Synthesis, structure, and physical properties for a series of trigonal bipyramidal MII–Cl complexes with intramolecular hydrogen bonds

Sickerman, Nathaniel S.; Park, Young Jun; Ng, Gary K.-Y.; Bates, Jefferson E.; Hilkert, Mark; Ziller, Joseph W.; Furche, Filipp; Borovik, A. S.

doi:10.1039/c2dt12244h

Cited by 32 publications

(26 citation statements)

References 65 publications

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“…This observation is consistent with an H-bond interaction in solution between the protonated amine of the didpa ligand and the chloride bound to the zinc. 11,14,15,61 The same effect is seen in the 1 H NMR spectrum of 6, where the N−H resonance is Inorg. Chem.…”

Section: ■ Introductionsupporting

confidence: 68%

Probing the Protonation State and the Redox-Active Sites of Pendant Base Iron(II) and Zinc(II) Pyridinediimine Complexes

Delgado¹,

Sommer²,

Swanson³

et al. 2015

Inorg. Chem.

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Utilizing the pyridinediimine ligand [(2,6-(i)PrC6H3)N═CMe)(N((i)Pr)2C2H4)N═CMe)C5H3N] (didpa), the zinc(II) and iron(II) complexes Zn(didpa)Cl2 (1), Fe(didpa)Cl2 (2), [Zn(Hdidpa)Cl2][PF6] (3), [Fe(Hdidpa)Cl2][PF6] (4), Zn(didpa)Br2 (5), and [Zn(Hdidpa)Br2][PF6] (6), Fe(didpa)(CO)2 (7), and [Fe(Hdidpa)(CO)2][PF6] (8) were synthesized and characterized. These complexes allowed for the study of the secondary coordination sphere pendant base and the redox-activity of the didpa ligand scaffold. The protonated didpa ligand is capable of forming metal halogen hydrogen bonds (MHHBs) in complexes 3, 4, and 6. The solution behavior of the MHHBs was probed via pKa measurements and (1)H NMR titrations of 3 and 6 with solvents of varying H-bond accepting strength. The H-bond strength in 3 and 6 was calculated in silico to be 5.9 and 4.9 kcal/mol, respectively. The relationship between the protonation state and the ligand-based redox activity was probed utilizing 7 and 8, where the reduction potential of the didpa scaffold was found to shift by 105 mV upon protonation of the reduced ligand in Fe(didpa)(CO)2.

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Section: ■ Introductionsupporting

confidence: 68%

Probing the Protonation State and the Redox-Active Sites of Pendant Base Iron(II) and Zinc(II) Pyridinediimine Complexes

Delgado¹,

Sommer²,

Swanson³

et al. 2015

Inorg. Chem.

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“…This distortion is partially caused by the Jahn-Teller effect that should be present in a high-spin d 8 metal complex having local C 3 symmetry [53]. Another possible contributor to this distortion is the presence of intramolecular H-bonds formed between the urea hydrogen atoms of [H 3 buea] 3− and O-atom from the Ni II –OH unit.…”

Section: Resultsmentioning

confidence: 99%

Terminal NiII−OH/−OH2 complexes in trigonal bipyramidal geometries derived from H2O

2017

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The preparation and characterization of two NiII complexes are described, a terminal NiII–OH complex with the tripodal ligand tris[(N)-tertbutylureaylato)-N-ethyl)]aminato ([H3buea]3−) and a terminal Ni II–OH2 complex with the tripodal ligand N,N′,N″-[2,2′,2″-nitrilotris(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzenesulfonamido) ([MST]3−). For both complexes, the source of the –OH and –OH2 ligand is water. The salts K2[NiIIH3buea(OH)] and NMe4[NiIIMST(OH2)] were characterized using perpendicular-mode X-band electronic paramagnetic resonance, Fourier transform infrared, UV-visible spectroscopies, and its electrochemical properties were evaluated using cyclic voltammetry. The solid state structures of these complexes determined by X-ray diffraction methods reveal that they adopt a distorted trigonal bipyramidal geometry, an unusual structure for 5-coordinate NiII complexes. Moreover, the NiII–OH and NiII–OH2 units form intramolecular hydrogen bonding networks with the [H3buea]3− and [MST]3− ligands. The oxidation chemistry of these complexes was explored by treating the high-spin NiII compounds with one-electron oxidants. Species were formed with S = 1/2 spin ground states that are consistent with formation of monomeric NiIII species. While the formation of NiIII–OH complexes cannot be ruled out, the lack of observable O-H vibrations from the putative Ni–OH units suggest the possibility that other high valent Ni species are formed.

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“…31 The distortions from idealized tbp could be caused, in part, from a Jahn-Teller effect that should be present in high-spin d 6 metal complex having local C 3 symmetry. 32 This effect should be small because it arises from the d xz and d yz orbitals that are formally non-bonding. A larger contributor to the distortion is the contraction of the N1–Fe1–O1 angle, which in each complex is less than 175°.…”

Section: Resultsmentioning

confidence: 99%

Sulfonamido tripods: Tuning redox potentials via ligand modifications

Lau

Borovik

2015

Polyhedron

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A series of FeII–OH2 complexes were synthesized with ligands based on the tetradentate sulfonamido tripod N,N',N"-[2,2',2"-nitrilotris(ethane-2,1-diyl)]-tris-({R-Ph}-sulfonamido). These complexes differ by the substituent on the aryl rings and were fully characterized, including their molecular structures via X-ray diffraction methods. All the complexes were five-coordinate with trigonal bipyramidal geometry. A linear correlation was observed between the electronic effects of each ligand, given by the Hammett constants of the para-substituents, and the potential of the FeII/FeIII redox couple, which were determined using cyclic voltammetry. It was found that the range of redox potentials for the complexes spanned approximately 160 mV.

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Synthesis, structure, and physical properties for a series of trigonal bipyramidal MII–Cl complexes with intramolecular hydrogen bonds

Cited by 32 publications

References 65 publications

Probing the Protonation State and the Redox-Active Sites of Pendant Base Iron(II) and Zinc(II) Pyridinediimine Complexes

Probing the Protonation State and the Redox-Active Sites of Pendant Base Iron(II) and Zinc(II) Pyridinediimine Complexes

Terminal NiII−OH/−OH2 complexes in trigonal bipyramidal geometries derived from H2O

Sulfonamido tripods: Tuning redox potentials via ligand modifications

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