Preparations and properties of nitrosyl complexes of iron tetramethylcyclam. X-ray structures of [Fe(C14H32N4)NO](BF4)2, a S = 3/2-1/2 spin-equilibrium complex, and [Fe(C14H32N4)(NO)(OH)](ClO4)2.CH3CN

Hodges, Keith D.; Wollmann, Ronald G.; Kessel, Stephen L.; Hendrickson, D. N.; Derveer, D. G. Van; Barefield, E. Kent

doi:10.1021/ja00498a019

Cited by 66 publications

(48 citation statements)

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“…S3). 14,17 Thus, NO 2 was successfully accounted for and recovered in good yield, and this result strongly supports our proposed reaction profile as given in Scheme 1.…”

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confidence: 85%

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An isoelectronic NO dioxygenase reaction using a nonheme iron(iii)-peroxo complex and nitrosonium ion

et al. 2014

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“…S3). 14,17 Thus, NO 2 was successfully accounted for and recovered in good yield, and this result strongly supports our proposed reaction profile as given in Scheme 1.…”

supporting

confidence: 85%

“…S1), which are indicative of a d 5 electron configuration typically observed for high-spin ( S = 5/2) iron(III) species. 14 The yield of 4 was estimated to be ~67% §…”

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confidence: 99%

An isoelectronic NO dioxygenase reaction using a nonheme iron(iii)-peroxo complex and nitrosonium ion

et al. 2014

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“…In addition, the change in the appearance of the NO Fig. 13 Tetradentate N 4 -donating ligands stretching vibration in the IR spectra with decreasing temperature is consistent with electrons pairing up in a lower lying molecular orbital that contains a contribution from the p* orbitals of the nitrosyl entity [167]. Related five-coordinate FeN 3 O 2 spin crossover systems involving the nitrosyl anion and N,N 0 -ethylenebis(salicylideneiminate) have also been described (see below).…”

Section: Complexes Of Tetradentate N 4 -Donating Ligandsmentioning

confidence: 74%

“…Using tmcyclam a five-coordinate compound has been obtained [167]. The X-ray structure of [Fe(tmcyclam)(NO)](BF 4 ) 2 has been determined at room temperature, revealing an Fe(III) ion in a distorted tetragonal pyramid consisting of the four nitrogen atoms of the macrocycle (average Fe-N=2.165 ) together with a nitrosyl anion in the apical position.…”

Section: Complexes Of Tetradentate N 4 -Donating Ligandsmentioning

confidence: 99%

Iron(III) Spin Crossover Compounds

Koningsbruggen

Maeda

Oshio

2004

Topics in Current Chemistry

175

130

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In this chapter, selected results obtained so far on Fe(III) spin crossover compounds are summarized and discussed. Fe(III) spin transition materials of ligands containing chalcogen donor atoms are considered with emphasis on those of N,N-disubstituted-dithiocarbamates, N,N-disubstituted-XY-carbamates (XY=SO, SSe, SeSe), X-xanthates (X=O, S), monothio-b-diketonates and X-semicarbazones (X=S, Se). In addition, attention is directed to Fe(III) spin crossover systems of multidentate Schiff base-type ligands. Examples of spin inter-conversion in Fe(III) compounds induced by light irradiation are given.

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“…The plots of log( K sc ) versus 1/ T showed a good linear relationship, from which the thermodynamic parameters were obtained as Δ H =16.9 kJ mol −1 and Δ S =66.6 J mol −1 K −1 . Although the spin‐crossover process between the S =1/2 and S =3/2 states is not unprecedented in iron( III ) complexes,8, 9 this is, to the best of our knowledge, the first example in iron( III ) porphyrin complexes.…”

Section: Mössbauer Parameters and Spin State (S) Of 1–5mentioning

confidence: 85%

Saddle‐Shaped Six‐Coordinate Iron( III ) Porphyrin Complexes Showing a Novel Spin Crossover between S =1/2 and S =3/2 Spin States

Ikeue¹,

Ohgo²,

Yamaguchi³

et al. 2001

Angewandte Chemie

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Spin states of iron(iii) porphyrins are controlled by the number and nature of axial ligands. [1] The coordination of nitrogen bases such as imidazole (HIm) and pyridine results in the formation of low-spin (S 1/2) six-coordinate complexes. In contrast, anionic ligands such as Cl À and F À lead to the formation of five-coordinate high-spin (S 5/2) complexes. Maltempo discussed a spin-admixed S 3/2, 5/2 state on the basis of quantum mechanical calculations, and suggested that the S 3/2 state is an important contributor to the spin state of certain bacterial heme proteins known as cytochromes c'. [2] We and others recently reported that highly nonplanar (porphyrinato)iron(iii) complexes with weak axial ligands show a quite pure intermediate spin state. [3,4] The results were ascribed to the short FeÀN por bonds of the nonplanar porphyrin rings and the weak coordination ability of the axial ligands. [5] We therefore expected that the spin state of nonplanar [Fe III (oetpp)L 2 ]ClO 4 (1 ± 5) could change from N Fe N Et Et Et Et Ph Ph Ph Ph Et Et Et L L Et N 5: L = thf [Fe(Oetpp)L 2 ]ClO 4 1: L = HIm 2: L = dmap + 3: L = py 4: L = 4-CNpy ClO 4 -the pure S 1/2 to the pure S 3/2 state as the axial ligand changes from strong HIm to weak THF; the order of the coordination ability is HIm b dmap b py b 4-CNpy b thf. [6] Of particular interest are the spin states of 2 ± 4 because the axial ligands of these complexes are ranked between HIm and THF. Table 1 lists the Mössbauer parameters, isomer shift (IS; relative to a-iron foil at 290 K), and quadrupole splitting (QS) measured at ambient and liquid nitrogen temperatures. The QS values for 1 and 2 at ambient temperature were within the range of low-spin complexes. [7] The IS and QS values for 4 (0.37 and 3.26 mm s À1 , respectively) were close to those for 5 (0.41 and 3.65 mm s À1 ); 5 has been fully characterized as the quite pure intermediate-spin complex. [4] Thus, from the viewpoint of Mössbauer spectroscopy, 1 and 2 are the lowspin complexes, while 4 is the intermediate-spin complex at ambient temperature. Figure 1 shows the Mössbauer spectra of 3 and 4 taken at ambient temperature and 80 K. The features change as the temperature is lowered. Complex 4 exhibited a new doublet (site B) below 230 K, and the relative intensities for this site increased on decreasing the temperature. The values for sites A and B are in the range of intermediate-spin and low-spin complexes, respectively, and both spin states co-exist at low temperature. This observation implies the occurrence of a novel spin-crossover process [Eq. (1)]. [8,9] low spin (S 1/2) > intermediate spin (S 3/2) (1)

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Preparations and properties of nitrosyl complexes of iron tetramethylcyclam. X-ray structures of [Fe(C14H32N4)NO](BF4)2, a S = 3/2-1/2 spin-equilibrium complex, and [Fe(C14H32N4)(NO)(OH)](ClO4)2.CH3CN

Cited by 66 publications

References 0 publications

An isoelectronic NO dioxygenase reaction using a nonheme iron(iii)-peroxo complex and nitrosonium ion

An isoelectronic NO dioxygenase reaction using a nonheme iron(iii)-peroxo complex and nitrosonium ion

Iron(III) Spin Crossover Compounds

Saddle‐Shaped Six‐Coordinate Iron( III ) Porphyrin Complexes Showing a Novel Spin Crossover between S =1/2 and S =3/2 Spin States

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