TY - JOUR
T1 - One-dimensional ferromagnetically coupled bimetallic chains constructed with trans-[Ru(acac)2(CN)2]-
T2 - Syntheses, structures, magnetic properties, and density functional theoretical study
AU - Guo, Jun Fang
AU - Wang, Xiu Teng
AU - Wang, Bing Wu
AU - Xu, Guan Cheng
AU - Gao, Song
AU - Szeto, Lap
AU - Wong, Wing Tak
AU - WONG, Wai Yeung
AU - Lau, Tai Chu
N1 - Copyright:
Copyright 2010 Elsevier B.V., All rights reserved.
PY - 2010/3/15
Y1 - 2010/3/15
N2 - Four cyano-bridged 1D bimetallic polymers have been prepared by using the paramagnetic building block trans-[Ru(acac)2(CN)2](Hacac= acetylacetone): {[{Ni(tren)}{Ru(acac)2(CN)2}][ClO 4].CH3OH}n (1) (tren = tris(2-aminoethyl)amine) , {[{Ni(cyclen)}{Ru(acac)2(CN)2)][ClO4]. CH3OH)n (2) (cyclen = 1,4,7,10-tetraazacyclododecane), {[{Fe(salen)}{Ru(acac)2(CN)2}]}n., (3) (salen2- = N,N'bis(salicylidene)-o-ethyldiamine dianion) and [{Mn(5,5'-Me2salen)}2{Ru(acac)2(CN)2}][Ru(acac) 2(CN)2]. 2CH3OH (4) (5.5'-Me 2salen=N,N'bis(5,5'-dimethylsalicylidene)-o-ethylenediimine). Compounds 1 and 2 are 1D, zigzagged NiRu chains that exhibit ferromagnetic coupling between NiII and RuIII ions through cyano bridges with J= + 1.92 cnr-1, zJ' =-1.37 cm-1, g=2.20 for 1 and J= + 0.85 cm-1, zJ' = -0.16 cm-1, g=2.24 for 2. Compound 3 has a 1D linear chain structure that exhibits intrachain ferromagnetic coupling (J=.+ 0.62 cm-1, zJ' = -0.09 cm-1, g=2.08), but antiferromagnetic coupling occurs between FeRu chains, leading to metamagnetic behavior with TN = 2.6 K. In compound 4, two MnIII ions are coordinated to trans-[Ru(acac)2(CN)2]- to form trinuclear Mn2Ru units, which are linked together by Jt-Jt stacking and weak Mn...O* interactions to form a 1D chain. Compound 4 shows slow magnetic relaxation below 3.0K with φ=0.25, characteristic of superparamagnetic behavior. The MnIII...RuIII coupling constant (through cyano bridges) and the MnIII...MnIII coupling constant (between the trimers) are +0.87 and +0.24 cm-1, respectively. Compound 4 is a novel single-chain magnet built from Mn 2Ru trimers through noncovalent interactions. Density functional theory (DFT) combined with the broken symmetry state method was used to calculate the molecular magnetic orbitais and the magnetic exchange interactions between RuIII and M (M = NiII, FeIII, and Mn III) ions. To explain the somewhat unexpected ferromagnetic coupling between low-spin RuIII and high-spin FeIII and Mn III ions in compounds 3 and 4, respectively, it is proposed that apart from the relative symmetries, the relative energies of the magnetic orbitais may also be important in determining the overall magnetic coupling in these bimetallic assemblies.
AB - Four cyano-bridged 1D bimetallic polymers have been prepared by using the paramagnetic building block trans-[Ru(acac)2(CN)2](Hacac= acetylacetone): {[{Ni(tren)}{Ru(acac)2(CN)2}][ClO 4].CH3OH}n (1) (tren = tris(2-aminoethyl)amine) , {[{Ni(cyclen)}{Ru(acac)2(CN)2)][ClO4]. CH3OH)n (2) (cyclen = 1,4,7,10-tetraazacyclododecane), {[{Fe(salen)}{Ru(acac)2(CN)2}]}n., (3) (salen2- = N,N'bis(salicylidene)-o-ethyldiamine dianion) and [{Mn(5,5'-Me2salen)}2{Ru(acac)2(CN)2}][Ru(acac) 2(CN)2]. 2CH3OH (4) (5.5'-Me 2salen=N,N'bis(5,5'-dimethylsalicylidene)-o-ethylenediimine). Compounds 1 and 2 are 1D, zigzagged NiRu chains that exhibit ferromagnetic coupling between NiII and RuIII ions through cyano bridges with J= + 1.92 cnr-1, zJ' =-1.37 cm-1, g=2.20 for 1 and J= + 0.85 cm-1, zJ' = -0.16 cm-1, g=2.24 for 2. Compound 3 has a 1D linear chain structure that exhibits intrachain ferromagnetic coupling (J=.+ 0.62 cm-1, zJ' = -0.09 cm-1, g=2.08), but antiferromagnetic coupling occurs between FeRu chains, leading to metamagnetic behavior with TN = 2.6 K. In compound 4, two MnIII ions are coordinated to trans-[Ru(acac)2(CN)2]- to form trinuclear Mn2Ru units, which are linked together by Jt-Jt stacking and weak Mn...O* interactions to form a 1D chain. Compound 4 shows slow magnetic relaxation below 3.0K with φ=0.25, characteristic of superparamagnetic behavior. The MnIII...RuIII coupling constant (through cyano bridges) and the MnIII...MnIII coupling constant (between the trimers) are +0.87 and +0.24 cm-1, respectively. Compound 4 is a novel single-chain magnet built from Mn 2Ru trimers through noncovalent interactions. Density functional theory (DFT) combined with the broken symmetry state method was used to calculate the molecular magnetic orbitais and the magnetic exchange interactions between RuIII and M (M = NiII, FeIII, and Mn III) ions. To explain the somewhat unexpected ferromagnetic coupling between low-spin RuIII and high-spin FeIII and Mn III ions in compounds 3 and 4, respectively, it is proposed that apart from the relative symmetries, the relative energies of the magnetic orbitais may also be important in determining the overall magnetic coupling in these bimetallic assemblies.
KW - Coordination modes
KW - Density functional calculations
KW - Magnetic properties
KW - Moleculebased magnets
KW - Ruthenium
KW - Singlechain magnets
UR - http://www.scopus.com/inward/record.url?scp=77949300995&partnerID=8YFLogxK
U2 - 10.1002/chem.200902047
DO - 10.1002/chem.200902047
M3 - Journal article
AN - SCOPUS:77949300995
SN - 0947-6539
VL - 16
SP - 3524
EP - 3535
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 11
ER -