Crystal and molecular structure of the complex boron triferrocenyl-pyridine

Soriano-Garcı́a, Manuel; Toscano, Rubén A.; López, T.; Campero-Celis, Antonio

doi:10.1007/bf01160736

Cited by 9 publications

(6 citation statements)

References 12 publications

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“…The B−N distances of 1.652(3) and 1.640(4) Å for trans - 5b and trans - 5c , respectively, are similar to one another and in the range of other B−N bond lengths reported for organoborane pyridine complexes (mean B−N distance from CSD search for R 3 B·Py: 1.650 Å). They are close to the B−N distances in related ferrocenylborane pyridine adducts such as Fc 3 B·Py (1.658 Å) and FcBMe 2 ·DMAP (1.670 Å). However, they are longer than for reported pyridine adducts of B(C 6 F 5 ) 3 such as B(C 6 F 5 ) 3 ·DMAP (1.604 Å).…”

Section: Resultssupporting

confidence: 59%

Examination of the Pyridine Binding to the Bifunctional Lewis Acid B,B′-Diphenyldiboradiferrocene

et al. 2008

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The binding behavior of the bifunctional Lewis acid (η 5 -C 5 H 5 Fe) 2 [µ-(C 5 H 3 (BPh)) 2 ] (3) toward different pyridine derivatives as the Lewis base has been investigated. The 1:1 and 1:2 adducts, 3 • D and 3 • D 2 (donor, D ) 4-tert-butylpyridine (tBupy) and 4-dimethylaminopyridine (DMAP)), were obtained by lowtemperature crystallization or slow solvent evaporation techniques. The complexes were fully characterized by multinuclear NMR, IR, and elemental analysis. Single-crystal X-ray diffraction data were collected for the 1:1 adduct with DMAP and for both 1:2 adducts, and the marked structural changes upon pyridine binding are discussed in detail. In solution, the 1:2 adducts were found to readily undergo dissociation with formation of the 1:1 adducts as the dominant species at room temperature. Variable-temperature NMR and UV-visible titration studies demonstrate that the first binding process is more than 5 orders of magnitude more favorable than the second binding process.

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Section: Resultssupporting

confidence: 59%

Examination of the Pyridine Binding to the Bifunctional Lewis Acid B,B′-Diphenyldiboradiferrocene

et al. 2008

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“…For example, the BN bonds in [FcBMe 2 ‐pyz‐Me 2 BFc] (BN 1.683(5) Å; pyz=pyrazine)6 are not much longer than that of 4 a , despite the fact that the former compound completely dissociates in solution already at ambient temperature. Another example is the triferrocenylborane adduct [Fc 3 Bpyridine], which is sterically more congested than 4 a and contains a weaker Lewis acid but nevertheless has a shorter BN bond of 1.658(4) Å 30…”

Section: Resultsmentioning

confidence: 99%

C₅H₄BR₂ Bending in Ferrocenylboranes: A Delocalized Through‐Space Interaction Between Iron and Boron

Scheibitz

Bolte

Bats

et al. 2004

Chemistry A European J

133

111

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A comparison of the molecular structures of mono-, di- and tetraborylated ferrocenes [Fc{B(R(1))(R(2))}] (R(1)/R(2)=Br/Br, Br/Fc, Br/Me, Me/Me, Me/OH, OMe/OMe), 1,1'-[fc{B(R(1))(R(2))}(2)] (R(1)/R(2)=Br/Br, Br/Me, OMe/OMe), and 1,1',3,3'-[Fe{C(5)H(3)(BMe(2))(2)}(2)] revealed the boryl substituent(s) to be bent out of the Cp ring plane towards the iron center. The corresponding dip angle alpha* decreases with decreasing Lewis acidity of the boron atom and with increasing degree of borylation at the ferrocene core. This trend is well reproduced by DFT calculations (including [FcBH(2)], not yet accessible experimentally). A Bader analysis of the electron density topology of [FcBH(2)] (alpha*=26.5 degrees ; BP86/TZVP) clearly showed that there is no direct iron-boron bonding in this compound. Instead, strongly delocalized orbital interactions have been identified that involve the boron p orbital, C(ipso) of the adjacent Cp ring, d orbitals at iron, and a through-space interaction with the second Cp ring. A second important factor is attractive electrostatic interactions, which are enhanced upon ligand bending. Cyclic voltammetric measurements on the series [FcBMe(2)], 1,1'-[fc(BMe(2))(2)], and 1,1',3,3'-[Fe{C(5)H(3)(BMe(2))(2)}(2)] indicate a substantial anodic shift in the oxidation potential of the central iron atom upon introduction of BMe(2) substituents. Addition of 4-dimethylaminopyridine (DMAP) does not just counterbalance this effect, but leads to a cathodic shift of the Fe(II)/Fe(III) redox transition far beyond the half-wave potential of parent ferrocene. In the Mossbauer spectra, a continuous decrease in the quadrupole splitting (QS) is observed upon going from parent ferrocene to [FcBMe(2)], to 1,1'-[fc(BMe(2))(2)], and to 1,1',3,3'-[Fe{C(5)H(3)(BMe(2))(2)}(2)]. In contrast, no significant differences are found between the QS values of ferrocene, [Fc(BMe(2)-DMAP)], and 1,1'-[fc(BMe(2)-DMAP)(2)].

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“…However, in most cases, even with bulky groups attached to the phenyl ring, fast isomerization of the enantiomers takes place via a two-ring flip mechanism with a fairly low acti vation barrier between 55 and 65 kJ/mol or less [1], In this context, triferrocenylborane, Fc3B (1), is of particular interest. The synthesis of 1 was de scribed previously [5], and the molecular structure of its pyridine adduct has been determ ined [6 ]. However, the structure of 1 has not been reported, and its NM R spectroscopic characterization in solution has remained incomplete.…”

mentioning

confidence: 99%

Triferrocenylborane – Molecular Structure in Solution and in the Solid State

Wrackmeyer

Dörfler

Milius

et al. 1995

Zeitschrift Für Naturforschung B

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Triarylboranes have received considerable at tention with respect to their conformation in solu tion and in the solid state as well as to the pro cesses of conform ational isomerization in solution [1][2][3]. Recently, it has been demonstrated that cer tain ethano-bridged triarylboranes can be resolved into their optically pure forms in solution at room tem perature [4]. However, in most cases, even with bulky groups attached to the phenyl ring, fast isomerization of the enantiomers takes place via a two-ring flip mechanism with a fairly low acti vation barrier between 55 and 65 kJ/mol or less [1], In this context, triferrocenylborane, Fc3B (1), is of particular interest. The synthesis of 1 was de scribed previously [5], and the molecular structure of its pyridine adduct has been determ ined [6 ]. However, the structure of 1 has not been reported, and its NM R spectroscopic characterization in solution has remained incomplete. We now report on the results of a single crystal X-ray analysis of 1 and on 13C NM R data of 1, measured at varia ble tem perature. Results and Discussion X -R ay analysisCrystals of Fc3B (1), suitable for X-ray analysis, were grown from toluene solutions. Experimental data of the X-ray analysis [7] are given in Table I, and the molecular structure of Fc3B is depicted in Fig. 1 together with selected bond lengths and bond angles. The arrangem ent of the molecules in the unit cell is shown in Fig. 2. The atomic coordi nates and therm al displacement param eters are Table I. Data of the X-ray analysis of Fc3B ( la ) a.

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Crystal and molecular structure of the complex boron triferrocenyl-pyridine

Cited by 9 publications

References 12 publications

Examination of the Pyridine Binding to the Bifunctional Lewis Acid B,B′-Diphenyldiboradiferrocene

Examination of the Pyridine Binding to the Bifunctional Lewis Acid B,B′-Diphenyldiboradiferrocene

C₅H₄BR₂ Bending in Ferrocenylboranes: A Delocalized Through‐Space Interaction Between Iron and Boron

Triferrocenylborane – Molecular Structure in Solution and in the Solid State

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Crystal and molecular structure of the complex boron triferrocenyl-pyridine

Cited by 9 publications

References 12 publications

Examination of the Pyridine Binding to the Bifunctional Lewis Acid B,B′-Diphenyldiboradiferrocene

Examination of the Pyridine Binding to the Bifunctional Lewis Acid B,B′-Diphenyldiboradiferrocene

C5H4BR2 Bending in Ferrocenylboranes: A Delocalized Through‐Space Interaction Between Iron and Boron

Triferrocenylborane – Molecular Structure in Solution and in the Solid State

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C₅H₄BR₂ Bending in Ferrocenylboranes: A Delocalized Through‐Space Interaction Between Iron and Boron