Synthesis, crystal structures, Mössbauer spectra, and redox properties of binuclear and tetranuclear iron-sulfur nitrosyl clusters

Санина, Н. А.; Chuev, I. I.; Алдошин, С. М.; Ovanesyan, N. S.; Strelets, V. V.; Geletii, Yurii V.

doi:10.1007/bf02494773

Cited by 19 publications

(22 citation statements)

References 10 publications

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“…[51] Roussins red salt anion, a bis-{Fe(NO) 2 (Figure 7), which couple antiferromagnetically to give a diamagnetic ground state. [16,52] The OLYP-optimized geometry of [Fe 2 (NO) 4 A C H T U N G T R E N N U N G (m-S) 2 ] 2À agrees well with the X-ray crystal structure, [52] with only a slight overestimation of the Fe-Fe distance (Table 4). However, due to the very strong coupling between the metal centers in 3, the OLYP wavefunction collapses to a spin-restricted solution,…”

Section: Bond Length []/ Angle [8] [A]supporting

confidence: 64%

“…Roussin’s red salt anion, a bis‐{Fe(NO) 2 } 9 complex : Roussin’s red salt anion, [Fe 2 (NO) 4 (μ‐S) 2 ] 2− ( 3 ), is made up of two S =1/2 {Fe(NO) 2 } 9 units (Figure 7), which couple antiferromagnetically to give a diamagnetic ground state 16. 52 The OLYP‐optimized geometry of [Fe 2 (NO) 4 (μ‐S) 2 ] 2− agrees well with the X‐ray crystal structure,52 with only a slight overestimation of the Fe–Fe distance (Table 4). However, due to the very strong coupling between the metal centers in 3 , the OLYP wavefunction collapses to a spin‐restricted solution, as opposed to a broken‐symmetry state (this is a general characteristic of pure functionals; see the computational details section).…”

Section: Resultsmentioning

confidence: 99%

“…All eight orbital pairs show significant delocalization over both {Fe(NO) 2 } 9 units (three of these orbital pairs are shown in Figure 9 B-D). 3 ] À : Roussins black salt anion (4, Figure 10) [17,52,55,56] exhibits C 3v symmetry, with one apical {FeNO} 7 unit and three basal {Fe(NO) 2 } 9 units. Antiferromagnetic coupling between the apical S = 3/2 and the three basal S = 1/2 units results in an overall diamagnetic ground state.…”

Section: Bond Length []/ Angle [8] [A]mentioning

confidence: 99%

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Spin Coupling in Roussin’s Red and Black Salts

Hopmann

Noodleman

Ghosh

2010

Chemistry A European J

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Although DFT calculations have provided a first-order electronic-structural description for Roussin's red and black salts, a detailed study of spin coupling in these species has yet to be reported. Such an analysis is presented here for the first time, based on broken-symmetry density functional theory (DFT, chiefly OLYP/STO-TZP) calculations. Both the Noodleman and Yamaguchi formulas were used to evaluate the Heisenberg coupling constants (J). Three nitrosylated binuclear clusters were studied: [Fe 2 (2), and Roussin's red salt anion [Fe 2 (NO) 4 (μ-S) 2 ] 2− (3). Although the Heisenberg J for 1 is small (≈10 2 cm −1 ), 2 and 3 exhibit J values that are at least an order of magnitude higher (≈ 10 3 cm −1 ), where the J values refer to the following Heisenberg spin Hamiltonian:. For Roussin's black salt anion, [Fe 4 (NO) 7 (μ 3 -S) 3 ] − (4), the Heisenberg spin Hamiltonian describing spin coupling between the {FeNO} 7 unit (S A =3/2) and the three {Fe(NO) 2 } 9 units (S B =S C =S D =1/2) in [Fe 4 (NO) 7 (μ 3 -S) 3 ] − was assumed to have the form:, in which J 12 corresponds to the interaction between the apical iron and a basal iron, and J 22 refers to that between any two basal iron centers. Although the basal-basal coupling constant J 22 was found to be small (≈ 10 2 cm −1 ), the apical-basal coupling constant J 12 is some forty times higher (≈ 4000 cm −1 ). Thus, the nitrosylated iron-sulfur clusters feature some exceptionally high J values relative to the nonnitrosylated {2Fe2S} and {4Fe4S} clusters. An analysis of spin-dependent bonding energies shed light on this curious feature. In essence, the energy difference between the high-spin (i.e., ferromagnetically coupled iron sites) and low-spin (i.e., maximum spin coupling) states of Roussin's salts are indeed rather similar to those of analogous non-nitrosylated iron-sulfur clusters. However, the individual Fe(NO) x (x=1, 2) site spins are lower in the nitrosylated systems, resulting in a smaller denominator in both the Noodleman and Yamaguchi formulas for J, which in turn translates into the very high J values.

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Section: Bond Length []/ Angle [8] [A]supporting

confidence: 64%

Section: Resultsmentioning

confidence: 99%

Section: Bond Length []/ Angle [8] [A]mentioning

confidence: 99%

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Spin Coupling in Roussin’s Red and Black Salts

Hopmann

Noodleman

Ghosh

2010

Chemistry A European J

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“…The calculated geometry of complex 8 is in rather good agreement with the experimental data ( Table 5). The geometry optimization of complex 8 with the 6 31G* basis set gave a structure with the C 2v symme try in contrast to the D 2h symmetry obtained in calcula tions with the LANL2DZ basis set, 76 is as low as 10 kcal mol -1 (or 5 kcal mol -1 , on the average, per N 2 O molecule). A change in the N-Fe-N angle in complex 8 is sufficient for the formation of an N-N bond.…”

Section: Elimination Of No and N 2 O From [Fe-s] Nitrosyl Complexesmentioning

confidence: 99%