Inorganic Chemistry Frontiers: home for cutting-edge research

Abstract

Welcome to the first issue of Inorganic Chemistry Frontiers 2015

gem-Dimethyl-substituted bis(imino)dihydroquinolines as thermally stable supports for highly active cobalt catalysts that produce linear PE waxes

“…This can explained by the steric hindrance of the ortho substituents affecting the rate of the ethylene coordination by hindering its approach to the metal center. 19,30,33,35 Surprisingly however, the most bulky Co6 showed a higher activity than the ethyland isopropyl-containing Co2 and Co3. It is unclear as to this difference but may be due to the presence of the para-t-butyl group that can not only impart a greater positive inductive effect but can also improve the solubility of the precatalyst.…”

“…Inspection of their GPC curves indicates that the value of Mw steadily declines as the temperature is raised reaching its lowest value at 90 °C ( Figure 3; see Figures S1 -S7), an observation that can be ascribed to either increased chain transfer to aluminum or chain termination by β-H elimination at the higher temperatures. 14,19,[28][29][30][31][32][33][34] Meanwhile, the molecular weight distribution remained relatively narrow (Mw/Mn range: 2.3 − 2.7) over the temperature range consistent with an active species displaying single-site characteristics. Table 2).…”

“…Strong absorption bands around 1610 cm −1 are a feature of the IR spectra of Co1 − Co6 which are typical of bound imine nitrogen atoms and indeed around 30 cm -1 less than that observed in the free ligands. 14,19,[28][29][30][31][32][33] Further support for the composition of complexes is provided by their microanalytical data.…”

“…Indeed, numerous structural variations to the prototypical bis(arylimino)pyridine-metal precatalysts (A, Chart 1) have been performed including to the substituents belonging to the N-aryl groups and to the imino-carbon atoms. [18][19][20][21][22][23][24][25][26][27] As a further variable introduced by our group and others is the degree of ring strain present in the bis(imino)pyridine framework. Indeed by fusing one or two carbocyclic rings to the central pyridine unit, a wide variety of complexes have now been reported including those based on 1,8-diimino-2,3,4,5,6,7-hexahydroacridines (B, Chart 1), 28 2-(1-(arylimino)ethyl)-8-arylimino-5,6,7-trihydroquinolines (C), [29][30][31] 2-(1-(arylimino)ethyl)-7-arylimino-6,6-dimethyl cyclopentapyridines (D, Chart 1) 32 and 2-(1-arylimino)ethyl-9arylimino-5,6,7,8-tetrahydro-cycloheptapyridines (E).…”

Exceptionally high molecular weight linear polyethylene by using N,N,N′‐Co catalysts appended with a N′‐2,6‐bis{di(4‐fluorophenyl)methyl}‐4‐nitrophenyl group

“…[1][2][3] Following this ground breaking work, many synthetic efforts have been dedicated to exploring the full potential of these catalysts which have, [4][5][6][7][8][9][10][11][12][13][14][15] in large part, been concerned with modifications to the substituents belonging to bis(arylimino) pyridine or related ligand frameworks. [16][17][18][19][20][21][22][23][24][25] Of particular note have been the raft of steric and electronic variations made to the ortho-and para-positions of the N-aryl groups of the tridentate ligand. [25] Elsewhere, ligand development has seen the emergence of bis(imino)pyridines fused with carbocycles that can be varied in terms of their ring size (B, n = 0-3, Scheme 1).…”