Interactions of cationic palladium(II)- and platinum(II)-η3- allyl complexes with fluoride: Is asymmetric allylic fluorination a viable reaction?

FULL PAPER

DOI: 10.1002/ejic.200500795

Interactions of Cationic Palladium(II)- and Platinum(II)-η³-Allyl Complexes

with Fluoride: Is Asymmetric Allylic Fluorination a Viable Reaction?

Lukas Hintermann,*^[a,b]Florian Läng,^[a]Pascal Maire,^[a]and Antonio Togni^[a]

Keywords: Palladium / Platinum / Allyl ligands / Fluorination / Naked fluoride

The complex cations [M(η³-R₂All)(PPFPz{3-tBu})]⁺(M = Pd^II,

R₂All = 1,3-diphenylallyl, 1,3-dicyclohexylallyl, indenyl; M =

Pt^II, R₂All = 1,3-diphenylallyl; PPFPz-{3-tBu} = 3-tert-butyl-

1-{1-[2-diphenylphosphanyl-ferrocenyl]ethyl}-1H-pyrazole)

Me₄NF to give [Pt(1,3-Ph₂C₃H₃)(PPFPz{3-tBu})]F which ex-

isted as a mixture of interconverting allyl isomers in solution

at ambient temperature. For the bromide salt, [Pt(η³-1,3-

Ph₂C₃H₃)(PPFPz{3-tBu})]Br, allyl isomerization was slow at

ambient temperature. Precursors of Pt⁰reacted with bromo-

1,3-diphenylprop-2-ene to give [Pt₂(µ-Br)₂(η³-1,3-Ph₂All)₂]

and precursors of Pd⁰underwent oxidative additions with

bromo- and fluoro-1,3-diphenyl-2-propene to give 1,3-di-

–

have been prepared as salts with PF₆or SbF₆^–. They have

been characterized by NMR spectroscopy in solution and by

X-ray crystallography in the solid state. Their reactions with

sources of nucleophilic and “naked” fluoride have been in-

vestigated by multinuclear NMR spectroscopy. The Pd^IIcom- phenylallyl complexes of Pd^II. Therefore, the nucleophilic at-

plexes did not undergo any nucleophilic substitution with

concomitant release of allyl fluorides. The dicyclohexylallyl

fragment was released as a 1,3-diene by elimination, but

with other allyl complexes nonspecific decomposition reac-

tions predominated. The complex [Pt(η³-1,3-Ph₂C₃H₃)-

(PPFPz{3-tBu})]PF₆underwent an anion exchange with

tack of fluoride on the allyl fragment of Pd^IIcomplexes is

endergonic, and the high energy barrier of this step is diffi-

cult to overcome in a catalytic allylic fluorination reaction.

Germany, 2006)

industry is considered. Here, selectively fluorinated organic

compounds are in high demand for diverse applications.^[13]

In response to this situation, we have initiated a research

program directed towards transition-metal catalyzed selec-

tive fluorination reactions at sp³centers. This has already

resulted in a fluoro-Ru^II-complex-mediated halogen ex-

change reaction^[14]and a titanium-catalyzed asymmetric

catalytic α fluorination of β-keto esters.^[15]Similar asym-

metric fluorinations have been discovered by us and others

using Pd^II,^[16]Cu^II,^[17–19]Ni^II,^[18,20]and Ru^II[21]complexes

as catalysts, all of them relying on electrophilic fluorination

reagents. The present work involves a promising alternative

strategy for asymmetric catalytic fluorination using fluoride

nucleophiles. We were inspired by the observation that cata-

lytic allylic substitution reactions enable the attachment of

a variety of nucleophiles at allylic fragments with high

enantioselectivity.^[22]Consequently, we hoped to realize a

palladium catalyzed allylic fluorination reaction starting

from suitable allylic substrates and fluoride nucleophiles

using chiral Pd^IIcomplexes as catalysts.^[23]Since cationic

η³-allyl complexes of palladium() are well-established in-

termediates in asymmetric allylic substitution reactions,^[24]

we also wanted to investigate the interaction of such species

with fluoride anions in order to clarify: (a) if nucleophilic

attack of fluoride takes place; or (b) what other interactions

(coordination, ion-pairing etc.) play a role. Analogous ex-

periments with platinum() complexes were also planned

Introduction

The organometallic and coordination chemistry of fluo-

ride and the C–F bond have recently received much atten-

tion. Initial work centered around transition-metal fluoro

complexes,^[1–3]the coordination ability of the notoriously

inert C–F bond^[4]and its cleavage by means of electron-rich

transition-metal centers using either stoichiometric^[5]or

catalytic methods.^[6]Furthermore, “fluoride effects” have

been discovered in homogeneous catalysis, which points to

an important role of fluoride as a steering ligand in transi-

tion-metal-catalyzed reactions.^[7,8]By contrast, the metal-

catalyzed generation of C–F bonds (i.e. catalytic fluorina-

tion of organic compounds) has long been limited to indus-

trial applications of the Swarts reaction^[9]and some exam-

ples of the Pd-catalyzed fluorocarbonylations.^[10,11]Re-

search on the generation of fluoroarenes by reductive elimi-

nations from aryl-fluoropalladium() complexes is actively

pursued but not yet realized.^[12]The neglect of transition-

metal mediated fluorination methodologies comes as a sur-

prise when the importance of fluorinated organic com-

pounds in the chemical, agricultural, and pharmaceutical

[a] Laboratory of Inorganic Chemistry, Swiss Federal Institute of

Technology, ETH Hönggerberg, HCI,

8093 Zürich, Switzerland

[b] Institute of Organic Chemistry, RWTH Aachen University,

Landoltweg 1, 52074 Aachen, Germany

E-mail: lukas.hintermann@oc.rwth-aachen.de

Eur. J. Inorg. Chem. 2006, 1397–1412

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L. Hintermann, F. Läng, P. Maire, A. Togni

FULL PAPER

because the slower kinetics of Pt^IIrelative to Pd^IIcom- fluoride is reduced by solvation in protic media or in the

pounds should allow for the observation of short-lived in- presence of trace water.^[33]It should be noted that more

termediates with the added advantage of having ¹⁹⁵Pt NMR traditional fluoride sources (such as KF, CsF, or NBu₄F)

spectroscopy as a selective analytical tool.^[25]Finally, we are either insoluble in nonprotic solvents or cannot be dried

also hoped to clarify the issue of a “fluoride-effect” that we without decomposition.^[34]

had observed earlier in the asymmetric amination of ethyl

1,3-diphenylallyl carbonate (1) catalyzed by Pd^IIwith li-

gand 2a (Scheme 1). The reaction gives the amination prod-

uct 3 in either very high or low enantioselectivity, de-

–

pending on the counterion (F^–or PF₆) of the ammonium

salt additive.^[8]

Scheme 2. Nucleophilic allylic fluorination of palladium complexes.

(a) Attempted, but unsuccessful allylic fluorination with a Pd⁰cata-

lyst. (b) The nucleophilic attack of fluoride on cationic allylpalladi-

um() complexes is the key step in a postulated allylic fluorination

reaction, as investigated in this work.

Scheme 1. The palladium-catalyzed asymmetric allylic amination is

Analysis of reaction solutions from catalysis experiments

using ¹⁹F NMR spectroscopy did not show signals corre-

sponding to 1,3-diphenylallyl fluoride (6),^[14a,35]or any

other organofluorine compound. Straightforward allylic

fluorination in a catalytic manner is thus not feasible. We

therefore proceeded to study the stoichiometric variant of

this reaction, namely the attack of fluoride on isolated,

fully-characterized cationic η³-palladium() and -plati-

num() complexes (Scheme 2, b).

subject to astonishing anion effects on enantioselectivity.^[8]dba =

dibenzylidene acetone, Bn = benzyl.

Results

The new phosphanyl-ferrocenyl pyrazole 2b, (PPFPz-

{3-tBu}, 3-tert-butyl-1-{(R)-1-[2-(S_P)-diphenylphosphanyl-

ferrocenyl]ethyl}-1H-pyrazole), (Scheme 1) was prepared

from 3(5)-tert-butylpyrazole^[26]and (R,S)-PPFA^[27](PPFA

=

N,N-dimethyl-1-[2-diphenylphosphanyl-ferrocenyl]ethyl-

Synthesis and Structure of Allylpalladium(II) and

-platinum(II) Complexes

amine) in high yield as a single regioisomer according to

our standard method.^[28]A test run with 2b as the ligand

in the palladium-catalyzed allylic amination reaction,^[29]

Several cationic palladium() allyl complexes incorporat-

shown in Scheme 1, using cocatalytic NBu₄F·3H₂O ing the ligand 2b, (PPFPz-{3-tBu}), were synthesized in the

(3 equiv. relative to [Pd]),^[8]gave the amination product (S)- usual manner^[36]by reaction with the dinuclear allylpalladi-

3 with an ee Ͼ 99.5%. Thus, 2a and 2b behaved identically um() chlorides (7) followed by halide abstraction with

in this reaction, but 2b was the preferred ligand for mechan- either TlPF₆, AgSbF₆, or (Et₃O)BF₄(Scheme 3 and

istic studies because of the simplicity of the ¹H NMR-signal Scheme 5). In some cases, we applied a new halide abstrac-

of the tert-butyl group over the adamantyl group. Using tion technique that relies on the combination of epichlo-

similar reaction conditions, we next attempted to perform rohydrine (or any other reactive epoxide) with an acid and

catalytic allylic fluorination reactions with carbonate 1 a nonnucleophilic counterion, such as HPF₆. This method

(Scheme 2, a). The catalyst was generated in situ from relies on the ability of epoxides to scavenge halide anions

Pd(dba)₂and 2b. The sources of nucleophilic fluoride that by nucleophilic-ring opening.

were tested are TBAT {NBu₄[SiF₂Ph₃] (4)},^[30]a nucleo-

The diphenylallyl complex 8a occurs predominantly as

philic non-basic fluoride transfer reagent, and Me₄NF the exo-syn-syn isomer^[37](Ͼ98% by ³¹P NMR spec-

(5),^[31]a “naked” fluoride^[32]of high basicity. Anhydrous troscopy) in CDCl₃solution, in agreement with observa-

versions of these reagents are available and they also show tions on complexes with similar ligands.^[29]The same iso-

considerable solubility in nonprotic organic solvents, which mer is also present in the solid state, as shown by X-ray

is an important characteristic because the nucleophilicity of crystallography (vide infra, Figure 7). η³-1,3-Dicyclohex-

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Cationic Palladium()- and Platinum()-η³-Allyl Complexes with Fluoride

FULL PAPER

NMR spectroscopic shifts (Table 1) were assigned to the C_S

symmetric isomer A, which has two sets of allylic protons,

and the C_2vsymmetric isomer B (Figure 1). Interchange of

A and AЈ was relatively slow up to a temperature of 273 K.

Interchange of A with B was slow over the whole tempera-

ture range studied (253–298 K), but notable line broadening

occurred at 298 K. The allyl units had the syn-syn configu-

ration in both A and B, as deduced from the coupling [³J_H,H

= 11 Hz] between the central and terminal allyl protons.

Scheme 3. Synthesis of cationic allylpalladium() complexes. (a) 2b,

halide abstracting reagent (see Exp. Section). 8a: 87%; 8b: 96%; 8c:

82%. Cy = cyclohexyl.

Table 1. ¹H NMR spectroscopic data for allyl hydrogen atoms

within the conformational isomers of 13 at 253 K.

Conformer

Central H

anti H

A

5.39 ppm, t, J = 11.1 3.48 ppm, dd, J = 10.9, 5.1

5.06 ppm, t, J = 11.1 3.71 ppm, dd, J = 10.9, 7.5

5.42 ppm, t, J = 11.1 3.43 ppm, dd, J = 11.0, 5.7

ylallyl complexes of palladium() are new. Our synthetic

route (Scheme 4) started with an aldol addition of cyclo-

hexyl methyl ketone (9) followed by elimination to the α,β-

unsatuarated ketone and Luche reduction^[38]to give dicy-

clohexylallyl alcohol (10). Fluorination with DAST [(dieth-

ylamino)sulfur() trifluoride]^[39]produced a reference sam-

ple of allyl fluoride 11. According to a general procedure

by Vitagliano et al.,^[40]allyl trifluoroacetate (12) was treated

with Pd(dba)₂by oxidative addition to give the trifluo-

roacetate-bridged dimer 13, and this complex underwent li-

gand exchange with LiCl to give the chloro-bridged dimer

7b. Alternatively, and more conveniently, the last two steps

could be performed in a single synthetic operation (12Ǟ7b).

B

Scheme 4. Synthesis of (1,3-dicyclohexylallyl)palladium() com-

plexes. (a) 1. LDA, THF, –78 °C; 2. CyCHO; 3. MsCl. (b) DBU,

Me₂CO; 70% (from 9). (c) NaBH₄, CeCl₃·7H₂O, MeOH, room

temp.; 77%. (d) DAST, CH₂Cl₂, –78 °C; quant. (e) TFAA, Py, 0 °C;

93%. (f) Pd(dba)₂, THF/MeCN (3:1), 40 °C; 93%.·(g) Pd(dba)₂,

LiCl, THF/MeCN (3:1); 97%. (h) LiCl. LDA = lithium diisopro-

pylamide, DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene, TFAA = tri-

fluoroacetic acid anhydride.

1

Figure 1. Conformational isomerism and VT H NMR spectra of

13 (CDCl₃, 300 MHz). (a) Conformational isomerism and dynamic

behavior of 13. (b) VT-NMR: Signals of A/AЈ and B (compare in

Table 1) are partially overlapping at all temperatures; the virtual

quartet at 233 and 253 K is a superimposition of two triplets. At

298 K, the interconversion of A and AЈ approaches coalescence.

Other processes such as conformational changes of the Cy substitu-

The bridged trifluoroacetate 13 showed interesting con-

formational isomerism in solution, similar to that reported

for [Pd₂(µ-OAc)₂(η³-R₂All)₂] complexes.^[41]The VT ¹H ents presumably add to the dynamics.

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L. Hintermann, F. Läng, P. Maire, A. Togni

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Incorporation of the (1,3-dicyclohexylallyl)palladium()

fragment into a cationic complex with ligand 2b (Scheme 3)

yielded 8b, initially as an 82:18 mixture of two allyl isomers.

This ratio changed to about 1:1 (52:48) after recrystalli-

1

zation from hot methanol. On the basis of the H NMR

coupling data, the syn-syn configuration was assigned to

the main isomer, and the syn-anti (anti Cy group trans to N)

configuration to the minor isomer, but the one-dimensional

analysis did not give conclusive information about the endo

or exo orientation. An X-ray crystal structure of 8b sup-

ported the NMR spectroscopic assignment in a surprising

way: the complex had crystallized as a statistical 1:1 mix-

ture of allyl isomers possessing the exo-syn-syn and endo-

anti-syn (anti trans to N) configurations, respectively (Fig-

ure 2). Apparently, both isomeric dicyclohexylallyl frag-

ments had flexibly adapted to the coordination environ-

ment of the metal-ligand framework (Figure 2, A and B),

which was kept as a common unit during the refinement

of the structure. The bonding data for the dicyclohexylallyl

fragments are not very accurate because of the disorder and

will not be discussed.

Figure 3. ORTEP plot (30% probability ellipsoids) of 8c·CH₂Cl₂.

Hydrogen atoms, CH₂Cl₂, and SbF₆anion are omitted for clarity.

Selected bond lengths [Å] and angles [°]: Pd–P = 2.303(2), Pd–N(2)

= 2.122(6), Pd–C(27) = 2.191(8), Pd–C(28) = 2.225(9), Pd–C(29) =

2.260(10), Pd–C(30) = 2.570(9), Pd–C(35) = 2.576(8), C(27)–C(28)

= 1.397(14), C(27)–C(35) = 1.460(13), C(28)–C(29) = 1.424(17),

C(29)–C(30) = 1.421(17), C(30)–C(35) = 1.431(12); N(2)–Pd–P(1)

= 92.32(18), C(27)–C(28)–C(29) = 106.4(10).

mide (15)^[47]to a Karstedt complex solution (16)^[48,49]read-

ily produces a yellow precipitate of the allylplatinum() bro-

[50]

mide (17) (Scheme 5). Pt₂(dba)₃also underwent this oxi-

dative addition, but the resulting product was less pure due

to metallic platinum residues in the precursor complex. Re-

action of 17 with 2b gave the complex 18·Br, which was

converted to 18·PF₆using the new HPF₆/epichlorohydrine

reagent (Scheme 5).

Figure 2. ORTEP representations (30% probability ellipsoids) of

cationic fragments displaying configurational allyl isomerism in the

solid-state structure of 8b. PF₆anions and hydrogen atoms are

omitted for clarity, carbon atoms within the dicyclohexylallyl frag-

ments are filled in as grey. A: endo-syn-anti isomer; B: exo-syn-syn

isomer. Selected bond lengths [Å] and angles [°]: Pd–N(2) =

2.143(6), Pd–P 2.325(2); N(2)–Pd–P = 89.16(18). As a result of the

disorder, values for the allyl fragments are not accurate.

The dark-red indenyl complex 8c was prepared from

{PdCl(Ind)}_n(7c)^[42]in the usual way (Scheme 3). Unlike

most other cationic complexes described here, the indenyl

compound was somewhat air-sensitive, with solutions of it

slowly decomposing in air. A mixture of exo and endo iso-

mers was present in solution, with exo-8c as the major spe-

cies, as shown by H,H NOESY cross peaks of the central

allyl hydrogen and the tert-butyl group. In the solid state

only the exo isomer is present (Figure 3). The X-ray crystal

structure also shows that the indenyl fragment is η³-

bonded, rather than η⁵.

Unlike the much studied (1,3-diphenylallyl)palladium()

Scheme 5. Synthesis of (1,3-diphenylallyl)platinum() complexes.

(a) PhCH=CHCH(Br)Ph (15), tBuOMe, 0 °C; 77%. (b) 2b, THF;

complexes,^[29,43,44]the corresponding platinum compounds

are unknown, even though platinum-catalyzed allylic alky- 97%. (c) 1. epichlorohydrine, HPF₆, Me₂CO; 2. crystallization from

CH₂Cl₂/MeOH; 73% (from 17).

lation (including that of 1,3-diphenylallyl substrates) has

been studied and the intermediacy of cationic η³-allyl com-

plexes have been invoked in analogy to Pd chemistry.^[45,46]

Comparative spectroscopic data for the platinum com-

We have found that the addition of 1,3-diphenylallyl bro- pounds was collected from a range of reference complexes

1400

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Cationic Palladium()- and Platinum()-η³-Allyl Complexes with Fluoride

FULL PAPER

whose synthesis is displayed in Scheme 6. Pregosin’s bis- lic OH group is presumably involved in a weak hydrogen

(styrene)platinum() chloride^[51]served as the most suitable bond with the electron-rich Pt^IIcenter.^[52]The phenol is ar-

precursor for dichloro complex 19 under mild conditions. ranged with the OH group pointing towards the Pt center

The diphenyl complex 20 resulted from reaction of 19 with and the O–Pt distance is 4.21 Å. By comparison, O–Pd dis-

excess Grignard reagent. Interestingly, the substance crys- tances of 3.2–3.7 Å have been observed for related interac-

tallized with one equivalent of phenol, which originated tions between Pd⁰and aliphatic alcohols.^[53]

from a partially oxidized PhMgBr solution. The X-ray crys-

The fluoro complex 21 was obtained in situ in an NMR

tal structure of 20·PhOH is shown in Figure 4. The pheno- tube by protonolysis of the diphenylplatinum complex 20

with NEt₃·(HF)₃. Only one bond was cleaved even though

an excess of reagent was added. The presence of a Pt–F

bond in this complex is evident from the coupling patterns

in the ¹⁹F NMR spectrum (doublet with platinum satellites)

and the ³¹P NMR spectrum (doublet with platinum satel-

lites) (Figure 5). Any complex containing a covalent Pt–F

bond in our study would have similar NMR characteristics,

whereas ionic Pt⁺/F^–interactions would not be expected to

result in such ¹⁹F NMR signals or coupling characteristics.

Figure 5. NMR spectra of fluoro complex 21. (a) ¹⁹F NMR

(282.4 MHz, CDCl₃), the signal at δ = –214.6 ppm (²J_P,F= 207,

¹J_Pt,F= 210 Hz) is due to the platinum bound fluoro ligand. (b) ³¹

P

NMR (121.5 MHz, CDCl₃), the signal at δ = –11.8 ppm (d, J_P,F

=

207, J_Pt,P= 5104 Hz) is due to the fluoro complex, while the signal

at δ = –9.6 ppm (s, J_Pt,P= 5107 Hz) belongs to an unidentified side

product.

Scheme 6. Syntheses of platinum() complexes incorporating li-

gand 2b and/or an allyl ligand.

The allyl complex 22 and the methallyl derivative 23 were

obtained by the usual method (Scheme 6, b). They formed

equilibrium mixtures of exo and endo isomers in solution,

with the larger methallyl group inducing a slightly higher

amount of the exo isomer (Table 2).

Solution Structure of (1,3-Diphenylallyl)platinum(II

)

Complexes

The η³-allyl complex 18·PF₆occurs predominantly as the

exo-syn-syn isomer in either [D₈]THF or CDCl₃solution in

the same manner as its Pd-counterpart 8a (Figure 6).

In contrast, the bromide 18·Br exists as a mixture of four

main isomers in CDCl₃solution (Table 2) and the isomeric

ratio remained unchanged on refluxing a solution of the

complex in toluene. The allyl isomers of 18·Br could be of

the cationic η³-type (eight possible diastereomers) or the

neutral η¹-type with coordinated bromide (four possible

diastereomers), or mixtures thereof. The J_Pt,Pcoupling con-

stants of the 18·Br isomers were in the range of 4700 to

5100 Hz (Table 2), which is close to the value for the η³-

allyl complex 18·PF₆, but rather high compared to the value

of [PtBr₂(2a)].^[55]The low frequency ¹⁹⁵Pt NMR chemical

shifts of 18·Br also point towards a cationic η³-configura-

tion. However, the most important notion is that the nature

Figure 4. ORTEP plot (50% probability ellipsoids) of 20·PhOH.

Hydrogen atoms are omitted for clarity. Selected bond lengths [Å]

and angles [°]: Pt–P = 2.33(2), Pt–N(2) = 2.18(5), Pt–C(27) =

1.97(5), Pt–C(33) = 2.08(3); P–Pt–N(2) = 88.7(16), C(27)–Pt–C(33)

= 86.8(19), P–Pt–C(27) = 93.1(12), P–Pt–C(33) = 175.4(5), N(2)–

Pt–C(33) = 91.8(13), N(2)–Pt–C(27) = 174.6(9).

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L. Hintermann, F. Läng, P. Maire, A. Togni

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Table 2. NMR data and isomer equilibrium composition of the platinum complexes. ³¹P NMR spectroscopy at 101.3 or 121.5 MHz, ¹⁹⁵Pt

NMR spectroscopy at 64.3 or 86 MHz. All data at room temp. in CDCl₃, besides 18·PF₆([D₈]THF), 18·F ([D₈]toluene at 213 K).

Complex

Isomer

Abundance

³¹P NMR

[δ/ppm]

¹⁹⁵Pt NMR

[δ/ppm]

J_Pt,P

[Hz]

18·PF₆

18·Br

exo

A

Ͼ98%

12%

20%

44%

23%

7%

10.4

7.5

9.2

12.6

13.5

1.1

1.8

3.1

7.5

10.7

12.5

12.6

11.5

11.9

44.7

–16.1

–14.6

5.3

–4453

–4565

–4790

–4897

–4903

n.d.

–5521

–3700

n.d.

5029

5056

4697

5130

4760

3903

3890

4098

3925

3818

4413

n.d.

4291

4010

3847

3783

3713

1688

5104

B

C

D

18·F

A

B

9%

C

17%

63%

5%

78%

22%

81%

19%

100%

–

D

E

[Pt(η³-C₃H₅)(2b)]PF₆(22)

[Pt(η³-C₄H₇)(2b)]PF₆(23)

exo

endo

exo

endo

[Pt(Ph₂All)(dppe)]PF₆(24)

[PtCl₂(2b)] (19)

[PtBr₂(2a)]^[a]

–

[PtPh₂(2b)] (20)

[Pt(Ph)F(2b)] (21)^[b]

–11.8

1

2

[54]

[a] Ref.^[55][b] F is trans to P, deduced from the large values of J_Pt,Por J_P,F

.

C(27)–Pt/Pd–C(29)] out of the coordination plane is 14°.

This numerical value serves as a measure of the asymmetry

induced on the allyl fragment by the chiral ligand.^[29]The

³¹P NMR chemical shifts of 8a and 18·PF₆also match

closely (Table 2). These results justify, once more, the ap-

proach of using kinetically more inert platinum complexes

as analogs for the corresponding palladium species in mech-

anistic research. In fact, 18·PF₆is also a catalyst for the

allylic alkylation of ethyl 1,3-diphenylallyl carbonate (1)

with dimethyl malonate, giving the product of allylic alky-

lation in 74% ee in a slow reaction,^[56,65]whereas analogous

Pd complexes (with ligand 2a) react much faster to give the

alkylation product in 91% ee.^[55]Asymmetric allylic alky-

lation of 1,3-diphenylallyl substrates using Pt complexes has

been studied in detail by Williams and coworkers.^[46]

Another example of a cationic (1,3-diphenylallyl)plati-

num() complex is the DIPHOS derivative 24, which was

also structurally characterized as the syn-syn isomer in both

the CD₂Cl₂solution and in the solid state (Figure 7, c). The

bite angle P–Pt–P in this complex is 86.4° instead of the

94.5° for 18·PF₆. The interplane angle defined by C(1)–

C(2)–C(3)/P(1)–Pt–P(2) is 67° in this complex and the rota-

tion of the allyl fragment vector normal plane (approxi-

mated by C(1)–Pt–C(3)), out of the idealized perpendicular-

ity to the coordination plane [defined by P(1)–Pt–P(2)], is

only 1°, a very low value despite the local chiral C₂sym-

metry that the DIPHOS ligand adopts in its solid-state con-

formation.

Figure 6. ¹⁹⁵Pt,¹H HMQC of 18·PF₆in [D₈]THF. The crosspeaks

1

lie below the positions of the ¹⁹⁵Pt satellites in the H NMR spec-

trum and are split vertically into a doublet (J_Pt,P= 5030 Hz). In-

tense crosspeaks are observed for allylic protons (δ = 4.9, 5.9, and

6.9 ppm), whereas weaker coupling is observed with two sets of

ortho-hydrogen atoms of phenyl groups (δ = 6.4, 7.4 ppm) and with

the pyrazole hydrogen 4-H at 8.0 ppm.

of the anion directly and strongly influences the equilibrium

composition of the allyl isomer mixture.

Solid-State Structures of (1,3-Diphenylallyl)platinum(II

)

Complexes

Crystals of 18·PF₆were easily obtained and the result of

the X-ray structural analysis is shown in Figure 7 (a) along

with a structure comparison generated by overlaying the

structure of the palladium analog 8a (Figure 7, b). These

complexes are almost perfectly isostructural within differ-

ences in bond lengths of less than 2%. The interplane angle

Reactions of Cationic Allyl Complexes with Fluoride

In the first series of experiments, one of the complexes

between the allyl plane and the coordination plane (defined 8a, 8b, or 8c and one of the fluoride sources TBAT (4),

by P, Pt, N) in these structures is 64.8°, and the rotation of Me₄NF (5), or Schwesinger’s phosphazenium fluoride P₂F

the allyl vector normal plane [approximated by the plane (25)^[57]were mixed in deuterated solvents (CDCl₃or [D₃]-

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Cationic Palladium()- and Platinum()-η³-Allyl Complexes with Fluoride

FULL PAPER

Figure 7. X-ray crystal structures of the cationic 1,3-diphenylallyl complexes 18·PF₆, 8a, and 24. (a) ORTEP plot (30% probability

ellipsoids) of platinum complex 18·PF₆. The anion and most hydrogens are omitted for clarity. Selected data (bond lengths [Å]; bond

angles [°]): Pt–P = 2.265(2), Pt–N(2) = 2.121(5), Pt–C(27) = 2.283(6) =, Pt–C(28) = 2.195(6), Pt–C(29) = 2.113(6); N(2)–Pt–P = 94.5(2).

(b) Alignment of ball and stick representations of the complex cations of 8a (grey filled atoms, below) and 18·PF₆(white filled atoms,

on top). The structures of the complexes match closely. Selected data for 8a: Pd–P = 2.3123(8), Pd–N(2) = 2.159(3), Pd–C(27) = 2.283(3),

Pd–C(28) = 2.193(3), Pd–C(29) = 2.137(3); N(2)–Pd–P = 94.49(8). The atom numbering has been adapted here to match that from the

structure of 18·PF₆, but is different in the CSD CIF file. (c) ORTEP plot (30% probability ellipsoids) of platinum complex 24, anion and

hydrogen atoms are omitted for clarity. Selected data: Pt–C(1) = 2.233(8), Pt–C(2) = 2.168(7), Pt–C(3) = 2.233(8), Pt–P(1) = 2.258(2),

Pt–P(2) = 2.270(2); P(1)–Pt–P(2) = 86.37(8).

MeCN for 4, [D₃]MeCN for 5, C₆D₆for 25) and the sam- filtered solution gave 18·F as an amorphous yellow powder,

ples were then monitored using ¹H, ¹⁹F, and ³¹P NMR spec- which was soluble in most organic solvents. The ¹⁹F NMR

troscopy over a suitable range of time. If no change was spectrum of 18·F in CDCl₃consisted of a broad signal at δ

observed at room temperature the samples were warmed to = –139.8 ppm (∆_1/2= 15 Hz), a value which is close to that

50 °C. The appearance of peaks arising from allyl fluorides given by Grushin^[61](δ = –141 ppm, ∆_1/2= 9 Hz) for an

was carefully checked by ¹⁹F NMR spectroscopy (6: δ{¹⁹F} in situ generated naked fluoride in CDCl₃. In [D₈]toluene

= –165.4 ppm;^[14a]11: –175.2 ppm; indenyl fluoride: solution the ¹⁹F NMR peak for fluoride disappeared in

–201.24 ppm^[58]), but these signals were not detected. In ex- background noise that was generated from fluorinated poly-

periments with Me₄NF (5) and 1,3-diphenylallyl complex mers within the NMR probe head. The ³¹P NMR spectrum

–

8a, the main fluorinated species observed was DF₂, re-

sulting from deprotonation of [D₃]MeCN by naked fluo-

ride.^[31]A specific reaction pattern was only observed with

complex 8b and the naked fluorides Me₄NF (5, in [D₃]-

MeCN) and P₂F (25, in C₆D₆), where diene 26^[59]was re-

leased in an elimination reaction (Scheme 7). Other reactant

combinations resulted in no reaction at all or unspecific de-

composition with precipitation of palladium metal on heat-

ing.^[60]

Scheme 7. Fluoride-mediated elimination of diene 26 from dicyclo-

Figure 8. ³¹P NMR spectra of 18·PF₆, 18·Br, and 18·F.

(a) 101.3 MHz, [D₈]THF. 18·PF₆is exclusively present as the exo-

hexylallyl complex 8b.

syn-syn isomer. Note the ¹⁹⁵Pt satellites (J_Pt,P

= 5029 Hz).

We then turned our attention to the reaction of cationic

allylplatinum complex 18·PF₆with naked fluoride Me₄NF

(5). A suspension of the reactants in toluene was stirred at

ambient temperature, which resulted in a slow but clean

anion exchange reaction to give a yellow solution of 18·F

(b) 121.5 MHz, CDCl₃. 18·Br forms a mixture of four allyl isomers.

(c) 121.5 MHz, [D₈]toluene. 18·F forms a mixture of allyl isomers

whose lines are broadened due to exchange. (d) As in (c), but at

213 K (–60 °C). The interconversion of allyl isomers of 18·F is “fro-

zen” at low temperature, resulting in a spectrum similar to that of

and a colorless precipitate of Me₄NPF₆. Evaporation of the 18·Br at room temperature. Splitting due to J_P,Fis absent.

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L. Hintermann, F. Läng, P. Maire, A. Togni

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consists of one main broad peak and smaller additional sig- well-defined complex did not crystallize from solutions of

nals (Figure 8, c). On cooling to 213 K, the spectrum be- 27·F. The properties and spectroscopic data of 28·F match

comes clearer and a set of at least five lines (each with plati- closely those of the hydrated fluoride salts of cationic palla-

num satellites), corresponding to allyl isomers, appear (see dium complexes investigated earlier in our laboratory.^[8]The

d in Figure 8 and Table 2). Again, no peak was detected by analogous oxidative addition of 1,3-diphenylallyl bromide

¹⁹F NMR spectroscopy, but this should be seen in connec- (15) with Pd(dba)₂gave the η³-allyl bromide 27·Br

tion with experimental difficulties (mentioned above) and (Scheme 8).

1

the low concentration of the sample. The absence of ³¹P/

The H NMR spectroscopic data of 27·F and 27·Br in

¹⁹F couplings (which are so clearly visible for 21) shows DMSO are very similar to those of the known chloro ana-

that no inert covalent Pt–F bond is present in 18·F. When log 27·Cl.^[44b]

combined these pieces of evidence suggest that 18·F consists

of a mixture of isomeric allyl cations [Pt(2b)(η³-Ph₂All)]⁺

in solution, which form lipophilic contact ion pairs with

fluoride. The fluoride anions themselves are involved in a

fast exchange between the ion pairs. At room temperature

there is notable interconversion of configurationally iso-

meric allyl cations within 18·F (broad lines in the ³¹P NMR

spectrum, Figure 8, c), but slow interconversion among the

allyl isomers of 18·Br (separate, sharp lines in the ³¹P NMR

spectrum, Figure 8, b). This important finding directly re-

lates the nature of the counterion of a cationic allyl complex

to the kinetics of its allyl isomerization.

Discussion

Fluoride Effects in Asymmetric Allylation Reactions

We have identified two modes in the reaction of “naked”

or nucleophilic fluorides with cationic allyl complexes of

palladium() and platinum(): Allyl complexes bearing hy-

drogens α to the allyl group can either undergo base-medi-

ated elimination (see Scheme 7) or a simple anion exchange

can take place, which gives cationic allyl complexes as con-

tact ion pairs with fluoride as the counterion. NMR spec-

troscopic studies of the platinum complexes 18·PF₆, 18·Br,

and 18·F revealed that the counterion in these ion pairs

dramatically influences: (a) the allyl isomer composition at

equilibrium; and (b) the kinetics of exchange between these

isomers. In the presence of fluoride, allyl isomers intercon-

vert at room temperature (cf. Figure 8, c) whereas this pro-

cess is slow for the bromide salt (Figure 8, b) and probably

even slower for the hexafluorophosphate (Figure 8, a). This

evidence, obtained from a platinum model system, supports

our earlier proposal of an anion effect in the catalytic asym-

metric amination reaction (cf. Scheme 1):^[8]Addition of

fluoride accelerates the isomerization of allyl isomers and

therefore effectively deletes the “memory of chirality”^[63]

stored within the configuration of the allyl isomers. How-

ever, addition of PF₆^–has an inverse effect by slowing down

isomerization. This assumption has now been justified by

experimental results.

Oxidative Addition of Pd⁰with Ph₂AllF (6) and Ph₂AllBr

(15)

The failure to observe any allylic substitution products

resulting from attack of fluoride on cationic allyl complexes

indicates that this reaction is thermodynamically unfavor-

able.^[62]To test this assumption, we investigated whether the

reverse reaction, namely the oxidative addition of allyl fluo-

rides to Pd⁰, would proceed instead. The addition of a solu-

tion of 6^[14a]to either Pd(dba)₂or mixtures of Pd(dba)₂and

phosphanyl pyrazole (2c) (Scheme 8) did, in fact, result in

oxidative addition and the formation of η³-allylpalladi-

um() compounds 27·F or 28·F, respectively. Identification

of these compounds was based on the characteristic ¹H

NMR and ³¹P NMR spectra of the cationic units since a

The Viability of an (Asymmetric) Catalytic Allylic

Fluorination

The reaction of cationic allyl complexes of palladium()

and platinum() with naked or nucleophilic fluorides does

not produce allyl fluorides. On the contrary, the oxidative

addition of allyl fluoride 6 to Pd⁰proceeds with ease. This

finding is in agreement with calculations by Hagelin et al.

who have found that the attack of fluoride on the allylpalla-

dium() cation is energetically favorable in the gas phase,

but becomes unfavorable in the polar condensed phase be-

cause of the solvation of the fluoride anion.^[64]Despite this

thermodynamically unfavorable step, an overall catalytic al-

lylic fluorination reaction should still be exergonic, as long

as energetically high lying (reactive) sources of fluoride are

used. Nevertheless, the presence of an energetically low-ly-

ing, nonreactive intermediate (such as 18·F) in the reaction

Scheme 8. The oxidative addition of 1,3-diphenylallyl fluoride and

bromide to Pd⁰complexes is a spontaneous reaction that leads to

products containing the cationic allylpalladium() fragment. L = F

or solvent molecules.

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Cationic Palladium()- and Platinum()-η³-Allyl Complexes with Fluoride

FULL PAPER

H, HCMe), 6.67–6.75 (m, 2 H, aryl), 6.82 (d, J = 2.3 Hz, 5-H, Pz),

6.92–7.02 (m, 3 H, aryl), 7.28–7.33 (m, 3 H, aryl), 7.49–7.56 (m, 2

H, aryl) ppm. ³¹P NMR (101.3 MHz, CDCl₃): δ = –24.5 (s) ppm.

MS (EI): m/z (%) = 520 (100) [M⁺], 455 (25), 396 (20), 331 (59).

C₃₁H₃₃FeN₂P (520.44): calcd. C 71.54, H 6.39, N 5.38; found C

71.60, H 6.47, N 5.33.

pathway presents a severe obstacle for catalysis for kinetic

reasons. If possible, alternative pathways will be followed

(cf. release of 26 from 8b, Scheme 7) and Pd⁰will eventually

precipitate. These factors appear to cause the failure of the

desired palladium-catalyzed asymmetric allylic fluorination

reaction when it is carried out in analogy to known asym-

metric allylic substitutions.

Bis(µ-chloro)-bis(η³-1,3-dicyclohexylallyl)dipalladium(II

)

(7b):

A

suspension of Pd(dba)₂(658.7 mg, 1.146 mmol), 12 (403 mg,

1.266 mmol), and LiCl (1.203 mmol 1.05 equiv.) in THF (15 mL)

and MeCN (5 mL) was stirred for 15 min at 30 °C. The greenish

reaction mixture was evaporated to dryness, taken up in CH₂Cl₂

and filtered through SiO₂. Evaporation yielded 385.5 mg (97%) of

Conclusion

We have reported the synthesis of new cationic allyl com-

plexes of palladium() and platinum(), among them the

previously unknown (1,3-diphenylallyl)platinum() com-

plexes. The reactivity of these complexes towards naked and

nucleophilic sources of fluoride has been investigated. Stoi-

chiometric allylic fluorination was shown to be thermody-

namically unfeasible, and catalytic reactions are probably

also unfeasible due to a kinetic barrier in the reaction path-

way. It was shown that the counterions of cationic allylplati-

num() complexes determine both the exchange kinetics be-

tween allyl isomers and the isomer composition at equilib-

rium. This finding has been used to rationalize a “fluoride

anion effect” observed earlier in palladium-catalyzed asym-

metric allylic amination reactions.

1

a light yellow powder. M.p. 174 °C. H NMR (300 MHz, CDCl₃):

δ = 1.02–1.36 (m, 20 H-Cy), 1.53–1.87 (m, 20 H-Cy), 2.02–2.07 (m,

4 H-Cy), 3.62 (dd, J = 11.2 Hz, 5.2 Hz, 4 H, 1-H/1Ј-H, 3-H/3Ј-H),

5.14 (t, J = 11.2 Hz, 2 H, 2-H/2Ј-H) ppm. ¹³C NMR (CDCl₃): δ =

26.1 (CH₂), 26.2 (CH₂), 31.7 (CH₂), 32.8 (CH₂), 39.5 (CH), 88.2

(CH), 103.43 (CH) ppm. MS (FAB): m/z (%)

= 659 (100)

[M – Cl]⁺. C₃₀H₅₀Cl₂Pd₂(694.47): calcd. C 51.89, H 7.26; found C

51.77, H 7.09.

Indenylpalladium(II) Chloride (7c): In our hands, only the method

reported by Lin and Boudjouk gave a pure product.^[42]Others have

made similar observations.^[42b]We note that the use of 94% EtOH

in the synthesis is important because residual water favors the reac-

tion.

[Pd(η³-Ph₂All)(2b)]PF₆(8a): [Pd₂(µ-Cl)₂(η³-Ph₂All)₂] (226.8 mg,

0.338 mmol) was added to 2b (352.2 mg, 0.677 mmol) in acetone

(40 mL) and the mixture was stirred until dissolution occurred

(3 min). TlPF₆(236.4 mg, 0.677 mmol) was added and the resulting

suspension stirred for 1 h. Filtration through Celite, evaporation

to dryness, and precipitation from CH₂Cl₂/pentane gave 570.4 mg

(87%) of an orange powder. [α]_D= –278 (c = 0.50, CHCl₃). M.p.

Experimental Section

General Remarks: Syntheses of, and with, sensitive products were

performed using Schlenk and glovebox techniques. Naked fluorides

were handled exclusively in a glovebox. NMR spectroscopy: ¹H

NMR shifts relative to internal TMS, ¹³C NMR shifts relative to

TMS, but referenced by solvent signals, notably δ(CDCl₃) =

77.0 ppm. ¹⁹F NMR shifts relative to external CFCl₃, ³¹P NMR

shifts relative to external H₃PO₄(85%), ¹⁹⁵Pt NMR shifts relative

to external Na₂[PtCl₆] (aq). General techniques for NMR structure

elucidation were the same as in ref.^[29]For additional ¹³C NMR

and IR data, see ref.^[65]

1

dec. from 190 °C. H NMR (250 MHz, CDCl₃): δ = 0.48 (s, 9 H,

tBu), 2.35 (d, J = 6.9 Hz, 3 H, MeCH), 3.90 (s, 5 H, CpЈ), 3.97–

4.01 (m, 1 H-Cp), 4.41 (t, J = 2.6 Hz, 1 H-Cp), 4.54–4.58 (m, 1 H-

Cp), 5.25 (d, J = 10.0 Hz, allyl H, anti, trans N), 5.91 (d, J =

2.7 Hz, 4-H, Pz), 6.21 (dd, J = 14.1 Hz, 9.9 Hz, allyl H, central),

6.08–6.16 (m, 2 H, aryl), 7.01–7.32 (m, 15 H, 13 H, aryl + allyl H,

anti, trans P + CHMe), 7.45–7.55 (m, 3 H, aryl), 7.58 (d, J =

2.7 Hz, 5-H, Pz), 7.70–7.89 (m, 2 H, aryl) ppm. ¹³C NMR

(62.9 MHz, CDCl₃): δ = 18.4 (CH₃), 29.6 (CH₃), 31.8 (C), 58.4 (d,

J_P,C= 5 Hz, CH, CHMe), 66.0 (d, J_P,C= 3 Hz, CH, Cp), 66.1 (d,

J_P,C= 1 Hz, allyl CH, trans N), 70.6 (d, J_P,C= 6 Hz, Cp-CH), 71.3

(CH, CpЈ), 73.0 (CH, Cp), 74.9 [d, J_P,C= 42 Hz, C(1)-Cp], 93.8 [d,

J_P,C= 20, C(2)-Cp], 107.1 [CH, C(4) Pz], 107.1 (d, J_P,C= 19 Hz,

allyl CH, trans P), 112.4 (d, J_P,C= 4 Hz, allyl CH, central), 127.3

(d, J_P,C= 2 Hz, CH), 127.9 (d, J_P,C= 3, CH), 128.1 (d, J_P,C= 9 Hz,

CH), 128.3–129.4 (several CH), 130.7 (d, J_P,C= 48 Hz, C), 130.9

Abbreviations and Substances: All = allyl (C₃H₅), Ph₂All = 1,3-di-

phenylallyl etc., CC = column chromatography on SiO₂, HV = high

vacuum (Ͻ0.01 mbar), Ms = methylsulfonyl, Pz = pyrazole, tBu-

OMe = tert-butyl methyl ether. The following substances were pre-

pared according to literature procedures: (R,S_P)-PPFA^[27](recrys-

tallized twice from EtOH to ensure high enantiomeric purity), an-

hydrous Me₄NF (4),^[31]TBAT [tetrabutylammonium difluorotri-

phenylsilicate()] (5),^[30]3-tert-butylpyrazole,^[26][Pt₂(dba)₃],^[50]

[Pd₂(dba)₃]·CHCl₃or Pd(dba)₂,^[66][{PdCl(Ph₂All)}₂] (7a),^[44b]

[{PdCl(Ind)}_n] (7c),^[42]1,3-diphenylallyl bromide (15),^[47]Karstedt

catalyst (16).^[49b]Schwesinger’s phosphazenium fluoride P₂F (25)^[57]

was obtained from Fluka.

(d, J_P,C= 2 Hz, CH), 131.4 (d, J_P,C= 11 Hz, CH), 133.1 (d, J_P,C

=

44 Hz, C), 134.3 (d, J_P,C= 14 Hz, CH), 135.4 (d, J_P,C= 5 Hz, C),

138.9 (d, J_P,C= 3 Hz, C), 162.7 [C, C(3) Pz] ppm. ³¹P NMR

–

(101.3 MHz, CDCl₃): δ = –142 (sept, J_PF= 695 Hz, PF₆), 10.5

(s) ppm. IR (KBr): ν = 842 (s), 696 (m), 558 (m) cm^–1. MS (FAB):

˜

3-tert-Butyl-1-{(R)-1-[(S_P)-2-(diphenylphosphanyl)ferrocenyl]ethyl}-

1H-pyrazole (PPFPz{3-tBu}, 2b): Degassed HOAc (5 mL), (R,S)-

PPFA (2.047 g, 4.628 mmol) and 3-tert-butylpyrazole (862 mg,

6.94 mmol) were stirred for 1 d at 70 °C. After workup with water

and extraction with CH₂Cl₂, CC (tBuOMe/pentane, 1:20, and 3%

m/z (%) = 1783 (3) [2 M – PF₆]⁺, 819 (100) [M – PF₆]⁺, 625 (12)

[M – PF₆– Ph₂All]⁺. C₄₆H₄₆F₆FeN₂P₂Pd (965.07): calcd. C 57.25,

H 4.80, N 2.90; found C 57.08, H 4.95, N 2.94.

[Pd(η³-Cy₂All)(2b)]PF₆(8b): 7b (179.5 mg, 0.258 mmol) was added

NEt₃) gave 2.022 g (84%) as orange crystals. [α]_D= –281.7 (c = to a solution of 2b (269.1 mg, 0.517 mmol) in acetone (35 mL) and

0.88, MeOH). M.p. 130 °C. ¹H NMR (250 MHz, CDCl₃): δ = 1.06

(s, 9 H, tBu), 1.83 (d, J = 6.9 Hz, 3 H, MeCH), 3.87 (m, 1 H-Cp),

3.99 (s, 5 H, CpЈ), 4.34 (t, J = 2.5 Hz, 1 H-Cp), 4.64 (br. s, 1 H-

Cp), 5.52 (d, J = 2.3 Hz, 4-H, Pz), 5.77 (qd, J = 6.9 Hz, 3.2 Hz, 1

the mixture was stirred until dissolution was complete (15 min).

After addition of TlPF₆(180.6 mg, 0.517 mmol) and stirring for

1.5 h, the suspension was filtered through Celite and the filtrate

evaporated to dryness. Precipitation from CH₂Cl₂/pentane gave

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L. Hintermann, F. Läng, P. Maire, A. Togni

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484 mg (96%) of a yellow powder. M.p. 221° (dec.). ¹H NMR

(s, endo isomer) ppm. ¹²¹Sb NMR ([Ξ] = 71.8223640 MHz, [D₃]-

(250 MHz, CDCl₃). Major isomer: δ = 0.43–0.52 (m, 1 H-Cy), 0.82 MeCN): 93.1 (sept, J_Sb,F= 1936 Hz) ppm. MS (FAB): m/z (%) =

(s, 9 H, tBu), 0.76–1.85 (m, 21 H-Cy), 2.17 (d, J = 7.0 Hz, 3 H, 741.3 (100) [M Ind

–

SbF₆]⁺, 626.2 (33) [M SbF₆]⁺.

–

CHMe), 3.94–3.98 (m, 1 H-Cp), 3.96 (s, 5 H, CpЈ), 4.30 (dd, J =

10.4 Hz, 2.3 Hz, allyl H, anti, trans N), 4.46 (t, J = 2.6 Hz, 1 H-

Cp), 4.65–4.69 (m, 1 H-Cp), 5.27 (dd, J = 13.4 Hz, 10.0 Hz, allyl

H, central), 5.56 (dt, J = 13.3 Hz, 8.3 Hz, allyl H, trans P), 6.14 (d,

J = 2.6 Hz, 4-H, Pz), 6.51–6.62 (m, 2 H, aryl), 6.67 (q, J = 7.0 Hz,

CHMe), 7.14 –7.33 (m, 3 H, aryl), 7.58–7.66 (m, 3 H, aryl), 7.59

(d, J = 2.7 Hz, 5-H, Pz), 7.76–7.85 (m, 2 H, aryl); minor isomer):

δ = 0.76–1.80 (m, 22 H-Cy), 0.91 (s, 9 H, tBu), 2.04 (d, J = 7.0 Hz,

3 H, CHMe), 3.75–3.79 (m, 1 H-Cp), 3.90 (s, 5 H, CpЈ), 4.42 (t, J

= 2.6 Hz, 1 H-Cp), 4.58 (ddd, J = 13.7 Hz, 11.1 Hz, 5.5 Hz, allyl

H, anti, trans P), 4.76–4.80 (m, 1 H-Cp), 5.44 (t, J Ϸ 8.5 Hz, allyl

H, trans N) 5.94 (dd, J = 13.5 Hz, 7.8 Hz, allyl H, central), 6.21 (d,

J = 2.7 Hz, 4-H, Pz), 6.34 (q, J = 7.0 Hz, CHMe), 6.45–6.60 (m, 2

H, aryl), 7.14–7.33 (m, 3 H, aryl), 7.58–7.66 (m, 3 H, aryl), 7.68

(d, J = 2.7 Hz, 5-H, Pz), 7.76–7.85 (m, 2 H, aryl) ppm. ³¹P NMR

C₄₀H₄₀F₆N₂PFePdSb (977.74): calcd. C 49.14, H 4.12, N 2.87;

found C 48.84, H 4.17, N 2.80.

(E)-1,3-Dicyclohexylprop-2-en-1-ol (10): (a) (E)-1,3-Dicyclohex-

ylpropenone: Acetylcyclohexane (9) (6.9 mL, 50 mmol) was slowly

dropped into a stirred solution of LDA (31 mL, 2  in hexanes,

62 mmol) in THF (80 mL) at –78 °C. After 1 h, CyCHO (6.9 mL,

57.1 mmol) was slowly added and the reaction mixture stirred for

4 h at –78 °C. MsCl (9.7 mL, 125 mmol) was added dropwise. After

1 h the reaction mixture was warmed to room temp., quenched with

sat. NaHCO₃solution (50 mL) and extracted with tBuOMe. The

organic phases were dried (Na₂SO₄) and the solvents evaporated.

DBU (12.4 mL, 83.3 mmol) was added dropwise at 0 °C to the resi-

due in acetone (100 mL). After 1 h stirring, workup (NH₄Cl sat/

tBuOMe) gave an oil which was purified by CC (tBuOMe/hexanes,

1:20) to give 7.707 g (70%) of a colorless liquid. ¹H NMR

(300 MHz, CDCl₃): δ = 1.08–1.82 (m, 20 H-Cy), 2.08–2.19 (m, 1

H-Cy), 2.50–2.60 (m, 1 H-Cy), 6.10 (dd, J = 15.9 Hz, 1.4 Hz, 2-H),

6.80 (dd, J = 15.9 Hz, 6.8 Hz, 3-H) ppm. ¹³C NMR (62.9 MHz,

CDCl₃): δ = 25.7 (CH₂), 25.7 (CH₂), 25.9 (CH₂), 25.9 (CH₂), 28.7

(CH₂), 31.8 (CH₂), 40.6 (CH), 48.6 (CH), 126.0 [CH, C(3)], 151.9

[CH, C(2)], 203.9 [C(1)] ppm. MS (CI): m/z (%) = 221 (100) [M +

H]⁺, 165 (3), 137 (61) [C₉H₁₃O]⁺, 83 (11), [C₆H₁₁]⁺, 55 (15). IR

–

(101.3 MHz, CDCl₃): δ = –144.3 Hz (sept, J_P,F= 698, PF₆), 10.9

(s, major isomer), 11.9 (s, minor isomer) ppm. MS (FAB): m/z (%)

= 1809.5 (2) [2 M – PF₆]⁺, 831.4 (100) [M – PF₆]⁺, 710 (6) [M –

PF₆– Cy₂All]⁺, 627 (74). C₄₆H₅₈F₆FeN₂P₂Pd (977.18): calcd. C

56.54, H 5.98, N 2.87; found C 56.48, H 5.91, N 2.82.

[Pd(η³-Ind)(2b)]SbF₆(8c): A mixture of 2b (320 mg, 0.62 mmol)

and 7c (155 mg, 0.30 mmol) was stirred in THF (5 mL) until dissol-

ution was complete (20 min). AgSbF₆(206 mg, 0.60 mmol) was

added to the dark red solution, and the resulting suspension was

stirred for 1 h. After filtration through Celite and evaporation, the

residue was precipitated from CH₂Cl₂/tBuOMe to give a dark red

powder, which was redissolved in CH₂Cl₂and set aside for slow

diffusion against hexane at –20 °C. Within 2 d dark red crystals

(also used for X-ray) of a CH₂Cl₂solvate were formed. The yield

of solvent-free compound after drying is 483 mg (82%). It is stable

as a solid, but slow decomposition occurs in solution and in air.

¹H NMR (400 MHz, [D₃]MeCN, exo isomer): δ = 0.80 (s, 9 H,

tBu), 1.74 (d, J = 7.1 Hz, 3 H, CHMe), 3.85 (s, 5 H, CpЈ), 4.08–

4.10 (m, 5-H, Cp), 4.54 (t, J = 2.7 Hz, 4-H, Cp), 4.74–4.77 (m, 3-

H, Cp), 5.52 (qd, J = 7.1 Hz, 1.2 Hz, 1 H, CHMe), 6.28 (d, J =

2.7 Hz, 4-H, Pz), 6.44–6.50 (m, 2 H_ortho,axial), 6.60 (t, J = 2.5 Hz,

3-H, Ind), 6.76 (dddd, J = 9.2 Hz, 3.5 Hz, 2.0 Hz, 0.8 Hz, 1-H,

Ind), 6.82 (ddd, J = 3.5 Hz, 3.0 Hz, 0.6 Hz, 2-H, Ind), 7.14–7.19

(m, 2 H_meta,axial), 7.26, (obscured, 6-H, Ind), 7.28 (obscured, 7-H,

Ind), 7.30 (obscured, 1 H_para,axial), 7.35, (obscured, 5-H, Ind), 7.68–

7.75 (m, 2 H_meta,equ+ 1 H_para,equ), 7.70, (obscured, 4-H, Ind), 7.71

[d, J = 2.7 Hz, 5-H, Pz (obscured)]. 7.88–7.96 (m, 2 H_ortho,equ) ppm;

(CHCl ): ν = 1684 (m, C=O), 1655 (m), 1620 (m, C=C) cm^–1.

˜

3

C₁₅H₂₄O (220.35): calcd. C 81.76, H 10.98; found C 82.02, H 11.03.

(b) (E)-1,3-Dicyclohexyl-2-propen-1-ol (10): NaBH₄(167 mg,

4.41 mmol) was added to a solution of 1,3-dicyclohexylpropenone

(973 mg, 4.41 mmol) and CeCl₃·7H₂O (1646 mg, 4.41 mmol) in

MeOH (12 mL) at room temp. The mixture was stirred for 10 min

and worked up with aq. HCl (2.5 , 3 mL), H₂O and tBuOMe.

Purification by CC (tBuOMe/hexanes, 1:10) gave 758 mg (77%) of

1

a colorless liquid. H NMR (CDCl₃): δ = 0.85–1.42 (m, 11 H-Cy),

1.45 (d, J = 3.0 Hz, OH), 1.63–1.74 (m, 9 H-Cy), 2.01–1.81 (m, 2

H-Cy), 3.75 (ddd, J = 6.9 Hz, 6.9 Hz, 3.1 Hz, 3-H), 5.39 (ddd, J =

15.5 Hz, 7.2 Hz, 0.9 Hz, 2-H), 5.56 (dd, J = 15.5 Hz, 6.5 Hz, 1-H)

ppm. Known compound, CAS number 79605-63-3.

(E)-1,3-Dicyclohexylallyl Fluoride (11): DAST (101.8 mg,

0.63 mmol) was added at –78 °C to a solution of 10 (126.6 mg,

0.569 mmol) in CH₂Cl₂(11 mL) while stirring. The temperature

was raised to 0 °C and the mixture stirred for another 10 min.

Quenching with aq. NaHCO₃(10 mL), followed by extraction with

three portions of tBuOMe (20 mL) gave, after drying (MgSO₄) and

evaporation, 130 mg (quant.) of a yellowish oil. Kugelrohr distil-

1

assignments from HH COSY and long-range H,¹³C HMQC. H

NMR (300 MHz, CDCl₃, minor isomer, selected peaks): δ = 0.49

(s, 9 H, tBu), 2.13 (d, J = 7.0 Hz, 3 H, MeCH), 4.00 (m, 1 H-Cp),

4.04 (s, 5 H, CpЈ), 5.84 (t, J = 2.4 Hz, 1 H-Cp), 6.09 (d, J = 2.8 Hz,

1 H-Pz), 6.97 (m, CHMe), 7.59 (d, J = 2.8 Hz, 1 H-Pz) ppm. Iso-

mer ratio in CDCl₃exo/endo = 11:1, in [D₃]MeCN = 16:1. ¹H{³¹P}

NMR (250 MHz, [D₃]MeCN, ³¹P-decoupling at δ = 12.2 ppm, se-

lected peaks): δ = 4.08 (dd, J = 2.7 Hz, 1.3 Hz, 5-H, Cp), 4.54 (dt,

J = 2.7 Hz, 0.6 Hz, 4-H, Cp), 4.75 (ddd, J = 2.7 Hz, 1.3 Hz, 0.5 Hz,

3-H, Cp), 6.27 (dd, J = 2.8 Hz, 0.6 Hz, 5-H, Pz), 6.44–6.49 (m, 2

H, H, aryl ortho), 6.60 (ddd, J = 3.1 Hz, 2.0 Hz, 0.5 Hz, 3-H, Ind),

6.75 (ddd, J = 3.5 Hz, 2.0 Hz, 0.8 Hz, 1-H, Ind), 6.82 (dd, J =

1

lation (90 °C/0.01 mbar) gave a colorless oil. H NMR (250 MHz,

CDCl₃): δ = 0.9–2.1 (m, 22 H-Cy), 4.49 (dt, J = 48.6 Hz, 7.2 Hz,

1-H), 5.44 (dddd, J = 15.6 Hz, 9.8 Hz, 7.6 Hz, 1.3 Hz, 2-H), 5.67

(ddd,

J =

15.6 Hz, 6.4 Hz, 4.6 Hz, 3-H) ppm. ¹³C NMR

(62.9 MHz, CDCl₃): δ = 25.7 (CH₂), 25.9 (CH₂), 25.9 (CH₂), 26.1

(CH₂), 26.4 (CH₂), 28.1 (d, J_F,C= 5, CH₂), 28.2 (d, J_F,C= 5 Hz,

CH₂), 32.5 (d, J_F,C= 2 Hz, CH₂), 32.7 (d, J_F,C= 2 Hz, CH₂), 40.3

(CH), 42.5 (d, J_F,C= 22 Hz, CH), 98.5 [d, J_F,C= 164 Hz, CH, C(1)],

124.5 [d, J_F,C= 20 Hz, CH, C(2)], 141.8 [d, J_F,C= 12 Hz, CH,

C(3)] ppm. ¹⁹F NMR (282.4 MHz, CDCl₃): δ = –175.2 (dddt, J_F,H

Ϸ 48.5 Hz, 13.9 Hz, 9.8 Hz, 5 Hz) ppm.

3.5 Hz, 3.1 Hz, 2-H, Ind) ppm. ¹³C NMR (100 MHz, [D₃]MeCN): (E)-1,3-Dicyclohexylallyl Trifluoroacetate (12): TFAA (0.634 mL,

selected signals, δ = 77.3 [d, J_P,C= 4 Hz, C(3) Ind], 99.0 (d, J_P,C

=

4.56 mmol) was slowly added to 10 (506.8 mg, 2.28 mmol) in pyri-

dine (8.6 mL) at 0 °C and the reaction mixture stirred for 1 h.

21 Hz, C(1) Ind), 115.9 [d, J_P,C= 6 Hz, C(2) Ind] ppm, C(1) defined

as trans to P. ¹⁹F NMR (282.4 MHz, [D₃]MeCN): δ = –124.3 (6 Workup with tBuOMe and washing of the organic phase (aq. HCl,

lines, J_121Sb,19F= 1935 Hz, and 8 lines, J_123Sb,19F= 1060 Hz) ppm.

aq. sat. NaHCO₃, H₂O) gave, after drying (Na₂SO₄) and evapora-

³¹P NMR (121.5 MHz, [D₃]MeCN): δ = 12.2 (s, exo isomer), 12.4 tion, 680 mg (93%) of a colorless liquid. An analytical sample was

1406

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Eur. J. Inorg. Chem. 2006, 1397–1412

Cationic Palladium()- and Platinum()-η³-Allyl Complexes with Fluoride

FULL PAPER

purified by Kugelrohr distillation (90 °C/0.005 mbar). The sub-

= 56, allyl H, central), 6.05 (d, J = 2.9 Hz, J_Pt,HϷ 11 Hz, 4-H, Pz),

6.35–6.43 (m, 2 H, aryl), 6.89 (dd, J = 13.8 Hz, 7.0 Hz, J_Pt,H

stance decomposed within a few days at room temp. ¹H NMR

=

(250 MHz, CDCl₃): δ = 0.92–1.31 (m, 10 H-Cy). 1.60–1.77 (m, 10 49 Hz, allyl H, anti, trans P), 7.04–7.08 (m, 3 H, aryl), 7.10–7.18 (5

H-Cy), 1.92–2.04 (m, 2 H-Cy), 5.10 (dd, J = 8.1 Hz, 7.2 Hz, 1-H), H, aryl), 7.22–7.32 (m, 3 H, aryl), 7.25 (q, J = 6.9 Hz, CHMe),

5.34 (ddd, J = 15.5 Hz, 8.4 Hz, 1.3 Hz, 2-H), 7.75 (dd, J = 15.5 Hz, 7.34–7.39 (m, 2 H, aryl), 7.42–7.50 (m, 3 H, aryl), 7.75–7.82 (m, 2

6.6 Hz, 3-H) ppm. ¹³C NMR (62.9 MHz, CDCl₃): δ = 25.6 (CH₂),

25.7 (CH₂), 25.8 (CH₂), 26.0 (CH₂), 26.2 (CH₂), 28.4 (CH₂), 32.4

H, aryl), 7.98 (d, J = 2.9 Hz, 5-H, Pz) ppm. ¹³C NMR (62.9 MHz,

[D₈]THF): δ = 18.2 (CH₃), 30.8 (s, J_Pt,C= 7 Hz, CH₃), 33.1 (C),

(CH₂), 40.3 (CH), 41.3 (CH), 84.7 (CH), 122.1 (CH), 143.8 51.4 (s, J_Pt,C= 318 Hz, allyl CH, trans N), 59.5 (d, J_P,C= 3 Hz,

(CH) ppm. IR (CHCl ): ν = 1777 (s), 1450 (s), 1272 (s) cm^–1. CHMe), 67.9 [d, J_P,C= 7 Hz, CH, C(3) Cp], 71.9 [d, J_P,C= 7 Hz,

˜

3

C₁₇H₂₅F₃O₂(318.38): calcd. C 64.13, H 7.91; found C 63.94, H

8.07.

CH, C(4) Cp], 72.3 (CH, CpЈ), 74.4 [d, J_P,C= 3 Hz, J_Pt,C= 40 Hz,

CH, C(5Ј) Cp], 75.4 (d, J_P,C= 58 Hz, C), 94.8 (d, J_P,C= 17 Hz, C),

100.7 (d, J_P,C= 19 Hz, CH, All trans P), 108.9 [s, J_Pt,C= 34 Hz,

CH, C(4) Pz], 109.8 (s, J_Pt,C= 33 Hz, allyl CH, central), 127.2

Bis(µ-trifluoroacetato)-bis(η³-1,3-dicyclohexylallyl)dipalladium(II

)

(13): A suspension of Pd(dba)₂(756 mg, 1.32 mmol) and 12

(461 mg, 1.45 mmol) in THF (12 mL) and MeCN (3 mL) was

stirred for 1 h at room temp. , followed by 10 min at 40 °C. The

resulting solution was evaporated to dryness and repeatedly ex-

tracted with MeCN/H₂O (70:30). The extract was evaporated to a

yellow powder, which was purified by precipitation from Et₂O/pen-

tane to give 520 mg (93%) of yellow crystals. M.p. 82 °C (dec.). ¹H

NMR (250 MHz, C₆D₆+ 10% [D₃]MeCN): δ = 1.00–1.98 (m, 44

H-Cy), 3.43 (dd, J = 11.6 Hz, 4.9 Hz, 4 H, 1-H, 1Ј-H, 3-H, 3Ј-H),

5.10 (t, J = 11.6 Hz, 2 H, 2-H, 2Ј-H) ppm. VT NMR: see Scheme 5

and Table 1. ¹³C NMR (75.5 MHz, CDCl₃/[D₃]MeCN 3:1): δ =

25.5 (CH₂), 25.6 (CH₂), 25.6 (CH₂), 31.6 (CH₂), 32.0 (CH₂), 39.1

(CH), 88.2 (br., CH), 106.5 (br., CH) ppm. MS (FAB): m/z (%)

= 1084 (9), 737 (47) [M – OCOCF₃]⁺, 311 (100) [Pd(Cy₂All)]⁺.

C₃₄H₅₀F₆O₄Pd (849.60): calcd. C 48.99, H 6.05; found C 48.09, H

5.92.

(CH), 128.8 (CH), 129.1 (d, J_P,C= 10 Hz, CH) 129.1 (d, J_P,C

=

2 Hz, CH), 129.3 (CH), 129.4 (d, J_P,C= 1 Hz, CH), 129.5 (d, J_P,C

= 1 Hz, CH), 129.6 (d, J_P,C= 1 Hz, CH), 130.9 (CH), 130.9 [CH,

C(5) Pz], 131.1 (d, J_P,C= 65 Hz, C), 131.8 (d, J_P,C= 3 Hz, CH),

132.9 (d, J_P,C= 10 Hz, CH, ortho-PPh axial), 134.2 (d, J_P,C= 57 Hz,

C), 135.4 (d, J_P,C= 13 Hz, CH, ortho-PPh equatorial), 136.8 (d,

J_P,C= 4 Hz, C), 142.0 (d, J_P,C= 1 Hz, C), 163.2 [C, C(3) Pz] ppm.

³¹P NMR (161.9 MHz, [D₈]THF): δ = –142.7 (sept, J_PF= 714 Hz,

PF₆), 10.4 (s, J_Pt,P= 5029 Hz), 9.2 (s, minor isomer, Ͻ2%). ¹⁹⁵Pt

–

NMR (86.0 MHz, HMQC, [D₈]THF): δ = –4453 (d, J_Pt,P

5030 Hz) ppm. C₄₆H₄₆F₆FeN₂P₂Pt (1053.75): calcd. C 52.43, H

4.40, N 2.66; found C 52.38, H 4.44, N 2.63.

=

[Pt(η³-Ph₂All)(2b)]Br (18·Br):

A combination of 2b (30 mg,

58 mmol) and 17 (27 mg, 29 mmol) in THF (2 mL), followed by

filtration and evaporation gave a yellow residue. Crystallization

from CH₂Cl₂/pentane at 5 °C (over layering) produced fine yellow

needles (43.5 mg, 76%). Additional material was crystallized from

the mother liquors (12 mg, total 97%). M.p. 141–147 °C. ³¹P NMR

(101.3 MHz, CDCl₃) and ¹⁹⁵Pt NMR (HMQC, 64.3 MHz, CDCl₃):

see Table 2. MS (FAB): m/z (%) = 908.4 (73) [M – Br]⁺, 715.3 (100)

[M – Br – Ph₂All]⁺. C₄₆H₄₆BrFeN₂PPt (988.69): calcd. C 55.88, H

4.69, N 2.83; found C 55.99, H 4.74, N 2.75.

Di-µ-bromo-bis(η³-1,3-diphenylallyl)diplatinum(II) (17): (a) A Kar-

stedt complex solution (corresponding to 4 mmol of Pt) was added

dropwise to a solution of 15 (1.37 g, 5.0 mmol) in tBuOMe (30 mL)

at 0 °C while stirring. A vanilla-yellow powder precipitated. After

stirring for 2 h at 0 °C, filtration and washing with MeOH, a fine,

bright yellow powder (1.440 g, 77%) was obtained that was hardly

soluble in any solvents, except for DMSO and pyridine. (b) A sus-

pension of Pt₂(dba)₃(109 mg, 0.1 mmol) and 15 (58 mg,

0.21 mmol) in acetone (2 mL) and THF (2 mL) was stirred for 1 d

at room temp. The reaction mixture was evaporated to dryness and

the solid was suspended in MeOH (2 mL) and filtered. Washing

with MeOH and acetone gave 66 mg (70%) of a greyish yellow

powder. The discoloration was caused by finely divided Pt⁰already

present in Pt₂(dba)₃. M.p. 159 °C (dec.). ¹H NMR (250 MHz, [D₆]-

DMSO): δ = 4.46 (d, J = 11.0 Hz, J_Pt,HϷ 56 Hz, 4 H, 1-H, 3-H),

6.05 (t, J = 11.0 Hz, J_Pt,HϷ 76 Hz, 2 H, 2-H), 7.10–7.70 (m, 20 H,

aryl) ppm. ¹³C NMR (62.9 MHz, [D₆]DMSO): δ = 74.6 (br.), 104.7,

[Pt(η³-Ph₂All)(2b)]F (18·F): (a) Me₄NF (17 mg, 0.18 mmol) was

added to a solution of 18·PF₆(128 mg, 0.12 mmol) in THF (1 mL)

and the resulting suspension stirred at room temp. Samples of the

supernatant solution were taken and C₆D₆was added for locking

–

purposes, and the NMR spectra recorded. After 1 d, some PF₆

remained in the solution (¹⁹F NMR, ³¹P NMR), but after 2 d such

signals had disappeared. The reaction mixture was filtered and the

filtrate evaporated under HV. A yellow solid remained which was

soluble in benzene. ¹⁹F NMR (282.4 MHz, CDCl₃): δ = –139.8 (br.

s, ∆_1/2= 15 Hz, F^–) ppm. ³¹P NMR (121.5 MHz, CDCl₃): δ = 2.2

(s, J_Pt,P= 3903 Hz), 3.5 (s, J_Pt,P= 4094 Hz), 7.0 (br. s, J_Pt,P

3947 Hz) ppm.

=

130.7, 131.3, 131.8, 141.4 ppm. IR (KBr): ν = 755 (s), 698 (s) cm^–1.

˜

C₃₀H₂₆Br₂Pt₂(936.50): calcd. C 38.48, H 2.80; found C 38.54, H

2.89.

(b) Reaction in toluene: 18·PF₆(115 mg) and Me₄NF (15 mg) were

stirred for 2 d in [D₈]toluene (3 mL). The sample was filtered into

a J. Young NMR tube. ¹⁹F NMR (282 MHz, [D₈]toluene, 298 K):

δ = –116 (br. s) ppm. Note that the signal is within a region of

heavy artifacts (due to fluoropolymers within the NMR probe

head). ³¹P NMR (121.5 MHz, [D₈]toluene, 298 K): δ = 2.4 (s, J_Pt,P

[Pt(η³-Ph₂All)(2b)]PF₆(18·PF₆): Ligand 2b (515 mg, 0.99 mmol)

and 17 (463 mg, 0.494 mmol) were stirred in acetone (10 mL) until

they had completely dissolved. Epichlorohydrine (1.0 mL,

12.8 mmol) and HPF₆(1 , 1.1 mL, 1.1 mmol, freshly prepared

from 75% aq. HPF₆and EtOH) were added, and the mixture

stirred for 20 min and then evaporated to dryness. The residue was

thoroughly dried under HV, washed with tBuOMe and then dis-

solved in CH₂Cl₂(5 mL) and the solution filtered through a cotton

plug into MeOH (10 mL). On standing in the fridge (4 °C), dark

= 3908 Hz), 4.1 (br. s, J_Pt,P= 4070 Hz), 7.8 (br. s, J_Pt,P

=

3938 Hz) ppm. VT ³¹P NMR (121.5 MHz, [D₈]toluene, 213 K): see

Table 2.

[PtCl₂(2b)] (19): Bis(styrene)platinum() chloride (0.475 g,

1.00 mmol) and 2b (0.5377 g, 1.03 mmol) were stirred in CH₂Cl₂

1

orange crystals formed (763 mg, 73%). H NMR (400 MHz, [D₈]-

THF): δ = 0.51 (s, 9 H, tBu), 2.37 (d, J = 6.9 Hz, 3 H, MeCH), (10 mL) for 1 d at 40 °C. Filtration through Celite, evaporation to

3.94 (s, 5 H, CpЈ), 4.05–4.08 (m, 1 H-Cp), 4.51 (t, J = 2.3 Hz, 1 H- 2 mL and addition of pentane gave an orange precipitate. This was

Cp), 4.79–4.80 (m, 1 Cp-H), 4.81 (d, J = 9.2 Hz, J_Pt,H= 77 Hz, dissolved in a little CH₂Cl₂and over layered with EtOAc. Slow

allyl H, anti, trans N), 5.86 (ddd, J = 13.9 Hz, 9.1 Hz, 2.1 Hz, J_Pt,Hevaporation in the fume hood gave orange-red crystals containing

Eur. J. Inorg. Chem. 2006, 1397–1412

www.eurjic.org

1407

L. Hintermann, F. Läng, P. Maire, A. Togni

FULL PAPER

the solvent of crystallization. Yield as [PtCl₂(2b)]·0.35

CH₂Cl₂·0.25AcOEt: 0.716 g (87%). An analytical sample was dried

to remove solvents of crystallization. M.p. 215 °C (dec.). H NMR

[M – Ph]⁺, 715.3 (100) [M – 2 Ph]⁺. C₄₃H₄₃FeN₂PPt (869.73): calcd.

C 59.38, H 4.98, N 3.22; found C 59.38, H 5.05, N 3.21.

1

[Pt(Ph)F(2b)] (21): In an NMR tube, 20 (10 mg) in CDCl₃(0.5 mL)

was mixed with 2 drops of NEt₃·(HF)₃. NMR analysis revealed

(300 MHz, CDCl₃): δ = 1.18 (s, 9 H, tBu), 2.12 (d, J = 7.2 Hz, 3

H, CHMe), 3.75–3.79 (m, 1 H-Cp), 4.16 (s, 5 H, CpЈ), 4.41 (t, J =

2.5 Hz, 1 H-Cp), 4.74–4.79 (m, 1 H-Cp), 6.05 (d, J = 2.9 Hz, 4-H,

Pz), 6.68–6.78 (m, 2 H, aryl), 7.14–7.23 (dt, J = 8 Hz, 3 Hz, 2 H,

aryl), 7.29–7.36 (m, 1 H, aryl), 7.42–7.58 (m, 3 H, aryl), 7.52 (d, J

= 2.9 Hz, 5-H, Pz), 8.08 (q, J = 7.2 Hz, CHMe), 8.11–8.20 (m, 2

H, aryl) ppm. ¹³C NMR (62.9 MHz, CDCl₃): δ = 17.3 (CH₃,

CHMe), 31.3 (CH₃, tBu), 33.3 (C, tBu), 57.5 (CH, CHMe), 68.0

(d, J_P,C= 8 Hz, CH, Cp), 70.7 (d, J_P,C= 7 Hz, CH, Cp), 71.1 [d,

J_P,C= 67 Hz, C, C(1)-Cp], 71.3 (CH, CpЈ), 73.8 (d, J_P,C= 4 Hz,

CH, Cp), 92.4 [d, J_P,C= 15 Hz, C, C(2)-Cp], 107.8 [CH, C(4)-Pz],

127.4 (d, J_P,C= 11 Hz, CH), 127.5 (d, J_P,C= 68 Hz, C), 127.6 [CH,

C(5)-Pz], 128.3 (d, J_P,C= 10 Hz, CH), 130.1 (d, J_P,C= 3 Hz, CH),

131.3 (d, J_P,C= 3 Hz, CH), 131.6 (d, J_P,C= 10 Hz, CH), 132.7 (d,

J_P,C= 61 Hz, C), 135.7 (d, J_P,C= 10 Hz, CH), 162.7 [C, C(3)-

1

two species (ratio 1.4:1) with similar H NMR spectra. The major

species was the fluoro complex and the minor species remains un-

known. No attempt was made to isolate the compounds. ¹H NMR

(300 MHz, CDCl₃), selected signal: δ = 7.36 (s, 6 H, benzene) ppm.

¹⁹F NMR (282.4 MHz, CDCl₃): δ = –214.6 (d, J_P,F= 207 Hz, J_Pt,F

= 210 Hz), –129.7 (br. s, Et₃NH⁺/F^–, excess reagent), –165.0 (br. s,

HF/HF₂) ppm. ³¹P NMR (121.5 MHz, CDCl₃): δ = –9.6 (s, J_Pt,P

–

= 5107 Hz), –11.8 (d, J_PF= 207, J_Pt,P= 5104 Hz) ppm.

[Pt(η³-All)(2b)]SbF₆(22): [{PtCl(C₃H₅)}₄]^[67](103 mg, 0.095 mmol)

and 2b (203 mg, 0.39 mmol) were stirred in acetone (3 mL) and

CH₂Cl₂(3 mL) until a homogeneous solution was obtained.

AgSbF₆(135 mg, 0.39 mmol) was added and the resulting suspen-

sion stirred for 30 min. After filtration through Celite and evapora-

tion, the residue was purified by precipitation from acetone/hexane

to give 284 mg (71%) of orange crystals containing 0.5 equiv. ace-

tone. ³¹P NMR (81.0 MHz, CDCl₃): δ = 12.5 (s, J_Pt,P= 4413 Hz,

exo isomer), 12.6 (s, endo isomer) ppm. MS (FAB): m/z (%) =

1276.8 (16) [2 M – PF₆]⁺, 756.4 (100) [M – PF₆]⁺, 715.4 (25), [M –

PF₆– C₃H₅]⁺. C₃₄H₃₈F₆FeN₂PPtSb·0.5C₃H₆O (1021.36): calcd. C

41.75, H 4.05, N 2.74; found C 41.83, H 4.00, N 2.83.

Pz] ppm. ³¹P NMR (125.5 MHz, CDCl₃): δ = –16.1 (s, J_Pt,P

=

3783 Hz) ppm. ¹⁹⁵Pt NMR (HMQC, 64.525 MHz, CDCl₃): δ = –

3700 (d, J_Pt,P= 3790 Hz) ppm. MS (FAB): m/z (%) = 1537 (50) [2

M – Cl]⁺, 786 (27) M⁺, 750 (92) [M – Cl]⁺, 714 (100) [M – 2 Cl]⁺,

630 (74). C₃₁H₃₃Cl₂FeN₂PPt (786.42): calcd. C 47.35, H 4.23, N

3.56; found C 47.43, H 4.45, N 3.61.

[PtPh₂(2b)] (20): (a) Complex 19 (100 mg, 0.127 mmol) was added

to a 10–20 fold excess of PhMgBr in THF (ca. 2 mL) and stirred

for 1 d at 50 °C. Quenching with aq. NH₄Cl and extraction with

tBuOMe, followed by drying of the organic phase (MgSO₄) and

evaporation gave a yellow semisolid. This was crystallized from

heptane/CH₂Cl₂by slow evaporation at 4 °C to give orange-yellow

crystals (81 mg, 73%).

[Pt(η³-2-MeAll)(2b)]PF₆(23): Ligand 2b (193 mg, 0.37 mmol) and

[Pt₂(µ-Cl)₂(2-MeAll)₂]^[68](98.6 mg, 0.17 mmol) were stirred at room

temp. for 2 h in CH₂Cl₂(3 mL). AgPF₆(94 mg, 0.37 mmol) in

MeOH (3 mL) was added and the resulting suspension was stirred

for 30 min, then filtered through Celite. The solution was evapo-

rated to dryness and the residue crystallized from CH₂Cl₂/tBuOMe

(slow diffusion) to give 254 mg (81%) of orange crystals. ³¹P NMR

–

(81.0 MHz, CDCl₃): δ = –143.5 (sept, J_PF= 713 Hz, PF₆), 11.5 (s,

(b) An aged solution of PhMgBr (2 mL, 2 , 4 mmol) was added

dropwise to 19 (0.21 mmol) in THF (7 mL). After stirring for 1 d

at 50 °C the reaction was quenched with water and extracted with

tBuOMe. Drying over MgSO₄and evaporation gave an orange oil

that was filtered through SiO₂using tBuOMe/hexane (1:10). The

yellow fractions were collected and the solvents evaporated. Hep-

tane (3 mL) was added to the residue and enough CH₂Cl₂to dis-

solve all solids. Diffusion against heptane at –20 °C gave 160 mg

(79%) of orange crystals of the phenol adduct (20·PhOH, M_r=

963.82). The PhOH was apparently an impurity arising from the

Grignard reagent used. Analytical data for the solvate-free com-

J_Pt,P= 4291 Hz, major isomer); 11.9 (s, J_Pt,P= 4010 Hz, minor

isomer) ppm. MS (FAB): m/z (%) = 770.4 (100) [M – PF₆]⁺.

C₃₅H₄₀F₆FeN₂P₂Pt (915.57): calcd. C 45.91, H 4.40, N 3.06; found

C 45.97, H 4.61, N 3.03.

[Pt(η³-Ph₂All)(dppe)]PF₆(24):

A

mixture of 17 (51.5 mg,

0.055 mmol) and 1,2-bis(diphenylphosphanyl)ethane (43.8 mg,

0.11 mmol) in acetone (1 mL) and CH₂Cl₂(1 mL) was stirred until

completely dissolved. Epichlorohydrine (0.1 mL, 1.28 mmol) and

HPF₆solution [0.1 mL, 0.114 mmol; freshly prepared from 0.6 mL

HPF₆(75%) and EtOH up to 5.0 mL total volume] were then

added dropwise. After 30 min stirring, the reaction mixture was

1

pound: M.p. 185–189 °C (dec.). H NMR (250 MHz, CDCl₃): δ =

0.66 (s, 9 H, tBu), 2.21 (d, J = 7.3 Hz, 3 H, MeCH), 3.66–3.71 (m, evaporated to dryness and the residue dried under HV. The yellow

1 H-Cp), 3.97 (s, 5 H, CpЈ), 4.30 (t, J = 2.6 Hz, 1 H-Cp), 4.66–4.71 solid was dissolved in CH₂Cl₂(2 mL), the solution filtered through

(m, 1 H-Cp), 5.95 (d, J = 2.7 Hz, 4-H,Pz), 6.49–6.59 (m, 2 H, aryl),

6.69–7.38 (m, 16 H, aryl), 7.49 (d, J = 2.7 Hz, 5-H, Pz), 7.52–7.91

Celite, and the filtrate reduced to a volume of 1 mL. Addition of

butanone (1 mL) followed by slow evaporation in the fume hood

(br. m, 2 H, aryl), 8.82 (q, J = 7.2 Hz, CHMe) ppm. ¹³C NMR gave yellow, rhombic crystals (67 mg, 65%), suitable for X-ray

1

(62.9 MHz, CDCl₃): δ = 18.4 (CH₃), 30.2 (CH₃), 31.9 (C), 56.8 (d,

J_P,C= 1 Hz, CH₃), 67.3 (d, J_P,C= 6 Hz, CH), 70.3 (d, J_P,C= 4 Hz, 34 Hz, 4 H, CH₂CH₂), 4.80 (m, AAЈ of AAЈBXXЈ, J_AB= J_AЈB

analysis. H NMR (250 MHz, CD₂Cl₂): δ = 2.28–2.62 (m, J_Pt,H

=

CH), 70.4 (CH, CpЈ), 73.6 (CH), 74.9 (d, J_P,C= 42 Hz, C, Cp), 93.5

(d, J_P,C= 18 Hz, C, Cp), 106.0 (CH), 120.9 (d, J_P,C= 1.5 Hz), 122.0

12.8 Hz, J_AX+ J_AXЈ= 22.1 Hz, J_Pt,H= 45.3 Hz, 2 allyl H, anti),

6.14 (t, B of AAЈBXXЈ, J = 12.8 Hz, J_Pt,H= 45 Hz, 1 allyl H,

(d, J_P,C= 1.0 Hz), 125.8 (CH), 126.2 (d, J_P,C= 7 Hz, CH), 127.0 central), 7.80–6.80 (m, 30 H, aryl) ppm. ¹³C NMR (62.9 MHz,

(d, J_P,C= 9 Hz, CH), 127.5 (d, J_P,C= 9 Hz, CH), 128.0 (d, J_P,C =

2 Hz, CH), 128.5 (CH), 129.2 (d, J_P,C= 56 Hz, C), 129.5 (d, J_P,C

2 Hz, CH), 131.3 (d, J_P,C= 10 Hz, CH), 131.6 (d, J_P,C= 44 Hz, C),

CD₂Cl₂): δ = 31.0 (AMMЈ, ψ-dd, J = 41 Hz, 9 Hz, J_Pt,C= 56 Hz,

CH₂), 83.5 [AMMЈ, ψ-d, J = 27 Hz, J_Pt,C= 55 Hz, CH, All-C(1,3)],

110.9 [A of AM₂, t, J_P,C= 4 Hz, J_Pt,CϷ 17 Hz, CH, All–C(2)],

=

135.9 (d, J_P,C= 10 Hz, CH), 137.7 (J_Pt,C= 38 Hz), 138.7 (C), 138.9 126.8 (AMMЈ, ψ-dd, J = 57 Hz, 0.8 Hz, J_Pt,C= 49 Hz, C, PPh-

(br.), 139.3 (C), 139.5 (br.), 143.0, 143.2, 144.6, 158.9, 160.8 ppm.

Some of the signals were not detected due to line broadening,

which arose from hindered rotation of the phenyl groups. ³¹P NMR

(101.3 MHz, CDCl₃): δ = 5.3 (s, J_Pt,P= 1688 Hz) ppm. MS (FAB):

ipso-C), 128.4 (AMMЈ, ψ-quint, J = 2 Hz, CH), 128.7 (AMMЈ, ψ-

dd, J = 56 Hz, 0.6 Hz, J_Pt,C= 38 Hz, C, PPh-ipso-C), 129.3

(AMMЈ, ψ-t, J = 1.5 Hz, CH), 130.3 (AMMЈ, ψ-t, J = 1.3 Hz,

CH), 131.1–131.6 (m, 2 CH), 133.7 (AMMЈ, CH), 133.8 (AMMЈ,

m/z (%) = 1584.8 (14) [2 M – 2 Ph]⁺, 868.4 (5) [M]⁺, 791.3 (12) J_Pt,C= 24 Hz, CH), 134.5 (AMMЈ, CH), 134.9 (AMMЈ, J_Pt,C

=

1408

www.eurjic.org

Eur. J. Inorg. Chem. 2006, 1397–1412

Cationic Palladium()- and Platinum()-η³-Allyl Complexes with Fluoride

25 Hz, CH), 137.7 (AMMЈ, C) ppm. Spin system nomenclature: A the color changed from violet to yellow, and a yellow solid precipi-

FULL PAPER

corresponds to the carbon atom in question, M and MЈ correspond

tated. After filtration, the solid was dried under HV. The product

could not be further purified and was only analyzed spectroscopi-

to the ³¹P nuclei. ³¹P NMR (101.3 MHz, CD₂Cl₂): δ = –143.7 (sept,

–

J_P,F= 711 Hz, PF₆), 44.7 (s, J_Pt,Pt= 3847 Hz) ppm. ¹⁹⁵Pt NMR cally for the presence of the (1,3-diphenylallyl)palladium() frag-

(HMQC, 64.2 MHz, CD₂Cl₂): δ = –5521 (t, J_Pt,PϷ 3830 Hz) ppm.

ment. ¹H NMR ([D₆]DMSO): δ = 5.29 [d, J = 12.0 Hz, 4 H,

MS (FAB): m/z (%) = 1717 (9) [2 M – PF₆]⁺, 786 (100) [M – PF₆]⁺, C(2),C(3)], 6.98 [t, J = 11.8 Hz, 2 H, C(2)], 7.39 (br. m, 12 H, aryl),

592 (10) [M – PF₆– Ph₂All]⁺. C₄₁H₃₇F₆P₃Pt (931.72): calcd. C

7.78 (br. m, 8 H, aryl) ppm. ¹⁹F NMR: no signal detected.

52.85, H 4.00; found C 52.83, H 4.14.

Di-µ-bromobis(η³-1,3-diphenylallyl)dipalladium(II) (27·Br): Pd(dba)₂

(40 mg, 0.070 mmol) and 15 (22.8 mg, 0.083 mmol) were stirred in

THF (20 mL) at room temp. The color of the violet suspension

became brighter within 20 min and a yellow precipitate was de-

posited. The solid was isolated by filtration and dried under HV.

No further purification was attempted due to the small scale of the

reaction. ¹H NMR ([D₆]DMSO): δ = 5.19 (d, J = 11.7 Hz, 4 H,

allyl H, anti), 6.80 (t, J = 11.7 Hz, 2 H, allyl H, central), 7.30–

7.27 (m, 12 H, aryl), 7.66–7.69 (m, 8 H, aryl) ppm. C₃₀H₂₆Br₂Pd₂

(759.18): calcd. C 47.46, H 3.45; found C 46.87, H 3.48.

(E)-1-Cyclohexyl-3-cyclohexylidenepropene (26): (a) The substance

was formed, in NMR experiments, from 8b and an excess of either

Me₄NF (in [D₃]MeCN) or Schwesinger’s P₂F^[57](in C₆D₆). (b) A

reference sample was obtained as follows: MsCl (56.0 mg,

0.488 mmol) was added dropwise at –78 °C to a solution of 10

(98.8 mg, 0.444 mmol) and iPr₂NEt (0.091 mL, 0.533 mmol) in

THF (5 mL). After stirring for 45 min and another addition of

iPr₂NEt (0.18 mL, 1.06 mmol) and MsCl (120 mg, 1 mmol) the re-

action mixture was warmed to room temp. and stirred for 2 h.

Workup with H₂O/tBuOMe gave, after drying (MgSO₄) and evapo-

ration to dryness, a residue that was filtered through SiO₂(tBu-

OMe) to yield 38.7 mg (42%) of a colorless oil. ¹H NMR

(250 MHz, CDCl₃): δ = 0.75–2.30 (m, 21 H-Cy), 5.54 (dd, J =

15.2 Hz, 7.0 Hz, 1-H), 5.73 (dd, J = 10.9 Hz, 0.7 Hz, 3-H), 6.25

Oxidative Addition of Ph₂AllF (6) to Pd(dba)₂in the Presence of

PPFPz{3,5-Me₂}

{Ǟ[Pd(η³-Ph₂All)(PPFPz{3,5-Me₂})]F·(H₂O)_n

(28·F)}: PPFPz{3,5-Me₂} (2c)^[28](54.2 mg, 0.11 mmol) and Pd(dba)₂

(57.5 mg, 0.10 mmol) were stirred in THF (10 mL) at 40 °C for

30 min to give an orange-brown solution. Ph₂AllF (6)^[14a](2 mL,

75 m in N,N-dimethylformamide, 0.15 mmol), was added and the

reaction mixture, which quickly turned yellow, was stirred for 1 h

at room temp. Solvents were removed under HV and the residue

purified by precipitation (in air) from CH₂Cl₂/pentane. ¹H NMR

(250 MHz, CDCl₃): δ = 0.71 (s, 3 H, Me-Pz), 1.67 (s, ca. 4 H, H₂O),

2.29 (d, J = 7.4 Hz, 3 H, CHMe), 2.31 (s, 3 H, Me–Pz), 3.75 (s, 1

H-Cp), 4.18 (s, 5 H, CpЈ); 4.35–4.37 (m, 1 H-Cp), 4.65 (s, 1 H-Cp),

5.30 (s, 1 H-Pz), 6.12–6.19 (m, 3 H, 1 allyl H,, 2 H, aryl), 6.43–

6.52 (m, 1 allyl H,), 6.98–8.03 (m, 19 H, 1 allyl H,, 18 H, aryl) ppm,

(ddd,

J =

15.2 Hz, 10.8 Hz, 1.2 Hz, 2-H) ppm. ¹³C NMR

(62.9 MHz, CDCl₃): δ = 26.1 (CH₂), 26.2 (CH₂), 26.8 (CH₂), 27.6

(CH₂), 28.4 (CH₂), 29.2 (CH₂), 33.1 (CH₂), 37.2 (CH₂), 41.0 (CH),

122.1 (CH), 123.2 (CH), 138.3 (CH), 141.2 (C) ppm. IR (CHCl₃):

ν = 2930 (s), 2853 (m), 1616 (w), 1448 (m), 1344 (w), 968 (m) cm^–1.

˜

MS (EI): m/z = 204 [M]⁺.

Oxidative Addition of Ph₂AllF (6) to Pd(dba)₂(Ǟ27·F): Pd(dba)₂

(170 mg, 0.29 mmol) and Ph₂AllF (6)^[14a](76 mg, 0.36 mmol, solu-

tion in 7 mL hexane) were stirred in THF (10 mL). Within 15 min,

Table 3. Crystallographic data for 8a, 8b, and 8c·CH₂Cl₂.

8a

8b

8c·CH₂Cl₂

CCDC number

Formula

M_r

Crystal system

Space group

a [Å]

b [Å]

c [Å]

α [°]

279485

C₄₆H₄₆F₆FeN₂P₂Pd

965.07

orthorhombic

P2₁2₁2₁

10.677(2)

19.505(3)

20.809(3)

90

279484

C₄₆H₅₈F₆FeN₂P₂Pd

977.13

orthorhombic

P2₁2₁2₁

10.3481(16)

17.276(3)

25.231(4)

90

279489

C₄₁H₄₂Cl₂F₆FeN₂P Pd Sb

1062.64

triclinic

P_1r

10.281(7)

15.338(10)

13.684(9)

90.0100(10)

92.1260(10)

2156(2)

β [°]

90

V [Å³]

4333.5(11)

4

1.479

0.884

1968

4510.7(12)

4

1.439

0.850

2016

Z

2

Density calcd. [Mg·m^–3]

µ [mm^–1]

F(000)

1.637

1.584

1056

Crystal size [mm³]

θ range (°)

Index ranges

0.94×0.34×0.16

1.43–28.31

–14 Յ h Յ 14

–25 Յ k Յ 26

–17 Յ l Յ 27

36689/10782

[R_int= 0.0672]

10782/0/523

0.964

R₁= 0.0349

wR₂= 0.0767

R₁= 0.0538

wR₂= 0.0837

–0.04(2)

0.50×0.44×0.28

1.43–24.78

–12 Յ h Յ 11

–20 Յ k Յ 20

–29 Յ l Յ 19

25274/7719

[R_int= 0.1009]

7719/42/509

0.949

R₁= 0.0589

wR₂= 0.1324

R₁= 0.0983

wR₂= 0.1489

–0.05(4)

0.80×0.54×0.26

1.33–29.69

–14 Յ h Յ 12

–18 Յ k Յ 21

–18 Յ l Յ 16

15564/12425

[R_int= 0.0365]

12425/3/994

1.062

R₁= 0.0457

wR₂= 0.1232

R₁= 0.0514

wR₂= 0.1338

–0.02(2)

Reflections collected/used

Data/restraints/parameters

Goodness-of-fit on F²

R indices

[I Ͼ 2σ(I)]

(all data)

Abs. struct. parameter

Largest diff. peak/hole [e·Å^–3]

0.490/–0.572

1.643/–0.750

0.829/–0.857

Eur. J. Inorg. Chem. 2006, 1397–1412

www.eurjic.org

1409

L. Hintermann, F. Läng, P. Maire, A. Togni

FULL PAPER

Table 4. Crystallographic data for 18·PF₆, 20·PhOH, and 24.

18·PF₆

20·PhOH

24

CCDC number

Formula

M_r

Crystal system

Space group

a [Å]

b [Å]

c [Å]

α [°]

279486

C₄₆H₄₆F₆FeN₂P₂Pt

1053.73

orthorhombic

P2₁2₁2₁

10.709(2)

19.566(3)

20.832(3)

90

279488

C₄₉H₄₉FeN₂OPPt

963.85

monoclinic

P2₁

11.591(14)

10.998(9)

16.464(3)

90

279487

C₄₁H₃₇F₆P₃Pt

931.71

orthorhombic

Pbca

18.525(7)

18.644(9)

22.108(9)

90

β [°]

90

4376.3(3)

4

1.599

3.658

94.72(9)

2092(4)

2

1.530

3.764

90

7636(6)

8

1.621

3.859

3680

0.2×0.17×0.13

1.80–20.15

0 Յ h Յ 17

0 Յ k Յ 17

0 Յ l Յ 21

3553/3553

[R_int= 0.0000]

3553/0/461

0.903

R₁= 0.0304

wR₂= 0.0752

R₁= 0.0455

wR₂= 0.0788

–

V [Å³]

Z

Density calcd. [Mg·m^–3]

µ [mm^–1]

F(000)

2096

968

Crystal size [mm³]

θ range (°)

Index ranges

0.95×0.3×0.3

1.43–29.96

–14 Յ h Յ 14

–18 Յ k Յ 27

–28 Յ l Յ 28

32667/11386

[R_int= 0.0683]

11386/0/524

0.945

R₁= 0.0405

wR₂= 0.0759

R₁= 0.0925

wR₂= 0.0897

–0.031(6)

1.164/–1.020

0.5×0.3×0.2

1.76–20.04

–11 Յ h Յ 11

–10 Յ k Յ 10

–15 Յ l Յ 15

3931/1989

–

1989/0/461

1.825

R₁= 0.036

wR₂= 0.033

R₁= 0.037

wR₂= 0.033

–

Reflections collected/used

Data/restraints/parameters

Goodness-of-fit on F²

R indices

[I Ͼ 2σ(I)]

(all data)

Abs. struct. parameter

Largest diff. peak/hole [e·Å^–3]

0.754/–1.179

0.561/–0.637

peaks broadened. ¹⁹F NMR (282.4 MHz, CDCl₃): no signal de-

hard Raabe, Michael Wörle, and Stefan Zürcher. Daniel Whelligan

tected. ³¹P NMR (CDCl₃): δ = 12.1 (br. s) ppm. C₄₄H₄₂FFeN₂PPd is thanked for eliminating English glitches.

+ 3H₂O (865.10): calcd. C 61.09, H 5.59, N 3.24; found C 61.02,

H 5.09, N 2.77.

[1] M. N. Doherty, N. W. Hoffmann, Chem. Rev. 1991, 91, 553.

X-ray Crystallography: Data were collected at 293 K with a Sie-

mens SMART CCD diffractometer (graphite-monochromated Mo-

[2] E. F. Murphy, H. W. Roesky, Chem. Rev. 1997, 97, 3425.

[3] S. Thrasher, S. H. Strauss, Inorganic Fluorine Chemistry towards

the 21st Century, American Chemical Society, Washington,

DC, 1994.

K_αradiation,

λ = 0.71073 Å, ω-scan technique), except for

20·PhOH and 24, for which the data was collected with a Syntex

P21 4-circle diffractometer. The structures were solved by direct

methods using SHELXS-97.^[69]A full matrix least-squares refine-

ment on F²was performed with SHELXL-97.^[70]Allyl fragments

in 8b and the phenol solvate in 20·PhOH were refined isotropically,

all other non-hydrogen atoms were refined anisotropically. The hy-

drogen atoms were placed in calculated positions and assigned

using an isotropic displacement parameter of 0.08 Å². SADABS^[71]

was used to perform area-detector scaling and absorption correc-

tions. No absorption correction was applied for 20·PhOH and 24.

[4] H. Plenio, Chem. Rev. 1997, 97, 3363.

[5] J. L. Kiplinger, T. G. Richmond, C. E. Osterberg, Chem. Rev.

1994, 94, 373.

[6] a) J. Burdeniuc, B. Jedlicka, R. H. Crabtree, Chem. Ber./Recueil

1997, 130, 145; b) M. Aizenberg, D. Milstein, Science 1994,

265, 359.

[7] a) K. Fagnou, M. Lautens, Angew. Chem. 2002, 114, 26; Angew.

Chem. Int. Ed. 2002, 41, 26; b) B. L. Pagenkopf, E. M. Car-

reira, Chem. Eur. J. 1999, 5, 3437.

[8] U. Burckhardt, M. Baumann, A. Togni, Tetrahedron: Asym-

metry 1997, 8, 155.

CCDC-279484 to -279489 (cf. Table 3 and Table 4) contain the sup-

plementary crystallographic data for this paper. This data can be

obtained free of charge from The Cambridge Crystallographic

Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

[9] a) A. L. Henne, T. H. Newby, J. Am. Chem. Soc. 1948, 70, 130;

b) A. L. Henne, A. M. Whaley, J. K. Stevenson, J. Am. Chem.

Soc. 1941, 63, 3478; c) A. L. Henne, Org. React. 1944, 2, 49.

[10] Fluorocarbonylations: a) T. Okano, N. Harada, J. Kiji, Chem.

Lett. 1994, 1057; b) T. Okano, N. Harada, J. Kiji, Bull. Chem.

Soc. Jpn. 1992, 65, 1741; c) T. Sakakura, M. Chaisupakitsin,

T. Hayashi, M. Tanaka, J. Organomet. Chem. 1987, 334, 205.

[11] Additional examples of transition-metal catalyzed or mediated

fluorinations: a) R. D. Chambers, J. Hutchinson, J. Fluorine

Chem. 1998, 92, 45; b) S. Bruns, G. Haufe, J. Fluorine Chem.

2000, 104, 247.

Acknowledgments

L. H. thanks Solvias AG, Basel, for a Ph.D. grant, the Deutsche

Forschungsgemeinschaft for current support with an Emmy No-

ether Programm, and Prof. C. Bolm for continued support. Credit

for crystallographic measurements, preliminary structure solutions,

data shuffling, and final solutions goes to Diego Broggini, Ulli En-

glert, Céline Gambs, Volker Gramlich, Arianna Martelletti, Ger-

[12] V. V. Grushin, Chem. Eur. J. 2002, 8, 1006.

[13] a) M. Shimizu, T. Hiyama, Angew. Chem. 2005, 117, 218; An-

gew. Chem. Int. Ed. 2005, 44, 214; b) P. Kirsch, Modern Fluo-

roorganic Chemistry, Wiley-VCH, Weinheim, 2004; c) T. Hi-

1410

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Eur. J. Inorg. Chem. 2006, 1397–1412

Cationic Palladium()- and Platinum()-η³-Allyl Complexes with Fluoride

FULL PAPER

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Received: September 8, 2005

Published Online: February 9, 2006

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www.eurjic.org

Eur. J. Inorg. Chem. 2006, 1397–1412

Article Doi

Interactions of cationic palladium(II)- and platinum(II)-η3- allyl complexes with fluoride: Is asymmetric allylic fluorination a viable reaction?

DOI: 10.1002/ejic.200500795

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