Water-soluble phosphines: Part XII. Pd catalyzed P-C coupling reactions: A novel synthetic route to cationic phosphines with para- and meta-guanidiniumphenyl moieties

Article abstract of DOI:10.1016/S0022-328X(00)00151-0

Mono- and bifunctional guanidinium phosphines (3c, 4a, 4b, 5a-5d, 5f) containing para-and meta-guanidiniumphenyl moieties -C₆H₄-NH-C(NH₂)(NR₂)⁺ (R=H, Me) are accessible in high yields by Pd catalyzed P-C coupling reactions between iodophenyl guanidines I-C₆H₄-NH-C(NH)NR₂ (meta-, para-isomers; R=H, Me) and phenyl- or diphenylphosphine. The X-ray structure of 3c·MeOH (space group P2₁2₁2₁) has been determined, showing a planar guanidinium group in a NH-O and NH-Cl hydrogen bridged arrangement. Pd(II) and Mo(0) complexes of 5c have been synthesized. The influence of the cationic guanidinium group on the electronic and steric parameters of 5c is discussed. A comparative study of 5c, phosphonated and sulfonated phosphine ligands in the biphasic Pd catalyzed Suzuki-type coupling between m-bromophenyldiphenyl phosphine oxide and para-tolylboronic acid shows 5c to be less active than Ph₂P-C₆H₄-4-PO₃Na₂.

Full text of DOI:10.1016/S0022-328X(00)00151-0

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 602 (2000) 158–169
Water-soluble phosphinesꢀ
Part XII. Pd catalyzed PꢀC coupling reactions: a novel synthetic
route to cationic phosphines with para- and
meta-guanidiniumphenyl moieties
Peter Machnitzki a, Michael Tepper a, Kirsten Wenz a, Othmar Stelzer a,*,
Eberhardt Herdtweck b
a Fachbereich 9, Anorganische Chemie, Bergische Uni6ersita¨t-GH Wuppertal, Gaußstraße 20, D-42097 Wuppertal, Germany
b Anorganisch Chemisches Institut, Technische Uni6ersita¨t Mu¨nchen, Lichtenbergstraße 4, D-85748 Garching, Germany
Received 5 November 1999; accepted 17 February 2000
Abstract
Mono- and bifunctional guanidinium phosphines (3c, 4a, 4b, 5a–5d, 5f) containing para-and meta-guanidiniumphenyl moieties
ꢀC6H4ꢀNHꢀC(NH2)(NR2)+ (R=H, Me) are accessible in high yields by Pd catalyzed PꢀC coupling reactions between iodophenyl
guanidines IꢀC6H4ꢀNHꢀC(NH)NR2 (meta-, para-isomers; R=H, Me) and phenyl- or diphenylphosphine. The X-ray structure of
3c·MeOH (space group P212121) has been determined, showing a planar guanidinium group in a NHꢀO and NHꢀCl hydrogen
bridged arrangement. Pd(II) and Mo(0) complexes of 5c have been synthesized. The influence of the cationic guanidinium group
on the electronic and steric parameters of 5c is discussed. A comparative study of 5c, phosphonated and sulfonated phosphine
ligands in the biphasic Pd catalyzed Suzuki-type coupling between m-bromophenyldiphenyl phosphine oxide and para-tolyl-
boronic acid shows 5c to be less active than Ph2PꢀC6H4ꢀ4-PO3Na2. © 2000 Published by Elsevier Science S.A. All rights reserved.
Keywords: meta-, para-Guanidiniumphenyl phosphines; Pd catalyzed PꢀC coupling; X-ray structure; Ligand properties; Suzuki coupling
1. Introduction
tion as ligands in catalytically active transition metal
complexes, although some of them (e.g. AMPHOS, B)
have been known for more then two decades [5].
Recently there has been an increasing interest in
aqueous biphasic catalysis for the syntheses of organic
compounds on industrial and laboratory scales [2]. This
is mainly due to the environmental benefits of using
water as a solvent and the ease by which the catalysts
can be recycled. The complexes applied as catalysts
gain their water-solubility by incorporation of strongly
hydrophilic phosphine ligands. The most widely studied
complex catalysts are those of tris-meta-sulfona-
tophenylphosphine (TPPTS, A) [3], the prototype of
anionic phosphine ligands. In contrast, cationic phos-
phines have, until recently [4], received only little atten-
ꢀ For Part XI see Ref. [1].
* Corresponding author. Tel.: +49-202-4392517; fax: +49-202-
4393053.
0022-328X/00/$ - see front matter © 2000 Published by Elsevier Science S.A. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 0 ) 0 0 1 5 1 - 0

P. Machnitzki et al. / Journal of Organometallic Chemistry 602 (2000) 158–169
159
Cationic phosphines
C
(GUAPHOS) containing
cyanamides R2NꢀCN (R=H, Me) with the correspond-
ing iodoanilinium chlorides and subsequent deprotona-
tion of the resulting guanidinium salts 1a and 1c with
KOH (Eqs. (2a) and (2b)).
meta-guanidiniumphenyl moieties have been obtained
by us very recently in moderate overall yields using a
multistage synthesis [6a]. Due to the highly polar func-
tions these ligands show a pronounced solubility in
water. The anion binding capacity of the guanidinium
groups [7a,8] should exert some precoordination and
preorientation of anionic substrates in the periphery of
catalyst complexes containing these ligands. They were
shown to be very active in Pd mediated CꢀC coupling
reactions between aryl iodides and alkynes [6a,b]
(Castro–Stephens–Sonogashira reaction [6c]) and Rh
catalyzed hydroformylation of olefins in two-phase sys-
tems [9]. Due to their potential as catalyst ligands a
single stage high yield synthesis for the meta- and
para-isomers of these cationic phosphines was therefore
highly desirable.
In contrast to the cationic phosphines of the AM-
PHOS type, guanidinium phosphines are stable even in
strongly basic media and may therefore be employed as
catalyst components in Heck type and Suzuki type
coupling reactions [10]. Deprotonation of the guani-
dinium group in type C ligands affords the neutral
guanidino phosphines D which are soluble in the organic
substrate phase of aqueous two-phase systems where
they effect the catalytic conversion. Recovery of the
catalyst and its separation from the products is simply
achieved by acidification of the aqueous phase, the
cationic water-soluble ligands C and their complexes
being formed back again.
Reaction of 2a and 2c with Ph2PH in presence of a
catalytic amount of palladium(II) acetate affords 3a and
3b in high yields (Eq. (3a)). Due to strongly basic
character of the guanidino groups in 2a and 2c no extra
base has to be added as in case of the PꢀC coupling
reactions depicted in Eq. (1). For phenylguanidine a pKa
value of 10.77 has been reported in the literature [7]. In
order to get analytically pure samples of the para-guani-
diniumphenylphosphines the hexafluorophosphate of
the cation in 3b was precipitated from the reaction
mixture. Deprotonation of the guanidinium group with
NaOH and subsequent addition of HCl yields the chlo-
ride 3c (Eq. (3b)). Deprotonation of 3a with NaOH
yields the guanidinophosphine 3d (Eq. (3c)). On reaction
of 3d with ammonium hypophosphite or diphenylphos-
phinic acid in methanol, ethanol or glyme the phosphi-
nates 4a and 4b are formed as colorless precipitates in
high yields (Eq. (3d)).
Palladium catalyzed PꢀC coupling of primary and
secondary phosphines with mono and multiply function-
alized bromo- or iodobenzenes as developed by us has
shown to provide a straightforward synthetic approach
to an extended range of tailor-made hydrophilic phos-
phine ligands (Eq. (1)) [11]. Using this synthetic strategy
para- and meta-isomers of type C ligands should be
accessible by a single stage PꢀC coupling reaction be-
tween Ph2PH or PhPH2 and iodo- or bromophenyl-
guanidines E which function as eletrophiles and bases
due to the strongly basic guanidino group. Preliminary
work has been published by us elsewhere [12].
2. Syntheses of monocationic
para-guanidiniumphenylphosphines
The para-iodophenylguanidines 2a and 2c may be
obtained in a straightforward manner by reaction of the

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P. Machnitzki et al. / Journal of Organometallic Chemistry 602 (2000) 158–169
In the 31P{1H}-NMR spectra 3a–3d, 4a and 4b
The molecular structure of the cationic part of
3c·CH3OH is shown in Fig. 1. Selected bond dis-
tances, angles and contact distances are listed in
Table 1, while crystallographic details are given in
Table 3. The N atoms N(1), N(2), N(3) and the car-
bon atom C(1) of the guanidinium group in 3c lie
almost in the same plane, the sum of the NꢀCꢀN
bond angles being close to 360°. The carbon nitrogen
bond lengths (C(1)ꢀN(1) 1.337(6), C(1)ꢀN(2) 1.329(7),
show singlets in the range between l= −1 and −6
for the Ph2P group. The lP values for the hypophos-
phite and diphenylphosphinate anions in 4a and 4b
are shifted to high field compared with the corre-
sponding values of the hydrophosphorous acid and
diphenylphosphinic acid [13] indicating the proton
transfer to the basic guanidino group on their forma-
tion according to Eq. (3d). The bidentate anions
R2PO−2 (R=H, Ph) in 4a and 4b are capable
of forming hydrogen bridged ion pairs F with the
guanidinium moieties in the solid state or possibly
even in low dielectric environment. The prototype
of this interaction is represented by the structure
of guanidinium bicarbonate, which has been consid-
ered as a model for the bicarbonate anion binding
site of the transferrines [14a]. According to an X-
ray structural analysis the two oxygen atoms of the
planar bicarbonate form hydrogen bonds with differ-
ent nitrogen atoms of the guanidinium cation (G)
[14b].
,
C(1)ꢀN(3) 1.326(7) A) are halfway between the nor-
,
mal CꢀN single bond length (1.47 A) and the pure
,
double bond lengths (1.24 A) [19] in a range typical
for carbon substituted guanidinium ions [20] and
the parent guanidinium ion [21]. The NMe2 sub-
stituent with a planar geometry at N(3) is rotated
counter clockwise around the C(1)ꢀN(3) axis (di-
hedral angle C(2)ꢀN(3)ꢀC(1)ꢀN(1)= −16.8(7)°) thus
lowering the steric repulsion between N(1)H and
N(2)H2 and the two methyl groups. The plane defined
by the guanidinium system and that of the p-
phenylene spacer are rotated against each other as
indicated by the dihedral angle C(1)ꢀN(1)ꢀC-
(14)ꢀC(13)= −51.9(7)°. While the PꢀC bond lengths
between P and C(21) and C(31) are in the typical
The 13C{1H}-NMR spectra of 3a–3d, 4a and 4b
show eight signals for the aromatic carbon atoms
which could be assigned using DEPT experiments [15]
and by comparison with pertinent data of
triphenylphosphine [16a] and related phenylguanidines
[16b]. For 3c, 4a and 4b 13C-NMR resonances (lC=
155.5–157.8) are observed in the range typical for
guanidinium carbon atoms [17]. The 15N{1H}-NMR
spectrum of 3c shows three well-separated resonances
at l15N= −299.3, −281.4 and −303.8 which may
be assigned to the NH, NH2 and NMe2 groups, re-
spectively [18]. For 4a two 15N-NMR signals at
,
range [22], the distance PꢀC(11) (1.817(4) A) is some-
what shortened.
4. Syntheses of dicationic
meta-guanidiniumphenylphosphines
1
l15N= −282.2 (NH, J(NH)=92.5 Hz) and −305.7
1
(NH2, J(NH)=91.8 Hz) are observed showing dou-
For the syntheses of the dicationic meta-guanidini-
umphenylphosphines the meta-iodophenyl guanidines
2b and 2d have been employed as starting materials.
The guanidinium salts 1b and 1d may be obtained in
an analogous manner as 1a and 1c by reaction of the
cyanamides R2NꢀCN (R=H, Me) with the corre-
sponding iodoanilinium salts (Eq. (2a)). They were
deprotonated with KOH to give 2b or 2d, respec-
tively, in high yields (Eqs. (2a) and (2b)).
On reaction of the meta-iodophenylguanidine 2d
with PhPH2 using Pd(PPh3)4 [23] as catalyst, the io-
dide of the guanidiniumphosphine 5a [6a] was ob-
tained in almost quantitative yield (Eq. (4a)). If the
meta-bromophenylguanidine 2e was employed instead
of its iodo analog 2d, the PꢀC coupling reaction (Eq.
(4b)) proceeds much slower, the phosphinophenyl
guanidinium bromide 5b being formed in small yields
only. 5b and 5c are accessible by deprotonation of 5a
(Eq. (4c)) in a two-phase system (CH2Cl2/H2O) and
subsequent reprotonation of the intermediate
guanidino phenylphosphine 5d with HBr or HCl, re-
spectively (Eq. (4d)).
blet or triplet fine structure, respectively.
3. X-ray structure of 3c·CH3OH
So far there are no reports in the literature on the
structure of phosphines containing peripheral guani-
dinium moieties. In order to gain detailed information
about the geometry of the NHꢀC(NH2)(NMe2) group
and its orientation with respect to the plane of the
p-phenylene spacer unit in 3c a structure determina-
tion has been performed. On recrystallization of 3c
from methanol crystals of composition 3c·CH3OH
were obtained. In the unit cell the cations of 3c are
interconnected by hydrogen bridges between NH(1)
and NH(2) and the chloride ions (N(1)···Cl 3.220(4)
,
,
A, N(2)···Cl 3.222(5) A) forming chains parallel to
the a-axis. They are coupled by methanol molecules
,
via OH···Cl and NH···O bridges (N(2)···O 2.804(7) A,
,
O···Cl 3.047(5) A) to give double strands.

P. Machnitzki et al. / Journal of Organometallic Chemistry 602 (2000) 158–169
161
Iodophenyl guanidinium salts may be employed as
starting materials instead of the corresponding
iodophenyl guanidines for the syntheses of the dica-
tionic phosphino guanidiniumphenyl halides. In this
case extra base had to be added, however, in order to
bind the HI formed during the reaction. Thus PꢀC
coupling of the iodophenyl guanidinium chloride 1b
with PhPH2 was achieved using a 1:2 mixture of dipal-
ladium trisbenzylideneacetone and 1,3-bisdiphenylphos-
phinopropane as the catalyst. Tri-n-butylamine was
added as the base. In order to yield a product 5f with a
uniform anion the primary reaction product 5e was
deprotonated with KOH to give the guanidinophos-
phine which on reprotonation with HCl affords the
phosphinoguanidiniumphenyl chloride 5f (Eqs. (5a) and
(5b)).
The meta-guanidiniumphenyl phosphines 5a–5c, 5f
and the meta-phenylguanidino phosphine 5d show sin-
glets at lP of about −5.0 in the 31P{1H}-NMR spec-
tra. Assignments of the resonances in the
13C{1H}-NMR spectra could be achieved at least in
Fig. 1. (a) ORTEP style plot of the cationic part of (3c·CH3OH) with the atomic labeling scheme. Thermal ellipsoids are drawn at the 50%
probability level. Hydrogen atoms are omitted for clarity. (b) Stereo PLUTON plot of (3c·CH3OH) showing the hydrogen bridged network.

162
P. Machnitzki et al. / Journal of Organometallic Chemistry 602 (2000) 158–169
Table 1
tion in the guanidinium form of
L-arginine [18] the
,
Selected interatomic distances (A) and angles (°) for 3c·CH3OH
rotation about the CꢀN(H,Ph) bond is fast on the
NMR time scale, so that averaged peaks for the NH2
groups are observed in both cases.
Bond lengths
PꢀC(11)
PꢀC(21)
PꢀC(31)
1.817(4)
1.848(5)
1.836(5)
1.358(10)
1.337(6)
1.432(7)
1.329(7)
1.465(8)
1.456(7)
1.326(7)
1.408(7)
1.391(7)
1.396(7)
1.366(7)
C(14)ꢀC(15)
C(15)ꢀC(16)
C(21)ꢀC(26)
C(21)ꢀC(22)
C(22)ꢀC(23)
C(23)ꢀC(24)
C(24)ꢀC(25)
C(25)ꢀC(26)
C(31)ꢀC(36)
C(31)ꢀC(32)
C(32)ꢀC(33)
C(33)ꢀC(34)
C(34)ꢀC(35)
C(35)ꢀC(36)
1.389(7)
1.374(7)
1.386(8)
1.395(8)
1.376(8)
1.394(8)
1.397(8)
1.373(8)
1.407(7)
1.380(8)
1.392(9)
1.354(10)
1.364(10)
1.390(8)
5. Ligand properties and coordination chemistry of 5c
OꢀC
N(1)ꢀC(1)
N(1)ꢀC(14)
N(2)ꢀC(1)
N(3)ꢀC(2)
N(3)ꢀC(3)
N(3)ꢀC(1)
C(11)ꢀC(12)
C(11)ꢀC(16)
C(12)ꢀC(13)
C(13)ꢀC(14)
In order to get information about the influence of the
positive charge of the guanidinium groups on the ligand
properties of guanidinium phosphines a comparative
study of the Pd(II) complexes and tetracarbonyl molyb-
denum(0) complexes of dicationic 5c and dianionic
phosphines (disulfonated dibenzophosphole [24a],
monophosphonated Ph2PꢀC6H4ꢀ4-PO3Na2 [24b] and
para-TPPDS [24c]) with a common skeleton was under-
taken. The tetracarbonyl molybdenum(0) complexes of
Ph3P [25a] and TPPTS [25b] were included into these
studies for sake of comparison.
Bond angles
C(11)ꢀPꢀC(21)
C(11)ꢀPꢀC(31)
C(21)ꢀPꢀC(31)
C(1)ꢀN(1)ꢀC(14)
C(1)ꢀN(3)ꢀC(3)
C(2)ꢀN(3)ꢀC(3)
C(1)ꢀN(3)ꢀC(2)
N(2)ꢀC(1)ꢀN(3)
N(1)ꢀC(1)ꢀN(2)
102.0(2)
102.7(2)
103.1(2)
124.3(4)
121.1(5)
117.7(5)
121.2(4)
120.0(5)
120.3(5)
N(1)ꢀC(1)ꢀN(3)
PꢀC(11)ꢀC(12)
PꢀC(11)ꢀC(16)
N(1)ꢀC(14)ꢀC(15)
N(1)ꢀC(14)ꢀC(13)
PꢀC(21)ꢀC(26)
PꢀC(21)ꢀC(22)
PꢀC(31)ꢀC(32)
PꢀC(31)ꢀC(36)
119.6(4)
117.0(3)
126.0(4)
118.6(5)
120.9(4)
116.7(4)
124.5(4)
116.5(4)
125.0(4)
D H A
DꢀH
H···A
D···A
DꢀH···A
i N(1)ꢀH(1)···Cl
a
0.78(5)
0.78(5)
0.83(6)
0.84(4)
0.97(7)
2.45(5)
2.05(5)
2.40(6)
2.23(4)
2.69(7)
3.220(4)
2.804(7)
3.222(5)
3.047(5)
3.520(6)
173(4)
161(5)
169(5)
168(4)
144(5)
–
N(2)ꢀH(2)···O
i N(2)ꢀH(3)···Cl
b
–
OꢀH(7)···Cl
C(23)ꢀH(231)···Cl
i Symmetry code for equivalent atoms: a (x−0.5, −y+0.5, −z+
–
1); b (x+0.5, −y+0.5, −z+1).
–
On reaction of the highly water-soluble dicationic
phosphine 5c (L) with bisbenzonitrile palladium(II)
chloride in an aqueous suspension a Pd(II) complex 6
of composition Cl2PdL2 is formed (Eq. (6)). While in
methanol (dielectric constant 32.3 [26a], dipole moment
69 D [26b]) the trans-isomer of 6 predominates (the
trans:cis ratio being about 95:5) in aqueous solution
(dielectric constant 80.4 [26a], dipole moment 1.83 D
[26b]) the cis-isomer is found exclusively.
This is consistent with the observation that the
amount of the cis isomers of Cl2PdL2 complexes gener-
ally increases as the dielectric constant or the dipole
moment of the solvent increases [27]. The assignment of
the cis- or trans-structure of 6 is based on the analysis
of the 13C{1H}-NMR spectra, which for the ipso-,
ortho- and meta-carbon atoms show triplet fine struc-
ture in case of the trans-isomer, while five or six line
patterns are observed for the cis-isomer [28]. The qua-
ternary guanidinium carbon atoms give rise to singlets
in both isomers. The general observation that for a
particular phosphine ligand the lP value of the cis-iso-
mer is downfield from that of the trans isomer [29]
provides further support of the assignments given.
part by comparison with relevant data of Ph3P and
with the aid of DEPT 13C-NMR spectra. 13C-NMR
signals at l=157.8, 152.7 and 155.2 may be assigned to
the guanidinium carbon atoms of 5c, 5d or 5f, respec-
tively. In case of the neutral guanidino phosphine 5d
the 13C-NMR signal of the ipso-carbon atom attached
to nitrogen is shifted downfield to l=150.8 (3J(PC)=
7.1 Hz). The same applies for the chemical shift of the
ipso-carbon atom in 3d (l=151.3) as compared with
that of 4a (l=137.0) or 4b (l=137.0), respectively. A
similar lowfield shift is observed for the 13C-NMR
resonance of the ipso-carbon on going from the anilin-
ium cation (l=128.6) to aniline (l=147.0) [16a]. The
15N{1H}-NMR spectrum of 5f reveals two resonances
at l= −283.7 and −306.4 which correspond to the
NH and the NH2 groups. The resonance at l= −283.7
shows a doublet fine structure (4J(15N31P)=2.1 Hz). In
the 15N-NMR spectrum the signal at l= −283.7 ap-
pears as a doublet (1J(15N1H)=91.8 Hz) while the
resonance at l= −306.4 is split into
a triplet
(1J(15N1H)=92.0 Hz). This is in line with the results
obtained for 4a (see above). In analogy with the situa-

P. Machnitzki et al. / Journal of Organometallic Chemistry 602 (2000) 158–169
163
The disulfonated dibenzophosphole [24a] (L1) reacts
with bisbenzonitrile palladium(II) chloride in an
analogous way as 5c, a complex of composition
Cl2PdL2 being formed. In aqueous solution only the
cis-isomer of 7 is present as indicated by the ‘filled in
doublet’ fine structure of the signals in the 13C{1H}-
NMR spectrum. For the Pd(II) complex of TPPTS (8)
[30c] two 31P-NMR resonances (l=34.3 and 25.3) are
observed, which may be assigned to the cis and trans-
isomer. Using the correlation between the lP chemical
shift of complexes trans-Cl2PdL2 and the sterical
parameter qTol [31] of the ligands L a value of ca. 148°
can be estimated for 5c [30a,b]. This value compares
well with that of the parent phosphine Ph3P (lP(trans-
L2PdCl2)=13.3 [30a], q=145° [31]) characterizing 5c
as somewhat less bulky than TPPTS (qTol=166°) [30b].
The cationic molybdenum complex 9a has been ob-
tained by reaction of norbornadiene tetracarbonyl
molybdenum(0) with the aqueous solutions of 5c. The
anionic Mo(0) complexes of disulfonated dibenzophos-
phole, phosphonated and disulfonated phosphine are
accessible in an analogous way [24a] (Eq. (7)).
The SMo values obtained according to Eq. (8) for 5c
i
and the anionic phosphine ligands with para-sulfonated
and phosphonated aromatic substituents are collected
in Table 2. For comparison purposes the corresponding
values of Ph3P [25a] and TPPTS [25b] have been in-
cluded. The S values of the ligands 5c, L1ꢀL3, Ph3P
Mo
i
and TPPTS do not differ significantly. The coordina-
tion shifts of the 31P resonances and the coupling con-
stants 2J(PP) are also quite similar. These results
indicate, that the donor properties are not greatly
changed by introduction of the charged functionalities
[NHꢀC(NH2)(NMe2)]+ or PO32−, SO−3 into the skele-
ton of Ph3P. Similar results have been obtained for
AMPHOS [5], its electron donor properties in
Fe(CO)4L, W(CO)5L and Mo(CO)5L complexes being
only slightly lower than those of Ph3P and Ph2MeP.
6. Suzuki aryl coupling mediated by Pd complexes of
cationic and anionic phosphines
Palladium mediated cross coupling of aryl halides
and aryl boronic acids (Suzuki coupling [10]) is a ver-
satile method for the synthesis of functionalized unsym-
metrical biaryls. These compounds are of po-
tential use in pharmaceutical chemistry and for the
preparation of liquid crystalline materials [34]. To ex-
amine the effect of the catalyst ligand, we studied the
cross coupling reaction of meta-bromophenyl
diphenylphosphine oxide 10 [35] with para-tolylboronic
acid to yield the 4-methyl-1,1%-biphenyl substituted
phosphine oxide 11 (Eq. (9)). The reaction was per-
formed in a two-phase system using a 1:1 mixture of
ethyleneglycol–water as the polar phase and toluene as
the organic phase. Potassium carbonate was employed
as the base.
The w(CO)A1(1) stretching frequency of the com-
plexes cis-(CO)4Mo(R1R2R3P)2 has been proposed as
measure for the electronic donor–acceptor character of
the phosphorus ligands L. The definition of the individ-
ual electronic parameters of the substituents Ri at phos-
phorus is given in Eq. (8) using the bulky tBu3P as
Mo
i
standard [32]. The  parameters thus obtained corre-
late very well [33] (correlation coefficient R=0.9943)
Ni
i
with the corresponding values  derived by Tolman
form the w(CO)A1 stretching frequency of R1R2R3Pꢀ
Ni(CO)3 complexes [31].
Table 2
Mo
i
w(CO) carbonyl stretching frequencies (cm−1), S
parameters and coordination chemical shift values DlP for the complexes cis-Mo(CO)4L2
(L=5c, L1ꢀL3 [24a], Ph3P, TPPTS) (see Eq. (7) for the definition of L1ꢀL3)
2J(PP) e
Mo
i
d
L
A(12)
A(11)
B1
B2
S
DlP
5c
2020 a
2016 a
2018 a
2021 a
2023 b
2025 a
2023 c
1922
1918
1917
1921
1929
1931
1911
1907
1901
1903
1908
1911
1914
1909
1884
1886
1882
1887
1899 [25a]
1898 [25b]
1859 [25b]
15
13
11
16
18
20
18
44.5 f
26
23
19
L1
43.8 h
47.2 g
45.4 i
L2
L3
Ph3P
TPPTS
a 2-Methoxyethanol.
b n-Hexane.
c CH3CN, [Na-kryptofix-221]6[cis-(CO)4Mo{P(C6H4ꢀm-SO3)3}2].
d DlP=lPcomplex−lPligand
.
e In Hz, determined from the CO-13C{1H}-NMR spectra (X parts of ABX spectra).
f D2O.
g H2O/d6-DMSO.
h CD3OD.
i D2O/isopropanol.

164
P. Machnitzki et al. / Journal of Organometallic Chemistry 602 (2000) 158–169
C7H8Mo(CO)4 [39], and Ph2P(O)ꢀC6H4ꢀ4-Br [35] were
prepared according to literature methods. Cyanamide,
dimethylcyanamide, ammonium hypophosphite, p-
tolylboronic
acid,
and
1,3-bisdiphenylphos-
phinopropane were purchased from Aldrich GmbH or
Strem Chemicals. Starting materials were characterized
1
by H-, 13C{1H}- and 31P{1H}-NMR spectroscopy and
1
mass spectrometry. H-, 13C{1H}-, and 31P{1H}-NMR
spectra were recorded on a Bruker AC 400 or AM 250
and a Jeol FX90 Q Fourier transform spectrometer.
Mass spectra were obtained on a Varian MAT 311A
spectrometer.
Fig. 2. Conversion vs. time diagram for the two-phase Suzuki-cou-
pling of 10 with p-toluene boronic acid (ꢁ: 5c, : Ph2PꢀC6H4ꢀ4-
PO3Na2).
7.1. Synthesis of the 4-iodophenyl guanidines 2a and 2c
A total of 40.0 g (156.6 mmol) or 70.0 g (274.0
mmol) of finely grounded 4-iodophenylammonium
chloride and 6.3 g (150.0 mmol) of cyanamide or 21.1 g
(301.0 mmol) of dimethylcyanamide was mixed to-
gether and the mixture was heated to 160°C for 10 min.
The solution obtained after addition of 500 ml of water
was extracted with three aliquots of 100 ml of ether.
The aqueous phase was separated and evacuated at 1
mbar in order to remove the ether dissolved in the
solution. Thereafter conc. aqueous NaOH solution was
added until a pH value of 12 was reached. The precipi-
tate formed was collected by filtration on a Buchner
funnel and washed with water until the filtrate showed
no alkaline reaction. The precipitate was dried in vacuo
(20°C, 0.1 mbar). Yields: 28.1 g (72%) 2a, 54.6 g (69%)
2c.
The catalysts were formed in situ by an exchange
reaction between Pd( Ph3P)4 [23] and the water-soluble
ligands (employed in a 1:20 molar ratio) in a two-phase
system (dichloromethane–water). In order to elaborate
the influence of the ligand charge on the catalytical
activity of their Pd(0) complexes the phosphines L1
[24a] and L2 [24b] were studied in addition to the
cationic phosphine 5c. Using the Ph2P(O) groups in 10
(lP=29.2) and 11 (lP=30.6) as a probe the conver-
sion rate could be determined quite conveniently by
31P{1H}-NMR spectroscopy. The results for 5c and
Ph2PꢀC6H4ꢀ4-PO3Na2 are collected in Fig. 2.
2a. Anal. Found: C, 32.50; H, 3.10; N, 16.0. C7H8IN3
(261.1). Calc.: C, 32.21; H, 3.09; N, 16.09%. M.p.=
1
155°C; H-NMR (CD3CN, l): 4.60 (NH2), 6.60–6.63,
7.50–7.60 (arom. H); 13C{1H}-NMR (d6-acetone, l):
154.3; 152.4; 139.1, 127.3, 84.1; 15N{1H}-NMR (d6-
DMSO, l): −307.3 (NH2).
The anionic ligand Ph2PꢀC6H4ꢀ4-PO3Na2 [24b] is
significantly more efficient in this CꢀC coupling reac-
tion compared with the cationic 5c, both forming a
homogeneous catalyst system. The anionic diben-
zophosphole L1 was inactive as catalyst ligand. In the
case of 5c deprotonation of the guanidinium group by
K2CO3 occured, the neutral ligand 5d and its Pd com-
plex were dissolved in the organic phase as indicated by
the yellow color and the signal at lP= −5.7 in the
31P{1H}-NMR. Before work-up the reaction mixture
the guanidinium phosphine was extracted into the
aqueous solution with dilute hydrochloric acid.
2c. Anal. Found: C, 37.70; H, 4.20; N, 14.60.
C9H12IN3 (289.1). Calc.: C, 37.39; H, 4.18; N, 14.53%.
1
M.p.=101°C; H-NMR (CD3CN, l): 2.88 (CH3), 4.30
(NH2), 6.5–6.6, 7.4–7.5 (arom. H); 13C{1H}-NMR
(CD3CN, l): 153.9, 152.7, 138.9, 126.6, 88.3, 37.8
(CH3).
7.2. Synthesis of the 3-iodophenyl guanidines 2b and 2d
The mixtures of 58.2 g (228.0 mmol) or 52.6 g (205.9
mmol) of 3-iodophenylammonium chloride and 9.15 g
(232.0 mmol) of cyanamide or 14.4 g (205.9 mmol) of
dimethylcyanamide were heated to 130°C for 10 min.
After the reaction was completed 150 ml of water was
added to the reaction mixtures. The solutions obtained
were extracted with three aliquots of 100 ml of diethyl
ether. To the aqueous phase conc. KOH was added
until a pH value of 12 was reached and the solution was
extracted with three aliquots of dichloromethane. The
7. Experimental
For experimental details, see Part XI of this series [1].
Diphenylphosphine [36a], phenylphosphine [36b],
Ph2P(O)(OH) [37], Pd(Ph3P)4 [23], PdCl2(PhCN)2 [38],

P. Machnitzki et al. / Journal of Organometallic Chemistry 602 (2000) 158–169
165
collected organic phases were dried over magnesium
sulfate. After evaporation of all volatiles in vacuo 2b
and 2d were obtained as pale yellow crystals. Yields:
47.6 g (80%) 2b, 48.2 g (81%) 2d.
2b. Anal. Found: C, 32.50; H, 3.20; N, 16.1. C7H8IN3
(261.1). Calc.: C, 32.21; H, 3.09; N, 16.09%. M.p.=
125°C; 1H-NMR (CD3CN, l): 4.98 (NH2), 6.8–7.3
(arom. H); 13C{1H}-NMR (CD3CN, l): 154.8, 153.9,
133.6, 132.1, 131.0, 124.3, 95.8.
2d. Anal. Found: C, 37.21; H, 4.13; N, 14.25.
C9H12IN3 (289.1). Calc.: C, 37.39; H, 4.18; N, 14.53%.
1H-NMR (CDCl3, l): 2.99 (CH3), 6.85–7.30 (arom. H);
13C{1H}-NMR (CDCl3, l): 152.7, 152.6, 132.6, 130.9,
130.5, 123.0, 95.0, 37.7 (CH3).
4a. Anal. Found: C, 59.18; H, 5.55; N, 10.78.
C19H21N3O2P2 (385.3). Calc.: C, 59.22; H, 5.49; N,
1
10.90%. H-NMR (CD3OD, l): 7.14 (1J(PH)=502.8,
H2PO−2 ), 7.2–7.6 (arom. H). 13C{1H}-NMR (CD3OD,
l): 157.8, 138.1 (J=10.9 Hz), 137.8 (J=12.7 Hz),
137.0, 136.2 (J=20.3 Hz), 134.8 (J=19.9 Hz), 130.1,
129.7 (J=6.9 Hz), 125.8 (J=7.1 Hz); 31P{1H}-NMR
(CD3OD, l): −1.0 (s3-P), 8.3 (1J(PH)=503.1 Hz, t,
H2PO2); 15N{1H}-NMR (CH3OH, CD3OD, l): −282.2
(J=92.5 Hz, NH), −305.7 (J=91.8, NH2).
4b. Anal. Found: C, 69.22; H, 5.40; N, 7.80.
C31H29N3O2P2 (537.5). Calc.: C, 69.27; H, 5.44; N,
7.82%. 13C{1H}-NMR (CD3OD, l): 157.6, 140.2 (J=
131.4 Hz), 138.1 (J=10.9 Hz), 137.4 (J=12.6 Hz),
137.0, 136.1 (J=20.4 Hz), 134.7 (J=19.8 Hz), 132.0
(J=9.5 Hz), 131.1 (J=2.6 Hz), 130.3, 129.7 (J=7.0
Hz), 128.9 (J=12.1 Hz), 125.7 (J=7.1 Hz); 31P{1H}-
NMR (CD3OD, l): −1.2 (s3-P), 26.6 (Ph2PO2−).
7.3. Synthesis of 4-diphenylphosphinophenyl guanidine
(3d) and the 4-diphenylphosphinophenyl guanidinium
salts 4a and 4b
7.3.1. Synthesis of 3d
7.4. Synthesis of N,N-dimethyl-N%-(4-diphenylphos-
phino)phenyl guanidinium chloride (3c)
A total of 6.92 g (37.2 mmol) of diphenylphosphine
and 9.70 g (37.2 mmol) of 2a was dissolved in 100 ml of
dimethylacetamide. Oxygen dissolved in this solution
was thoroughly removed by repeated freeze–thaw cy-
cles. After addition of 4.2 mg (0.05 mol.%) of Pd(OAc)2
the reaction mixture was heated to 130°C for 12 h. All
volatiles were then removed in vacuo and the residue
obtained was dissolved in 200 ml of a 1:1 ethanol–wa-
ter mixture. To this solution concentrated aqueous
solution of sodium hydroxide was added until the pH
value reached 12. The reaction mixture was extracted
with 100 ml of CH2Cl2 and the collected extracts were
washed with three aliquots of 10 ml of water. After
drying the organic phase over magnesium sulfate, the
solvent was evaporated in vacuo leaving 3d as a pale
yellow solid, which was dried at 20°C, 0.02 mbar. Due
to variable content of water no satisfying analytical
data could be obtained from 3d. Yield: 11.50 g (97%).
1H-NMR (d6-DMSO, l): 5.46 (NH2), 6.8–7.4 (arom.
H); 13C{1H}-NMR (d6-DMSO, l): 152.8; 151.3; 137.9
(J=11.2 Hz), 134.6 (J=21.4 Hz), 132.9 (J=19.3 Hz),
128.5, 128.4 (J=6.1 Hz), 125.6 (J=7.1 Hz), 123.3
(J=8.1 Hz); 31P{1H}-NMR (d6-DMSO, l): −6.1.
A total of 8.0 g (27.6 mmol) of 2c and 5.14 g (27.6
mmol) of diphenylphosphine was dissolved in 50 ml of
dimethylacetamide. Molecular oxygen dissolved in this
solution was thoroughly removed by repeated freeze–
thaw cycles. After addition of 6.2 mg (0.1 mol.%) of
Pd(OAc)2 the solution was heated to 130°C and stirred
for 12 h. Thereafter the reaction mixture was poured
into a solution of 5.70 g (35.0 mmol) of NH4PF6 in 300
ml of water. The precipitate formed was collected by
filtration on a Buchner funnel, washed with 50 ml of
water and dried in vacuo (20°C, 0.01 mbar). Yield: 13.1
g (96%) of the hexafluorophosphate of the cation in 3c.
A total of 5.0 g (10.1 mmol) of the hexafluorophos-
phate of the cation in 3c was dissolved in 20 ml of
ethanol. To this solution conc. aqueous NaOH was
added at 0°C until a pH value of about 12 was reached.
After addition of 10 ml of water the aqueous phase was
extracted with 50 ml of CH2Cl2, the organic phase was
separated and washed with five aliqots of 10 ml of
water. After addition of 11 ml of 1 N HCl to the
organic phase all volatiles were removed in vacuo
(20°C, 0.01 mbar). Yield: 3.35 g (80%) 3c. Crystals of
3c·CH3OH were precipitated on slow evaporation of a
methanolic solution of 3c.
7.3.2. Preparation of 4a and 4b
A total of 1.59 g (5.00 mmol) or 1.00 g (3.13 mmol)
of 4-diphenylphosphinophenyl guanidine 3d was dis-
solved in 10 ml of methanol or 5 ml of ethanol,
respectively. 0.415 g (5.00 mmol) of NH4H2PO2 or
0.683 g (3.13 mmol) of Ph2P(O)OH was added to these
solutions. On concentration of these solutions to about
half of their volume by evaporation of the solvent in
vacuo (and addition of 3 ml of ether in case of 4b) the
phosphines 4a and 4b precipitated out as colorless
solids, which were collected by filtration. 4a was further
purified by recrystallization from methanol. Yields: 1.72
g (89%) 4a, 1.32 g (78%) 4b.
3c.
Anal.
Found:
C,
63.51;
H,
6.89.
C21H23ClN3P·CH3OH (415.9). Calc.: C, 63.53; H,
1
6.54%. H-NMR (CD3OD, l): 7.82 (NH2), 9.52 (NH),
3.12 (NMe2), 7.1–7.6 (arom. H); 13C{1H}-NMR
(CD3OD, l): 155.5, 138.2, 137.0 (J=10.8 Hz), 135.1
(J=20.4 Hz), 133.8 (J=11.5 Hz), 133.7 (J=19.5 Hz),
129.6, 129.3 (J=6.9 Hz), 124.0 (J=7.4 Hz), 39.0
(CH3); 31P{1H}-NMR (CD3OD, l): −3.6; 15N{1H}-
NMR (CH3OH, CD3OD, l): −299.3 (NH), −281.4
(NH2), −303.8 (NMe2).

166
P. Machnitzki et al. / Journal of Organometallic Chemistry 602 (2000) 158–169
7.5. Synthesis of 5a–5d
the residue obtained was treated with 127 ml of a 1 N
HCl. After removal of the solvent in vacuo 5c was
obtained as a creme colored powder. Yield: 29.2 g
(91%). 5c.
5c. Anal. Found: C, 57.00; H, 6.90; N, 16.40.
C24H31Cl2N6P (505.4). Calc.: C, 57.03; H, 6.18; N,
16.63%. 13C{1H}-NMR (D2O, l): 157.8, 140.2 (J=9.2
Hz), 138.6 (J=8.1 Hz), 137.1 (J=7.2 Hz), 136.0 (J=
19.3 Hz), 133.9 (J=20.3 Hz), 132.6 (J=8.2 Hz), 132.1,
131.3 (J=7.1 Hz), 131.0 (J=18.3 Hz), 127.7, 40.5
(NMe2); 31P{1H}-NMR (D2O, l): −4.7.
7.5.1. Preparation of 5a
To the solution of 6.12 g (55.6 mmol) of phenylphos-
phine and 32.14 g (111.2 mmol) of 2d in 100 ml of
acetonitrile 0.26 g (0.2 mol.%) of Pd(PPh3)4 were added
after removal of molecular oxygen dissolved in this
solution by repeated freeze–thaw cycles. The reaction
mixture was heated under reflux for 40 h. After removal
of all volatiles in vacuo (60°C, 0.01 mbar) 5a was
obtained as pale yellow crystals. Yield: 37.7 g (98%).
Anal. Found: C, 41.94; H, 4.60; N, 12.36.
C24H31I2N6P (688.3). Calc.: C, 41.88; H, 4.54; N,
7.6. Synthesis of 5f
1
12.21%. H-NMR (d6-DMSO, l): 3.04 (NMe2), 7.11–
7.51 (arom. H); 13C{1H}-NMR (d6-DMSO, l): 155.8,
138.6 (J=13.2 Hz), 137.9 (J=9.2 Hz), 136.3 (J=11.2
Hz), 134.3 (J=20.1 Hz), 131.0 (J=18.3 Hz), 130.6
(J=6.1 Hz); 130.0, 129.6 (J=7.1 Hz), 128.9 (J=22.4
Hz), 125.2, 39.4 (NMe2); 31P{1H}-NMR (d6-DMSO,
l): −4.0.
A total of 21.3 g (71.6 mmol) of the 3-iodophenyl-
guanidinium chloride 1b, 3.9 g (35.8 mmol) of PhPH2
and 13.3 g (71.6 mmol) of nBu3N was dissolved in 120
ml of dimethylacetamide. Molecular oxygen dissolved
in the solution was removed by repeated freeze–thaw
cycles. Thereafter 41.2 mg (0.06 mol.%) of Pd2dba3 and
29.5 mg (0.2 mol.%) of DPPP dissolved in dimethylac-
etamide were added. The reaction mixture was heated
at 130°C for 2 days. Thereafter all volatiles were re-
moved in vacuo (100°C, 0.01 mbar), the remaining
residue was dissolved in 500 ml of water and the
aqueous solution was extracted with two portions of
100 ml of ether. Solid NaOH was added until the
solution showed a pH value of about 12. The precipi-
tate formed was extracted with three aliquots of 50 ml
of CH2Cl2. The collected extracts were washed with 60
ml of water and dried over MgSO4. After removal of
the solvent in vacuo a creme colored solid was left
which was dissolved in 90 ml of 1 N HCl. The aqueous
solution was evaporated to dryness and the solid ob-
tained was dissolved in ethanol and precipitated with
acetone. This procedure was repeated three times.
Yield: 8.06 g (50%).
7.5.2. Preparation of 5d
To the solution of 37.8 g (54.9 mmol) 5a in 120 ml of
water at 60°C conc. aqueous NaOH (4.40 g in 10 ml of
water) was added. The precipitate formed was dissolved
in 100 ml of CH2Cl2 and the aqueous phase was
extracted with a further aliquot of 100 ml of CH2Cl2.
The collected extractands were dried over MgSO4. Af-
ter evaporation of the solvents in vacuo (20°C, 20
mbar) 5d was obtained as a yellow powder. Yield: 21.9
g (84%).
Anal. Found: C, 60.88; H, 6.48. C24H29N6P·2.5H2O
1
(477.5). Calc.: C, 60.36; H, 7.17%. H-NMR (CDCl3,
l): 2.95 (NMe2), 4.1 (NH), 6.85–7.37 (arom. H);
13C{1H}-NMR (CDCl3 l): 152.7, 150.8 (J=7.1 Hz),
138.5 (J=11.2 Hz), 137.9 (J=11.2 Hz), 133.9 (J=19.3
Hz), 129.5 (J=8.1 Hz), 128.6 (J=20.2 Hz), 128.5
(J=12.2 Hz), 128.5, 128.5, 127.3 (J=19.3 Hz), 37.7
(NMe2); 31P{1H}-NMR (CDCl3, l): −2.9; MS: m/e
432 [M+].
Anal. Found: C, 52.45; H, 5.95; N, 15.20.
C20H23Cl2N6P·2C2H5OH (541.5). Calc.: C, 53.24; H,
6.52; N, 15.52%. 1H-NMR (D2O, l): 7.1–7.6, 3.63, 1.16
(C2H5OH); 13C{1H}-NMR (D2O, l): 155.2, 137.7 (J=
10.9 Hz), 134.3 (J=8.2 Hz), 134.0 (J=8.0 Hz), 133.1
(J=20.0 Hz), 131.8 (J=18.7 Hz), 129.7 (J=7.2 Hz),
129.3, 129.0 (J=3.0 Hz), 128.3 (J=7.5 Hz),
125.5;31P{1H}-NMR (D2O, l): −5.0; 15N{1H}-NMR
7.5.3. Preparation of 5b and 5c
To 21.9 g (31.8 mmol) of the guanidinium base 5d
suspended in 100 ml of water 15 ml of 48% HBr was
added. After all the solid material was dissolved, water
and excess HBr were removed in vacuo (20°C, 0.01
mbar). 5b was obtained as a creme colored hygroscopic
powder. Yield: 20.0 g (92%) 5b. Due to variable content
of water no satisfying analytical data could be
obtained.
4
(D2O, l): −283.8 (1J(NH)=91.8 Hz, NH; J(PN)=
2.1 Hz), 306.4 (1J(NH)=92 Hz, NH2).
7.7. Syntheses of the Pd(II) complexes 6 (cis, trans)
Potassium hydroxide was added to the solution of
43.6 g (63.3 mmol) of 5a in 350 ml of water. The
precipitate formed was dissolved in 100 ml of CH2Cl2.
The organic phase was separated and the aqueous
phase washed with three aliquots of CH2Cl2. The col-
lected organic phases were evaporated to dryness and
To a suspension of 0.21 g (0.55 mmol) of bis(ben-
zonitrile)palladium dichloride in 20 ml of water 0.56 g
(1.11 mmol) of 5c was added and the reaction mixture
was stirred for 1 h. The 31P{1H}-NMR spectrum of the
reaction mixture indicated that the complexes 6 had
been formed quantitatively. After filtration of the yel-

P. Machnitzki et al. / Journal of Organometallic Chemistry 602 (2000) 158–169
167
low solution through a fritted glass funnel all volatiles
7.9.2. Suzuki coupling reactions
were removed in vacuo (20°C, 0.01 mbar). The yellow
solid obtained was washed with 15 ml of toluene and 15
ml of ether. The residue was dissolved in 10 ml of
methanol and precipitated by addition of 5 ml of ether.
Yield: 1.3 g (99%).
A total of 0.54 g (1.5 mmol) of 10 [35], 0.62 g (4.5
mmol) of potassium carbonate and 0.22 g (1.6 mmol) of
p-tolueneboronic acid was dissolved in a two-phase
system consisting of 15 ml of toluene, 5 ml of
ethyleneglycol and 5.7 ml of water. After heating to
90°C, 4.3 ml of the catalyst solution was added. Sam-
ples were drawn periodically from the reaction mixture
and investigated by 31P{1H}-NMR spectroscopy.
6
(cis). Anal. Found: C, 46.97; H, 5.44.
C48H62Cl6N12P2Pd·2H2O (1224.2). Calc.: C, 47.09; H,
1
5.43%. H-NMR (D2O, l): 3.1 (NMe2), 7.2–7.9 (arom.
H); 13C{1H}-NMR (D2O, l): 157.5, 138.5 (N=14.2
Hz), 137.7 (N=12.7 Hz), 135.2 (N=135.2 Hz), 134.3
(N=10.2 Hz), 132.8 (N=57.5 Hz), 132.7 (N=12.7
Hz), 131.6 (N=13.7 Hz), 131.5 (N=13.2 Hz), 129.7,
128.6 (N=58.0 Hz), 40.6 (NMe2); 31P{1H}-NMR
(D2O, l): 35.9 (95%, cis), 28.8 (5%, trans).
7.9.3. Isolation of the coupling product 11
The toluene phases of the Suzuki coupling reactions
were collected and dried over magnesium sulfate. After
removal of the solvent in vacuo (20°C, 0.01 mbar) the
coupling product 11 was obtained as white solid.
11. Anal. Found: C, 81.07; H, 5.73. C25H21OP
6 (trans). 13C{1H}-NMR (CD3OD, l): 157.2, 137.9
(N=12.2 Hz), 136.2 (N=13.2 Hz), 134.0 (N=13.2
Hz), 132.8, 132.4 (N=48.8 Hz), 131.3 (N=13.2 Hz),
131.1 (N=11.4 Hz), 129.8 (N=12.2 Hz), 129.4 (N=
50.9 Hz), 128.2, 39.3 (NMe2); 31P{1H}-NMR (CD3OD,
l): 25.3.
1
(368.4). Calc.: C, 81.50; H, 5.74%. H-NMR (CDCl3,
l): 2.4 (CH3), 6.9–8.0 (arom. H); 13C{1H}-NMR
(CDCl3, l): 141.3 (J=11.2 Hz), 137.5, 136.9, 133.0
(J=103.7 Hz), 132.5 (J=103.8 Hz), 131.9 (J=10.3
Hz), 131.8 (J=2.0 Hz), 130.3 (J=18.9 Hz), 130.3
(J=2.0 Hz), 130.2 (J=5.8 Hz), 129.4, 128.7 (J=13.2
Hz), 128.4 (J=12.2 Hz), 126.9, 20.9 (CH3); 31P{1H}-
NMR (CDCl3, l): 30.6; MS: m/e=368 [M+], 277
[M+−C6H4−CH3].
7.8. Synthesis of the Mo(0) complex 9a
A total of 0.18 g (0.6 mmol) of a suspension of
cis-C7H8Mo(CO)4 in 10 ml of water was charged with
0.60 g (1.18 mmol) of 5c and the reaction mixture was
stirred at ambient temperature for 15 h. The yellow
solution obtained was filtered through a fritted glass
funnel and the filtrate was evaporated to dryness in
vacuo (20°C, 0.01 mbar). The residue was washed with
CH2Cl2 and ether and dried in vacuo. Yield:
quantitative.
Anal. Found: C, 50.01; H, 5.30. C52H62Cl4MoN12-
O4P2·2H2O (1254.9). Calc.: C, 49.77; H, 5.30%. 1H-
NMR (D2O, l): 3.00 (NMe2), 7.1–7.5 (arom. H);
13C{1H}-NMR (D2O, l): 217.4 (N=16.3 Hz), 212.2
(J=9.2 Hz), 157.6, 139.5 (N=32.5 Hz), 138.6 (N=
11.2 Hz), 136.4 (N=32.6 Hz), 135.9 (N=12.2 Hz),
133.2 (N=9.5 Hz), 133.1, 132.5 (N=8.6 Hz), 131.0
(N=9.5 Hz), 130.9 (N=15.3 Hz), 128.3, 40.5 (NMe2);
31P{1H}-NMR (D2O, l): 39.7.
7.10. X-ray structure analysis of 3c·CH3OH
Suitable single crystals of 3c·CH3OH for the X-ray
diffraction studies were grown by standard techniques
from a saturated methanolic solution of 3c. Preliminary
examination and data collection were carried out on a
Nonius CAD4 four circle diffractometer equipped with
a sealed tube (50 kV; 40 mA) and graphite monochro-
mated Mo–Ka radiation. Data collection were per-
formed at 193
K
within the
q
range of
1.75°BqB24.98°. The unit cell parameters were ob-
tained by full-matrix least-squares refinements of 25
accurately centered high angle reflections. A total num-
ber of 3807 reflections were collected. A total of 36
systematic absent reflections together with 266 negative
intensities were rejected from the original data set.
After merging (Rint=0.0471), a sum of 3251 indepen-
dent reflections remained and were used for all calcula-
tions. Data were corrected for Lorentz and polarization
effects. Within the measuring time three check reflec-
tions (120 h, monitored every 3600 s) indicated a loss of
48.6% of the initial intensity. A decay correction was
applied. The structure was solved by a combination of
direct methods and difference Fourier syntheses. All
‘heavy atoms’ of the asymmetric unit were refined
anisotropically. All hydrogen atoms were found and
refined with individual isotropic displacement parame-
ters. Full-matrix least-squares refinements were carried
out by minimizing Sw(F2o−Fc2)2 with SHELXL-93
weighting scheme [40] and stopped at R1=0.0602,
7.9. General procedure for the Suzuki coupling
reactions
7.9.1. In situ preparation of the Pd catalysts
To 20.0 mg (0.017 mmol) of Pd(Ph3P)4 dissolved in
10 ml of CH2Cl2 an aqueous solution of each 0.35
mmol of the ligands 5c (0.177 g), disulfonated diben-
zophosphole [24a] (0.174 g) or Ph2PꢀC6H4ꢀ4-PO3Na2
[24b] (0.135 g) was added. After stirring the two-phase
system for 1 h the yellow color of the organic phase had
dissappeared. The yellow aqueous phase was separated
and used for the catalysis experiments.

168
P. Machnitzki et al. / Journal of Organometallic Chemistry 602 (2000) 158–169
wR2=0.1518, and shift/err B0.001. The correct enan-
tiomere was confirmed by Flack’s parameter m=
0.10(13). Neutral atom scattering factors for all atoms
and anomalous dispersion corrections for the non-hy-
drogen atoms were taken from International Tables for
X-ray Crystallograpy [41]. All calculations were per-
formed on a DEC 3000 AXP workstation with the
STRUX-V [42] system, including the programs PLATON
[43], SHELXS-86 [44], and SHELXL-93 [45]. A summary
of the crystal and experimental data is reported in
Table 3.
Acknowledgements
This work was supported by the Bundesministerium
fu¨r Bildung, Wissenschaft, Forschung und Technologie.
The authors would like to thank Fonds der Chemischen
Industrie, Celanese GmbH and Aventis Research &
Technologies (Hoechst AG) for their financial support.
References
[1] D.J. Brauer, P. Machnitzki, T. Nickel, O. Stelzer, Eur. J. Inorg.
Chem. (2000) 65.
8. Supplementary material
[2] (a) B. Cornils, W.A. Herrmann, Applied Homogeneous Catalysis
with Organometallic Compounds, vol. 2, VCH, Weinheim, 1996,
p. 575. (b) W.A. Herrmann, C.W. Kohlpaintner, Angew. Chem.
105 (1993) 1588; Angew. Chem. Int. Ed. Engl. 32 (1993) 1524.
[3] E. Kuntz, Chemtech. 17 (1987) 570.
[4] (a) B. Mohr, D.M. Lynn, R.H. Grubbs, Organometallics 15
(1996) 4317. (b) G. Peiffer, S. Chhan, A. Bendayan, B. Waegell,
J.P. Zahra, J. Mol. Catal. 59 (1990) 1.
[5] R.T. Smith, M.C. Baird, Inorg. Chim. Acta 62 (1982) 135.
[6] (a) A. Heßler, O. Stelzer, H. Dibowski, K. Worm, F.P.
Schmidtchen, J. Org. Chem. 62 (1997) 2362. (b) H. Dibowski,
F.P. Schmidtchen, Angew. Chem. 110 (1998) 487; Angew. Chem.
Int. Ed. Engl. 37 (1998) 476. (c) K. Sonogashira, Y. Tohda, N.
Hagihara, Tetrahedron Lett. (1975) 4467.
Crystallographic data (excluding structure factors)
for the structure reported in this paper have been
deposited with the Cambridge Crystallographic Data
Centre as supplementary publication no. CCDC
143307. Copies of the data can be obtained free of
charge on application to CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK (fax: +44-1223-336033; e-mail:
deposit@ccdc.cam.ac.uk).
Table 3
Crystallographic data for 3c·CH3OH
[7] (a)Y. Yamamoto, S. Kojima, in: S. Patai, Z. Rappoport (Eds.),
The Chemistry of Amidines and Imidates, vol. 2, Wiley, New
York, 1991, p. 485. (b) M. Charton, J. Org. Chem. 30 (1965)
969. (c) P.J. Taylor, A.R. Wait, J. Chem. Soc. Perkin Trans. 2
(1986) 1765.
[8] (a) M.P. Fu¨lscher, E.L. Mehler, J. Mol. Struct. (Theochem.) 165
(1988) 319. (b) P.H. Boyle, A.P. Davis, K.J. Dempsey, G.D.
Hosken, J. Chem. Soc. Chem. Commun. (1994) 1875. (c) A.
Gleich, F.P. Schmidtchen, Chem. Ber. 123 (1990) 907.
[9] A. Heßler, M. Tepper, O. Stelzer, F.P. Schmidtchen, H. Di-
bowski, H. Bahrmann, M. Riedel (Hoechst AG), DE 197 01 245
(23/07/1998).
Chemical formula
Fw
Color/shape
Crystal size (mm)
Crystal system
Space group
C22H27ClN3OP
415.89
Colorless/fragment
0.50×0.50×0.10
Orthorhombic
P212121
,
a (A)
8.103(1)
,
b (A)
15.041(2)
18.308(2)
2231.3(5)
4
,
c (A)
3
,
V (A )
Z
T (K)
193
1.238
0.260
880
[10] (a) N. Miyaura, A. Suzuki, Chem. Rev. 95 (1995) 2457. (b) A.
Suzuki, Pure Appl. Chem. 63 (1991) 419.
[11] O. Herd, A. Heßler, M. Hingst, M. Tepper, O. Stelzer, J.
Organomet. Chem. 522 (1996) 69.
Dcalc (g cm−3
)
v (mm−1
F000
)
,
u (A)
0.71073
[12] O. Herd, A. Heßler, M. Hingst, P. Machnitzki, M. Tepper, O.
Stelzer, Catal. Today 42 (1998) 413.
[13] S. Berger, S. Braun, H.O. Kalinowski, NMR-Spektroskopie von
Nichtmetallen, vol. 3, 31P-NMR-Spektroskopie, Thieme, Stutt-
gart, 1993.
[14] (a) D.A. Baldwin, L. Denner, T.J. Egan, A.J. Markwell, Acta
Crystallogr. Sect. C 42 (1986) 1197. (b) J.M. Adams, R.W.H.
Small, Acta Crystallogr. Sect. B 30 (1974) 2191.
Device/scan method
q Range (°)
CAD4/v-scan
1.75–24.98
05h59, 05k517,
−215l521
3807
3251 (I\0)
3251 (I\0)
361
0.0471
0.0602
0.1518
1.100
Index ranges
No. reflections collected
No. independent reflections
No. observed reflections
No. parameters refined
Rint
[15] (a) D.P. Burum, R.R.J. Ernst, J. Magn. Reson. 39 (1980) 163.
(b) M.R. Bendall, D.M. Doddrell, D.T. Peg, J. Am. Chem. Soc.
103 (1981) 4603.
a
R1
b
wR2
[16] (a) H.O. Kalinowski, S. Berger, S. Braun, 13C-NMR SpeK-
troskopie, Thieme, Stuttgart, 1984, p. 199. (b) K.T. Leffek, P.
Pruszynski, K. Thanapaalasingham, Can. J. Chem. 67 (1989)
590.
GOF c
d
Weights a/b
Largest difference peak and hole
(e A
0.0794/3.0675
0.34/−0.39
−3
,
)
[17] D.G. Cameron, H.R. Hudson, M. Pianka, Phosphorus, Sulfur
Silicon 83 (1993) 21.
[18] K. Kanamori, J.D. Roberts, J. Am. Chem. Soc. 105 (1983) 4698.
[19] V. Schomaker, D.P. Stevenson, J. Am. Chem. Soc. 63 (1941) 37.
[20] E.G. Steward, D. Warner, G.R. Clarke, Acta Crystallogr. Sect.
B 30 (1974) 813.
a R1=S(ꢀꢀFoꢀ−ꢀFcꢀꢀ)/SꢀFoꢀ.
b wR2=[Sw(Fo2−Fc2)2/Sw(Fo2)2]1/2
.
c GOF=[Sw(F2o−Fc2)2/(No−Nv)]1/2
.
d w=1/[|2(F2o)+(aP)2+bP] with P: [max(0 or Fo2)+2F2c]/3.

P. Machnitzki et al. / Journal of Organometallic Chemistry 602 (2000) 158–169
169
[21] (a) C.L. Angell, N. Sheppard, A. Yamaguchi, T. Shimanouchi,
T. Miyazawa, S. Mizushima, Trans. Faraday Soc. 53 (1957) 589.
(b) D.J. Haas, D.R. Harris, H.H. Mills, Acta Crystallogr. 19
(1965) 676.
[22] (a) J.J. Daly, J. Chem. Soc. (A) (1964) 3799. (b) B.J. Dunne,
A.G. Orpen, Acta Crystallogr. Sect. C 47 (1991) 345.
[23] (a) C.A. Tolman, W.C. Seidel, D.H. Gerlach, J. Am. Chem. Soc.
94 (1972) 2669. (b) D.R. Coulson, Inorg. Synth. 13 (1972) 121.
[24] (a) O. Herd, P. Machnitzki, K. Wenz, O. Stelzer, to be pub-
lished. (b) P. Machnitzki, T. Nickel, O. Stelzer, C. Landgrafe,
Eur. J. Inorg. Chem. (1998) 1029. (c) F. Bitterer, O. Herd, A.
Heßler, M. Ku¨hnel, K. Rettig, O. Stelzer, W.S. Sheldrick, S.
Nagel, N. Ro¨sch, Inorg. Chem. 35 (1996) 4103.
[25] (a) R. Poilblanc, M. Bigorgne, Bull Soc. Chim. Fr. (1962) 1301.
(b) D.J. Darensbourg, C.J. Bischoff, Inorg. Chem. 32 (1993) 47.
[26] (a) G. Charlot, B. Tremillon, Chemical Reactions in Solvents
and Melts, Pergamon, Oxford, 1969, p. 274. (b) E.A. Moelwyn-
Hughes, Physical Chemistry, Pergamon, Oxford, 1961, pp. 301,
529.
[27] (a) A.W. Verstuyft, J.H. Nelson, Inorg. Chem. 14 (1975) 1501.
(b) D.A. Redfield, J.H. Nelson, Inorg. Chem. 12 (1973) 15.
[28] G. Balimann, H. Motschi, P.S. Pregosin, Inorg. Chim. Acta 23
(1977) 191.
[34] (a) S. Haber, N. Egger (Hoechst AG), WO 97/05151 (13/02/
1997). (b) S. Haber, J. Manero (Hoechst AG), EP 694.530
(31/01/1996).
[35] Obtained by oxidation of Ph2PꢀC6H4ꢀ3-Br (see Ref. [24b]) with
H2O2.
[36] (a) W. Gee, R.A. Shaw, B.C. Smith, Inorg. Synth. 9 (1967) 19.
(b) F. Pass, H. Schindlbaur, Monatsh. Chem. 90 (1959) 148.
[37] P.C. Crofts, in: G.M. Kosolapoff, L. Maier (Eds.), Organic
Phosphorus Compounds, vol. 6, Wiley, New York, 1972.
8
[38] W.P. Fehlhammer, W.A. Herrmann, K. Ofele, in: G. Brauer
(Ed.), Handbuch der Pra¨parativen Anorganischen Chemie, vol.
III, third ed., Ferdinand Enke Verlag, Stuttgart, 1981, p. 1799.
[39] (a) R. Pettit, J. Am. Chem. Soc. 81 (1959) 1266. (b) M.A.
Bennett, L. Pratt, G. Wilkinson, J. Chem. Soc. (1961) 2037. (c)
R.B. King, Inorg. Chem. 2 (1963) 936.
[40] G.M. Sheldrick, SHELXL Program System, University of Go¨ttin-
gen, Germany, 1993.
[41] A.J.C. Wilson (Ed.), International Tables for Crystallography,
vol. C, Tables 6.1.1.4 (pp. 500–502), 4.2.6.8 (pp. 219–222), and
4.2.4.2 (pp. 193–199), Kluwer, Dordrecht, The Netherlands,
1992.
[42] G. Artus, W. Scherer, T. Priermeier, E. Herdtweck, STRUX-V, A
Program System to Handle X-ray Data, TU Mu¨nchen, Ger-
many, 1997.
[43] A.L. Spek, PLATON-94–PLUTON-94, An Integrated Tool for the
Analysis of the Results of a Single Crystal Structure Determina-
tion, Acta Crystallogr. Sect. A 46 (1990) C34.
[29] S.O. Grim, R.L. Keiter, Inorg. Chim. Acta 4 (1970) 56.
[30] (a) T. Bartik, T. Himmler, J. Organomet. Chem. 293 (1985) 343.
(b) T. Bartik, B. Bartik, B.E. Hanson, I. Guo, I. Toth,
Organometallics 12 (1993) 164. (c) C. Larpent, H. Patin, Appl.
Organomet. Chem. 1 (1987) 529.
[44] G.M. Sheldrick, SHELXS-86, A Program for the Solution of
Crystal Structures from Diffraction Data, Acta Crystallogr. Sect.
A 46 (1990) 467.
[45] G.M. Sheldrick, SHELXL-93, in: G.M. Sheldrick, C. Kru¨ger, R.
Goddard (Eds.), Crystallographic Computing 3, Oxford Univer-
sity Press, UK, 1993, pp. 175–189.
[31] C.A. Tolman, Chem. Rev. 77 (1977) 313.
[32] (a) O. Stelzer, E. Unger, Chem. Ber. 108 (1975) 1246. (b) M.F.
Lappert, J.B. Pedlley, B.T. Wilkins, O. Stelzer, E. Unger, J.
Chem. Soc. Dalton Trans. (1975) 1207.
[33] T. Bartik, T. Himmler, H.G. Schulte, K. Seevogel, J.
Organomet. Chem. 272 (1984) 29.