Substituted N-picolylethylenediamines of the type (ArNHCH2CH2){(2-C5H4N)CH2}NR [R = Me, 4-CH2CH(C6H4)CH2, (2-C5H4N)CH2] and their transition metal(ii) halide complexes

Abstract

Alkylation of (ArNHCH2CH2){(2-C5H4N)CH2}NH with RX [RX = MeI, 4-CH2=CH(C6H4)CH2Cl) and (2-C5H5N)CH2Cl] in the presence of base has allowed access to the sterically demanding multidentate nitrogen donor ligands, {(2,4,6-Me3C6H2)NHCH2CH2}{(2-C5H4N)CH2}NMe (L1), {(2,6-Me3C6H3)NHCH2CH2}{(2-C5H4N)CH2}NCH2(C6H4)-4-CH=CH2 (L2) and (ArNHCH2CH2){(2-C5H4N)CH2}2N (Ar = 2,4-Me2C6H3 L3a, 2,6-Me2C6H3 L3b) in moderate yield. L3 can also be prepared in higher yield by the reaction of (NH2CH2CH2){(2-C5H4N)CH2}2N with the corresponding aryl bromide in the presence of base and a palladium(0) catalyst. Treatment of L1 or L2 with MCl2 [MCl2 = CoCl2.6H2O or FeCl2(THF)1.5] in THF affords the high spin complexes [(L1)MCl2](M = Co 1a, Fe 1b) and [(L2)MCl2](M = Co 2a, Fe 2b) in good yield, respectively; the molecular structure of reveals a five-coordinate metal centre with bound in a facial fashion. The six-coordinate complexes, [(L3a)MCl2](M = Co 3a, Fe 3b, Mn 3c) are accessible on treatment of tripodal L3a with MCl2. In contrast, the reaction with the more sterically encumbered leads to the pseudo-five-coordinate species [(L3b)MCl2](M = Co 4a, Fe 4b) and, in the case of manganese, dimeric [(L3b)MnCl(mu-Cl)]2 (4c); in 4a and 4b the aryl-substituted amine arm forms a partial interaction with the metal centre while in 4c the arm is pendant. The single crystal X-ray structures of , 1a, 3b.MeCN, 3c.MeCN, 4b.MeCN and 4c are described as are the solution state properties of 3b and 4b.

Iron(III) Complexes with the Ligand N′,N′‐Bis[(2‐pyridyl)methyl]ethylenediamine (uns‐penp) and Its Amide Derivative N‐Acetyl‐N′,N′‐bis[(2‐pyridyl)methyl]ethylenediamine (acetyl‐uns‐penp)

“…[12,13,[15][16][17][18][19] However, most of the authors unfortunately do not refer to the original synthesis of this ligand by Mandel and co-workers [12] and in one case it is presented a second time and described incorrectly as a new compound (ten years later in the same journal). [14] Some of us have used this ligand previously in studies within the field of copper chemistry and have improved its preparation.…”

“…[14] Furthermore, very recently an iron() complex of a derivative of uns-penp was described. [15] However, so far no iron() complexes have been described in the literature. Therefore, we decided to study the appropriate iron() complexes of this ligand as well as of its acetyl derivative N-acetyl-NЈ,NЈ-bis [(2-pyridyl)methyl]ethylenediamine (acetyl-uns-penp; Scheme 1), an amide that was obtained during the synthesis of uns-penp.…”

Ethylene oligomerization using iron complexes: beyond the discovery of bis(imino)pyridine ligands

“…Upon activation with MAO in a high ratio (Al/Fe = 400), these iron precursors oligomerized ethylene with poor activities (o10 3 g (mol h atm) À1 under 1 atm and at 25 1C). 55,56 Neutral bidentate ligands…”

“…The same behaviour was observed with ligands 53 developed by Kempe et al 62 New bidentate bis(imino)cyclodisphophazane ligands 54 led to inactive systems when associated with an iron centre. 63 Sun and co-workers have developed a range of bidentate ligands based on quinoxaline 55 64 and quinoline ligands (56)(57)(58). [65][66][67] The iron complex containing 2-(2-pyridyl)quinoxaline ligands gave only marginal activity.…”

Iron and Cobalt Complexes of 2,3,7,8-Tetrahydroacridine-4,5(1H,6H)-diimine Sterically Modulated by Substituted Aryl Rings for the Selective Oligomerization to Polymerization of Ethylene

“…Bisimines derived from hydrazines or 1-amino pyrroles instead of anilines were also found to be efficient in ethylene activation . Apart from the works on derivatizations of 2,6-bis(imino)pyridyl metal complexes, there have been a lot of reports based on alternative models of catalysts for ethylene reactivity through designing novel organic compounds as ligands with tridentate N ∧ N ∧ N coordination features such as 2-imino-1,10-phenanthrolines, 2-(benzimidazol-2-yl)-1,10-phenanthrolines, 2-oxazoline-1,10-phenanthrolines, 2-quinoxalinyl-6-iminopyridines, 2-(benzimidazolyl)-6-iminopyridines, N -((pyridin-2-yl)methylene)quinolin-8-amine, 2-methyl-2,4-bis(6-iminopyridin-2-yl)-1 H -1,5-benzodiazepines, N -picolylethylenediamines, 6-(organyl)-2-(imino)pyridines, 2-(1 H -2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines, and 2,8-bis(1-aryliminoethyl)quinolines . In general, Fe and Co complexes not only show high catalytic activities but also produce oligomers and polyethylenes (PEs) of high linearity with terminal vinyl groups …”