Synthesis, structure, and reductive elimination in the series Tp′Rh(PR3)(ArF)H; Determination of rhodium-carbon bond energies of fluoroaryl substituents

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Synthesis, structure, and reductive elimination in the series

Tp¢Rh(PR₃)(Ar^F)H; Determination of rhodium–carbon bond energies

of ﬂuoroaryl substituents†‡

Taro Tanabe,^aWilliam W. Brennessel,^aEric Clot,^bOdile Eisenstein^band William D. Jones*^a

Received 17th March 2010, Accepted 8th June 2010

DOI: 10.1039/c0dt00157k

A series of complexes of the type Tp¢Rh(PR₃)(Ar^F)H, where PR₃= PMe₃(3) and PMe₂Ph (9), Ar^F=

C₆F₅(a), 2,3,4,5-C₆F₄H (b), 2,3,5,6-C₆F₄H (c), 2,4,6-C₆F₃H₂(d), 2,3-C₆F₂H₃(e), 2,5-C₆F₂H₃(g), and

2-C₆FH₄(h) and Tp¢ = tris(3,5-dimethylpyrazolyl)borate, has been synthesized as stable crystalline

compounds by the reactions of the [Tp¢Rh(PR₃)] fragment with the corresponding ﬂuorinated aromatic

hydrocarbons, and their structures were characterized by NMR spectroscopy and elemental analysis

together with X-ray crystallography. The kinetics of the reductive eliminations of ﬂuoroarenes from

complexes 3a–h in benzene-d₆solutions at 140 ^◦C were investigated, but were complicated by the

formation of the rhodium(I) bisphosphine complex, Tp¢Rh(PMe₃)₂(4). On the other hand, thermal

reactions of (9) in THF-d₈solutions at 120 ^◦C resulted in the formation of an intramolecular C–H bond

2

activated complex of the phenyl group on the phosphorus atom, Tp¢Rh(k -C₆H₄-2-PMe₂)H (7), which

prevents the formation of the corresponding bisphosphine complex. The experimentally determined

rates of the reductive eliminations of ﬂuoroarenes from the complexes 9a–h and their kinetic

selectivities for formation in competition with the metallacycle have been used to determine relative

Rh–CAr^Fbond energies. The Rh–CAr^Fbond energy is found to be dependent on the number of ortho

ﬂuorines. A plot of Rh–CAr^Fvs. C–H bond strengths resulted in a line with a slope R^M–C/C–Hof 2.15 that

closely matches the DFT calculated value (slope = 2.05).

[Tp¢Rh(CO)]⁵or [Tp¢Rh(CNCH₂CMe₃)]⁶(Cp* = C₅Me₅, Tp¢ =

Introduction

tris(3,5-dimethylpyrazolyl)borate), generated by the photolysis

2

The activation and functionalization of C–H bonds of hydrocar-

of Cp*Rh(PMe₃)H₂, Tp¢Rh(CO)₂or Tp¢Rh(CNCH₂CMe₃)(h -

bons for industrial and synthetic processes utilizing homogeneous

= =

PhN C NCH₂CMe₃) respectively, have been well studied mech-

anistically in detail.^1,7

transition metal catalysts has been one of the most attractive

subjects in organometallic chemistry, and has been widely studied

from the viewpoint of not only fundamental chemistry but also

their application towards organic synthesis and material science.¹

To understand the kinetic and thermodynamic selectivity of C–

H bond activation, several useful transition metal systems have

been developed which are capable of activation of aromatic and

aliphatic C–H bonds in homogeneous solution.^1–7

Some of these transition metal complexes contain metals

in high oxidation states and act through an electrophilic s-

metathesis pathway,²while others are in low oxidation states

and react by oxidative addition of the C–H bond.³Focusing

on rhodium metal systems of the latter variety, the 16 electron

coordinatively unsaturated metal fragments [Cp*Rh(PMe₃)],⁴

In the past few decades, much attention has been focused on

correlations between metal–carbon and carbon–hydrogen bond

strengths by utilizing such transition metal systems, and only a

limited number of experimental correlations have been reported

so far.^6,8–14On the other hand, remarkable progress has been

made in the catalytic C–H bond activation of benzene derivatives,

especially by borylation¹⁵or by direct arylation.¹⁶A wide range of

functionalized benzene derivatives has also been investigated in the

past decade, including ﬂuorinated aromatic hydrocarbons,¹⁷which

offer the possibility for both C–H and C–F bond activation.¹⁸

Perutz et al. have found that [Cp*Re(CO)₂] was capable of C–H

bond activation of partially ﬂuorinated aromatic hydrocarbons,¹⁹

while previously reported nickel complexes, such as [Ni(PEt₃)₂],

[Ni(dtbpe)] or [Ni((i-Pr)₂Im)₂] (dtbpe = (t-Bu)₂PCH₂CH₂P(t-Bu)₂,

(i-Pr)₂Im = 1,3-di(isopropyl)imidazol-2-ylidene), were found to

be favorable to C–F bond activation.²⁰They demonstrated the

relationship between M–C and C–H bond energies and revealed

that ortho ﬂuorine substitution produces a much larger increase

in the M–C over the C–H bond energy, both by theoretical and

experimental approaches.^19,21Furthermore, Perutz and Eisenstein

et al. reported exciting results that the number of ortho ﬂuorine

substituents strongly affected the M–C bond strength while

the total number of ﬂuorine substituents only had a minor

effect on the M–C bond strength.^21,22Complexes with two ortho

ﬂuorines had calculated M–C bond strengths ~5 kcal mol^-1higher

^aDepartment of Chemistry, University of Rochester, Rochester, New York,

14627, USA. E-mail: jones@chem.rochester.edu

^bInstitut Charles Gerhardt, Universite´ Montpellier 2, CNRS 5253, case

courrier 1501, Place E., Bataillon, 34095, Montpellier, France

† Based on the presentation given at Dalton Discussion No. 12, 13–15th

September 2010, Durham University, UK.

‡ Electronic supplementary information (ESI) available: Detailed results

of the kinetics of the reductive eliminations, coordinates and energies for

calculated complexes, a summary of the calculation procedure, the full

list of authors for reference 38, and summaries of structural reﬁnements.

CCDC reference numbers for 1, 2-d₆, 3a, 3b, 3d, 3g, Tp¢RhCl₂(PPhMe₂), 5,

7, 9a, 9b, 9c, 9d, 9e and 9g: 770109–770123. For ESI and crystallographic

data in CIF or other electronic format see DOI: 10.1039/c0dt00157k

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The Royal Society of Chemistry 2010

Dalton Trans., 2010, 39, 10495–10509 | 10495

©

than complexes with one ortho ﬂuorine in the aryl ligand of

Cp*Re(CO)₂Ar^FH.

Very recently, we have also independently reported the experi-

mental and theoretical correlation of the Rh–C bond strength

of ﬂuoroaryls, using the system Tp¢Rh(CNCH₂CMe₃)(Ar^F)H.

The M–C bond strength is also strongly dependent on the number

of ortho ﬂuorine substituents and only mildly dependent on the

total number of ﬂuorine substituents on the phenyl ring.²³Com-

plexes with aryl groups containing two ortho ﬂuorine substituents

have barriers to reductive elimination that are ~5 kcal mol^-1higher

than those for a single ortho ﬂuorine substituent.²³Furthermore,

the relationship between Rh–C_Arand C–H bond strengths for a

series of these complexes has been found to be linear (slope =

2.14), and closely matched the theoretically calculated value

(slope = 1.96).²³Complexes bearing electron withdrawing (p

accepting character) ligands, such as CO and RNC, have been

used in these systems. Eisenstein et al. have reported theoretical

results²²that indicate that the change in the nature of the

spectator ligands affects the value of the slope R^M–C/C–Hand

their selectivities. We have prepared a series of stable crystalline

compounds Tp¢Rh(PR₃)(Ar^F)H (PR₃= PMe₃(3) and PPhMe₂

(9); Ar^F= C₆F₅(a), 2,3,4,5-C₆F₄H (b), 2,3,5,6-C₆F₄H (c), 2,4,6-

C₆F₃H₂(d), 2,3-C₆F₂H₃(e), 2,5-C₆F₂H₃(g), and 2-C₆FH₄(h)) by

the reactions of a [Tp¢Rh(PR₃)] fragment with ﬂuorinated benzene

derivatives, and their structures were characterized by NMR

spectroscopy together with X-ray crystallography. Experimental

results employing kinetic techniques have been used to relate the

Rh–CAr^Fvs. C–H bond strengths, and the relative free energies of

these phosphine coordinated complexes will be described.

Fig. 1 X-ray structure of 1 (thermal elipsoids at 50% probability level).

Hydrogen atoms except for RhH₂were omitted for clarity.

lamp that had been ﬁltered using a 270–370 nm band pass ﬁlter.

Similarly, C–H bond activated products of the ﬂuorobenzenes,

Tp¢Rh(PMe₃)(Ar^F)H (3a–h), have been synthesized and isolated

as stable crystalline compounds by the irradiation of 1 in the

corresponding ﬂuorobenzene solution as shown in Scheme 2.

Only a single isomer of the ﬂuorobenzene activated product was

obtained in the synthesis of 3a–d and 3g. On the other hand, in

the synthesis of 3e (1,2-diﬂuorobenzene), 3f (1,3-diﬂuorobenzene),

and 3h (ﬂuorobenzene), two or three isomers were obtained upon

irradiation.

Results and discussion

Synthesis of Tp¢Rh(PMe₃)Ar^FH (3)

The rhodium dihydride complex bearing Tp¢ and trimethyl-

phosphine ligands, Tp¢RhH₂(PMe₃) 1, is known to be an excellent

precursor of rhodium(I) fragment [Tp¢Rh(PMe₃)] under near-UV

irradiation. Although Carmona et al.,²⁴and more recently our

group²⁵have reported the synthesis and spectroscopic data of 1,

there have been no reports on its crystal structure (Scheme 1).

Recrystallization of 1 from hexane afforded colorless crystals and

the molecular structure was revealed by X-ray structural analysis

(Fig. 1). A slightly distorted octahedral geometry around the

rhodium metal center was observed. The rhodium–nitrogen (for

˚

Tp¢) bond lengths (2.2193(13), 2.1124(11) and 2.2076(12) A) are

slightly longer than those of the corresponding rhodium dichloride

26

˚

derivative (2.151(2), 2.087(2) and 2.145(2) A).

Scheme 1 Synthesis of rhodium dihydride 1.

Complete conversion of 1 to Tp¢Rh(PMe₃)(C₆H(D)₅)H(D) (2

or 2-d₆) was accomplished by photolysis of 1 (l = 304 nm,

e = 165 cm^-1M^-1) in C₆H₆or C₆D₆with light from a Hg/Xe

Scheme 2 Synthesis of C–H bond activated products of ﬂuorinated

benzene derivatives 3 by using 1.

10496 | Dalton Trans., 2010, 39, 10495–10509

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Fig. 2 X-ray structures of 2-d₆, 3a, 3b, and 3g (thermal ellipsoids at 50% probability level). Hydrogen atoms except for RhH(D) were omitted for clarity.

◦

Heating of these crude mixtures containing isomers at 100 C

resulted in the conversion to the thermodynamically preferred

products, 3e and 3h. However, isolation of 3f was unsuccessful

inductive effect, a longer Rh–Ar bond length, and wide ∠P–

Rh–Ar bond angles were observed in the crystal structure of _◦3a

◦

˚

(2.046(7) A, 96.8(2) ) compared to 2-d₆(2.0171(15) A, 91.06(4) ),

◦

˚

even following heating at 100 C for three months, as a mixture

3b (2.030(5) A, 93.88(14) ), and 3g (2.013(4) A, 92.88(11) ). The

slightly shorter Rh–Ar bond length in 3g compared to 2-d₆can

be explained by the inductive effect of ﬂuorine atoms. However, it

should be noted that the steric repulsion around the rhodium has

a more pronounced inﬂuence on the Rh–Ar^Fbond lengths over

the inductive effects of the ﬂuorines.

of the 2,6-diﬂuorophenyl- (3f), 2,4-diﬂuorophenyl-, and 3,5-

diﬂuorophenyl- substituted complexes remained. The molecular

structures of these newly isolated complexes were characterized by

1

¹H, ¹³C{ H}, ¹⁹F{ H} and ³¹P{ H} NMR spectroscopy together

with elemental analysis. In all cases, a signal for the hydride

was observed as a doublet of doublet of doublets or a doublet

of triplets between d -15 and -17 ppm. Both H and ¹⁹F{ H}

NMR spectra indicated hindered rotation around the rhodium–

carbon(aryl) bond. For example, ﬁve inequivalent signals were

1

Reductive elimination of ﬂuoroarenes from 3

Reductive elimination of C₆H₆from 2 in C₆D₆at 100 ^◦C has

been previously reported, and follows ﬁrst order kinetics with

a rate constant of 8.3(1.2) ¥ 10^-5s^-1.²⁵The electron donating

phosphine ligand is expected to stabilize the rhodium(III) phenyl

hydride better than an electron withdrawing ligand such as CO

or RNC. However, the rate constant for reductive elimination of

C₆H_◦₆from the complex Tp¢Rh(CNCH₂CMe₃)(Ph)H in C₆D₆at

100 C has been determined (5.4(2) ¥ 10^-5s^-1),⁶which is slightly

smaller than that of 2. Rate constants for the reductive elimination

of ﬂuoroarenes from 3 (Scheme 3) were obtained in a similar way,

but higher temperatures were required as compared to 2 (C₆D₆

observed in the case of 3a in the ¹⁹F{ H} NMR spectrum. The

1

molecular structures of the complexes, 2-d₆, 3a, 3b, and 3g were

determined by X-ray crystallographic analysis (Fig. 2a–d).

In each case, similar structures were observed around the

rhodium metal center showing a slightly distorted octahedral

geometry. The (ﬂuoro)aryl groups interdigitate with the pyra-

zolylborate groups, with the plane of the aryl group containing the

three fold Rh–B axis. In the structures of 3a, 3b and 3g, one of the

ortho ﬂuorine atoms is in close proximity to the hydride suggesting

the possibility for coupling to the hydride in these cases.²³Despite

the fact that ortho ﬂuorine substituent(s) on the phenyl group

are known to strengthen metal–carbon(aryl) bonds due to their

◦

at 140 C in a sealed NMR tube). A plot of ln([C]_t/[C]₀) of the

ﬂuoroarene activated complex vs. time was used to determine the

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©

Fig. 3 X-ray structure of 5 (thermal ellipsoids at 50% probability level).

Hydrogen atoms except for RhH₂were omitted for clarity.

Scheme 3 Reductive eliminations of ﬂuoroarenes from 3 in C₆D₆.

˚

seen in 1, and the rhodium–phosphorus bond length (2.2218(6) A)

showed a slightly longer value than that of 1 (2.2178(5) A).

˚

rates of the reductive eliminations. However, in all cases, a fast

decrease of the integrations for hydride of 3 and the formation of

rhodium(I) bisphosphine complex Tp¢Rh(PMe₃)₂(4, d_P= -2.2,

¹J_RhP= 171 Hz) was observed during the reactions. Observation

of a doublet signal bearing a larger value of ¹J_RhPunambiguously

indicated the formation of 4.²⁷The formation of 4 prevented deter-

mination of the kinetic parameters for the reductive eliminations

because the second trimethylphosphine ligand in the bisphosphine

complex 4 came from decomposition of starting material 3 or

product 2-d₆. Thermal reactions of 2-d₆in C₆D₆were examined

at 140, 120 and 100 ^◦C. Formation of bisphosphine complex 4

was observed above 120 ^◦C. Although thermal reaction at 100 ^◦C

suggested the possibility of determining the kinetic parameters for

the reductive eliminations of complexes 3, it would take too long

(months) to determine the rates for the pentaﬂuoro (3a) or 2,3,5,6-

tetraﬂuoro (3c) systems bearing strong Rh–Ar^Fbonds. To prevent

the formation of bisphosphine complex, the thermal reactions of

2-d₆in the presence of Et₃SiH or MeOH as trapping reagents for

the rhodium(I) species [Tp¢Rh(PMe₃)] were investigated. However,

the formation of 4 was still observed even with these additives.

These reactions afforded rhodium dihydride 1 together with 4 and

an unknown species, indicating that the PMe₃complexes are not

well suited to kinetic investigations.

The benzene-d₆activated product Tp¢Rh(C₆D₅)D(PPhMe₂) 6-

d₆was prepared by the irradiation of 5 in C₆D₆in 64% isolated

yield. Then thermal reaction of 6-d₆in C₆D₆was examined

at 120 ^◦C. Reaction for 3 h afforded the four-membered-ring

rhodacycle, which possesses an intramolecular orthometallated

2

C–H bond activated phenyl group, Tp¢Rh(k -C₆H₄-2-PMe₂)H (7).

1

7 forms in about 25% yield as judged by H NMR spectroscopy

(Scheme 4). No change of the ratio of 7 to 6-d₆(1 : 3) was observed

with heating at 120 ^◦C for 1 day or more. It should be noted

that less than 1% of the corresponding bisphosphine complex,

Tp¢Rh(PhMe₂)₂8, was observed.²⁷No other species except for

1

7 and 6-d₆could be detected in the H NMR spectrum during

the reaction. Furthermore, these results suggested an equilibrium

between 7 and 6-d₆in C₆D₆. Changing the solvent for this mixture

from C₆D₆to THF followed by the heating at 120 ^◦C for 1 h

resulted in the quantitative conversion to 7, which was isolated in

84% yield (Scheme 4) and characterized by NMR spectroscopy

together with elemental analysis. Observation of four protons

1

assignable to the phenyl ring in the aromatic region of the H

Intramolecular C–H bond activation of [Tp¢Rh(PPhMe₂)]

Because of the undesirable formation of 4, a change in the

phosphine ligand of the starting material was required for further

kinetic investigations. Our second choice of phosphine ligand was

dimethylphenylphosphine, for two reasons: (1) to decrease the

s-donating character (minor change); (2) to introduce reactive

ortho C–H bonds of the phenyl group on the phosphorus atom to

trap the rhodium(I) metal center. Although triphenylphosphine

was also considered for prevention of the formation of the

bisphosphine complex, it has substantial p-accepting character

together with weak s-donating character. Instead, the rhodium

dihydride bearing dimethylphenylphosphine, Tp¢RhH₂(PPhMe₂)

5,²⁴was prepared by the same method used for 1 with a

similar yield. The molecular structure of 5 was revealed by X-

ray crystallography (Fig. 3). The rhodium–nitrogen bond lengths

˚

(2.2341(18), 2.1036(18) and 2.1863(18) A) were similar to those

Scheme 4 Synthesis and thermal reactions of 6-d₆.

10498 | Dalton Trans., 2010, 39, 10495–10509

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NMR spectrum and a high ﬁeld ³¹P shift compared with that

of 6-d₆(7: d_P= -65.12; 6-d₆d_P= 15.35) strongly suggested the

cyclometallated structure of 7.²⁸The molecular structure of 7 was

unambiguously determined by X-ray structural analysis (Fig. 4).

Fig. 4 X-ray structure of 7 (thermal ellipsoid plot with 50% probability

level). Hydrogen atoms except for RhH were omitted for clarity.

Scheme 5 Synthesis of C–H bond activated products of ﬂuorinated

benzene derivatives 9 by utilizing 5

The results shown in Scheme 4 suggested that it would be

possible to measure the rates for the reductive eliminations of

ﬂuoroarenes in these complexes without any additional trapping

reagents (the Rh(I) species traps itself by cyclometallation). Al-

though conversion of Rh(I) to the four-membered-ring rhodacycle

7 should be reversible (equilibrium), fast intramolecular C–H

insertion was found to prevent the formation of bisphosphine

complex 8.

Synthesis and kinetic selectivities of Tp¢Rh(PhMe₂)Ar^FH (9)

The isolated yield of 6-d₆(64%) is signiﬁcantly lower than that

of 2-d₆(99%). In the synthesis of 6-d₆, intramolecular C–H bond

activated product 7 was also obtained after the photo-irradiation

(6-d₆: 7 = 6.7 : 1.0). Heating the C₆D₆solution of the crude mixture

followed by puriﬁcation afforded 6-d₆in pure form. Employing

similar reactions as for 3a–h, the C–H bond activated products

Tp¢Rh(PhMe₂)(Ar^F)H (9a–h) have been synthesized and isolated

as stable crystalline compounds as shown in Scheme 5. As before,

it should be noted that heating in the corresponding ﬂuoroarene

solvent after the irradiation is necessary to obtain the products in

good yields because of the kinetically competitive formation of 7.

Fig. 5 Free energy diagram for activation of hydrocarbon C–H bonds

with [Tp¢Rh(PPhMe₂)].

DG^◦= DG_re(7) - DDG_oa(Ar^FH) - DG_re(9 or 6)

DDG_oa(Ar^FH) = RT ln([9 or 6]/[7])

(1)

(2)

Scheme 6 shows the kinetic selectivities as the ratio of 9a–g

(or 6) to 7 just after irradiation. In these six systems, a single

isomer of the ﬂuorobenzene (or benzene) activated product was

obtained after the photolysis. In the synthesis of 9a and 9b, the

ratio of 9 to 7 was almost 1 : 2 in the pentaﬂuoro system (9a), while

the ratio was 2 : 1 in the 1,2,3,4-tetraﬂuoro system (9b). On the

other hand, both 9c and 9d were formed in almost equal amounts

compared to 7. 9g and 6 showed the largest selectivities relative to

7. Scheme 7 shows the ratio of 9e or 9h vs. 7 in the reactions with

1,2-diﬂuorobenzene or ﬂuorobenzene. These systems afforded two

or three isomers with kinetic selectivities comparable to the other

mono ortho-ﬂuoro aryl products. The mild selectivities result in

small values for DDG^‡_oa(Ar^FH), in which the largest difference

1

These complexes were characterized by ¹H, ¹³C{ H}, ³¹P{ H} and

1

¹⁹F{ H} NMR spectroscopy together with elemental analysis.

The relative free energy values (DG^◦) for the ﬂuorobenzene

oxidative addition products 9 can be determined by analysis of

the kinetics for ﬂuoroarene reductive elimination (DG^‡_re) together

with the kinetic selectivities (DDG^‡_oa(Ar^FH)) according to eqn

1. The kinetic selectivities (DDG^‡_oa(Ar^FH)) of the ﬂuorobenzene

activated product 9 and cyclometallated product 7 can be directly

estimated based on the ratio with intramolecular C–H bond

activated product 7 just after irradiation as measured by ¹H NMR

spectroscopy, as shown in Schemes 6 and 7, eqn 2, and graphically

in Fig. 5. Basically, DDG^‡_oa(Ar^FH) in this system are shown as the

kinetic selectivities for each (ﬂuoro)benzene activated compound

6 or 9 as compared with that of cyclometallated compound 7.

observed was between 9a (DDG^‡= -0.40 kcal mol^-1) and 6

oa

(DDG^‡= +1.12 kcal mol^-1).

oa

The molecular structures of these newly isolated complexes,

9a, 9b, 9c, 9d, 9e and 9g, were unambiguously revealed by

X-ray crystallographic analysis. Similar to the complexes 3 bearing

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©

¹J rhodium–phosphorus coupling constant of 7 (114 Hz) in the

1

³¹P{ H} NMR spectrum was much smaller than those of 9 (132–

136 Hz) by almost 20 Hz. However, the rhodium–phosphorus

˚

bond length of 7 (2.2468(15) A) was shorter than those of 9 (9a:

˚

2.2777(3) A; 9b: 2.2649(4) A; 9c: 2.2643(5) A; 9d: 2.2688(4) A; 9e:

˚

2.2545(10) A; 9g: 2.2681(5) A).

Reductive eliminations of ﬂuoroarenes from 9

The rates of reductive elimination of ﬂuoroarenes from complexes

9a–e, 9g–h, and 6 were determined at 120 ^◦C in THF-d₈by

1

monitoring the conversion of the complexes to 7 by H NMR

spectroscopy (Scheme 8). Kinetic analysis was performed by

integration of the decreasing hydride resonance relative to an

1

internal standard by H NMR spectroscopy. A ﬁrst order plot

of the decay of the concentration of 9 or 6 vs. time showed upward

curvature, as the reactions did not go to completion but rather

approached equilibrium (71–98% complete). Therefore, the rate

of Ar^FH reductive elimination (k₁) from 9 was determined by a

kinetic simulation of eqn 3 using the KINSIM/FITSIM software

package (see Supporting Information for details‡).²⁹

Scheme 6 The ratio of the ﬂuoroarene activated product based on 7 after

photo-irradiation in the synthesis of 9a–d, 9g and 6.

k1

ꢀꢀꢀꢀꢁ

ꢂꢀꢀꢀ

(3)

9

7

k − 1

Scheme 8 Kinetics of the reductive elimination of ﬂuoroarenes from the

complexes 9 and 6 at in THF-d₈.

Scheme 7 The ratio of the ﬂuoroarene activated product based on 7 after

photo-irradiation in the synthesis of 9e and 9h.

Kinetics for the complexes 9b, 9c, 9d, 9e, 9g and 9h were

successfully simulated using this approach to an equilibrium

model. For the pentaﬂuorobenzene activated product 9a, however,

a plot of ln[9a] vs. time showed downward curvature, which was

attributed to slow decomposition of 7 during the long reaction

a PMe₃ligand, slightly distorted octahedral geometries around

the rhodium metal center are also observed in these complexes

(Fig. 6a–f). It should be noted that the phenyl group on the

phosphorus atom is oriented away from the rhodium metal center

time (t ₂ª 4 months @ 120 ^◦C). As a result, the rate of reductive

1

in these complexes. As observed in the PMe₃system, the observed

F

˚

length of the Rh–Ar bond of 9a (2.0400(10) A) was longer than

elimination af C₆F₅H from 9a was estimated using initial rate data

only (see Supporting Information‡). The rate constant reported

for 9a should therefore be considered as an upper limit and the

relative free energy DG^◦as a lower limit (vide infra). In contrast,

the reductive elimination of benzene in 6 at 120 ^◦C was too fast to

monitor by NMR spectroscopy. Therefore, this rate constant was

extrapolated from an Eyring plot using rate data recorded at 60,

70, 80, and 90 ^◦C (DH^π= 37.4 3.5 kcal mol^-1; DS^π= 27 10 e.u.,

see Supporting Information‡).

˚

those in 9b (2.0228(11) A), 9e (2.028(4) A) and 9g (2.0329(16) A)

(bearing one ortho ﬂuorine) because of steric repulsion, and very

˚

similar to those of 9c (2.0388(17) A) and 9d (2.0446(13) A)

(bearing two ortho ﬂuorines). The steric repulsion around the

rhodium still has a critical inﬂuence on the rhodium–carbon bond

lengths as does the inductive effects of ﬂuorine substituents in

the structures. As with the PMe₃complexes, some of the aryl

carbons in compounds 9 could not be observed in their ¹³C{ H}

1

NMR spectra because of the multiple couplings with many of the

ﬂuorines in the aryl group.

Table 1 summarizes the experimental results of the kinetics of

reductive elimination of ﬂuoroarenes from 9a–e, 9g–h, and 6,

showing rate constant k_re(Ar^FH) along with the corresponding

DG^πactivation energies. As expected, the observed DG^πof 9a

The structural features of 9 can be compared with those of

intramolecular C–H bond activated product 7. The Rh–Ar^Fbond

re

˚

lengths of 9 were slightly longer than that of 7 (2.022(5) A),

was largest, consistent with a strong Rh–Ar^Fbond. Focussing on

probably because of the steric repulsion in 9 that is absent in 7. The

the comparison of 9b and 9d in this system, the ortho ﬂuorine effect

10500 | Dalton Trans., 2010, 39, 10495–10509

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Fig. 6 X-ray structures of 9a, 9b, 9c, 9d, 9e, and 9g (a–f, thermal ellipsoids at 50% probability level). Hydrogen atoms except for RhH were omitted for

clarity.

indicated in Fig. 5, the relative free energy value DG^◦for the

complexes, 9a–e, 9g–h, and 6, can be determined using eqn 1.

Furthermore, using the experimentally determined DG^◦values

along with calculated C–H bond strengths for each of the

ﬂuoroarenes, the relative Rh–Ar^Fbond strengths in complexes

9 can be determined according to eqn 4, which includes the

assumption that DG^◦ª DH^◦- RT ln(H₉/H₇), where H₉/H₇is

the ratio of the number of hydrogens that can be activated on

the ﬂuoroarene substrate divided by the number of hydrogens

available for activation in 7 (= 2H); i.e., the DS^◦values are the

same for these reactions,⁶other than the statistical contribution

for the number of hydrogens. Since these experiments measure

DG^◦, whereas bond strengths are reﬂected by DH^◦, a correction

for DS^◦must be included.

Table 1 Rates of reductive elimination of Ar^FH from Tp¢Rh(PPhMe₂)-

Ar^FH at 120 ^◦C

Complex

Ar^F

k_re(Ar^FH)/s^-1

DG^π_re/kcal mol^-1

9a

9b

9c

9d

9e

9g

9h

6^a

C₆F₅

7.04(0.61) ¥ 10^-8

9.86(0.69) ¥ 10^-7

1.79(0.05) ¥10^-7

8.93(0.13) ¥ l0^-6

5.85(0.13) ¥ 10^-5

3.05(0.06) ¥ 10^-5

2.50(0.02) ¥ 10^-4

1.22(0.70) ¥ 10^-2

36.09(0.07)

34.03(0.05)

35.37(0.02)

32.31(0.01)

30.84(0.02)

31.35(0.02)

29.71(0.01)

26.67(0.45)

2,3,4,5-C₆F₄H

2,3,5,6-C₆F₄H

2,4,6-C₆F₃H₂

2,3-C₆F₂H₃

2,5-C₆F₂H₃

2-C₆FH₄

C₆H₅

^aThe rate of the reaction was measured at various lower temperatures, 60,

70, 80, and 90 ^◦C, and the reaction rate at 120 ^◦C estimated by the EYRING

plot of ln(k/T) vs. 1/T. Errors are reported as standard deviations.

D_rel(Rh–Ar^F) = [DH(Rh–Ar^F) - DH(Rh–Ar⁷)] = DG^◦- RT

also has critical but not sole inﬂuence on DG^π_re. For example, the

ln(H₉/H₇) - [D(Ar^F–H) - D(Ar⁷–H)]

(4)

DG^πfor 9d (total #F = 3, ortho #F = 2) is lower than that of 9b

re

(total #F = 4, ortho #F = 1), but it is still much higher than those

of the diﬂuoro species 9e or 9g (total #F = 2, ortho #F = 1).

Table 2 summarizes the kinetic and thermodynamic data for

formation of Tp¢Rh(Ar^F)H(PPhMe₂). The Rh–Ar^Fbond strengths

have been adjusted to be relative to that of the phenyl hydride

complex, 6 (which is set to 0 kcal mol^-1), rather than to metallacycle

7. For comparison, DFT was used to calculate Rh–Ar^Fbond

strengths as done previously (see Supporting Information for

details‡).³⁰As can be seen, the trend in the experimental data for

D(Rh–Ar^F)_relvs. D(Ar^F–H) is in excellent agreement with the trend

Thermodynamics for ﬂuoroarene C–H bond activation by

[Tp¢Rh(PPhMe₂)]: Relative Rh–C_Arvs. C–H bond strength

The thermodynamics for the ﬂuoroarene C–H bond activation

by [Tp¢Rh(PPhMe₂)] were determined by using the results from

the reductive elimination and kinetic selectivity experiments. As

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©

Table 2 Kinetic and thermodynamic data for formation of Tp¢Rh(PPhMe₂)Ar^FH (kcal mol^-1)

DG^◦

Calcd ^cD(Ar^F–H)

Exptl^{b d}D(Rh–Ar^F)_rel

Calcd^{bd e}D(Rh–Ar^F)_rel

πa

π

b

DDG_oa

DG_re

9a

9b

9c

9d

9e

9g

9h

6

-0.40

+0.41

-0.10

+0.02

+0.67

+0.61

+0.52

+1.12

36.09

34.03

35.37

32.31

30.84

31.35

29.71

26.67

-7.91

-6.65

-7.48

-4.55

-3.72

-4.17

-2.44

0.00

123.0

120.6

122.5

123.2

119.6

119.8

119.6

117.1

14.09

10.8

13.5

11.1

6.9

7.1

5.6

14.4

10.3

13.7

11.8

8.2

8.3

7.0

0.0

^aRelative to metallacycle (7). ^bRelative to phenyl hydride complex. ^cData from Ref. 22. ^dDH Corrected for number of hydrogens available for activation.

^ecalculated for the complexes, Tp¢Rh(Pme₃)Ar^FH.

of calculated D(Rh–Ar^F)_relvs. D(Ar^F–H) for the complexes. The

pentaﬂuorobenzene activated product, 9a, has the strongest Rh–

Ar^Fbond. The bond strengths in complexes containing two ortho

ﬂuorines exceed that in 6 by an average of about 13 kcal mol^-1.

The bond strengths in complexes containing one ortho ﬂuorine

exceed that in 6 by an average of about 5 kcal mol^-1. As observed

earlier in the system Tp¢Rh(Ar^F)H(CNneopentyl)²³bearing the

electron withdrawing isonitrile ligand as a spectator ligand, the

Rh–Ar^Fbond strength is still strongly dependent on the number

of ortho ﬂuorines and only mildly dependent on the total number

of ﬂuorines on the phenyl ring in this system. It is interesting to

compare bond strengths in the 1,2,3,4-tetraﬂuorobenzene (9b, one

ortho ﬂuorine) and 1,3,5-triﬂuorobenzene (9d, two ortho ﬂuorines)

activated complexes. In the phosphine system examined here,

both by experiment and DFT calculation, the difference in the

D(Rh–Ar^F)_relvalues was much smaller (0.3 kcal mol^-1) than the

corresponding difference in the isonitrile system (3.3 kcal mol^-1).

This result indicates that the total number of ﬂuorines plays a more

signiﬁcant role in the phosphine containing system compared with

the isonitrile system.

A plot of theoretically calculated C–H bond strengths D(Ar^F–

H) vs. experimentally determined Rh–Ar^Fbond strengths D(Rh–

Ar^F) shows an almost linear correlation with a slope of 2.15

(Fig. 7a). In addition, this plot closely matches with the theo-

retically calculated plot (slope = 2.05, Fig. 7b), indicating that

DFT can be used to accurately model these thermodynamics.

The strong similarity between these plots implies that there

is also a strong correlation between D(Rh–Ar^F)^exptand D(Rh–

Ar^F)^calc(see Supporting Information‡). Furthermore, these results

indicate that the effect of ortho-ﬂuorine on the strength of the

Rh–Ar^Fbond is substantial, as concluded in the previously

examined systems Cp*Re(Ar^F)H(CO)₂(slope = 2.25)¹⁹and

Tp¢Rh(Ar^F)H(CNneopentyl) (slope = 2.14).²³

Fig. 7 Plot of relative Rh–Ar^Fbond strength vs. calculated C–H

bond strength (kcal mol^-1); Experimental result (a) and DFT calculated

result (b).

Conclusions

We have succeeded in the synthesis and isolation of the series

of complexes of the type Tp¢Rh(PR₃)(Ar^F)H, where PR₃

structure, the Rh–Ar^Fbond lengths were found to be strongly

affected by the steric repulsion around the rhodium metal center

rather than inductive effect of ﬂuorine substituents. The kinetics

of the reductive eliminations of ﬂuoroarenes from the PMe₃

complexes (3) in benzene-d₆solutions at 140 ^◦C were investigated,

but were unsuccessful because of the formation of Tp¢Rh(PMe₃)₂

(4). Thermal reactions of the PMe₂Ph derivatives (9) in THF-

d₈solution at 120 ^◦C, however, resulted in the intramolecular

C–H bond activation of the phenyl group on the phosphine,

=

PMe₃(3) and PMe₂Ph (9), Ar^F= C₆F₅(a), 2,3,4,5-C₆F₄H (b),

2,3,5,6-C₆F₄H (c), 2,4,6-C₆F₃H₂(d), 2,3-C₆F₂H₃(e), 2,5-C₆F₂H₃

(g), and 2-C₆FH₄(h), as stable crystalline compounds by the

reactions of the [Tp¢Rh(PR₃)] fragment with partially ﬂuorinated

benzene derivatives. The complexes were characterized by NMR

spectroscopy and elemental analysis and the molecular structures

were determined by X-ray crystallographic analysis. In the crystal

10502 | Dalton Trans., 2010, 39, 10495–10509

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2

affording Tp¢Rh(k -C₆H₄-2-PMe₂)H (7). The kinetics of the

Preparation of Tp¢Rh(Ar^F)H(PMe₃) (3) – general procedure

reductive eliminations of ﬂuoroarenes from the complexes (9) were

investigated and these results together with kinetic selectivities

have shown the sensitivity of the Rh–Ar^Fbond energies with ortho-

ﬂuorine substituents. The dependence of the Rh–Ar^Fbond energy

on the number of ortho ﬂuorines is similar to that observed in the

previously reported Tp¢Rh(CNneopentyl)(Ar^F)H system. A plot

of Rh–Ar^Fvs. C–H bond strengths resulted in a line (slope = 2.15)

that closely matches the DFT-calculated value (slope = 2.05), and

is similar to that seen with Tp¢Rh(CNneopentyl)(Ar^F)H system

(slope = 2.14). This study also shows that the replacement of

the isonitrile by a phosphine ligand does not increase the slope

of the correlation. The experimental study gives the same slope

for the phosphine and the isonitrile complexes while the DFT

calculation ﬁnds only a small difference between the slopes. This

difference is probably too small to be detectable in the experimental

studies.

A resealable 5 mm NMR tube containing ~20 mg (0.042 mmol) of

1 was charged with 0.6 mL of Ar^FH in the glove box. The sample

was irradiated, and the reaction was almost complete after 2 h of

1

irradiation as determined by H NMR spectroscopy. Powdered

product was isolated in pure form by ﬂash chromatography

through silica gel in a glass fritted funnel using 5 : 1 hexane–THF

as the eluent, removal of solvent, and then washing with ice-cold

hexane.

For Tp¢Rh(C₆F₅)H(PMe₃) (3a). Yield, 19.5 mg, 71%. Colorless

plate crystals of 3a suitable for X-ray crystallographic analysis

were grown from 1 : 1 hexane : ether solution at room temperature.

1

4

2

¹H NMR (C₆D₆): d -15.75 (dt, J_RhH= J_FH= 19.4 Hz, J_PH

=

2

24.8 Hz, 1H, RhH), 0.99 (d, J_PH= 9.6 Hz, 9H, P(CH₃)₃), 1.52

(s, 3H, pzCH₃), 1.85 (s, 3H, pzCH₃), 2.03 (s, 3H, pzCH₃), 2.17 (s,

3H, pzCH₃), 2.18 (s, 3H, pzCH₃), 2.35 (s, 3H, pzCH₃), 5.38 (s, 1H,

pzH), 5.57 (s, 1H, pzH), 5.82 (s, 1H, pzH). ¹³C{ H} NMR (C₆D₆): d

1

12.77, 12.99, 13.08, 14.53, 16.08, 17.46 (s, pzCH₃), 19.90 (dd, ¹J_PC

=

Experimental

32.6 Hz, ²J_RhC= 1.8 Hz, P(CH₃)₃), 106.03 (d, ⁴J_PC= 2.5 Hz, pzCH),

3

106.63 (s, pzCH), 106.83 (s, pzCH), 143.39 (d, J_PC= 4.1 Hz,

General

pzCq), 143.59 (s, pzCq), 145.50 (s, pzCq), 149.56 (d, ³J_PC= 3.5 Hz,

pzCq), 150.24 (s, pzCq), 150.66 (s, pzCq). Signals assignable to the

six carbons of C₆F₅group were not detected because of multiple

All operations were performed under a nitrogen atmosphere

unless otherwise stated, either on a high-vacuum line using

modiﬁed Schlenk techniques or in a Vacuum Atmospheres

Corp. Dri-Lab. Benzene-d₆, cyclohexane-d₁₂and THF-d₈were

distilled under vacuum from a dark purple solution of ben-

zophenone ketyl and stored in an ampoule with a Teﬂon valve.

Partially ﬂuorinated aromatic compounds were purchased from

Aldrich Chemical Co. and TCI America, dried over magnesium

sulfate, and vacuum-distilled prior to use. Trimethylphosphine

and dimethylphenylphosphine were purchased from Aldrich

Chemical Co., dried over calcium hydride, and vacuum-distilled

prior to use. Potassium tris(3,5-dimethylpyrazolyl)borate (KTp¢)

was purchased from TCI America, and puriﬁed by the previ-

ously reported recrystallization procedure³¹prior to use. The

rhodium precursor fac-RhCl₃(CH₃CN)₃was prepared according

to the previously reported procedure.^32,33The rhodium dihy-

dride complexes Tp¢RhH₂(PMe₃) (1) and Tp¢RhH₂(PPhMe₂)

(5) were prepared according to previously reported procedure,

the latter employing PMe₂Ph in place of PMe₃.²⁵Syntheses of

Tp¢Rh(C₆H₅)H(PMe₃) (2) and Tp¢Rh(C₆D₅)D(PMe₃) (2-d₆) have

coupling with ﬂuorines. ¹⁹F{ H} NMR (C₆D₆): d -41.81 (m, 1

1

Fortho), -55.81 (m, 1 Fortho), -100.52 (m, 1 Fpara), -102.15 (m,

1 Fmeta), -102.76 (m, 1 Fmeta). ³¹P{ H} NMR (C₆D₆): d 0.82

1

(ddd, ¹J_RhP= 129.4 Hz, ⁴J_FP= 21.6, 17.2 Hz, RhP(CH₃)₃). Anal.

Calcd for C₂₄H₃₂BF₅N₆PRh: C, 44.74; H, 5.01. Found: C, 44.70;

H, 4.73.

For Tp¢Rh(2,3,4,5-C₆F₄H)H(PMe₃) (3b). Yield, 22.3 mg, 83%.

Colorless plate crystals of 3b suitable for X-ray crystallographic

◦

1

analysis were grown from hexane at -20 C. H NMR (C₆D₆): d

-16.22 (ddd, ¹J_RhH= 21.6 Hz, ²J_PH= 28.1 Hz, ⁴J_FH= 13.7 Hz, 1H,

RhH), 1.03 (d, ²J_PH= 9.6 Hz, 9H, P(CH₃)₃), 1.53 (s, 3H, pzCH₃),

1.84 (s, 3H, pzCH₃), 2.01 (s, 3H, pzCH₃), 2.14 (s, 3H, pzCH₃), 2.18

(s, 3H, pzCH₃), 2.33 (s, 3H, pzCH₃), 5.37 (s, 1H, pzH), 5.59 (s,

1

1H, pzH), 5.81 (s, 1H, pzH), 6.70 (m, 1H, Rh(o-C₆F₄H)). ¹³C{ H}

NMR (C₆D₆): d 12.69, 12.98, 13.08, 14.58, 16.23, 17.28 (s, pzCH₃),

1

4

20.12 (d, J_PC= 32.6 Hz, P(CH₃)₃), 106.40 (d, J_PC= 3.3 Hz,

pzCH), 106.74 (s, pzCH), 107.44 (s, pzCH), 121.23 (m, CH, o-

C₆F₄H), 143.35 (d, ³J_PC= 2.6 Hz, pzCq), 144.20 (s, pzCq), 145.17

(s, pzCq), 149.77 (s, pzCq), 150.26 (d, ³J_PC= 2.2 Hz, pzCq), 150.51

(s, pzCq). Signals assignable to the carbons of 2,3,5,6-C₆F₄H group

except for the ortho carbon (CH) were not detected because of

1

been reported previously.²⁵All ¹H, ¹³C{ H}, ¹⁹F{ H} and ³¹P{ H}

NMR spectra were recorded on a Bruker Avance 400 MHz

NMR spectrometer. All H chemical shifts are reported in ppm

1

(d) relative to tetramethylsilane and referenced to the chemical

1

multiple coupling with ﬂuorines. ¹⁹F{ H} NMR (C₆D₆): d -47.90

1

shift of residual solvent (benzene, d 7.15). ¹³C{ H} NMR spectra

(m, 1 Fortho), -81.29 (m, 1 Fpara), -97.68 (m, 1 Fmeta), -103.34

1

were referenced to C₆D₆(d 128.0). ¹⁹F{ H} NMR spectra were

1

(m, 1 Fmeta). ³¹P{ H} NMR (C₆D₆): d 1.24 (dm, ¹J_RhP= 131.2 Hz).

1

referenced to external C₆H₅CF₃(d 0). ³¹P{ H} NMR spectra were

Anal. Calcd for C₂₄H₃₃BF₄N₆PRh: C, 46.03; H, 5.31; N, 13.42.

Found: C, 46.30; H, 5.33; N, 13.21.

referenced to external H₃PO₄(d 0). All temperatures for variable-

temperature NMR spectroscopy were calibrated relative to the

chemical shift differences in the NMR spectra of known standards

(25–80 ^◦C, ethylene glycol). All photolysis experiments were

carried out using a water-ﬁltered 200-W Hg–Xe lamp and ﬁltered

using a 270–370 nm band pass ﬁlter. Silica gel was heated overnight

at 200 ^◦C and then stored under nitrogen. A Bruker-AXS SMART

platform diffractometer equipped with an APEX II CCD detector

was used for X-ray crystal structure determination. Elemental

analyses were obtained from Robertson Microlit Laboratories.

For Tp¢Rh(2,3,5,6-C₆F₄H)H(PMe₃) (3c). Yield, 17.4 mg, 65%.

¹H NMR (C₆D₆): d -15.66 (ddd, ¹J_RhH= 18.4 Hz, ²J_PH= 24.8 Hz,

⁴J_FH= 16.0 Hz, 1H, RhH), 1.04 (d, ²J_PH= 9.6 Hz, 9H, P(CH₃)₃),

1.60 (s, 3H, pzCH₃), 1.92 (s, 3H, pzCH₃), 2.04 (s, 3H, pzCH₃), 2.20

(s¥2, 3H¥2, pzCH₃), 2.36 (s, 3H, pzCH₃), 5.39 (s, 1H, pzH), 5.58

1

(s, 1H, pzH), 5.83 (s, 1H, pzH), 6.52 (m, 1H, p-C₆F₄H). ¹³C{ H}

NMR (C₆D₆): d 12.78, 13.00, 13.07, 14.56, 16.11, 17.46 (s, pzCH₃),

20.00 (d, ¹J_PC= 32 Hz, P(CH₃)₃), 100.36 (t, ²J_FC= 23.5 Hz, CH,

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©

4

p-C₆F₄H), 106.01 (d, J_PC= 3.6 Hz, pzCH), 106.60 (s, pzCH),

at 120 ^◦C for 1 month or more of 1,3-C₆F₂H₄solution of the crude

106.81 (s, pzCH), 143.28 (d, ³J_PC= 2.5 Hz, pzCq), 143.50 (s, pzCq),

145.39 (s, pzCq), 149.62 (d, ³J_PC= 2.5 Hz, pzCq), 150.26 (s, pzCq),

150.63 (s, pzCq). Signals assignable to the carbons of 2,3,5,6-

C₆F₄H group except for the para carbon (CH) were not detected

mixture did not result in the quantitative formation of 3f and 3f

1

could not be isolated as pure form. For 3f (major product): H

1

2

NMR (C₆D₆): d -16.24 (ddd, J_RhH= 22.2 Hz, J_PH= 28.9 Hz,

⁴J_FH= 12.0 Hz, 1H, RhH), 1.12 (d, ²J_PH= 9.6 Hz, 9H, P(CH₃)₃),

1.61 (s, 3H, pzCH₃), 1.93 (s, 3H, pzCH₃), 2.09 (s, 3H, pzCH₃),

2.21 (s, 3H, pzCH₃), 2.22 (s, 3H, pzCH₃), 2.36 (s, 3H, pzCH₃), 5.43

(s, 1H, pzH), 5.63 (s, 1H, pzH), 5.86 (s, 1H, pzH), 6.39 (m, 1H,

because of multiplecouplingwithﬂuorines. ¹⁹F{ H} NMR (C₆D₆):

1

d -57.21 (m, 1 Fortho), -59.83 (m, 1 Fortho), -79.00 (m, 1 Fmeta),

-79.61 (m, 1 Fmeta). ³¹P{ H} NMR (C₆D₆): d 0.96 (ddd, ¹J_RhP

=

1

130.4 Hz, ⁴J_FP= 22.5, 16.1 Hz). Anal. Calcd for C₂₄H₃₃BF₄N₆PRh:

C₆F₂H₃), 6.73 (m, 1H, C₆F₂H₃), 6.96 (m, 1H, C₆F₂H₃). ¹⁹F{ H}

C, 46.03; H, 5.31; N, 13.42. Found: C, 46.04; H, 5.35; N, 13.17.

NMR (C₆D₆): d -18.67 (m, 1 Fortho), -25.49 (m, 1 Fortho).

1

³¹P{ H} NMR (C₆D₆): d 1.94 (dm, ¹J_RhP= 130.7 Hz, RhP(CH₃)₃).

Tp¢Rh(2,4,6-C₆F₃H₂)H(PMe₃) (3d). Yield, 23.7 mg, 91%. Col-

orless plate crystals of 3d suitable for X-ray crystallographic

analysis were grown from 1 : 1 hexane : ether solution at room

For Tp¢Rh(2,5-C₆F₂H₃)H(PMe₃) (3g). Yield, 22.5 mg, 89%.

Colorless plate crystals of 3g suitable for X-ray crystallographic

analysis were grown from 1 : 1 hexane : ether solution at room

1

temperature. H NMR (C₆D₆): d -15.88 (ddd, J_RhH= 19.6 Hz,

²J_PH= 25.8 Hz, ⁴J_FH= 14.1 Hz, 1H, RhH), 1.10 (d, ²J_PH= 9.6 Hz,

9H, P(CH₃)₃), 1.67 (s, 3H, pzCH₃), 2.00 (s, 3H, pzCH₃), 2.08 (s,

3H, pzCH₃), 2.21 (s, 3H, pzCH₃), 2.23 (s, 3H, pzCH₃), 2.37 (s, 3H,

pzCH₃), 5.44 (s, 1H, pzH), 5.60 (s, 1H, pzH), 5.86 (s, 1H, pzH), 6.27

1

temperature. H NMR (C₆D₆): d -16.23 (ddd, J_RhH= 22.2 Hz,

²J_PH= 28.3 Hz, ⁴J_FH= 11.9 Hz, 1H, RhH), 1.16 (d, ²J_PH= 9.6 Hz,

9H, P(CH₃)₃), 1.67 (s, 3H, pzCH₃), 1.98 (s, 3H, pzCH₃), 2.04 (s, 3H,

pzCH₃), 2.21 (s¥2, 3H¥2, pzCH₃), 2.36 (s, 3H, pzCH₃), 5.40 (s, 1H,

pzH), 5.62 (s, 1H, pzH), 5.82 (s, 1H, pzH), 6.56 (m, 1H, C₆F₂H₃),

(m, 1H, C₆F₃H₂), 6.59 (m, 1H, C₆F₃H₂). ¹³C{ H} NMR (C₆D₆):

1

6.71 (m, 1H, C₆F₂H₃), 6.97 (m, 1H, C₆F₂H₃). ¹³C{ H} NMR

d 12.85, 13.05, 13.09, 14.63, 16.22, 17.46 (s, pzCH₃), 20.15 (d,

¹J_PC= 32.2 Hz, P(CH₃)₃), 97.48 (dd, ²J_FC= 35.2, 23.8 Hz, CH, m-

C₆F₃H₂), 98.71 (dd, ²J_FC= 36.0, 22.7 Hz, CH, m-C₆F₃H₂), 105.90

(C₆D₆): d 12.74, 13.04, 13.10, 14.70, 16.32, 17.29 (s, pzCH₃), 20.29

1

4

(d, J_PC= 32.3 Hz, P(CH₃)₃), 106.34 (d, J_PC= 3.4 Hz, pzCH),

2

4

106.59 (s, pzCH), 107.33 (s, pzCH), 109.59 (dd, J_FC= 24.6 Hz,

(d, J_PC= 3.3 Hz, pzCH), 106.44 (s, pzCH), 106.68 (s, pzCH),

³J_FC= 9.3 Hz, CH, m-C₆F₂H₃), 112.47 (dd, ²J_FC= 35.8 Hz, ³J_FC

=

143.05 (s, pzCq), 143.34 (s, pzCq), 145.11 (s, pzCq), 149.72 (s,

pzCq), 150.18 (s, pzCq), 150.41 (s, pzCq). Signals for the carbons

of 2,4,6-C₆F₃H₂group except for the meta carbons (CH) could not

8.5 Hz, CH, p-C₆F₂H₃), 142.24 (m, br, C, ipso-C₆F₂H₃), 143.10 (d,

³J_PC= 2.4 Hz, pzCq), 143.98 (s, pzCq), 144.85 (s, pzCq), 149.77 (s,

pzCq), 150.27 (s, pzCq), 150.43 (d, ³J_PC= 2.4 Hz, pzCq), 157.89

(d, ¹J_FC= 241.5 Hz, CF, m-C₆F₂H₃), 165.34 (d, ¹J_FC= 223.7 Hz,

CF, o-C₆F₂H₃). The signal assignable to the ortho CH of 2,5-

C₆F₂H₃group was not detected because of overlap with solvent

be assigned because of multiple coupling with ﬂuorines. ¹⁹F{ H}

1

NMR (C₆D₆): d -10.31 (m, 1 Fortho), -22.27 (m, 1 Fortho), -57.46

(m, 1 Fmeta). ³¹P{ H} NMR (C₆D₆): d 1.36 (ddd, ¹J_RhP= 131.0 Hz,

1

⁴J_FP= 20.1, 17.8 Hz). Anal. Calcd for C₂₄H₃₄BF₃N₆PRh: C, 47.39;

peaks. ¹⁹F{ H} NMR (C₆D₆): d -28.35 (m, 1 Fortho), -60.54 (m,

1

H, 5.63; N, 13.82. Found: C, 47.28; H, 5.38; N, 13.64.

1 Fmeta). ³¹P{ H} NMR (C₆D₆): d 1.69 (dm, J_RhP= 132.7 Hz).

Anal. Calcd for C₂₄H₃₅BF₂N₆PRh: C, 48.84; H, 5.98; N, 14.24.

Found: C, 48.61; H, 5.81; N, 14.07.

1

For Tp¢Rh(2,3-C₆F₂H₃)H(PMe₃) (3e). 3e forms along with

1

its isomer, Tp¢Rh(3,4-C₆F₂H₃)H(PMe₃), as judged by H NMR

spectroscopy. Heating at 120 ^◦C for 2 weeks in 1,2-C₆F₂H₄solution

of the crude mixture resulted in the almost quantitative formation

1

For Tp¢Rh(2-C₆FH₄)H(PMe₃) (3h). Yield, 17.2 mg, 70%. H

1

2

of 3e. Yield, 21.3 mg, 84%. ¹H NMR (C₆D₆): d -16.24 (ddd, ¹J_RhH

22.2 Hz, ²J_PH= 28.4 Hz, ⁴J_FH= 13.2 Hz, 1H, RhH), 1.14 (d, ²J_PH

=

NMR (C₆D₆): d -16.32 (ddd, J_RhH= 22.8 Hz, J_PH= 28.4 Hz,

⁴J_FH= 12.0 Hz, 1H, RhH), 1.24 (d, ²J_PH= 9.6 Hz, 9H, P(CH₃)₃),

1.73 (s, 3H, pzCH₃), 2.00 (s, 3H, pzCH₃), 2.10 (s, 3H, pzCH₃),

2.25 (s, 3H, pzCH₃), 2.27 (s, 3H, pzCH₃), 2.45 (s, 3H, pzCH₃), 5.43

(s, 1H, pzH), 5.64 (s, 1H, pzH), 5.87 (s, 1H, pzH), 6.59 (m, 1H,

C₆FH₄), 6.61 (m, 1H, C₆FH₄), 6.86 (m, 1H, C₆FH₄), 6.92 (m, 1H,

=

9.6 Hz, 9H, P(CH₃)₃), 1.60 (s, 3H, pzCH₃), 1.95 (s, 3H, pzCH₃),

2.08 (s, 3H, pzCH₃), 2.21 (s, 3H, pzCH₃), 2.22 (s, 3H, pzCH₃),

2.36 (s, 3H, pzCH₃), 5.40 (s, 1H, pzH), 5.63 (s, 1H, pzH), 5.86

(s, 1H, pzH), 6.38 (m, 1H, C₆F₂H₃), 6.70 (m, 1H, C₆F₂H₃), 6.86

1

C₆FH₄). ¹³C{ H} NMR (C₆D₆): d 12.76, 13.05, 13.14, 14.70, 16.50,

(m, 1H, C₆F₂H₃). ¹³C{ H} NMR (C₆D₆): d 12.72, 13.01, 13.12,

1

14.66, 16.48, 17.30 (s, pzCH₃), 20.37 (d, ¹J_PC= 32.4 Hz, P(CH₃)₃),

17.30 (s, pzCH₃), 20.48 (d, J_PC= 32.2 Hz, P(CH₃)₃), 106.21 (d,

⁴J_PC= 3.4 Hz, pzCH), 106.52 (s, pzCH), 107.15 (s, pzCH), 125.59

4

106.24 (d, J_PC= 3.4 Hz, pzCH), 106.62 (s, pzCH), 107.19 (s,

2

(d, J_FC= 31.6 Hz, CH, m-C₆FH₄), 122.23 (s, CH, m-C₆FH₄),

pzCH), 110.48 (d, J_FC= 17.2 Hz, CH, p-C₆F₂H₃), 121.62 (d,

3

1

³J_FC= 7.2 Hz, CH, m-C₆F₂H₃), 137.64 (d, ³J_FC= 14.3 Hz, CH, o-

C₆F₂H₃), 142.32 (m, br, C, ipso-C₆F₂H₃), 142.98 (d, ³J_PC= 2.2 Hz,

pzCq), 143.82 (s, pzCq) 144.87 (s, pzCq), 149.87 (s, pzCq), 150.02

123.62 (d, J_FC= 8.0 Hz, CH, p-C₆FH₄), 138.15 (ddd, J_RhC

=

40.4 Hz, ²J_PC= 15.9 Hz, ²J_FC= 32.5 Hz, C, ipso-C₆FH₄), 124.83

3

(s, pzCq), 143.40 (d, J_FC= 15.5 Hz, CH, o-C₆FH₄), 143.73 (s,

1

2

pzCq), 144.67 (s, pzCq), 149.86 (s, pzCq), 150.20 (s, pzCq) 150.65

(dd, J_FC= 246.7 Hz, J_FC= 32.2 Hz, CF, m-C₆F₂H₃), 150.39

(s, pzCq), 169.33 (d, J_FC= 231.5 Hz, CF, o-C₆FH₄). ¹⁹F{ H}

1

3

1

(s, pzCq), 150.54 (d, J_PC= 2.3 Hz, pzCq), 156.15 (dm, J_FC

=

NMR (C₆D₆): d -20.41 (m, 1 Fortho). ³¹P{ H} NMR (C₆D₆): d

1

226.6 Hz, CF, o-C₆F₂H₃). ¹⁹F{ H} NMR (C₆D₆): d -47.15 (m, 1

1

2.03 (dm, ¹J_RhP= 131.4 Hz). Anal. Calcd for C₂₄H₃₆BFN₆PRh: C,

Fortho), -78.43 (m, 1 Fmeta). ³¹P{ H} NMR (C₆D₆): d 1.69 (dm,

1

¹J_RhP= 131.3 Hz). Anal. Calcd for C₂₄H₃₅BF₂N₆PRh: C, 48.84; H,

50.37; H, 6.34; N, 14.69. Found: C, 50.20; H, 6.10; N, 14.48.

5.98; N, 14.24. Found: C, 49.11; H, 6.03; N, 14.37.

Preparation of Tp¢Rh(C₆H₅)H(PPhMe₂) (6)

For Tp¢Rh(2,6-C₆F₂H₃)H(PMe₃) (3f). 3f forms along with

the isomers, Tp¢Rh(2,4-C₆F₂H₃)H(PMe₃) and Tp¢Rh(3,5-

C₆F₂H₃)H(PMe₃), as judged by H NMR spectroscopy. Heating

A resealable 5 mm NMR tube containing 20.5 mg (0.0380 mmol)

of 5 was charged with 0.7 mL of C₆H₆in the glove box. The

1

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The Royal Society of Chemistry 2010

©

2

1

ipso-h -C₆H₄-PMe₂). ³¹P{ H} NMR (C₆D₆): d -65.12 (d, ¹J_RhP

=

sample was irradiated, and after 5 h the starting material 5 had

disappeared completely as judged by the ¹H NMR spectroscopy.

6 and 7 were seen in a ratio of 6.8 : 1. Heating at 120 ^◦C for 1 h in

C₆H₆solution resulted in the almost quantitative formation of 6. 6

was isolated as a colorless powder (16.4 mg, 0.0266 mmol, 70%) in

pure form by ﬂash chromatography through silica gel in a glass frit

funnel using 5 : 1 hexane–THF as the eluent, removal of solvent,

and then washing with a minimum amount of ice-cold hexane

114.2 Hz). Anal. Calcd for C₂₃H₃₃BN₆PRh: C, 51.32; H, 6.18; N,

15.61. Found: C, 51.51; H, 5.97; N, 15.38.

Preparation of Tp¢Rh(Ar^F)H(PPhMe₂) (9) – general procedure

A resealable 5 mm NMR tube containing ~20 mg (0.038 mmol) of

5 was charged with 0.7 mL of Ar^FH in the glove box. The sample

was irradiated for 5 h, at which point the starting material 5 had

1

three times. H NMR (C₆D₆): d -16.29 (dd, J_RhH= 23.3 Hz,

1

²J_PH= 27.6 Hz, 1H, RhH), 1.29 (d, ²J_PH= 8.8 Hz, 3H, PPhMe₂),

disappeared completely as judged by the H NMR spectroscopy

2

to form 9 and _◦7 (ratio given in Schemes 6 and 7). Heating the

mixture at 120 C for 1 h in Ar^FH solution resulted in the almost

quantitative formation of 9. The product was obtained as a powder

by ﬂash chromatography through silica gel in a glass fritted funnel

using 5 : 1 hexane–THF as the eluent, removal of solvent, and then

washing with a minimum amount of ice-cold hexane.

1.63 (s, 3H, pzCH₃), 1.72 (d, J_PH= 8.4 Hz, 3H, PPhMe₂), 1.85

(s, 3H, pzCH₃), 2.02 (s, 3H, pzCH₃), 2.15 (s, 3H, pzCH₃), 2.25 (s,

3H, pzCH₃), 2.42 (s, 3H, pzCH₃), 5.45 (s, 1H, pzH), 5.52 (s, 1H,

pzH), 5.89 (s, 1H, pzH), 6.84 (t, J = 7.4 Hz, 1H, RhPh), 6.93

(m, 3H, PPhMe₂), 7.00 (t, J = 7.0 Hz, 1H, RhPh), 7.13 (t, J =

7.0 Hz, 1H, RhPh), 7.26 (d, J = 7.6 Hz, 1H, RhPh), 7.66 (m, 2H,

1

PPhMe₂), 7.91 (d, J = 6.8 Hz, 1H, RhPh). ¹³C{ H} NMR(C₆D₆): d

For Tp¢Rh(C₆F₅)H(PPhMe₂) (9a). Yield, 22.1 mg,

0.0312 mmol, 82%. Colorless single crystals of 9a suitable

for X-ray crystallographic analysis were grown from hexane at

12.86, 13.12, 13.20, 15.50, 16.02, 16.78 (s, pzCH₃), 18.36 (d, ¹J_PC

=

1

2

29.8 Hz, PPhMe₂), 21.94 (dd, J_PC= 35.0 Hz, J_RhC= 2.4 Hz,

4

PPhMe₂), 106.29 (s, pzCH), 106.40 (d, J_PC= 4.0 Hz, pzCH),

◦

-20 C. 9a: ¹H NMR (C₆D₆): d –15.18 (dt, ¹J_RhH= J_FH= 16.0 Hz,

4

107.23 (s, pzCH), 121.70 (s, RhPh), 125.91 (s, RhPh), 126.26 (s,

RhPh), 129.70 (s, PPhMe₂), 131.36 (d, ¹J_PC= 10.7 Hz, PPhMe₂),

138.38 (s, PPhMe₂), 138.80 (s, PPhMe₂), 141.08 (s, RhPh), 142.80

(d, ³J_PC= 2.0 Hz, pzCq), 143.86 (s, pzCq), 145.01 (s, RhPh), 144.98

(d, ³J_PC= 6.1 Hz, pzCq), 150.23 (s, pzCq), 150.40 (s, pzCq), 151.17

(s, pzCq), 154.22 (dd, ¹J_RhC= 35.2 Hz, ²J_PC= 13.1 Hz, ipso- RhPh).

²J_PH= 23.6 Hz, 1H, RhH), 1.17 (d, ²J_PH= 6.0 Hz, 3H, PPhMe₂),

2

1.53 (d, J_PH= 9.2 Hz, 3H, PPhMe₂), 1.56 (s, 3H, pzCH₃), 1.61

(s, 3H, pzCH₃), 1.79 (s, 3H, pzCH₃), 2.06 (s, 3H, pzCH₃), 2.18

(s, 3H, pzCH₃), 2.38 (s, 3H, pzCH₃), 5.33 (s, 1H, pzH), 5.41 (s,

1H, pzH), 5.82 (s, 1H, pzH), 6.95 (m, 3H, PPhMe₂), 7.61 (m, 2H,

PPhMe₂). ¹³C{ H} NMR (C₆D₆): d 12.77, 12.97, 13.14, 14.70,

1

³¹P{ H} NMR (C₆D₆): d 15.35 (d, ¹J_RhP= 149.5 Hz). Anal. Calcd

15.94, 16.21 (s, pzCH₃), 17.24 (d, ¹J_PC= 30.4 Hz, PPhMe₂), 22.20

for C₂₉H₃₉BN₆PRh: C, 56.51; H, 6.38; N, 13.64. Found: C, 56.28;

H, 6.25; N, 13.40.

(dd, ¹J_PC= 33.4 Hz, ²J_RhC= 3.4 Hz, PPhMe₂), 106.19 (d, ⁴J_PC

=

3.1 Hz, pzCH), 106.74 (s, pzCH), 107.00 (s, pzCH), 129.90 (s,

1

2

PPhMe₂), 131.61 (dd, J_PC= 9.8 Hz, J_RhC= 4.0 Hz, PPhMe₂),

138.05 (s, PPhMe₂), 138.50 (s, PPhMe₂), 143.45 (d, ³J_PC= 2.2 Hz,

pzCq), 143.57 (s, pzCq), 145.24 (s, pzCq), 149.75 (s, pzCq),

150.42 (s, pzCq), 151.68 (s, pzCq). Signals assignable to the six

carbons of C₆F₅group were not detected because of multiple

Preparation of Tp¢Rh(C₆D₅)D(PPhMe₂) (6-d₆)

Prepared as for 6 but with C₆D₆solvent. Anal. Calcd for

C₂₉H₃₃D₆BN₆PRh: C, 55.96; H, 6.23; N, 13.50. Found: C, 55.68;

H, 6.33; N, 13.30.

1

coupling with ﬂuorines. ¹⁹F{ H} NMR (C₆D₆): d -40.56 (m, 1

Preparation of Tp¢Rh(j²-C₆H₄-2-PMe₂)H (7)

Fortho), -55.38 (m, 1 Fortho), -100.14 (m, 1 Fpara), -101.98 (m,

1

1 Fmeta), -102.62 (m, 1 Fmeta). ³¹P{ H} NMR (C₆D₆): d 10.23

A resealable 5 mm NMR tube containing 16.4 mg (0.0266 mmol)

of 6 was charged with 0.7 mL of THF in the glove box. Heating

of the sample at 120 ^◦C for 1 h resulted in the almost quantitative

formation of 7. 7 was obtained as a colorless powder (12.0 mg,

0.0223 mmol, 84%) in pure form by washing with ice-cold hexane.

Colorless single crystals of 7 suitable for X-ray crystallographic

analysis were grown from hexane at -20 ^◦C. 7: ¹H NMR (C₆D₆):

1

4

(ddd, J_RhP= 132.4 Hz, J_FP= 13.4, 8.2 Hz). Anal. Calcd for

C₂₉H₃₄BF₅N₆PRh: C, 49.31; H, 4.85; N, 11.90. Found: C, 49.57;

H, 4.77; N, 11.67.

For Tp¢Rh(2,3,4,5-C₆F₄H)H(PPhMe₂) (9b). Yield, 20.5 mg,

79%. Colorless single crystals of 9b suitable for X-ray crystal-

◦

1

lographic analysis were grown from hexane at -20 C. H NMR

1

2

1

2

4

d -14.93 (dd, J_RhH= 22.0 Hz, J_PH= 35.2 Hz, 1H, RhH), 1.12

(C₆D₆): d –15.59 (ddd, J_RhH= 19.6 Hz, J_PH= 26.6 Hz, J_FH

=

2

(d, ²J_PH= 10.8 Hz, 3H, h -C₆H₄–PMe₂), 1.50 (s, 3H, pzCH₃), 1.58

12.8 Hz, 1H, RhH), 1.25 (d, J_PH= 9.2 Hz, 3H, PPhMe₂), 1.67

2

(d, ²J_PH= 10.4 Hz, 3H, h -C₆H₄–PMe₂), 2.16 (s, 3H, pzCH₃), 2.25

(s, 3H, pzCH₃), 1.74 (d, J_PH= 4.2 Hz, 3H, PPhMe₂), 1.75 (s,

(s¥2, 3H¥2, pzCH₃), 2.26 (s, 3H, pzCH₃), 2.52 (s, 3H, pzCH₃), 5.63

3H, pzCH₃), 1.86 (s, 3H, pzCH₃), 2.12 (s, 3H, pzCH₃), 2.26 (s,

3H, pzCH₃), 2.41 (s, 3H, pzCH₃), 5.47 (s, 1H, pzH), 5.49 (s, 1H,

pzH), 5.90 (s, 1H, pzH), 6.80 (m, 1H, Rh(o-C₆F₄H)), 7.01 (m,

2

(s, 1H, pzH), 5.71 (s¥2, 1H¥2, pzH), 6.69 (m, 1H, h -C₆H₄-PMe₂),

2

6.95 (m, 1H, h -C₆H₄-PMe₂), 7.02 (t, J = 7.4 Hz, 1H, h -C₆H₄-

PMe₂), 7.34 (t, J = 5.6 Hz, 1H, h -C₆H₄-PMe₂). ¹³C{ H} NMR

3H, PPhMe₂), 7.65 (m, 2H, PPhMe₂). ¹³C{ H} NMR (C₆D₆):

2

1

2

(C₆D₆): d 12.32 (d, ¹J_PC= 13.4 Hz, h -C₆H₄–PMe₂), 12.71, 12.83,

d 12.71, 13.00, 13.16, 14.79, 16.14, 16.21 (s, pzCH₃), 17.97 (d,

12.93 (s¥2), 16.01, 16.18 (s, pzCH₃), 20.53 (d, ¹J_PC= 33.1 Hz, h -

¹J_PC= 30.6 Hz, PPhMe₂), 22.82 (dm, J_PC= 39.3 Hz, PPhMe₂),

2

1

4

C₆H₄–PMe₂), 105.48 (s, pzCH), 106.01 (d, ⁴J_PC= 4.9 Hz, pzCH),

106.54 (d, J_PC= 4.1 Hz, pzCH), 106.81 (s, pzCH), 107.61 (s,

2

107.23 (s, pzCH), 122.39 (d, J = 9.8 Hz, h -C₆H₄-PMe₂), 123.32 (s,

pzCH), 121.32 (m, CH, o-C₆F₄H), 129.92 (s, PPhMe₂), 131.55

(dd, ¹J_PC= 10.7 Hz, ²J_RhC= 3.0 Hz, PPhMe₂), 137.72 (s, PPhMe₂),

138.16 (s, PPhMe₂), 143.46 (s, pzCq), 144.28 (s, pzCq), 144.82 (s,

pzCq), 150.09 (s, pzCq), 150.53 (s, pzCq), 151.40 (s, pzCq). Signals

assignable to the six carbons of 2,3,4,5-C₆F₄H group except for the

2

h -C₆H₄-PMe₂), 129.75 (s, h -C₆H₄-PMe₂), 135.57 (d, J = 10.3 Hz,

2

h -C₆H₄-PMe₂), 143.24 (s, pzCq), 143.38 (s, pzCq), 143.45 (d,

³J_PC= 2.2 Hz, pzCq), 148.86 (s, pzCq), 150.30 (s, pzCq), 150.76

(s, pzCq), 151.75 (s, h -C₆H₄-PMe₂), 151.95 (d, ¹J_RhC= 31.7 Hz,

2

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The Royal Society of Chemistry 2010

Dalton Trans., 2010, 39, 10495–10509 | 10505

©

ortho carbon (CH) were not detected because of multiple coupling

and 7, as judged by ¹H NMR spectroscopy. Heating at 120 ^◦C for

1 h in 1,2-C₆F₂H₄solution resulted in the quantitative formation

of 9e. Yield, 21.9 mg, 89%. Colorless single crystals of 9e suitable

1

with ﬂuorines. ¹⁹F{ H} NMR (C₆D₆): d -47.05 (m, 1 Fortho),

-81.12 (m, 1 Fpara), -97.47 (m, 1 Fmeta), -102.91 (m, 1 Fmeta).

1

³¹P{ H} NMR (C₆D₆): d 11.12 (dm, J_RhP= 136.8 Hz). Anal.

Calcd for C₂₉H₃₅BF₄N₆PRh: C, 50.60; H, 5.13; N, 12.21. Found:

C, 50.34; H, 4.89; N, 11.97.

for X-ray crystallographic analysis were grown from hexane at

◦

1

-20 C. 9e: H NMR (C₆D₆): d –15.70 (ddd, J_RhH= 20.2 Hz,

²J_PH= 27.0 Hz, ⁴J_FH= 12.0 Hz, 1H, RhH), 1.28 (d, ²J_PH= 9.2 Hz,

3H, PPhMe₂), 1.65 (s, 3H, pzCH₃), 1.72 (s, 3H, pzCH₃), 1.80

For Tp¢Rh(2,3,5,6-C₆F₄H)H(PPhMe₂) (9c). Yield, 19.9 mg,

76%. Colorless single crystals of 9c suitable for_◦X-ray crystallo-

graphic analysis were grown from hexane at -20 C. 9c: ¹H NMR

2

(d, J_PH= 9.2 Hz, 3H, PPhMe₂), 1.87 (s, 3H, pzCH₃), 2.11 (s,

3H, pzCH₃), 2.22 (s, 3H, pzCH₃), 2.39 (s, 3H, pzCH₃), 5.43 (s,

1H, pzH), 5.44 (s, 1H, pzH), 5.84 (s, 1H, pzH), 6.37 (m, 1H,

C₆F₂H₃), 6.71 (m, 1H, C₆F₂H₃), 6.88 (m, 1H, C₆F₂H₃), 6.92 (m,

4

(C₆D₆): d –15.09 (dt, ¹J_RhH= J_FH= 15.2 Hz, ²J_PH= 23.6 Hz, 1H,

RhH), 1.21 (d, ²J_PH= 9.2 Hz, 3H, PPhMe₂), 1.59 (s, 3H, pzCH₃),

3H, PPhMe₂), 7.63 (m, 2H, PPhMe₂). ¹³C{ H} NMR (C₆D₆): d

1

2

1.60 (d, J_PH= 8.0 Hz, 3H, PPhMe₂), 1.68 (s, 3H, pzCH₃), 1.85

12.74, 13.04, 13.22, 14.88, 16.28, 16.36 (s, pzCH₃), 18.33 (d, ¹J_PC

=

(s, 3H, pzCH₃), 2.07 (s, 3H, pzCH₃), 2.19 (s, 3H, pzCH₃), 2.39

(s, 3H, pzCH₃), 5.39 (s, 1H, pzH), 5.42 (s, 1H, pzH), 5.82 (s,

1H, pzH), 6.53 (m, 1H, Rh(p-C₆F₄H)), 6.95 (m, 3H, PPhMe₂),

1

2

30.5 Hz, PPhMe₂), 23.26 (dd, J_PC= 35.3 Hz, J_RhC= 2.9 Hz,

4

PPhMe₂), 106.37 (d, J_PC= 3.3 Hz, pzCH), 106.63 (s, pzCH),

2

107.36 (s, pzCH), 110.68 (d, J_FC= 17.1 Hz, CH, p-C₆F₂H₃),

1

7.66 (m, 2H, PPhMe₂). ¹³C{ H} NMR (C₆D₆): d 12.78, 12.99,

3

121.61 (d, J_FC= 4.4 Hz, CH, m-C₆F₂H₃), 129.75 (s, PPhMe₂),

1

13.13, 14.74, 19.92, 16.24 (s, pzCH₃), 17.41 (d, J_PC= 30.3 Hz,

1

2

131.74 (dd, J_PC= 10.2 Hz, J_RhC= 2.2 Hz, PPhMe₂), 137.65

1

2

PPhMe₂), 22.37 (d, J_PC= 29.6 Hz, PPhMe₂), 100.59 (t, J_FC

=

3

(d, J_FC= 14.1 Hz, CH, o-C₆F₂H₃), 138.13 (s, PPhMe₂), 138.56

23.3 Hz, CH, p-C₆F₄H), 106.18 (d, ⁴J_PC= 3.4 Hz, pzCH), 106.71 (s,

(s, PPhMe₂), 141.62 (dddd, br, ¹J_RhC= 41.2 Hz, C, ipso-C₆F₂H₃),

143.04 (d, ³J_PC= 2.5 Hz, pzCq), 143.87 (s, pzCq), 144.51 (s, pzCq),

pzCH), 106.94 (s, pzCH), 129.80 (s, PPhMe₂), 131.70 (dd, ¹J_PC

=

2

9.8 Hz, J_RhC= 4.4 Hz, PPhMe₂), 138.24 (s, PPhMe₂), 138.69 (s,

PPhMe₂), 143.41 (d, ³J_PC= 2.2 Hz, pzCq), 143.48 (s, pzCq), 145.13

(s, pzCq), 149.81 (s, pzCq), 150.45 (s, pzCq), 151.64 (s, pzCq).

Signals assignable to the carbons of 2,3,5,6-C₆F₄H group except

for the para carbon (CH) were not detected because of multiple

1

2

150.10 (dd, J_FC= 245.2 Hz, J_FC= 22.6 Hz, CF, m-C₆F₂H₃).

150.20 (s, pzCq), 150.82 (s, pzCq), 151.46 (s, pzCq), 156.48 (dm,

¹J_FC= 225.0 Hz, CF, o-C₆F₂H₃). ¹⁹F{ H} NMR (C₆D₆): d -46.30

1

(m, 1 Fortho), -78.25 (m, 1 Fmeta). ³¹P{ H} NMR (C₆D₆): d

1

11.60 (ddd, ¹J_RhP= 140.1 Hz, ⁴J_FP= 16.7, 6.5 Hz). Anal. Calcd for

C₂₉H₃₇BF₂N₆PRh: C, 53.39; H, 5.72; N, 12.88. Found: C, 53.21;

H, 5.51; N, 12.85.

coupling with ﬂuorines. ¹⁹F{ H} NMR (C₆D₆): d -41.67 (m, 1

1

Fortho), -57.03 (m, 1 Fortho), -79.16 (m, 1 Fmeta), -80.01 (m, 1

Fmeta). ³¹P{ H} NMR (C₆D₆): d 10.40 (dm, J_RhP= 133.0 Hz).

Anal. Calcd for C₂₉H₃₅BF₄N₆PRh: C, 50.60; H, 5.13; N, 12.21.

Found: C, 50.82; H, 4.88; N, 11.95.

1

For Tp¢Rh(2,6-C₆F₂H₃)H(PPhMe₂) (9f). Photolysis resulted

in the formation of 9f with the isomers Tp¢Rh(2,4-

C₆F₂H₃)H(PPhMe₂) and Tp¢Rh(3,5-C₆F₂H₃)H(PPhMe₂), and 7,

as judged by ¹H NMR spectroscopy. Heating at 120 ^◦C for more

than 1 month in 1,3-C₆F₂H₄solution the crude mixture did not

afford the pure 9f and it could not be isolated as pure form. For 9f:

¹H NMR (C₆D₆): d –15.83 (ddd, ¹J_RhH= 20.2 Hz, ²J_PH= 27.6 Hz,

⁴J_FH= 11.2 Hz, 1H, RhH), 1.24 (d, ²J_PH= 8.9 Hz, 3H, PPhMe₂),

1.72 (s, 3H, pzCH₃), 1.81 (s, 3H, pzCH₃), 1.88 (d, ²J_PH= 8.9 Hz,

3H, PPhMe₂), 1.91 (s, 3H, pzCH₃), 2.09 (s, 3H, pzCH₃), 2.18 (s,

3H, pzCH₃), 2.40 (s, 3H, pzCH₃), 5.44 (s, 1H, pzH), 5.47 (s, 1H,

pzH), 5.86 (s, 1H, pzH), 6.37 (m, 1H, Rh(m-C₆F₂H₃)), 6.77 (m,

1H, Rh(m-C₆F₂H₃)), 6.95 (m, 3H, PPhMe₂), 6.99 (m, 1H, Rh(p-

For Tp¢Rh(2,4,6-C₆F₃H₂)H(PPhMe₂) (9d). Yield, 21.6 mg,

85%. Colorless crystals of 9d suitable for X-ray crystallographic

◦

1

analysis were grown from hexane at -20 C. H NMR (C₆D₆): d

–15.33 (ddd, ¹J_RhH= 17.6 Hz, ²J_PH= 24.0 Hz, ⁴J_FH= 14.0 Hz, 1H,

RhH), 1.28 (d, ²J_PH= 8.8 Hz, 3H, PPhMe₂), 1.63 (s, 3H, pzCH₃),

2

1.67 (d, J_PH= 8.8 Hz, 3H, PPhMe₂), 1.75 (s, 3H, pzCH₃), 1.92

(s, 3H, pzCH₃), 2.11 (s, 3H, pzCH₃), 2.21 (s, 3H, pzCH₃), 2.41

(s, 3H, pzCH₃), 5.42 (s, 1H, pzH), 5.48 (s, 1H, pzH), 5.86 (s, 1H,

pzH), 6.26 (m, 1H, Rh(m-C₆F₄H)), 6.61 (m, 1H, Rh(m-C₆F₄H)),

1

6.97 (m, 3H, PPhMe₂), 7.71 (m, 2H, PPhMe₂). ¹³C{ H} NMR

1

C₆F₂H₃)), 7.66 (m, 2H, PPhMe₂). ¹⁹F{ H} NMR (C₆D₆): d -17.56

(C₆D₆): d 12.85, 13.05, 13.17, 14.82, 16.08, 16.34 (s, pzCH₃), 17.68

(d, ¹J_PC= 30.0 Hz, PPhMe₂), 22.63 (d, ¹J_PC= 28.9 Hz, PPhMe₂),

1

(m, 1 Fortho), -24.86 (m, 1 Fortho). ³¹P{ H} NMR (C₆D₆): d 11.81

97.53 (dd, ²J_FC= 36.6, 19.4 Hz, CH, m-C₆F₃H₂), 98.84 (dd, ²J_FC

=

(dm, ¹J_RhP= 137.4 Hz).

35.9, 23.0 Hz, CH, m-C₆F₃H₂), 106.10 (d, ⁴J_PC= 3.5 Hz, pzCH),

106.56 (s, pzCH), 106.82 (s, pzCH), 129.73 (s, PPhMe₂), 131.85

(dd, ¹J_PC= 9.9 Hz, ²J_RhC= 4.2 Hz, PPhMe₂), 138.58 (s, PPhMe₂),

For Tp¢Rh(2,5-C₆F₂H₃)H(PPhMe₂) (9g). Yield, 22.5 mg, 91%.

Colorless single crystals of 9g suitable for X-ray crystallographic

analysis were grown from hexane at -20 ^◦C. 9g: ¹H NMR (C₆D₆): d

–15.69 (ddd, ¹J_RhH= 20.4 Hz, ²J_PH= 26.9 Hz, ⁴J_FH= 11.2 Hz, 1H,

RhH), 1.29 (d, ²J_PH= 8.8 Hz, 3H, PPhMe₂), 1.65 (s, 3H, pzCH₃),

1.79 (s, 3H, pzCH₃), 1.82 (d, ²J_PH= 9.2 Hz, 3H, PPhMe₂), 1.91 (s,

3H, pzCH₃), 2.06 (s, 3H, pzCH₃), 2.22 (s, 3H, pzCH₃), 2.34 (s, 3H,

pzCH₃), 5.42 (s, 1H, pzH), 5.44 (s, 1H, pzH), 5.83 (s, 1H, pzH), 6.55

(m, 1H, C₆F₂H₃), 6.72 (m, 1H, C₆F₂H₃), 6.92 (m, 3H, PPhMe₂),

3

139.02 (s, PPhMe₂), 143.11 (d, J_PC= 2.6 Hz, pzCq), 143.29

(s, pzCq), 144.83 (s, pzCq), 149.96 (s, pzCq), 150.39 (s, pzCq),

151.38 (s, pzCq). Signals for the carbons of 2,4,6-C₆F₃H₂group

except for the meta carbons (CH) could not be assigned because of

1

multiple coupling with ﬂuorines. ¹⁹F{ H} NMR (C₆D₆): d -8.66

1

(m, 1 Fortho), -21.52 (m, 1 Fortho), -57.21 (m, 1 Fpara). ³¹P{ H}

1

NMR (C₆D₆): d 11.07 (dm, J_RhP= 133.5 Hz). Anal. Calcd for

1

6.93 (m, 1H, C₆F₂H₃), 7.65 (m, 2H, PPhMe₂). ¹³C{ H} NMR

C₂₉H₃₆BF₃N₆PRh: C, 51.96; H, 5.41; N, 12.54. Found: C, 51.69;

H, 5.33; N, 12.34.

(C₆D₆): d 12.75, 13.05, 13.17, 14.90, 16.21, 16.26 (s, pzCH₃), 18.27

(d, ¹J_PC= 30.5 Hz, PPhMe₂), 22.62 (dm, ¹J_PC= 35.2 Hz, PPhMe₂),

4

Tp¢Rh(2,3-C₆F₂H₃)H(PPhMe₂) (9e). Photolysis resulted in the

formation of 9e with the isomer Tp¢Rh(3,4-C₆F₂H₃)H(PPhMe₂),

106.47 (d, J_PC= 3.3 Hz, pzCH), 106.65 (s, pzCH), 107.52 (s,

pzCH), 109.87 (dd, ²J_FC= 24.4 Hz, ³J_FC= 9.2 Hz, CH, m-C₆F₂H₃),

10506 | Dalton Trans., 2010, 39, 10495–10509

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The Royal Society of Chemistry 2010

©

112.61 (dd, ²J_FC= 35.7 Hz, ³J_FC= 8.4 Hz, CH, p-C₆F₂H₃), 129.74

(s, PPhMe₂), 131.77 (dd, ¹J_PC= 10.2 Hz, ²J_RhC= 2.6 Hz, PPhMe₂),

X-ray data collection of the complexes, 1, 2-d₆, 3a, 3b, 3g, 5, 7, 9a,

9b, 9c, 9d, 9e and 9g

138.23 (s, PPhMe₂), 138.65 (s, PPhMe₂), 141.59 (dddd, br, ¹J_RhC

=

All crystals were placed onto the tip of a 0.1 mm diameter

glass capillary tube or ﬁber and mounted on a Bruker SMART

APEX II CCD Platform diffractometer for a data collection

at 100.0(1) K except for 9c (173(1) K).³⁴A preliminary set of

cell constants and an orientation matrix were calculated from

reﬂections harvested from three orthogonal wedges of reciprocal

space. The full data collection was carried out using Mo-Ka

radiation (graphite monochromator). The intensity data were cor-

rected for absorption.³⁵The structures were solved using SIR97³⁶

and reﬁned using SHELXL-97.³⁷Space groups were determined

based on systematic absences and intensity statistics. Except in

structures 3a and 3b, hydride and deuteride ligands were found

from the difference Fourier map, and their positions and isotropic

displacement parameters were reﬁned independently from those

of rhodium atoms. These are represented with thermal spheres

(50% or 30% probability density) in the ﬁgures. In structure 3a, the

position of the hydride ligand was reﬁned independently from that

of rhodium atom, but its isotropic displacement parameter was

reﬁned relatively (U_iso[H] = 2*U_eq[Rh]). Due to the severe disorder

in 3b, the hydride ligand was neither located nor placed; however,

it was included in the molecular formula. All other hydrogen

atoms were placed geometrically and reﬁned with relative isotropic

displacement parameters.

42.9 Hz, C, ipso-C₆F₂H₃), 143.21 (d, ³J_PC= 2.4 Hz, pzCq), 144.07

(s, pzCq), 144.52 (s, pzCq), 150.13 (s, pzCq), 150.77 (s, pzCq),

1

151.15 (s, pzCq), 157.85 (d, J_FC= 240.0 Hz, CF, m-C₆F₂H₃),

165.56 (d, ¹J_FC= 221.3 Hz, CF, o-C₆F₂H₃). The signal assignable

to the ortho CH of 2,5-C₆F₂H₃group was not detected probably

1

because of the overlap with solvent peaks. ¹⁹F{ H} NMR (C₆D₆): d

1

-27.25 (m, 1 Fortho), -60.36 (m, 1 Fmeta). ³¹P{ H} NMR (C₆D₆):

d 11.63 (ddd, ¹J_RhP= 140.3 Hz, ⁴J_FP= 16.3, 6.2 Hz). Anal. Calcd

for C₂₉H₃₇BF₂N₆PRh: C, 53.39; H, 5.72; N, 12.88. Found: C, 53.15;

H, 5.52; N, 12.65.

Tp¢Rh(2-C₆FH₄)H(PPhMe₂) (9h). Photolysis resulted in the

formation of 9h with the isomers Tp¢Rh(3-C₆FH₄)H(PPhMe₂)

1

and Tp¢Rh(4-C₆FH₄)H(PPhMe₂), and 7, as judged by H NMR

spectroscopy. Heating at 120 ^◦C for 1 h in C₆FH₅solution resulted

in the quantitative formation of 9h. Yield, 20.5 mg, 85%. Colorless

single crystals of 9h suitable for X-ray crystallographic analysis

were grown from hexane at -20 ^◦C. 9h: ¹H NMR (C₆D₆): d –15.79

(ddd, ¹J_RhH= 20.2 Hz, ²J_PH= 27.4 Hz, ⁴J_FH= 10.8 Hz, 1H, RhH),

2

1.35 (d, J_PH= 9.2 Hz, 3H, PPhMe₂), 1.67 (s, 3H, pzCH₃), 1.77

2

(s, 3H, pzCH₃), 1.88 (d, J_PH= 8.8 Hz, 3H, PPhMe₂), 1.92 (s,

3H, pzCH₃), 2.12 (s, 3H, pzCH₃), 2.23 (s, 3H, pzCH₃), 2.41 (s,

3H, pzCH₃), 5.45 (s, 1H, pzH), 5.46 (s, 1H, pzH), 5.87 (s, 1H,

pzH), 6.60 (m, 1H, C₆FH₄), 6.88 (m, 1H, C₆FH₄), 6.93 (m, 3H,

PPhMe₂), 6.97 (m, 1H, C₆FH₄), 7.19 (m, 1H, C₆FH₄), 7.70 (m,

Crystallographic data for 1

1

2H, PPhMe₂). ¹³C{ H} NMR (C₆D₆): d 12.76, 13.06, 13.21, 14.90,

16.30, 16.36 (s, pzCH₃), 18.53 (d, ¹J_PC= 30.2 Hz, PPhMe₂), 23.43

(dm, ¹J_PC= 29.9 Hz, PPhMe₂), 106.34 (d, ⁴J_PC= 3.3 Hz, pzCH),

106.59 (s, pzCH), 107.33 (s, pzCH), 112.76 (d, ²J_FC= 31.7 Hz, CH,

m-C₆FH₄), 122.30 (s, CH, m-C₆FH₄), 123.89 (d, ³J_FC= 8.1 Hz, CH,

C₁₈H₃₃BN₆PRh MW = 478.19; crystal system, Triclinic; space

¯

˚

group, P1; a = 10.0429(15), b = 11.5505(18) A, c = 11.6084(18) A;

◦

3

˚

a = 62.668(2) ; b = 80.643(3) ; g = 66.913(3) ; V = 1100.2(3) A ;

Z = 2; D_c= 1.443 Mg m^-3; m = 0.864 mm^-1; 24361 reﬂections

measured, 9947 unique (R(int) = 0.0315), 261 parameters, R₁(I >

2s(I)) = 0.0302; wR₂(all data) = 0.0762; GOF = 1.037.

p-C₆FH₄), 129.64 (s, PPhMe₂), 131.88 (dd, ¹J_PC= 10.1 Hz, ²J_RhC

=

1

2.7 Hz, PPhMe₂), 141.59 (dddd, br, J_RhC= 41.6 Hz, C, ipso-

C₆FH₄), 138.54 (s, PPhMe₂), 138.96 (s, PPhMe₂), 142.97 (d, ³J_PC

=

2.4 Hz, pzCq), 143.42 (d, ³J_FC= 14.0 Hz, CH, o-C₆FH₄), 143.80 (s,

Crystallographic data for 2-d₆

pzCq), 144.35 (s, pzCq), 150.25 (s, pzCq), 149.88 (s, pzCq), 151.08

C₂₄H₃₁BD₆N₆PRh MW = 560.32; crystal system, Monoclinic;

1

(s, pzCq), 169.62 (d, J_FC= 233.9 Hz, CF, o-C₆FH₄). ¹⁹F{ H}

˚

space group, Cc; a = 12.8303(11), b = 15.7867(13) A, c =

NMR (C₆D₆): d -19.86 (m, 1 Fortho). ³¹P{ H} NMR (C₆D₆): d

1

◦

˚

14.1339(17) A; a = 90 ; b = 111.057(1) ; g = 90 ; V =

1

12.06 (dm, J_RhP= 133.7 Hz). Anal. Calcd for C₂₉H₃₈BFN₆PRh:

2671.6(5) A ; Z = 4; D_c= 1.393 Mg m^-3; m = 0.722 mm^-1;

3

˚

C, 54.91; H, 6.04; N, 13.25. Found: C, 54.68; H, 5.96; N, 13.24.

32307 reﬂections measured, 14040 unique (R(int) = 0.0292), 315

parameters, R₁(I > 2s(I)) = 0.0272; wR₂(all data) = 0.0592;

GOF = 1.013.

Kinetics of reductive elimination reactions of Ar^FH from the

complexes 9a–e, 9g–h and 6

Crystallographic data for 3a·0.5(C₆H₁₄)

A resealable 5 mm NMR tube containing the complexes 9a–e,

9g–9h or 6 (6–8 mg) was charged with 0.7 mL of THF-d₈followed

by 0.5 mL of hexamethyldisiloxane added as an internal standard.

The sample was placed in a oil bath set to 120 ^◦C. NMR spectra

were recorded at regular intervals by ¹H NMR spectroscopy.

Kinetic analyses were performed by integration of the decreasing

hydride resonance relative to the signal for hexamethyldisilox-

ane. For all of the complexes, the eliminations did not go to

completion and were ﬁt to an approach to the equilibrium

using the KINSIM/FITSIM²⁹software package to determine

the rate constant of reductive elimination of the corresponding

ﬂuoroarenes. For compound 6, an Eyring plot was used to

extrapolate the rate of the reaction at 120 ^◦C using rate data taken

at 60, 70, 80, and 90 ^◦C (see Supporting Information‡).

C₂₇H₃₉BF₅N₆PRh MW = 687.33; crystal system, Monoclinic;

˚

space group, P2₁/n; a = 8.6504(13), b = 33.930(5) A, c =

◦

3

˚

20.878(3) A; a = 90 ; b = 100.671(2) ; g = 90 ; V = 6021.8(15) A ;

Z = 8; D_c= 1.516 Mg m^-3; m = 0.680 mm^-1; 74170 reﬂections

measured, 12307 unique (R(int) = 0.1197), 787 parameters, R₁(I >

2s(I)) = 0.0802; wR₂(all data) = 0.1985; GOF = 1.051.

Crystallographic data for 3b

C₂₄H₃₃BF₄N₆PRh MW = 626.25; crystal system, Orthorhombic;

˚

space group, Pca2₁; a = 29.063(3), b = 10.5847(12) A, c =

3

˚

17.7982(19) A; V = 5475.0(10) A ; Z = 8; D_c= 1.520 Mg

m^-3; m = 0.735 mm^-1; 117833 reﬂections measured, 26396 unique

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The Royal Society of Chemistry 2010

Dalton Trans., 2010, 39, 10495–10509 | 10507

©

(R(int) = 0.1168), 906 parameters, R₁(I > 2s(I)) = 0.0646; wR₂

(all data) = 0.1464; GOF = 1.014.

64752 reﬂections measured, 18391 unique (R(int) = 0.0362), 447

parameters, R₁(I > 2s(I)) = 0.0326; wR₂(all data) = 0.0849;

GOF = 1.040.

Structure description for 3b

Crystallographic data for 9c

The structure is the one suggested. There are two molecules

in the asymmetric unit, both which are modeled as disordered

over two positions. Initially each molecular disorder was reﬁned

independently, but it was found that the 85 : 15 component ratio

resulted for both. Upon further examination, it was plain that the

disorders had to be reﬁned together to avoid close intermolecular

contacts. The two positions of molecule one (Rh1) had only the

rhodium atom in common, whereas the all atoms of molecule

two (Rh2, Rh2¢) were in different positions. In both cases, the two

components were related by a pseudo-mirror (the disorder ratio of

85 : 15 disallows the reﬁnement in a centrosymmetric space group).

C₂₉H₃₅BF₄N₆PRh MW = 688.32; crystal system, Monoclinic;

˚

space group, P2₁/n; a = 11.9400(8), b = 18.7449(13) A, c =

◦

˚

14.5298(10) A; a = 90 ; b = 109.712(1) ; g = 90 ; V =

3061.4(4) A ; Z = 4; D_c= 1.493 Mg m^-3; m = 0.664 mm^-1;

3

˚

74523 reﬂections measured, 16316 unique (R(int) = 0.0421), 391

parameters, R₁(I > 2s(I)) = 0.0427; wR₂(all data) = 0.1209;

GOF = 0.996.

Crystallographic data for 9d

C₂₉H₃₆BF₃N₆PRh MW = 670.33; crystal system, Triclinic; space

¯

˚

group, P1; a = 10.2916(14), b = 11.5263(16) A, c = 12.4406(17) A;

Crystallographic data for 3g

◦

3

˚

a = 90.743(2) ; b = 93.433(2) ; g = 92.065(2) ; V = 1472.0(3) A ;

Z = 2; D_c= 1.512 Mg m^-3; m = 0.684 mm^-1; 34212 reﬂections

measured, 13969 unique (R(int) = 0.0365), 382 parameters, R₁(I >

2s(I)) = 0.0332; wR₂(all data) = 0.0830; GOF = 1.045.

C₂₄H₃₅BF₂N₆PRh MW = 590.27; crystal system, Monoclinic;

˚

space group, P2₁/c; a = 10.4449(16), b = 14.597(2) A, c =

◦

3

˚

17.499(3) A; a = 90 ; b = 92.021(3) ; g = 90 ; V = 266.4(7) A ;

Z = 4; D_c= 1.470 Mg m^-3; m = 0.739 mm^-1; 42567 reﬂections

measured, 8144 unique (R(int) = 0.1125), 332 parameters, R₁(I >

2s(I)) = 0.0488; wR₂(all data) = 0.1167; GOF = 0.995.

Crystallographic data for 9e

C₂₉H₃₇BF₂N₆PRh MW = 652.34; crystal system, Triclinic; space

¯

˚

group, P1; a = 10.2523(9), b = 11.6983(10) A, c = 12.3627(11) A;

◦

3

Crystallographic data for 5

˚

a = 92.716(2) ; b = 95.959(2) ; g = 92.041(2) ; V = 1471.8(2) A ;

Z = 2; D_c= 1.472 Mg m^-3; m = 0.677 mm^-1; 26065 reﬂections

measured, 9759 unique (R(int) = 0.0961), 373 parameters, R₁(I >

2s(I)) = 0.0568; wR₂(all data) = 0.1230; GOF = 0.968.

C₂₃H₃₅BN₆PRh MW = 540.26; crystal system, Monoclinic;

˚

space group, P2₁/c; a = 11.4148(12), b = 15.6111(16) A, c =

◦

˚

14.8282(15) A; a = 90 ; b = 107.784(2) ; g = 90 ; V =

2516.1(4) A ; Z = 4; D_c= 1.426 Mg m^-3; m = 0.765 mm^-1;

3

˚

Crystallographic data for 9g

60723 reﬂections measured, 13296 unique (R(int) = 0.0989), 305

parameters, R₁(I > 2s(I)) = 0.0499; wR₂(all data) = 0.1064;

GOF = 0.993.

C₂₉H₃₇BF₂N₆PRh MW = 652.34; crystal system, Triclinic; space

¯

˚

group, P1; a = 10.1914(10), b = 10.5164(11) A, c = 15.794(2) A;

◦

3

˚

a = 99.310(2) ; b = 99.180(2) ; g = 115.370(2) ; V = 1458.8(3) A ;

Z = 2; D_c= 1.485 Mg m^-3; m = 0.683 mm^-1; 39002 reﬂections

measured, 13918 unique (R(int) = 0.0391), 373 parameters, R₁(I >

2s(I)) = 0.0401; wR₂(all data) = 0.1029; GOF = 1.038.

Crystallographic data for 7

C₂₃H₃₃BN₆PRh MW = 538.24; crystal system, Monoclinic; space

˚

group, P2₁/n; a = 13.600(4), b = 12.888(4) A, c = 14.424(4) A;

◦

3

˚

a = 90 ; b = 103.895(4) ; g = 90 ; V = 2454.0(12) A ; Z = 4;

D_c= 1.457 Mg m^-3; m = 0.784 mm^-1; 42160 reﬂections measured,

8821 unique (R(int) = 0.1047), 301 parameters, R₁(I > 2s(I)) =

0.0776; wR₂(all data) = 0.1888; GOF = 1.127.

Computational details

All calculations were performed with the Gaussian03 package³⁸of

programs with the hybrid B3PW91 functional.^39,40The Rh atom

was represented by the relativistic effective core potential (RECP)

from the Stuttgart group and the associated basis set,⁴¹augmented

by an f polarization function.⁴²The phosphorus atom was treated

with Dolg pseudopotential and the associated basis set⁴³plus a d

polarization function.⁴⁴The remaining atoms (C, H, N, B, F) were

represented by a 6-31G(d,p) basis set.⁴⁵Full optimization of geom-

etry was performed without any constraint, followed by analytical

computation of the Hessian matrix to identify the nature of the lo-

cated extrema as minima. See Supporting Information for details.‡

Crystallographic data for 9a

C₃₅H₄₈BF₅N₆PRh MW = 792.48; crystal system, Triclinic; space

¯

˚

group, P1; a = 10.2069(10), b = 13.0730(13) A, c = 15.3042(15) A;

a = 105.613(2)^◦; b = 108.235(2)^◦; g = 101.547(2)^◦; V =

1775.4(3) A ; Z = 2; D_c= 1.482 Mg m^-3; m = 0.587 mm^-1;

3

˚

41158 reﬂections measured, 16867 unique (R(int) = 0.0277), 400

parameters, R₁(I > 2s(I)) = 0.0286; wR₂(all data) = 0.0742;

GOF = 1.057.

Acknowledgements

Crystallographic data for 9b·C₆H₁₄

C₃₅H₄₉BF₄N₆PRh MW = 774.49; crystal system, Triclinic; space

We would like to acknowledge the U.S. Department of Energy

Sciences (FG02-86ER13569) for their support of this work.

T.T. thanks the Japanese Society for Promotion of Science for

a postdoctoral fellowship. OE and EC thank the CNRS and

¯

˚

group, P1; a = 10.2654(11), b = 13.2828(14) A, c = 15.0471(16) A;

a = 106.173(2)^◦; b = 107.854(2)^◦; g = 101.522(2)^◦; V =

3

1782.1(3) A ; Z = 2; D_c= 1.443 Mg m^-3; m = 0.579 mm^-1;

˚

10508 | Dalton Trans., 2010, 39, 10495–10509

This journal is

The Royal Society of Chemistry 2010

©

the Ministe`re de l’Education Supe´rieure et de la Recherche for

funding. We also that Prof. Robin Perutz for early suggesting

regarding the value of making these quantitative measurements.

17 L.-C. Campeau and K. Fagnou, Chem. Commun., 2006, 1253; M.

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18 Calculations on osmium and rhodium complexes showed that the

barrier to oxidative addition of the C–F bond is ~24 kcalmol^-1higher

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19 E. Clot, M. Besora, F. Maseras, C. Me´gret, O. Eisenstein, B. Oelckers

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20 L. Cronin, C. L. Higgitt, R. Karch and R. N. Perutz, Organometallics,

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Article Doi

Synthesis, structure, and reductive elimination in the series Tp′Rh(PR3)(ArF)H; Determination of rhodium-carbon bond energies of fluoroaryl substituents

DOI: 10.1039/c0dt00157k

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Full text of DOI:10.1039/c0dt00157k

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