138332-70-4Relevant articles and documents
Mono- and dinucleating Ni(II), Cu(II), Zn(II) and Fe(III) complexes of symmetric and unsymmetric Schiff bases incorporating salicylimine functions - Synthetic and structural studies
Meng, Qinghua,Clegg, Jack K.,Brock, Aidan J.,Jolliffe, Katrina A.,Lindoy, Leonard F.,Wei, Gang
, p. 113 - 121 (2014)
The known Schiff base, 3-(2-aminophenylamino)-1-phenylbut-2-en-1-one (1), formed by 1:1 condensation of o-phenylenediamine and benzoylacetylacetone reacts at its free amine site with salicylaldehyde and 5-tert-butylsalicylaldehyde in the presence of Ni(II) and Cu(II) acetates, or with 5-tert-butylsalicylaldehyde in the presence of Zn(II) acetate, to generate 1:1 (M:L) diimine complexes (2) of the corresponding doubly deprotonated, unsymmetric, O2N 2-tetradentate ligands. In contrast, reaction of Zn(II) acetate with 1 and salicylaldehyde led to Schiff base exchange (with loss of benzoylacetylacetone) to yield symmetric [ZnL3] [where L3 is N,N′-o-phenylenebis(salicyliminato)]. Similarly, when Fe(II) chloride was substituted for metal acetate in the reaction of 1 with 5-tert-butyl- salicylaldehyde and the initial product crystallised in the presence of dabco (as base), a related Schiff base exchange reaction occurred along with aerial oxidation of the Fe(II) to produce the neutral dinuclear [Fe III(L4)2(μ-O)] species [where L4 is N,N′-o-phenylenebis(5-tert-butylsalicyliminato)] in which Fe(III) centres are linked by an oxo group to produce two 5-coordinate Fe(III) centres; pairs of these (oxo-bridged) dinuclear complex units are further linked via elongated intermolecular Fe-Ophenolic contacts (Fe-O, 2.44 A?) to form an unusual tetranuclear supramolecular cluster. This complex was also synthesised directly by the in situ reaction of 5-tert-butyl-salicylaldehyde, o-phenylenediamine and Fe(II) chloride (2:1:1 mol ratio) in air. In an extension of these studies, the in situ reaction of the 1,3-aryl linked bis-β-diketone, 1,1-(1,3-phenylene)-bis-butane-1,3-dione), o-phenylenediamine, salicylaldehyde and Ni(II) acetate in a 1:2:2:2 ratio yielded [Ni2L5], the dinuclear analogue of the unsymmetric mononuclear Ni(II) complex 2, in which each nickel centre has a square planar environment. Reaction of the above 1,3-phenylene linked bis-β-diketone precursor with o-phenylenediamine in a 1:2 M ratio yields 1,3-bis(4-methyl-3H- benzo[b][1,4]diazepin-2-yl)benzene as its monohydrate (3·H2O) incorporating two 7-membered diaza heterocyclic rings; thus contrasting with the 'open' Schiff base structure observed for 1. X-ray structures of 1, 3·H2O, [NiL1]·py, [NiL1] ·EtOH, [NiL2], [CuL1]·py, [CuL 1]·0.5CHCl3, [(FeL4)2(μ-O) ]2·1.5THF·0.4EtOH·0.6H2O and [NiL5]·0.25EtOH·0.125py are reported.
