Palladium(II) Complexes of UnsymmetricalCNNPincer Ligands

Abstract

Unsymmetrical 1-(arylimino)-3-(2-hetarylimino)isoindolines have been prepared from 1,3-diiminoisoindoline, an arylamine (aniline, 2-methylaniline, 2-iodoaniline), and a heteroaromatic amine (2-amino-6-methylpyridine, 2-amino-4-methylthiazole) in a stepwise manner by two consecutive condensations. The metalation reactions of these compounds with palladium(II) acetate proceed upon cyclopalladation of the carbocyclic aryl moieties and yield unsymmetrical C, N, N pincer complexes in all cases. X-ray crystallographic analysis were performed on single crystals of hydrogen{acetato[1-phenylimino-3-(6-methylpyridylimino)isoindolinato]palladate(II)} H[(phpi)Pd(OAc)] and pyridine[1-(2-tolylimino)-3-(4-methylthiazolylimino)isoindolinato]palladium(II) [(2-tolti)Pd(py)] by which the coordination mode, the conformation, the protonation site, and the trans influence of the carbon donor were established. For one more C, N, N pincer complex, hydrogen{acetato[1-(2-iodophenylimino)-3-(6-methylpyridylimino)isoindolinato]palladate(II)} H[(2-Iphpi)Pd(OAc)], a similar mononuclear coordination mode was confirmed by (1)H NMR spectroscopy, whereas for the product of an oxidative addition reaction of a palladium(0) precursor to the iodoaryl derivative a product with exo coordination was found. First experiments showed the effectivity of one of these complexes as a precatalyst in CC coupling reactions (Heck and Stille coupling).

Isoindoline-derived ligands and applications

“…contains the characteristic data of the manganese complexes of BIIs. The numbers show a nearly perfect trigonal bipyramid (42) and an average, moderately distorted TBPY (38). Tau values are valid only for five coordinate structures.…”

“…Name., 2012, 00, [1][2][3] This journal is © The Royal Society of Chemistry 2012 subporphyrines are the cyclic formulations of DII but their synthesis requires different strategy from the previously mentioned molecules, furthermore their applications and research are both well documented. 42,43 Unsymmetry have been proved to be useful in the research of catecholase activity as well. Myrtene, α-pinene and carene have been used to build chiBIIs.…”

Derivati izoindolina, sinteza i biološka aktivnost. I. Prirodni i sintetski derivati izoindolina

“…Iz novije literature treba spomenuti radove Bröringa i sur. 35,36 Autori su opisali pripravu kompleksa paladija 74 s kiralnim bis(piridilimino)-derivatom izoindolina 73 (shema 17). Takvi ligandi omogućuju dizajniranje ciljanih trodimenzijskih struktura, što se može primijeniti u raznim područjima koordinacijske kemije.…”

Bis(4‐methylthiazolyl)isoindoline (4‐Mebti) Complexes of Palladium: Cationic [PdII(4‐Mebti)L]+Species with a L = Neutral Group XIV or Group XV Donor Ligand

“…Otherwise the N , N , N coordination of the chelate ligand is observed in short‐lived kinetic products. Within several minutes, and in particular in the presence of additional palladium acetate, these intermediates form thermodynamically stable products by rotation of one of the pyridine rings and C(sp 2 )–H activation 6. This process does not occur for α,ω‐Me 2 bti ligands (bti = bis(thiazolylimino)isoindoline7), which have so far been observed to form exclusively pseudoplanar structures with anionic and with neutral co‐ligands.…”