Manganese tetraphenylporphyrin bromide and iodide. Studies of structures and magnetic properties

Bone, Alexandria N.; Stavretis, Shelby E.; Krzystek, J.; Liu, Zhiming; Chen, Qiang; Gai, Zheng; Wang, Xiaoping; Steren, Carlos A.; Powers, Xian B.; Podlesnyak, A.; Chen, Xue-Tai; Telser, Joshua; Zhou, H. D.; Xue, Zi‐Ling

doi:10.1016/j.poly.2020.114488

Cited by 13 publications

(14 citation statements)

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“…Substitution of the amido halogen substituent has minimal impact on the D value, with D becoming slightly less negative from 13 a to 13 d to 13 e . This trend is significantly more dramatic in the corresponding MnX(TPP) series in which the halogen is bound directly to the Mn center [22] . This observation is a consequence of the extensive spin–orbit coupling of heavier donors [28] .…”

Section: Resultsmentioning

confidence: 97%

“…The rhombicity does show a more significant dependence on the halogen identity, where 13 a is the least rhombic and 13 e is the most. We hypothesize that the high rhombicity value of MnNXTs(TPP) is due to the Ts‐N‐X apical unit breaking the fourfold symmetry observed in manganese tetrapyrroles, which generally feature rhombicity values close to zero, even in the case of corroles/corrolazines, which lack the true fourfold symmetry of the porphyrin macrocycle [21–25, 27] . Qualitatively, Mn−N π‐bonding from N p x (filled N lone pair) to Mn d xz (half‐filled), but not correspondingly from N p y to Mn d yz would distinguish the in‐plane x and y directions (the principal ZFS direction is along z , normal to the porphyrin plane) [21a] …”

Section: Resultsmentioning

confidence: 99%

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Nitrene Photochemistry of Manganese N‐Haloamides**

et al. 2021

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Manganese complexes supported by macrocyclic tetrapyrrole ligands represent an important platform for nitrene transfer catalysis and have been applied to both C−H amination and olefin aziridination catalysis. The reactivity of the transient high‐valent Mn nitrenoids that mediate these processes renders characterization of these species challenging. Here we report the synthesis and nitrene transfer photochemistry of a family of MnIII N‐haloamide complexes. The S=2 N‐haloamide complexes are characterized by 1H NMR, UV‐vis, IR, high‐frequency and ‐field EPR (HFEPR) spectroscopies, and single‐crystal X‐ray diffraction. Photolysis of these complexes results in the formal transfer of a nitrene equivalent to both C−H bonds, such as the α‐C−H bonds of tetrahydrofuran, and olefinic substrates, such as styrene, to afford aminated and aziridinated products, respectively. Low‐temperature spectroscopy and analysis of kinetic isotope effects for C−H amination indicate halogen‐dependent photoreactivity: Photolysis of N‐chloroamides proceeds via initial cleavage of the Mn−N bond to generate MnII and amidyl radical intermediates; in contrast, photolysis of N‐iodoamides proceeds via N−I cleavage to generate a MnIV nitrenoid (i.e., {MnNR}7 species). These results establish N‐haloamide ligands as viable precursors in the photosynthesis of metal nitrenes and highlight the power of ligand design to provide access to reactive intermediates in group‐transfer catalysis.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Nitrene Photochemistry of Manganese N‐Haloamides**

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“…126 It is also noted that the reported AC susceptibility measurements of Co-TODA at 2.0−3.0 K give U eff = 11 cm −1 , 30 spectra of forward-scattering data and backscattering data are given in Figure 6. Since phonons are bosons following the Bose−Einstein statistics, 36,53,54,67,70,71,128 the Bose correction applies a frequency-and temperature-dependent normalization factor such that INS spectra measured at different temperatures are brought to a similar level for comparison. In other words, the spectrum is divided by the phonon population factor, which facilitates the comparison of the various spectra collected at different temperatures.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Advanced Spectroscopic and Computational Studies of a Cobalt(II) Coordination Polymer with Single-Ion-Magnet Properties

et al. 2022

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Two-dimensional (2D) coordination polymer (CP) [Co III (CN) 6 ] 2 [Co II (TODA)] 3 •7H 2 O (TODA = 1,4,10-trioxa-7,13diazacyclopentadecane, Co-TODA) was reported earlier to show field-induced slow magnetic relaxation, displaying single-ion magnet (SIM) behaviors. Most SIMs are molecular compounds with fewer adopting coordination polymer (CP) or metal−organic framework (MOF) structures. In the current work, magnetic and phonon properties of Co-TODA have been studied by advanced spectroscopies and computations. The combined use of far-IR magneto-spectroscopy (FIRMS) and variable-temperature (VT) high-frequency and -field electron paramagnetic resonance (HFEPR) gives spin Hamiltonian (SH) parameters: Axial zerofield splitting (ZFS) parameter D as +38.0(1.0) ≤ D ≪ +40.2(1.0) cm −1 and rhombic ZFS parameter E as 0 ≪ |E| ≤ 7.3(1.0) cm −1 , showing that Co-TODA has the easy-plane magnetic anisotropy. Two Co II centers in the CP, as determined by synchrotron single-crystal X-ray diffraction at 15(2) K, show similar magnetic properties indistinguishable in FIRMS at 5.3(3) K or in HFEPR at 5−150 K. Ab initio calculations explore the origin of the magnetic anisotropy and magnetostructural correlations. VT inelastic neutron scattering (INS) spectra of Co-TODA have been obtained to show the phonon properties of the CP. Density functional theory (DFT) calculations, giving both a calculated INS spectrum and spin distributions in Co-TODA, demonstrate that, compared with other high-spin Co II complexes, the larger the spin density on a metal ion, the larger the ZFS in the complex. Pulsed X-band EPR studies probe relaxations of the Co II ions from the M S = +1/2 to −1/2 state in the ground Kramers doublet (KD), yielding spin−lattice (T 1 ) and spin−spin relaxation (T 2 ) times. The work reported here highlights the versatility and power of the spectroscopic techniques and computations in the characterization of magnetic and phonon properties of a CP and the understanding of its magnetic anisotropy.

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“…We hypothesize that the high rhombicity value of MnNXTs(TPP) is due to the Ts-N-X apical unit breaking the four-fold symmetry observed in manganese tetrapyrroles, which generally feature rhombicity values close to zero, even in the case of corroles/corrolazines, which lack the true four-fold symmetry of the porphyrin macrocycle. [20,[22][23]25] Qualitatively, Mn-N p-bonding from N px (filled N lone pair) to Mn dxz (half-filled), but not correspondingly from N py to Mn dyz would distinguish the in-plane x and y directions (the principal ZFS direction is along z, normal to the porphyrin plane). [20a] Figure 5.…”

Section: Synthesis and Characterization Sequential Treatment Of Porphyrin-supported Mn(iii)mentioning

confidence: 99%

Nitrene Photochemistry of Manganese N-Haloamides

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Das

et al. 2021

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Manganese complexes supported by macrocyclic tetrapyrrole ligands represent an important platform for nitrene transfer catalysis and have been applied to both C-H amination and olefin aziridination catalysis. The reactivity of the transient high-valent Mn nitrenoids that mediate these processes renders characterization of these species challenging. Here we report the synthesis and nitrene transfer photochemistry of a family of Mn(III) N-haloamide complexes. The S = 2 Nhaloamide complexes are characterized by 1 H NMR, UV-vis, IR, high-frequency and -field EPR (HFEPR) spectroscopies, and single-crystal X-ray diffraction. Photolysis of these complexes results in the formal transfer of a nitrene equivalent to both C-H bonds, such as the a-C-H bonds of tetrahydrofuran, and olefinic substrates, such as styrene, to afford aminated and aziridinated products, respectively. Low-temperature spectroscopy and analysis of kinetic isotope effects for C-H amination indicate halogen-dependent photoreactivity: Photolysis of N-chloroamides proceeds via initial cleavage of the Mn-N bond to generate Mn(II) and amidyl radical intermediates; in contrast, photolysis of N-iodoamides proceeds via N-I cleavage to generate a Mn(IV) nitrenoid (i.e., {MnNR} 7 species). These results establish N-haloamide ligands as viable precursors in the photosynthesis of metal nitrenes and highlight the power of ligand design to provide access to reactive intermediates in group-transfer catalysis.

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Manganese tetraphenylporphyrin bromide and iodide. Studies of structures and magnetic properties

Cited by 13 publications

References 79 publications

Nitrene Photochemistry of Manganese N‐Haloamides**

Nitrene Photochemistry of Manganese N‐Haloamides**

Advanced Spectroscopic and Computational Studies of a Cobalt(II) Coordination Polymer with Single-Ion-Magnet Properties

Nitrene Photochemistry of Manganese N-Haloamides

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