Chiral chelate phosphanes: XI. Application of cyclopentane-based C2 chiral bis(phosphane) ligands C5H8(PR2)2 to Pt-Sn-catalyzed styrene hydroformylation

Journal of Organometallic Chemistry 630 (2001) 221–243

www.elsevier.com/locate/jorganchem

Chiral chelate phosphanes^ꢀ

XI. Application of cyclopentane-based C₂chiral bis(phosphane)

ligands C₅H₈(PR₂)₂to PtꢀSn-catalyzed styrene hydroformylation

Lutz Dahlenburg *, Stefan Mertel

Institut fu¨r Anorganische Chemie der Friedrich-Alexander-Uni6ersita¨t Erlangen-Nu¨rnberg, Egerlandstrasse 1, D-91058 Erlangen, Germany

Received 7 March 2001; accepted 14 March 2001

Dedicated to Professor Dr Dieter Sellmann on the occasion of his 60th birthday.

Abstract

Treatment of [(1,5-C₈H₁₂)PtCl(X)] (X=Cl, CH₃, CH₂CMe₃) with C₂chiral cyclopentane-1,2-diyl-bis(phosphanes) C₅H₈(PR₂)₂,

either as racemic mixtures or as resolved enantiomers, afforded the chelate complexes [C₅H₈(PR₂)₂Pt(Cl)(X)] (X=Cl: R=Ph (1),

N-pip (2), OPh (3); X=CH₃: R=Ph (4), N-pip (5), OPh (6); X=CH₂CMe₃: R=Ph (7), N-pip (8), OPh (9); ‘N-pip’=N(CH₂)₅),

(+)-[(1R,2R)-C₅H₈{P(OPh)₂}₂PtCl₂]

[(R,R)-3],

(−)-[(1S,2S)-C₅H₈{P(OPh)₂}₂PtCl₂]

[(S,S)-3],

(−)-[(1R,2R)-

C₅H₈(PPh₂)₂Pt(Cl)(X)], and (+)-[(1S,2S)-C₅H₈(PPh₂)₂Pt(Cl)(X)] (X=CH₃: (R,R)-4, (S,S)-4; X=CH₂CMe₃: (R,R)-7, (S,S)-7).

Reacting 4, 6, and 7 with AgO₃SCF₃led to triﬂate derivatives [C₅H₈(PR₂)₂Pt(X)(OSO₂CF₃)] [X=CH₃: R=Ph (11), OPh (12);

X=CH₂CMe₃: R=Ph (13)] with covalently bonded OSO₂CF₃ligands. The unusual Pt₂complex [m-

Cl{C₅H₈(PPh₂)₂PtCH₃}₂]O₃SCF₃(14) containing an unsupported single PtꢀClꢀPt bridge was also isolated. In the presence of

SnCl₂, complexes 1, 3, 4, 6, 7, and 9 are catalysts for the hydroformylation of styrene forming 2- and 3-phenylpropanal together

with ethylbenzene. Except for 1, they also catalyze the consecutive hydrogenation of the primary propanals to alcohols. High

regioselectivities towards 2-phenylpropanal (branched-to-normal ratios ]91:9) were obtained in hydroformylations catalyzed by

3 and 4, for which the inﬂuence of varied CO/H₂partial pressures, catalyst-to-substrate ratios and different reaction temperatures

and times on the outcome of the catalytic reaction was also studied. When tin-modiﬁed complexes (R,R)-3, (S,S)-3, and (S,S)-4

were used as optically active Pt(II) catalysts, an only low stereoselectivity for asymmetric hydroformylation (e.e.B18%) was

observed. The PtꢀSn complexes [C₅H₈(PR₂)₂Pt(CH₃)(SnCl₃)] [R=Ph (15), OPh (17)], resulting from SnCl₂insertion into the PtꢀCl

bonds of 4 or 6, undergo rapid degradation in solution, forming mixtures composed of [C₅H₈(PR₂)₂Pt(X)(Y)] with R=Ph or OPh

and X/Y=Cl/SnCl₃(16, 18), Cl/Cl (1, 3), and SnCl₃/SnCl₃(19, 20), respectively. In the presence of SnCl₂, triﬂate complex 11 also

becomes a catalyst for styrene hydroformylation and consecutive hydrogenation of the aldehydes to alcohols. The crystal

structures of 11 complexes — 2, 5, 7, 8, 9, 10 (the previously prepared [C₅H₈{P(N-pip)₂}₂Pt(CH₂CMe₃)₂]), 13, 14, 16, (R,R)-3,

Keywords: Chirality; P ligands; Platinum; Catalysis; Hydroformylation; X-Ray structure analysis

1. Introduction

provided that the chemo-, regio- and enantioselectivity

all prove to be excellent [2]. In pioneering contributions

by Pittman, Consiglio, and Stille [3,4] and, more re-

cently, in a communication by Csere´pi-Szu¨cs and Bakos

[5a], good to very high enantiomeric excesses of

branched aldehydes could be attained with SnCl₂-acti-

vated [{bis(phosphane)}PtCl₂] and [{bis(phosphite)}-

PtCl₂] catalyst systems. In contrast to the extremely

successful Rh-based systems utilizing chiral bidentate

bis(phosphites) or phosphane–phosphites as supporting

Asymmetric hydroformylation of prochiral oleﬁns

such as vinyl arenes is potentially a very powerful tool

for the synthesis of enantiomerically pure aldehydes,

^ꢀPart X: [1].

* Corresponding author. Tel.: +49-9131-85-27353; fax: +49-

9131-85-27387.

E-mail address: dahlenburg@chemie.uni-erlangen.de (L. Dahlen-

burg).

PII: S0022-328X(01)01001-4

222

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

ligands [2d,6,7,8,9,10], PtꢀSn catalysts exhibiting high

enantioselectivities, however, frequently suffer from low

or, at best, moderate regioselectivities and the forma-

tion of substantial amounts of undesired hydrogenation

products [2b], [{(R,R)-bco-dpb}PtCl₂]ꢀSnCl₂[3c] being

a noteworthy exception (bco-dpb is {bicyclo[2.2.2]-

octane - 3,4 - diyl - bis(methylene)}bis(5H - benzo[b]phos-

phindole). Conversely, high regioselectivities towards

branched aldehydes but low optical and chemical yields

were obtained with platinum–tin catalytic systems sup-

ported by bis(phosphite) ligands containing binaphthyl

[5b] and, respectively, carbohydrate [11] backbones.

A large part of our current research is focused on

bidentate phosphorus ligands of the type C₅H₈(PR₂)₂

(R=C-, N-, or O-bonded group) bearing differently

substituted and, hence, ﬁne-tunable donor sets sup-

ported on a C₂chiral 1,2-trans-disubstituted cyclopen-

tane framework [12,13]. Use of such ligands in

transition metal-mediated asymmetric catalysis can

provide insight into the relations and regularities exist-

ing between the performance of the catalytic system

and the stereoelectronic properties of the active metal–

ligand template [13h,14]. One aspect of the work re-

ported in this communication was to elucidate how the

chemo- and regioselectivities of styrene hydroformyla-

tion reactions are affected by differently substituted

catalysts of the type [C₅H₈(PR₂)₂Pt(Cl)(X)]ꢀSnCl₂with

R=phenyl, N(CH₂)₅(‘N-pip’), or phenoxy, and X=

Cl, CH₃, or CH₂CMe₃, respectively. Throughout these

exploratory studies, the phosphorus ligands were em-

ployed as racemic mixtures. The capacity for enantio-

face discrimination was only investigated for selected

optically active [C₅H₈(PR₂)₂Pt(Cl)(X)]ꢀSnCl₂catalysts

featuring acceptable chemo- and regioselectivities. To

the best of our knowledge, chiral bis(phosphonites) as

represented by C₅H₈[P(OR)₂]₂, so far have not been

utilized as supporting ligands for asymmetric oleﬁn

hydroformylation [15], in contrast to phosphites (vide

supra) and phosphinites [16].

[{bis(phosphane)}Pt(h²-C₂H₄)] become active hydro-

formylation catalysts [25], if in situ promoted to either

[{bis(phosphane)}Pt(h²-CH₂CH₂ꢀH)]O₃SCF₃

or

[{bis(phosphane)}Pt(X)OSO₂CH₃] (X=H, C₂H₅) [28]

by methanesulfonic acid. These observations and the

interest in tin-free hydroformylation catalysts based on

platinum [21–23,25] prompted us to also probe

[C₅H₈(PPh₂)₂Pt(CH₃)(OSO₂CF₃)] as an exemplary triﬂ-

ate-containing complex for its hydroformylation activ-

ity. Recently,

a

decrease in activity and

enantioselectivity but an increase in regioselectivity to-

wards the chiral branched aldehyde was observed for

homogeneous [{bis(phosphane)}PtCl₂]ꢀSnCl₂catalysts

modiﬁed by triﬂate additives [20d].

2. Results and discussion

2.1. Racemic chloro complexes and triﬂate deri6ati6es:

preparation and structures

The chelate complexes [C₅H₈(PR₂)₂Pt(Cl)(X)] [X=

Cl: R=Ph (1), N-pip (2), OPh (3); X=CH₃: R=Ph

(4), N-pip (5), OPh (6); X=CH₂CMe₃: R=Ph (7),

N-pip (8), OPh (9); see Scheme 1] were synthesized by

reacting the corresponding P₂ligand with the requisite

1,5-cyclooctadiene precursor [(1,5-C₈H₁₂)Pt(Cl)(X)]

(X=Cl [33a,33c], CH₃[33b], CH₂CMe₃[33d]) in 1:1

stoichiometry in dichloromethane at ambient condi-

tions, similar to the procedures previously described for

8 and related dineopentyls such as, e.g. [C₅H₈{P(N-

pip)₂}₂Pt(CH₂CMe₃)₂] (10) [13d].

Satisfactory yields of the triﬂate derivatives

[C₅H₈(PR₂)₂Pt(X)(OSO₂CF₃)] [X=CH₃: R=Ph (11),

OPh (12); X=CH₂CMe₃: R=Ph (13)] resulted from

the addition, at room temperature, of compounds 4, 6,

and 7 to solution-suspensions of equimolar quantities

of AgO₃SCF₃in dichloromethane. If the reactants were

combined in the reversed order at low temperature,

unchanged starting complex readily displaced the

CF₃SO⁻₃ligand from the triﬂate product already

formed, producing chloro-bridged [m-Cl{C₅H₈(PR₂)₂-

PtX}₂]O₃SCF₃, as exempliﬁed by [m-Cl{C₅H₈(PPh₂)₂-

PtCH₃}₂]O₃SCF₃(14), which was isolated on adding

one equivalent of silver triﬂate in portions to a CH₂Cl₂

solution of [C₅H₈(PPh₂)₂Pt(Cl)(CH₃)] (4) kept at

−60 °C.

The role of the SnCl₂or SnCl⁻₃additive in the

PtꢀSn-catalyzed hydroformylation reaction [17–20] still

remains somewhat ambiguous. Thus, catalytic systems

have been developed [21–25] whose performance casts

doubt upon the function of the trichlorostannate group

as an indispensable Pt-bonded ligand, and ample evi-

dence has been presented which strongly supports the

interpretation of the primary role of the SnCl⁻₃ion as

that of a good leaving group, favoring CO activation

and Pt–acyl formation in cationic platinum complexes

[17,20a,20b]. Sulfonic acid anions RSO⁻₃(R=CH₃,

CF₃, F) represent other examples of good leaving

groups whose coordination behavior toward, e.g. Pt(II)

is well known to vacillate between that of a moderate-

to-good metal-bonded ligand and that of a cation-stabi-

lizing non-bonded counter-ion [26–32]. It is therefore

not surprising to see that alkene platinum(0) complexes

The ³¹P{¹H}-NMR spectra of the dichloro and (al-

kyl)chloro or (alkyl)sulfonato complexes displayed the

expected ¹⁹⁵Pt-ﬂanked A₂and AB resonances requiring

no further discussion. Due to the lack of a molecular

mirror plane bisecting the RꢀPꢀR angles of the prochi-

ral ꢀPR₂groups, the phenyl, piperidino, and phenoxy

carbon atoms of the substituents become pairwise

diastereotopic and are found to be sufﬁciently different

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

223

for their nonequivalence to be detected in the 75.5 MHz

¹³C{¹H}-NMR spectra. Except for the unique methyl-

ene carbon C-4 of the cyclopentane backbone, each of

the ¹³C nuclei of the ligands gives rise to a spin system

of the AA%X or ABX limiting type, A/A% and A/B

representing the two (with respect to ¹³C) magnetically

non-equivalent ³¹P nuclei of molecules [C₅H₈(PR₂)₂-

PtCl₂] or [C₅H₈(PR₂)₂Pt(X)(Y)] [34,35]. In the com-

plexes studied, these spin systems exhibit practically all

the possible multiplicities that can arise for the associ-

ated X part sub-spectra, depending on the magnitude of

the various P,C and P,P couplings between the nuclei

involved [34] (see Section 4).

The molecular structures of eight of the compounds

prepared as outlined before, including the previously

described complexes 8 and 10 [13d], were determined by

single-crystal X-ray diffraction and are shown in Figs.

1–8, selected bond lengths and valence and torsion

angles being collected in the legends.

Fig. 1. Molecular structure of [C₅H₈{P(N-pip)₂}₂PtCl₂], 2. Selected

,

bond lengths (A) and valence and torsion angles (°): PtꢀCl, 2.395(1);

PtꢀP, 2.226(1). ClꢀPtꢀCl 1, 90.96(7); ClꢀPtꢀP, 90.81(5), ClꢀPtꢀP 1,

–

174.61(8); PꢀPtꢀP 1, 87.90(8).

P

1ꢀPtꢀPꢀN(1), 110.1(3);

P

–

1ꢀPtꢀPꢀN(2), −127.6(3). Operators for generating equivalent atoms

Cl 1 and P 1: −x+¹₄, y, −z+₄³.

–

Fig. 2. Molecular structure of [C₅H₈{P(N-pip)₂}₂Pt(Cl)(CH₃)], 5.

,

Selected bond lengths (A) and valence and torsion angles (°): PtꢀCl,

2.383(6); PtꢀP(1), 2.276(6); PtꢀP(2), 2.213(6); PtꢀC(1), 2.206(16).

ClꢀPtꢀP(1), 95.0(2); ClꢀPtꢀP(2), 171.4(2); ClꢀPtꢀC(1), 84.5(5);

P(1)ꢀPtꢀP(2), 87.8(2); P(1)ꢀPtꢀC(1), 173.9(5); P(2)ꢀPtꢀC(1), 93.6(4).

P(1)ꢀPtꢀP(2)ꢀN(3),

108.6(8);

P(1)ꢀPtꢀP(2)ꢀN(4),

−125.0(8);

P(2)ꢀPtꢀP(1)ꢀN(1), 105.2(8); P(2)ꢀPtꢀP(1)ꢀN(2), −131.6(8).

The molecules show the expected planar coordina-

tion geometry about the central platinum atom as

evidenced from: (i) the sum of the four intra- and

interligand cis angles, found in the narrow range from

359.5 to 360.9°, and (ii) from the angles between the

normals to the two planes deﬁned by the PtP₂and

Pt(X)(Y) fragments. These dihedral angles lie between

2.9° (planes at Pt(1) in 14) and 8.6° (complex 8) and

thus deviate only little from the ideal value of 0°

required for an undistorted planar surrounding of the

metal atom. As observed in earlier work for four re-

lated Pt(II) complexes bearing C₅H₈(PR₂)₂ligands

Scheme 1. Complexes and reactions studied.

224

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

[13d], the PꢀPtꢀP bite-angles, ranging from 85.3 to

88.2°, show only a small degree of scattering.

The PtꢀP bond lengths vary between 2.181 and 2.226

,

A for chloride or triﬂate as weak trans inﬂuencing

ligands and reveal no discernible dependence on the

nature of the substituents on phosphorus. For some of

the complexes studied, the lengths of the PtꢀP bonds

opposite the strongly trans bond-weakening methyl or

neopentyl groups tend to be slightly shorter in

molecules containing PꢀN- or PꢀO-substituted chelat-

Fig. 5. Molecular structure of [C₅H₈{P(OPh)₂}₂Pt(Cl)(CH₂CMe₃)], 9.

,

Selected bond lengths (A) and valence and torsion angles (°):

Pt(1)ꢀCl(1), 2.359(1); Pt(1)ꢀP(1), 2.277(1); Pt(1)ꢀP(2), 2.181(1);

Pt(1)ꢀC(1), 2.108(5). Cl(1)ꢀPt(1)ꢀP(1), 90.99(5); Cl(1)ꢀPt(1)ꢀP(2),

172.73(5); Cl(1)ꢀPt(1)ꢀC(1), 88.8(2); P(1)ꢀPt(1)ꢀP(2), 85.26(5);

P(1)ꢀPt(1)ꢀC(1), 177.9(2); P(2)ꢀPt(1)ꢀC(1), 95.2(2). P(1)ꢀPt(1)ꢀ

P(2)ꢀO(3), −97.5(2); P(1)ꢀPt(1)ꢀP(2)ꢀO(4), 136.4(2); P(2)ꢀPt(1)ꢀ

P(1)ꢀO(1), −106.0(2); P(2)ꢀPt(1)ꢀP(1)ꢀO(2), 131.3(2).

Fig. 3. Molecular structure of [C₅H₈(PPh₂)₂Pt(Cl)(CH₂CMe₃)], 7.

,

Selected bond lengths (A) and valence and torsion angles (°): PtꢀCl,

2.369(1); PtꢀP(1), 2.344(1); PtꢀP(2), 2.208(1); PtꢀC(1), 2.101(5).

ClꢀPtꢀP(1), 91.65(5); ClꢀPtꢀP(2), 173.52(7); ClꢀPtꢀC(1), 87.8(1);

P(1)ꢀPtꢀP(2), 86.74(5); P(1)ꢀPtꢀC(1), 175.6(2); P(2)ꢀPtꢀC(1), 93.3(1).

P(1)ꢀPtꢀP(2)ꢀC(11),

−140.0(2);

P(1)ꢀPtꢀP(2)ꢀC(17),

90.5(2);

P(2)ꢀPtꢀP(1)ꢀC(23), 110.6(2); P(2)ꢀPtꢀP(1)ꢀC(29), −124.9(2).

Fig. 6. Molecular structure of [C₅H₈{P(N-pip)₂}₂Pt(CH₂CMe₃)₂] (10)

showing the twofold spatial disorder of ring atoms C(6a) and C(6b).

,

Selected bond lengths (A) and valence and torsion angles (°):

Pt(1)ꢀP(1), 2.285(1); Pt(1)ꢀC(1), 2.135(5). P(1)ꢀPt(1)ꢀP(1) 1,

–

86.38(7); P(1)ꢀPt(1)ꢀC(1), 90.4(1); P(1)ꢀPt(1)ꢀC(1) 1, 176.3(1);

–

C(1)ꢀPt(1)ꢀC(1) 1, 92.8(3). P(1) 1ꢀPt(1)ꢀP(1)ꢀN(1), 125.2(2); P(1)

–

1ꢀPt(1)ꢀP(1)ꢀN(2), −110.9(2). Operators for generating equivalent

atoms P(1) 1 and C(1) 1: −x, y, −z+¹₂.

–

,

ing ligands (5, 9, 10: d(PtꢀP), 2.276(6)–2.285(1) A; cf.

,

2.253(4)–2.307(3) A for three similar compounds hav-

Fig. 4. Molecular structure of [C₅H₈{P(N-pip)₂}₂Pt(Cl)(CH₂CMe₃)],

ing ꢀP(NR₂)₂or ꢀP(OR)₂trans to neopentyl [13d]) than

in those (7, 13) derived from the PꢀC-bonded

C₅H₈(PPh₂)₂chelate system, where the corresponding

,

8. Selected bond lengths (A) and valence and torsion angles (°):

Pt(1)ꢀCl(1), 2.393(1); Pt(1)ꢀP(1), 2.206(1); Pt(1)ꢀP(2), 2.327(2);

Pt(1)ꢀC(1), 2.114(5). Cl(1)ꢀPt(1)ꢀP(1), 171.38(6); Cl(1)ꢀPt(1)ꢀP(2),

92.58(5); Cl(1)ꢀPt(1)ꢀC(1), 86.5(1); P(1)ꢀPt(1)ꢀP(2), 85.94(5);

P(1)ꢀPt(1)ꢀC(1), 94.7(1); P(2)ꢀPt(1)ꢀC(1), 178.0(2). P(1)ꢀPt(1)ꢀ

P(2)ꢀN(3), −121.3(2); P(1)ꢀPt(1)ꢀP(2)ꢀN(4), 111.0(2); P(2)ꢀPt(1)ꢀ

P(1)ꢀN(1), 144.4(2); P(2)ꢀPt(1)ꢀP(1)ꢀN(2), −87.5(2).

,

PtꢀP bonds are elongated to 2.344(1) and 2.346(2) A,

respectively. It is, however, questionable whether these

differences mirror any meaningful inﬂuence of the indi-

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

225

vidual P-substituents on the bond lengths, since the

PtꢀP distances trans to the alkyl groups in [C₅H₈{P(N-

,

pip)₂}₂Pt(Cl)(CH₂CMe₃)] (8), 2.327(2) A, and [m-

Cl{C₅H₈(PPh₂)₂PtCH₃}₂]O₃SCF₃(14), 2.312(3) and

,

2.325(2) A, do not differ signiﬁcantly. The non-bridging

PtꢀCl distances fall within the narrow range 2.383(1)–

,

A for the complexes derived from the

2.395(1)

,

C₅H₈[P(N-pip)₂]₂ligand (2, 5, 8), but are 2.359(1) A for

the P-phenoxy-substituted molecule 9 and 2.346(2) and

,

2.366(2)

A

for two similar complexes having

C₅H₈[P(OR)₂]₂ligands [13d]. However, as with the PtꢀP

bond lengths discussed before, these variations should

not be overestimated as the length of the PtꢀCl bond

trans to PPh₂in [C₅H₈(PPh₂)₂Pt(Cl)(CH₂CMe₃)] (7),

,

2.369(1) A, is very close to those of the molecules

having P(OR)₂donor sets opposite PtꢀCl. The PtꢀC

Fig. 8. Molecular structure of the binuclear cation of [m-

Cl{C₅H₈(PPh₂)₂PtCH₃}₂]O₃SCF₃(14); meso form shown; spatially

disordered positions (2a), (2b), (32a), and (32b) of carbon atoms C(2),

,

distances, 2.093(8)–2.206(16) A, measured for the two

methyl (5, 14) and the ﬁve neopentyl (7–10, 13) deriva-

,

C(3), C(32), and C(33) omitted for clarity. Selected bond lengths (A)

,

tives fall within the range from 2.02 to 2.22 A typically

and valence and torsion angles (°): Pt(1)ꢀCl(1), 2.405(2); Pt(1)ꢀP(1),

2.192(3); Pt(1)ꢀP(2), 2.325(2); Pt(1)ꢀC(1), 2.093(8); Pt(2)ꢀCl(1),

2.399(2); Pt(2)ꢀP(3), 2.190(3); Pt(2)ꢀP(4), 2.312(3); Pt(2)ꢀC(31),

2.113(9). Pt(1)ꢀCl(1)ꢀPt(2), 120.2(1); Cl(1)ꢀPt(1)ꢀP(1), 177.97(8);

Cl(1)ꢀPt(1)ꢀP(2), 89.85(9); Cl(1)ꢀPt(1)ꢀC(1), 92.5(3); P(1)ꢀPt(1)ꢀP(2),

88.25(10); P(1)ꢀPt(1)ꢀC(1), 89.4(3); P(2)ꢀPt(1)ꢀC(1), 176.3(3);

spanned by Ptꢀsp³-C bonds in organo complexes

adopting approximately square-planar coordination ge-

ometry at platinum [36], the longer distances occurring

when the alkyl group is facing a relatively strong trans

Cl(1)ꢀPt(2)ꢀP(3),

176.96(10);

Cl(1)ꢀPt(2)ꢀP(4),

93.04(8);

Cl(1)ꢀPt(2)ꢀC(31), 88.1(3); P(3)ꢀPt(2)ꢀP(4), 87.99(9); P(3)ꢀPt(2)ꢀ

C(31), 90.7(3); P(4)ꢀPt(2)ꢀC(31), 176.9(3). P(2)ꢀPt(1)ꢀCl(1)ꢀPt(2),

172.2(1); C(1)ꢀPt(1)ꢀCl(1)ꢀPt(2), −4.9(3); P(4)ꢀPt(2)ꢀCl(1)ꢀPt(1),

−111.2(1); C(31)ꢀPt(2)ꢀCl(1)ꢀPt(1), 71.7(3); P(1)ꢀPt(1)ꢀP(2)ꢀC(19),

−124.6(3); P(1)ꢀPt(1)ꢀP(2)ꢀC(25), 111.0(2); P(2)ꢀPt(1)ꢀP(1)ꢀC(7),

125.4(3); P(2)ꢀPt(1)ꢀP(1)ꢀC(13), −111.2(2); P(3)ꢀPt(2)ꢀP(4)ꢀC(37),

−112.4(2); P(3)ꢀPt(2)ꢀP(4)ꢀC(43), 124.0(3); P(4)ꢀPt(2)ꢀP(3)ꢀC(49),

109.7(2); P(4)ꢀPt(2)ꢀP(3)ꢀC(55), −126.5(3).

inﬂuence ligand, such as a P donor. The PtꢀOSO₂CF₃

,

distance in 13, 2.173(5) A, is signiﬁcantly longer than

,

that

of

2.090(6)

A

earlier

reported

for

[{(C₂F₅)₂P(CH₂)₂P(C₂F₅)₂}Pt(CH₃)(OSO₂CF₃)], featur-

ing an unusually strong interaction between the triﬂate

ligand and the electrophilic metal center [31], but com-

,

pares well to the value of 2.181(9) A measured for

[{Bu^t₂P(CH₂)₃PBu₂^t}Pt(H)(OSO₂CF₃)] [28b].

In the strictly C₂symmetric molecules [C₅H₈{P(N-

pip)₂}₂PtCl₂] (2) and C₅H₈{P(N-pip)₂}₂Pt(CH₂CMe₃)₂]

(10), the PꢀPtꢀPꢀN torsion angles are close to 110° for

an ‘equatorial’ alignment of the piperidino groups with

respect to the coordination plane and become (with

opposite sign) 125–127° for an ‘axial’ disposition,

thereby indicating little axial-equatorial differentiation

for the spatial orientation of these P-substituents. For

the complexes having unlike anionic ligands attached to

platinum, a similar situation is encountered for the PR₂

groups cis to chloride or methyl, where the PꢀPtꢀPꢀR

torsion angles amount to 105–112° and 124–132°, re-

spectively. In the neopentyl derivatives 7–9 and 13, on

the other hand, the spatial arrangements of residues R

in the PR₂groups cis to the very bulky CH₂CMe₃

Fig. 7. Molecular structure of [C₅H₈(PPh₂)₂Pt(CH₂CMe₃)-

,

(OSO₂CF₃)], 13. Selected bond lengths (A) and valence and torsion

angles (°): Pt(1)ꢀP(1), 2.346(2); Pt(1)ꢀP(2), 2.189(2); Pt(1)ꢀO(1),

2.173(5); Pt(1)ꢀC(1), 2.105(7); S(1)ꢀO(1), 1.458(6); S(1)ꢀO(2),

1.403(7); S(1)ꢀO(3), 1.422(7); S(1)ꢀC(35), 1.81(1); C(35)ꢀF(1), 1.29(1);

C(35)ꢀF(2), 1.30(1); C(35)ꢀF(3), 1.33(1). P(1)ꢀPt(1)ꢀP(2), 86.28(8);

P(1)ꢀPt(1)ꢀO(1), 89.2(1); P(1)ꢀPt(1)ꢀC(1), 178.1(2); P(2)ꢀPt(1)ꢀO(1),

174.4(2); P(2)ꢀPt(1)ꢀC(1), 95.6(2); O(1)ꢀPt(1)ꢀC(1), 89.0(3);

Pt(1)ꢀO(1)ꢀS(1), 131.0(3); O(1)ꢀS(1)ꢀO(2), 114.7(4); O(1)ꢀS(1)ꢀO(3),

112.5(4); O(2)ꢀS(1)ꢀO(3), 117.6(5); O(1)ꢀS(1)ꢀC(35), 101.5(4);

O(2)ꢀS(1)ꢀC(35), 104.4(5); O(3)ꢀS(1)ꢀC(35), 103.6(5); S(1)ꢀC(35)ꢀ

F(1), 112.9(7); S(1)ꢀC(35)ꢀF(2), 111.7(7); S(1)ꢀC(35)ꢀF(3), 110.4(8);

F(1)ꢀC(35)ꢀF(2), 108.4(10); F(1)ꢀC(35)ꢀF(3), 108.0(9); F(2)ꢀC(35)ꢀ

F(3), 105.1(8). P(1)ꢀPt(1)ꢀP(2)ꢀC(23), −83.1(3); P(1)ꢀPt(1)ꢀ

P(2)ꢀC(29), 147.2(3); P(2)ꢀPt(1)ꢀP(1)ꢀC(11), 110.4(3); P(2)ꢀPt(1)ꢀ

P(1)ꢀC(17), −123.3(3).

226

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

2.2. Racemic [C₅H₈(PR₂)₂Pt(Cl)(X)]ꢀSnCl₂catalysts

(X=Cl, alkyl): styrene hydroformylation under

different reaction conditions and related chemistry

ligand differ signiﬁcantly, the PꢀPtꢀPꢀR torsion angles

varying from 83 to 97° for the axial disposition and

(again with opposite sign) from 136 to 147° for the

equatorial orientation.

The preformed dichloro and alkyl(chloro) complexes

[C₅H₈(PPh₂)₂Pt(Cl)(X)] [X=Cl (1), CH₃(4), CH₂CMe₃

(7)], [C₅H₈{P(N-pip)₂}₂Pt(Cl)(X)] [X=CH₃(5),

CH₂CMe₃(8)], and [C₅H₈{P(OPh)₂}₂Pt(Cl)(X)] [X=Cl

(3), CH₃(6), CH₂CMe₃(9)] were inspected for their

performance as catalysts of the PtꢀSn-promoted hydro-

formylation of styrene as model substrate. [C₅H₈{P(N-

pip)₂}₂PtCl₂] (2) was excluded from these studies

because of its limited solubility. In these probing reac-

tions, which were run for 66 h at typical platinum-to-

oleﬁn ratios of 1:170–1:180, in the presence of two

equivalents of added anhydrous SnCl₂, in toluene solu-

tions heated at 80 °C under 80 bar of a 1:1 CO–H₂

synthesis gas mixture, the use of SnCl₂-modiﬁed P-

piperidino-substituted complexes 5 and 8 as catalysts

led to good aldehyde selectivities (80–90%) but resulted

in low conversion and virtually no selectivity for the

branched product (Table 1). It was decided, therefore,

to exclude these systems from further investigation.

Catalysts containing C₅H₈(PPh₂)₂or C₅H₈[P(OPh)₂]₂

ligands (Table 1; catalysts 1, 4, 7, and 3, 6, 9, respec-

tively) effected quantitative conversion of the substrate

within the reaction time chosen. In general, chemoselec-

tivities for the aldehydes, however, decreased substan-

tially (to ꢀ50% and below) on substituting these

bis(phosphane) and bis(phosphonite) complexes for the

[C₅H₈{P(N-pip)₂}₂Pt(Cl)(X)] catalyst precursors, except

for [C₅H₈(PPh₂)₂PtCl₂] (1), producing the two

propanals in 73% chemical yield and forming ethylben-

zene as the exclusive accompanying product. In con-

trast, use of alkyl(chloro) complexes 4 and 7 or of all

three bis(phosphonite)-containing compounds 3, 6, and

9 as pre-catalysts not only resulted in competitive hy-

drogenation of the styrene substrate but also induced

consecutive reduction of the initially produced isomeric

The bridging of two non-bonded platinum centers by

single m-X ligand to form discrete binuclear

a

molecules, as observed for 14, has little precedence,

except for a few [m-H{(R₃P)₂PtX}₂]⁺cations (R=Me,

Et; X=H, Ph, C₆F₅) similarly containing unsupported

PtꢀHꢀPt bridges [37] and some ‘A-frame’-like com-

pounds featuring additional bridging by bis(phos-

phanes) of the R₂PCH₂PR₂type, such as

[Pt₂{C(O)Me}₂(m-Cl)(m-dppm)₂]Cl [38]. In binuclear

cation 14⁺, the coordination planes of the two metals,

,

which are 4.1633(5) A apart, are twisted about the

bridging chloro ligand such that the angle between the

normals to the best l.s.q. planes spanned by the plat-

inum and the four donor atoms is 65.6°. Associated

torsion angles also deﬁning this ‘skewed’ conformation

are 71.7° for the C(31)ꢀPt(2)ꢀCl(1)ꢀPt(1) chain and

−111.2° for the P(4)ꢀPt(2)ꢀCl(1)ꢀPt(1) chain (Fig. 8).

In structurally characterized [m-H{(R₃P)₂PtX}₂]⁺com-

,

plexes, the Pt···Pt distances are close to 3.0 A, the two

coordination planes being nearly perpendicular to each

other [37]. The sharply distinct trans inﬂuences of the

methyl and m-Cl ligands are evident from the shrinkage

,

of the PtꢀP bonds facing the bridge (average 2.191 A)

as opposed to the stretching of the PtꢀP linkages oppo-

,

site CH₃(mean 2.319 A). Two nearly identical PtꢀCl

,

distances, 2.399(2) and 2.405(2) A, point to an essen-

tially symmetric PtꢀClꢀPt linkage, similar to the situa-

tion encountered for the more common double-bridged

Pt₂(m-X)₂

systems,

e.g.

[Pt₂(m-Cl)₂{Bu^t₂P(CH₂)₃-

PBu^t₂}₂]BF₄, where d(PtꢀCl)=2.4007(6) and 2.4051(7)

A [39]. While the angle at the bridging chloro ligand of

,

the latter complex is 102.67(1)°, the PtꢀClꢀPt angle in

the unsupported single bridge of 14⁺is increased to

120.2(1)°.

Table 1

[C₅H₈(PR₂)₂Pt(Cl)(X)]ꢀSnCl₂-catalyzed styrene hydroformylation: behavior of different platinum catalysts

[C₅H₈(PR₂)₂Pt(Cl)(X)] catalyst; R, X

Conversion (%)

Aldehydes (%)

b/n ratio

Ethylbenzene (%)

3-Phenylpropanol (%)

1; Ph, Cl

4; Ph, CH₃

7; Ph, CH₂CMe₃

100

73

47

50

68:32

94:6

91:9

27

32

–

21

18

5; N-pip, CH₃

8; N-pip, CH₂CMe₃

53

32

89

79

57:43

52:48

11

21

–

3; OPh, Cl

6; OPh, CH₃

9; OPh, CH₂CMe₃

100

34

53

50

91:9

65:35

75:25

36

35

ꢀ45

30

12

ꢀ5

0.012–0.013 mmol of Pt complex, 2 equiv. of SnCl₂, and 2.2 mmol of styrene in 3 ml of [D₈]toluene; T=80 °C; p(H₂)=p(CO)=40 bar; t=66

h. Entries in the tables represent the average values of, at least, duplicate runs. Percentages refer to the composition of the aldehyde–ethylbenzene–

3-phenylpropanol product mixtures; 2-phenylpropanol was also identiﬁed but could not be quantiﬁed by ¹H-NMR because of its low

concentration (55%).

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

227

Table 2

[C₅H₈{P(OPh)₂}₂PtCl₂]ꢀSnCl₂-catalyzed styrene hydroformylation: inﬂuence of reaction time

Reaction time (h)

Conversion (%)

Aldehydes (%)

b/n ratio

Ethylbenzene (%)

3-Phenylpropanol (%)

66

40

20

13

10

100

91

34

43

44

68

69

91:9

89:11

88:12

66:34

45:55

36

39

33

29

31

30

28

23

3

–

0.013 mmol of Pt complex, 0.021 mmol of SnCl₂, and 2.2 mmol of styrene in 3 ml of [D₈]toluene; T=80 °C; p(H₂)=p(CO)=40 bar (see also

legend to Table 1).

phenylpropanals to propanols (Scheme 1), complexes 6

and 9 being somewhat slower in this regard than 4 and

7 and, particularly, 3; see Table 1. The low chemoselec-

tivities to aldehydes achieved in these reactions there-

fore clearly originate from hydrogenation steps

occurring subsequently to hydroformylation. The con-

secutive formation of alcohols from primary hydro-

formylation products has rarely been observed [20d,40]

and was in fact unexpected, considering that SnCl₂-

modiﬁed [{bis(phosphane)}Pt] catalysts, unlike many

cobalt-containing catalysts [2c], in general, have little

propensity to promote the production of alcohols from

aldehydes. We are aware of only one further PtꢀSn

catalytic system, [{(S,S)-diop}Pt(C₂H₄)]ꢀSnCl₂(diop=

2,2 - dimethyl - 4,5 - bis(diphenylphosphanylmethyl) - 1,3-

dioxolane), where subsequent reduction of the isomeric

phenylpropanals (total yield at 100% conversion,

ꢀ85%) to the corresponding alcohols (ꢀ3%) occurred

in addition to competitive formation of ethylbenzene

(ꢀ12%) [25a]. It should be noted, however, that suc-

cessive hydrogenation of hydroformylation products

appears to be quite common for platinum complexes

activated by methanesulfonic acid or triﬂate additives

(see under Section 2.4).

With regard to the six [C₅H₈(PPh₂)₂Pt(Cl)(X)]ꢀSnCl₂

and [C₅H₈{P(OPh)₂}₂Pt(Cl)(X)]ꢀSnCl₂systems com-

piled in Table 1, good regioselectivities towards the

branched product (b/n]9:1) are seen for the two bis(-

phosphane)-supported catalysts 4 and 7 as well as for

dichloro complex 3 bearing a bis(phosphonite) ligand.

Conversely, b/n ratios of only 3:1 and below were

attained, if tin-modiﬁed dichloro derivative 1, possess-

ing the C₅H₈(PPh₂)₂chelate, or alkyl(chloro) complexes

6 and 9 with C₅H₈[P(OPh)₂]₂chelates were applied as

hydroformylation catalysts. With two of the catalytic

systems leading to enhanced regioselectivity at

quantitative substrate conversion, [C₅H₈{P(OPh)₂}₂-

PtCl₂]ꢀSnCl₂and [C₅H₈(PPh₂)₂Pt(Cl)(CH₃)]ꢀSnCl₂, sty-

rene hydroformylation in toluene as routine solvent was

also carried out at varied catalyst-to-substrate and CO/

H₂ratios as well as at different reaction temperatures

and times.

tained if the reaction was carried out in the presence of

[C₅H₈{P(OPh)₂}₂PtCl₂]ꢀSnCl₂for 10–66 h. The data

show that at 80 °C under 80 bar of CO/H₂(1:1), at a

catalyst-to-substrate ratio of 1:170, aldehyde produc-

tion predominates over ꢁCꢂCꢃ and ꢀCHꢂO hydro-

genation, if the reaction is stopped after 10–13 h. The

competitive hydrogenation product ethylbenzene is

formed in fairly constant portions of ca. 3595%, irre-

spective of the reaction time. Consecutive reduction of

the initially formed aldehydes to alcohols accounts for

the observation that in experiments reaching 100% sty-

rene conversion, the chemoselectivity to the hydro-

formylation products decreases with ongoing reaction

time. The regioisomeric excess in 2-phenylpropanal is

seen to increase from practically null at incomplete

transformation of the oleﬁn substrate to ꢀ9:1 after

complete consumption of the oleﬁn. As the reaction

progresses, this gain in regioselectivity roughly parallels

the growing production of 3-phenylpropanol. It is

therefore concluded that the high preferences for the

branched aldehyde displayed by [C₅H₈{P(OPh)₂}₂-

PtCl₂]ꢀSnCl₂(and also by tin-modiﬁed complexes 4 and

7; Table 1) in catalyses reaching quantitative transfor-

mation mirrors the successive hydrogenation reaction,

where the unbranched aldehyde is reduced faster to

3-phenylpropanol than the branched product to 2-

phenylpropanol. In fact, in all the product mixtures

investigated, the latter (though identiﬁable by NMR)

was present only at such low concentrations (B5%)

that could not be quantiﬁed accurately by spectroscopic

means. Similar behavior was previously reported for

[{(S,S)-diop}Pt(C₂H₄)]ꢀSnCl₂

and,

particularly,

affording the

[{(S,S)-diop}Pt(C₂H₄)]ꢀCH₃SO₃H,

propanol isomers with selectivities towards the linear

alcohol ranging from 68 to 97% [25a].

Data relevant to the effect of temperature on the

chemo- and regioselectivity of the [C₅H₈(PPh₂)₂Pt-

(Cl)(CH₃)]ꢀSnCl₂-catalyzed reaction are collected in

Table 3. Consistent with the results previously reported

by others [41,42], hydroformylation is highly favored

over competitive hydrogenation at low temperature

(40 °C) but disfavored at high temperature

(\100 °C), where the reaction is accompanied by the

formation of considerable amounts of unidentiﬁed side-

Table 2 summarizes the yields of the various hydro-

formylation and hydrogenation products that were ob-

228

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

Table 3

in p(CO) and decrease in p(H₂) is found to suppress the

unwanted competitive hydrogenation of the substrate,

thereby enhancing the selectivity to aldehydes. This

improvement in chemoselectivity, however, is accompa-

nied by a drastic decline of the selectivity for the

branched product, the b/n ratios falling from 96:4 and

94:6 for 1:2 and 1:1 CO/H₂gas mixtures to 80:20 at the

3:1 CO/H₂molar ratio and, eventually, to 66:34 for the

7:1 CO/H₂synthesis gas. Such trend in regioselectivity

differs from that reported for, e.g. [{(R)-(+)-bi-

nap}Pt(Cl)(X)]ꢀSnCl₂and [{(S)-(−)-MeO-biph}Pt(Cl)-

[C₅H₈(PPh₂)₂Pt(Cl)(CH₃)]ꢀSnCl₂-catalyzed styrene hydroformylation

at 100% conversion: inﬂuence of temperature

T (°C)

Aldehydes b/n ratio Ethylbenzene 3-Phenylpropanol

(%)

120 ^a25

96:4

93:7

94:6

84:16

50:50

47

33

32

34

26

28

27

21

18

–

100 40

80 47

60 48

40 74

0.013 mmol of Pt complex, 0.025 mmol of SnCl₂, and 2.2 mmol of

styrene in 3 ml of [D₈]toluene; p(H₂)=p(CO)=40 bar; t=66 h (see

also legend to Table 1).

(X)]ꢀSnCl₂

catalytic

systems

(MeO-biph=2,2%-

bis(diphenylphosphanyl)-6,6%-dimethoxy-1,1%-biphenyl;

X=Cl, CH₃), for which the 2-/3-phenylpropanal iso-

meric ratio remains almost unchanged on varying the

H₂and CO partial pressures [42], but resembles the

characteristics of the [{(R,R)-diop}PtCl₂]ꢀSnCl₂cata-

lyst, likewise displaying lower b/n selectivities at higher

CO/H₂ratios [3a]. Successive aldehyde hydrogenation

does not occur at high CO but low H₂partial pressures

(CO/H₂=7:1) and is also less important than competi-

tive styrene hydrogenation, if the partial pressure of H₂

is raised to 53 bar, p(CO) being simultaneously lowered

to 27 bar. This makes it difﬁcult to conclude about the

contribution of the consecutive reaction to the depen-

dence of the branched-to-normal selectivities on the

composition of the syn-gas mixture. Qualitatively, how-

ever, the lowest b/n regioselectivity is once more seen

under conditions where reduction of the aldehydes to

alcohols does not take place.

For the [C₅H₈{P(OPh)₂}₂PtCl₂]ꢀSnCl₂-catalyzed re-

action, the results summarized in Table 5 show the

effect of varied Pt complex-to-styrene molar ratios on

the aldehyde production and the branched-to-normal

selectivity as well as on the competitive and consecutive

formation of hydrogenated products. While the per-

centage of ethylbenzene in the ﬁnal product mixtures

(ꢀ3595%) reveals only little dependence on the plat-

inum-to-substrate ratio, the relative concentration of

3-phenylpropanol decreases from ]20% at the rela-

tively high catalyst-to-styrene molar ratio of 1:170 to

practically zero for the system containing the PtꢀSn

catalyst and the substrate in 1:1200 stoichiometry. Over

the same range, the total aldehyde yield is seen to

increase, the preference for the branched product (b/

^aConsiderable quantities of other side-products, presumably

oligomers, were formed as well.

products, probably resulting from styrene oligomeriza-

tion [20d]. There also exists the frequently observed [2b]

temperature range (60–100 °C) where the total alde-

hyde yield remains nearly unaffected. Consecutive re-

duction of the aldehydes to alcohols is not noticed at

40 °C but becomes more and more effective on raising

the temperature. Again, faster hydrogenation of the

unbranched aldehyde appears to contribute to the tem-

perature dependence of the b/n regioselectivity, which is

zero at 40 °C but increases sharply at higher tempera-

tures. The rise in regioselection for 2-phenylpropanal

which is seen on raising the reaction temperature is at

variance with the opposite temperature dependence of

the branched-to-normal selectivities found for several

other [{bis(phosphane)}PtCl₂]ꢀSnCl₂catalytic systems,

even though similar, albeit less distinct, behavior has

been described for [{(R)-(+)-binap}PtCl₂]ꢀSnCl₂and

[{(S,S)-diop}Pt(Cl)(CH₃)]ꢀSnCl₂catalysts [42b], where

binap=2,2%-bis(diphenylphosphanyl)-1,1%-binaphthyl.

The hydrogen and carbon monoxide partial pressures

can also considerably inﬂuence the activity and selectiv-

ity of hydroformylation catalysts [2b]. With

[C₅H₈(PPh₂)₂Pt(Cl)(CH₃)]ꢀSnCl₂as catalyst, both the

chemo- and the regioselectivity are affected to a great

extent by the CO and H₂partial pressures, as demon-

strated in Table 4 for a series of reactions performed

with different (1:2–7:1) CO–H₂mixtures at 80 bar total

pressure. As frequently observed for PtꢀSn-based hy-

droformylation catalysts [2b,3a,41a,42,43], an increase

Table 4

[C₅H₈(PPh₂)₂Pt(Cl)(CH₃)]ꢀSnCl₂-catalyzed styrene hydroformylation at 100% conversion: inﬂuence of CO and H₂partial pressures

p(CO) (bar)

p(H₂) (bar)

Aldehydes (%)

b/n ratio

Ethylbenzene (%)

3-Phenylpropanol (%)

27

40

60

70

53

40

20

10

17

47

61

88

96:4

94:6

80:20

66:34

65

32

23

12

18

21

16

–

0.013 mmol of Pt complex, 0.025 mmol of SnCl₂, and 2.2 mmol of styrene in 3 ml of [D₈]toluene; T=80 °C; t=66 h (see also legend to Table

1).

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

229

Table 5

[C₅H₈{P(OPh)₂}₂PtCl₂]ꢀSnCl₂-catalyzed hydroformylation of styrene at varied catalyst-to-substrate ratios

[Pt]-to-styrene molar ratio

Conversion (%)

Aldehydes (%)

b/n ratio

Ethylbenzene (%)

3-Phenylpropanol (%)

1:170

1:400

1:1200

100

44

55

61

88:12

83:17

56:44

33

31

39

23

14

–

0.013 mmol of Pt complex, 0.025 mmol of SnCl₂, and required amount of styrene in 3 ml of [D₈]toluene; T=80 °C; p(H₂)=p(CO)=40 bar;

t=20 h (see also legend to Table 1).

products [18f,20b], thus facilitating the initialization of

additional reaction channels and catalytic loops.

nꢀ9:1 at high platinum concentration), on the other

hand, being lost simultaneously (b/nꢀ1:1 at high sty-

rene concentration). This corroborates the interpreta-

tion that, for the systems under study, a preponderance

of the branched hydroformylation product in the ﬁnal

reaction mixtures hardly reﬂects any inherent regiose-

lectivity of the particular catalytic system but rather

mirrors the successive hydrogenation of the formyl

regioisomers, consuming 3-phenylpropanal in prefer-

ence to 2-phenylpropanal. Given that SnCl₂-modiﬁed

bis(phosphane)-coordinated platinum complexes nor-

mally behave as sluggish catalysts for hydrogenation

reactions immediately following the hydroformylation

step, the unexpected consecutive formation of alcohols

points to the formation of some unrecognized platinum

species being catalytically active for the reduction of the

formyl group [20d], which so far, however, could not be

revealed.

With regard to the generally accepted major steps of

catalytic cycles proposed for the PtꢀSn assisted hydro-

formylation process, the active species in the mecha-

nism initiated by complexes as different as [PtL₂Cl₂]

[44], [PtL₂(H)(X)] [18,19,45], [PtL₂(R)(X)] [17,18d,19],

or [PtL₂{C(O)R}(X)] [18a,18b,18e] (L=phosphane;

X=Cl, SnCl₃; R=alkyl, aryl) is thought to be

[Pt(CO)(L)(H)(SnCl₃)]. Similarly, the PtꢀSnCl₃-bonded

complexes [{Ph₂P(CH₂)_nPPh₂}Pt(H)(SnCl₃)], [{Ph₂P-

(CH₂)_nPPh₂}Pt(C₂H₅)(SnCl₃)], and [{Ph₂P(CH₂)_nPPh₂}-

Pt{C(O)C₂H₅}(SnCl₃)] (n=3, 4) were proposed as com-

mon key-intermediates involved in the hydroformyla-

tion of ethylene catalyzed by either [{Ph₂P(CH₂)_nPPh₂}-

PtCl₂]ꢀSnCl₂or [{Ph₂P(CH₂)_nPPh₂}Pt(C₂H₅)(SnCl₃)]

[18f]. On the other hand, more recent studies of the

In order to gain an insight into the products originat-

ing from selected [C₅H₈(PR₂)₂Pt(Cl)(alkyl)] catalyst pre-

cursors upon combination with tin(II) chloride,

complex 4, [C₅H₈(PPh₂)₂Pt(Cl)(CH₃)], was allowed to

interact with SnCl₂in 1:1 stoichiometry in acetone at

room temperature. Though the starting material was

smoothly consumed within 10 min, no pure

trichlorostannato product [C₅H₈(PPh₂)₂Pt(CH₃)(SnCl₃)]

(15) was obtained, a roughly 5:2:3 mixture of 15,

[C₅H₈(PPh₂)₂Pt(Cl)(SnCl₃)] (16), and [C₅H₈(PPh₂)₂-

PtCl₂] (1) being formed instead. Analogous treatment

of [C₅H₈{P(OPh)₂}₂Pt(Cl)(CH₃)] (6) with SnCl₂in ace-

tone

similarly

caused

the

production

of

[C₅H₈{P(OPh)₂}₂Pt(CH₃)(SnCl₃)]

(17), [C₅H₈-

{P(OPh)₂}₂Pt(Cl)(SnCl₃)] (18), and [C₅H₈{P(OPh)₂}₂-

PtCl₂] (3) in comparable molar ratio. Only if the reac-

tants were combined at low temperature (−20 °C),

tin(II) chloride was observed to cleanly insert into 6,

giving 17 as the almost exclusive complex, which at

room temperature, however, underwent ready degrada-

tion to afford 18 and 3 as accompanying products.

When the reaction between equimolar amounts of

SnCl₂and either 4 or 6 was carried out in toluene at

80 °C for 16–72 h, i.e. apart from the absence of

syn-gas pressure under conditions typically applied dur-

ing hydroformylation, the product mixtures were domi-

nated by dichloro and bis(trichlorostannato) complexes,

[C₅H₈(PPh₂)₂PtX₂] [X=Cl (1), SnCl₃(19)] and

[C₅H₈{P(OPh)₂}₂PtX₂] [X=Cl (3), SnCl₃(20)], the cor-

responding mono-trichlorostannates 15/16 and 17/18

representing only minor constituents of the resulting

product mixtures. When these reactions were run under

80 bar of synthesis gas, ³¹P- and ¹H-NMR spectra

taken immediately after depressurization indicated the

presence of [C₅H₈(PR₂)₂PtCl₂] together with acetalde-

hyde [l(CHO)=9.18 (q, J=2.9 Hz)]. No binuclear

[{m-C₅H₈(PR₂)₂}{Pt(H)(R₂P)₂C₅H₈}₂]²⁺, analogous to

the diop- or bddp-containing diplatinum cations [(m-

PSP){Pt(H)(PSP)}₂]²⁺that were previously observed

[{(S,S)-bdpp}Pt(Cl)(CH₃)]ꢀSnCl₂

catalytic

system

have

(bdpp=2,4-bis(diphenylphosphanyl)pentane)

shown that the presence of intermediates containing

PtꢀSnCl₃bonds is indispensable only for the early

stages of the catalytic cycle and that both carbonylation

and aldehyde formation occur in four-coordinate

cations possessing SnCl⁻₃counter-ions [20a,20b]. Fur-

thermore, there are clear indications that alkyl

trichlorostannato

complexes

resulting

from

in

CO/H₂-pressurized

solutions

of

[{(S,S)-

[{bis(phosphane)}Pt(Cl)(alkyl)] precursors and SnCl₂in

the ﬁrst step can easily decompose to form

[{bis(phosphane)}PtCl₂] together with unknown tin

bdpp}Pt(CH₃)(SnCl₃)] [20b] or Pt/2e⁻ꢀ[(diop)PtCl₂]ꢀSn/

Sn²⁺electrocatalysts [24], was however detected.

230

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

From the reactions studied, it is possible to propose

chloro(methyl) complexes 4 and 6 in the presence of

added tin(II) chloride. A conceivable sequence of reac-

tion steps could involve CꢀSn reductive elimination

from the initially formed insertion products

[C₅H₈(PR₂)₂Pt(CH₃)(SnCl₃)] (15, 17). Analogous CꢀSi

and CꢀGe elimination from [(Me₂PhP)₂Pt(CH₃)(EPh₃)]

(E=Si, Ge) has been described recently [46]. The 14e

fragments [C₅H₈(PR₂)₂Pt(0)] so generated can be ex-

pected to readily interact with eliminated CH₃SnCl₃

molecules, forming [C₅H₈(PR₂)₂PtCl₂] which, in turn,

will produce [C₅H₈(PR₂)₂Pt(Cl)(SnCl₃)] (16, 18) and

[C₅H₈(PR₂)₂Pt(SnCl₃)₂] (19, 20) by (possibly reversible)

SnCl₂insertion (Scheme 2). The fate of the tin-contain-

ing residue, formally CH₃SnCl, could not be clariﬁed

unequivocally. Traces of light grey precipitates that

might be elemental tin were observed occasionally. On

the other hand, singlets ﬂanked by tin satellites [l=

0.68, 0.73; J(^117,119Sn,H)=42 Hz], indicative of the

presence of CH₃Sn groups in solution [47], were seen in

two alternate (and perhaps competing) pathways on

which the methyl group is removed from the

[C₅H₈(PR₂)₂Pt(Cl)(CH₃)]ꢀSnCl₂systems during cataly-

sis: (i) hydrogenolytic elimination of CH₃CHO from a

platinum acetyl intermediate, possibly (though not nec-

essarily) [C₅H₈(PR₂)₂Pt(CO){C(O)CH₃}]SnCl₃as an

analogue of the bdpp-coordinated [{(S,S)-bdpp}Pt-

(CO){C(O)CH₃}]SnCl₃previously characterized by in

situ high-pressure NMR spectroscopy [20a,20b]; (ii)

SnCl₂-assisted conversion of [C₅H₈(PR₂)₂Pt(Cl)(CH₃)]

into [C₅H₈(PR₂)₂Pt(X)(Y)] (X, Y=Cl, SnCl₃). Al-

though the details of the latter transformation are

unclear, it must be completely different from that previ-

ously postulated by Kolla´r and colleagues for the for-

mation of [{(S,S)-bdpp}PtCl₂] from [{(S,S)-bdpp}Pt-

{CH(CH₃)CO₂Et}(SnCl₃)], where b-elimination of

CH₂ꢂCHCO₂Et

initially

generates

[{(S,S)-

bdpp}Pt(H)(SnCl₃)] which then is believed to undergo

reductive elimination of HSnCl₃, followed by reaction

of the resulting platinum(0) carbenoid with CHCl₃sol-

vent molecules [20b]. In earlier work by Scrivanti et al.

[18f], the rapid decomposition of [{Ph₂P(CH₂)_nPPh₂}-

Pt(C₂H₅)(SnCl₃)] to [{Ph₂P(CH₂)_nPPh₂}PtCl₂] (n=3, 4)

occurring in solution in the absence of added ethylene

was similarly accounted for by reductive elimination of

HSnCl₃from [{Ph₂P(CH₂)_nPPh₂}Pt(H)(SnCl₃)] to pro-

duce [{Ph₂P(CH₂)_nPPh₂}Pt(0)] as a reactive intermedi-

ate, which in turn was suggested to yield the ﬁnal

dichloride along with an unknown tin-containing by-

product by extraction of chlorine from SnꢀCl bonds.

Since b-elimination with formation of a transient hy-

dride species cannot be operative for the degradation of

methylplatinum complexes, an alternative mechanism

has to be considered for the rapid transformation of

1

the H-NMR spectra of samples resulting from thermal

treatment of [C₅H₈(PPh₂)₂Pt(Cl)(CH₃)] (4) with SnCl₂

in toluene.

The above observations with [C₅H₈(PR₂)₂Pt-

(Cl)(CH₃)]ꢀSnCl₂lend further credence to the view that

the catalytic results collected in Tables 1–5 are, at best,

loosely associated with intrinsic ligand and complex

properties of the respective catalysts but rather express

the involvement in the catalytic cycle of several unre-

vealed species being active competitively.

As there exists only a single PtꢀSnCl₃complex con-

taining a chelating bis(phosphane) ligand for which

crystallographic information is available from the liter-

ature, viz. [{(S,S)-bdpp}Pt(I)(SnCl₃)] [20c], the crystal

structure of one of the trichlorostannato derivatives

described before, [C₅H₈(PPh₂)₂Pt(Cl)(SnCl₃)] (16), was

determined. The structure consists of two independent

molecules in the asymmetric unit, one of which pos-

sesses a rotationally disordered SnCl₃ligand (Fig. 9).

The coordination around the central metal is close to

square planar, the PtP₂planes being rotated with re-

spect to those deﬁned by Pt, Sn, and Cl at angles of

1.9° in molecule 2 and 5.4° in molecule 1. The PtꢀSn

bond length averaged over the two crystallographically

[C₅H₈(PR₂)₂Pt(Cl)(CH₃)]

trichlorostannato), and bis(trichlorostannato) products

[C₅H₈(PR₂)₂Pt(X)(Y)], which takes place for

to

dichloro,

chloro(-

,

independent molecules of structure 16, 2.567 A, is

shorter than the PtꢀSn distances measured for [{(S,S)-

,

bdpp}Pt(I)(SnCl₃)] (2.614 A) [20c] and related

[(R₃P)₂Pt(X)(SnCl₃)] complexes (R=Ph, Cy; X=H,

,

Cl; PtꢀSn, 2.590–2.601 A) [19,48,49], but absolutely

,

matches the range down to 2.478 A observed for cova-

lent PtꢀSnCl₃interactions [50]. Because of the substan-

tial trans inﬂuence of the SnCl₃ligand, the PtꢀP bonds

opposite PtꢀSn should be signiﬁcantly longer than

those opposite the metal-to-halogen bond. Rather un-

expectedly, such bond-lengthening is, however, not ap-

,

parent for complex 16 (mean d(PtꢀP), 2.282 A trans to

Scheme 2. Pathway proposed for the degradation of alkyl(-

trichlorostannato) complexes in solution.

,

SnCl₃and 2.280 A trans to Cl), as opposed to [{(S,S)-

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

231

substituents in the PPh₂groups cis to chloride, whereas

large differences in the axial–equatorial character are

evident for the phenyl rings in the PPh₂groups cis to

the bulky SnCl₃ligands: PꢀPtꢀPꢀC_ipsotorsion angles,

98–99° for the more axial and (with opposite sign)

135–136° for the more equatorial alignment.

bdpp}Pt(I)(SnCl₃)], where the PtꢀP distances amount to

−

,

2.300 A with SnCl₃as trans-bonded group but are

,

shortened to 2.250 A with iodide as trans ligand [20c].

We assume that the PtꢀP bonds trans to PtꢀCl and,

hence, cis to PtꢀSnCl₃in structure 16 are slightly elon-

gated owing to steric repulsion between the PPh₂and

SnCl₃groups in question. For molecule 1 (showing no

SnCl₃disorder), such hindrance is apparent from the

PtꢀSnꢀCl angles which increase from 117.5(2)° for

Pt(1)ꢀSn(1)ꢀCl(2) to 120.2(2) and 123.1(2)° for

Pt(1)ꢀSn(1)ꢀCl(3) and Pt(1)ꢀSn(1)ꢀCl(4), the joined

ClꢀSnꢀCl angles decreasing from 101.1(3)° for

Cl(3)ꢀSn(1)ꢀCl(4) to 96.7(4)° and 93.3(3)° for

Cl(2)ꢀSn(1)ꢀCl(3) and Cl(2)ꢀSn(1)ꢀCl(4), respectively.

As observed for neopentyl complexes 7–9 and 13, the

PꢀPtꢀPꢀC_ipsotorsion angles (109–112° and, with oppo-

site sign, 126–127°) indicate little axial–equatorial dif-

ferentiation for the orientation of the phenyl

2.3. Styrene hydroformylation with optically acti6e

[C₅H₈(PR₂)₂Pt(Cl)(X)] catalysts

Treatment of the substitutionally labile cyclooctadi-

ene precursors [(1,5-C₈H₁₂)Pt(Cl)(X)] (X=Cl, CH₃,

CH₂CMe₃) with equimolar quantities of the

C₅H₈(PR₂)₂ligands as resolved (−)-(1R,2R)-/(+)-

(1S,2S)-C₅H₈[P(OPh)₂]₂

and

(+)-(1R,2R)-/(−)-

(1S,2S)-C₅H₈(PPh₂)₂enantiomers (see Section 4)

allowed complexes 3, 4, and 7 to be prepared as opti-

cally

active

derivatives,

viz.

(+)-[(1R,2R)-

C₅H₈{P(OPh)₂}₂PtCl₂] [(R,R)-3], (−)-[(1S,2S)-C₅H₈-

{P(OPh)₂}₂PtCl₂] [(S,S)-3], (−)-[(1R,2R)-C₅H₈(PPh₂)-

Pt(Cl)(X)], and (+)-[(1S,2S)-C₅H₈(PPh₂)Pt(Cl)(X)],

where X=CH₃[(R,R)-4, (S,S)-4] and CH₂CMe₃

[(R,R)-7, (S,S)-7], respectively. Of these, the enan-

tiomers (R,R)-3 and (S,S)-3 were isolated as monoclinic

single crystals (space group P2₁) and fully characterized

by X-ray analysis. A number of the bond lengths and

angles given in the legends to Figs. 10 and 11 deviate

Fig. 9. Molecular structures of the two crystallographically indepen-

dent molecules of [C₅H₈(PPh₂)₂Pt(Cl)(SnCl₃)] (16) showing the three-

fold rotational disorder of the SnCl₃ligand in molecule 2. Selected

,

bond lengths (A) and valence and torsion angles (°) for molecule 1:

Pt(1)ꢀSn(1), 2.572(2); Pt(1)ꢀCl(1), 2.283(9); Pt(1)ꢀP(1), 2.281(5);

Pt(1)ꢀP(2), 2.275(5); Sn(1)ꢀCl(2), 2.363(7); Sn(1)ꢀCl(3), 2.326(8);

Sn(1)ꢀCl(4), 2.359(6). Sn(1)ꢀPt(1)ꢀCl(1), 85.2(3); Sn(1)ꢀPt(1)ꢀP(1),

173.5(1); Sn(1)ꢀPt(1)ꢀP(2), 97.3(1); Cl(1)ꢀPt(1)ꢀP(1), 90.6(3);

Cl(1)ꢀPt(1)ꢀP(2),

176.9(3);

P(1)ꢀPt(1)ꢀP(2),

87.0(2);

Pt(1)ꢀ

Sn(1)ꢀCl(2), 117.5(2); Pt(1)ꢀSn(1)ꢀCl(3), 120.2(2); Pt(1)ꢀSn(1)ꢀCl(4),

123.1(2); Cl(2)ꢀSn(1)ꢀCl(3), 96.7(4); Cl(2)ꢀSn(1)ꢀCl(4), 93.3(3);

Cl(3)ꢀSn(1)ꢀCl(4), 100.1(3). P(1)ꢀPt(1)ꢀP(2)ꢀC(18), −136.0(8);

P(1)ꢀPt(1)ꢀP(2)ꢀC(24), 99.5(8); P(2)ꢀPt(1)ꢀP(1)ꢀC(6), −126.7(8);

,

P(2)ꢀPt(1)ꢀP(1)ꢀC(12), 109.6(7). — Selected bond lengths (A) and

valence and torsion angles (°) for molecule 2: Pt(2)ꢀSn(2), 2.562(2);

Pt(2)ꢀCl(5), 2.289(9); Pt(2)ꢀP(3), 2.283(6); Pt(2)ꢀP(4), 2.286(5);

Sn(2)ꢀCl(6), 2.40(2); Sn(2)ꢀCl(7), 2.35(3); Sn(2)ꢀCl(8), 2.36(2);

Sn(2)ꢀCl(6a), 2.56(4); Sn(2)ꢀCl(7a), 2.43(4); Sn(2)ꢀCl(8a), 2.33(3);

Sn(2)ꢀCl(6b), 2.45(3); Sn(2)ꢀCl(7b), 2.30(3); Sn(2)ꢀCl(8b), 2.27(4).

Sn(2)ꢀPt(2)ꢀCl(5),

85.0(3);

Sn(2)ꢀPt(2)ꢀP(3),

175.8(1);

Sn(2)ꢀPt(2)ꢀP(4), 97.2(1); Cl(5)ꢀPt(2)ꢀP(3), 90.9(3); Cl(5)ꢀPt(2)ꢀP(4),

177.2(3); P(3)ꢀPt(2)ꢀP(4), 86.9(2); Pt(2)ꢀSn(2)ꢀCl(6), 114.9(5);

Pt(2)ꢀSn(2)ꢀCl(7), 118.8(9); Pt(2)ꢀSn(2)ꢀCl(8), 122.3(8); Pt(2)ꢀ

Sn(2)ꢀCl(6a), 117(1); Pt(2)ꢀSn(2)ꢀCl(7a), 118(1); Pt(2)ꢀSn(2)ꢀCl(8a),

126(1); Pt(2)ꢀSn(2)ꢀCl(6b), 116.1(9); Pt(2)ꢀSn(2)ꢀCl(7b), 118.8(7);

Pt(2)ꢀSn(2)ꢀCl(8b), 122.2(9); Cl(6)ꢀSn(2)ꢀCl(7), 93(1); Cl(6)ꢀ

Sn(2)ꢀCl(8), 101(1); Cl(7)ꢀSn(2)ꢀCl(8), 101(1); Cl(6a)ꢀSn(2)ꢀCl(7a),

92(2); Cl(6a)ꢀSn(2)ꢀCl(8a), 93(2); Cl(7a)ꢀSn(2)ꢀCl(8a), 98(2);

Cl(6b)ꢀSn(2)ꢀCl(7b),

Cl(7b)ꢀSn(2)ꢀCl(8b),

91(1);

106(2).

Cl(6b)ꢀSn(2)ꢀCl(8b),

P(3)ꢀPt(2)ꢀP(4)ꢀC(47),

97(1);

135.2(9);

P(3)ꢀPt(2)ꢀP(4)ꢀC(53), −98.0(8); P(4)ꢀPt(2)ꢀP(3)ꢀC(35), 126.0(9);

P(4)ꢀPt(2)ꢀP(3)ꢀC(41), −111.9(8).

Fig. 9.

232

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

to −138.4(5) and −139.8(5)° in the two independent

molecules of (R,R)-3 and, respectively, to 138.3(5) and

140.3(5)° for (S,S)-3, the corresponding torsion angles

for the axially oriented groups being 99.1(4)°/97.1(4)°

for the R,R enantiomer and −98.6(4)°/−97.0(4)° for

the S,S form. While the orientation of the phenyl rings

in the equatorial phenoxy substituents, relative to the

PtCl₂fragments of the molecules, can be described as

‘face-on’, the phenyl rings in the axially aligned phen-

oxy groups and the plane spanned by the metal and the

chloro ligands are inclined to each other in a more

parallel fashion such that these phenyl substituents

appear to ‘roof in’ part of the coordination plane. Less

pronounced differentiation between an axial or equato-

rial disposition is evident for the remaining two phen-

oxy groups, where the PꢀPtꢀPꢀO torsion angles vary

between 110.0(4)°/113.6(4)° and

−132.4(4)°/−

Fig. 10. Molecular structure of one of the two crystallographically

independent molecules of [(R,R)-C₅H₈{P(OPh)₂}₂PtCl₂], (R,R)-3. Se-

129.4(4)° in structure (R,R)-3 and −109.7(5)°/−

113.2(5)° and 132.5(5)°/130.4(4)° in complex (S,S)-3.

These substituents are seen to contain their phenyl rings

‘edge-on’-oriented in direction of, and away from, the

PtCl₂moieties.

To probe the above complexes for their enantioselec-

tivity in the asymmetric hydroformylation of styrene,

compounds (R,R)-3, (S,S)-3, and (S,S)-4 were com-

bined with SnCl₂and the oleﬁn in toluene under the

,

lected bond lengths (A) and valence and torsion angles (°):

Pt(1)ꢀCl(1), 2.358(3); Pt(1)ꢀCl(2), 2.327(3); Pt(1)ꢀP(1), 2.194(3);

Pt(1)ꢀP(2), 2.204(3). Cl(1)ꢀPt(1)ꢀCl(2), 89.8(1); Cl(1)ꢀPt(1)ꢀP(1),

178.4(1); Cl(1)ꢀPt(1)ꢀP(2), 92.2(1); Cl(2)ꢀPt(1)ꢀP(1), 91.6(1);

Cl(2)ꢀPt(1)ꢀP(2),

176.6(2);

P(1)ꢀPt(1)ꢀP(2),

86.4(1).

P(1)ꢀPt(1)ꢀP(2)ꢀO(3), −129.4(4); P(1)ꢀPt(1)ꢀP(2)ꢀO(4), 113.6(4);

P(2)ꢀPt(1)ꢀP(1)ꢀO(1), 97.1(4); P(2)ꢀPt(1)ꢀP(1)ꢀO(2), −139.8(5). —

Corresponding distances and angles for molecule 2: Pt(2)ꢀCl(3),

2.333(3); Pt(2)ꢀCl(4), 2.365(3); Pt(2)ꢀP(3), 2.200(3); Pt(2)ꢀP(4),

2.199(3). Cl(3)ꢀPt(2)ꢀCl(4), 90.0(1); Cl(3)ꢀPt(2)ꢀP(3), 176.3(2);

Cl(3)ꢀPt(2)ꢀP(4), 91.6(1); Cl(4)ꢀPt(2)ꢀP(3), 92.4(1); Cl(4)ꢀPt(2)ꢀP(4),

178.4(1); P(3)ꢀPt(2)ꢀP(4), 86.1(1). P(3)ꢀPt(2)ꢀP(4)ꢀO(7), −138.4(5);

P(3)ꢀPt(2)ꢀP(4)ꢀO(8), 99.1(4); P(4)ꢀPt(2)ꢀP(3)ꢀO(5), −132.4(4);

P(4)ꢀPt(2)ꢀP(3)ꢀO(6), 110.0(4).

signiﬁcantly from the corresponding structural parame-

ters that were previously derived from an X-ray struc-

ture determination of a racemic crystal of 3 (monoclinic

P2₁/n) [13d]. This is particularly obvious for the PtꢀCl

bonds, which in either crystallographically-independent

molecule of the two (R,R)-3 and (S,S)-3 enantiomers

,

differ by 0.030 A (2.325(3)–2.331(3) vs. 2.358(3)–

,

2.365(3) A) but are averaged to 2.346(2) A in structure

3 made up of equal proportions of the mirror image

isomers. Averaging of structural parameters on going

from either (R,R)-3 or (S,S)-3 to racemic 3 is, inter

alia, also evident from the trans PꢀPtꢀCl angles which

are different in the two enantiomorphous crystals

(176.1(2)–176.6(2) vs. 178.2(1)–178.4(1)°) but are bal-

anced out to 177.60(8)° in the centrosymmetric struc-

ture of the racemic specimen [13d]. The perspective

views of the structural models given in Figs. 10 and 11

identify the puckering of the chelate rings in the u,l

notation as u for the R,R- and l for the S,S-conﬁgured

enantiomer. In either isomer the two phenoxy sub-

stituents belonging to the P(OPh)₂groups cis to the

shorter PtꢀCl bond exhibit distinct differences in the

axial–equatorial character of their orientation relative

to the coordination plane. Thus, the PꢀPtꢀPꢀO torsion

angles for the equatorially-aligned substituents amount

Fig. 11. Molecular structure of one of the two crystallographically

independent molecules of [(S,S)-C₅H₈{P(OPh)₂}₂PtCl₂], (S,S)-3. Se-

,

lected bond lengths (A) and valence and torsion angles (°):

Pt(1)ꢀCl(1), 2.360(3); Pt(1)ꢀCl(2), 2.325(3); Pt(1)ꢀP(1), 2.207(3);

Pt(1)ꢀP(2), 2.205(3). Cl(1)ꢀPt(1)ꢀCl(2), 89.6(1); Cl(1)ꢀPt(1)ꢀP(1),

178.2(1); Cl(1)ꢀPt(1)ꢀP(2), 92.3(1); Cl(2)ꢀPt(1)ꢀP(1), 92.0(1);

Cl(2)ꢀPt(1)ꢀP(2),

176.1(1);

P(1)ꢀPt(1)ꢀP(2),

86.1(1).

P(1)ꢀPt(1)ꢀP(2)ꢀO(3), 130.4(5); P(1)ꢀPt(1)ꢀP(2)ꢀO(4), −113.2(5);

P(2)ꢀPt(1)ꢀP(1)ꢀO(1), −97.0(4); P(2)ꢀPt(1)ꢀP(1)ꢀO(2), 140.3(5). —

Corresponding distances and angles for molecule 2: Pt(2)ꢀCl(3),

2.331(3); Pt(2)ꢀCl(4), 2.362(3); Pt(2)ꢀP(3), 2.200(3); Pt(2)ꢀP(4),

2.196(4). Cl(3)ꢀPt(2)ꢀCl(4), 90.3(1); Cl(3)ꢀPt(2)ꢀP(3), 176.2(2);

Cl(3)ꢀPt(2)ꢀP(4), 91.3(1); Cl(4)ꢀPt(2)ꢀP(3), 92.1(1); Cl(4)ꢀPt(2)ꢀP(4),

178.4(1); P(3)ꢀPt(2)ꢀP(4), 86.4(1). P(3)ꢀPt(2)ꢀP(4)ꢀO(7), 138.3(5);

P(3)ꢀPt(2)ꢀP(4)ꢀO(8), −98.6(4); P(4)ꢀPt(2)ꢀP(3)ꢀO(5), 132.5(5);

P(4)ꢀPt(2)ꢀP(3)ꢀO(6), −109.7(5).

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

233

Table 6

Asymmetric styrene hydroformylation catalyzed by complexes (R,R)-3, (S,S)-3, and (S,S)-4

T (°C)

p(CO) (bar)

p(H₂) (bar)

Time (h)

Conversion (%)

Aldehydes (%)

b/n ratio

e.e. (%)

(conﬁguration)

Ethylbenzene

(%)

(R,R)-3

80

40

13

100

69

64:36

0.7 (S)

28 ^a

(S,S)-3

40

60

40

13

100

79

72

68

53:47

66:34

0.7 (S)

0.6 (R)

21

28

80

29 ^a

(S,S)-4

80

20

40

60

40

24

100

70

75

65:35

67:33

9.1 (R)

17.7 (R)

30

25

0.013 mmol of Pt complex, 0.025 mmol of SnCl₂, and 2.2 mmol of styrene in 3 ml of [D₈]toluene.

^aApproximately 3% of 3-phenylpropanol was also detected.

usual conditions (Pt complex–SnCl₂–substrate=

1:2:170; T=80 °C; p(H₂)=p(CO)=40 bar). Accept-

ing inevitably low regioisomeric excesses of the

branched aldehyde, the reaction mixtures were depres-

surized after 13–24 h in order to suppress the consecu-

tive hydrogenation of the primary hydroformylation

products. With the phenoxy-substituted systems (R,R)-

3 and (S,S)-3 as catalyst precursors, practically null

enantiomeric excesses were found, even if the tempera-

ture was decreased to 40 °C (Table 6). While this could

be explained by an only limited rigidity of the

C₅H₈[P(OPh)₂]₂ligand bearing phenoxy substituents

which can swivel about the PꢀOꢀC-hinges, use of the

much more rigid PꢀC-bonded chelate phosphane

C₅H₈(PPh₂)₂as steering ligand in the (S,S)-4/SnCl₂

catalyst also resulted in discouraging low enantioselec-

tivities of, at best, 18%. Hence, intrinsic ligand proper-

ties (in this case, any well or less well deﬁned spatial

orientation of the donor groups) once more do not

seem to contribute to a signiﬁcant extent to the cata-

lytic outcome of the [C₅H₈(PR₂)₂Pt(X)(Y)]-catalyzed

hydroformylation of styrene. The low optical yields

obtained with platinum complexes of the respective

C₅H₈[P(OPh)₂]₂and C₅H₈(PPh₂)₂enantiomers most

probably also reﬂect the presence of different catalytic

intermediates and cannot be attributed only to exten-

sive racemization of the branched aldehyde as a conse-

quence of reaction time and temperature, because

racemization should be slow at 40–60 °C [20d].

branched product was virtually worthless owing to the

predominance of the normal aldehyde in the mixture

(Table 7).

Adding two equivalents of tin(II) chloride to

[C₅H₈(PPh₂)₂Pt(CH₃)(OSO₂CF₃)] caused the perfor-

mance of the catalytic system to change dramatically.

Using a catalyst-to-substrate ratio of 1:170 and similar

conditions as before, quantitative conversion of the

styrene substrate was observed within 20–40 h. Due to

extensive subsequent hydrogenation of the primary hy-

droformylation products, the total aldehyde yield of the

reaction was, however, much lower than that given by

the tin-free catalyst. Both in the aldehydes and in the

alcohols, the selectivities for the branched products

were relatively high but, concerning the propanals,

inverse to those provided by tin-free 11 and, with

regard to the propanols, inverse to those provided by

platinum–tin catalysts derived from chloro-substituted

complexes such as 3 and 4.

With triﬂate complex 11 as catalyst precursor, the

consecutive hydrogenation of the two isomeric alde-

hydes did not come unexpected, since previous work

had shown that successive hydrogenation of the alde-

hyde

regioisomers

is

also

a

feature

of

[{bis(phosphane)}PtCl₂]ꢀSn(O₃SCF₃)₂ꢀSnCl₂catalysts

[20d] and [{bis(phosphane)}Pt(C₂H₄)] complexes acti-

vated by methanesulfonic acid [25a]. The distinct selec-

tivity

of

[C₅H₈(PPh₂)₂Pt(CH₃)(OSO₂CF₃)]ꢀSnCl₂

towards the formation of 2-phenylpropanol differs,

however, from that reported for these earlier systems,

which were shown to favor the production of the linear

alcohol over that of the branched.

2.4. Styrene hydroformylation using a

[C₅H₈(PPh₂)₂Pt(CH₃)(OSO₂CF₃)]ꢀSnCl₂catalyst

In the absence of added SnCl₂, triﬂate complex 11

showed little hydroformylation activity. Thus, at a plat-

inum-to-oleﬁn ratio of 1:85, less than 20% styrene

conversion was effected in toluene at 80 °C under

50–80 bar of CO/H₂(1:1) after 66 h. Although the

chemoselectivity towards aldehydes was good (ꢀ90%)

at these low conversions, the regioselectivity for the

3. Conclusions

This work has shown that platinum complexes con-

taining cyclopentane-based C₂chiral bis(phosphane)

and bis(phosphonite) ligands, [C₅H₈(PPh₂)₂Pt(Cl)(X)]

(X=CH₃, CH₂CMe₃), [C₅H₈{P(OPh)₂}₂PtCl₂], and

Table 7

[C₅H₈(PPh₂)₂Pt(CH₃)(OSO₂CF₃)]-catalyzed styrene hydroformylation in the absence and presence of added tin(II) chloride

/

T (°C)

p (bar)

Time (h)

Conversion (%)

Total aldehyde yield Selectivity for

Total alcohol yield

(%)

Selectivity for 2-phenylpropanol Ethylbenzene yield

(%)

2-phenylpropanal

No SnCl₂added (complex–styrene=1:85)

80

50

80

66

10

17

ꢀ90

ꢀ20:80

ꢀ10

2 equiv. of SnCl₂added (complex–styrene=1:170)

a

80

36

20

100

6

49

75

32

77:23

75:25

19

94:6

0.013 mmol of Pt complex 11 and required amount of styrene in 3 ml of [D₈]toluene; p(H₂)=p(CO).

^aNot determined; practically no n-aldehyde detected by NMR.

630

(

2

243

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

235

[C₅H₈(PPh₂)₂Pt(CH₃)(OSO₂CF₃)] are catalysts for the

hydroformylation of styrene, if activated by SnCl₂. To

our best knowledge, no application of bis(phospho-

nite)-containing transition metal complexes to the hy-

droformylation of prochiral substrates has ever been

described before. The chemoselectivity to the formation

of aldehydes at 100% conversion is, in general, rela-

tively low because hydroformylation is always followed

by hydrogenation of the initially produced propanals to

the corresponding alcohols. With [C₅H₈(PPh₂)₂Pt-

(Cl)(alkyl)]ꢀSnCl₂(alkyl=CH₃, CH₂CMe₃) and

[C₅H₈{P(OPh)₂}₂PtCl₂]ꢀSnCl₂as catalytic systems, the

unbranched aldehyde undergoes consecutive reduction

faster than the branched product, which accounts for

the high regioselectivity towards the branched aldehyde

(b/n ratios]91:9) that is observed at complete conver-

sion of the styrene substrate. Irrespective of a rigid or

less rigid substitution of the donor functions of the

C₅H₈(PR₂)₂ligands, only low enantiomeric excesses

were found for selected catalysts bearing optically ac-

tive C₅H₈[P(OPh)₂]₂or C₅H₈(PPh₂)₂chelate phos-

phanes. In view of the different catalytically active

species probably involved in the competitive and con-

secutive hydroformylation and hydrogenation reactions

that were observed for the systems studied, it seems

unlikely that further modiﬁcation of the cyclopentane-

based supporting ligands of [C₅H₈(PR₂)₂Pt(X)(Y)] com-

plexes will give rise to signiﬁcantly enhanced

selectivities.

PR₂=PPh₂, P(N-pip)₂, or P(OPh)₂, were prepared as

previously described [12,13d]. Similar procedures were

used for the synthesis of the enantiopure compounds

(1R,2R)- and (1S,2S)-C₅H₈(PR₂)₂(R=Ph, OPh) from

the resolved enantiomers of trans-C₅H₈(PCl₂)₂

[13a,13c,13e]. As expected, the products exhibited

NMR and MS data corresponding in all respects to

those reported for the racemates. — Optical rotations

(all c=1, CHCl₃): (1R,2R)-C₅H₈(PPh₂)₂; [h]₅₈₉+173,

[h]₅₇₈+182, [h]₅₄₆+210, [h]₄₃₆+398, [h]₃₆₅+728.

(1S,2S)-C₅H₈(PPh₂)₂; [h]₅₈₉−171, [h]₅₇₈−180, [h]₅₄₆

−208, [h]₄₃₆−394, [h]₃₆₅−721. (1R,2R)-

C₅H₈[P(OPh)₂]₂; [h]₅₈₉−50, [h]₅₇₈−52, [h]₅₄₆−60,

[h]₄₃₆−102, [h]₃₆₅−160; (1S,2S)-C₅H₈[P(OPh)₂]₂;

[h]₅₈₉+50, [h]₅₇₈+52, [h]₅₄₆+59, [h]₄₃₆+101, [h]₃₆₅

+160. — The 1,5-cyclooctadiene precursors [(1,5-

C₈H₁₂)Pt(Cl)(X)] (X=Cl [33a,33c], CH₃[33b],

CH₂CMe₃[33d]), and the chelate complexes

[C₅H₈{P(N-pip)₂}₂Pt(Cl)(CH₂CMe₃)]

(8)

and

[C₅H₈{P(N-pip)₂}₂Pt(CH₂CMe₃)₂] (10) [13d] were pre-

pared by the published procedures or slight modiﬁca-

tions thereof. For compound 8, completing NMR data

1

are as follows: H-NMR (CD₂Cl₂): l=1.03 (s; 9 H,

CH₃) 1.35–2.20 (m; 32 H, CCH₂C and PtCH₂C), 2.49–

2.62 (m; 2 H, CH), 3.03–3.58 (m; 16 H, NCH₂C). —

¹³C{¹H}-NMR (CDCl₃): l=22.13, 22.68 [both

ABX-dd, SJ(P,C)=22.5 Hz each; both 1 C₅H₈-C^3,5H₂],

23.81, 23.91, 23.98, 24.04 (all s; all 1 piperidino C⁴H₂),

3

25.77, 25.83, 26.02, 26.14 [all d, J(P,C)=4.4 Hz each;

all 2 piperidino C^3,5H₂], 28.74 [ABX-dd, SJ(P,C)=18.2

Hz; C₅H₈-C⁴H₂), 29.53 [dd, trans-²J(P,C)=117.0, cis-

²J(P,C)=5.1 Hz, ¹⁹⁵Pt satellites not resolved;

PtCH₂C(CH₃)₃], 34.39 [¹⁹⁵Pt-ﬂanked d, ³J(P,C)=2.2,

²J(Pt,C)$14 Hz; PtCH₂C(CH₃)₃], 34.61 [¹⁹⁵Pt-ﬂanked

d, ⁴J(P,C)=5.8, ³J(Pt,C)$30 Hz; PtCH₂C(CH₃)₃],

4. Experimental

4.1. General remarks

All manipulations were performed under nitrogen

using standard Schlenk techniques. Solvents were dis-

tilled from the appropriate drying agents prior to

46.39 (s, 2

piperidino C^2,6H₂), 46.78 [ABX-dd,

SJ(P,C)=50.8 Hz; 1 C₅H₈-C^1,2H], 47.53 (s), 47.84

2

3

[

¹⁹⁵Pt-ﬂanked d, J(P,C)=5.1, J(Pt,C)$17 Hz], 46.56

1

2

3

use. — NMR: Bruker DPX 300 (300.1 MHz for H,

¹⁹⁵Pt-ﬂanked d, J(P,C)=5.1, J(Pt,C)=32.7 Hz] (all

75.5 MHz for ¹³C, 282.4 MHz for ¹⁹F, 121.5 MHz for

³¹P, and 149.2 MHz for ¹¹⁹Sn) at 2092 °C (if not

stated otherwise) with SiMe₄as internal or with CFCl₃,

H₃PO₄or SnMe₄as external standards (downﬁeld posi-

tive); estimated accuracy of couplings to ¹⁹⁵Pt and

^117,119Sn: 95 Hz; ‘SJ(P,C)’: separation of the two most

intense lines in the various ¹³C{¹H} AA%X or ABX

multiplets. — Polarimetry: Perkin–Elmer PE 241(1

dm cells at room temperature (r.t.)); [h]_uin 10 deg cm²

g⁻¹(estimated accuracy: 93%), c in g 100 ml⁻¹. —

Gas chromatography: Hewlett-Packard/Agilent Tech-

nologies GC 5890 II (split injection; Rt bDex cst

column 30 m×0.32 mm (Restek, Bad Homburg, Ger-

many), ﬁlm thickness 0.25 mm; carrier gas 70 kPa H₂;

FID detector).

2 piperidino C^2,6H₂], 55.78 [ABX-dd, SJ(P,C)=85.0

Hz; 1 C₅H₈-C^1,2H].

4.2. Dichloro and alkylchloro complexes

4.2.1. [C₅H₈(PPh₂)₂PtCl₂] (1)

A solution containing 650 mg (1.74 mmol) of [(1,5-

C₈H₁₂)PtCl₂] and 780 mg (1.78 mmol) of C₅H₈(PPh₂)₂

in 35 ml of dichloromethane was stirred at room

temperature (r.t.) overnight. Evaporation of the solvent

left the product as an off-white powder which was freed

from any unreacted starting complex by trituration

with hot acetone and subsequently washed with

ethanol; yield 1.10 g (90%). — ¹H-NMR (CD₂Cl₂):

l=1.14–2.12 (m; 6 H, CH₂), 2.75–2.85 (m; 2 H, CH),

7.39–7.92 (m; 20 H, C₆H₅). — ¹³C{¹H}-NMR

(CD₂Cl₂): l=22.96 [ﬁlled-in AA%X-dd, SJ(P,C)=13.1

Tin(II) chloride (99.99+%, Aldrich) was used as

supplied. — The racemic ligands C₅H₈(PR₂)₂, where

236

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

3

Hz; 2 C₅H₈-C^3,5H₂], 31.31 [t, J(P,C)=8.7 Hz; C₅H₈-

C⁴H₂], 48.31 [ﬁlled-in AA%X-dd, SJ(P,C)=58.1 Hz; 2

C₅H₈-C^1,2H], 124.74 [dd, J(P,C)=62.5, 3.6 Hz], 127.34

[dd, J(P,C)=68.3, 2.9 Hz] (both 2 C₆H₅ipso-C),

129.52 [AA%X-qui, SJ(P,C)=13.1 Hz; 8 C₆H₅meta-C],

132.53, 133.44 (both s; both 2 C₆H₅para-C), 133.83

[AA%X-qui, SJ(P,C)=9.4 Hz], 137.43 [AA%X-qui,

Hz]. — Anal.

Found:

C,

44.29;

H,

3.55.

C₂₉H₂₈Cl₂O₄P₂Pt (768.5). Calc.: C, 45.33; H, 3.67%. —

Samples of higher analytical purity were obtained, if

cis-[(Et₂S)₂PtCl₂] [51] (560 mg, 1.26 mmol, in 20 ml of

CH₂Cl₂) was used as starting material for the ligand

exchange reaction with C₅H₈[P(OPh)₂]₂(700 mg, 1.39

mmol); yield 900 mg (94%). — Found: C, 45.87; H,

3.61%. — With (1R,2R)- and (1S,2S)-C₅H₈[P(OPh)₂]₂

as chelating ligands, the optically pure enantiomers

(R,R)-3 and (S,S)-3 were prepared by the same

method. — Optical rotations (both c=1, CHCl₃):

(R,R)-3; [h]₅₈₉+165, [h]₅₇₈+174, [h]₅₄₆+201, [h]₄₃₆

+384. (S,S)-3; [h]₅₈₉−166, [h]₅₇₈−175, [h]₅₄₆−202,

[h]₄₃₆−383, [h]₃₆₅−717.

SJ(P,C)=11.6 Hz] (both

4

C₆H₅ortho-C). —

³¹P{¹H}-NMR (CD₂Cl₂): l=16.7

[

¹⁹⁵Pt-ﬂanked s,

¹J(Pt,P)=3600 Hz]. — Anal. Found: C, 49.40; H,

4.48. C₂₉H₂₈Cl₂P₂Pt (704.5). Calc.: C, 49.44; H, 4.01%.

4.2.2. [C₅H₈{P(N-pip)₂}₂PtCl₂] (2)

The preparation was carried out as described for 1 by

reacting 160 mg (0.43 mmol) of [(1,5-C₈H₁₂)PtCl₂] with

200 mg (0.43 mmol) of C₅H₈[P(N-pip)₂]₂in 10 ml of

CH₂Cl₂. The crude product was washed with ethanol

and diethyl ether (20 ml each) and puriﬁed further by

crystallization from CH₂Cl₂–n-hexane; yield 240 mg

(77%) of 2 as colorless crystals. — ¹H-NMR (CDCl₃):

l=1.41–1.86 (m; 30 H, CCH₂C), 2.47–2.59 (m; 2 H,

CH), 3.09–3.60 (m; 16 H, NCH₂C). — ¹³C{¹H}-

NMR (CDCl₃): l=21.14 [AA%X-qui, SJ(P,C)=15.3

Hz; 2 C₅H₈-C^3,5H₂), 24.39, 24.59 (both s; both 2 pipe-

ridino C⁴H₂), 26.30 [AA%X-t, SJ(P,C)$25 Hz], 26.67

(br s) (both 4 piperidino C^3,5H₂), 30.74 (s; C₅H₈-C⁴H₂),

47.64, 48.42 (both s; both 4 piperidino C^2,6H₂), 49.9

[badly resolved AA%X-t; 2 C₅H₈-C^1,2H]. — ³¹P{¹H}-

NMR (CDCl₃): l=68.5 [¹⁹⁵Pt-ﬂanked s, ¹J(Pt,P)=

4340 Hz]. — Anal. Found: C, 41.01; H, 6.31; N, 7.36.

C₂₅H₄₈Cl₂N₄P₂Pt (732.6). Calc.: C, 40.99; H, 6.60; N,

7.65%.

4.2.4. rac-[C₅H₈(PPh₂)₂Pt(Cl)(CH₃)] (4) and resol6ed

enantiomers (R,R)-4 and (S,S)-4

A solution of 575 mg (1.31 mmol) of racemic

C₅H₈(PPh₂)₂in 20 ml of dichloromethane was added

dropwise to a solution of 460 mg (1.30 mmol) of

[(1,5-C₈H₁₂)Pt(Cl)(CH₃)] in an equal volume of the

same solvent. After 1 h at ambient temperature, all

volatile material was removed under a dynamic vacuum

to leave a solid residue which was puriﬁed by thorough

trituration, ﬁrst with ethanol (20 ml) and then with

diethyl ether (20 ml); yield 620 mg (70%) of 4 as an

off-white powder. — ¹H-NMR (CD₂Cl₂): l=0.43

3

2

[

¹⁹⁵Pt-ﬂanked dd, J(P,H)=7.5, 3.7, J(Pt,H)=57 Hz;

3 H, PtCH₃], 1.17–2.07 (m; 6 H, CH₂), 2.39–2.89 (m; 2

H, CH), 7.42–7.90 (m; 20 H, C₆H₅). — ¹³C{¹H}-

NMR (CD₂Cl₂): l=7.14 [dd, trans-²J(P,C)=94.5, cis-

²J(P,C)=6.5 Hz, ¹⁹⁵Pt satellites not resolved; PtCH₃],

22.64 [ABX-dd, SJ(P,C)=10.9 Hz], 22.90 [ABX-dd,

SJ(P,C)=12.3 Hz] (both 1 C₅H₈-C^3,5H₂), 30.15 [badly

4.2.3. rac-[C₅H₈{P(OPh)₂}₂PtCl₂] (3) and resol6ed

enantiomers (R,R)-3 and (S,S)-3

resolved

ABX-m;

C₅H₈-C⁴H₂],

44.71[ABX-dd,

This material, which was previously isolated in low

yield from prolonged acidolysis with methanolic HCl of

[C₅H₈{P(OPh)₂}₂Pt(CH₂CMe₃)₂] [13d], formed virtually

quantitatively on combining [(1,5-C₈H₁₂)PtCl₂] (730

SJ(P,C)=45.8 Hz], 50.73 [ABX-dd, SJ(P,C)=65.4

1

Hz] (both 1 C₅H₈-C^1,2H), 124.62 [d, J(P,C)=58.1 Hz;

1 C₆H₅ipso-C], 128.0–128.6 (overlapping doublets; 8

C₆H₅meta-C], 130.17, 130.85, 131.10, 131.69 [all d,

⁴J(P,C)=2.2 Hz each; all 1 C₆H₅para-C], 132.08 [d,

mg, 1.95 mmol) with

a slight excess of rac-

2

C₅H₈[P(OPh)₂]₂(990 mg, 1.97 mmol) in dichloro-

methane (15 ml) as detailed for 1; yield (after tritura-

tion with acetone, followed by washing with ethanol

and diethyl ether) 1.40 g (92%) as off-white microcrys-

tals. — ¹H-NMR (CDCl₃): l=1.73–2.14 (m; 6 H,

CH₂), 2.51–2.58 (m; 2 H, CH), 7.13–7.41 (m; 20 H,

C₆H₅). — ¹³C{¹H}-NMR (CDCl₃): l=21.51 [ﬁlled-in

AA%X-dd, SJ(P,C)=15.3 Hz; 2 C₅H₈-C^3,5H₂], 32.51 (s;

C₅H₈-C⁴H₂), 54.20 [ﬁlled-in AA%X-dd, SJ(P,C)=82.1

Hz; 2 C₅H₈-C^1,2H], 123.00, 123.31 (both s; both 4 C₆H₅

meta-C), 127.79, 127.81 (both s; both 2 C₆H₅para-C),

131.50, 131.83 (both s; both 4 C₆H₅ortho-C), 151.95

[AA%X-t, SJ(P,C)=8.0 Hz], 153.02 [AA%X-t,

SJ(P,C)=7.3 Hz] (both 2 C₆H₅ipso-C). — ³¹P{¹H}-

²J(P,C)=9.4 Hz], 132.90 [d, J(P,C)=8.7 Hz], 136.39

[d, ²J(P,C)=13.1 Hz], 136.67 [d, ²J(P,C)=12.4 Hz] (all

2 C₆H₅ortho-C); remaining ipso-C resonances superim-

posed by meta-C signals. — ³¹P{¹H}-NMR (CD₂Cl₂):

l=21.2 [¹⁹⁵Pt-ﬂanked d, ²⁺³J(P,P)=14, ¹J(Pt,P)=

1

4255 Hz; P trans Cl], 23.3 [¹⁹⁵Pt-ﬂanked d, J(Pt,P)=

1705 Hz; P trans C]. — Anal. Found: C, 52.55; H

5.06. C₃₀H₃₁ClP₂Pt (684.1). Calc.: C, 52.68;

H

4.57%. — The optically active complexes (R,R)-4 and

(S,S)-4 were obtained analogously by combining [(1,5-

C₈H₁₂)Pt(Cl)(CH₃)] with equimolar amounts of

(1R,2R)- or (1S,2S)-C₅H₈(PPh₂)₂. — Optical rotations

(both c=1, CHCl₃): (R,R)-4; [h]₅₈₉−187, [h]₅₇₈

−

196, [h]₅₄₆−224, [h]₄₃₆−401, [h]₃₆₅−701. (S,S)-4;

[h]₅₈₉+186, [h]₅₇₈+194, [h]₅₄₆+222, [h]₄₃₆+396,

[h]₃₆₅+682.

1

NMR (CDCl₃): l=101.3 [¹⁹⁵Pt-ﬂanked s, J(Pt,P)=

4640 Hz]; ref. [13d]: l(CDCl₃)=98.9 [¹J(Pt,P)=4657

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

237

4.2.5. [C₅H₈{P(N-pip)₂}₂Pt(Cl)(CH₃)] (5)

4.2.7. rac-[C₅H₈(PPh₂)₂Pt(Cl)(CH₂CMe₃)] (7) and

resol6ed enantiomers (R,R)-7 and (S,S)-7

A solution composed of 510 mg (1.44 mmol) of

[(1,5-C₈H₁₂)Pt(Cl)(CH₃)] and 680 mg (1.46 mmol) of

C₅H₈[P(N-pip)₂]₂in 30 ml of CH₂Cl₂was stirred at r.t.

overnight. The residue remaining after removal of all

volatiles was washed with ethanol and diethyl ether (20

ml each) and subsequently crystallized from CH₂Cl₂to

give 720 mg (70%) of 5 as colorless crystals. — ¹H-

[(1,5-C₈H₁₂)Pt(Cl)(CH₂CMe₃)] (390 mg; 0.96 mmol)

and 420 mg (0.96 mmol) of rac-C₅H₈(PPh₂)₂were

reacted in 15 ml of CH₂Cl₂as delineated for 5; yield

(after crystallization from CH₂Cl₂–n-pentane) 470 mg

(66%) of

7

as colorless crystals. — ¹H-NMR

(CD₂Cl₂): l=0.69 (s; 9 H, CH₃), 1.11–2.27 (m; 8 H,

CH₂), 2.71–2.90 (m; 2 H, CH), 7.35–7.87 (m; 20 H,

C₆H₅). — ¹³C{¹H}-NMR (CDCl₃): l=22.73 [ABX-t,

SJ(P,C)=13.1 Hz], 23.07 [ABX-t, SJ(P,C)=10.9 Hz]

(both 1 C₅H₈-C^3,5H₂), 29.58 [ABX-dd, SJ(PC)=15.3

NMR (CDCl₃): l=0.46 [¹⁹⁵Pt-ﬂanked dd, J(P,H)=

3

2

8.4, 2.4, J(Pt,H)=52 Hz; 3 H, PtCH₃], 1.37–2.09 (m;

30 H, CCH₂C), 2.10–2.38 (m; 2 H, CH), 2.93–3.43 (m;

16 H, NCH₂C). — ¹³C{³¹P,¹H}-NMR (CDCl₃): l=

0.04 (s, ¹⁹⁵Pt satellites not resolved; PtCH₃), 22.18,

22.90 (both s; both 1 C₅H₈-C^3,5H₂), 24.78, 24.89, 24.91,

25.01 (all s; all 1 piperidino C⁴H₂), 26.59, 26.88, 26.97,

27.18 (all s; all 2 piperidino C^3,5H₂), 30.19 (s; C₅H₈-

C⁴H₂), 47.53, 47.98, 48.98, 49.16 (all s; all 2 piperidino

C^2,6H₂), 49.33, 53.62 (both s; both 1 C₅H₈-C^1,2H). —

4

Hz; C₅H₈-C⁴H₂], 34.83 [¹⁹⁵Pt-ﬂanked d, J(P,C)=5.1,

³J(Pt,C)=26.9 Hz; PtCH₂C(CH₃)₃], 36.08

[

¹⁹⁵Pt-

Hz;

ﬂanked

d,

³J(P,C)=2.2,

²J(Pt,C)$13

PtCH₂C(CH₃)₃], 40.00 [d, trans-²J(P,C)=90.8 Hz, cis-

²J(P,C) not resolved, ¹⁹⁵Pt satellites not resolved;

PtCH₂C(CH₃)₃], 42.30 [ABX-dd, SJ(P,C)=41.4 Hz],

51.54 [ABX-dd, S J(P,C)=66.9 Hz] (both 1 C₅H₈-

C^1,2H), 128.0–128.6 (overlapping doublets; 8 C₆H₅

³¹P{¹H}-NMR (CDCl₃): l=78.4 [¹⁹⁵Pt-ﬂanked d,

2+

3J(P,P)=17, ¹J(Pt,P)=5000 Hz; P trans Cl], 106.0

[

¹⁹⁵Pt-ﬂanked d, ¹J(Pt,P)=2215 Hz; P trans C]. —

meta-C), 130.07 (s; 1 C₆H₅para-C), 130.84 [d,

4

Anal. Found: C, 43.59; H, 7.76; N, 7.60.

C₂₆H₅₁ClN₄P₂Pt (712.2). Calc.: C, 43.85; H, 7.22; N,

7.87%.

⁴J(P,C)=2.2 Hz; 2 C₆H₅para-C], 131.91 [d, J(P,C)=

2.2 Hz; 1 C₆H₅para-C], 132.65, 133.12 [both d,

²J(P,C)=9.4 Hz each; both 2 C₆H₅ortho-C], 136.14 [d,

²J(P,C)=12.4 Hz; 2 C₆H₅ortho-C], 136.88 [¹⁹⁵Pt-

2

3

4.2.6. [C₅H₈{P(OPh)₂}₂Pt(Cl)(CH₃)] (6)

The complex was prepared as described for 5 by

ﬂanked d, J(P,C)=11.6, J(Pt,C)=45.8 Hz; 2 C₆H₅

ortho-C]; ipso-C resonances partially obscured by over-

lapping meta-C doublets. — ³¹P{¹H}-NMR (CD₂Cl₂):

reacting

840

mg

(2.37

mmol)

of

[(1,5-

C₈H₁₂)Pt(Cl)(CH₃)] with 1.20

g

(2.4 mmol) of

l=19.9

[

¹⁹⁵Pt-ﬂanked

AB-d,

²⁺³J(P,P)=14,

C₅H₈[P(OPh)₂]₂in 30 ml of dichloromethane; yield

(after washing with ethanol and diethyl ether) 1.15 g

(65%) of 6 as an off-white powder. — ¹H-NMR

¹J(Pt,P)=4495 Hz; P trans Cl], 20.4 [¹⁹⁵Pt-ﬂanked AB-

1

d, J(Pt,P)=1495 Hz; P trans C]. — Anal. Found: C,

55.39; H, 5.63. C₃₄H₃₉ClP₂Pt (740.1). Calc.: C, 55.17;

H, 5.31%. — Virtually the same procedures were em-

ployed for the synthesis of the enantiopure complexes

(R,R)-7 and (S,S)-7. — Optical rotations: (R,R)-7;

[h]₅₈₉−146, [h]₅₇₈−153, [h]₅₄₆−175, [h]₄₃₆−323

(c=1, CHCl₃). (S,S)-7; [h]₅₈₉+138, [h]₅₇₈+145,

[h]₅₄₆+169, [h]₄₃₆+304 (c=1, CHCl₃); [h]₅₈₉+137,

[h]₅₇₈+144, [h]₅₄₆+167, [h]₄₃₆+305, [h]₃₆₅+581

(c=0.5, CH₂Cl₂).

3

(CDCl₃): l=0.07 [¹⁹⁵Pt-ﬂanked dd, J(P,H)=9.8, 2.3,

²J(Pt,H)=52 Hz; 3 H, PtCH₃], 1.38–2.14 (m; 6 H,

CH₂), 2.37–2.42 (m; 2 H, CH), 6.95–7.35 (m; 20 H,

C₆H₅). — ¹³C{¹H}-NMR (CDCl₃): l=1.91 [dd,

trans-²J(P,C)=123.6, cis-²J(P,C)=4.4 Hz, ¹⁹⁵Pt satel-

lites not resolved; PtCH₃], 19.81 [dd, J(P,C)=19.6, 5.9

Hz], 20.55 [dd, J(P,C)=19.7, 6.3 Hz] (both 1 C₅H₈-

C^3,5H₂), 29.73 [ABX-dd, SJ(P,C)=18.8 Hz; C₅H₈-

C⁴H₂], 53.98 [dd, J(P,C)=37.8, 13.8 Hz], 54.25 [dd,

J(P,C)=66.1, 22.3 Hz] (both 1 C₅H₈-C^1,2H), 120.56 [d,

4.2.8. [C₅H₈{P(OPh)₂}₂Pt(Cl)(CH₂CMe₃)] (9)

3

³J(P,C)=5.1 Hz], 120.86 [d, J(P,C)=5.2 Hz], 121.50

This complex was originally obtained by controlled

protolytic cleavage of the metal–carbon bond of the

dineopentyl [C₅H₈{P(OPh)₂}₂Pt(CH₂CMe₃)₂] [13d]. Al-

ternatively, it can be prepared by combining [(1,5-

C₈H₁₂)Pt(Cl)(CH₂CMe₃)] (440 mg, 1.08 mmol) with

3

[d, J(P,C)=3.7 Hz], 122.25 [d, J(P,C)=3.8 Hz] (all 2

5

C₆H₅ortho-C), 125.10 (s), 125.29 [d, J(P,C)=1.4 Hz],

125.50 [d, ⁵J(P,C)=1.5 Hz], 125.76 [d, ⁵J(P,C)=2.1

Hz] (all 1 C₆H₅para-C), 129.7–129.9 (overlapping dou-

blets; 8 C₆H₅meta-C), 151.53 [ABX-d, SJ(P,C)=8.0

Hz], 151.86 [ABX-d, SJ(P,C)=3.9 Hz], 151.99 (decep-

tively simple s, SJ(P,C)$0 Hz], 152.68 [ABX-d,

SJ(P,C)=2.2 Hz] (all 1 C₆H₅ipso-C). — ³¹P{¹H}-

NMR (CDCl₃): l=112.0 [¹⁹⁵Pt-ﬂanked d, ²⁺³J(P,P)=

C₅H₈[P(OPh)₂]₂

(550

mg,

1.09

mmol)

in

dichloromethane (15 ml, r.t., overnight). Removal of all

volatiles, followed by stirring the residue under ethanol

(20 ml) afforded 690 mg (79%) of the product as

colorless microcrystals. — ¹H-NMR (CD₂Cl₂): l=

0.78 (s; 9 H, CH₃), 1.96–1.24 (m; 8 H, CH₂), 2.28–2.31

(m; 2 H, CH), 7.15–7.44 (m; 20 H, C₆H₅). —

¹³C{¹H}-NMR (CDCl₃): l=19.25 [dd, J(P,C)=18.2,

5.1 Hz], 21.60 [dd, J(P,C)=18.2, 7.3 Hz] (both 1

1

7, J(Pt,P)=5635 Hz; P trans Cl], 155.1 [¹⁹⁵Pt-ﬂanked

1

d, J(Pt,P)=2140 Hz; P trans C]. — Anal. Found: C,

48.09; H, 4.07. C₃₀H₃₁ClO₄P₂Pt (748.1). Calc.: C, 48.17;

H, 4.18%.

238

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

C₅H₈-C^3,5H₂), 29.38 [ABX-dd, SJ(P,C)=17.6 Hz;

C₅H₈-C⁴H₂], 34.37 [dd, trans-²J(P,C)=122.8, cis-

²J(P,C)=3.6 Hz, ¹⁹⁵Pt satellites not resolved;

PtCH₂C(CH₃)₃], 34.53 [¹⁹⁵Pt-ﬂanked d, ⁴J(P,C)=8.3,

¹H-NMR (CDCl₃): l=0.16

[

¹⁹⁵Pt-ﬂanked d,

³J(P,H)=9.8, ²J(Pt,H)=42 Hz; 3 H, PtCH₃], 1.30–

2.22 (m; 6 H, CH₂), 2.43–2.69 (m; 2 H, CH), 7.11–7.44

(m; 20 H, C₆H₅). — ¹³C{¹H}-NMR (CD₂Cl₂): l=

³J(Pt,C)=26.3 Hz; PtCH₂C(CH₃)₃], 35.58

[

¹⁹⁵Pt-

Hz;

1.88

[

¹⁹⁵Pt-ﬂanked dd, trans-²J(P,C)=111.2, cis-

1

ﬂanked

d,

³J(P,C)=2.2,

²J(Pt,C)$16

²J(P,C)=3.6, J(Pt,C)=440 Hz; PtCH₃], 19.64, 20.27

[both dd, J(P,C)=18.9, 5.8 Hz each; both 1 C₅H₈-

C^3,5H₂], 28.50 [ABX-dd, SJ(P,C)=20.3 Hz; C₅H₈-

C⁴H₂], 119.23 [d, ³J(P,C)=5.8 Hz], 119.76 [d,

³J(P,C)=5.1 Hz] (both 2 C₆H₅ortho-C), 120.60 (ABX-

t, SJ(P,C)=4.4 Hz; 4 C₆H₅ortho-C), 124.63 (s; 1 C₆H₅

PtCH₂C(CH₃)₃], 53.73 [dd, J(P,C)=33.4, 12.3 Hz],

54.16 [dd, J(P,C)=59.6, 22.8 Hz] (both 1 C₅H₈-C^1,2H),

120.64 [d, ³J(P,C)=4.4 Hz], 120.91 [d, ³J(P,C)=4.4

3

Hz], 121.14 [d, J(P,C)=5.1 Hz], 121.84 [d, J(P,C)=

3.6 Hz] (all 2 C₆H₅ortho-C), 124.97, 125.08, 125.26,

125.53 [all d, ⁵J(P,C)=1.4 Hz each; all 1 C₆H₅para-C),

129.5–129.9 (overlapping doublets; 8 C₆H₅meta-C),

151.80 [ABX-d, SJ(P,C)=10.9 Hz], 152.02 [ABX-d,

SJ(P,C)=3.7 Hz], 152.18 (ABX-d, SJ(P,C)=12.3 Hz],

152.67 [ABX-d, SJ(P,C)=2.9 Hz] (all 1 C₆H₅ipso-

para-C), 125.16 (s;

2 C₆H₅para-C), 125.54 (d,

⁵J(P,C)=2.2 Hz; 1 C₆H₅para-C), 129.2, 129.4 (both

overlapping doublets; 2+6 C₆H₅meta-C), 150.36

[ABX-d,

SJ(P,C)=8.7

Hz],

150.96

[ABX-d,

SJ(P,C)=9.4 Hz], 151.20 (ABX-d, SJ(P,C)=15.3 Hz],

152.34 [ABX-d, SJ(P,C)=2.9 Hz] (all 1 C₆H₅ipso-C);

CH resonances obscured by solvent signal; CF₃not

detected. — ³¹P{¹H}-NMR (CD₂Cl₂): l=99.5 [¹⁹⁵Pt-

C). — ³¹P{¹H}-NMR (CD₂Cl₂): l=107.4

[

¹⁹⁵Pt-

1

ﬂanked d, ²⁺³J(P,P)=8, J(Pt,P)=6085 Hz; P trans

1

Cl], 156.6 [¹⁹⁵Pt-ﬂanked d, J(Pt,P)=1905 Hz; P trans

1

C]; ref. [13d]: l(C₆D₆)=105.0

[

²⁺³J(P,P)=11,

ﬂanked d, ²⁺³J(P,P)=11, J(Pt,P)=6565 Hz; P trans

¹J(Pt,P)=6142 Hz], 164.5 [¹J(Pt,P)=1905 Hz]. —

Anal. Found: C, 50.76; H, 5.16. C₃₄H₃₉ClO₄P₂Pt

(804.1). Calc.: C, 50.78; H, 4.89%.

O], 164.7 [¹⁹⁵Pt-ﬂanked d, J(Pt,P)=2245 Hz; P trans

1

C]. — Anal. Found: C, 43.47; H, 3.74; S, 3.67.

C₃₁H₃₁F₃O₇P₂PtS (861.7). Calc.: C, 43.21; H, 3.63; S,

3.72%.

4.3. Triﬂate deri6ati6es

4.3.3. [C₅H₈(PPh₂)₂Pt(CH₂CMe₃)(OSO₂CF₃)] (13)

4.3.1. [C₅H₈(PPh₂)₂Pt(CH₃)(OSO₂CF₃)] (11)

A

solution of 280 mg (0.38 mmol) of

AgO₃SCF₃(155 mg; 0.60 mol) was suspended in 20

ml of dichloromethane in the dark. A solution of 410

mg (0.60 mmol) of [C₅H₈(PPh₂)₂Pt(Cl)(CH₃)] (4) in 30

ml CH₂Cl₂was added dropwise within 45 min and the

resulting mixture was stirred for an additional 30 min

at ambient conditions. Precipitated silver chloride was

removed by ﬁltration over Celite and the concentrated

ﬁltrate was diluted with n-pentane. The product sepa-

rated from solution as an off-white solid which was

collected after allowing the mixture to stand overnight

at −20 °C in order to complete precipitation; yield

300 mg (63%). — ¹H-NMR (CD₂Cl₂): l=0.48 [¹⁹⁵Pt-

[C₅H₈(PPh₂)₂Pt(Cl)(CH₂CMe₃)] (7) in CH₂Cl₂was

stirred with 98 mg (0.38 mmol) of AgO₃SCF₃for 2.5 h

at r.t. in the dark. Silver chloride was ﬁltered off over

Celite and the ﬁltrate was evaporated to dryness to

leave 140 mg (43%) of 13 as a beige solid. — ¹H-

NMR (CD₂Cl₂): l=0.69 (s; 9 H, CH₃), 0.95–2.40 (m;

8 H, CH₂), 2.76–2.94 (m; 2 H, CH), 7.40–7.92 (m; 20

H, C₆H₅). — ³¹P{¹H}-NMR (CD₂Cl₂): l=15.2 [¹⁹⁵Pt-

1

ﬂanked d, ²⁺³J(P,P)=13, J(Pt,P)=5310 Hz; P trans

1

O], 31.0 [¹⁹⁵Pt-ﬂanked d, J(Pt,P)=1615 Hz; P trans

C]. — Anal. Found (after recrystallization from etha-

nol): C, 49.42; H, 4.65; S, 3.67. C₃₅H₃₉F₃O₃P₂PtS

(853.7). Calc.: C, 49.24; H, 4.60; S, 3.76%.

3

2

ﬂanked dd, J(P,H)=7.7, 1.6, J(Pt,H)=45 Hz; 3 H,

PtCH₃], 1.12–2.07 (m; 6 H, CH₂), 2.44–2.60 (m; 2 H,

CH), 7.40–7.98 (m; 20 H, C₆H₅). — ¹⁹F{¹H}-NMR

(CDCl₃): l= −77.88 (s). — ³¹P{¹H}-NMR (CD₂Cl₂):

l=17.3 [¹⁹⁵Pt-ﬂanked d, ²⁺³J(P,P)=13, ¹J(Pt,P)=

4.3.4. [v-Cl{C₅H₈(PPh₂)₂PtCH₃}₂]O₃SCF₃(14)

At −60 °C, 60 mg (0.23 mmol) of AgO₃SCF₃was

added to a solution of 155 mg (0.23 mmol) of

[C₅H₈(PPh₂)₂Pt(Cl)(CH₃)] (4) in 20 ml of CH₂Cl₂. After

warming to r.t., the mixture was stirred for 1 h in the

dark, ﬁltered over Celite and evaporated. ³¹P{¹H}-

NMR spectroscopy showed the residual material to be

a 3:1 mixture of products 11 and 14. Crystallization of

the solid from a dichloromethane–diethyl ether solvent

mixture yielded colorless single-crystals of complex 14

as an addition compound containing 0.5 mol of lattice

diethyl ether per formula unit, [m-Cl{C₅H₈(PPh₂)₂-

PtCH₃}₂]O₃SCF₃·0.5 Et₂O (14·0.5 Et₂O). — ³¹P{¹H}-

NMR (CD₂Cl₂): l=21.11 [2 coinciding ¹⁹⁵Pt-ﬂanked

1

4975 Hz; P trans O], 34.3 [¹⁹⁵Pt-ﬂanked d, J(Pt,P)=

1810 Hz; P trans C]. — Anal. Found: C, 47.07; H,

3.79; S, 3.76. C₃₁H₃₁F₃O₃P₂PtS (797.7). Calc.: C, 46.68;

H, 3.92; S, 4.02%.

4.3.2. [C₅H₈{P(OPh)₂}₂Pt(CH₃)(OSO₂CF₃)] (12)

Silver triﬂate (100 mg; 0.38 mmol) and 290 mg (0.38

mmol) of [C₅H₈{P(OPh)₂}₂Pt(Cl)(CH₃)] (6) were al-

lowed to interact in 40 ml of dichloromethane as de-

scribed for 11. The product was isolated from the

ﬁltered solution by removal of all volatile material;

yield 260 mg (77%) of 12 as an off-white powder. —

1

doublets, ²⁺³J(P,P)=13, J(Pt,P)=4625 Hz; 2 P trans

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

239

1

m-Cl], 28.6 [¹⁹⁵Pt-ﬂanked d, J(Pt,P)=1770 Hz], 29.0

¹J(Pt,P)=4660 Hz; P trans Sn], 156.4 [¹⁹⁵Pt-ﬂanked s

1

2

(br), J(Pt,P)=2415 Hz; P trans C]; J(^117,119Sn,P) not

resolved. — ¹¹⁹Sn{¹H}-NMR (CD₂Cl₂, −70 °C):

l=52.9 [dd with ¹⁹⁵Pt satellites, trans-²J(¹¹⁹Sn,P)=

[

¹⁹⁵Pt-ﬂanked d, J(Pt,P)=1760 Hz] (both 1 P trans C].

4.4. Trichlorostannato complexes [C₅H₈(PPh₂)₂Pt-

(CH₃)(SnCl₃)] (15), [C₅H₈(PPh₂)₂Pt(Cl)(SnCl₃)] (16),

[C₅H₈{P(OPh)₂}₂Pt(CH₃)(SnCl₃)] (17), [C₅H₈-

{P(OPh)₂}₂Pt(Cl)(SnCl₃)] (18), [C₅H₈(PPh₂)₂-

Pt(SnCl₃)₂] (19), and [C₅H₈{P(OPh)₂}₂Pt(SnCl₃)₂] (20)

4760,

cis-²J(¹¹⁹Sn,P)=295,

¹J(Pt,¹¹⁹Sn)=18870

Hz]. — 18; ³¹P{¹H}-NMR (CDCl₃): l=110.5 [¹⁹⁵Pt-

ﬂanked d, ²⁺³J(P,P)=18, J(Pt,P)=4455 Hz; P trans

1

Cl], 120.8 [¹⁹⁵Pt-ﬂanked d, J(Pt,P)=3830 Hz; P trans

1

2

Sn]; J(^117,119Sn,P) not resolved. — 3; ³¹P{¹H}-NMR

To 250 mg (0.37 mmol) of [C₅H₈(PPh₂)₂Pt(Cl)(CH₃)]

(4) in 20 ml of acetone was added an equimolar quan-

tity of anhydrous tin(II) chloride (70 mg). The resulting

yellow solution was stirred for 10 min at r.t. and then

reduced in volume. Layering with diethyl ether caused

the deposition of crystals shown by ³¹P{¹H}-NMR as

well as by an X-ray crystallographic study of a selected

specimen (see below) to be a mixture of [C₅H₈(PPh₂)₂-

Pt(CH₃)(SnCl₃)], (15) (ꢀ52%), [C₅H₈(PPh₂)₂Pt(Cl)-

(SnCl₃)], (16) (ꢀ20%; crystal structure analysis), and

[C₅H₈(PPh₂)₂PtCl₂], (1) (ꢀ28%). The identity of the

latter two complexes was independently conﬁrmed by

combining equimolar amounts of 1 (150 mg, 0.21

mmol) and SnCl₂(40 mg, 0.21 mmol) in 20 ml of

CH₂Cl₂, which furnished the insertion product 12 to-

gether with unreacted dichloro complex 1 in the molar

ratio 1:1. — 15; ¹H-NMR ([D₆]acetone): l=0.59

(CDCl₃): l=101.0 [¹⁹⁵Pt-ﬂanked s, ¹J(Pt,P)=4645

Hz]. — Thermal treatment of 4 and 6 (0.1 mmol each)

with tin(II) chloride in 1:1 stoichiometry in toluene (20

ml) at 80 °C for 16–72 h yielded mixtures containing

the dichloro complexes 1/3 together with the

bis(trichlorostannates) [C₅H₈(PR₂)₂Pt(SnCl₃)₂] (R=Ph,

19; OPh, 20) as dominating products and the mono-

trichlorostannates 15/16 and 17/18 as minor con-

stituents. — 19; ³¹P{¹H}-NMR (CDCl₃): l=27.4

1

[

¹⁹⁵Pt- and ^117,119Sn- ﬂanked s, J(Pt,P)=2515, trans-

²J(¹¹⁷Sn,P)=2005,

trans-²J(¹¹⁹Sn,P)=2095,

cis-

²J(¹¹⁷Sn,P)=122, cis-²J(¹¹⁹Sn,P)=166 Hz]. — 20;

³¹P{¹H}-NMR (CDCl₃): l=143.8 [¹⁹⁵Pt-ﬂanked s,

¹J(Pt,P)=3535 Hz]; J(^117,119Sn,P) not resolved.

2

4.5. Exemplary hydroformylation procedure

[

¹⁹⁵Pt-ﬂanked ABX-t, SJ(P,H)=12.2, ²J(Pt,H)=59

A 10-ml Schlenk tube equipped with a small mag-

netic stirring bar was charged with platinum catalyst

(typically 0.012–0.013 mmol) and anhydrous tin(II)

chloride (ꢀ0.025 mmol). [D₈]toluene (3 ml) and sty-

rene (2.2 mmol) were added and the tube was inserted

into an argon-ﬁlled 100-ml stainless steel autoclave. The

autoclave was sealed, pressurized, and vented several

times with a 1:1 CO/H₂synthesis gas mixture (Messer

Griesheim; 99.999% H₂, 99.997% CO) and subsequently

pressurized (usually to 80 bar) and heated with stirring

in an oil bath (typically at 80 °C). At the end of the

reaction, the autoclave was cooled, the pressure was

vented and the mixture of products was analyzed by

¹H-NMR spectroscopy. Conversions and product com-

positions were determined on the basis of the integra-

tions of the PhCHꢂCH₂, PhCH(CH₃)CHO, PhCH₂-

CH₂CHO, PhCH(CH₃)CH₂OH, PhCH₂CH₂CH₂OH,

and PhCH₂CH₃signals. The branched-to-normal ratios

of the aldehydes were estimated by integrating the

ꢀCHO signals, l$9.2 (t) for the normal and 9.3 (d) for

the branched, those of the alcohols by comparing the

intensities of the individual CH₂and CH₃resonances.

Enantiomeric excesses were measured by gas chro-

matography following NaBH₄reduction of the alde-

hydes to the corresponding alcohols. Absolute

conﬁgurations were determined by comparing the re-

tention times of the products with those of optically

pure (R)-(−) and (S)-(+)-2-phenylpropanol.

Hz; 3 H, PtCH₃], 1.16–1.44, 1.76–1.89, 1.98–2.07 (all

m; all 2 H, CH₂), 2.82–3.17 (m; 2 H, CH), 7.36–7.90

(m; 20 H, C₆H₅). — ³¹P{¹H}-NMR (CDCl₃): l=25.7

1

[

¹⁹⁵Pt-ﬂanked d, ²⁺³J(P,P)=17, J(Pt,P)=1780 Hz; P

1

trans C], 27.9 [¹⁹⁵Pt-ﬂanked d, J(Pt,P)=3510 Hz; P

trans Sn]; J(^117,119Sn,P) not resolved. — 16; ³¹P{¹H}-

2

NMR (CD₂Cl₂): l=18.1 [¹⁹⁵Pt- and ^117,119Sn-ﬂanked d,

²⁺³J(P,P)=11, ¹J(Pt,P)=3353, cis-²J(^117,119Sn,P)=

235 Hz; P trans Cl], 25.1 [d with ¹⁹⁵Pt, ¹¹⁷Sn, and ¹¹⁹Sn

satellites, ¹J(Pt,P)=3335, trans-²J(¹¹⁷Sn,P)=3850,

trans-²J(¹¹⁹Sn,P)=4030 Hz; P trans Sn]; data from

[C₅H₈(PPh₂)₂PtCl₂]–SnCl₂reaction. — 1; ³¹P{¹H}-

NMR (CD₂Cl₂): l=17.3 [¹⁹⁵Pt-ﬂanked s, ¹J(Pt,P)=

3600 Hz]. — The reaction between [C₅H₈{P(OPh)₂}₂-

Pt(Cl)(CH₃)], 6 (200 mg, 0.26 mmol), and tin(II) chlo-

ride (50 mg, 0.26 mmol) in acetone (30 ml) was initially

run at −20 °C. Evaporation of the solvent at this

temperature left an orange–yellow residue which

¹¹⁹Sn{¹H}- and ³¹P{¹H}-NMR showed to be largely

pure [C₅H₈{P(OPh)₂}₂Pt(CH₃)(SnCl₃)] (17), only

slightly contaminated by traces of [C₅H₈{P(OPh)₂}₂-

Pt(Cl)(SnCl₃)] (18). Re-dissolution of this material in

acetone at ambient temperature, followed by layering

the mixture with n-hexane, resulted in the precipitation

of

a

reddish solid containing [C₅H₈{P(OPh)₂}₂-

Pt(CH₃)(SnCl₃)], (17) (ꢀ56%), accompanied by

[C₅H₈{P(OPh)₂}₂Pt(Cl)(SnCl₃)], (18) (ꢀ26%), and

[C₅H₈{P(OPh)₂}₂PtCl₂}], (3) (ꢀ18%). — 17; ³¹P{¹H}-

NMR (CDCl₃): l=127.3

[

¹⁹⁵Pt-ﬂanked

s

(br),

240

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

4.6. X-Ray crystallographic studies

each, so that the existence of the ion as a racemate or

a meso compound could not be distinguished. The

triﬂate anion of this structure showed positional disor-

der about its SꢀC axis which was resolved by employing

occupancies of 0.6 for the ﬁrst and 0.4 for the second

anion and by restraining the two CF₃SO₃groups so

that their staggered conformations have 3m symmetry

and are the same as each other. The Et₂O molecule of

crystallization was only poorly deﬁned and had to be

reﬁned with CꢀO and CꢀC bond lengths restrained to

their ideal values. The trichlorostannate ligand attached

to platinum atom Pt(2) in structure 16 displayed three-

fold rotational disorder about the Pt(2)ꢀSn(2) bond

with occupancies of 0.45, 0.20, and 0.35 for the particu-

lar chlorine positions in the ꢀSnCl⁽⁶⁾Cl⁽⁷⁾Cl⁽⁸⁾,

ꢀSnCl^(6a)Cl^(7a)Cl^(8a), and ꢀSnCl^(6b)Cl^(7b)Cl^(8b)groups.

Single-crystals of the complexes studied by X-ray

diffraction were grown from CH₂Cl₂–n-hexane (2),

CH₂Cl₂–diethyl ether (5, 14·0.5 Et₂O), CH₂Cl₂–n-pen-

tane (7), acetone [8, (R,R)-3, (S,S)-3], methanol (9),

acetone–THF (10), ethanol (13), and acetone–diethyl

ether (16), respectively. The measurements were made

at 2092 °C on a Nonius MACH 3 diffractometer

using graphite-monochromated Mo–K_aradiation (u=

,

0.71073 A): orientation matrices from the setting angles

of 25 centered medium-angle reﬂections; collection of

the diffraction intensities by ꢀ scans; data corrected for

absorption by scans [52]. The structures were solved

by direct methods and subsequently reﬁned by full-ma-

trix least-squares procedures on F²with allowance for

anisotropic thermal motion of all non-hydrogen atoms

employing the WinGX package [53] and the relevant

programs (^SIR-97 [54], SHELXL-97 [55], ORTEP-3 [56])

implemented therein. H atoms were included in the

ﬁnal structural models assuming ideal geometry and

using appropriate riding models. According to the U_ij

values of the symmetry-related CH carbon atoms of 10,

a twofold spatial disorder was suggested for these

atoms, which was accounted for by assigning the car-

bon positions C(6a) and C(6b) split occupancies of 0.3

and 0.7, respectively. The ring carbon atoms of the

binuclear cation of complex 14·0.5 Et₂O, C(2)/C(2a),

C(3)/C(3a), C(32)/C(32a), C(33)/C(33a) were similarly

disordered over two sites with occupation factors of 0.5

5. Supplementary material

Crystallographic data (excluding structure factors)

for the structures reported in this paper (Tables 8–10)

have been deposited with the Cambridge Crystallo-

graphic Data Centre and allocated the deposition num-

bers

CCDC-149809

(2),

CCDC-149810

(5),

CCDC-149811 (7), CCDC-149814 (8), CCDC-149815

(9), CCDC-149812 (10), CCDC-149816 (13), CCDC-

149813 (14·0.5Et₂O), CCDC-149817 (16), CCDC-

154353 [(R,R)-3], and CCDC-154354 [(S,S)-3]. Copies

of this information may be obtained free of charge

Table 8

Selected crystallographic data for complexes 2, 5, 7, and 8

2

5

7

8

Formula

M_r

C

732.6

₂₅H₄₈Cl₂N₄P₂Pt

C₂₆H₅₁ClN₄P₂Pt

712.2

C₃₄H₃₉ClP₂Pt

740.1

C₃₀H₅₉ClN₄P₂Pt

768.3

Crystal size (mm)

Crystal system

Space group

0.40×0.28×0.28

tetragonal

0.55×0.10×0.10

monoclinic

P2₁/c (No. 14)

11.699(3)

17.234(2)

14.829(1)

90.66(5)

2990(1)

4

1.582

4.911

0.33×0.28×0.10

monoclinic

P2₁/n (No. 14)

10.5420(5)

15.043(2)

20.005(1)

96.499(4)

3152.0(4)

4

0.49×0.45×0.28

monoclinic

P2₁/c (No. 14)

9.8120(9)

18.3970(8)

18.794(4)

93.44(1)

3386(1)

4

1.507

4.342

(

I42d (No. 122)

,

a (A)

21.171(1)

13.5018(8)

90

,

b (A)

,

c (A)

i (°)

3

,

V (A )

Z

6052(1)

8

1.608

4.940

0.2426

d_calc(g cm⁻³

)

1.560

4.659

0.3085

v(Mo–K_a) (mm⁻¹

T_min

)

0.2918

0.0880

T_max

0.3384

0.6042

0.6530

0.2750

q range (°)

h k l range

2.635q525.97

−26 26, 0 26, 0 16

6249

2975 (0.0516)

2574

155/2975

0.0679

0.0300

2.105q524.00

0 13, 0 19, −16 16

4939

4689 (0.0974)

2895

308/4689

0.2044

0.0825

2.055q526.97

−13 13, 0 19, 0 25

7053

6861 (0.0293)

4180

346/6861

0.0716

0.0371

2.545q525.08

−11 11, 0 21, −22 0

6195

6003 (0.0208)

4523

346/6003

0.0728

0.0341

Reﬂections collected

Unique reﬂections (R_int

Intensities I\2|(I)

Parameter/F_oratio

wR₂of F²(all data)

R₁of F [I\2|(I)]

)

Goodness of ﬁt on F²

1.022

1.123

1.011

1.023

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

241

Table 9

Selected crystallographic data for complexes 9, 10, 13, and 14·0.5 Et₂O

9

10

13

14·0.5 Et₂O

Formula

M_r

C₃₄H₃₉ClO₄P₂Pt

804.1

C₃₅H₇₀N₄P₂Pt

804.0

C₃₅H₃₉F₃O₃P₂PtS

853.7

C₆₃H₆₇ClF₃O_3.5P₄Pt₂S

1518.7

Crystal size (mm)

Crystal system

Space group

0.48×0.28×0.15

monoclinic

P2₁/c (No. 14)

10.136(2)

15.011(1)

22.596(2)

90

90.40(1)

90

3438(1)

0.20×0.18×0.15

orthorhombic

Pbcn (No. 60)

10.0576(4)

17.515(3)

21.271(1)

90

3747(1)

4

0.35×0.13×0.10

monoclinic

P2₁/c (No. 14)

10.288(2)

16.208(1)

21.401(1)

90

99.50(1)

90

3520(1)

0.33×0.20×0.03

triclinic

(

P1 (No. 2)

,

a (A)

9.264(2)

16.299(5)

20.833(4)

77.46(2)

81.95(1)

89.99(1)

3038(1)

,

b (A)

,

c (A)

h (°)

i (°)

k (°)

3

,

V (A )

Z

4

2

d_calc(g cm⁻³

)

1.554

4.287

0.2328

1.425

3.858

0.5125

1.611

4.186

0.3221

1.660

4.838

0.2261

v(Mo–K_a) (mm⁻¹

T_min

)

T_max

0.5657

0.5953

0.6796

0.6996

q range (°)

h k l range

2.585q526.97

0 12, 0 19, −28 28

7885

7456 (0.0344)

5139

382/7465

0.0725

0.0408

2.525q529.96

−1 14, −1 24, −1 29

6672

5448 (0.0313)

2617

203/5448

0.0792

0.0445

2.515q525.07

−12 12, 0 19, 0 25

6427

6249 (0.0468)

4133

409/6249

0.0851

0.0483

2.505q524.97

0 11, −19 19, −24 24

11364

10 643 (0.0531)

6071

642/10 643

0.1397

0.0622

Reﬂections collected

Unique reﬂections (R_int

Intensities I\2|(I)

Parameter/F_oratio

wR₂of F²(all data)

R₁of F [I\2|(I)]

)

Goodness of ﬁt on F²

1.028

1.023

1.021

1.012

Table 10

Selected crystallographic data for complexes 16, (R,R)-3, and (S,S)-3

16

(R,R)-3

(S,S)-3

Formula

M_r

C

894.0

₂₉H₂₈Cl₄P₂PtSn

C₂₉H₂₈Cl₂O₄P₂Pt

768.4

C₂₉H₂₈Cl₂O₄P₂Pt

768.4

Crystal size (mm)

Crystal system

Space group

0.40×0.20×0.08

monoclinic

P2₁/c (No. 14)

22.019(1)

14.794(1)

22.210(1)

119.366(5)

6305(1)

0.47×0.36×0.34

monoclinic

P2₁(No. 4)

10.8014(8)

14.889(3)

18.831(1)

103.312(6)

2947.1(6)

4

0.50×0.50×0.28

monoclinic

P2₁(No. 4)

10.8031(5)

14.890(1)

18.848(3)

103.31(1)

2950.4(5)

4

,

a (A)

,

b (A)

,

c (A)

i (°)

3

,

V (A )

Z

8

d_calc(g cm⁻³

)

1.884

5.683

0.2096

1.732

5.084

0.1985

1.730

5.078

0.1856

v(Mo–K_a) (mm⁻¹

T_min

)

T_max

0.6592

0.2768

0.3305

q range (°)

h k l range

2.105q525.18

0 26, 0 17, −26 23

11 628

11 315 (0.0681)

4905

721/11 315

0.1873

0.0824

2.225q528.17

−14 0, 0 19, −25 25

15 778 ^a

14 447 (0.0394)

10 103

685/14 447

0.1154

0.0520

2.595q527.97

−14 0, 0 19, −24 24

15 496 ^a

14 209 (0.0426)

9809

685/14 209

0.1052

0.0540

Reﬂections collected

Unique reﬂections (R_int

Intensities I\2|(I)

Parameter/F_oratio

wR₂of F²(all data)

R₁of F [I\2|(I)]

)

Goodness of ﬁt on F²

1.013

1.006

1.025

Absolute structure parameter x [57]

0.003(9)

0.014(10)

^aIncluding Friedel pairs.

242

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

(e) K. Nozaki, H. Takaya, T. Hiyama, Top. Catal. 4 (1998) 175;

(f) K. Nozaki, F. Shibahara, Y. Itoi, E. Shirakawa, T. Ohta, H.

Takaya, T. Hiyama, Bull. Chem. Soc. Jpn. 72 (1999) 1911.

[9] D. Gleich, R. Schmid, W.A. Herrmann, Organometallics 17

(1998) 4828.

from The Director, CCDC, 12 Union Road, Cam-

bridge CB2 1EZ, UK (Fax: +44-1223-336033; e-mail:

deposit@ccdc.cam.ac.uk).

[10] (a) G. Francio, W. Leitner, Chem. Commun. (1999) 1663;

(b) W. Leitner, S. Kainz, D. Koch, G. Francio (Studi-

engesellschaft Kohle m.b.H., Germany), Ger. Offen. DE

19853748, 2000 [Chem. Abstr. 133 (2000) 4527].

[11] R. Kadyrov, D. Heller, R. Selke, Tetrahedron Asymmetry 9

(1998) 329.

[12] (a) D.L. Allen, V.C. Gibson, M.L.H. Green, J.F. Skinner, J.

Bashkin, P.D. Grebenik, J. Chem. Soc. Chem. Commun. (1983)

895;

(b) M.L.H. Green (British Petroleum Co. PLC), Eur. Pat. Appl.

EP 117156, 1984 [Chem. Abstr. 102 (1985) 6809].

[13] (a) C. Eckert, L. Dahlenburg, A. Wolski, Z. Naturforsch. B:

Chem. Sci. 50b (1995) 1004;

Acknowledgements

Financial support from the Deutsche Forschungsge-

meinschaft (Bonn) and the Fonds der Chemischen In-

dustrie (Frankfurt/Main) is gratefully acknowledged.

We are also indebted to Degussa-Hu¨ls AG (Hanau) for

a generous gift of platinum salts. Gas chromatographic

analyses were carried out at the Institut fu¨r Organische

Chemie, Universita¨t Regensburg. We gratefully ac-

knowledge the help of Professor Dr B. Ko¨nig and Dr

E. Eibler.

(b) L. Dahlenburg, V. Kurth, Eur. J. Inorg. Chem. (1998) 597;

(c) L. Dahlenburg, A. Kaunert, Acta Crystallogr, Sect. C: Cryst.

Struct. Commun. C 54 (1998) 1016;

(d) L. Dahlenburg, C. Becker, J. Ho¨ck, S. Mertel, J. Organomet.

Chem. 564 (1998) 155;

References

(e) L. Dahlenburg, A. Kaunert, Eur. J. Inorg. Chem. (1998) 885;

(f) L. Dahlenburg, C. Eckert, J. Organomet. Chem. 564 (1998)

227;

(g) L. Dahlenburg, Ger. Offen. DE 19732805, 1999 [Chem.

Abstr. 130 (1999) 168481];

[1] L. Dahlenburg, R. Go¨tz, J. Organomet. Chem. 619 (2001) 88.

[2] Review articles:(a) C. Botteghi, S. Paganelli, A. Schionato, M.

Marchetti, Chirality 3 (1991) 355;

(b) F. Agbossou, J.-F. Carpentier, A. Mortreux, Chem. Rev. 95

(1995) 2485;

(c) C.D. Frohning, C.W. Kohlpaintner, in: B. Cornils, W.A.

Herrmann (Eds.), Applied Homogeneous Catalysis with

Organometallic Compounds, VCH, Weinheim, 1996, Chapter

2.1.1;

(h) L. Dahlenburg, V. Kurth, J. Organomet. Chem. 585 (1999)

315.

[14] H. Brunner, S. Stefaniak, M. Zabel, Synthesis (1999) 1776.

[15] Application as ligands in conventional hydroformylation:

(a) S.-H. Kyung, Han’guk Nonghwa Hakhoechi 40 (1997) 588

[Chem. Abstr. 128 (1998) 154205];

(d) F. Ungva´ry, Coord. Chem. Rev. 188 (1999) 263.

[3] (a) C.U. Pittman, Jr., Y. Kawabata, L.I. Flowers, J. Chem. Soc.

Chem. Commun. (1982) 473;

(b) H. Urata, Y. Wada (Mitsubishi Chemical Industries Ltd.,

Japan), Jpn. Kokai Tokkyo Koho JP 09268152, 1997 [Chem.

Abstr. 127 (1997) 307164];

(c) H. Urata, Y. Wada (Mitsubishi Chemical Industries Ltd.,

Japan), PCT Int. Appl. WO 9843935, 1998 [Chem. Abstr. 129

(1998) 289879];

(b) G. Consiglio, P. Pino, L.I. Flowers, C.U. Pittman, J. Chem.

Soc. Chem. Commun. (1983) 612;

(c) G. Consiglio, S.C.A. Nefkens, A. Borer, Organometallics 10

(1991) 2046.

(d) H. Maas, R. Paciello, M. Ro¨per, J. Fischer, W. Siegel (BASF

A.-G., Germany), PCT Int. Appl. WO 9946044, 1999 [Chem.

Abstr. 131 (1999) 230267];

[4] (a) G. Parinello, J.K. Stille, J. Am. Chem. Soc. 109 (1987) 7122;

(b) J.K. Stille, H. Su, P. Brechot, G. Parinello, L.S. Hegedus,

Organometallics 10 (1991) 1183.

(e) D. Selent, K.-D. Wiese, D. Ro¨ttger, A. Bo¨rner, Angew.

Chem. 112 (2000) 1694; Angew. Chem. Int. Ed. 39 (2000) 1639.

[16] (a) T.V. RajanBabu, T.A. Ayers, Tetrahedron Lett. 35 (1994)

4295;

[5] (a) S. Csere´pi-Szu¨cs, J. Bakos, Chem. Commun. (1997) 635;

(b) S. Csere´pi-Szu¨cs, G. Huttner, L. Zsolnai, J. Bakos, J.

Organomet. Chem. 586 (1999) 70.

[6] (a) J.E. Babin, G.T. Whiteker (Union Carbide Chemicals and

Plastics Technology Corp.), PCT Int. Appl. WO 9303839, 1993

[Chem. Abstr. 119 (1993) 159872];

(b) X. Xu, H. Zhou, J. Chen, H. Fu, Fenzi Cuihua 11 (1997) 374

[Chem. Abstr. 128 (1998) 4864];

(c) R. Ewalds, E.B. Eggeling, A.C. Hewat, P.C.J. Kamer,

P.W.N.M. van Leeuwen, D. Vogt, Chem. Eur. J. 6 (2000) 1496.

[17] G.K. Anderson, H.C. Clark, J.A. Davies, Organometallics 1

(1982) 64.

[18] (a) R. Bardi, A.M. Piazzesi, G. Cavinato, P. Cavoli, L. Toniolo,

J. Organomet. Chem. 224 (1982) 407;

(b) J.E. Babin, G.T. Whiteker (Union Carbide Chemicals and

Plastics Technology Corp.), US 5360938, 1994 [Chem. Abstr.

122 (1995) 186609].

[7] (a) G.J.H. Buisman, E.J. Vos, P.C.J. Kamer, P.W.N.M. van

Leeuwen, J. Chem. Soc. Dalton Trans. (1995) 409;

(b) G.J.H. Buisman, L.A. van der Veen, A. Klootwjik, W.G.J.

de Lange, P.C.J. Kamer, P.W.N.M. van Leeuwen, D. Vogt,

Organometallics 16 (1997) 2929;

(b) R. Bardi, A.M. Piazzesi, A. del Pra, G. Cavinato, L. Toniolo,

J. Organomet. Chem. 234 (1982) 107;

(c) G. Cavinato, L. Toniolo, J. Organomet. Chem. 241 (1983)

275;

(c) S. Deerenberg, P.C.J. Kamer, P.W.N.M. van Leeuwen,

Organometallics 19 (2000) 2065.

(d) A. Scrivanti, A. Berton, L. Toniolo, C. Botteghi, J.

Organomet. Chem. 314 (1986) 369;

[8] (a) N. Sakai, S. Mano, K. Nozaki, H. Takaya, J. Am. Chem.

Soc. 115 (1993) 7033;

(b) T. Horiuchi, T. Ohta, E. Shirakawa, K. Nozaki, H. Takaya,

J. Org. Chem. 62 (1997) 4285;

(c) K. Nozaki, N. Sakai, T. Nanno, T. Higashijima, S. Mano, T.

Horiuchi, H. Takaya, J. Am. Chem. Soc. 119 (1997) 4413;

(d) K. Nozaki, Y. Itoi, F. Shibahara, E. Shirakawa, T. Ohta, H.

Takaya, T. Hiyama, J. Am. Chem. Soc. 120 (1998) 4051;

(e) H.J. Ruegg, P.S. Pregosin, A. Scrivanti, L. Toniolo, C.

Botteghi, J. Organomet. Chem. 316 (1986) 233;

(f) A. Scrivanti, C. Botteghi, L. Toniolo, A. Berton, J.

Organomet. Chem. 344 (1988) 261.

[19] M. Go´mez, G. Muller, D. Sainz, J. Sales, X. Solans,

Organometallics 10 (1991) 4036.

L. Dahlenburg, S. Mertel / Journal of Organometallic Chemistry 630 (2001) 221–243

243

[20] (a) I. To´th, T. Ke´gl, C.J. Elsevier, L. Kolla´r, Inorg. Chem. 33

(1994) 5798;

[37] (a) F. Bachechi, Acta Crystallogr. Sect. C Cryst. Struct. Com-

mun. C 49 (1993) 460;

(b) T. Ke´gl, L. Kolla´r, L. Radics, Inorg. Chim. Acta 265 (1997)

249;

(b) F. Bachechi, P. Mura, L. Zambonelli, Acta Crystallogr. Sect.

C Cryst. Struct. Commun., C 49 (1993) 2072;

(c) E. Farkas, L. Kolla´r, M. Moret, A. Sironi, Organometallics

15 (1996) 1345;

(c) A. Albinati, S. Chaloupka, J. Eckert, L.M. Venanzi, M.K.

Wolfer, Inorg. Chim. Acta 259 (1997) 305;

(d) T. Ke´gl, L. Kolla´r, J. Mol. Catal. A Chem. 122 (1997) 95.

[21] J.J. Mrowca (du Ponts de Nemours, E.I. and Co.), US 3876672,

1975 [Chem. Abstr. 84 (1976) 30432].

[22] S.C. Tang, L. Kim, J. Mol. Catal. 14 (1982) 231.

[23] (a) P.W.N.M. van Leeuwen, C.F. Roobeek (Shell Research

B.V.), Eur. Pat. Appl. EP 82576, 1983 [Chem. Abstr. 99 (1983)

121813];

(d) A. Albinati, G. Bracher, D. Carmona, J.H.P. Jans, W.T.

Klooster, T.F. Koetzle, A. Macchioni, J.S. Ricci, R. Thouvenot,

L.M. Venanzi, Inorg. Chim. Acta 265 (1997) 255 and references

cited therein.

[38] M. Gerisch, F.W. Heinemann, C. Bruhn, J. Scholz, D. Stein-

born, Organometallics 18 (1999) 564 and references cited therein.

[39] S.A. Litster, L. Mole, A.D. Redhouse, J.L. Spencer, Acta Crys-

tallogr. Sect. C Cryst. Struct. Commun. C 48 (1992) 913.

[40] P. Meessen, D. Vogt, W. Keim, J. Organomet. Chem. 551 (1998)

165.

(b) P.W.N.M. van Leeuwen, C.F. Roobeek, R.L. Wife, J.H.G.

Frijns, J. Chem. Soc. Chem. Commun. (1986) 31;

(c) P.W.N.M. van Leeuwen, C.F. Roobeek, J.H.G. Frijns, A.G.

Orpen, Organometallics 9 (1990) 1211;

(d) P.W.N.M. van Leeuwen, C.F. Roobeek, New J. Chem. 14

(1990) 487.

[41] (a) L. Kolla´r, J. Bakos, I. To´th, B. Heil, J. Organomet. Chem.

350 (1988) 277;

(b) L. Kollar, P. Sa´ndor, G. Szalontai, J. Mol. Catal. 67 (1991)

191;

(c) L. Kolla´r, T. Ke´gl, J. Bakos, J. Organomet. Chem. 453 (1993)

155;

[24] E. Paumard, A. Mortreux, F. Petit, J. Chem. Soc. Chem. Com-

mun. (1989) 1380.

[25] (a) C. Botteghi, S. Paganelli, U. Matteoli, A. Scrivanti, R.

Ciorciaro, L.M. Venanzi, Helv. Chim. Acta 73 (1990) 284;

(b) C. Botteghi, S. Paganelli, A. Perosa, R. Lazzaroni, G.

Uccello–Barretta, J. Organomet. Chem. 447 (1993) 153.

[26] R.L. Brainard, W.R. Nutt, T.R. Lee, G.M. Whitesides,

Organometallics 7 (1988) 2379.

[27] A. Appelt, V. Ariaratnam, A.C. Willis, S.B. Wild, Tetrahedron

Asymmetry 1 (1990) 9.

[28] (a) L. Mole, J.L. Spencer, N. Carr, A.G. Orpen, Organometallics

10 (1991) 49;

(b) N. Carr, L. Mole, A.G. Orpen, J.L. Spencer, J. Chem. Soc.

Dalton Trans. (1992) 2653.

[29] (a) P.J. Stang, Y.-H. Huang, J. Organomet. Chem. 431 (1992)

247;

(b) P.J. Stang, Z. Zhong, A.M. Arif, Organometallics 11 (1992)

1017.

[30] G.P.C.M. Dekker, A. Buijs, C.J. Elsevier, K. Vrieze, P.W.N.M.

van Leeuwen, W.J.J. Smeets, A.L. Spek, Y.F. Wang, C.H. Stam,

Organometallics 11 (1992) 1937.

(d) I. To´th, I. Guo, B.E. Hanson, Organometallics 12 (1993) 848;

(e) I. To´th, C.J. Elsevier, J.G. de Vries, J. Bakos, W.J.J. Smeets,

A.L. Spek, J. Organomet. Chem. 540 (1997) 15.

[42] (a) A. Scrivanti, S. Zeggio, V. Beghetto, U. Matteoli, J. Mol.

Catal. A Chem. 101 (1995) 217;

(b) A. Scrivanti, V. Beghetto, A. Bastianini, U. Matteoli, G.

Menchi, Organometallics 15 (1996) 4687.

[43] L. Kolla´r, G. Consiglio, P. Pino, J. Organomet. Chem. 300

(1987) 305.

[44] I. Schwager, J.F. Knifton, J. Catal. 45 (1976) 256.

[45] C.Y. Hsu, M. Orchin, J. Am. Chem. Soc. 97 (1975) 3553.

[46] F. Ozawa, T. Hikida, K. Haebe, T. Mori, Organometallics 17

(1998) 1018.

[47] E.V. van den Berghe, G.P. van der Kelen, J. Organomet. Chem.

6 (1966) 515.

[48] H.C. Clark, G. Ferguson, M.J. Hampden-Smith, H. Ru¨egger,

B.L. Ruhl, Can. J. Chem. 66 (1988) 3120.

[49] G. Cavinato, G. de Munno, M. Lami, M. Marchionna, L.

Toniolo, D. Viterbo, J. Organomet. Chem. 466 (1994) 277.

[50] A. Albinati, N. Naegeli, K.H.A. Ostoja Starzewski, P.S.

Pregosin, H. Ru¨egger, Inorg. Chim. Acta 76 (1983) L231–L232.

[51] R. van Asselt, E. Rijnberg, C.J. Elsevier, Organometallics 13

(1994) 706.

[31] B.L. Bennett, J. Birnbaum, D. Roddick, Polyhedron 14 (1995)

187.

[32] (a) G.S. Hill, L.M. Rendina, R.J. Puddephatt, J. Chem. Soc.

Dalton Trans. (1996) 1809;

(b) G.S. Hill, G.P.A. Yap, R.J. Puddephatt, Organometallics 18

(1999) 1408.

[33] (a) J. Chatt, L.M. Vallarino, L.M. Venanzi, J. Chem. Soc. (1957)

2496;

[52] A.C.T. North, D.C. Phillips, F.S. Mathews, Acta Crystallogr. A

24 (1968) 351.

[53] L.J. Farrugia, WinGX (Version 1.63.01) — An Integrated Sys-

tem of Windows Programs for the Solution, Reﬁnement, and

Analysis of Single Crystal X-ray Diffraction Data, University of

Glasgow, 1999; J. Appl. Crystallogr. 32 (1999) 837.

[54] A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi,

A.G.G. Moliterni, M.C. Burla, G. Polidori, M. Camalli, R.

Spagna, SIR-97 — A Package for Crystal Structure Solution

by Direct Methods and Reﬁnement, Bari, Rome, 1997.

[55] G.M. Sheldrick, SHELXL-97 — A Program for the Reﬁne-

ment of Crystal Structures from Diffraction Data (Release 97-2),

Universita¨t Go¨ttingen, 1997.

(b) H.C. Clark, L.E. Manzer, J. Organomet. Chem. 59 (1973)

411;

(c) J.X. McDermott, J.F. White, G.M. Whitesides, J. Am. Chem.

Soc. 98 (1976) 6521;

(d) R.L. Brainard, T.M. Miller, G.M. Whitesides, Organometal-

lics 5 (1986) 1481.

[34] (a) D.A. Redﬁeld, J.H. Nelson, L.W. Cary, Inorg. Nucl. Chem.

Lett. 10 (1974) 727;

(b) A.W. Verstuyft, J.H. Nelson, L.W. Cary, Inorg. Chem. 15

(1976) 732.

[35] P.S. Pregosin, R. Kunz, Helv. Chim. Acta 58 (1975) 423.

[36] G.K. Anderson, in: E.W. Abel, F.G.A. Stone, G. Wilkinson

(Eds.), Comprehensive Organometallic Chemistry II, Vol. 9 (R.J.

Puddephatt, Ed.), Pergamon Press, Oxford, 1995, Chapter 8.

[56] L.J. Farrugia, ORTEP-3 for Windows (Version 1.062), Univer-

sity of Glasgow, 1997/2000; J. Appl. Crystallogr. 30 (1997) 565.

[57] H.D. Flack, Acta Crystallogr. A 39 (1983) 876.

Article Doi

Chiral chelate phosphanes: XI. Application of cyclopentane-based C2 chiral bis(phosphane) ligands C5H8(PR2)2 to Pt-Sn-catalyzed styrene hydroformylation

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