Pyramidal stability of 16-electron half-sandwich intermediates [CpRu(P-P)]+ with P-P ligands forming four- to six-membered chelate rings

Article abstract of DOI:10.1021/om900830a

This paper reports the synthesis, isomer separation, and X-ray characterization of the compounds (S_Ru,Sc)-/(R_RU,Sc)- [CpRu(Chairphos)Cl], Chairphos = (S)-1,3-bis(diphenylphosphanyl)butane, and cis-/trans-[CpRu(Dppm-Me)Cl], Dppm-Me =

Full text of DOI:10.1021/om900830a

428 Organometallics 2010, 29, 428–435
DOI: 10.1021/om900830a
Pyramidal Stability of 16-Electron Half-Sandwich Intermediates
[CpRu(P-P)]þ with P-P Ligands Forming Four- to Six-Membered
Chelate Rings
Henri Brunner,*,† Manfred Muschiol,† Takashi Tsuno,*,‡ Takemoto Takahashi,‡ and
Manfred Zabel†,§
†
‡
Institut fu€r Anorganische Chemie, Universitat Regensburg, 93040 Regensburg, Germany and Department
€
of Applied Molecular Chemistry, College of Industrial Technology, Nihon University, Narashino,
Chiba 275-8575, Japan. §X-ray structure analyses.
Received September 25, 2009
This paper reports the synthesis, isomer separation, and X-ray characterization of the compounds
(SRu,SC)-/(RRu,SC)-[CpRu(Chairphos)Cl], Chairphos = (S)-1,3-bis(diphenylphosphanyl)butane,
and cis-/trans-[CpRu(Dppm-Me)Cl], Dppm-Me = 1,1-bis(diphenylphosphanyl)ethane. The Cl/I
exchange reactions proceeded with predominant retention of the metal configuration, accompanied
by some inversion, except for trans-[CpRu(Dppm-Me)Cl], which was stereospecifically converted to
trans-[CpRu(Dppm-Me)I]. Temperature-dependent kinetic measurements afforded rates and acti-
vation parameters of the Cl/I exchange and epimerization reactions that follow basilica-type energy
profiles. Dissociation of Cl- from [CpRu(Chairphos)Cl] and [CpRu(Dppm-Me)Cl] gives pyramidal
intermediates [CpRu(Chairphos)]þ and [CpRu(Dppm-Me)]þ, which maintain the metal configura-
tion. The 16-electron intermediates can react with excess I- to form the iodo complexes with retention
of the metal configuration, or they can change the metal configuration by pyramidal inversion,
leading to formation of iodo complexes with inverted metal configuration. The kinetic measurements
show that the pyramidal inversion via planar transition states depends on the P-Ru-P0 angles. It
increases with decreasing chelate ring size, because small P-Ru-P0 angles resist planarization in the
transition, which requires larger P-Ru-P0 angles.
Introduction
Scheme 2, the characteristic features of which are the pyr-
amidal intermediates [CpRu(Prophos)]þ, which invert only
slowly via planar transition states. The relatively small
P-Ru-P0 angles of 82-83° in the Ru(Prophos) system1,4
are supposed to resist pyramidal inversion, passing planar
transition states, for which P-Ru-P0 angles of 96° and 100°
seem to be best according to calculations.5-8
We wanted to approach the problem of the pyramidal
inversion of the species [CpRu(P-P0)]þ as a function of che-
late ring size, resulting in different P-Ru-P0 angles. In the
complex [CpRu(PPh2-CH2-CH2-CHMe-PPh2)Cl] ([CpRu-
(Chairphos)Cl]) (Scheme 3), characterized by a six-mem-
bered chelate ring, pyramidal inversion should be faster due
to a larger P-Ru-P0 angle in the planar transition state. For
compound [CpRu(PPh2-CHMe-PPh2)Cl] ([CpRu(Dppm-
Me)Cl]) (Scheme 3), with a four-membered chelate ring, a
Dissociation of Cl- ions from the 18-electron half-sand-
wich complexes [CpRu(P-P0)Cl] afþfords unsaturated 16-
electron intermediates [CpRu(P-P0)] . Does the 16-electron
species maintain its pyramidal structure with an empty site in
place of the dissociated Cl- ligand or does it rearrange
simultaneously to its formation or subsequently? Are the
16-electron species [CpRu(P-P0)]þ planar or pyramidal
(Scheme 1)?1,2 The alternative is of importance, including
enantioþselective catalysis,3 because an intermediate [CpRu-
(P-P0)] retains the configuration at the metal atom as long
as it is pyramidal, whereas it loses chirality at the metal atom
when it is planar or passes a planar transition state.
Recently, we published detailed mechanistic studies for
compound [CpRu(PPh2-CH2-CHMe-PPh2)Cl] ([CpRu-
(Prophos)Cl]), containing a five-membered chelate ring.1,2
Kinetic measurements of Cl/I exchange and epimerization
reactions resulted in the basilica-type2 energy profile of
(4) Morandini, F.; Consiglio, G.; Straub, B.; Ciani, G.; Sironi, A. J.
Chem. Soc., Dalton Trans. 1983, 2293–2298.
(5) Hofmann, P. Angew. Chem. 1977, 89, 551–553. Angew. Chem.,
Int. Ed. Engl. 1977, 16, 536-537.
*To whom correspondence should be addressed. (H.B.) Fax: þ49-
941-9434439. E-mail: henri.brunner@chemie.uni-regensburg.de. (T.T.)
Fax: þ81 47 474 2579. E-mail: tsuno.takashi@nihon-u.ac.jp.
(1) Brunner, H.; Muschiol, M.; Tsuno, T.; Takahashi, T.; Zabel, M.
Organometallics 2008, 27, 3514–3525.
(6) Ward, T. R.; Schafer, O.; Daul, D.; Hofmann, P. Organometallics
1997, 16, 3207–3215.
ꢀ
(7) Aneetha, H.; Jimenez-Tenorio, M.; Puerta, M. C.; Valerga, P.;
Sapunov, V. N.; Schmid, R.; Kirchner, K.; Mereiter, K. Organometallics
(2) Brunner, H.; Tsuno, T. Acc. Chem. Res. 2009, 42, 1501–1510.
(3) Brunner, H. Angew. Chem. 1999, 111, 1248–1263. Angew. Chem.,
Int. Ed. 1999, 38, 1194-1208.
2002, 21, 5334–5346.
(8) Kawano, M.; Kobayashi, Y.; Ozeki, T.; Fujita, M. J. Am. Chem.
Soc. 2006, 128, 6558–6559.
r
pubs.acs.org/Organometallics
Published on Web 12/29/2009
2009 American Chemical Society

Article
Organometallics, Vol. 29, No. 2, 2010 429
Scheme 1. Dissociation of Cl- from the Half-Sandwich Complex
configuration. Only one of them is shown in Figure 1 (right
side). The P-Ru-P0 angles in the two independent molecules
of (SRu,SC)-[CpRu(Chairphos)I] were 91.0° and 90.2°, similar
to the P-Ru-P0 angle in (RRu,SC)-[CpRu(Chairphos)Cl].
[CpRu(P-P0)Cl]a
We also obtained an X-ray analysis of a crystal of (SRu
,
RC)-[CpRu(Chairphos)I], prepared using the ligand (R)-Chair-
phos (Table 1). In its configurational series (SRu,RC)-[CpRu-
(Chairphos)I] is the less stable diastereomer, whereas (RRu
,
SC)-[CpRu(Chairphos)Cl] and (SRu,SC)-[CpRu(Chairphos)I]
are the more stable diastereomers in their configurational series.
In all three structures the six-membered chelate rings adopt
chair conformations, the Cp ligands and the methyl groups of
Chairphos being in equatorial position. The Cl and I substit-
uents are axial, respectively.
Cl/I Exchange. The Cl/I exchange in (RRu,SC)- and (SRu
,
SC)-[CpRu(Chairphos)Cl] with excess [Bu4N]I (eq 1) in
CDCl3/CH3OH (9:1) was carried out as described in detail
for (RRu,RC)- and (SRu,RC)-[CpRu(Prophos)Cl].1
a Is the resulting 16-electron intermediate [CpRu(P-P0)]þ pyramidal
½CpRuðChairphosÞClꢀ þ ½Bu4NꢀI f
or planar?
½CpRuðChairphosÞIꢀ þ ½Bu4NꢀCl
ð1Þ
retardation of the pyramidal inversion is expected, because
the small P-Ru-P0 angle in the transition state should
greatly resist planarization.
A sample of (RRu,SC)-/(SRu,SC)-[CpRu(Chairphos)Cl] =
76:24 and a 15- to 20-fold excess of [Bu4N]I were used in the Cl/
I exchange reaction. It was not necessary to add Cp2Co to get
sharp NMR signals.1 In the measurement at 300 K (Figure 2)
the concentration of (SRu,SC)-[CpRu(Chairphos)Cl] decre-
ased relatively fast, whereas the concentration of (RRu,SC)-
[CpRu(Chairphos)Cl] decreased only slowly, which means
that the (SRu,SC)-diastereomer reacted faster with [Bu4N]I
[CpRu(Chairphos)X], X = Cl, I
Synthesis and X-ray Analyses. [CpRu(Chairphos)Cl], the
properties of which are similar to [CpRu(Prophos)Cl], was
prepared from [CpRu(PPh3)2Cl] and (S)-Chairphos9 ((S)-
1,3-bis(diphenylphosphanyl)butane) (Scheme 4).
than the (RRu,SC)-diastereomer. Figure 2 shows that (SRu
,
SC)-[CpRu(Chairphos)Cl] is mainly converted to (RRu,SC)-
[CpRu(Chairphos)I] with retention of the metal configuration.
As the Cl/I exchange in (RRu,SC)-[CpRu(Chairphos)Cl], re-
sulting mainly in (SRu,SC)-[CpRu(Chairphos)I], contributes to
some extent, no quantitative conclusions concerning the share
of inversion of the metal configuration during the Cl/I ex-
change reactions can be drawn, which had been possible for
[CpRu(Prophos)Cl].1
In the synthesis the diastereomers were obtained in the
ratio (RRu,SC)/(SRu,SC) = 76:24. We used this diastereomer
mixture for the determination of the kinetics of the Cl/I
exchange and epimerization reactions. Two recrystalliza-
tions from dichloromethane/hexane gave a sample (RRu
SC)/(SRu,SC) = 95:5.
,
For X-ray analysis a crystal was taken from the sample
(RRu,SC)-/(SRu,SC)-[CpRu(Chairphos)Cl] = 95:5. There were
two independent molecules in the unit cell, differing in the
arrangement of the phenyl substituents (Table 1). Both had a
(RRu,SC)-configuration. Only one of them is shown in Figure 1
(left side). Interestingly, the P-Ru-P0 angles in the two
independent molecules of (RRu,SC)-[CpRu(Chairphos)Cl]
were 91.3° and 91.1° and thus much larger than the P-Ru-P0
angle in (SRu,RC)-[CpRu(Prophos)Cl], with 82.9°.4 Such an
enlargement was expected going from a five-membered to a
The first-order rate constant for the disappearance of (SRu
,
,
SC)-[CpRu(Chairphos)Cl] at 300 K was k=3.9 ꢁ 10-3 min-1
corresponding to a half-life of 177 min (Table2). To measure
the Cl/I exchange in (RRu,SC)-[CpRu(Chairphos)Cl] the sam-
ple of (RRu,SC)-/(SRu,SC)-[CpRu(Chairphos)Cl]=76:24, used
for the Cl/I exchange in (SRu,SC)-[CpRu(Chairphos)Cl], had
tobe kept and measuredat300K formuchlongertimes, asthe
Cl/I exchange of the less reactive diastereomer was much
slower (half-life 2200 min) than that of the more reactive
diastereomer (half-life 177 min).
six-membered chelate ring. There are three Cl HC hydrogen
3 3 3
˚
bonds of 2.81-2.83 A length. Two of them are intramolecular
to the axial CH of the CHMe group and an ortho-phenyl CH,
The rate constants of the Cl/I exchange in (RRu,SC)- and
(SRu,SC)-[CpRu(Chairphos)Cl] with [Bu4N]I increased with
rising temperature. Table 2 shows that the rate constants at
293-323 K for the disappearance of (RRu,SC)-[CpRu-
(Chairphos)Cl] in the Cl/I exchange are about 5-10 times
slower than for (SRu,SC)-[CpRu(Chairphos)Cl].
Epimerization. The epimerization of (RRu,SC)-/(SRu,SC)-
[CpRu(Chairphos)Cl] was studied in CDCl3/CH3OH =
9:1 (eq 2).
and one is intermolecular to a meta-phenyl CH.
A mixture of diastereomers (RRu,SC)-/(SRu,SC)-[CpRu-
(Chairphos)I] = 10:90 was obtained by reaction of (RRu
,
SC)-/(SRu,SC)-[CpRu(Chairphos)Cl] = 87:13 with NaI in
methanol. Recrystallization from acetone afforded an en-
richment of (RRu,SC)/(SRu,SC) = 6:94.
An X-ray analysis with a crystal taken from a sample of (RRu
,
SC)/(SRu,SC)-[CpRu(Chairphos)I] = 6:94 was carried out. As
for the chloro complex there were two independent molecules of
[CpRu(Chairphos)I] in the unit cell, differing in the arrange-
ment of the phenyl substituents. Both molecules had (SRu,SC)-
ðRRu,SCÞ-½CpRuðChairphosÞClꢀa
ðSRu,SCÞ-½CpRuðChairphosÞClꢀ
ð2Þ
A sample of (SRu,RC)/(RRu,RC)-[CpRu(Prophos)Cl] =
77:23 approached at 293 K the equilibrium composition
(9) Kagan, H. B.; Fiaud, J. C.; Hoornaert, C.; Meyer, D.; Poulin, J. C.
Bull. Soc. Chim. Belg. 1979, 88, 923–931.

430 Organometallics, Vol. 29, No. 2, 2010
Brunner et al.
Scheme 2. Energy Diagram of Cl/I Exchange and Epimerization of [CpRu(Prophos)Cl]
Scheme 3. Complexes [CpRu(P-P0)Cl] Containing Four-, Five-,
and Six-Membered Chelate Rings
favored the bimolecular back reaction of the intermediate
[CpRu(Prophos)]þ with Cl- to the starting material with
respect to pyramidal inversion (Scheme 2).1 Such a retarda-
tion was also expected for the epimerization of [CpRu-
(Chairphos)Cl] in the presence of excess [Bu4N]Cl. However,
the epimerization rates of [CpRu(Chairphos)Cl] in the pre-
sence and in the absence of [Bu4N]Cl turned out to be the
same (Table 3). This is due, at least in part, to the low barrier
of pyramidal inversion. It may also be due to the fact that
the dissociation of Cl- is 2-5 times slower in [CpRu-
(Chairphos)Cl] than in [CpRu(Prophos)Cl], which may in-
crease the barrier for the back reaction of the intermediate
[CpRu(Chairphos)]þ with Cl-.
Scheme 4. Diastereomers of [CpRu(Chairphos)X], X = Cl, Ia
0
Compared to the rates k1 and k1 of the Cl/I exchange
reactions, the rates kf and kr for the forward and back-
ward reactions in the epimerization are about 3 times
slower, because in the epimerization reaction the inter-
mediates (RRu,SC)- and (SRu,SC)-[CpRu(Chairphos)]þ
have to cross another barrier in the basilica-type energy
profile of Scheme 2. The same trend is observed in the
ΔGq values for Cl/I exchange and epimerization in Tables 2
and 3.
a The priority sequence of the ligands in [CpRu(Chairphos)Cl] is
Cp > Cl > PCHMe > PCH2, whereas in [CpRu(Chairphos)I] it is I >
Cp > PCHMe > PCH2, which leads to different configurational
symbols for the same relative configurations.10,11
[CpRu(Dppm-Me)X], X = Cl, I
(RRu,SC)-/(SRu,SC)-[CpRu(Prophos)Cl] = 91:9 with kep =
6.3 ꢁ 10-4 (min-1), corresponding to a half-life τ1/2 = 18 h
To form a four-membered chelate ring in compounds of
the type [CpRu(P-P)X] we choose the ligand 1,1-bis-
(diphenylphosphanyl)ethane (Dppm-Me).12 The complexes
[CpRu(Dppm-Me)X] (Scheme 5) are achiral, because they
(Table 3). Using the equilibrium constant K = 10.3 the rate
constants kf and kr for the forward reaction (RRu,SC) f(SRu,
SC) and the backward reaction (SRu,SC) f (RRu,SC) could be
calculated. Table 2 shows the temperature dependence of the
rate constants of the epimerization reaction. At 293 K the half-
life for approach to equilibrium was down to 34 min.
The epimerization of [CpRu(Prophos)Cl] had been re-
tarded in the presence of [Bu4N]Cl, because excess Cl- had
(10) Cahn, R. S.; Ingold, C.; Prelog, V. Angew. Chem. 1966, 78, 413–
447. Angew. Chem., Int. Ed. Engl. 1966, 5, 385-415.
(11) Brunner, H. Enantiomer 1997, 2, 133–134.
(12) Hogarth, G.; Kilmartin, J. J. Organomet. Chem. 2007, 692, 5655–
5670.

Article
Organometallics, Vol. 29, No. 2, 2010 431
Table 1. Crystallographic Data for [CpRu(Chairphos)Hal] and [CpRu(Dppm-Me)Hal] Complexes
(RRu,SC)-[CpRu-
(Chairphos)Cl]
(SRu,SC)-[CpRu-
(Chairphos)I]
(SRu,RC)-[CpRu-
(Chairphos)I]
cis-[CpRu-
(Dppm-Me)Cl]
trans-[CpRu-
(Dppm-Me)I]
cis-[CpRu-
(Dppm-Me)I]
empirical formula
fw
cryst syst
C33H33ClP2Ru
628.05
monoclinic
P21
9.4176(2)
15.3229(3)
19.8384(4)
90
99.227(2)
90
2825.74(10)
4
1.476
6.581
semiempirical
C33H33IP2Ru
719.50
monoclinic
P21
19.9397(14)
15.6337(11)
9.4492(6)
90
100.283(8)
90
C33H33IP2Ru
719.50
monoclinic
P21
9.44810(10)
15.69280(10)
20.0147(2)
90
100.2820(10)
90
C31H29ClP2Ru
600.00
monoclinic
P21
9.8103(1)
14.1330(1)
10.4642(1)
90
114.253(1)
90
C31H29IP2Ru
691.45
monoclinic
P1
9.4185(5)
9.5250(4)
15.8005(7)
78.325(4)
88.954(4)
76.134(4)
1347.02(11)
2
1.705
14.961
semiempirical
1.00000-0.31353
684
C31H29IP2Ru
691.45
monoclinic
P21/n
15.9366(2)
11.0595(1)
17.0208(2)
90
111.178(1)
90
space group
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A)
Z
2898.3(3)
4
1.649
2919.87(5)
4
1.637
1322.80(2)
2
1.506
2797.32(6)
4
1.642
F calcd (Mg/m3)
abs coeff (mm-1
abs correct
transmn max./min. 1.00000/0.61915
)
1.738
13.829
7.001
14.409
analytical
0.8243/0.7128
1432
semiempirical
1.00000/0.36683
1432
semiempirical
1.00000-0.57393
612
semiempirical
1.00000-0.12978
1368
F(000)
cryst size (mm)
θ range (deg)
1288
0.22 ꢁ 0.19 ꢁ 0.10 0.12 ꢁ 0.09 ꢁ 0.04 0.21 ꢁ 0.13 ꢁ 0.08 0.10 ꢁ 0.06 ꢁ 0.05 0.24 ꢁ 0.05 ꢁ 0.02 0.13 ꢁ 0.07 ꢁ 0.02
2.26-66.44
(Cu KR)
22 037/9598
0.0443
9598/667
1.039
2.59-26.91
(Mo KR)
30 381/11955
0.0310
11 955/667
0.904
0.0303/0.0607
0.0389/0.0620
-0.023(17)
1.211/-0.409
2.24-66.58
(Cu KR)
12 141/7659
0.0308
7659/667
4.63-66.56
(Cu KR)
10 311/4347
0.0279
4347/317
2.86-66.76
(Cu KR)
13 547/4620
0.0347
4620/316
1.013
0.0297/0.0747
0.0361/0.774
3.26-66.56
(Cu KR)
21 671/4893
0.0316
4893/317
0.999
0.0211/0.0503
0.0240/0.0513
rflns/unique
Rint
data/params
goodness of fit F2
1.004
1.051
R1/wR2 (I > 2σ(I)) 0.0423/0.1039
0.0330/0.0838
0.0356/0.0854
-0.004(5)
0.877/-0.679
0.0209/0.0498
0.0221/0.0501
-0.008(6)
0.384/-0.266
R1/wR2 (all data)
abs struct param
largest diff peak
0.0539/0.1093
0.000(12)
1.105/-0.617
0.814/-0.713
0.338/-0.608
-3
˚
and hole (e A
CCDC no.
)
748186
748187
748191
748188
748189
748190
Figure 1. Molecular structures of (RRu,SC)-[CpRu(Chairphos)Cl] and (SRu,SC)-[CpRu(Chairphos)I]. Only one of the two indepen-
dent molecules in the unit cell is shown, respectively.
contain a plane of symmetry. However, cis-/trans-isomers
are possible. We use the designations cis/trans for the
compounds [CpRu(Dppm-Me)Cl] referring to the four-
membered Ru-P-C-P chelate ring as defined in Scheme 5.
After dissociation of Cl- from the complexes [CpRu-
(dppm-Me)Cl] pyramidal inversion interchanges the fragments
cis- and trans-[CpRu(Dppm-Me)]þ. Thus, pyramidal inversion
corresponds to a geometrical cis-/trans-isomerization. On the
other hand, pyramidal inversion of the fragments [CpRu-
(Prophos)]þ and [CpRu(Chairphos)]þ, obtained on dissocia-
tion of Cl- from the complexes [CpRu(Prophos)Cl] and
[CpRu(Chairphos)Cl], had inverted the metal configuration
(see above).
[CpRu(Meotpm)Cl] (Meotpm = 1,1-bis(di-o-tolylphospha-
nyl)ethane) were not separated.13 cis-Stereochemistry was
established for [Cp*Ru(PPh2-CHCN-PPh2)Cl] by X-ray
analysis.14
The chloro complexes cis- and trans-[CpRu(Dppm-
Me)Cl] could be converted to the iodo complexes cis- and
trans-[CpRu(Dppm-Me)I] with KI in methanol. Taking into
account the different tendencies of the cleavage of the Ru-Cl
bond in cis- and trans-[CpRu(Dppm-Me)Cl], the Cl/I sub-
stitution was carried out for cis-[CpRu(Dppm-Me)Cl] at
reflux and for trans-[CpRu(Dppm-Me)Cl] at room tempera-
ture. The cis-/trans-isomers in both the Cl and I series can
easily be differentiated on the basis of their 31P NMR signals.
All the compounds show the molecular ions in the EI mass
spectra.
Synthesis and X-ray Analyses. Reaction of Dppm-Me with
[CpRu(PPh3)2Cl] in refluxing toluene afforded a 74:26 mix-
ture of cis-/trans-[CpRu(Dppm-Me)Cl]. Separation of the
cis-/trans-isomers can be achieved by silica gel chroma-
tography with ether/hexane. The cis-/trans-isomers of
X-ray structure analyses have been carried out with cis-
[CpRu(Dppm-Me)Cl], cis-[CpRu(Dppm-Me)I], and trans-
[CpRu(Dppm-Me)I] (Figure 3, Table 1). A comparison is
€
(14) Braun, L.; Liptau, P.; Kehr, G.; Ugolotti, J.; Frohlich, R.; Erker,
G. Dalton Trans. 2007, 1409–1415.
(13) Filby, M.; Deeming, A. J.; Hogarth, G.; Lee, M.-Y. Can. J.
Chem. 2006, 84, 319–329.

432 Organometallics, Vol. 29, No. 2, 2010
Brunner et al.
CH3OH (9:1) (eq 3).
½CpRuðDppm-MeÞClꢀ þ ½Bu4NꢀI f
½CpRuðDppm-MeÞIꢀ þ ½Bu4NꢀCl
ð3Þ
Surprisingly, the differences in rate and stereoselectivity
were huge. Cl/I substitution in trans-[CpRu(Dppm-Me)Cl]
was fast, and the only substitution product was trans-[CpRu-
(dppm-Me)I]. At -20 °C the half-life of the first-order
reaction was 12 min. Conversely, Cl/I exchange in cis-
[CpRu(Dppm-Me)Cl] was slow, and cis- and trans-[CpRu-
(Dppm-Me)I] were observed as substitution products. As a
sample was used with a cis-/trans-ratio of 97:3, the small
amount of trans-[CpRu(Dppm-Me)Cl] was converted to
trans-[CpRu(Dppm-Me)I] in a fast reaction. As at 55 °C
the cis-/trans-isomerization of [CpRu(Dppm-Me)I] (see
below) is faster than the Cl/I substitution in cis-[CpRu-
(Dppm-Me)Cl] and the equilibrium constant K for the cis-/
trans-isomerization of [CpRu(Dppm-Me)I] is 33, the
amount of trans-[CpRu(Dppm-Me)I] did not exceed a few
percent during the Cl/I exchange reaction in cis-[CpRu-
(Dppm-Me)Cl]. At 60 °C the half-life of the disappearance
of cis-[CpRu(Dppm-Me)Cl] was still 450 min. Temperature-
dependent measurements (Table 4) allowed to determine the
activation parameters. Both activation entropies are nega-
Figure 2. Cl/I exchange reaction in (RRu,SC)-/(SRu,SC)-[CpRu-
(Chairphos)Cl] = 76:24 (b/9; 10.3 mmol L-1) with [Bu4N]I
(0.16 mol L-1) in CDCl3/CH3OH (9:1, v/v) at 300 K. The
products are (SRu,SC)-[CpRu(Chairphos)I] (O) and (RRu
SC)-[CpRu(Chairphos)I] (2).
,
tive, similar to the Cl/I exchange in (RRu,RC)- and (SRu
RC)-[CpRu(Prophos)Cl].1
,
Table 2. Kinetics of the Disappearance of (SRu,SC)- and (RRu,
SC)-[CpRu(Chairphos)Cl] in the Cl/I Exchange Reaction with
Excess [Bu4N]I in CDCl3/MeOH (9:1,v/v) and Activation Para-
meters
In the Cl/I exchange reaction in trans-[CpRu(Dppm-Me)Cl]
there was no cis-/trans-isomerization, another indication of
the high configurational stability of the fragment trans-[CpRu-
(Dppm-Me)]þ toward pyramidal inversion. The cis-/trans-iso-
merization, observed in the Cl/I substitution of cis-[CpRu-
(Dppm-Me)Cl], might be due, at least in part, to the
epimerization of the product [CpRu(Dppm-Me)I] (see below).
cis-/trans-Isomerization. It was not possible to measure the
interconversion of cis- and trans-[CpRu(Dppm-Me)Cl] ac-
curately. Keeping a solution of trans-[CpRu(Dppm-Me)Cl]
in CDCl3/CH3OH (9:1) at 40 °C the color changed from
yellow-orange to dark green. The signals of cis-[CpRu-
(Dppm-Me)Cl] appeared in the 31P NMR spectrum and also
signals of decomposition products. Unfortunately, all the
signals broadened appreciably. Equilibrium could not be
reached. Similar observations were made with solutions of
cis-[CpRu(Dppm-Me)Cl].
0
temp
(K)
k1 or k1
(min-1
τ1/2
(min)
reaction
)
(SRu,SC)-[CpRu(Chairphos)Cl] f
(RRu,SC)-[CpRu(Chairphos)I]
293
300
313
323
1.4 ꢁ 10-3
3.9 ꢁ 10-3
1.4 ꢁ 10-2
3.7 ꢁ 10-2
510
177
50
19
activation enthalpy ΔHq(300 K) = 83 kJ mol-1
activation entropy ΔSq(300 K) = -51 J mol-1 K-1
Gibbs free energy ΔGq(300 K) = 98 kJ mol-1
(RRu,SC)-[CpRu(Chairphos)Cl] f
(SRu,SC)-[CpRu(Chairphos)I]
293
300
313
323
1.6 ꢁ 10-4
3.2 ꢁ 10-4
2.0 ꢁ 10-3
6.4 ꢁ 10-3
4300
2200
350
110
activation enthalpy ΔHq(300 K) = 96 kJ mol-1
activation entropy ΔSq(300 K) = -25 J mol-1 K-1
Gibbs free energy ΔGq(300 K) = 103 kJ mol-1
It was possible to measure the cis-/trans-isomerization of
trans-[CpRu(Dppm-Me)I] in CDCl3/CH3OH (9:1) (eq 4).
appropriate for the two cis- and trans-isomers of [CpRu-
(Dppm-Me)I], in particular with respect to the four-mem-
bered P-Ru-P-C chelate ring. In both isomers the Ru-
P-C-P ring is nonplanar, bending toward the Cp ring. The
dihedral angles P-Ru-P-C are -11.60° for the cis-isomer
and -14.38° for the trans-isomer.
trans-½CpRuðDppm-MeÞIꢀacis-½CpRuðDppm-MeÞIꢀ
ð4Þ
Contrary to the cis-/trans-isomers of the iodo compound,
in the chloro complex cis-[CpRu(Dppm-Me)Cl] the four-
membered chelate ring bends away from the Cp ligand and
inclines toward the Cl ligand, as evident from the dihedral
angle P-Ru-P-C of 20.64°. This is supported by a
During the epimerization the signals of trans-[CpRu-
(Dppm-Me)I] almost disappeared for the benefit of the
signals of cis-[CpRu(dppm-Me)I], as the equilibrium lies
far on the side of cis-[CpRu(Dppm-Me)I]. For the isomeri-
zation of trans-[CpRu(Dppm-Me)I] in CDCl3/CH3OH (9:1)
the rate for approach to equilibrium at 55 °C was 3.7 ꢁ 10-3
min-1, corresponding to a half-life of τ1/2 =190 min. The
equilibrium constant K for the cis-/trans-ratio was 33, in-
dicating a cis-/trans-ratio of 97:3.
˚
Cl HC hydrogen bond (H-Cl distance 2.79 A). Further-
3 3 3
more, different from the iodo compounds, in cis-[CpRu-
(Dppm-Me)Cl] the four-membered ring is compressed along
the Ru-C axis. The compression is evident from the Ru
˚
distance of 3.06 A to the para-C atom in the chelate ring. In
cis- and trans-[CpRu(Dppm-Me)I] the distances from Ru to
˚
the para-C atom are 3.12 and 3.14 A.
Discussion
Cl/I Exchange. The Cl/I exchange in trans- and cis-[CpRu-
(Dppm-Me)Cl] with excess [Bu4N]I was measured in CDCl3/
In solution the Ru-Cl bond of the compounds
[CpRu(Chairphos)Cl] and [CpRu(Dppm-Me)Cl] tends to

Article
Organometallics, Vol. 29, No. 2, 2010 433
Table 3. Kinetics of the Epimerization of (RRu,SC)-/(SRu,SC)-[CpRu(Chairphos)Cl] in CDCl3/CH3OH (9:1, v/v) and Activation
Parameters
starting ratio
(RRu,SC): (SRu,SC)
equilibrium ratio
(RRu,SC): (SRu,SC)
temp (K)
K
kep (min-1
)
τ
1/2 (h)
kf (min-1
)
kr (min-1
)
77.1:22.9
76.2:23.8
76.4:23.6
76.4:23.6a
77.2:22.8
293
300
313
313
323
91.1:8.9
90.5:9.5
91.6:8.4
91.6:8.4
90.5:9.5
10.3
9.5
10.9
10.9
9.5
6.3 ꢁ 10-4
1.7 ꢁ 10-3
5.5 ꢁ 10-3
5.6 ꢁ 10-3
2.0 ꢁ 10-2
18
6.8
2.1
2.1
0.57
5.7 ꢁ 10-4
1.5 ꢁ 10-3
4.7 ꢁ 10-3
5.1 ꢁ 10-3
1.8 ꢁ 10-2
5.6 ꢁ 10-5
1.6 ꢁ 10-4
5.1 ꢁ 10-4
5.1 ꢁ 10-4
1.9 ꢁ 10-3
activation enthalpy ΔHqf(300 K) = 85 kJ mol-1
activation entropy ΔSqf(300 K) = -68 J mol-1 K-1
Gibbs free energy ΔGqf(300 K) = 105 kJ mol-1
ΔHqr(300 K) = 85 kJ mol-1
ΔSqr(300 K) = -50 J mol-1 K-1
ΔGqr(300 K) = 100 kJ mol-1
a Addition of a 25-fold excess of [Bu4N]Cl.
Figure 3. Molecular structures of cis-[CpRu(Dppm-Me)Cl] and trans-[CpRu(Dppm-Me)I].
Scheme 5. cis-/trans-Isomers [CpRu(Dppm-Me)X], X = Cl, Ia
trans-diastereomers reacted faster than the more stable (RRu
,
SC)- and cis-diastereomers. The activation parameters were
similar to those of the Cl/I exchange in [CpRu(Prophos)Cl],
including the strongly negative activation entropies dis-
cussed in ref 1. The rates of the Cl/I exchange in both
diastereomers of [CpRu(Chairphos)Cl] were slower by a
factor of 2-5 compared to [CpRu(Prophos)Cl], whereas in
trans-[CpRu(Dppm-Me)Cl] the Cl/I exchange already oc-
curred at 230-250 K.
The Cl/I exchange reaction in (RRu,RC)-[CpRu(Pro-
phos)Cl] had occurred with predominant retention of the
metal configuration, accompanied, however, by about 10%
inversion due to pyramidal inversion of the intermediate
(RRu,RC)-[CpRu(Prophos)]þ.1 Similarly, the unsaturated
intermediates [CpRu(Chairphos)]þ and [CpRu(Dppm-
Me)]þ, formed in the Cl- dissociation reactions, maintain
their pyramidal geometry. They can react with excess I- with
a A compound [CpRu(Dppm-Me)Cl] with Me and Cp trans to each
other is called Me-trans-to-Cp = trans and with Me and Cp cis to each
other Me-cis-to-Cp = cis.
dissociate according to þeq 5, forming the 16-electron inter-
mediates [CpRu(P-P0)] and a chloride ion, as reported for
[CpRu(Prophos)Cl].1 The cleavage of the Ru-Cl bonds,
reactions with first-order kinetics, are the rate-determining
steps in energy profiles similar to Scheme 2. The dissociation
of the Ru-Cl bond occurs in polar media such as metha-
nol and chloroform at room temperature or somewhat
above/below.
0
retention of the metal configuration (k2 and k2 paths) or
change the metal configuration by pyramidal inversion (k3
0
and k3 paths) in basilica-type energy profiles, as in Scheme 2.
All the Cl/I exchange reactions occurred with predominant
retention of configuration at the metal atom, in the reactions
of (SRu,SC)-, (RRu,SC)-[CpRu(Chairphos)Cl] and cis-[Cp-
Ru(Dppm-Me)Cl] accompanied by some inversion, due
to the competition of the intermediates for reaction with
excess I- and pyramidal inversion. trans-[CpRu(Dppm-
Me)Cl] could be converted stereospecifically to trans-[CpRu-
(Dppm-Me)I], indicating the high stability of the intermedi-
ate trans-[CpRu(Dppm-Me)]þ toward pyramidal inversion.
The rate of epimerization of (RRu,SC)- and (SRu,SC)-
[CpRu(Chairphos)Cl] is faster by a factor of 2-3 than that
½CpRuðP-P0ÞClꢀ f ½CpRuðP-P0Þꢀþ þ Cl-
ð5Þ
The Cl/I substitution in (SRu,SC)-/(RRu,SC)-[CpRu-
(Chairphos)Cl] and cis-/trans-[CpRu(Dppm-Me)Cl] resem-
bles that in (RRu,RC)-/(SRu,RC)-[CpRu(Prophos)Cl].1 Un-
saturated intermediates [CpRu(Chairphos)]þ and [CpRu-
(Dppm-Me)]þ are formed, which are quenched with ex-
cess I-. The thermodynamically less stable (SRu,SC)- and

434 Organometallics, Vol. 29, No. 2, 2010
Brunner et al.
Table 4. Kinetics of the Disappearance of trans- and cis-[CpRu(Dppm-Me)Cl] in the Cl/I Exchange Reaction with [Bu4N]I in CDCl3/
MeOH (9:1, v/v) and Activation Parametersa
-1
0
reaction
temp (K)
k1 or k1 (min
)
τ1/2 (min)
trans-[CpRu(Dppm-Me)Cl] f trans-[CpRu(Dppm-Me)I]
230
238
253
2.22 ꢁ 10-2
3.44 ꢁ 10-2
5.61 ꢁ 10-2
31
20
12
activation enthalpy ΔHq(300 K) = 17 kJ mol-1
activation entropy ΔS q(300 K) = -235 J mol-1 K-1
Gibbs free energy ΔGq(300 K) = 87 kJ mol-1
cis-[CpRu(Dppm-Me)Cl] f cis-/trans-[CpRu(Dppm-Me)I]
318
323
328
333
3.0 ꢁ 10-4
6.2 ꢁ 10-4
1.4 ꢁ 10-3
1.6 ꢁ 10-3
2300
1100
510
450
activation enthalpy ΔHq(300 K) = 97 kJ mol-1
activation entropy ΔSq(300 K) = -39 J mol-1 K-1
Gibbs free energy ΔGq(300 K) = 109 kJ mol-1
a For the kinetic measurements the integrals of the cyclopentadienyl protons in the 1H NMR spectra were used.
of (SRu,RC)- and (RRu,RC)-[CpRu(Prophos)Cl].1 This was to
be expected due to the larger P-Ru-P0 angles possible in the
transition state of the pyramidal inversion of (SRu,RC)- and
(RRu,RC)-[CpRu(Chairphos)]þ with the six-membered che-
late rings compared to (SRu,RC)- and (RRu,RC)-[CpRu-
(Prophos)]þ with the five-membered chelate rings.
0.097, CH2Cl2). Anal. Calcd for C33H33ClP2Ru (628.1): C,
63.10; H, 5.30. Found: C, 63.08; H, 5.24.
(RRu,SC)-/(SRu,SC)-(η5-Cyclopentadienyl)[1,3-bis(diphenyl-
phosphanyl)butane-KP)]iodoruthenium(II), (RRu,SC)- and (SRu
,
SC)-[CpRu(Chairphos)I]. A diastereomer mixture of (RRu,SC)-/
(SRu,SC)-[CpRu(Chairphos)Cl] = 13:87 (171 mg, 0.27 mmol)
was dissolved in methanol (30 mL), and NaI (2.84 g, 19 mmol)
was added. The mixture was stirred for 3 h at 70 °C. After
evaporation of the solvent, the residue was filtered with Celite
using dichloromethane. Evaporation of the solvents left a
residue, which was dissolved in a small amount of dichloro-
methane. Then hexane was added to the solution to deposit a
mixture of (RRu,SC)-/(SRu,SC)-[CpRu(Chairphos)I] = 10:90 as
orange crystals. Yield: 83% (162 mg, 0.23 mmol). Recrystalliza-
tion from acetone gave a diastereomer mixture of (RRu,SC)-/
(SRu,SC)-[CpRu(Chairphos)I] = 6:94.
Experimental Section15
(RRu,SC)-/(SRu,SC)-Chloro(η5-cyclopentadienyl)[1,3-bis(di-
phenylphosphanyl)butane-KP)]ruthenium(II), (RRu,SC)- and
(SRu,SC)-[CpRu(Chairphos)Cl]. [CpRu(PPh3)2Cl] (964 mg, 1.32
mmol) was added to a benzene solution (10 mL) of (S)-Chair-
phos9 (565 mg, 1.32 mmol), which was prepared according to
Kagan’s method using (R)-1,3-butanediol. The mixture was
refluxed for 10 h under exclusion of air. After evaporation of
the solvent the orange residue was chromatographed on silica
gel using ether/hexane (1:4) as an eluent. Yield: 39% (323 mg,
0.51 mmol) of (RRu,SC)-/(SRu,SC)-[CpRu(Chairphos)Cl] =
74:26 (determined by 31P{1H} NMR) as orange crystals. Two
recrystallizations from dichloromethane/hexane gave a diaster-
eomer mixture of (RRu,SC)-/(SRu,SC)-[CpRu(Chairphos)Cl] =
95:5.
1H NMR (CDCl3, 400 MHz, 293 K; major diastereomer
(SRu,SC)-[CpRu(Chairphos)I], signals of the minor diastereo-
mer (RRu,SC)-[CpRu(Chairphos)I] given in brackets if distin-
guishable): δ 7.88-7.82 (m, 2H, Ar-H), [7.98-7.92 (m, 2H, Ar-
H)], 7.59 (dt, 3JP-H = 1.5 Hz, 3JH-H = 7.8 Hz, 2H, Ar-H), [7.48
(br t, 3JH-H=8.4 Hz, 2H, Ar-H)], 7.48-7.00 (m, 16H, Ar-H),
4.38 (s, 5H, Cp-H), [4.43 (s, 5H, Cp-H)], 3.58-3.48 (m, 1H, CH),
3.06-2.85 (m, 2H, CH2), [3.32-3.22 (m, 2H, CH2)], 2.14-1.91
(m, 1H, CH), 1.72-1.52 (m, 1H, CH), 0.97 (dd, 3JP-H=10.6 Hz,
1H NMR (CDCl3, 400 MHz, 293 K; major diastereomer
(RRu,SC)-[CpRu(Chairphos)Cl], signals of the minor diastereo-
mer (SRu,SC)-[CpRu(Chairphos)Cl] given in brackets if distin-
guishable): δ 7.82-7.78 (m, 1H, Ar-H), [7.94-7.89 (m, 1H, Ar-
H)], 7.64 (t, 3JH-H=8.4 Hz, 1H, Ar-H), [7.53 (t, 3JH-H=8.4 Hz,
1H, Ar-H)], 7.39-7.01 (m, 18H, Ar-H), 4.28 (s, 5H, Cp-H), [4.34
(s, 5H, Cp-H)], 3.33-3.24 (m, 1H, CH), [3.20-3.11 (m, 1H,
3
3
3JH-H =7.1 Hz, CH3), [1.20 (dd, JP-H = 14.2 Hz, JH-H
=
7.6 Hz, CH3)]. 31P{1H} NMR (CDCl3, 162 MHz, 293 K; major
diastereomer (SRu,SC)-[CpRu(Chairphos)I], signals of the min-
or diastereomer (RRu,SC)-[CpRu(Chairphos)I] given in brac-
kets): δ 50.23 (d, 2JP-P=55.8 Hz, 1P), [41.52 (d, 2JP-P=61.8 Hz,
1P)], 35.11 (d, 2JP-P=55.8 Hz, 1P), [37.71 (d, 2JP-P=61.4 Hz,
1P)]. MS(ES): m/z (%)=720 (M, 100), 593 (M - I, 14). CD
(3.25 ꢁ 10-4 mol L-1, CH2Cl2): λmax (nm) 430 (Δε=39.7), 373
(Δε = 19.8). [R]2D6 = þ36.4 (c 0.094, CH2Cl2). Anal. Calcd for
C33H33IP2Ru (719.54): C, 55.08; H, 4.62. Found: C, 55.08; H,
4.61.
2
CH)], 2.73-2.53 (m, 2H, CH2), 1.97 (dd, JP-H = 33.6 Hz,
2JH-H =13.2 Hz, CH), 1.70-1.54 (m, 1H, CH), 1.00 (dd,
3
3
3JP-H =10.4 Hz, JH-H = 7.4 Hz, CH3), [1.09 (dd, JP-H
=
13.8 Hz, JH-H =7.3 Hz, CH3)]. 31P{1H} NMR (CDCl3, 162
MHz, 293 K; major diastereomer (RRu,SC)-[CpRu(Chair-
phos)Cl], signals of the minor diastereomer (SRu,SC)-[CpRu-
(Chairphos)Cl] given in brackets): δ 52.71 (d, 2JP-P = 59.5 Hz,
1P), [46.35 (d, 2JP-P = 61.4 Hz, 1P)], 40.00 (d, 2JP-P = 59.5 Hz,
1P), [38.51 (d, 2JP-P = 61.4 Hz, 1P)]. MS(ES): m/z (%) = 628
(M, 25), 593 (M - Cl, 100). CD (3.09 ꢁ 10-4 mol L-1, CH2Cl2):
3
cis-/trans-Chloro(η5-cyclopentadienyl)[1,1-bis(diphenylphos-
phanyl)ethane-KP)]ruthenium(II), cis-/trans-[CpRu(Dppm-Me)-
Cl]. [CpRu(PPh3)2Cl] (724 mg, 0.992 mmol) was added to a
toluene solution (20 mL) of 1,1-bis(diphenylphosphanyl)-
ethane12 (Dppm-Me, 620 mg 1.03 mmol). The mixture was
refluxed for 12 h under exclusion of air. After evaporation of
the solvent the orange residue was chromatographed on a short
silica gel column using ether/hexane (1:4) as an eluent to give
λ
max (nm) 416 (Δε = 57.2), 333 (Δε = -39.5). [R]2D6 = þ44.2 (c
(15) General: See ref 1.

Article
Organometallics, Vol. 29, No. 2, 2010 435
a mixture of diastereomers (462 mg, 78%, trans:cis = 26:74).
About 100 mg of this mixture was subjected to chromatography
on a silica gel column of 40 cm length using ether/hexane (3:7).
The two diastereomers readily separated. trans-[CpRu(Dppm-
Me)Cl] was obtained from the first fraction as yellow crystals.
Recrystallization of trans-[CpRu(Dppm-Me)Cl] from CH2Cl2/
ether/hexane afforded fine needles. The second fraction gave
cis-[CpRu(Dppm-Me)Cl] as orange crystals. Recrystallization
of cis-[CpRu(Dppm-Me)Cl] from acetone afforded orange-red
prisms suitable for X-ray crystallography.
(Dppm-Me)I] (95 mg, 79%) as orange prisms suitable for X-ray
analysis.
1H NMR (CDCl3, 400 MHz, 293 K): δ 7.63-7.57 (m, 4H, Ar-
3
H), 7.48-7.00 (m, 16H, Ar-H), 5.09 (qt, JP-H = 12.0 Hz,
3JH-H = 6.8 Hz, CH3, 1H, CH), 4.92 (s, 5H, Cp-H), 1.22 (dt,
3
3JP-H = 13.5 Hz, JH-H = 7.6 Hz, CH3). 31P{1H} NMR
(CDCl3, 162 MHz, 293 K): δ 27.45 (s, 2P). MS(EI): m/z
(%)=692 (M, 100), 565 (M - I, 36), 378 (49). Anal. Calcd for
C31H29IP2Ru (691.5): C, 53.85; H, 4.23. Found: C, 53.69; H, 4.23.
trans-(η5-Cyclopentadienyl)[1,1-bis(diphenylphosphanyl)ethane-
KP)]iodoruthenium(II), trans-[CpRu(Dppm-Me)Cl]. A solution
of trans-[CpRu(Dppm-Me)Cl] (89 mg, 0.15 mmol) and [Bu4N]I
(482 mg, 1.3 mmol) in 10 mL of CH2Cl2/ether (9:1) was stirred at
room temperature. After evaporation of the solvent the residue
was subjected to chromatography on a short silica gel column
using CH2Cl2/ether (9:1) to give trans-[CpRu(Dppm-Me)I] (63
mg, 61%). Orange needles suitable for X-ray analysis were
obtained by recrystallization from ether/hexane.
trans-[CpRu(Dppm-Me)Cl]: 1H NMR (CDCl3, 400 MHz,
293 K): δ 7.90-7.83 (m, 4H, Ar-H), 7.52-7.45 (m, 4H, Ar-H),
7.38-7.32 (m, 12H, Ar-H), 7.48-7.00 (m, 16H, Ar-H),
5.59-5.47 (m, 1H, CH), 4.41 (s, 5H, Cp-H), 1.08 (dt, 3JP-H
=
3
15.4 Hz, JH-H =7.8 Hz, CH3). 31P{1H} NMR (CDCl3, 162
MHz, 293 K): δ 21.03 (s, 2P). MS(EI): m/z (%) = 600 (M, 96),
352 (100).
1
cis-[CpRu(Dppm-Me)Cl]: H NMR (CDCl3, 400 MHz, 293
1H NMR (CDCl3, 400 MHz, 293 K): δ 7.88-7.82 (m, 4H, Ar-
K): δ 7.72-7.65 (m, 4H, Ar-H), 7.48-7.00 (m, 16H, Ar-H), 4.83
(s, 5H, Cp-H), 4.92-4.69 (m, 1H, CH), 1.24 (dt, 3JP-H = 13.2
Hz, 3JH-H = 7.6 Hz, CH3). 31P{1H} NMR (CDCl3, 162 MHz,
293 K): δ 31.82 (s, 2P). MS(EI): m/z (%) = 600 (M, 100), 352
(97). Anal. Calcd for C31H29ClP2Ru (600.0): C, 62.05; H, 4.87.
Found: C, 62.35; H, 5.00.
3
H), 7.41-7.23 (m, 16H, Ar-H), 5.63 (dt, JP-H = 10.1 Hz,
3JH-H = 8.1 Hz, CH3), 4.58 (s, 5H, Cp-H), 1.48 (dd, 3JP-H = 16
Hz, 3JH-H = 8.1 Hz, CH3). 31P{1H} NMR (CDCl3, 162 MHz,
293 K): δ 20.08 (s, 2P). MS(EI): m/z (%) = 692 (M, 88), 565 (M
- I, 40), 378 (100).
cis-(η5-Cyclopentadienyl)[1,1-bis(diphenylphosphanyl)ethane-
KP)]iodoruthenium(II), cis-[CpRu(Dppm-Me)I]. A solution of
cis-[CpRu(Dppm-Me)Cl] (105 mg, 0.175 mmol) and KI (10 g,
0.060 mol) in methanol (30 mL) was refluxed for 1 h. After
cooling, the solvent was removed. The residue was dissolved in
CH2Cl2, and the solution was filtered on Celite and evaporated.
The residue was recrystallized from methanol to give cis-[CpRu-
Supporting Information Available: 1H NMR and 31P{1H}
NMR spectra of the complexes, CIF files giving the crystal-
lographic data for the complexes in Table 1. This material is
available free of charge via the Internet at http://pubs.acs.org.
X-ray data has been deposited at the CCDC, Cambridge U.K.
(659547-659551).