Abstract
This chapter deals with single-molecule magnets (SMMs) obtained from heterometallic Co(II)/4f complexes. The design principles involved in building various types of heterometallic complexes are discussed along with their magnetic properties. A large group of hybrid Co(II)/4f complexes of varying nuclearity are discussed. Some examples of Co(III)/4f complexes are also presented.
All the authors contributed equally to this work.
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Keywords
- Cluster complexes
- Cobalt/lanthanide complexes
- Lanthanides
- Magnetism
- Single molecule magnet
- Slow relaxation of magnetization
1 Introduction
In the previous chapter while discussing the complexes containing Co(II)-based SMMs/SIMs, it was noted that the ground state S value is fixed, and the D value is the sole parameter to fine-tune the magnetic behavior. Because of factors such as (1) the small and fixed “S” value associated with Co(II) ions, (2) quenching of orbital angular momentum due to the ligand field, (3) ligand-induced structural distortion, and (4) nuclear hyperfine interaction, faster relaxation mechanism such as QTM can become operative in homometallic Co(II) complexes [1,2,3]. To some extent, these factors can be overcome by employing multidentate ligand or compartmental ligand to link Co(II) along with other suitable lanthanide ions simultaneously in a heterometallic ensemble. This will be the focus of this chapter.
The first lanthanide-based SMM in 2003, a mononuclear [Pc2Tb] complex, phthalocyanine (Pc), has attracted a great interest toward the use of lanthanide ions in SMMs [4]. Accordingly, the first heterometallic SMM, a Cu2Tb2 complex, was reported in 2004 [5]. The heterometallic tetrameric complex was isolated by the reaction of K[CuL] and [TbIII(hfac)3(H2O)2] (1) where H3L = 1-(2-hydroxybenzamido)-2-(2-hydroxy-3-methoxy-benzylideneamino)-ethane. The crystal structure of the complex with molecular formula [CuIILTbIII(hfac)2]2 is shown in Fig. 1. Instead of the [CuL]− precursor, if the analogous [NiL]− precursor [NiIILTbIII(hfac)2]2 (2) is used, where the paramagnetic Cu(II) ion was replaced with diamagnetic NiII affording an opportunity to compare the role of Cu(II) ion in 1.
Complex 1 shows ferromagnetic interaction between the CuII and TbIII ions with a positive Weiss constant (θ = +14.3 K) as originally proposed by Gatteschi and co-workers [6]. Complex 1 showed SMM behavior [(τ 0) = 2.7 × 10−8 s; U eff = Δ/k B) = 21 K; T B = 1.2 K). However, hysteresis was not observed at the measured temperatures, viz., above 2 K.
Under similar condition, complex 2 reveals a simple paramagnetic behavior that may be due to the magnetic anisotropy and/or intermolecular antiferromagnetic interaction and/or dipolar interaction. AC susceptibility measurement of 2 does not display χ M″ signal which may be due to the fast QTM at zero magnetic field. Possibly the presence of ferromagnetic exchange interaction between Cu(II) and Tb(III) ion is likely the reason for the observed SMM behavior in 1 (H DC = 0).
Based on these early forays, the advantage of using 3d–4f heterometallic complexes were reasoned as: (1) relatively high spin ground state can be achieved using less number of metal ions compared to larger polynuclear 3d metal complexes, and (2) anisotropy can be harvested through the lanthanide ions by exploiting its unquenched orbital angular momentum.
Presence of QTM is a major problem in incorporating lanthanide ion although the single-ion magnetic anisotropy of these ions is generally large as compared to the 3d metal ions. Due to this fact, the blocking temperature remains well below 5 K in majority of the 3d–4f metal complexes [7]. However, this disadvantage can be minimized by enhancing the exchange interaction between 3d and 4f ions. This phenomenon was first reported by Murray and co-workers by enhancing the exchange interaction between the Cr(III) and Dy(III) ion in a heterometallic [CrIII 2LnIII 2(OMe)2(mdea)2(O2CPh)4(NO3)2] (3), LnIII = Pr, Nd, Gd, Tb, Ho, and Er and mdea = N-methyl diethanolaminato(2−) butterfly complex where QTM is significantly reduced/quenched which facilitate in enhancing the blocking temperature [8, 9]. Due to the arrest/quenching of magnetization, opening of a hysteresis loop is generally observed unlike in transition metal clusters (Fig. 2). Similarly, heterometallic Ni2Dy2(4) complex is found to show a similar behavior, where QTM is found to be suppressed completely resulting in a zero-field SMM [10]. The anisotropic barrier extracted for the later complex (19 cm−1) in zero applied DC magnetic field, and the one estimated in the presence of external magnetic field (18.9 cm−1) is found out to be similar indicating that QTM is efficiently suppressed. In both cases (Cr2Dy2 and Ni2Dy2), quenching of QTM is attributed to the presence of enhanced exchange interaction compared to the other 3d–4f complexes reported in the literature. Further, it has been proposed that a larger ∠Ni–O–Dy angle and smaller distortion in the dihedral plane formed by Ni–O–Dy–O are the recipe for increasing the ferromagnetic exchange.
The presence of 3d ion in near vicinity of Ln(III) ion environment is not the only option, but paramagnetic bridging ligands can play a crucial role in increasing the exchange interaction. This has been elegantly proven in a series of Ln2 dimers linked through unusual N2 3− radical ligand (with a blocking temperature of 14 K for the Tb2 analogue) [11, 12].
Since several 3d–4f metal complexes are known in the literature, we will restrict to Co(II)/4f SMM reported in the literature in this chapter. We will also discuss some examples of Co(III)/4f complexes. Before this a brief introduction on the nature of interaction between the 3d and 4f metal ions is in order.
To ascertain qualitatively the nature of exchange interaction between the 3d and the 4f metal ion, Andruh et al. proposed an empirical approach by considering Ni–Ln (Ln = Dy or Pr) dimeric complexes [13]. In such complexes, the total magnetic moment experimentally observed is the combination of magnetic moment contribution from individual metal ions (e.g., nickel and Ln(III) ion) along with the exchange couple state. Hence, by subtracting the individual metal ion contribution from the total magnetic moment, the masked nature of interaction will be clearly reflected by plotting the temperature-dependent Δχ MT value.
The empirical equation is
For example, the presence of ferromagnetic exchange interaction observed between Ni(II) and Dy(III) complexes in Ni2Dy2 tetrameter is revealed using the empirical equation shown above.
For a system with ferromagnetic interaction, the Δχ MT plot will raise at low temperature in positive direction, while for an antiferromagnetic interaction, the plot will plunge into negative Δχ MT value. The general trend noticed in case of Cu(II)–Ln or Ni(II)–Ln complexes are: (1) a ferromagnetic exchange interaction is observed if Ln(III) valence shell contains ≥f7 electrons, and (2) an antiferromagnetic coupling exists if Ln(III) valence shell electron become less than 7. This scenario is witnessed in many such complexes, which is very well exemplified [13]. We have noticed recently that a similar trend is also observed in Co(II) containing 4f complexes. Hence, targeting Co(II)–Ln(III) (where LnIII≥f7) is an ideal approach to reveal a new generation of SMMs. Accordingly, various Co(II)/(III)–Ln(III) SMMs reported in literature have been overviewed below.
2 Hybrid Co–4f Complexes as SMMs
This section deals with various examples on heterometallic Co(II)/Ln(III) and Co(III)/Ln(III) complexes. In the case of Co(III)/Ln(III) complexes, the magnetic properties are entirely due to the lanthanide ion.
Based on the above insight, several heterometallic 3d/4f complexes were investigated [7, 14,15,16,17,18,19,20,21,22,23]. The first Co/Ln SMM, [L2CoII 2Gd][NO3] (5), was reported by Chandrasekhar and co-workers. The complex was assembled using a phosphorus-based tris-hydrazone ligand (LH3) and contains a linear array of metal ions [24] (Fig. 3).
The zero-field SMM behavior of this complex was confirmed by AC susceptibility measurements (Fig. 4): U eff = 27.2 K and τ 0 = 1.7 × 10−7 s.
Several other structurally analogous trinuclear complexes {[L2CoII 2Ln][X]} [Ln = Eu, X = Cl; Ln = Tb, Dy and Ho, X = NO3] were also prepared, all of which except the EuIII analogue were shown to be SMMs [25]. Table 1 summarizes the magnetic data for all of these complexes.
Following these first examples, there have been several studies on such heterometallic Co(II)/Ln(III) and Co(III)/Ln(III) complexes. In the subsequent sections, we will discuss these based on the nuclearity of the complexes. Only such complexes will be discussed where there has been a demonstration of SMM behavior.
2.1 Dinuclear Complexes
The preparation of the heterometallic complexes discussed in this and subsequent sections is dependent on the use of the so-called compartmental ligands which have specificity toward either the transition metal ion or the lanthanide metal ion.
A cyanido-bridged complex, [{DyIII(3-OHpy)2(H2O)4][CoIII(CN)6}] (9), was reported by the self-assembly reaction involving DyIII–3-hydroxypyridine (3-OHpy) complexes with hexacyanidocobaltate(III). This complex, which can be considered as single-ion magnet, shows SMM behavior with a high U eff of 266 cm−1(≈385 K) and a τ 0 = 3.2 × 10−11 s above 23 K at H DC = 0 Oe. Moreover, magnetization hysteresis loops are observed below 6 K with a field sweep rate of 10 Oe s−1 [26].
In contrast to the above, a CoII/YIII complex, [CoII(μ-L)(μ-OAc)Y(NO3)2] (10), was prepared using a compartmental ligand N,N′,N″-trimethyl-N,N″-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H2L) [27] (Fig. 5).
Although these complexes do not show zero-field SMM behavior, AC measurements at H DC = 1,000 Oe revealed them to be SMMs. An effort was made to modulate the structural features by varying the bridging ligand which did not result in any significant change in the magnetic properties. An interesting aspect of these complexes is that all of them have been shown to have a positive D and in spite of this they exhibit a field-induced SMM behavior, rather intriguingly [28]. Rationale for the observation of field-induced slow relaxation of magnetization with easy plane anisotropy was explained in the previous chapter.
Another family of dinuclear Co–Ln complexes, [CoIILnIII(L)(DBM)3] [Ln = Y (11), Dy (12) and Gd (13)], is known; the ligands used were N,N′-dimethyl-N,N′-(2-hydroxy-3-methoxy-5-methyl-benzyl)ethylenediamine (LH2) and the anion of 1,3-diphenyl-propane-1,3-dione (DBM−) [29] (Fig. 6).
These complexes also reveal a positive D (S = 3/2, g = 2.39, D = 10.3 cm−1 and E = 4 × 10−4 cm−1 for CoII−Y analogue); the latter reveals a field-induced single-molecule magnet (SMM) behavior (Fig. 7).
MII−Ln binuclear complexes, [MII(3-MeOsaltn)(MeOH)(OAc)Ln(hfac)2] (MII = Co, Ni, Cu and Zn; Ln = GdIII, TbIII, DyIII, LaIII) were prepared by using N,N′-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato (3-MeOsaltn) and hexafluoroacetylacetonato (hfac) [30]. The MII−Ln magnetic interactions are ferromagnetic when MII = (CuII, NiII, and CoII) and Ln = (GdIII, TbIII, and DyIII). The D value was found to be positive for the CoII/La analogue. These complexes however did not display zero-field SMM behavior.
Table 2 summarizes the magnetic data for some dinuclear Co(II)/Ln(III) complexes.
2.2 Trinuclear Cobalt–Lanthanide SMMs
In contrast to the trinuclear complexes described above involving a phosphorus-supported ligand, another series, [CoIII 2Dy(L)2(μ-O2CCH3)2(H2O)3](NO3) (22) (LH3 = 2-methoxy-6-[{2-(2-hydroxyethylamino)ethylimino}-methyl]phenol), is known. This complex showed slow relaxation of magnetization at 1,000 Oe applied DC field [(U/k B) = 88 K; (τ 0) = 1.0 × 10−8 s) [35] (Fig. 8).
In these examples, the analogous Tb(III) complex (23) has a lower U eff = 15.6 K. It has been suggested that this may be due to the fact that while Dy(III) is a Kramers ion, the integer m j level of Tb(III) is likely to trigger the ground state tunneling [36].
[CoIILn2 III] complexes, [LnIII 2CoII(C7H5O2)8] [Ln = Dy (24) and Tb (25)] containing an in situ generated salicylaldehyde as the ligand, have been prepared [37] (Fig. 9).
Both 24 and 25 display SMM behavior at zero DC field, although 25 does not show a clear maxima in the χ′′ vs T plot. For 24, two relaxation processes could be delineated: relaxation at the higher temperature region (above 5 K) being suggested as being associated with the excited Kramer doublets of individual DyIII ions, while at the low temperature region (below 5 K), the weak coupling between CoII and DyIII appears to predominate [38].
Complexes containing Co(III), [CoIII 2Dy(hmb)2(CH3O)2(OAc)3] [Ln = Dy (26) and Lu (27)], could be prepared using 2-hydroxy-3-methoxybenzylidene benzohydrazide (H2hmb) [39] (Fig. 10).
Frequency-dependent AC susceptibility measurements for 26 at 500 Oe applied DC field provide the energy barrier (U eff) = 5.5 K and τ 0 = 2.7 × 10−5 s.
The magnetic properties of trinuclear Co(II)/Ln(III) and Co(III)/Ln(III) SMMs are summarized in Table 3.
2.3 Tetranuclear Cobalt–Lanthanide SMMs
A [CoII 2Dy2(L)4(NO3)2(THF)2] (39) complex having a butterfly/defect-dicubane topology was assembled using 2-[(2-hydroxy-phenylimino)-methyl]-6-methoxyphenol) (H2L) [45] (Fig. 11).
Analysis of the frequency-dependent AC measurements in zero DC field revealed the presence of two thermally activated relaxation regimes [(U eff) of 11.0 cm−1 (15.8 K); τ 0 = 7.7 × 10−4 s in the temperature range 1.6–8 K and (U eff) of 82.1 cm−1 (118.12 K); τ 0 = 6.2 × 10−7 s between 18 and 22 K]. Interestingly, this complex shows hysteresis below 3 K at a sweep rate of 235 mTs−1 (Fig. 12). The coercivity of the hysteresis loops increases with decreasing temperature and increasing field sweep rate. The loops display steplike features below 1.5 K, indicating the possibility of resonant QTM below this temperature.
Replacement of the solvent molecules coordinated with the Co2+ centers to form [CoII 2Dy2(L)4(NO3)2(MeOH)2] (40) and [CoII 2Dy2(L)4(NO3)2(DMF)2] (41) did not affect the compounds from being SMMs [46]. An analogous Zn2Dy2 (42) complex has also been assembled. A comparison of the magnetic properties in the complexes 39–42 is given in Table 4 (Fig. 13).
A tetranuclear complex [CoII 2Dy2(L)4(NO3)2(DMF)2] (43) possessing a butterfly/defect-dicubane topology such as described above could be obtained by the use of (E )-2-ethoxy-6-(((2-hydroxyphenyl)imino)methyl)phenol (H2L) [47] (Fig. 14).
The magnetic properties of the [CoII 2Dy2] analogue and the analogous [Dy2Zn2(L)4(NO3)2(CH3OH)2] (44) and [Dy2MnIII 2(L)4(NO3)2(DMF)2] (45) reveal that they are SMMs (Table 5).
The range of ligands that can afford tetranuclear complexes seem to be quite large. Thus, the complexes [CoII 2Ln2(Hhms)2(CH3COO)6(CH3OH)2(H2O)2](NO3)2[Ln = DyIII (46), GdIII (47), and YIII (48)] could be prepared by using (2-hydroxy-3-methoxybenzylidene)-semicarbazide (H2hms) [48] (Fig. 15).
Complex 46 shows temperature as well as frequency-dependent out-of-phase (χ″) signals (τ 0 = 6.4 × 10−6 s; U eff = 6.7 K at zero DC field; τ 0 = 3.2 × 10−6 s and U eff = 13.8 K at H DC = 800 Oe in the range 2.0–5.5 K). Theoretical CASSCF calculation studies revealed that the Dy–Dy interactions are largely ferromagnetic and dominant, while the exchange coupling (J exch) of Dy–Co in {CoII 2DyIII 2} is antiferromagnetic. Interestingly, in the analogous {NiII 2DyIII 2}(49) complex, ferromagnetic exchange between NiII and DyIII ions is found which is more conducive to zero-field single-molecule magnet behavior. The magnetic properties of tetranuclear complexes are summarized in Table 6.
Many tetranuclear complexes could also be assembled by the use of ethanolamine ligands. Thus, the complexes, [CoIII 2LnIII 2(OH)2(bdea)2(acac)2(NO3)4] [Ln = Tb (59) and Dy(60)] and bdeaH2 = n-butyldiethanolamine) containing two Co(III) ions, were prepared [57] (Fig. 16).
Analysis of the AC susceptibility data for 60 allowed the extraction of the following parameters: U eff = 169 K and τ o = 1.47 × 10−7 s above 20 K where the relaxation is thermally activated. As the temperature is decreased, a slight curvature appears in the Arrhenius plot of ln(τ) vs 1/T but does not become temperature independent at any point, indicating that a pure quantum regime is not observed within the timescale and temperature range of experiment. In contrast to complex 60, 59 does not show SMM characteristics at zero DC field. However, upon application of 5,000 Oe DC field, a frequency-dependent maxima in the plot of χ M′′ vs T is seen. This phenomenon is a common feature for non-Kramers TbIII-based complexes and is due to fast zero-field quantum tunneling of the magnetization between the sublevels. The non-Kramers ion generally allows the direct mixing of opposing projections of the ground state angular momentum/spin projections by the crystal field, so that tunneling pathways become readily accessible [58,59,60,61,62,63].
Other examples of tetranuclear heterometallic complexes [{LnIII 2CoIII 2(OMe)2 (teaH)2(O2CPh)4(MeOH)4}(NO3)2][LnIII 2CoIII 2(OMe)2(teaH)2(O2CPh)4(MeOH)2 (NO3)2] [Ln = Gd (61), Tb (62) and Dy (63)] were prepared using triethanolamine (teaH3). Interestingly two tetranuclear units containing [LnIII 2CoIII 2(OMe)2 (teaH)2(O2CPh)4(MeOH)4](NO3)2 and [LnIII 2CoIII 2(OMe)2(teaH)2(O2CPh)4(MeOH)2 (NO3)2] are present within the same crystal [64] (Fig. 17).
AC susceptibility measurements in a zero DC field reveal the SMM behavior for the DyIII analogue with the following characteristics above 8.5 K: (U eff) of 88.8 K (~61 cm−1) and τ 0 = 5.64 × 10−8 s. But below 8.5 K, the Arrhenius plot deviates slightly from linear behavior indicating the existence of QTM. However, applying field up to 1,000 Oe does not change significantly the peak maxima in the χ M″ vs T plot, indicating that QTM is inefficient in this system.
Among other tetranuclear complexes assembled using triethanolamine as the ligand, containing two Co(III), are [DyIII 2CoIII 2(OMe)2(teaH)2(O2CPh)4(MeOH)4](NO3)2 and [DyIII 2CoIII 2(OMe)2(teaH)2(O2CPh)4(MeOH)2(NO3)2] (63), [DyIII 2CoIII 2 (OMe)2(dea)2(O2CPh)4(MeOH)4](NO3)2 (64), [DyIII 2CoIII 2(OMe)2(mdea)2(O2CPh)4 (NO3)2] (65), [DyIII 2CoIII 2(OMe)2(bdea)2(O2CPh)4(MeOH)4](NO3)2, and [DyIII 2CoIII 2 (OMe)2(bdea)2(O2CPh)4(MeOH)2(NO3)2] (66) (teaH3 = triethanolamine, deaH2 = diethanolamine, mdeaH2 = N-methyldiethanolamine, and bdeaH2 = N-n-butyldiethanolamine). The extracted magnetic parameters, from the AC measurements of these complexes, are summarized in Table 7 [65].
In addition to the aforementioned complexes, complex [CoIII 2DyIII 2(OMe)2(teaH)2(Piv)6] (67) can also be prepared using triethanolamine ligand. This complex displays SMM behavior with U eff = 51 K; τ 0 = 6.1 × 10−7 s and τ QT = 7.3 s in the range 4.5–7.5 K [U eff = 127 K; τ 0 = 1.2 × 10−9 s; C Ram = 1.7 × 10−3 in the range of 7.5–9.5 K] [66] (Fig. 18).
For this complex, the energy level splitting under crystal field of the DyIII ground J = 15/2 state was determined (Fig. 19). The thermal barrier for the fast relaxation pathways through m J = ±13/2 and m J = ±11/2 from ground state should be 39 and 104 cm−1. These values compare quite well with the experimental U eff = 35 cm−1 (51 K) and 88 cm−1 (127 K) values obtained from AC data (Fig. 20).
A summary of magnetization relaxation dynamics for this [CoIII 2LnIII 2] family (67−70) is shown in Table 8 [67].
N-n-butyldiethanolamine (bdeaH2) and N-methyldiethanolamine (mdeaH2) were used as ligands for preparing [Co2 IIIDy2 III(OMe)2(O2CPh-2-Cl)4(bdea)2(NO3)2] (71), [Co2 IIIDy2 III(OMe)2(O2CPh-4-tBu)4(bdea)2(NO3)(MeOH)3](NO3) (72), [Co2 IIICoIILnIII(OH)(O2CPh-4-OH)(bdea)3(NO3)3(MeOH)] [Ln = Dy (73), Gd (74)], [Co2 IIIDy2 III(OMe)(OH)(O2CPh-2-CF3)4(bdea)2(NO3)2] (75), and [Co2 IIIDy2 III(mdea)4(hfacac)3(O2CCF3)(H2O)] (76) [68]. A summary of magnetization relaxation dynamics of these complexes (71−76) is enlisted in Table 9.
Similarly a series of SMMs [CoIII 2LnIII 2(μ 3-OH)2(o-tol)4(mdea)2(NO3)2] [Ln = Dy (77), Tb (78), Ho (79)] [69], [DyIII 2CoIII 2(OH)2(teaH)2(acac)6] (80), [DyIII 2CoIII 2(OH)2(bdea)2(acac)6](81), and [DyIII 2CoIII 2(OH)2(edea)2(acac)6] (82) (teaH3 = triethanolamine, bdeaH2 = N-n-butyldiethanolamine, edeaH2 = N-ethyldiethanolamine and acacH = acetylacetone) [70] are reported. The detailed parameters associated with their SMM behavior are summarized in Table 10 (Fig. 21).
2.4 Higher Nuclearity Cobalt−Lanthanide SMMs
In this section we will deal with complexes whose nuclearity is greater than 4. Only representative examples will be discussed. The magnetic data for these complexes are tabulated in Table 11. A hexanuclear complex [Dy4CoIII 2(HL2)2(μ 3-OH)2(piv)10(OH2)2] complex (86) was prepared by the use of 2-(2,3 dihydroxpropyliminomethyl)-6-methoxyphenol(H3L2) and pivalic acid as ligands. The molecule contains two dimeric Dy(III) sub-units on either side of a dimeric Co(III) motif. Each of the Co(III) centers along with a Dy(III) is involved in a defect cubane structural motif [83] (Fig. 22).
The field dependence of magnetization shows a rapid increase of M values at lower DC field, indicating the presence of intramolecular ferromagnetic interactions between spin carriers. The Arrhenius plot obtained from the frequency-dependent AC susceptibility measurements provides the signature of SMM with an energy gap (U eff) of 18.4 cm−1 (26.47 K) and a pre-exponential factor τ 0 = 8.7 × 10−6 s at H DC = 0. The Cole–Cole plot provides the α value within the 0.19–0.13, indicating a single relaxation time is mainly involved and is independent of the temperature.
Two octanuclear complexes, [CoIII 4Dy4(μ-OH)4(μ 3-OMe)4{O2CC(CH3)3}4 (tea)4(H2O)4] (87) and [CoIII 4DyIII 4(μ-F)4(μ 3-OH)4(o-tol)8(mdea)4] (88) (tea3− = triply deprotonated triethanolamine; mdea2− = doubly deprotonated N-methyldiethanolamine; o-tol = o-toluate), have been recently reported. The central core of the octanuclear ensemble consists of a [Dy(III)]4 motif and is surrounded by four Co(III) ions. Like in the previous case, each of the Co(III) along with two Dy(III) centers is involved in a defect cubane motif [84] (Fig. 23).
Complex 87 reveals frequency-dependent “tails” in the out-of-phase susceptibility against temperature plots below 3 K at H DC = 0 Oe. This behavior does not improve even after application of fields up to 5,000 Oe. But for complex 88, at H DC = 5,000 Oe, the corresponding energy barrier U eff = 39 cm−1 and pre-exponential factor τ 0 = 1.0 × 10−6 s can be obtained between 8 and 10.5 K.
A dodecanuclear complex [CoII 2Dy10(L)4(OAc)16(SCN)2(CH3CN)2(H2O)4 (OH)2(μ 3-OH)4][Co(SCN)4(H2O)]2 (89) was assembled by using the multifunctional ligand, 1,2-bis(2-hydroxy-3-methoxybenzylidene) hydrazine (H2L). In contrast to the examples discussed above, this complex contains Co(II) [85] (Fig. 24).
The nature of the CoII–Dy and Dy–Dy interactions could not be delineated with certainty. However, the authors, based on the AC susceptibility measurements, suggest that this complex has a SMM behavior.
3 Summary
Co(II) is a promising 3d metal ion with first-order orbital contribution that has been investigated for its interesting magnetic properties. The combination of Co(II) and lanthanide ions in the form of heterometallic complexes leads to an interesting array of complexes where the role of the ligand seems to be extremely crucial in modulating the nuclearity and the coordination geometry. While there has been considerable progress in this field, it is anticipated that appropriate design of complexes can lead to SIMs and SMMs with even better properties. One crucial element that is missing from the studies carried out so far seems to be a strong theoretical input. Once such an understanding is in place, it becomes easier for synthetic chemists to make appropriate designs for assembling SMMs with superior properties.
Change history
26 September 2019
In the Chapter opener page, the spelling of the author is inadvertently misspelt as Vadapalli Chandrsekhar, which is now corrected as Vadapalli Chandrasekhar.
References
Murrie M (2010) Chem Soc Rev 39:1986–1995
Craig GA, Murrie M (2015) Chem Soc Rev 44:2135–2147
Frost JM, Harriman KLM, Murugesu M (2016) Chem Sci 7:2470–2491
Ishikawa N, Sugita M, Ishikawa T, Koshihara S-Y, Kaizu Y (2003) J Am Chem Soc 125:8694–8695
Osa S, Kido T, Matsumoto N, Re N, Pochaba A, Mrozinski J (2004) J Am Chem Soc 126:420–421
Bencini A, Benelli C, Caneschi A, Carlin RL, Dei A, Gatteschi D (1985) J Am Chem Soc 107:8128–8136
Woodruff DN, Winpenny REP, Layfield RA (2013) Chem Rev 113:5110–5148
Langley SK, Wielechowski DP, Chilton NF, Moubaraki B, Murray KS (2015) Inorg Chem 54:10497–10503
Langley SK, Wielechowski DP, Vieru V, Chilton NF, Moubaraki B, Abrahams BF, Chibotaru LF, Murray KS (2013) Angew Chem Int Ed 52:12014–12019
Ahmed N, Das C, Vaidya S, Langley SK, Murray KS, Shanmugam M (2014) Chem Eur J 20:14235–14239
Rinehart JD, Fang M, Evans WJ, Long JR (2011) Nat Chem 3:538
Rinehart JD, Fang M, Evans WJ, Long JR (2011) J Am Chem Soc 133:14236–14239
Pasatoiu TD, Sutter J-P, Madalan AM, Fellah FZC, Duhayon C, Andruh M (2011) Inorg Chem 50:5890–5898
Winpenny REP (1998) Chem Soc Rev 27:447–452
Benelli C, Gatteschi D (2002) Chem Rev 102:2369–2388
Mishra A, Wernsdorfer W, Abboud KA, Christou G (2004) J Am Chem Soc 126:15648–15649
Tanase S, Reedijk J (2006) Coord Chem Rev 250:2501–2510
Andruh M, Costes J-P, Diaz C, Gao S (2009) Inorg Chem 48:3342–3359
Sessoli R, Powell AK (2009) Coord Chem Rev 253:2328–2341
Karotsis G, Kennedy S, Teat SJ, Beavers CM, Fowler DA, Morales JJ, Evangelisti M, Dalgarno SJ, Brechin EK (2010) J Am Chem Soc 132:12983–12990
Papatriantafyllopoulou C, Wernsdorfer W, Abboud KA, Christou G (2011) Inorg Chem 50:421–423
Sharples JW, Collison D (2014) Coord Chem Rev 260:1–20
Rosado Piquer L, Sanudo EC (2015) Dalton Trans 44:8771–8780
Chandrasekhar V, Pandian BM, Azhakar R, Vittal JJ, Clérac R (2007) Inorg Chem 46:5140–5142
Chandrasekhar V, Pandian BM, Vittal JJ, Clérac R (2009) Inorg Chem 48:1148–1157
Chorazy S, Rams M, Nakabayashi K, Sieklucka B, Ohkoshi S-I (2016) Chem Eur J 22:7371–7375
Colacio E, Ruiz J, Ruiz E, Cremades E, Krzystek J, Carretta S, Cano J, Guidi T, Wernsdorfer W, Brechin EK (2013) Angew Chem Int Ed 52:9130–9134
Palacios MA, Nehrkorn J, Suturina EA, Ruiz E, Gómez-Coca S, Holldack K, Schnegg A, Krzystek J, Moreno JM, Colacio E (2017) Chem Eur J 23:11649–11661
Xie Q-W, Wu S-Q, Shi W-B, Liu C-M, Cui A-L, Kou H-Z (2014) Dalton Trans 43:11309–11316
Towatari M, Nishi K, Fujinami T, Matsumoto N, Sunatsuki Y, Kojima M, Mochida N, Ishida T, Re N, Mrozinski J (2013) Inorg Chem 52:6160–6178
Wang X, Li H, Sun J, Yang M, Li C, Li L (2017) New J Chem 41:2973–2979
Dolai M, Ali M, Titis J, Boca R (2015) Dalton Trans 44:13242–13249
Hazra S, Titis J, Valigura D, Boca R, Mohanta S (2016) Dalton Trans 45:7510–7520
Bartolomé J, Filoti G, Kuncser V, Schinteie G, Mereacre V, Anson CE, Powell AK, Prodius D, Turta C (2009) Phys Rev B 80:014430
Goura J, Brambleby J, Goddard P, Chandrasekhar V (2015) Chem Eur J 21:4926–4930
Goura J, Brambleby J, Topping CV, Goddard PA, Suriya Narayanan R, Bar AK, Chandrasekhar V (2016) Dalton Trans 45:9235–9249
Li X-L, Min F-Y, Wang C, Lin S-Y, Liu Z, Tang J (2015) Inorg Chem 54:4337–4344
Guo Y-N, Xu G-F, Wernsdorfer W, Ungur L, Guo Y, Tang J, Zhang H-J, Chibotaru LF, Powell AK (2011) J Am Chem Soc 133:11948–11951
Xue S, Ungur L, Guo Y-N, Tang J, Chibotaru LF (2014) Inorg Chem 53:12658–12663
Modak R, Sikdar Y, Thuijs AE, Christou G, Goswami S (2016) Inorg Chem 55:10192–10202
Chandrasekhar V, Das S, Dey A, Hossain S, Kundu S, Colacio E (2014) Eur J Inorg Chem 2014:397–406
Zhou J-M, Shi W, Xu N, Cheng P (2013) Cryst Growth Des 13:1218–1225
Yamaguchi T, Costes J-P, Kishima Y, Kojima M, Sunatsuki Y, Bréfuel N, Tuchagues J-P, Vendier L, Wernsdorfer W (2010) Inorg Chem 49:9125–9135
Liu C-M, Zhang D-Q, Hao X, Zhu D-B (2014) Chem Asian J 9:1847–1853
Mondal KC, Sundt A, Lan Y, Kostakis GE, Waldmann O, Ungur L, Chibotaru LF, Anson CE, Powell AK (2012) Angew Chem Int Ed 51:7550–7554
Peng Y, Mereacre V, Anson CE, Powell AK (2017) Dalton Trans 46:5337–5343
Li J, Wei R-M, Pu T-C, Cao F, Yang L, Han Y, Zhang Y-Q, Zuo J-L, Song Y (2017) Inorg Chem Front 4:114–122
Wu H, Li M, Zhang S, Ke H, Zhang Y, Zhuang G, Wang W, Wei Q, Xie G, Chen S (2017) Inorg Chem 56:11387–11397
Zhao X-Q, Lan Y, Zhao B, Cheng P, Anson CE, Powell AK (2010) Dalton Trans 39:4911–4917
Costes J-P, Vendier L, Wernsdorfer W (2011) Dalton Trans 40:1700–1706
Wu J, Zhao L, Zhang P, Zhang L, Guo M, Tang J (2015) Dalton Trans 44:11935–11942
Moreno Pineda E, Chilton NF, Tuna F, Winpenny REP, McInnes EJL (2015) Inorg Chem 54:5930–5941
Abtab SMT, Majee MC, Maity M, Titiš J, Boča R, Chaudhury M (2014) Inorg Chem 53:1295–1306
Xu G-F, Gamez P, Tang J, Clérac R, Guo Y-N, Guo Y (2012) Inorg Chem 51:5693–5698
Zhao L, Wu J, Xue S, Tang J (2012) Chem Asian J 7:2419–2423
Huang Y-G, Wang X-T, Jiang F-L, Gao S, Wu M-Y, Gao Q, Wei W, Hong M-C (2008) Chem Eur J 14:10340–10347
Langley SK, Chilton NF, Moubaraki B, Murray KS (2013) Chem Commun 49:6965–6967
Rinehart JD, Long JR (2011) Chem Sci 2:2078–2085
Sorace L, Benelli C, Gatteschi D (2011) Chem Soc Rev 40:3092–3104
Bar AK, Pichon C, Sutter J-P (2016) Coord Chem Rev 308:346–380
Habib F, Murugesu M (2013) Chem Soc Rev 42:3278–3288
Zhang P, Guo Y-N, Tang J (2013) Coord Chem Rev 257:1728–1763
Gómez-Coca S, Aravena D, Morales R, Ruiz E (2015) Coord Chem Rev 289-290:379–392
Langley SK, Chilton NF, Ungur L, Moubaraki B, Chibotaru LF, Murray KS (2012) Inorg Chem 51:11873–11881
Langley SK, Ungur L, Chilton NF, Moubaraki B, Chibotaru LF, Murray KS (2014) Inorg Chem 53:4303–4315
Funes AV, Carrella L, Rentschler E, Albores P (2014) Dalton Trans 43:2361–2364
Funes AV, Carrella L, Rechkemmer Y, van Slageren J, Rentschler E, Albores P (2017) Dalton Trans 46:3400–3409
Langley SK, Le C, Ungur L, Moubaraki B, Abrahams BF, Chibotaru LF, Murray KS (2015) Inorg Chem 54:3631–3642
Vignesh KR, Langley SK, Murray KS, Rajaraman G (2017) Inorg Chem 56:2518–2532
Langley SK, Chilton NF, Moubaraki B, Murray KS (2015) Inorg Chem Front 2:867–875
Langley SK, Chilton NF, Moubaraki B, Murray KS (2013) Inorg Chem 52:7183–7192
Fang M, Shi P-F, Zhao B, Jiang D-X, Cheng P, Shi W (2012) Dalton Trans 41:6820–6826
Liu Y, Chen Z, Ren J, Zhao X-Q, Cheng P, Zhao B (2012) Inorg Chem 51:7433–7435
Orfanoudaki M, Tamiolakis I, Siczek M, Lis T, Armatas GS, Pergantis SA, Milios CJ (2011) Dalton Trans 40:4793–4796
Sopasis GJ, Orfanoudaki M, Zarmpas P, Philippidis A, Siczek M, Lis T, O’Brien JR, Milios CJ (2012) Inorg Chem 51:1170–1179
Zhao X-Q, Wang J, Bao D-X, Xiang S, Liu Y-J, Li Y-C (2017) Dalton Trans 46:2196–2203
Langley SK, Chilton NF, Moubaraki B, Murray KS (2013) Polyhedron 66:48–55
Xiang H, Lan Y, Li H-Y, Jiang L, Lu T-B, Anson CE, Powell AK (2010) Dalton Trans 39:4737–4739
Sheikh JA, Goswami S, Konar S (2014) Dalton Trans 43:14577–14585
Feuersenger J, Prodius D, Mereacre V, Clérac R, Anson CE, Powell AK (2013) Polyhedron 66:257–263
Jhan S-Y, Huang S-H, Yang C-I, Tsai H-L (2013) Polyhedron 66:222–227
Tian C-B, Yuan D-Q, Han Y-H, Li Z-H, Lin P, Du S-W (2014) Inorg Chem Front 1:695–704
Zou H-H, Sheng L-B, Liang F-P, Chen Z-L, Zhang Y-Q (2015) Dalton Trans 44:18544–18552
Vignesh KR, Langley SK, Murray KS, Rajaraman G (2017) Chem Eur J 23:1654–1666
Zou L-F, Zhao L, Guo Y-N, Yu G-M, Guo Y, Tang J, Li Y-H (2011) Chem Commun 47:8659–8661
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Dey, A., Tripathi, S., Shanmugam, M., Narayanan, R.S., Chandrasekhar, V. (2018). Cobalt(II)/(III)–Lanthanide(III) Complexes as Molecular Magnets. In: Chandrasekhar, V., Pointillart, F. (eds) Organometallic Magnets . Topics in Organometallic Chemistry, vol 64. Springer, Cham. https://doi.org/10.1007/3418_2018_9
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