TY - JOUR

T1 - Ligand Structure Effects on Molecular Assembly and Magnetic Properties of Copper(II) Complexes with 3-Pyridyl-Substituted Nitronyl Nitroxide Derivatives

AU - Sherstobitova, Tatiana

AU - Maryunina, Kseniya

AU - Tolstikov, Svyatoslav

AU - Letyagin, Gleb

AU - Romanenko, Galina

AU - Nishihara, Sadafumi

AU - Inoue, Katsuya

N1 - Publisher Copyright: Copyright © 2019 American Chemical Society. Copyright: Copyright 2019 Elsevier B.V., All rights reserved.

PY - 2019/10/22

Y1 - 2019/10/22

N2 - Reaction of Cu(hfac)2 with methyl- and bromo-3-pyridyl-substituted nitronyl nitroxides (LR) leads to assemble a diverse set of coordination complexes: mononuclear [Cu(hfac)2L2-Me], binuclear [{Cu(hfac)2}2(H2O)L2-Me], trinuclear [{Cu(hfac)2}3(L6-Br)2], pentanuclear [{Cu(hfac)2}5(L2-Me)2], and [{Cu(hfac)2}5(L2-Me)4], cocrystals [Cu(hfac)2(L2-Br)2]·[Cu(hfac)2(H2O)2] and [Cu(hfac)2(L2-Br)2]·2[Cu(hfac)2H2O], one-dimensional polymers [Cu(hfac)2L2-Br]n and [Cu(hfac)2L6-Br]n, and cyclic dimers [Cu(hfac)2L5-Me]2, [Cu(hfac)2L5-Br]2, and [Cu(hfac)2L6-Me]2. The molecular structures of the obtained complexes are strongly affected by the substituent type and its location in the pyridine heterocycle. Occupation of the second position of the pyridine ring increases the steric hindrance of both imine and nitroxide coordination sites of L2-R, which is favorable for the formation of various conformers and precipitation of complexes with different molecular structures. The pentanuclear [{Cu(hfac)2}5(L2-Me)2] and [{Cu(hfac)2}5(L2-Me)4] complexes do not have prior analogues and are valuable model objects for investigation of the mechanism of formation of various coordination polymers. The arrangement of long Cu-ONO bonds in {CuO6} square bipyramids due to the weakening nitroxide donor site in complexes, based on L2-Me, L2-Br, and L6-Br ligands, results in ferromagnetic exchange interactions between spins of Cu2+ ions and nitroxides. Complexes with substituents that do not considerably affect the coordination ability of ligands (L5-Me, L5-Br, and L6-Me) exhibit strong antiferromagnetic exchange interactions between spins of Cu2+ ions and nitroxides.

AB - Reaction of Cu(hfac)2 with methyl- and bromo-3-pyridyl-substituted nitronyl nitroxides (LR) leads to assemble a diverse set of coordination complexes: mononuclear [Cu(hfac)2L2-Me], binuclear [{Cu(hfac)2}2(H2O)L2-Me], trinuclear [{Cu(hfac)2}3(L6-Br)2], pentanuclear [{Cu(hfac)2}5(L2-Me)2], and [{Cu(hfac)2}5(L2-Me)4], cocrystals [Cu(hfac)2(L2-Br)2]·[Cu(hfac)2(H2O)2] and [Cu(hfac)2(L2-Br)2]·2[Cu(hfac)2H2O], one-dimensional polymers [Cu(hfac)2L2-Br]n and [Cu(hfac)2L6-Br]n, and cyclic dimers [Cu(hfac)2L5-Me]2, [Cu(hfac)2L5-Br]2, and [Cu(hfac)2L6-Me]2. The molecular structures of the obtained complexes are strongly affected by the substituent type and its location in the pyridine heterocycle. Occupation of the second position of the pyridine ring increases the steric hindrance of both imine and nitroxide coordination sites of L2-R, which is favorable for the formation of various conformers and precipitation of complexes with different molecular structures. The pentanuclear [{Cu(hfac)2}5(L2-Me)2] and [{Cu(hfac)2}5(L2-Me)4] complexes do not have prior analogues and are valuable model objects for investigation of the mechanism of formation of various coordination polymers. The arrangement of long Cu-ONO bonds in {CuO6} square bipyramids due to the weakening nitroxide donor site in complexes, based on L2-Me, L2-Br, and L6-Br ligands, results in ferromagnetic exchange interactions between spins of Cu2+ ions and nitroxides. Complexes with substituents that do not considerably affect the coordination ability of ligands (L5-Me, L5-Br, and L6-Me) exhibit strong antiferromagnetic exchange interactions between spins of Cu2+ ions and nitroxides.

KW - SPIN-TRANSITION

KW - FREE-RADICALS

KW - CRYSTAL

KW - COORDINATION

KW - CU(HFAC)(2)

KW - DESIGN

UR - http://www.scopus.com/inward/record.url?scp=85073161667&partnerID=8YFLogxK

U2 - 10.1021/acsomega.9b01575

DO - 10.1021/acsomega.9b01575

M3 - Article

C2 - 31656889

AN - SCOPUS:85073161667

VL - 4

SP - 17160

EP - 17170

JO - ACS Omega

JF - ACS Omega

SN - 2470-1343

IS - 17

ER -