Copper complexes of tripodal κ6N-donor ligands: A structural, EPR spectroscopic and electrochemical study

Trapp, Ina; Löble, Matthias W.; Meyer, Jens; Breher, Frank

doi:10.1016/j.ica.2011.02.045

Cited by 9 publications

(9 citation statements)

References 65 publications

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“…The spectral width is significantly smaller than the widths reported by Breher et al [29] for both the free ligand (∆δ = 1.30 ppm) and the respective copper(I) complex (∆δ = 1.15 ppm). By contrast, the resonances of the aromatic protons (and H 5 ) of the iron(II) complex are spread out over a 2.11 ppm range.…”

Section: Structural Characteristics Ofcontrasting

confidence: 68%

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Structural Dynamics of Spin Crossover in Iron(II) Complexes with Extended-Tripod Ligands

et al. 2017

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Selective manipulation of spin states in iron(II) complexes by thermal or photonic energy is a desirable goal in the context of developing molecular functional materials. As dynamic spin-state equilibration in isolated iron(II) complexes typically limits the lifetime of a given spin state to nanoseconds, synthetic strategies need to be developed that aim at inhibited relaxation. Herein we show that modulation of the reaction coordinate through careful selection of the ligand can indeed massively slow down dynamic exchange. Detailed structural analysis of [FeL] 2+ and [ZnL] 2+ (L: tris(1-methyl-2-{[pyridin-2-yl]-methylene}hydrazinyl)phosphane sulfide) with crystallographic and computational methods clearly reveals a unique trigonal-directing effect of the extended-tripod ligand L during spin crossover, which superimposes the ubiquitous [FeN 6 ] breathing with trigonal torsion, akin to the archetypal Bailar twist. As a consequence of the diverging reaction coordinates in [FeL] 2+ and in the tren-derived complex [Fe(tren)py 3 ] 2+ , their thermal barriers differ massively, although the spin crossover energies are close to identical. As is shown by time-resolved transient spectroscopy and dynamic 1 H-NMR line broadening, reference systems deriving from tren (tris-(2-aminoethyl)amine), which greatly lack such trigonal torsion, harbor very rapid spin-state exchange.

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Section: Structural Characteristics Ofcontrasting

confidence: 68%

“…Actually, L and derived ligands are known to facilitate the synthesis of trigonal prismatic complexes [29][30][31]. This correlation acknowledges previous structure-spin state correlations [32], that are based on structural-chemical considerations going back to the early 1970s [33][34][35][36][37][38][39][40][41][42].…”

Section: Introductionsupporting

confidence: 59%

Structural Dynamics of Spin Crossover in Iron(II) Complexes with Extended-Tripod Ligands

et al. 2017

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“…at 150 K. The significant divergence in bond lengths with respect to donor nature (đ(Fe-N pyr ) − đ(Fe-N aldimine ) ≈ 6 pm) points to a non-isotropic ligand field around iron(II); aldimine N is an intrinsically stronger donor than pyridine N. We note, however, that the order of metal−N bond lengths is inverted in the related copper(I) and copper(II) complexes of Breher et al [42].…”

Section: Solid-state Structuresmentioning

confidence: 60%

“…In sum, the coordination sphere can be classified as octahedral with significant trigonal distortion along the pseudo-threefold symmetry axis as defined by the vector S−P−Fe. At this point, it is important to note that Breher et al observed even more pronounced trigonal distortion after coordination of a very closely related hexa-imine ligand (R = H in the copper analogues of 1) to copper(II) ions [42], while the coordination of the respective copper(I) [42] and yttrium(III) [43] complexes is essentially trigonal-prismatic.…”

Section: Solid-state Structuresmentioning

confidence: 96%

Spin-state dynamics of a photochromic iron(II) complex and its immobilization on oxide surfaces via phenol anchors

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et al. 2015

Journal of Coordination Chemistry

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“…Substantial trigonal torsion along the SCO coordinate was expected to emerge through the combination of octahedral-directing iron(II) and trigonal-prismatic directing N 6 ligands L 1 – 3 (Scheme ). Ligands of this type actually have shown structural flexibility in response to the preference of the metal ion: While the ls iron(II) complex of the thiophosphoryl-capped ligand L 3 retains octahedral coordination, L 1 and its pyridine analogues previously provided broad access to trigonal-prismatic coordination. − …”

Section: Introductionmentioning

confidence: 99%

Molecular Spin Crossover in Slow Motion: Light-Induced Spin-State Transitions in Trigonal Prismatic Iron(II) Complexes

et al. 2016

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A straightforward access is provided to iron(II) complexes showing exceedingly slow spin-state interconversion by utilizing trigonal-prismatic directing ligands (L(n)) of the extended-tripod type. A detailed analysis of the interrelations between complex structure (X-ray diffraction, density functional theory) and electronic character (SQUID magnetometry, Mössbauer spectroscopy, UV/vis spectroscopy) of the iron(II) center in mononuclear complexes [FeL(n)] reveals spin crossover to occur along a coupled breathing/torsion reaction coordinate, shuttling the complex between the octahedral low-spin state and the trigonal-prismatic high-spin state along Bailar's trigonal twist pathway. We associate both the long spin-state lifetimes in the millisecond domain close to room temperature and the substantial barriers against thermal scrambling (Ea ≈ 33 kJ mol(-1), from Arrhenius analysis) with stereochemical constraints. In particular, the topology of the κ(6)N ligands controls the temporary and structural dynamics during spin crossover.

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Copper complexes of tripodal κ6N-donor ligands: A structural, EPR spectroscopic and electrochemical study

Cited by 9 publications

References 65 publications

Structural Dynamics of Spin Crossover in Iron(II) Complexes with Extended-Tripod Ligands

Structural Dynamics of Spin Crossover in Iron(II) Complexes with Extended-Tripod Ligands

Spin-state dynamics of a photochromic iron(II) complex and its immobilization on oxide surfaces via phenol anchors

Molecular Spin Crossover in Slow Motion: Light-Induced Spin-State Transitions in Trigonal Prismatic Iron(II) Complexes

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