Synthesis, coordination chemistry, and catalytic application of a novel unsymmetrical P/O ferrocenediyl ligand

Article abstract of DOI:10.1021/om0343768

A novel, unsymmetrical 1,1′-disubstituted ferrocenediyl ligand, 1-(diphenylphosphino)-1′-(methoxy)ferrocene (3), featuring phosphine and ether substituents has been synthesized via two different routes and structurally characterized. Its coordination chemistry was investigated by reaction with Rh(I), Cu(I), and group 10 metal precursors. With Ni(II) precursors, chelating complexes are formed in high yield, whereas with Pd(II) and Pt(II) precursors, either chelating complexes or monodentate bis ligand complexes with trans phosphorus ligation may be formed depending on the reaction conditions and metal precursor employed. A similar monodentate trans phosphorus-ligated complex is observed with Rh(I), whereas with Cu(I) precursors, a phosphorus-ligated monodentate bis ligand complex with a coordinated acetonitrile was obtained. Preliminary studies show that 3, in combination with either Pd(II) or Pd(0) precursors, can act as a catalyst for the Suzuki coupling reaction.

Full text of DOI:10.1021/om0343768

2744
Organometallics 2004, 23, 2744-2751
Syn th esis, Coor d in a tion Ch em istr y, a n d Ca ta lytic
Ap p lica tion of a Novel Un sym m etr ica l P /O F er r ocen ed iyl
Liga n d
Robert C. J . Atkinson, Vernon C. Gibson,* Nicholas J . Long,*
Andrew J . P. White, and David J . Williams
Department of Chemistry, Imperial College London, South Kensington,
London, SW7 2AZ U.K.
Received December 17, 2003
A novel, unsymmetrical 1,1′-disubstituted ferrocenediyl ligand, 1-(diphenylphosphino)-1′-
(methoxy)ferrocene (3), featuring phosphine and ether substituents has been synthesized
via two different routes and structurally characterized. Its coordination chemistry was
investigated by reaction with Rh(I), Cu(I), and group 10 metal precursors. With Ni(II)
precursors, chelating complexes are formed in high yield, whereas with Pd(II) and Pt(II)
precursors, either chelating complexes or monodentate bis ligand complexes with trans
phosphorus ligation may be formed depending on the reaction conditions and metal precursor
employed. A similar monodentate trans phosphorus-ligated complex is observed with Rh(I),
whereas with Cu(I) precursors, a phosphorus-ligated monodentate bis ligand complex with
a coordinated acetonitrile was obtained. Preliminary studies show that 3, in combination
with either Pd(II) or Pd(0) precursors, can act as a catalyst for the Suzuki coupling reaction.
In tr od u ction
in coordination chemistry22 are scarce: the tendency of
hydroxyferrocenes to decompose in air to cyclopentenone
species makes their synthesis and handling a challenge.
Ferrocenyl ethers, however, are generally more stable,
particularly if the isolation of a hydroxyferrocene in-
termediate is avoided. We have utilized recently devel-
oped synthetic methods in the synthesis of a 1,1′-
ferrocenediyl P/O ligand, which is described herein
Asymmetric, multidentate ligands that are hemilabile
in character have found numerous applications in
catalysis.1 Chelating ligands with a ferrocene backbone
are of particular interest, and extensive studies into
their coordination chemistry and applications have been
made.2,3 While hemilabile P/S,4 P/O,5-7 and N/O8 ligand
systems are well-known and important in catalysis,
examples of analogous 1,1′-disubstituted ferrocenes are
rare.9-17 We have recently demonstrated that the
unsymmetrical 1,1′-P/S ferrocenediyl ligand 1-(diphe-
nylphosphino)-1′-(methylthio)ferrocene (11) in combina-
tion with Pd2(dba)3 is an active catalyst system for the
Suzuki coupling reaction.18 Although hemilabile P/O
ferrocenyl ligands are rare, Buchwald et al. have shown
that 1-[2-(diphenylphosphino)ferrocenyl]ethyl methyl
ether, [(rac)-PPF-OMe], which has 1,2-unsymmetrical
substitution, in combination with Pd precursors can
catalyze the amination of aryl bromides, iodides, and
triflates.7,19 Ferrocenediyl compounds containing hy-
droxyl or ether substituents20,21 and their application
(6) Keim, W.; Kowaldt, F. H.; Goddard, R.; Kruger, C. Angew. Chem.,
Int. Ed. Engl. 1978, 17, 466. Hayashi, T.; Hayashizaki, K.; Kiyoi, T.;
Ito, Y. J . Am. Chem. Soc. 1988, 110, 8153. Mecking, S.; Keim, W.
Organometallics 1996, 15, 2650. Willoughby, C. A.; Duff, J .; Ronald
R.; Davis, W. M.; Buchwald, S. L. Organometallics 1996, 15, 472. Bei,
X.; Turner, H. W.; Weinberg, W. H.; Guram, A. S.; Petersen, J . L. J .
Org. Chem. 1999, 64, 6797. Bei, X.; Uno, T.; Norris, J .; Turner, H. W.;
Weinberg, W. H.; Guram, A. S.; Petersen, J . L. Organometallics 1999,
18, 1840. Weber, L.; Englert, U.; Ganter, B.; Keim, W.; Mothrath, M.
Chem. Commun. 2000, 1419. Komon, Z. J . A.; Bu, X.; Bazan, G. C. J .
Am. Chem. Soc. 2000, 122, 1830. Heinicke, J .; He, M.; Dal, A.; Klein,
H.-F.; Hetche, O.; Keim, W.; Florke, U.; Haupt, H.-J . Eur. J . Inorg.
Chem. 2000, 431. Gibson, V. C.; Tomov, A.; White, A. J . P.; Williams,
D. J . Chem. Commun. 2001, 719. Soula, R.; Broyer, J . P.; Llauro, M.
F.; Tomov, A.; Spitz, R.; Claverie, J .; Drujon, X.; Malinge, J .; Saude-
mont, T. Macromolecules 2001, 34, 2438. Gilbertson, S. R.; Lan, P. Org.
Lett. 2001, 2, 2237. Han, J . W.; Tokunaga, N.; Hayashi, T. J . Am.
Chem. Soc. 2001, 123, 12915. Liu, W.; Malinoski, J . M.; Brookhart,
M. Organometallics 2002, 21, 2836. Carter, A.; Cohen, S. A.; Cooley,
N. A.; Murphy, A.; Scutt, J .; Wass, D. F. Chem. Commun. 2002, 858.
Drent, E.; van Dijk, R.; van Ginkel, R.; van Oort, B.; Pugh, R. I. Chem.
Commun. 2002, 744. Drent, E.; van Dijk, R.; van Ginkel, R.; van Oort,
B.; Pugh, R. I. Chem. Commun. 2002, 964.
* Corresponding authors. (N.J .L.) Tel: +44 (0)20 7594 5781. Fax:
+44 (0)20 7594 5804. E-mail: n.long@imperial.ac.uk.
(1) Slone, C. S.; Weinberger, D. A.; Mirkin, C. A. Prog. Inorg. Chem.
1999, 48, 233.
(2) (a) For a detailed literature review, see: Ferrocenes: Homoge-
neous Catalysis-Organic Synthesis-Materials Science; Togni, A.,
Hayashi, T., Eds.; VCH: Weinheim, Germany, 1995. (b) Metallocenes;
Togni, A., Haltermann, R. L., Eds.; Wiley-VCH: Weinheim, Germany,
1998.
(3) For a comprehensive overview of ferrocene and other metallocene
chemistry see: Long, N. J . Metallocenes: An Introduction to Sandwich
Complexes; Blackwell Science: Oxford, 1998.
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Rev. 2000, 108, 89.
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10.1021/om0343768 CCC: $27.50 © 2004 American Chemical Society
Publication on Web 04/27/2004

Unsymmetrical P/ O Ferrocenediyl Ligand
Organometallics, Vol. 23, No. 11, 2004 2745
Sch em e 1. Syn th esis of Liga n d 3a
varying the amounts of acetic acid and copper(I) oxide
and the length of time of reflux, but the maximum yield
was always low. A slight improvement in yield was
found when the acetic acid was diluted with acetonitrile
and added dropwise over a long period of time to help
promote monosubstitution. A possible reaction mecha-
nism, proposed by Sato et al.,26 suggests that the
association of copper to the ligand through the bromine
and acetate moieties might favor di-substitution, as
after one substitution reaction has taken place, the
copper center is correctly positioned to catalyze the
a
1
Reagents and conditions: (i) AcOH, Cu2O cat., MeCN,
substitution of the other bromine atom. The H NMR
reflux, 15 h. (ii) NaH, 15-crown-5, MeI, THF, rt, 15 h. (iii)
n-BuLi, THF, -25 °C, 30 min; TMSOOTMS, -78 °C, 1 h;
Me2SO4, K2CO3, acetone, reflux, 20 h. (iv) n-BuLi, THF, -78
°C, 10 min; ClPPh2, rt, 20 h.
spectrum of 1 shows a singlet corresponding to the
methyl group of the acetate. The cyclopentadienyl
protons show four pseudo-triplets confirming the un-
symmetrical substitution. Reduction of 1 with sodium
hydride in the presence of 15-crown-5 and iodomethane
yielded 1-(bromo)-1′-(methoxy)ferrocene (2).21 The 1H
NMR spectrum of 2 shows a singlet corresponding to
the methyl group of the ether: the proximity to the
electronegative oxygen substituent causes a downfield
shift compared to 1. Again, the cyclopentadienyl protons
show four pseudo-triplets. The disappointingly low yield
of 2 via this route (overall 10% from 1,1′-dibromofer-
rocene) led us to search for a higher yielding alternative.
together with a study of its coordination chemistry and
catalytic efficacy in the Suzuki coupling reaction, high-
lighting the different properties imparted by an ethers
compared to a thioetherssubstituent (as in 11). We have
recently formed two novel anionic 1,1′-ferrocenediyl P/O
ligands,23 and we now report the first example of a
neutral 1,1′-unsymmetrical P/O ferrocenediyl ligand.
Resu lts a n d Discu ssion
The use of bis(trimethylsilyl)peroxide27 in the prepa-
ration of aryl trimethylsilyl ethers,28 ferrocenyl tri-
methylsilyl ethers,29 and ferrocenyl hydroxide deriva-
tives30 (via hydrolysis) prompted its application in the
synthesis of 2. 1,1-Dibromoferrocene was reacted with
1 equiv of n-butyllithium in a cooled THF solution,
followed by addition of bis(trimethylsilyl)peroxide. After
the reaction mixture had been stirred for 1 h at room
temperature, the solvent was removed in vacuo and the
residue was redissolved in nitrogen-saturated acetone.
Potassium carbonate (to catalyze removal of the tri-
methylsilyl protecting group) was added, followed by an
excess of dimethyl sulfate.31 After refluxing for 24 h,
purification was effected via column chromatography to
form 2 in a 56% yield from 1,1-dibromoferrocene.
Liga n d Syn th esis. Ligand 3 has been synthesized
via two different routes from 1,1′-dibromoferrocene
(Scheme 1). Sato et al. have reported the synthesis of
1-(bromo),1′-(stearyloxy)ferrocene, which was achieved
by the reaction of 1,1′-dibromoferrocene with stearic acid
in the presence of copper(I) oxide in refluxing acetoni-
trile. (It should be noted that the yield of this reaction
was only 13% due to the additional formation of 1,1′-
bis(stearyloxy)ferrocene.)24 In our work, 1-(bromo)-1′-
(acetoxy)ferrocene (1) was synthesized in 13% yield by
the reaction of 1,1′-dibromoferrocene25 with acetic acid
in the presence of copper(I) oxide in refluxing acetoni-
trile. This reaction is also low yielding due to the
formation of 1,1′-bis(acetoxy)ferrocene as a byproduct.
Attempts were made to optimize the yield of 1 by
The conversion of 2 to 3 was completed via the
addition of 1 equiv of n-butyllithium to a cooled THF
solution of 2, followed by quenching with chlorodiphe-
(11) Deng, W.-P.; Hou, X.-L.; Dai, L.-X.; Yu, Y.-H.; Xia, W. Chem.
Commun. 2000, 285. Deng, W.-P.; Hou, X.-L.; Dai, L.-X.; Dong, X.-W.
Chem. Commun. 2000, 1483.
(12) Long, N. J .; Martin, J .; Opromolla, G.; White, A. J . P.; Williams,
D. J .; Zanello, P. J . Chem. Soc., Dalton Trans. 1999, 1981.
(13) Gibson, V. C.; Long, N. J .; White, A. J . P.; Williams, C. K.;
Williams, D. J . Chem. Commun. 2000, 2359.
(14) Gibson, V. C.; Long, N. J .; White, A. J . P.; Williams, C. K.;
Williams, D. J . Organometallics 2002, 21, 770.
(15) Broussier, R.; Bentabet, E.; Laly, M.; Richard, P.; Kuz’mina,
L. G.; Serp, P.; Wheatley, N.; Kalck, P.; Gautheron, B. J . Organomet.
Chem. 2000, 613, 77.
1
nylphosphine. The H spectrum of 3 again shows four
pseudo-triplets for the cyclopentadienyl protons together
with signals due to the methyl and phenyl groups. The
31P{1H} spectrum shows a singlet at -16.4 ppm. Crys-
tals of 3 were obtained by slow evaporation from a
pentane solution. A single-crystal X-ray analysis showed
the complex (Figure 1) to have a gross structure very
similar to those of the related unsubstituted,32 carbox-
(16) Balavoine, G. G. A.; Daran, J .-C.; Iftime, G.; Manoury, E.;
Moreau-Bossuet, C. J . Organomet. Chem. 1998, 567, 191.
(17) Adeleke, J . A.; Chen, Y.-W.; Liu, L.-K. Organometallics 1992,
11, 2543.
(18) Gibson, V. C.; Long, N. J .; White, A. J . P.; Williams, C. K.;
Williams, D. J .; Fontani, M.; Zanello, P. Dalton 2002, 3280.
(19) Wolfe, J . P.; Buchwald, S. L. Tetrahedron Lett. 1997, 38, 6359.
(20) Nesmeyanov, A. N.; Sazonova, V. A.; Drozd, V. N.; Nikonova,
L. A. M. V. Dokl. Akad. Nauk SSSR 1960, 133, 126.
(21) Akabori, S.; Sato, M.; Ebine, S. Synthesis 1981, 278.
(22) Akabori, S.; Kumagai, T.; Shirahige, T. Organometallics 1987,
6, 2105. Sato, M.; Sekino, M.; Katada, M.; Akabori, S. J . Organomet.
Chem. 1989, 377, 327. Allgeier, A. M.; Singewald, E. T.; Mirkin, C. A.;
Stern, C. L. Organometallics 1994, 13, 2928.
(26) Sato, M.; Motoyama, I.; Hata, K. Bull. Chem. Soc. J pn. 1970,
43, 2213.
(27) Cookson, P. G.; Davies, A. G.; Fazal, N. J . Organomet. Chem.
1975, 99, C31.
(28) Taddei, M.; Ricci, A. Synthesis 1986, 633.
(29) Herberhold, M.; Brendel, H.-D.; Hofmann, A.; Hofmann, B.;
Milius, W. J . Organomet. Chem. 1998, 536, 173.
(30) Pickett, T. E.; Richards, C. J . Tetrahedron: Asymmetry 1999,
10, 4095. Riant, O.; Samuel, O.; Flessner, T.; Taudien, S.; Kagan, H.
B. J . Org. Chem. 1997, 62, 6733. Lagneau, N. M.; Chen, Y.; Robben,
P. M.; Sin, H.-S.; Takasu, K.; Chen, J .-S.; Robinson, P. D.; Hua, D. H.
Tetrahedron 1998, 54, 7301.
(23) Atkinson, R. C. J .; Gibson, V. C.; Long, N. J .; White, A. J . P.;
Williams, D. J . Dalton, in press.
(24) Sato, M.; Nakahara, H.; Fukuda, K.; Akabori, S. J . Chem. Soc.,
Chem. Commun. 1988, 24.
(25) Shafir, A.; Power, M. P.; Whitener, G. D.; Arnold, J . Organo-
metallics 2000, 19, 3978.
(31) Freskos, J . N.; Morrow, G. W.; Swenton, J . S. J . Org. Chem.
1985, 50, 805.
(32) Adeleke, J . A.; Liu, L.-K. Acta Crystallogr. Sect. C 1993, 49,
680.

2746 Organometallics, Vol. 23, No. 11, 2004
Atkinson et al.
Sch em e 2. Syn th esis of Gr ou p 10 Meta l
Com p lexes of 3a
F igu r e 1. Molecular structure of 3. Selected bond lengths
(Å) and angles (deg): P-C(10) 1.814(3), P-C(17) 1.851(2),
P-C(23) 1.857(2), C(10)-P-C(17) 101.62(10), C(10)-P-
C(23) 101.40(11), C(17)-P-C(23) 100.32(10).
a
Reagents and conditions: (i) (DME)NiBr2, CH2Cl2, 35 °C,
24 h. (ii) (PhCN)2PtCl2, toluene/CH2Cl2, rt, 20 h. (iii)
(COD)PdCl2, toluene/CH2Cl2, rt, 20 h.
aldehyde,33 carboxylic acid,34 and mercapto,14 diphe-
nylphosphino analogues. In all of these complexes one
of the P-Ph bonds is oriented approximately orthogo-
nally (ca. 88°) to the plane of its associated C5H4 ring,
while the other is inclined by ca. 15° and angled upward
toward the other cyclopentadienyl ring. The relative
orientations of the substituents on the two Cp rings
appear to be controlled by either intra- or intermolecular
interactions. In 3 the cyclopentadienyl rings are inclined
by ca. 2° and staggered by ca. 16°, there being a
relatively short (2.53 Å) approach of C(18)-H to the
methoxy oxygen atom. The angles at phosphorus are all
contracted from tetrahedral but do not differ signifi-
cantly from those observed in, for example, the unsub-
stituted analogue.32 The P-Ph bond lengths in 3 are
longer than those in the unsubstituted,32 carboxalde-
hyde,33 and carboxylic acid34 structures but the same
as those in the mercapto complex.14 The P-Cp distance
is the same in all of these structures. The only short
intermolecular contact of note is between C(8)-H and
the C(23) phenyl ring in centrosymmetrically related
pairs of molecules; the H‚‚‚π distance is 2.87 Å and the
C-H‚‚‚π angle 163°.
Coor d in a tion Ch em istr y. To probe the coordination
chemistry of 3, the ligand was reacted with group 10
metal precursors as shown in Scheme 2. The Ni(II)
complex 4 was obtained via the reaction of (1,2-
dimethoxyethane)dibromonickel(II) and 3 in CH2Cl2.
The reaction mixture changed color immediately from
pale pink to dark green and was stirred at 35 °C for 24
h, after which time a green precipitate was visible. The
solvent was removed in vacuo and the green powder
washed with dry hexane. The 1H NMR showed very
broad peaks and could not be properly assigned. The
31P{1H} NMR showed a single peak at 29.8 ppm. The
broadening of the NMR suggested that the complex was
paramagnetic, which is consistent with a tetrahedral
geometry at the Ni center. The positive ion FAB mass
spectrum did not show the molecular ion but instead a
peak for the free ligand (400 amu). However, the
microanalysis is consistent with a 1:1 chelate complex.
A similar result was obtained upon the reaction of 11
with (1,2-dimethoxyethane)dibromonickel(II).18 The Pd-
(II) complex 5 was obtained upon the reaction of
dichloro(1,5-cyclooctadiene)palladium(II) dissolved in
CH2Cl2 with a slight excess of 3 dissolved in toluene.
The solution was stirred at room temperature for 20 h,
by which time a brown precipitate was visible. The
precipitate was filtered and washed with hexane to
remove any unreacted ligand, enabling isolation of
dichloro[1-(diphenylphosphino)-1′-(methoxy)ferrocene]-
1
palladium(II) (5) in 70% yield. The H NMR spectrum
shows a singlet at 3.71 ppm corresponding to the
methoxy group. The peak is shifted downfield compared
to the free ligand due to coordination of the oxygen to
the metal center. The cyclopentadienyl protons show
two poorly resolved multiplets at 4.53 and 4.60 ppm,
and the phenyl protons of the PPh2 group give a
multiplet centered at 7.45 ppm. The 31P{1H} NMR
shows a singlet at 31.9 ppm and indicates a considerable
downfield shift compared to the free ligand due to the
coordination of the phosphorus to the metal center. The
FAB mass spectrum exhibits the molecular ion (578
amu) and the expected fragmentation pattern corre-
sponding to the loss of one chlorine (543 amu) and two
chlorines (506 amu).
An investigation into the coordination chemistry of 3
with Pt(II) precursors was also undertaken. A slight
excess of ligand 3 in toluene was stirred at room
temperature with Pt(PhCN)2Cl2 in DCM for 20 h in an
attempt to synthesize a chelating complex. Instead,
however, the platinum complex 6 with two monodentate
ligands bound through their phosphorus atoms was
detected as shown in Scheme 2. The yield of the complex
was only 35%. This was improved by using 2 equiv of
ligand to ensure that all of the metal precursor reacts.
A similar result was obtained by Long et al., who
synthesized bis[1-(diphenylphosphino)-1′-(methylsulfa-
nyl)ferrocene]palladium(II) dichloride by stirring 3 equiv
of 1-(diphenylphosphino)-1′-(methylsulfanyl)ferrocene
with Pd(COD)Cl2 at room temperature.18
1
The H NMR spectrum gives a singlet at 3.57 ppm
corresponding to the methoxy group. This is very similar
to the chemical shift of the methoxy group in the free
ligand, which is 3.52 ppm, indicating that the oxygen
is not bound to the metal center. The cyclopentadienyl
(33) Stepnicka, P.; Base, T. Inorg. Chem. Commun. 2001, 4, 682.
(34) Podlaha, J .; Stepnicka, P.; Ludvik, J .; Cisarova, I. Organome-
tallics 1996, 15, 543.

Unsymmetrical P/ O Ferrocenediyl Ligand
Organometallics, Vol. 23, No. 11, 2004 2747
inclined by ca. 5°. The P-C5 and O-C5 vectors have a
gauche (67°) relationship. The closest intramolecular
approach to the methoxy oxygen atom is 2.57 Å from
C(22)-H. There are no noteworthy intermolecular
interactions.
A slight excess of 3 in toluene was refluxed with both
Pt(PhCN)2Cl2 and Pt(COD)Cl2 in CH2Cl2 for 20 h in a
further attempt to synthesize a chelating complex. It
was hoped that the harsher conditions would favor
formation of the desired complex. The solution was
concentrated and dry hexane added to bring about
precipitation of the products. The mixture was filtered
and the residue washed with dry hexane. Analysis of
the resulting orange powder showed it to be a mixture
of chelating and nonchelating complexes. The FAB mass
spectrum has a peak corresponding to both the molec-
ular ion of dichloro[1-(diphenylphosphino)-1′-(methoxy)-
ferrocene]platinum(II), 7 (666 amu), and the molecular
ion of 6 (1066 amu). The 1H NMR spectrum shows a
peak at 3.70 ppm corresponding to the methoxy group
of 7 (shifted downfield from the free ligand at 3.52 ppm
due to the coordination of the oxygen to the metal), as
well as a peak at 3.57 ppm corresponding to the methoxy
group of 6. The ferrocene and phenyl regions could not
be fully resolved due to overlapping of the peaks from
both complexes. Separation of the two complexes was
attempted by both recrystallization and preparative
TLC. Recrystallization was not successful, as both
complexes precipitated as microcrystalline powders on
layering a CH2Cl2 solution of the mixture with hexane.
Compound 6 was isolated via preparative TLC, but
unfortunately 7 decomposed on the TLC plates and
could not be isolated. It should be noted that a similar
result was obtained when a slight excess of 3 was heated
to 35 °C with Pd(PhCN)2Cl2 in benzene for 20 h.
Analysis of the reaction mixture showed it to contain a
mixture of 5 and bis[1-(diphenylphosphino)-1′-(meth-
oxy)ferrocene]palladium(II) chloride (8). The FAB mass
spectrum has a peak corresponding to the molecular ion
of both 5 (578 amu) and 8 (978 amu). The 1H NMR
spectrum shows a peak at 3.71 ppm corresponding to
the methoxy group of 5 together with a peak at 3.55
ppm due to the methoxy group of 8, indicating the
oxygen heteroatom is not bound to the Pd center. The
31P{1H} NMR gives a peak at 15.8 ppm corresponding
to 8 and at 31.9 ppm due to 5.
F igu r e 2. Molecular structure of 6.
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Com p ou n d 6
Pt-Cl
P-C(5)
P-C(23)
2.3121(13)
1.815(7)
1.849(3)
Pt-P
P-C(17)
2.3216(14)
1.827(3)
Cl-Pt-Cl′
180
Cl-Pt-P
87.32(7)
180
103.0(3)
114.2(2)
120.4(2)
Cl-Pt-P′
92.68(7)
105.9(2)
102.4(2)
109.5(2)
P-Pt-P′
C(5)-P-C(17)
C(17)-P-C(23)
C(17)-P-Pt
C(5)-P-C(23)
C(5)-P-Pt
C(23)-P-Pt
protons show a multiplet at 4.28 ppm (due to the
presence of two overlapping pseudo-triplets) and pseudo-
triplets at 4.45 and 4.59 ppm. The phenyl protons of the
PPh2 group give a multiplet centered at 7.38 ppm. The
31P{1H} NMR exhibits only one singlet at 11.0 ppm
(indicating that only one isomer of the product formed,
later identifed as the trans-isomer by crystal structure
1
analysis). Platinum satellites are observed with a J Pt-P
of 2620 Hz. The 13C{1H} NMR shows six signals for the
cyclopentadienyl carbons together with signals due to
the methyl and phenyl carbons. The ipso, ortho, and
meta phenyl carbons show coupling to the 31P nucleus
but appear as triplets rather than the expected doublets.
It is postulated that the carbons on different phenyl
rings are in slightly different environments, and hence
the pseudo-triplets result from two overlapping dou-
blets. The FAB mass spectrum shows the molecular ion
(1066 amu) and the expected fragmentation pattern
corresponding to the loss of one chlorine atom (1030
amu) and two chlorines (995 amu).
A Rh(I) complex 9 was formed by dissolving 2 equiv
of 3 in the minimum amount of diethyl ether and adding
this to a solution of tetracarbonyldichlorodirhodium(I)
dissolved in methanol (Scheme 3). An orange precipitate
formed after 5 min, which was filtered off after 2 h and
washed with diethyl ether and methanol. Rather than
the expected chelating complex, bis[1-(diphenylphos-
phino-κP)-1′-(methoxy)ferrocene]carbonylchlororhodium-
(I) (9) was isolated in 47% yield. A similar monodentate
bis ligand Rh(I) complex with trans phosphorus ligation
featuring a P/O-substituted ligand has recently been
used in methanol carbonylation catalysis,37 and the
application of 9 in carbonylation catalysis is currently
under study. The 1H NMR spectrum of 9 shows a singlet
at 3.52 ppm corresponding to the methoxy protons,
The complex 6, which is illustrated in Figure 2, has
crystallographic inversion symmetry and is isomorphous
with its [(methylsulfanyl)ferrocene]palladium(II) ana-
logue.18 The geometry at platinum is slightly distorted
square planar with cis angles of 92.68(7)° and 87.32-
(7)°; the Pt-P bond lengths (Table 1) do not differ
significantly from those in, for example, the analogous
unsubstituted35 and carboxylic acid36 bis-complexes. As
observed in 3, one of the P-Ph bonds lies close (ca. 9°)
to the plane of its associated Cp ring, while the other is
steeply inclined (by ca. 77°). The cyclopentadienyl rings
are virtually eclipsed (ca. 2° stagger) with their planes
(35) (a) Otto, S.; Roodt, A. Acta Crystallogr. Sect. C 1997, 53, 1414.
(b) Long, N. J .; White, A. J . P.; Williams, D. J .; Younus, M. J .
Organomet. Chem. 2002, 649, 94.
(36) Stepnicka, P.; Podlaha, J .; Gyepes, R.; Polasek, M. J . Orga-
nomet. Chem. 1998, 552, 293.
(37) Dutta, D. K.; Woollins, J . D.; Slawin, A. M. Z.; Konwar, D.; Das,
P.; Sharma, M.; Bhattacharyya, P.; Aucott, S. M. Dalton 2003, 2674.

2748 Organometallics, Vol. 23, No. 11, 2004
Atkinson et al.
Sch em e 3. Syn th esis of Rh (I) a n d Cu (I)
Com p lexes of 3a
F igu r e 3. Molecular structure of 10.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Com p ou n d 10
Cu-P(1)
2.2530(13)
1.969(5)
1.824(3)
1.803(5)
1.838(2)
Cu-P(2)
2.2491(13)
1.802(5)
1.838(3)
1.826(3)
a
Reagents and conditions: (i) [RhCl(CO)2]2, methanol/Et2O,
Cu-N(50)
P(1)-C(17)
P(2)-C(24)
P(2)-C(46)
P(1)-C(1)
P(1)-C(23)
P(2)-C(40)
rt, 2 h. (ii) Cu(MeCN)4+PF6-, CH2Cl2, rt, 2 h.
barely shifted from the free ligand, indicating that the
oxygen heteroatom is not interacting with the rhodium
center. The ferrocenyl protons give signals at 4.12, 4.21,
and 4.48 ppm. The phenyl groups exhibit two multiplets
at 7.39 and 7.66 ppm. The 31P{1H} NMR spectrum
shows a doublet at 22.74 ppm due to coupling with the
N(50)-Cu-P(2)
P(2)-Cu-P(1)
C(1)-P(1)-C(23)
C(1)-P(1)-Cu
C(23)-P(1)-Cu
C(24)-P(2)-C(46) 103.01(18) C(40)-P(2)-C(46) 103.26(17)
C(24)-P(2)-Cu
C(46)-P(2)-Cu
116.81(14) N(50)-Cu-P(1)
125.87(5) C(1)-P(1)-C(17)
103.21(19) C(17)-P(1)-C(23) 102.65(16)
118.82(18) C(17)-P(1)-Cu 112.02(11)
113.75(13) C(24)-P(2)-C(40) 102.6(2)
116.98(14)
104.7(2)
1
Rh nucleus, and the coupling constant J Rh-P is 125.8
116.99(17) C(40)-P(2)-Cu
112.95(12)
116.16(12)
Hz. This is lower than the value of 168 Hz found for
carbonylchloro[1-(diphenylphosphino)-1′-(methylthio)-
ferrocene]rhodium(I)18 and is expected as two P nuclei
now couple to the Rh center. The fact that there is only
one P environment suggests that the P atoms are trans
to each other and that the complex has a similar trans
phosphorus ligation to 6. The 13C{1H} NMR shows six
signals for the cyclopentadienyl carbons together with
signals due to the methyl and phenyl carbons. The ipso,
ortho, and meta phenyl again appear as triplets rather
than the expected doublets as with 6. The carbonyl
carbon shows a triplet at 135.96 ppm due to coupling
to the two equivalent 31P nuclei, but coupling to the
103Rh nucleus was not observed due to the broad nature
of the signals. Only one carbonyl peak is seen in the IR
spectrum at 1968 cm-1. This is lower than the value of
2006 cm-1 found for carbonylchloro[1-(diphenylphos-
phino)-1′-(methylthio)ferrocene]rhodium(I), as the Rh
center has two phosphine donor groups resulting in
more back-donation to the CO π* orbitals. The positive
ion FAB mass spectrum shows the molecular ion (966
amu) and fragmentation peaks due to M+ - Cl (931
amu) and M+ - CO - Cl (903 amu). A copper(I)
complex, 10, was also synthesized as an analogue to the
spiro Cu(I) complexes of 11 previously synthesized.12
Two equivalents of 3 were dissolved in dry DCM and
added to a stirred DCM solution of Cu(MeCN)4+(PF6)-.
The reaction mixture was stirred for 2 h and the solvent
evaporated. The orange precipitate thus formed was
washed with hexane and dried. The 1H NMR of 10
shows a singlet at 2.37 ppm, showing that bound MeCN
is still present in the product complex. The methoxy
protons give a singlet at 3.45 ppm; surprisingly this
represents an upfield shift from the free ligand, again
suggesting that the O heteroatom is not coordinated to
the Cu atom. The ferrocenyl protons exhibit four signals
at 3.60, 3.95, 4.10, and 4.51 ppm, and the phenyl protons
show a multiplet centered at 7.34 ppm. The 31P{1H}
NMR exhibits a singlet at -6.44 ppm corresponding to
the P donor atom in the ligand and a septet at -143.64
ppm corresponding to the PF6- counterion. The positive
ion FAB mass spectrum does not give the molecular ion
but the expected fragmentation pattern corresponding
to M+ - MeCN (863 amu) and M+ - MeCN - L (463
amu), as well as a signal for L+ (400 amu).
The molecular structure of 10 confirmed the presence
of a coordinated acetonitrile and showed the geometry
at copper to be distorted trigonal planar (Figure 3, Table
2), the other two coordination sites being occupied by
the phosphorus atoms of two independent 1-(diphe-
nylphosphino)-1′-(methoxy)ferrocene ligands. The Cu-P
bond lengths [2.2491(13) and 2.2530(13) Å] are compa-
rable with those observed in other Cu(I)P2NCMe com-
plexes,38 but the Cu-N distance [1.969(5) Å] is notice-
ably shorter than the range of values (1.998-2.038 Å)
observed in those complexes. The copper atom is dis-
placed by 0.073 Å out of the plane of its substituents in
(38) (a) Che, C.-M.; Mao, Z.; Miskowski, V. M.; Tse, M.-C.; Chan,
C.-K.; Cheung, K.-K.; Phillips, D. L.; Leung, K.-H. Angew. Chem., Int.
Ed. 2000, 39, 4084. (b) Liu, H.; Calhorda, M. J .; Drew, M. G. B.; Felix,
V.; Novosad, J .; Veiros, L. F.; de Biani, F. F.; Zanello, P. Dalton 2002,
4365.

Unsymmetrical P/ O Ferrocenediyl Ligand
Organometallics, Vol. 23, No. 11, 2004 2749
Sch em e 4. Rea gen ts a n d Con d ition s for Ca ta lyst
Testin g of th e Su zu k i Rea ction
the experimental conditions described here, dppf and
11 were found to have a similar activity, with 3 slightly
higher than both.
Con clu sion s
The synthesis of the novel ligand 3 has been reported
via two different routes, which include a new route to
unsymmetrical ferrocenyl ethers. The relatively straight-
forward, highest yielding route affords 3 in an overall
yield of 23% from 1,1′-dibromoferrocene. The coordina-
tion chemistry of 3 has been explored with group 10
metal halides and Rh(I) and Cu(I) precursors, and
chelating complexes were isolated with (COD)PdCl2 and
(dme)NiBr2. A monodentate bis ligand complex with
trans phosphorus ligation was isolated with Pt(Ph-
CN)2Cl2. With Pd(PhCN)2Cl2, evidence was found for the
analogous Pd complex, which was formed alongside a
chelating complex. Both chelating and phosphorus li-
gated bis ligand complexes were formed with Pt(COD)-
Cl2. Similar phosphorus ligated bis ligand complexes
were formed with Rh(I) and Cu(I) precursors. The
coordination chemistry described herein suggests that
3 may be able to act as a hemilabile ligand with the
methoxy group acting as substitutionally labile with soft
metal centers, and future studies will focus on the
applications of 3 in catalysis together with further study
into the coordination chemistry of this ligand. Prelimi-
nary studies into the efficacy of 3, in combination with
Pd precursors, as a catalyst for the Suzuki reaction show
that 3 is a good ligand for this reaction. The synthesis
of other 1,1′-unsymmetrical P/O, S/O, and N/O fer-
rocenediyl ligands is currently underway.
Ta ble 3. Resu lts of Ca ta lysis Testin g for th e
Su zu k i Rea ction Usin g 3, 11, a n d d p p f
isolated yield of
isolated yield of
ligand
4-phenyltoluenea (%)
4-phenyltolueneb (%)
3
73
55
74
89
80
79
11
dppf
a
b
Using Pd(OAc)2 reagent. Using Pd2(dba)3 reagent.
the direction of the methoxy oxygen O(29). The Cu‚‚‚
O(29) distance is fairly short at 2.86 Å, although
comparable approaches of ethoxy oxygen atoms to
trigonal copper(I) centers have been observed previ-
ously.39 Both ferrocenyl units have significantly stag-
gered geometries [ca. 24° for Fe(1) and ca. 16° for Fe(2)],
and their P-C5 and O-C5 vectors are inclined by 93°
[Fe(1)] and 16° [Fe(2)], respectively. The closer to
eclipsed geometry observed at Fe(2) facilitates the
formation of an intramolecular C-H‚‚‚O hydrogen bond
between one of the ortho hydrogen atoms on the C(40)
phenyl ring and the methoxy oxygen atom O(29); the
C‚‚‚O and H‚‚‚O distances are 3.19 and 2.32 Å, and the
C-H‚‚‚O angle is 149°. There is a small π-π overlap
between the C(23) and C(40) phenyl rings, the centroid‚
‚‚centroid and mean-interplanar separations being 4.68
and 3.31 Å, respectively (the rings are inclined by ca.
8°). The PF6 anion and included DCM are both disor-
dered, and there are no intermolecular interactions of
note.
Ca ta lysis Stu d ies. We have recently reported the
application of 11 to the Suzuki reaction in conjunction
with Pd(0) precursors.18 Compound 3 was also investi-
gated with Pd(II) and Pd(0) reagents as a possible
system for the Suzuki reaction and its activity compared
to both 11 and 1,1′-bis(diphenylphosphino)ferrocene
(dppf) as a ligand of choice for this reaction. Following
the methodology of Buchwald et al.,40 either Pd(OAc)2
(1 mol %) or Pd2(dba)3‚C6H6 (1 mol %; 2 mol % Pd),
ligand (2 mol %), and 3 equiv of potassium fluoride were
stirred with the starting materials (1 mmol scale) in
THF (1 mL). The coupling reaction studied is shown in
Scheme 4. The reactions were carried out at 60 °C for 5
h. The crude product was purified by column chroma-
tography and the purity of the product checked by GC
analysis. The isolated yield of 4-phenyltoluene was used
as a measure of the effectiveness of each catalyst
system: the results are shown in Table 3.
Exp er im en ta l Section
Gen er a l P r oced u r es. All preparations were carried out
using standard Schlenk techniques.41 All solvents were dis-
tilled over standard drying agents under nitrogen directly
before use, and all reactions were carried out under an
atmosphere of nitrogen. Chromatographic separations were
carried out on silica gel (Kieselgel 60, 70-230 mesh). All NMR
spectra were recorded using a Delta upgrade on a J EOL EX270
MHz spectrometer operating at 270.1 MHz (1H) and 101.3 MHz
(31P{1H}). Chemical shifts (δ) are reported in ppm using CDCl3
(1H, 7.25 ppm), C6D6 (7.15 ppm), or CD2Cl2 (5.30 ppm) as the
reference, while 31P{1H} spectra were referenced to H3PO4.
Infrared spectra were recorded using NaCl solution cells (CH2-
Cl2) using a Perkin-Elmer 983 Fourier transform IR spectrom-
eter. Mass spectra were recorded using positive FAB methods,
on an Autospec Q mass spectrometer. Microanalyses were
carried out at SACS, University of North London.
Syn th eses: 1-(Br om o)-1′-(a cetoxy)fer r ocen e (1). A mix-
ture of 1,1′-dibromoferrocene (2.00 g, 5.82 mmol, 1 equiv),
acetic acid dried over molecular sieves (0.17 cm3, 2.91 mmol,
0.5 equiv), and copper(I) oxide (0.42 g, 2.91 mmol, 0.5 equiv)
was heated to reflux in dry acetonitrile (40 cm3) for 15 h under
nitrogen. After cooling, dichloromethane was added (75 cm3)
and the mixture filtered. The precipitate was washed with
dichloromethane (30 cm3). The green filtrate and washings
were combined and extracted with water (50 cm3), and the
layers were separated. The orange organic layer was dried
(MgSO4) and the solvent removed in vacuo to yield an orange
oily solid. The crude mixture was purified by column chroma-
tography (silica, toluene), yielding 1 as an orange oil (0.24 g,
With Pd(OAc)2, dppf was found to be a more effective
catalyst than 11. This is thought to be due to the fact
that dppf is more effective in reducing Pd(II) to Pd(0),
a necessary step before the cross-coupling reaction can
take place. Compound 3, however, was found to have
an activity similar to that of dppf. With Pd2(dba)3, under
(39) Ogo, S.; Suzuki, T.; Isobe, K. Inorg. Chem. 1995, 34, 1304.
(40) Wolfe, J . P.; Singer, R. A.; Yang, B. H.; Buchwald, S. L. J . Am.
Chem. Soc. 1999, 121, 9550.
(41) Errington, R. J . Advanced Practical Inorganic and Metalorganic
Chemistry; Blackie: London, 1997.

2750 Organometallics, Vol. 23, No. 11, 2004
Atkinson et al.
0.74 mmol, 13%). Anal. Calcd for C12H11BrFeO2: C 44.63, H
3.43. Found: C 44.45, H 3.59. IR (CH2Cl2) cm-1: 1755 (s, Cd
O) 1270 (vs, C-O). 1H NMR δ (CDCl3) ppm: 2.18 (s, 3H, CH3),
3.99 (br t, 2H, C5H4OAc), 4.13 (br t, 2H, C5H4Br), 4.44 (br t,
2H, C5H4OAc), 4.46 (br t, 2H, C5H4Br). m/z: 324, 322 (M+),
282, 280 (M+ - CH3CO), 244 (M+ - Br).
1-(Br om o)-1′-(m eth oxy)fer r ocen e (2). F r om 1. To a
stirred solution of 1 (0.24 g, 0.74 mmol, 1 equiv), 15-crown-5
(0.05 cm3, 0.24 mmol, 0.33 equiv), and iodomethane (0.16 cm3,
2.5 mmol, 3.4 equiv) in dry deoxygenated THF (15 cm3) under
nitrogen was added sodium hydride (60% in mineral oil, 0.19
g, 4.0 mmol, 5.4 equiv). The reaction mixture was stirred at
room temperature for 15 h. The reaction mixture was then
filtered and the solvent removed in vacuo to yield an orange
oil. The crude product was purified by column chromatography
(silica, toluene), yielding 2 as an orange oil (0.17 g, 0.57 mmol,
77% from 1, 10% from 1,1′-dibromoferrocene). Anal. Calcd for
Schlenk tube, in a glovebox, containing 3 (0.05 g, 0.125 mmol,
1 equiv). Dry, deoxygenated CH2Cl2 (20 cm3) was added,
causing the solution to turn green. The Schlenk tube was
suspended in an oil bath and the reaction mixture stirred for
24 h at 35 °C. The solvent was removed in vacuo, and the green
precipitate was washed with dry hexane (10 cm3), yielding 4
as a green, air-sensitive powder (0.03 g, 0.05 mmol, 43%). Anal.
Calcd for C23H21Br2FeNiOP: C 44.65, H 3.42. Found: C 44.63,
H 3.56. 31P NMR δ (CDCl3) ppm: 29.8. m/z: 400 (M+ - NiBr2).
Dich lor o[1-(d ip h en ylp h osp h in o-KP )-1′-(m eth oxy-KO)-
fer r ocen e]p a lla d iu m (II) (5). 3 (0.10 g, 0.25 mmol, 1 equiv)
was dissolved in dry toluene (7 cm3) and added via cannula to
dichloro(1,5-cyclooctadiene)palladium(II) (0.07 g, 0.23 mmol,
0.9 equiv) dissolved in dry CH2Cl2 (20 cm3). The solution was
stirred for 20 h under nitrogen. The solution was concentrated
by half in vacuo, dry hexane (10 cm3) added, and the mixture
filtered. The brown residue was washed with dry hexane (10
cm3), yielding 5 as a brown powder (0.10 g, 0.18 mmol, 70%).
Anal. Calcd for C23H21Cl2FeOPPd: C 47.83, H 3.66. Found: C
47.64, H 3.49. 1H NMR δ (CDCl3) ppm: 3.71 (s, 3H, OCH3),
4.53 (m, 4H, C5H4) 4.60 (m, 4H, C5H4), 7.45 (m, 10H, PC6H5).
C
11H11BrFeO: C 44.79, H 3.76. Found: C 44.89, H 3.58. IR
1
(CH2Cl2) cm-1: 1272 (s, C-O). H NMR δ (CDCl3) ppm: 3.90
(s, 3H, CH3) 3.99 (t, 2H, C5H4), 4.07 (t, 2H, C5H4), 4.11 (t, 2H,
C5H4), 4.40 (t, 2H, C5H4). m/z: 296, 294 (M+), 216 (M+ - Br).
Acc. mass calcd for
293.934616.
C
11H11BrFeO: 293.934265, found
31P{1H} NMR δ (CDCl3) ppm: 31.9. m/z: 578 (M+), 543 (M+
-
Cl), 506 (M+ - 2Cl).
2. F r om 1,1′-Dib r om ofer r ocen e. 1,1′-Dibromoferrocene
(0.50 g, 1.45 mmol, 1 equiv) was dissolved in dry THF (40 cm3)
and cooled to -25 °C. To this solution was added n-butyl-
lithium (1.6 M in hexanes, 0.86 cm3, 1.38 mmol, 0.95 equiv)
and the solution stirred at -25 °C for 30 min. The solution
was cooled to -78 °C, and bis(trimethylsilyl) peroxide (0.24
cm3, 2.18 mmol, 1.5 equiv) was added dropwise slowly. The
solution was stirred at -78 °C for 1 h and then allowed to
warm to room temperature. The THF was removed in vacuo
and the residue redissolved in nitrogen-saturated acetone (35
cm3). K2CO3 (1.24 g, 9.00 mmol, 6.2 equiv) was added and Me2-
SO4 added via syringe (1.03 cm3, 11.0 mmol, 7.5 equiv). The
mixture was refluxed for 20 h, cooled, and filtered, and the
solvent was removed in vacuo to yield an orange oil. The crude
product was purified by column chromatography (silica, toluene/
hexane, 1:1), and 2 was obtained as an orange oil (0.241 g,
0.82 mmol, 56% from 1,1′-dibromoferrocene).
1-(Dip h en ylp h osp h in o)-1′-(m eth oxy)fer r ocen e (3). 2
(0.80 g, 2.71 mmol, 1 equiv) was dissolved in dry THF (25 cm3)
and cooled to -78 °C. To this solution was added n-butyl-
lithium (1.6 M in hexanes, 1.69 mL, 2.71 mmol, 1 equiv) and
the solution stirred at -78 °C for 10 min. Chlorodiphenylphos-
phine (0.60 mL, 3.25 mmol, 1.2 equiv) was added and the
mixture allowed to warm to room temperature. The solution
was stirred at room temperature for 20 h, the solvent was
removed in vacuo, and the residue was redissolved in CH2Cl2
(50 cm3). Water was added (50 cm3) and the layers were
separated. The aqueous layer was washed with CH2Cl2 (25
cm3), the organic layers were combined and dried (MgSO4),
and the solvent was removed in vacuo to yield an orange oily
solid. The crude mixture was purified by column chromatog-
raphy (silica, hexane/CH2Cl2, 2:1) to give an orange oil. Pure
3 was obtained as an orange solid after recrystallization from
pentane (0.43 g, 1.09 mmol, 40%). Crystals suitable for X-ray
diffraction were grown by slow evaporation from pentane
Bis[1-(d ip h en ylp h osp h in o-KP )-1′-(m eth oxy)fer r ocen e]-
d ich lor op la tin u m (II) (6). 3 (0.10 g, 0.25 mmol, 2.1 equiv)
was dissolved in dry toluene (3 cm3) and added via cannula to
a solution of bis(benzonitrile)platinum dichloride (0.06 g, 0.12
mmol, 1 equiv) in dry DCM (7 cm3). The solution was stirred
for 20 h under nitrogen at room temperature, after which time
an orange precipitate was visible. The solution was concen-
trated in vacuo, dry hexane (10 cm3) was added, resulting in
complete precipitation of the product, and the mixture was
filtered. The product was washed with dry hexane (10 cm3)
and filtered to yield 6 as an orange powder (0.10 g, 0.10 mmol,
80%). Crystals suitable for X-ray diffraction were grown by
slow evaporation of hexane from a DCM solution of the
complex. Anal. Calcd for C46H42Cl2Fe2O2P2Pt: C 51.81, H 3.97.
Found: C 51.53, H 3.77. 1H NMR δ (CDCl3) ppm: 3.57 (s, 3H,
OCH3), 4.28 (m, 4H, C5H4) 4.45 (t, 2H, C5H4), 4.59 (t, 2H, C5H4),
7.38 (m, 10H, PC6H5). 31P{1H} NMR δ (CDCl3) ppm: 11.0 (s,
1J Pt-P 2620 Hz). 13C{1H} NMR δ (CD2Cl2) ppm: 56.89 (s, C5H4),
57.78 (s, OCH3), 65.29 (s, C5H4), 71.10 (s, C5H4), 72.65 (s, C5H4),
3
75.51 (br d, C5H4), 76.61 (s, C5H4), 127.83 (t, m-C6H5, J C-P
1
19.6 Hz), 130.55, (s, p-C6H5), 131.16 (t, ipso-C6H5, J C-P 117.2
2
Hz), 134.58 (t, o-C6H5, J C-P 22.4 Hz). m/z: 1066 (M+), 1030
(M+ - Cl), 995 (M+ - 2Cl).
Bis[1-(d ip h en ylp h osp h in o-KP )-1′-(m eth oxy)fer r ocen e]-
ca r bon ylch lor or h od iu m (I) (9). 3 (0.08 g, 0.20 mmol, 2.1
equiv) was dissolved in dry Et2O (10 cm3) and added via
cannula to a solution of tetracarbonyldichlorodirhodium(I)
(0.04 g, 0.10 mmol, 1 equiv) in dry methanol (20 cm3). The
solution was stirred at room temperature for 2 h, after which
time an orange precipitate was visible. The solution was
concentrated in vacuo and the mixture filtered. The residue
was washed with Et2O (10 cm3) and methanol (10 cm3),
yielding 9 as an orange powder (0.05 g, 0.05 mmol, 47%). Anal.
Calcd for C47H42ClFe2O3P2Rh: C 58.39, H 4.38. Found:
C
58.56, H 4.49. 1H NMR δ (CD2Cl2) ppm: 3.52 (s, 3H, CH3),
4.12 (t, 2H, C5H4), 4.21 (t, 2H, C5H4), 4.48 (m, 4H, C5H4), 7.39
(m, 6H, PC6H5), 7.66 (m, 4H, PC6H5). 31P{1H} NMR δ (CD2-
solution. Anal. Calcd for
C23H21FeOP: C 69.02, H 5.29.
Found: C 69.07, H 5.26. 1H NMR δ (CDCl3) ppm: 3.52 (s, 3H,
CH3) 3.70 (t, 2H, C5H4), 3.99 (t, 2H, C5H4), 4.12 (t, 2H, C5H4),
4.40 (t, 2H, C5H4), 7.28 (m, 10H, PC6H5). 31P{1H} NMR δ
(CDCl3) ppm: -16.4. 13C{1H} NMR δ (CDCl3) ppm: 55.88 (s,
C5H4), 57.37 (s, OCH3), 63.17 (s, C5H4), 71.35 (s, C5H4), 73.16
1
Cl2) ppm: 22.74 (d, J Rh-P 126 Hz). 13C{1H} NMR δ (C6D6)
ppm: 57.02 (s, C5H4), 57.10 (s, OCH3), 65.56 (s, C5H4), 72.32
(s, C5H4), 74.69 (s, C5H4), 74.95 (s, C5H4), 75.42 (s, C5H4), 128.91
(br t, m-C6H5), 129.89, (s, p-C6H5), 134.50 (t, o-C6H5, 2J C-P 24.8
Hz), 128.01 (br t, ipso-C6H5), 135.96 (t, CO, 2J C-P 91.6 Hz). IR
(CH2Cl2, cm-1): ν(CO) 1968. m/z: 966 (M+), 931 (M+ - Cl),
903 (M+ - CO - Cl).
Bis[1-(d ip h en ylp h osp h in o-KP )-1′-(m eth oxy)fer r ocen e]-
a ceton itr ilecop p er (I) Hexa flu or op h osp h a te (10). 3 (0.08
g, 0.20 mmol, 2.1 equiv) was dissolved in dry CH2Cl2 (5 cm3)
and added via cannula to a solution of tetrakis(acetonitrile)-
1
(d, ipso-C5H4, J C-P 59.48 Hz), 75.9 (s, C5H4), 76.1 (s, C5H4),
128.24 (d, ipso-C6H5, 1J C-P 185.6 Hz), 128.09 (d, m-C6H5, 3J C-P
2
26 Hz), 128.40, (s, p-C6H5), 133.45 (d, o-C6H5, J C-P 76 Hz).
m/z: 400 (M+).
Dibr om o[1-(d ip h en ylp h osp h in o-KP )-1′-(m eth oxy-KO)-
fer r ocen e]n ick el(II) (4). Bis(1,2-dimethoxyethane)dibromo-
nickel(II) (0.04 g, 0.11 mmol, 0.9 equiv) was added to a dry

Unsymmetrical P/ O Ferrocenediyl Ligand
Organometallics, Vol. 23, No. 11, 2004 2751
copper(I) hexafluorophosphate (0.04 g, 0.10 mmol, 1 equiv) in
CH2Cl2 (10 cm3). The solution was stirred at room temperature
for 2 h. The solvent was removed in vacuo and the precipitate
washed with hexane (2 × 10 cm3) and dried in vacuo, yielding
10 as an orange powder (0.05 g, 0.05 mmol, 56%). Crystals
suitable for X-ray analysis were grown by layering a DCM
) 18.440(2) Å, â ) 93.771(5)°, V ) 1990.5(4) Å3, Z ) 2 [Ci
symmetry], Dc ) 1.779 g cm-3, µ(Mo KR) ) 4.479 mm-1, T )
203 K, yellow blocks; 3510 independent measured reflections,
F2 refinement, R1 ) 0.037, wR2 ) 0.070, 2618 independent
observed absorption-corrected reflections [|Fo| > 4σ(|Fo|), 2θmax
) 50°], 226 parameters.
Crystal data for 10: [C48H45CuFe2NO2P2](PF6)‚CH2Cl2, M
) 1134.93, triclinic, P1h (no. 2), a ) 12.7069(6) Å, b ) 13.2745-
(7) Å, c ) 14.9398(14) Å, R ) 78.179(4)°, â ) 83.475(6)°, γ )
84.346(4)°, V ) 2443.2(3) Å3, Z ) 2, Dc ) 1.543 g cm-3, µ(Mo
KR) ) 1.288 mm-1, T ) 293 K, yellow-orange prisms; 8603
independent measured reflections, F2 refinement, R1 ) 0.057,
wR2 ) 0.126, 5591 independent observed absorption-corrected
reflections [|Fo| > 4σ(|Fo|), 2θmax ) 50°], 623 parameters. CCDC
236260-236262.
solution of the complex with hexane. Anal. Calcd for C48H45
-
CuF6Fe2NO2P3: C 54.90, H 4.32, N 1.33. Found: C 55.08, H
4.47, N 1.15. 1H NMR δ (CDCl3) ppm: 2.10 (s, 3H, CH3CN)
3.45 (s, 3H, OCH3), 3.60 (m, 2H, C5H4), 3.95 (m, 2H, C5H4),
4.10 (m, 2H, C5H4), 4.51 (m, 2H, C5H4) 7.34 (m, 10H, PC6H5).
- 1
31P{1H} NMR δ (CDCl3) ppm: -143.64 (septet, PF6
J
712
P-F
Hz) -6.44 (s, PPh2). 13C{1H} NMR δ (CD2Cl2) ppm: 30.97 (s,
CH3CN), 56.84 (s, C5H4), 58.17 (s, OCH3), 64.26 (s, C5H4), 72.82
(s, C5H4), 72.96 (s, C5H4), 73.34 (br d, C5H4), 73.89 (s, C5H4),
121.54 (s, CH3CN), 129.18 (br s, ipso-C6H5), 129.28 (br s,
m-C6H5), 131.11 (br s, p-C6H5), 133.43 (br s, o-C6H5). m/z: 863
(M+ - MeCN), 463 (M+ - MeCN - L), 400 (L+).
Ack n ow led gm en t. We acknowledge financial sup-
port from the Department of Chemistry, Imperial Col-
lege, London, and J ohnson Matthey plc is thanked for
the loan of the palladium, platinum, and rhodium salts.
Crystal data for 3: C23H21OPFe, M ) 400.22, triclinic, P1h
(no. 2), a ) 8.025(2) Å, b ) 10.796(2) Å, c ) 11.814(3) Å, R )
100.77(2)°, â ) 96.97(2)°, γ ) 101.507(12)°, V ) 971.8(4) Å3, Z
) 2, Dc ) 1.368 g cm-3, µ(Mo KR) ) 0.866 mm-1, T ) 293 K,
yellow plates; 3409 independent measured reflections, F2
refinement, R1 ) 0.039, wR2 ) 0.091, 2745 independent
observed absorption-corrected reflections [|Fo| > 4σ(|Fo|), 2θmax
) 50°], 211 parameters.
Su p p or tin g In for m a tion Ava ila ble: Details on the X-ray
crystal structures of 3, 6, and 10, including ORTEP diagrams,
tables of crystal data and structure refinement, atomic coor-
dinates, bond lengths and angles, and isotropic and anisotropic
displacement parameters. This material is available free of
charge via the Internet at http://pubs.acs.org.
Crystal data for 6:
monoclinic, P21/c (no. 14), a ) 9.4390(8) Å, b ) 11.460(2) Å, c
C46H42O2P2Cl2Fe2Pt, M ) 1066.43,
OM0343768