt2Me2, 8a/8b), the anagostic species Ru(NHC)(PPh3)2HCl (NHC = IiPr2Me2, 4; IEt2Me2, 9), and in the case of IiPr2Me2 the C−H activated complex Ru(IiPr2Me2)′(PPh3)2Cl (5). Addition of 1 atm of C2H4 to the mixture of 3a/3b, 4, and 5 leads to complete conversion to 5. [Ru(PiPr3)2HCl]2 reacts with both 1 and 2 to yield only the anagostic complexes Ru(NHC)(PiPr3)2HCl (NHC = IiPr2Me2, 6; IEt2Me2, 10), which on the basis of NMR evidence react with C2H4 to give the doubly C−H activated alkenyl-NHC complexes Ru{η2-C(NiPr)CMeCMeN(CMe═CH)}(PiPr3)2Cl (7) and Ru{η2-C(NEt)CMeCMeN(CH═CH)}(PiPr3)2Cl (11). Addition of 1 to Ru(PiPr3)2(CO)HCl affords the agostic stabilized monocarbene complex Ru(IiPr2Me2)(PiPr3)(CO)HCl (12) and the tris-carbene species Ru(IiPr2Me2)3(CO)HCl (13). Complexes 3a, 4, 5, 6, 8a, 10, 12, and 13 have been structurally characterized.We thank the EPSRC (S.B.) and Spanish Ministerio de Ciencia e Innovación (E.M.M.) for financial support.Peer reviewe

Mercury complexes of an N-heterocyclic carbene derived from a calixarene/azolium cyclophane hybrid

© Springer Science+Business Media Dordrecht 2015.Reaction of mercuric acetate with an imidazolium-linked cyclophane incorporating 2,6-phenolic moieties results in formation of an interesting new N-heterocyclic carbene (NHC) complex of mercury. The new complex is cationic and binuclear, incorporating two mercury centres and two bis(NHC) ligands, each mercury atom being bound by two NHC moieties and two phenol/phenoxy moieties. Forms of the complex having coordinating ((Formula presented.))and non-coordinating ((Formula presented.))counterions have been structurally characterised