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dc.contributor.authorKitos, Alexandros A.en
dc.contributor.authorEfthymiou, Constantinos G.en
dc.contributor.authorManos, Manolis J.en
dc.contributor.authorTasiopoulos, Anastasios J.en
dc.contributor.authorNastopoulos, Vassiliosen
dc.contributor.authorEscuer, Alberten
dc.contributor.authorPerlepes, Spyros P.en
dc.creatorKitos, Alexandros A.en
dc.creatorEfthymiou, Constantinos G.en
dc.creatorManos, Manolis J.en
dc.creatorTasiopoulos, Anastasios J.en
dc.creatorNastopoulos, Vassiliosen
dc.creatorEscuer, Alberten
dc.creatorPerlepes, Spyros P.en
dc.subjectChemistry, Inorganicen
dc.subjectChemistry, Physical and theoreticalen
dc.titleInteresting copper(ii)-assisted transformations of 2-acetylpyridine and 2-benzoylpyridine1en
dc.typeinfo:eu-repo/semantics/article Σχολή Θετικών και Εφαρμοσμένων Επιστημών / Faculty of Pure and Applied SciencesΤμήμα Χημείας / Department of Chemistry
dc.description.notes<p>ID: 1127en
dc.description.notesIn: Dalton transactions, Vol. 45, no. 3 ( 2016), p.1063-1077.en
dc.description.notesSummary: AbstractNovel CuII-assisted transformations have been observed in the reactions of copper(ii) sources and 2-pyridyl ketones.AbstractThe reactions of various copper(ii) sources with 2-acetylpyridine, (py)(me)CO, and 2-benzoylpyridine, (py)(ph)CO, under strongly basic conditions have been studied and novel ligand transformations have been discovered. Reaction of Cu(ClO4)2·6H2O and (py)(me)CO in the presence of NBu4nOMe (1 : 1 : 1) in CHCl3gave a mixture of [Cu2Cl2(HLA)2](ClO4)2(1) and [Cu2Cl2(LB)2(ClO4)2] (2), where HLAis 3-hydroxy-1,3-di(pyridin-2-yl)-butane-1-one and LBis the zwitterionic-type ligand 3-hydroxy-1-methyl-3-(pyridin-2-yl)-3H-indolizin-4-ium. The ligand HLAis formed through an aldol reaction-type mechanism, while the formation of LBtakes placeviaan intramolecular nucleophilic attack of the remote 2-pyridyl nitrogen atom on the positive carbonyl carbon of HLA, after the transformation of the latter through deprotonation and dehydration. The CuIIions in1are bridged by two 2.1111 HLAligands resulting in a long CuII⋯CuIIdistance (5.338 Å)en
dc.description.notesthe metal ions in2are triply bridged by the alkoxide oxygen atoms of the two 2.21 LBligands and one 2.1100 perchlorato group. The absence of α-hydrogens in (py)(ph)CO leads the reactivity of this ligand in the presence of CuIIto different pathways. The Cu(ClO4)2·6H2O/(py)(ph)CO/NBu4nOMe reaction mixture in MeOH/H2O (25 : 1 v/v) gave the dinuclear cationic complex [Cu2{(py)(ph)CO}2(LC)2](ClO4)2(3), where LC−is the anion of (methoxy)(phenyl)(pyridin-2-yl)methanol formedin situ viathe nucleophilic addition of MeO−to the carbonyl carbon of (py)(ph)CO upon CuIIcoordination. The CuIIions in the cation are doubly bridged by the deprotonated oxygen atoms of the two LC−ligands. Replacement of Cu(ClO4)2·6H2O with Cu(NO3)2·3H2O and NBu4nOMe with NMe4OH and the decrease of the H2O concentration in the above reaction system yielded the tetranuclear coordination cluster [Cu4(OMe)2(NO3)4{(py)(ph)CO}2(LC)2] (4). The CuIIcentres in this complex define a parallelogram. Two parallel sides of the parallelogram are each supported by deprotonated oxygen atoms belonging to a 2.21 LC−ligand and a 2.2 MeO−group. The metal ions that define each of the other two sides are singly bridged by an oxygen atom of a 2.210 nitrato group. No bridging exists between the CuIIions that define the two diagonals of the parallelogram. Replacement of MeOH with EtOH in the reaction system that gave4resulted in the dinuclear complex [Cu2(NO3)2(LD)2)(EtOH)] (5), LD−being the anion of (ethoxy)(phenyl)(pyridin-2-yl)methanol. The CuIIions are doubly bridged by the alkoxide oxygen atoms of the two 2.21 LD−ligands. The 1 : 1 : 1 Cu(NO3)2·3H2O/(py)(ph)CO/NMe4OH reaction system in CH3NO2gave the dinuclear complex [Cu2(NO3)2(LE)2] (6), where LE−is the anion of 2-nitro-1-phenyl-1-(pyridin-2-yl)ethanol. The OH−ion abstracts one of the methyl hydrogens of CH3NO2, and once the carbanion−:CH2NO2is formed it attacks the positive (δ+) carbonyl carbon of (py)(ph)COen
dc.description.notesas the carbanion forms the new C–C bond, the π electrons of the carbonyl group of the original ligand are transferred completely to oxygen forming the alkoxide-type ligand LE−. The CuIIions are doubly bridged by the alkoxide oxygen atoms of the two 2.21 LE−ligands. Simplified mechanistic views of the CuII-assisted formation of the transformed ligands are proposed. Dc magnetic susceptibility studies in the 2–300 K range for the representative complexes3–6reveal the presence of very strong antiferromagnetic CuII⋯CuIIexchange interactions in the dinuclear complexes3,5, and6and within the dimeric {Cu2(OMe)(NO3){(py)(ph)CO}(LC)}+subunits of4. The strong antiferromagnetic coupling is discussed in terms of the large Cu–O–Cu angles (101.0–102.9°) in the dinuclear, planar {Cu2O2} units/subunits of3–6.</p>en
dc.contributor.orcidTasiopoulos, Anastasios J. [0000-0002-4804-3822]
dc.contributor.orcidNastopoulos, Vassilios [0000-0003-4190-1342]
dc.contributor.orcidKitos, Alexandros A. [0000-0002-1431-3206]

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