885666-35-3Relevant academic research and scientific papers
Achiral and chiral transition metal complexes with modularly designed tridentate PNP pincer-type ligands based on N-heterocyclic diamines
Benito-Garagorri, David,Becker, Eva,Wiedermann, Julia,Lackner, Wolfgang,Pollak, Martin,Mereiter, Kurt,Kisala, Joanna,Kirchner, Karl
, p. 1900 - 1913 (2006)
The synthesis and characterization of a series of molybdenum, iron, ruthenium, nickel, palladium, and platinum complexes containing new achiral and chiral PNP pincer-type ligands based on the N-heterocyclic diamines 2,6-diaminopyridine, N,N′-di-10-undecenyl-2,6-diaminopyridine, N,N′-dihexyl-2,6-diaminopyridine, and 2,6-diamino-4-phenyl-1,3,5-triazine are reported. The new PNP ligands are prepared conveniently in high yield by treatment of the respective N-heterocyclic diamines with 2 equiv of a variety of achiral and chiral R2PCl compounds in the presence of base. Molybdenum PNP complexes of the type [Mo(PNP)(CO)3PNP] are obtained by treatment of [Mo(CO)3(CH3CN)3] with 1 equiv of the respective PNP ligand. They were found to react with I2 to give novel seven-coordinate pincer complexes of the types [Mo(PNP)(CO) 3I]+ and [Mo(PNP)(CO)2(CH3CN)I] + depending of whether the reaction is carried out in CH 2Cl2 or CH3CN. With [Fe(H2O) 6](BF4)2 and 1 equiv of PNP ligand in acetonitrile dicationic complexes of the type [Fe(PNP)(CH3CN) 3](BF4)2 are obtained. The cis and trans dichloride complexes [Ru(PNP)(PPh3)Cl2] are prepared by a ligand exchange reaction of [RuCl2(PPh3)3] with a stoichiometric amount of the respective PNP ligand. Cationic PNP complexes of Ni(II), [Ni(PNP)Br]Br, were synthesized by the reaction of [NiBr2(DME)] with 1 equiv of PNP ligand. In similar fashion, treatment of [M(COD)X2] (M = Pd, Pt; X = C1, Br) with 1 equiv of PNP ligand yields the cationic square-planar complexes [M(PNP)X]X. If the reaction is carried out in the presence of the halide scavenger KCF3SO 3, complexes of the type [M(PNP)X]CF3SO3 are obtained, which are better soluble in nonpolar solvents than the analogous halide compounds. X-ray structures of representative Mo, Fe, Ru, Ni, and Pd PNP complexes have been determined. Finally, the use of the palladium complexes as catalysts for the Suzuki - Miyaura coupling of some aryl bromides and phenyl boronic acid has been examined.
