Organometallics
Article
Melchor, M.; Per
́
ez-Temprano, M. H.; Casares, J. A.; Ujaque, G.; de
(28) Thermolysis of 4 in the absence of added phosphine ligand
under otherwise identical conditions afforded full conversion of 4 and
́
Lera, A. R.; Alvarez, R.; Maseras, F.; Espinet, P. C-C reductive
elimination in palladium complexes, and the role of coupling
additives. A DFT study supported by experiment. J. Am. Chem. Soc.
1
9
55% PhCF
(29) Bakhmutov, Grushin, and Macgregor experimentally deter-
mined that (Xantphos)Pd(Ph)(CF ) undergoes reductive elimination
as determined by F NMR spectroscopy.
3
2
(
009, 131, 3650−3657.
12) For an experimental example comparing three-coordinate and
3
⧧
⧧
with ΔH = 25.9 kcal/mol and ΔS = 6.4 eu (see ref 15), suggesting
II
t
four-coordinate reductive elimination from Pd , see: Yamashita, M.;
Hartwig, J. F. Synthesis, structure, and reductive elimination
chemistry of three-coordinate arylpalladium amido complexes. J.
Am. Chem. Soc. 2004, 126, 5344−5345.
13) Zhang, S.-L.; Huang, L.; Sun, L.-J. The mechanism, electronic
and ligand effects for reductive elimination from arylPd(II)-
trifluoromethyl complexes: a systematic DFT study. Dalton Trans.
015, 44, 4613−4622.
14) Anstaett, P.; Schoenebeck, F. Reductive Elimination of ArCF3
that (D BPF)Pd(Ph)(CF
comparable activation parameters for reductive elimination.
30) Gaussian 09 was used at the M06 (ref 31) level for geometry
3
) and (Xantphos)Pd(Ph)(CF ) have
3
(
optimization. The Stuttgart/Dresden ECP (SDD) was used to
describe Pd and Fe (ref 32), and the 6-31G(d) basis set was used
for other atoms to form basis set BS1. All computation was carried out
for benzene as the solvent utilizing the IEFPCM (SCRF) model.
Single-point calculations were performed at the B3LYP-D3 level, as
recent studies indicate that the D3 calculation is suitable in
accounting for dispersion (ref 33), including for related palladium
phosphine systems (ref 34). These calculations employed the
quadrupole-ξ valence polarized def2-QZVP (ref 35) basis set on Pd
and Fe along with the corresponding ECP and the 6-311+G(2d,p)
basis set on other atoms (basis set BS2). All thermodynamic data
were calculated at the standard state (298.15 K and 1 atm). To
estimate the corresponding Gibbs free energies in benzene (ΔG),
entropy corrections were calculated at the M06/BS1 level and added
to the single-point potential energies. All transition structures
contained one imaginary frequency, exhibiting atom displacements
consistent with the anticipated reaction pathway. The nature of
transition structures was confirmed by intrinsic reaction coordinate
searches, vibrational frequency calculations, and potential energy
surface scans. Natural charge population analyses were performed in
conjunction with BS1 (ref 36).
(
2
(
II
from Bidentate Pd Complexes: A Computational Study. Chem. - Eur.
J. 2011, 17, 12340−12346.
(
15) Bakhmutov, V. I.; Bozoglian, F.; Gomez, K.; Gonzalez, G.;
́ ́
Grushin, V. V.; Macgregor, S. A.; Martin, E.; Miloserdov, F. M.;
Novikov, M. A.; Panetier, J. A.; Romashov, L. V. CF -Ph reductive
elimination from [(Xantphos)Pd(CF )(Ph)]. Organometallics 2012,
3
3
3
(
1, 1315−1328.
16) (a) Driver, M. S.; Hartwig, J. F. A second-generation catalyst
for aryl halide amination: mixed secondary amines from aryl halides
and primary amines catalyzed by (DPPF)PdCl . J. Am. Chem. Soc.
996, 118, 7217−7218. (b) Hamann, B. C.; Hartwig, J. F. Systematic
2
1
variation of bidentate ligands used in aryl halide amination.
Unexpected effects of steric, electronic, and geometric perturbations.
J. Am. Chem. Soc. 1998, 120, 3694−3703.
(
17) Mann, G.; Shelby, Q.; Roy, A. H.; Hartwig, J. F. Electronic and
(31) (a) Zhao, Y.; Schultz, N. E.; Truhlar, D. G. Design of density
steric effects on the reductive elimination of diaryl ethers from
palladium(II). Organometallics 2003, 22, 2775−2789.
18) This method has been used for the synthesis of (DPPF)
Pd (Ar)(CF H) complexes: Gu, Y.; Leng, X.; Shen, Q. Cooperative
dual palladium/silver catalyst for direct difluoromethylation of aryl
bromides and iodides. Nat. Commun. 2014, 5, 5405.
19) Spessard, G. O.; Miessler, G. L. Organometallic Reactions I:
Reactions That Occur at the Metal. Organometallic Chemistry, 2nd ed.;
Oxford University Press, Inc.: New York, 2010; pp 179−181.
20) This distortion was observed in a related complex (see ref 17)
and in (Xantphos)Pd (Ph)(CF ) (see ref 15).
21) Based on a search of the Cambridge Structural Database
CSD), version 5.39, updated August 2018. General citation: Groom,
C. R.; Bruno, I. J.; Lightfoot, M. P.; Ward, S. C. Acta Crystallogr., Sect.
B: Struct. Sci., Cryst. Eng. Mater. 2016, 72, 171−179.
22) (Xantphos)Pd (Ph)(CF ) displays similar fluxional behavior in
solution, see refs 5 and 15.
23) An alternative mechanism was proposed for the isomerization
of (Xantphos)Pd (Ph)(CF ) that does not involve phosphine
dissociation. Rather, the transition state adopts a “truncated trigonal
bipyramidal structure” in which the CF ligand is in an equatorial
plane with the phosphine ligands and the phenyl ligand in an axial
coordination site. See ref 15. However, due to the large size of D BPF
and the long Pd−P1 bond length (2.5639 Å) observed in the solid-
state structure of 4, we favor the ligand dissociation pathway as
described in Scheme 1.
24) The addition of phosphine to trap Pd products is common in
studies of reductive elimination from Pd centers. For an example, see
ref 17.
25) The major Pd species observed after the reductive elimination
with D BPF complex 4 was D BPF-ligated Pd species as identified by
P NMR, and no formation of Pd black was observed.
26) (Xantphos)Pd(Ph)(CF ) was found to afford PhCF in
quantitative yield after heating at 80 °C for 3 h; see refs 5 and 15.
functionals by combining the method of constraint satisfaction with
parameterization for thermochemistry, thermochemical, kinetics, and
noncovalent interactions. J. Chem. Theory Comput. 2006, 2, 364−382.
(b) Zhao, Y.; Truhlar, D. G. A new local density functional for main-
group thermochemistry, transition metal bonding, thermochemical
kinetics, and noncovalent interactions. J. Chem. Phys. 2006, 125,
(
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2
(
1
94101. (c) Zhao, Y.; Truhlar, D. G. Density functional for
spectroscopy: no long-range self-interaction error, good performance
for Rydberg and charge-transfer states, and better performance on
average than B3LYP for ground states. J. Phys. Chem. A 2006, 110,
13126−13130. (d) Zhao, Y.; Truhlar, D. G. Density functionals with
broad applicability in chemistry. Acc. Chem. Res. 2008, 41, 157−167.
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(
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(32) Andrae, H.; Haußermann, U.; Dolg, M.; Stoll, H.; Preuß, H.
̈
Energy-adjusted ab initio pseudopotentials for the second and third
row transition elements. Theor. Chim. Acta 1990, 77, 123−141.
(33) (a) Ehrlich, S.; Moellmann, J.; Grimme, S. Dispersion-corrected
density functional theory for aromatic interactions in complex
systems. Acc. Chem. Res. 2013, 46, 916−926. (b) Antony, J.; Sure,
R.; Grimme, S. Using dispersion-corrected density functional theory
to understand supramolecular binding thermodynamics. Chem.
Commun. 2015, 51, 1764−1774.
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(
3
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3
3
(34) Lyngvi, E.; Sanhueza, I. A.; Schoenebeck, F. Dispersion makes
t
the difference: bisligated transition states found for the oxidative
addition of Pd(PtBu3) to Ar-OSO R and dispersion-controlled
2
2
chemoselectivity in reactions with Pd[P(iPr)(tBu)2)2. Organometallics
2
015, 34, 805−812.
0
(35) Weigend, F.; Furche, F.; Ahlrichs, R. Gaussian basis sets of
(
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quadruple zeta valence quality for atoms H-Kr. J. Chem. Phys. 2003,
1
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19, 12753−12762.
36) Glendening, E. D.; Read, A. E.; Carpenter, J. E.; Weinhold, F.
(
t
t
0
NBO, version 3.1; Gaussian Inc.: Pittsburgh, PA, 2003.
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(37) Leclerc, M. C.; Bayne, J. M.; Lee, G. M.; Gorelsky, S. I.; Vasiliu,
M.; Korobkov, I.; Harrison, D. J.; Dixon, D. A.; Baker, R. T.
Perfluoroalkyl cobalt(III) fluoride and bis(perfluoroalkyl) complexes:
catalytic fluorination and selective difluorocarbene formation. J. Am.
Chem. Soc. 2015, 137, 16064−16073.
(
3
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that the large size of D BPF may hinder transmetalation in this
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(
38) Heating 3 for 24 h under analogous conditions afforded PhCF3
t
in 58% yield with 69% conversion of 3.
catalytic system.
H
Organometallics XXXX, XXX, XXX−XXX