Structure‐Property Relationships in Tricyanoferrate(III) Building Blocks and Trinuclear Cyanide‐Bridged Complexes

Zhang, Yuan‐Zhu; Malik, Uma P.; Quiggins, Benjamin; Nguyen, Hung Huy; Beedle, Christopher C.; Kovalev, Alexey; Clérac, Rodolphe; Hill, Stephen; Bythell, Benjamin J.; Holmes, Stephen M.

doi:10.1002/ejic.201600199

Cited by 12 publications

(15 citation statements)

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“…magnets. 10,11,12 Other promising application fields of pyrazolylborate complexes are catalysis 13,14,15,16,17 and the incorporation into polymers, 18 dendrimers, 19 molecular machines, 20 and metal-organic frameworks. 21 From the very first, these compounds have been studied by using paramagnetic NMR spectroscopy (pNMR) 1,22,23,24 and the initial results have been compiled.…”

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confidence: 99%

Paramagnetic Pyrazolylborate Complexes Tp₂M and Tp*₂M: ¹H, ¹³C, ¹¹B, and ¹⁴N NMR Spectra and First-Principles Studies of Chemical Shifts

et al. 2020

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Paramagnetic pyrazolylborates Tp2M and Tp*2M (M = Cu, Ni, Co, Fe, Mn, Cr, V) as well as [Tp2M] + and [Tp*2M] +(M = Fe, Cr, V) have been synthesized and their NMR spectra recorded. The 1 H signal shift ranges vary from ~30 ppm [Cu(II) and V(III)] to ~220 ppm [Co(II)] and the 13 C signal shift ranges from ~180 ppm [Fe(III)] to ~1150 ppm [Cr(II)]. The 11 B and 14 N shifts are ~360 ppm and ~730 ppm, respectively. Both negative and positive shifts have been observed for all nuclei. The narrow NMR signals of the Co(II), Fe(II), Fe(III), and V(III) derivatives provide resolved 13 C, 1 H couplings. All chemical shifts have been calculated from first-principles calculations on a modern version of Kurland-McGarvey theory which includes optimized structures, zero-field splittingand g-tensors, as well as signal shift contributions. Temperature dependence in the Fe(II) spin-crossover complex results from the equilibrium of the ground singlet and the excited quintet. We illustrate both the assignment and analysis capabilities, as well as the shortcomings of the current computational methodology. magnets. 10,11,12 Other promising application fields of pyrazolylborate complexes are catalysis 13,14,15,16,17 and the incorporation into polymers, 18 dendrimers, 19 molecular machines, 20 and metal-organic frameworks. 21 From the very first, these compounds have been studied by using paramagnetic NMR spectroscopy (pNMR) 1,22,23,24 and the initial results have been compiled. 25 Note that in the early literature the signs of pNMR signal shifts are inverted. Subsequent work, which shall be referred to below, is based on those findings and usually limited to proton NMR of Fe(II), Co(II), and Ni(II) derivatives. For three Co(II) derivatives Rouf, Mareš, and Vaara have tested theoretical and computational methods of calculating molecular properties, e.g., 1 H pNMR parameters. 26 Clearly, pyrazolylborate derivatives of many other paramagnetic ions exist or are conceivable and, given the diversity of this chemistry, some general questions from a pNMR point of view emerge: Which TpM-type compounds are worth investigating? What are the most useful nuclei? At what theoretical level can the spectra be reproduced? Do the calculated signal shifts support the signal assignment and thus the determination of the molecular and electronic structure? How are the signal shifts composed? Along these lines we have studied the parent compounds (Figure 1a) Tp2M (M = Cu, Ni, Co, Fe, Mn, Cr, and V), their monocations [Tp2M] + (M = Fe, Cr, and V), the methylated analogues Tp*2M (Tp* = hydrotris(3,5-dimethylpyrazole)borate, M = Cu, Ni, Co, Fe, Mn, Cr, and V), and [Tp*2M] + (M = Fe, Cr, and V). The present paper reports the 1 H, 13 C, 11 B, and 14 N NMR spectral data and their theoretical interpretation. To this end, first-principles calculations according to the recently redressed version 27,28 of the Kurland-McGarvey theory 29 have been carried out. These computations provide the respective overall pNMR signal shifts and their tensorial components, as well as co...

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confidence: 99%

Paramagnetic Pyrazolylborate Complexes Tp₂M and Tp*₂M: ¹H, ¹³C, ¹¹B, and ¹⁴N NMR Spectra and First-Principles Studies of Chemical Shifts

et al. 2020

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“…The variable-temperature magnetic susceptibility of 1 was recorded under an applied direct current (dc) field of 1 kOe over the temperature range of 2–300 K (Figure ). The χT product of 4.02 cm 3 K mol –1 at room temperature is in the normal range for two high-spin Ni(II) and two low-spin Fe(III) ions with unquenched orbital momentum . When the complex is cooled, the χT product increases continuously to a maximum of 8.04 cm 3 K mol –1 at 2 K, suggesting intramolecular ferromagnetic coupling between the metal ions.…”

Section: Resultsmentioning

confidence: 93%

“…As depicted in Figure , two peripheral [(pzTp)Fe(CN) 3 ] − anions are linked to the central double EO-azide-bridged [(bpzby)Ni(μ 2 -1,1-N 3 ) 2 Ni(bpzby)] 2+ subunit through the cyanides to form a centrosymmetric {Fe III –Ni II 2 –Fe III } rodlike structure. All of the Fe(III) and Ni(II) ions are located in the distorted octahedral coordination sphere, with an Fe–C/N bond length of 1.915(3)–1.982(2) Å and a Ni–N bond length of 2.028(2)–2.125(2) Å, typical for those observed in the related LS Fe(III) or HS Ni(II) species . The cyanide bridge features a linear arrangement with respect to the Fe(III) center [Fe1–C1–N1, 174.6(2)°], while the bridge is more bent on the Ni(II) site [C1–N1–Ni1, 157.94(2)°], giving an Fe–Ni distance of 4.986(6) Å.…”

Section: Resultsmentioning

confidence: 97%

“…Remarkably, the realization of good alignments (colinear or parallel) of the B···Fe vectors in these structures may help contribute to the SMM behavior, as evidenced in a series of Fe–Ni complexes ([Fe III 2 Ni II ], [Fe III 4 Ni II 2 ], and [Fe III 6 Ni II 3 ]) with a general motif of [Fe 2 Ni] n (Scheme ). It should be mentioned that the so-called 4,2-ribbon chain, being regarded as the infinite extension of the trinuclear [Fe III 2 Ni II ] units, represents a common structural archetype in favor of SCM behavior due to the well-arranged B···Fe vectors . As such, a series of SCMs with this architecture, {Fe III 2 M II } n (M = Fe, Co, Ni, or Cu), have been reported since the first cyanide-bridged one, {[(L)Fe III (CN) 4 ] 2 Co II (H 2 O) 2 } n ·4nH 2 O (L = 2,2′-bipyridine or 1,10-phenanthroline), was explored.…”

Section: Introductionmentioning

confidence: 99%

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Azido-Cyanide Mixed-Bridged Fe^III–Ni^II Complexes

et al. 2020

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The successful introduction of azide ions as secondary bridges into the FeIII–NiII cyanide system afforded two clusters and one unique 4(3),2-ribbon chain: [(bpzpy)2Ni2(μ2-1,1-N3)2{(pzTp)Fe(CN)3}2]·3H2O [1; bpzpy = 2,6-bis(pyrazol-1-yl)pyridine, and pzTp = tetrakis(pyrazolyl)borate], [(L1)2Ni4(μ3-1,1,1-OCH3)2(μ2-1,1-N3)2(H2O)2{(Tp)Fe(CN)3}2]·2CH3OH·H2O [2; Tp = hydrotris(pyrazolyl)borate, and HL1 = 2,6-bis{(2-hydroxypropylimino)methyl}-4-methylphenol], and [(L2)2Ni3(μ2-1,1-N3)4{(pzTp)Fe(CN)3}2] n (3; L2 = 2-{[phenyl(pyridin-2-yl)methylene]amino}ethan-1-amine). Both 1 and 2 feature the centrosymmetric {FeIII–NiII 2–FeIII} and {FeIII–NiII 4–FeIII} rodlike structures in which the two peripheral [(TpR)Fe(CN)3]− anions act as monodentate ligands via one cyanide group to link the central azide-bridged [Ni2] and [Ni4] subunit, respectively, while 3 displays an extended structure of the double-zigzag (4,2-ribbon) chain in which the double end-on azide-bridged trinuclear [Ni3] subunits serve as the 4-connected nodes. Magnetic study revealed that intramolecular ferromagnetic coupling is dominated by the azide or cyanide bridges in all of the complexes. Remarkably, complex 1 behaves as a single-molecule magnet with an effective energy barrier of 16.5 cm–1 at zero dc field, while complex 3 exhibits metamagnetism with a hidden spin canting property below 12 K.

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“…The Ni II ion features larger spin‐orbit coupling among 3d metal ions and shows the potential large zero field splitting in appropriate coordination environments, which makes it possible to behave as SMMs. Normally, the interactions between Fe III LS (LS = low‐spin) and Ni II HS (HS = high‐spin) ions exhibit ferromagnetic in the cyanide‐bridged Fe III –Ni II compounds, providing a chance for the construction of SMMs . It is well known that intermolecular interaction generally has some negative impact on SMM behavior and may suppress the slow relaxation of the magnetization , .…”

Section: Introductionmentioning

confidence: 99%

Single‐Molecule Magnet Behavior in Two Tetranuclear Cyanide‐bridged Fe^III₂Ni^II₂ Compounds

Liu

Jiao

Meng

et al. 2019

Zeitschrift anorg allge chemie

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Two tetranuclear cyanide‐bridged FeIII2NiII2 compounds [Ni2(L1)4Fe2(μ‐CN)4(CN)2(L2)2]·2ClO4·CH3OH·4H2O (1) and [Ni2(L1)4Fe2(μ‐CN)4(CN)2(L3)2]·2ClO4 (2) [L1 = 4,4′‐dichloro‐2,2′‐bipyridine; L2 = hydrotris(pyrazolyl)borate; L3 = tetrakis(pyrazolyl)borate] were synthesized. Magnetic measurements indicated that both two compounds showed single‐molecule magnet (SMM) behaviors with the relaxation energy barrier of Δ/kB = 68.9(8) K for 1 and 12.6(1) K for 2. Magneto‐structural analysis indicated that the intermolecular interactions played an important part in the slow magnetic relaxation behaviors.

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Structure‐Property Relationships in Tricyanoferrate(III) Building Blocks and Trinuclear Cyanide‐Bridged Complexes

Cited by 12 publications

References 122 publications

Paramagnetic Pyrazolylborate Complexes Tp₂M and Tp*₂M: ¹H, ¹³C, ¹¹B, and ¹⁴N NMR Spectra and First-Principles Studies of Chemical Shifts

Paramagnetic Pyrazolylborate Complexes Tp₂M and Tp*₂M: ¹H, ¹³C, ¹¹B, and ¹⁴N NMR Spectra and First-Principles Studies of Chemical Shifts

Azido-Cyanide Mixed-Bridged Fe^III–Ni^II Complexes

Single‐Molecule Magnet Behavior in Two Tetranuclear Cyanide‐bridged Fe^III₂Ni^II₂ Compounds

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Structure‐Property Relationships in Tricyanoferrate(III) Building Blocks and Trinuclear Cyanide‐Bridged Complexes

Cited by 12 publications

References 122 publications

Paramagnetic Pyrazolylborate Complexes Tp2M and Tp*2M: 1H, 13C, 11B, and 14N NMR Spectra and First-Principles Studies of Chemical Shifts

Paramagnetic Pyrazolylborate Complexes Tp2M and Tp*2M: 1H, 13C, 11B, and 14N NMR Spectra and First-Principles Studies of Chemical Shifts

Azido-Cyanide Mixed-Bridged FeIII–NiII Complexes

Single‐Molecule Magnet Behavior in Two Tetranuclear Cyanide‐bridged FeIII2NiII2 Compounds

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Paramagnetic Pyrazolylborate Complexes Tp₂M and Tp*₂M: ¹H, ¹³C, ¹¹B, and ¹⁴N NMR Spectra and First-Principles Studies of Chemical Shifts

Paramagnetic Pyrazolylborate Complexes Tp₂M and Tp*₂M: ¹H, ¹³C, ¹¹B, and ¹⁴N NMR Spectra and First-Principles Studies of Chemical Shifts

Azido-Cyanide Mixed-Bridged Fe^III–Ni^II Complexes

Single‐Molecule Magnet Behavior in Two Tetranuclear Cyanide‐bridged Fe^III₂Ni^II₂ Compounds