Structural Characterization of Heterodimetallic Zr/Pd and Zr/Rh Catalyst Precursors Containing the C5H4PPh2 Ligand

Article abstract of DOI:10.1021/om990685f

(Cp-PPh₂)₂ZrCl₂ (5) reacts with (PhCN)₂PdCl₂ to yield the early-late heterodimetallic complex [(Cp-PPh₂)₂ZrCl₂/PdCl₂], 7, which was characterized by an X-ray crystal structure analysis. The phosphine-substituted bent metallocene moiety in 7 serves as a conformationally flexible chelate phosphine ligand (angle P-Pd-P: 96.46(3)°). Complex 7 is an active catalyst for the cross-coupling of sec-butylmagnesium bromide with bromobenzene, leading to excellent regioselectivity and moderate reactivity. Complex 5 reacts with dicarbonylrhodium chloride dimer (0.5 equiv) to yield the triply bridged complex 12, [ClZr(μ-Cp-PPh₂)₂-(μ-Cl)Rh(CO)Cl], which was also characterized by X-ray diffraction (the angle P-Rh-P is 158° at the distorted square-pyramidal pentacoordinated rhodium center). (Cp-PPh₂)₂Zr-(CH₃)₂ (13) reacts with [H(CO)Rh(PPh₃)₃] (14) with loss of two PPh₃ ligands and instantaneous liberation of methane to form complex 15, [CH₃Zr(μ-Cp-PPh₂)₂Rh(CO)PPh ₃](Zr-Rh), which probably contains a metal-metal bond between the early and late transition metal. Complex 15 is a very active 1-hexene hydroformylation catalyst (TOF > 600, n/iso ≈ 3 at 80°C).

Full text of DOI:10.1021/om990685f

Organometallics 2000, 19, 1255-1261
1255
Str u ctu r a l Ch a r a cter iza tion of Heter od im eta llic Zr /P d
a n d Zr /Rh Ca ta lyst P r ecu r sor s Con ta in in g th e C5H4P P h 2
Liga n d
Boris E. Bosch, Ingo Bru¨mmer, Klaus Kunz, Gerhard Erker,*
Roland Fro¨hlich,† and Sirpa Kotila†
Organisch-Chemisches Institut der Universita¨t Mu¨nster, Corrensstrasse 40,
D-48149 Mu¨nster, Germany
Received August 26, 1999
(Cp-PPh2)2ZrCl2 (5) reacts with (PhCN)2PdCl2 to yield the early-late heterodimetallic
complex [(Cp-PPh2)2ZrCl2/PdCl2], 7, which was characterized by an X-ray crystal structure
analysis. The phosphine-substituted bent metallocene moiety in 7 serves as a conforma-
tionally flexible chelate phosphine ligand (angle P-Pd-P: 96.46(3)°). Complex 7 is an active
catalyst for the cross-coupling of sec-butylmagnesium bromide with bromobenzene, leading
to excellent regioselectivity and moderate reactivity. Complex 5 reacts with dicarbonyl-
rhodium chloride dimer (0.5 equiv) to yield the triply bridged complex 12, [ClZr(µ-Cp-PPh2)2-
(µ-Cl)Rh(CO)Cl], which was also characterized by X-ray diffraction (the angle P-Rh-P is
158° at the distorted square-pyramidal pentacoordinated rhodium center). (Cp-PPh2)2Zr-
(CH3)2 (13) reacts with [H(CO)Rh(PPh3)3] (14) with loss of two PPh3 ligands and instanta-
neous liberation of methane to form complex 15, [CH3Zr(µ-Cp-PPh2)2Rh(CO)PPh3](Zr-Rh),
which probably contains a metal-metal bond between the early and late transition metal.
Complex 15 is a very active 1-hexene hydroformylation catalyst (TOF > 600, n/iso ≈ 3 at
80 °C).
In tr od u ction
ized by X-ray diffraction, and only a few of these and
the related Cp2M[-(CR2)nPR2]2-type systems 3 were
employed in the development of catalytic reactions.8,9
We have now prepared a few novel (Cp-PPh2)ZrX2/
palladium and rhodium complexes, characterized two
Phosphine ligands are extensively used in homoge-
neous catalysis, and especially chelate phosphines are
of enormous importance.1 Phosphines that are attached
at organometallic frameworks have been very useful for
a number of catalytic applications, with 1,1′-bis(diphen-
ylphosphino)ferrocene and its derivatives being very
typical examples.2 One might envisage that the analo-
gous phosphine derivatives of the group 4 bent metal-
locenes may become of a similar usefulness as chelate
ligands in catalysis,3 especially since their central MX2
moiety may open additional possibilities for catalyst
activation, offering ways of coordinative or electronic
support of the catalytic process and the action of the
active catalyst center.
The organometallic chemistry of the Cp-PPh2 ligand
at group 4 metal complexes is developed to a significant
extent. There are a variety of examples of the complex
type 1 and 2 (see Chart 1)4,5 and related systems6,7
known, although surprisingly few examples of the
heterodimetallic metallocene systems were character-
(4) Rausch, M. D.; Edwards, B. H.; Rogers, R. D.; Atwood, J . L. J .
Am. Chem. Soc. 1983, 105, 3882. Tikkanen, W.; Fujita, Y.; Petersen,
J . L. Organometallics 1986, 5, 888. Anderson, G. K.; Lin, M. Organo-
metallics 1988, 7, 2285. Schenk, W. A.; Labude, C. Chem. Ber. 1989,
122, 1489. Moros, D.; Tikkanen, W. J . Organomet. Chem. 1989, 371,
15. Szymoniak, J .; Kubicki, M. M.; Besanc¸on, J .; Moise, C. Inorg. Chim.
Acta 1991, 180, 153. Schenk, W. A.; Neuland-Labude, C. Z. Naturfor-
sch. 1991, 46b, 573. Baudry, D.; Dormond, A.; Visseaux, M.; Monnot,
C.; Chardot, H.; Lin, Y.; Bakhmutov, V. New J . Chem. 1995, 19, 921.
Delgado, E.; Fornies, J .; Hernandez, E.; Lalinde, E.; Mansilla, N.;
Moreno, M. T. J . Organomet. Chem. 1995, 494, 261. Bakhmutov, V.
I.; Visseaux, M.; Baudry, D.; Dormond, A.; Richard, P. Inorg. Chem.
1996, 35, 7316. Delgado, E.; Herna´ndez, E.; Mansilla, N.; Moreno, M.
T.; Sabat, M. J . Chem. Soc., Dalton Trans. 1999, 533.
(5) Casey, C. P.; Nief, F. Organometallics 1985, 4, 1281. Bullock, R.
M.; Casey, C. P. Acc. Chem. Res. 1987, 20, 167.
(6) For related systems see for example: Kool, L. B.; Ogasa, M.;
Rausch, M. D.; Rogers, R. D. Organometallics 1989, 8, 1785. Rausch,
M. D.; Ogasa, M.; Ayers, M. A.; Rogers, R. D.; Rollins, A. N.
Organometallics 1991, 10, 2481.
(7) (a) Schore, N. E. J . Am. Chem. Soc. 1979, 101, 7410. Tueting,
D. R.; Iyer, S. R.; Schore, N. E. J . Organomet. Chem. 1987, 320, 349.
(b) Leblanc, C.; Moise, C.; Maisonnat, A.; Poilblanc, R.; Charrier, C.;
Mathey, F. J . Organomet. Chem. 1982, 231, C43. (c) Bosch, B. E.;
Erker, G.; Fro¨hlich, R. Inorg. Chim. Acta 1998, 270, 446.
(8) Gelmini, L.; Stephan, D. W. Inorg. Chem. 1986, 25, 1222;
Organometallics 1988, 7, 849. Baker, R. T.; Fultz, W. C.; Marder, T.
B.; Williams, I. D. Organometallics 1990, 9, 2357. (b) Choukroun, R.;
Gervais, D. J . Chem. Soc., Chem. Commun. 1982, 1300. Senocq, F.;
Randrianalimanana, C.; Thorez, A.; Kalck, P.; Choukroun, R.; Gervais,
D. J . Chem. Soc., Chem. Commun. 1984, 1376. Choukroun, R.; Gervais,
D. J . Organomet. Chem. 1984, 266, C37. Senocq, F.; Basso-Bert, M.;
Choukroun, R.; Gervais, D. J . Organomet. Chem. 1985, 297, 155.
Choukroun, R.; Dahan, F.; Gervais, D.; Rifai, C. Organometallics 1990,
9, 1982.
* Corresponding author. Fax: +49 251 83 36503. E-mail: erker@
uni-muenster.de.
† X-ray crystal structure analyses.
(1) Parschall, G. W.; Ittel, S. D. Homogeneous Catalysis, 2nd ed.;
Wiley: New York, 1992. Masters, C. Homogeneous Transition Metal
Catalysis-A Gentle Art; Chapman and Hall: London, 1981. Cornils,
B., Herrmann, W. A., Eds. Applied Homogeneous Catalysis with
Organometallic Compounds, A Comprehensive Handbook in Two
Volumes; VCH: Weinheim, 1996.
(2) Togni, A., Hayashi, T., Eds. Ferrocenes; Homogeneous Catalysis,
Organic Synthesis, Materials Science; VCH: Weinheim, 1995.
(3) Casey, C. P.; Bullock, R. M.; Fultz, W. C.; Rheingold, A. L.
Organometallics 1982, 1, 1591.
(9) Review: Stephan, D. W. Coord. Chem. Rev. 1989, 95, 41.
10.1021/om990685f CCC: $19.00 © 2000 American Chemical Society
Publication on Web 03/09/2000

1256 Organometallics, Vol. 19, No. 7, 2000
Bosch et al.
Ch a r t 1. Selection of P r eviou sly Rep or ted Typ es
of P h osp h in e-Con ta in in g Ea r ly(gr ou p 4)-La te
Heter od im eta llic Com p lexes
F igu r e 1. Molecular structure of the Zr/Pd complex 7
(with unsystematical atom-numbering scheme). Selected
bond lengths (Å) and angles (deg) (additional values are
given in the text): Zr-Cl11 2.416(1), Zr-Cl12 2.419(1),
Zr-CCp1 2.514(4), Zr-CCp2 2.515(4), Pd-Cl21 2.330(1),
Pd-Cl22 2.346(1), Pd-P1 2.279(1), Pd-P2 2.278(1),
P1-C11 1.811(4), P1-C111 1.814(3), P1-C121 1.829(4),
P2-C21 1.804(3), P2-C211 1.826(4), P2-C221 1.825(3);
Cl11-Zr-Cl12 96.25(4), Zr-C11-P1 131.9(2), Zr-C21-
P2 128.9(2), C11-P1-Pd 115.3(1), C111-P1-Pd 112.4(1),
C121-P1-Pd 115.5(1), C11-P1-C111 110.1(2), C11-P1-
C121 101.3(2), C111-P1-C121 100.8(2), C21-P2-Pd
122.0(1), C211-P2-Pd 113.1(1), C221-P2-Pd 112.1(1),
C21-P2-C211 101.4(2), C21-P2-C221 101.4(2), C211-
P2-C221 104.9(2), Cl21-Pd-Cl22 88.12(4), P1-Pd-P2
96.46(3), Cl21-Pd-P1 89.42(3), Cl21-Pd-P2 174.11(3),
Cl22-Pd-P1 175.21(4), Cl22-Pd-P2 86.03(3).
examples by X-ray crystal structure analyses, and found
that such early-late heterodimetallic systems may have
quite some potential in homogeneous catalysis.
Resu lts a n d Discu ssion
Syn th esis, Str u ctu r e, a n d Ca ta lytic F ea tu r es of
a Zir con iu m /P a lla d iu m System . Bis(diphenylphos-
phinocyclopentadienyl)zirconium dichloride (5) was pre-
pared by treatment of ZrCl4(thf)2 with (Cp-PPh2)Li,
analogously as described by W. Tikkanen et al.10 The
organometallic chelate phosphine ligand 5 was obtained
as a colorless solid in 80% yield. It was then treated
with bis(benzonitrile)palladium dichloride (6) in dichlo-
romethane (-78 °C to room temperature). Two equiva-
lents of benzonitrile were cleaved off, and the adduct
κ2P,P′-[(Cp-PPh2)2ZrCl2]PdCl2 (7) was isolated as a pale
yellow solid (85% yield). It shows a 31P NMR resonance
at δ 29.0 ppm (5: δ -17.0 ppm) and two C5H4 1H NMR
multiplets at δ 6.91 and 6.34 ppm [corresponding 13C
NMR methine resonances of the Ph2P-substituted Cp-
Ch a r t 2. Str u ctu r e of th e (d p p f)P d Cl2 Ca ta lyst
P r ecu r sor
The coordination geometry at palladium is distorted
square-planar (see Figure 1). The chelate phosphine
ligand binds to adjacent cis-positions at Pd (d(P(1)-Pd)
) 2.279(1) Å, d(P(2)-Pd) ) 2.278(1) Å, d(Cl(21)-Pd) )
2.330(1) Å, d(Cl(22)-Pd) ) 2.346(1) Å). These bond
distances are very similar to those found in (dppf)PdCl2
(10) (see Chart 2; d(P-Pd) ) 2.301(1), 2.283(1) Å;
d(Cl-Pd) ) 2.347(1), 2.348(1) Å13). The “bite angle” of
a bent metallocene is in principle variable; it will ad-
just favorably to the stereoelectronic needs of the
coordinated late transition metal. In 7 this leads to a
P(1)-Pd-P(2) angle of 96.46(3)°, which is noticeably
smaller than the P-Pd-P bite angle in 10 of 99.07(5)°.13
The remaining bond angles around palladium in 7 are
89.42(3)° (P(1)-Pd-Cl(21)), 88.12(4)° (Cl(21)-Pd-Cl-
(22)), and 86.03(3)° (P(2)-Pd-Cl(22)). The C(Cp)-P-
Pd coordination angles amount to 115.3(1)° (at P(1)) and
122.0(1)° (at P(2)). The remaining bond angles at the
tetravalent phosphorus atoms are markedly smaller as
expected (see Figure 1).
ligand at δ 127.5 (1J PC ) 6.9 Hz) and δ 121.4 (1J PC
8.6 Hz)].
)
Diffusion of pentane into a dichloromethane solution
of 7 furnished single crystals for the X-ray crystal
structure analysis. In the structure of 7 the zircon-
ium and palladium atoms are well separated (Zr‚‚‚Pd
4.723(1) Å).7c,11 They are connected by means of the
bridging Cp-PPh2 ligands, the Cp-parts of which are
coordinated to zirconium and the phosphorus atoms to
palladium. The bent metallocene moiety of 7 shows
unexceptional bonding parameters. The Cp(centroid)-
Zr-Cp(centroid) angle is 130.3°, the Cl(11)-Zr-Cl(12)
angle amounts to 96.25(4)° (d(Zr-Cl(11)) ) 2.416(1) Å;
d(Zr-Cl(12)) ) 2.419(1) Å). These values are in the
typical range of Cp2ZrCl2 complexes.12 The substituted
zirconocene unit exhibits a staggered metallocene con-
formation. Both Ph2P-substituents are oriented toward
the backside of the bent metallocene wedge. They are
located there in close conformational proximity at
adjacent staggered positions.
(13) (a) Hayashi, T.; Konishi, M.; Kumada, M. Tetrahedron Lett.
1979, 21, 1871. (b) See also: Butler, I. R.; Cullen, W. R.; Kim, T.-J .;
Rettig, S. J .; Trotter, J . Organometallics 1985, 4, 972. (c) Reviews:
Hartwig, J . F. Angew. Chem. 1998, 110, 2154; Angew. Chem., Int. Ed.
1998, 37, 2046. Diederich, F.; Stang, P. J . Metal-catalyzed Cross-
coupling Reactions; Wiley-VCH: Weinheim, 1998.
(10) Tikkanen, W.; Ziller, J . W. Organometallics 1991, 10, 2266.
(11) See for a comparison: Bosch, B. E.; Erker, G.; Fro¨hlich, R.;
Meyer, O. Organometallics 1997, 16, 5449.
(12) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson,
D. G.; Taylor, R. J . Chem. Soc., Dalton Trans. 1989, S1.

Zr/ Pd and Zr/ Rh Catalyst Precursors
Organometallics, Vol. 19, No. 7, 2000 1257
Sch em e 1
Sch em e 2
A similar overall trend was observed in the cross-
coupling reaction between sec-butylmagnesium bromide
and p-bromoanisol, catalyzed by 7, 10, and PdCl2-
(PPh3)2.
Zir con iu m /R h od iu m Com p lexes. Treatment of
(Cp-PPh2)2ZrCl2 (5) with 0.5 molar equiv of [(CO)2RhCl]2
(11) gave the 1:1 adduct 12, which was isolated in close
to 90% yield. The product shows a single 31P NMR
1
resonance at δ 8.1 ppm with a J Rh-P coupling constant
Ta ble 1. P d -Ca ta lyzed Cr oss-Cou p lin g Rea ction s
betw een sec-Bu tylm a gn esiu m Br om id e a n d
Br om oben zen e or p-Br om oa n isola
of 93 Hz. Together with the observation of a set of four
C5H4-methine 1H NMR signals at δ 6.60, 6.45, 6.05, and
5.84 (corresponding 13C NMR resonances at δ 121.1,
116.4, 116.1, 105.3 ppm) this points to a distorted
pentacoordinated geometry at rhodium.15 Complex 12
exhibits an IR ν˜(CO) band at 1990 cm-1 (in KBr) [RhCl-
(CO)(PR3)2: ν˜ ) 1969 cm-1 (PEtPh2); 1974 cm-1 (PMe-
Ph2)16]. Single crystals of 12 were obtained from tet-
rahydrofuran.The yellow needles contained four molecules
of disordered solvent THF in the unit cell. In the solid
state, the molecules of 12 are Cs-symmetric, with the
symmetry plane lying in the zirconocene σ-ligand plane.
The two metal centers are connected again by two κP,η5-
C5H4-PPh2 ligands, and in addition they are bridged
by a µ-chloride ligand. The Cp(centroid)-Zr-Cp(cen-
troid) angle at zirconium is 131.6°, which is in the
typical group 4 bent metallocene range. However, the
Cl(1)-Zr-Cl(2) angle is at 80.3(1)°, much smaller than
usually observed (e.g., 7: ∼96°). Also the Zr-Cl(1)
(2.556(3) Å) and Zr-Cl(2) (2.504(4) Å) bond lengths are
increased from the typical zirconocene dichloride val-
ues.12,17 Both these features may indicate some zirconium/
rhodium interaction; the Zr‚‚‚Rh separation in 12 is
2.997(2) Å, which is just outside the sum of the covalent
radii.18
cat.
temp
rt
rxn time
% 8a
8bb
7
1 h
4.5 h
16 days
26 h
0.5 h
2 h
5.25 h
24 h
48 h
24 h
8 h
11
33
53
40
35
78
98
5
<1
<1
<1
,1
<1
<1
<1
6
7
10
-30 °C
rt
c
PdCl2(PPh3)2
PdCl2(dppe)c
PdCl2(dppp)c
PdCl2(dppp)c
rt
40 °C
r.t.
r.t.
43
51
19
25
cat.
temp
rxn time
% 9a
9bd
7
10
rt
rt
rt
19 h
19 h
18 h
16
75
3
<1e
1
2
PdCl2(PPh3)2
a
Reactions in ether employing 5 mol % of the respective
catalyst. Structures of the products are depicted in Scheme 1.
b
Total conversion determined by GPC with internal standard
n-dodecane, rest to 100% is starting material. c From ref 14a.
Products derived from p-bromoanisol. e Contains traces of anisol.
d
Complex 7 catalyzes the cross-coupling between sec-
butylmagnesium bromide and bromobenzene to give sec-
butylbenzene very selectively with only trace admix-
tures of the isomeric n-butylbenzene coupling product.
In view of the regioselective outcome the catalyst 7
(employed in 5 mol % concentration in these experi-
ments) equals the conventionally used (dppf)PdCl2
catalyst 10, but is considerably less active.13a,14 Typi-
cally, the catalysis by 7 gives ca. 33% of 8a (with only
a <1% trace of 8b, see Scheme 1 and Table 1) after ca.
4.5 h at ambient temperature; in a comparison, complex
10 has catalytically transformed this mixture of the
starting materials to an extent of 95% after 2 h at
ambient temperature (8a :8b > 80:1). In turn, complex
7 catalyzes the sec-butylmagnesium bromide plus bro-
mobenzene cross-coupling reaction considerably better
than the conventional catalysts PdCl2(PPh3)2, PdCl2-
(dppe), PdCl2(dppp), or PdCl2(dppb) (i.e., with the che-
late ligands bis(diphenylphosphino)ethane, -propane, or
-butane), with regard to both activity and selectivity.14a
The rhodium coordination is distorted square-pyra-
midal. The two phosphorus atoms and the CO and Cl-
(1) ligand mark the basis of this coordination polyhe-
dron, and Cl(3) is at its apex. The apical Rh-Cl(3) bond
(2.574(4) Å), oriented trans to zirconium, is significantly
longer than the basal Rh-Cl(1) linkage (2.398(3) Å),
which may further indicate a weak electronic Rh‚‚‚Zr
interaction making use of the empty lateral metallocene
acceptor orbital in the heterodimetallic complex 12.
(15) Tetracoordinated Cl(CO)2Rh(PPh2R) complexes typically show
larger 31P NMR δ-values (ca. 13-26 ppm) and substantially increased
1J RhP coupling constants (ca. 115-130 Hz), see ref 7b and: Mann, B.
E.; Masters, C.; Shaw, B. L. J . Chem. Soc. (A) 1971, 1104.
(16) Vastag, S.; Heil, B.; Marko, L. J . Mol. Catal. 1979, 5, 189.
(17) Silver, M. E.; Eisenstein, O.; Fay, R. C. Inorg. Chem. 1983, 22,
759. Choukroun, R.; Dahan, F.; Gervais, D. J . Organomet. Chem. 1984,
266, C33. Engelhardt, M. L.; J acobsen, G. E.; Raston, C. L.; White, A.
H. J . Chem. Soc., Chem. Commun. 1984, 220. Gambarotta, S.; Strologo,
S.; Floriani, C.; Chiesi-Villa, A.; Guastini, C. J . Am. Chem. Soc. 1985,
107, 6278. See for a comparison: Halloway, C. E.; Walker, I. M.;
Melnik, M. J . Organomet. Chem. 1987, 321, 143.
(14) (a) Hayashi, T.; Konishi, M.; Kobori, Y.; Kumada, M.; Higuchi,
T.; Hirotsu, K. J . Am. Chem. Soc. 1984, 106, 158. (b) See also:
Okukado, N.; Van Horn, D. E.; Klima, W. L.; Negishi, E. Tetrahedron
Lett. 1978, 1027.
(18) (a) The Zr-Rh sum of covalent metal radii is 2.94 Å: Slater, J .
C. J . Chem. Phys. 1964, 41, 3199. Moeller, T. Inorganic Chemistry;
Wiley: New York, 1982; pp 70-71. (b) The Zr-Rh sum of covalent
radii in typical organometallic systems is ca. 2.71 Å (see ref 21a).

1258 Organometallics, Vol. 19, No. 7, 2000
Bosch et al.
F igu r e 2. Molecular structure of the Zr/Rh complex 12
(with unsystematical atom-numbering scheme). Selected
bond lengths (Å) and angles (deg) (for additional values
see text): Rh-Zr 2.997(2), Rh-P 2.311(3) Rh-Cl1 2.398-
(3), Rh-Cl3 2.574(4), Rh-C30 1.84(2), C30-O30 1.13(2),
P-C1 1.812(10), P-C11 1.820(10), P-C21 1.820(10),
Zr-Cl1 2.556(3), Zr-Cl2 2.504(4), Zr-CCp 2.503(10);
P-Rh-P* 158.4(1), P-Rh-Cl1 87.5(1), P-Rh-Cl3 100.7-
(1), Cl1-Rh-Cl3 96.1(1), P-Rh-C30 88.6(1), Cl1-Rh-C30
159.4(4), Cl3-Rh-C30 104.5(4), Rh-C30-O30 179.7(12),
Rh-P-C1 100.3(3), Rh-P-C11 120.3(3), Rh-P-C21 119.2-
(4), C1-P-C11 106.7(5), C1-P-C21 106.9(5), C11-P-C21
102.1(5), Rh-Cl1-Zr 74.4(1), Cl1-Zr-Cl2 80.3(1).
F igu r e 3. Molecular structure of 13 (with unsystematical
atom-numbering scheme). Selected bond lengths (Å) and
angles (deg) (for additional values see text): Zr-C1 2.250-
(4), Zr-C2 2.268(5), Zr-CCp1 2.526(5), Zr-CCp2 2.535(5),
P1-C10 1.821(4), P1-C21 1.841(4), P1-C31 1.840(4),
P2-C15 1.820(4), P2-C41 1.839(4), P2-C51 1.821(4);
C1-Zr-C2 92.9(2), Zr-C10-P1 122.5(2), Zr-C15-P2
122.8(2), C10-P1-C21 101.6(2), C10-P1-C31 100.3(2),
C21-P1-C31 100.9(2), C15-P2-C41 101.4(2), C15-P2-
C51 101.2(2), C41-P2-C51 100.9(2).
Sch em e 3
The phosphines are coordinated trans to each other
at Rh (d(Rh-P) ) 2.311(3) Å).19,20 The corresponding
bond angles at the base of the distorted square pyra-
mid are 158.4(1)° (P-Rh-P*), 87.5(1)° (P-Rh-Cl(1)),
159.4(4)° (Cl(1)-Rh-C(30)), and 88.6(1)° (P-Rh-C(30)).
The remaining bond angles to the apical chloride ligand
amount to 96.1(1)° (Cl(1)-Rh-Cl(3)), 100.7(1)° (P-Rh-
Cl(3)), and 104.5(4)° (C(30)-Rh-Cl(3)). The Rh-C(30)
bond length of the rhodium-carbonyl moiety is 1.84(2)
Å; the C(30)-O(30) bond is short at 1.13(2) Å.
Complex 5 was then converted to (Cp-PPh2)2Zr(CH3)2
(13) by treatment with 2 equiv of methyllithium analo-
gously as described in the literature.10 We have char-
acterized complex 13 by an X-ray crystal structure
analysis (see Figure 3). It was then reacted with
hydrido(carbonyl)tris(triphenylphosphine)rhodium (14)
in toluene solution at 0 °C. A dark red solution is formed
instantaneously with evolution of methane. The liber-
ated triphenylphosphine was difficult to separate from
the resulting organometallic product (15). Eventually
a clean microcrystalline sample of 15 was obtained from
toluene/ether (1:1). We assume that a Cp-PPh2-bridged
zirconium,rhodium (Zr-Rh) complex containing a metal-
metal bond was formed, similar to the [(alkoxy)phos-
phine]Zr-Rh systems previously reported by P. Wolc-
zanski et al.21 Complex 15 exhibits a IR ν˜(CO) band at
1977 cm-1 in dichloromethane solution. The 13C NMR
resonance of the Rh-CtO moiety is observed at δ 195.5
ppm (ddt, with coupling constants of 1J RhC ) 80 Hz and
2J PC ) 9 and 12 Hz). There is a single 1H NMR
Zr-CH3 resonance at δ -0.83 ppm (corresponding 13C
NMR signal at δ 29.1 ppm). Complex 15 exhibits two
31P NMR resonances in a 2:1 intensity ratio at δ
1
27.2 ppm (C5H4-PPh2, J RhP ) 162 Hz) and δ 45.5
1
(Rh-PPh3, J RhP ) 111 Hz) with a geminal coupling
2
constant of J PP ) 37 Hz. Complex 15 exhibits four
separate C5H4 1H NMR resonances at δ 6.61, 6.40, 5.40,
and 4.11 (with corresponding 13C NMR signals at δ
116.31, 116.29, 108.3, and 103.4; ipso-carbon atom
signal of the symmetry-equivalent C5H4-PPh2 ligands
at δ 107.8 ppm).
Complex 15 is an active hydroformylation catalyst.22
It was shown to catalyze the formation of heptanals
from 1-hexene in a temperature range of ca. 22-120 °C.
Above ca. 50 °C excellent activities are obtained. The
maximum initial turnover frequency of >600 mol alde-
hyde/(mol catalyst‚h) for 1-hexene hydroformylation was
found at 80 °C, 20 bar CO/H2 (1:1) pressure with a
substrate-to-catalyst ratio of 400. This is in the very
high activity range and equals or exceeds some of the
best Rh/chelate phosphine systems (see Chart 3)23
operating in organic solvents. n/iso ratios of about 3 are
obtained at the catalyst system 15. This is in the range
(19) Hitchcock, P. B.; McPartlin, M.; Mason, R. J . Chem. Soc., Chem.
Commun. 1969, 1367. Anderson, M. P.; Pignolet, L. H. Inorg. Chem.
1981, 20, 4101. Farranone, F.; Bruno, G.; Tresoldi, G.; Farranone, G.;
Bombieri, G. J . Chem. Soc., Dalton Trans. 1981, 1651.
(20) Bakhmutov, V. I.; Visseaux, M.; Baudry, D.; Dormond, A.;
Richard, P. Inorg. Chem. 1996, 35, 7316.
(22) Pruett, R. L. Adv. Organomet. Chem. 1979, 17, 1. Pignolet, L.
H., Ed. Homogeneous Catalysis with Metal Phosphine Complexes;
Plenum Press: New York, 1983.
(21) (a) Ferguson, G. S.; Wolczanski, P. T.; Parkanyi, L.; Zonnevylle,
M. C. Organometallics 1988, 7, 1967. Slaughter, L. M.; Wolczanski,
P. T. J . Chem. Soc., Chem. Commun. 1997, 2109. (b) Trinquier, G.;
Hoffmann, R. Organometallics 1984, 3, 370. Hembre, R. T.; Scott, C.
P.; Norton, J . R. J . Am. Chem. Soc. 1987, 109, 4368.
(23) Casey, C. P.; Whiteker, G. T.; Melville, M. G.; Petrovich, L. M.;
Gavney, J . A., J r.; Powell, D. R. J . Am. Chem. Soc. 1992, 114, 5535.
Kranenburg, M.; van der Burgt, Y. E. M.; Kamer, P. C. J .; van
Leeuwen, P. W. N. M.; Goubitz, K.; Fraanje, J . Organometallics 1995,
14, 3081.

Zr/ Pd and Zr/ Rh Catalyst Precursors
Organometallics, Vol. 19, No. 7, 2000 1259
Ch a r t 3. Str u ctu r es of th e Ch ela te P h osp h in es 16
a n d 17
Exp er im en ta l Section
All reactions were carried out under argon using Schlenk-
type glassware or in a glovebox. Solvents were dried and
distilled under argon prior to use. For further general informa-
tion including a list of instrumentation used for the spectro-
scopic and physical characterization of the compounds see ref
26. The complexes (Cp-PPh2)2ZrCl2 (5) and (Cp-PPh2)2Zr(CH3)2
(13) were prepared analogously as described in the literature.10
Rea ction of (Cp -P P h 2)2Zr Cl2 (5) w ith (P h CN)2P d Cl2,
Syn th esis of 7. Two separate solutions of (Cp-PPh2)2ZrCl2 (5,
572 mg, 0.87 mmol) and (PhCN)2PdCl2 (6, 333 mg, 0.87 mmol),
each in 30 mL of dichloromethane, were cooled to -78 °C and
then slowly added dropwise simultaneously to 20 mL of
dichloromethane at -78 °C. The mixture was stirred at -78
°C for 1 h and then warmed to room temperature. After 12 h
the reaction mixture was reduced to a volume of 10 mL in
vacuo, and the product precipitated by the addition of pentane
(20 mL). The pale yellow solid was collected by filtration and
dried in vacuo to yield 620 mg (85%) of 7. Mp: 260 °C. Anal.
observed for many other Rh hydroformylation systems,
but it is far away from the optimum,24 such as, for
example, achieved with the ligand examples 16 and 17
shown in Chart 3.
Con clu sion s
In the monometallic ligand systems (Cp-PPh2)2ZrX2
(X ) Cl or CH3), the bulky Ph2P-substituents are
oriented far away from each other in the lateral sectors
of the bent metallocene wedge (bis-lateral:anti-confor-
mation). However, rotation about the Zr-Cp vector is
a low activation energy process25 and thus allows for
an adjustment of the actual bite angle over a very broad
range, when these systems function as organometallic
chelate phosphines in early-late heterodimetallic com-
plexes. In this respect, the bent metallocene chelate
phosphines are fundamentally different from their
ordinary “linear” metallocene chelate phosphine rela-
tives, such as, for example, dppf13 (10, see Chart 2). This
great variability and adjustment of the P-M-P angle
is illustrated by the two structurally characterized
systems described in this study: the Zr/Pd complex 7
exhibits a P-Pd-P angle of 96°, whereas the Zr/Rh
complex 15 shows a 158° angle. The pronounced con-
formational flexibility of the group 4 bent metallocenes
makes an a priori adjustment of the optimal chelate bite
angle difficult, but this high conformational freedom
apparently allows some systems to adjust to achieve
either a high selectivity (observed in cross-coupling at
the catalyst originating from the Zr/Pd system 7) or high
reactivity (Zr/Rh hydroformylation catalyst 15). Care-
fully adding a few conformational restraints by using
ansa-metallocene frameworks may lead to a way to
generate novel catalyst systems of this type with much
improved reactivity/selectivity profiles.
The selected examples 7, 12, and 15 also illustrate
nicely the broad range of support that the group 4 bent
metallocene unit can provide for the adjacent late
transition metal in such early-late heterodimetallic
complexes. In 7 the (Cp-PPh2)2ZrCl2 unit merely serves
as a flexible chelate phosphine ligand, but in 12 and 15
it actively interacts by means of additional bridging or
the formation of a metal-metal bond with the Rh-center
and alters and determines its coordinative and elec-
tronic features substantially. Such effects will probably
be very useful in catalyst design and control of catalyst
action, as indicated by the high hydroformylation activ-
ity found with the heterodimetallic Zr/Rh catalyst 15.
C
34H28P2Cl4PdZr (838.0): calcd C 48,73, H 3.37; found C 48.75,
H 3.46. 1H NMR (dichloromethane-d2, 600 MHz): δ ) 7.63
(m, 8H), 7.56 (pt, 4H), 7.43 (pt, 8H) (o,p,m-Ph), 6.91 (m, 4H),
6.34 (m, 4H) (C5H4). 13C NMR (dichloromethane-d2, 150
1
2
MHz): δ ) 131.1 (d, J PC ) 60 Hz), 135.0 (d, J PC ) 11 Hz),
3
132.5 (s), 129.0 (d, J PC ) 12 Hz; ipso-, o-, p-, m-PPh2), 127.5
2
3
1
(d, J PC ) 7 Hz), 121.4 (d, J PC ) 9 Hz), 114.8 (dd, J PC ) 46
Hz, J PC ) 7 Hz; R-, â-, ipso-C of C5H4). 31P NMR (dichlo-
3
romethane-d2, 81 MHz): δ ) 29.0. IR (KBr): ν˜ ) 3086, 2917,
2851, 1482, 1435, 1182, 1095, 1041, 828 cm-1. X-ray crystal
structure analysis of 7: single crystals from dichloromethane,
formula C34H28P2Cl4ZrPd‚2/2CH2Cl2, M ) 922.85, light yellow
crystal 0.35 × 0.10 × 0.05 mm, a ) 9.443(1) Å, b ) 14.478(1)
Å, c ) 14.517(1) Å, R ) 100.42(1)°, â ) 99.47(1)°, γ ) 93.59-
(1)°, V ) 1916.6(3) Å3, Fcalc ) 1.599 g cm-3, µ ) 12.67 cm-1
,
empirical absorption correction via SORTAV (0.666 e T e
0.939), Z ) 2, triclinic, space group P1h (No. 2), λ ) 0.71073 Å,
T ) 198 K, ω and æ scans, 25 158 reflections collected ((h,
(k, (l), [(sin θ)/λ] ) 0.72 Å-1, 11 066 independent (Rint ) 0.043)
and 8862 observed reflections [I g 2 σ(I)], 433 refined
parameters, R ) 0.047, wR2 ) 0.114, max. residual electron
density 1.36 (-0.87) e Å-3, occupancies for the solvent mol-
ecules refined and then fixed to 0.5, hydrogens calculated and
refined as riding atoms, data set collected with a Nonius Kappa
CCD on a rotating anode generator FR591.26
Ca ta lytic Cr oss-Cou p lin g Rea ction , F or m a tion of 8
a n d 9. A sample of the Zr/Pd complex 7 (0.04 mmol) was
dissolved in 10 mL of diethyl ether. n-Dodecane (0.5 mL) was
added as an internal standard for the GLC analysis and 4.0
mmol of bromobenzene or p-bromoanisol, respectively. The
mixture was cooled to -78 °C, and 8.8 mL (8.0 mmol) of a 0.91
M ethereal sec-butylmagnesium bromide solution was added.
The mixture was then quickly heated to the reaction temper-
ature and the progress of the reaction monitored by analyzing
aliquots of the solution. For that purpose 1 mL samples of the
mixture were quenched by treatment with 10% aqueous HCl
(1 mL), the phases separated, and the organic phases dried
over Na2SO4. The remaining inorganic products were removed
by filtration through a 5 × 0.3 cm silica gel column. The clear
solution was then analyzed by gas chromatography (25 m HP5
column, temp program 40-280 °C, 10 °C min-1). The adduct/
product ratio and the product isomer ratio were determined
(26) Programs used: EXPRESS: Nonius B.V., 1994. COLLECT:
Nonius B.V., 1998. MolEN: Fair, K. Enraf Nonius B.V., 1990. Denzo-
SMN: Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307-
326. SORTAV: Blessing, R. H. Acta Crystallogr. 1995, A51, 33-37; J .
Appl. Crystallogr. 1997, 30, 421-426. SHELXS-86 and SHELXS-97:
Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467-473. Sheldrick, G.
M. Universita¨t Go¨ttingen, 1997. SHELXL-93 and SHELXL-97: Sheld-
rick, G. M. Universita¨t Go¨ttingen, 1997. SCHAKAL: Keller, E.
Universita¨t Freiburg, 1997. DIAMOND: Brandenburg, K. Universita¨t
Bonn, 1996 (plots are shown at the 50% probability level).
(24) Cornils, B., Herrmann, W. A., Eds. Aqueous-Phase Organome-
tallic Catalysis: Concepts and Applications; Wiley-VCH: Weinheim,
1998.
(25) Erker, G.; Mu¨hlenbernd, T.; Benn, R.; Rufinska, A.; Tsay, Y.-
H.; Kru¨ger, C. Angew. Chem. 1985, 97, 336; Angew. Chem., Int. Ed.
Engl. 1985, 24, 321. Erker, G.; Aulbach, M.; Knickmeier, M.; Wing-
bermu¨hle, D.; Kru¨ger, C.; Nolte, M.; Werner, S. J . Am. Chem. Soc.
1993, 115, 4590. Knickmeier, M.; Erker, G.; Fox, T. J . Am. Chem. Soc.
1996, 118, 9623.

1260 Organometallics, Vol. 19, No. 7, 2000
Bosch et al.
by integration relative to the internal standard n-dodecane.
The results from a series of representative experiments are
listed in Table 1.
correction via ψ-scan data (0.964 e C e 0.999), Z ) 2, triclinic,
space group P1h (No. 2), λ ) 0.71073 Å, T ) 223 K, ω/2θ scans,
6583 reflections collected (-h, (k, (l), [(sin θ)/λ] ) 0.62 Å-1
,
6187 independent (Rint ) 0.031) and 4889 observed reflections
[I g 2 σ(I)], 354 refined parameters, R ) 0.054, wR2 ) 0.171,
max. residual electron density 1.08 (-0.94) e Å-3, hydrogens
calculated and refined as riding atoms, data set collected with
an Enraf-Nonius CAD4 with a sealed-tube generator.26
Rea ction of (Cp -P P h 2)2Zr (CH3)2 (13) w ith H(CO)Rh -
(P P h 3)3 (14), F or m a tion of 15. Toluene (50 mL) was added
at 0 °C to a solid mixture of 13 (930 mg, 1.5 mmol) and 14
(1.38 g, 1.5 mmol). The solution turned dark red immediately.
After 1 h a yellowish precipitate was removed by filtration and
the solvent removed from the remaining clear solution in
vacuo. Workup of the product turned out to be very problematic
since removal of the PPh3 was severly hampered by the
sensitivity of 15. Several attempts resulted in complete
decomposition to yield a black oil or a dark brown powder of
an unknown composition. In a successful experiment a part
of the crude product (300 mg), which still contained 2 molar
equiv of PPh3, was dissolved in a toluene/diethyl ether (1:1)
mixture and crystallized at -20 °C. To remove the phosphine,
the precipitated red-brown microcrystalline solid was quickly
collected by filtration and dried in vacuo. Mp: 134 °C (decomp).
Due to small amounts of PPh3 that remained, it was difficult
to obtain the very sensitive complex 15 completely analytically
pure. Anal. C54H46P3ORhZr (998.0): calcd C 64.99, H 4.65;
found C 64.03, H 4.77. 1H NMR (dichloromethane-d2, 600
MHz): δ ) 7.38, 7.35, 7.28, 7.18, 7.16, 7.05, 6.86 (m, 35H, PPh2,
PPh3), 6.61, 6.40, 5.40, 4.11 (m, each 2H, C5H4), -0.83 (s, 3H,
CH3). 13C NMR (dichloromethane-d2, 150 MHz): δ ) 195.5
(ddt, 1J RhC ) 80 Hz, 2J PC ) 12 and 9 Hz, CtO), 140.3 (dt, 1J PC
Rea ction of (Cp -P P h 2)2Zr Cl2 (5) w ith [Rh (CO)2Cl]2 (11),
P r ep a r a tion of 12. (a ) P r ep a r a tion in Dich lor om eth a n e.
A solution of complex 5 (340 mg, 0.51 mmol) in 30 mL of
dichloromethane was added dropwise at 0 °C to a solution of
11 (100 mg, 0.254 mmol) in dichloromethane. The reaction
mixture was allowed to warm to room temperature and then
stirred for 24 h. The mixture was concentrated in vacuo to a
volume of 5 mL, and then pentane (20 mL) was added to
precipitate further product. The solid was collected by filtration
and dried in vacuo to yield 375 mg (89%) of 12. The poorly
soluble complex was recrystallized from tetrahydrofuran at
-20 °C to give single crystals for the X-ray crystal structure
analysis of 12: formula C35H28OP2Cl3ZrRh‚4C4H8O, M )
1115.41, yellow crystal 1.20 × 0.25 × 0.10 mm, a ) 10.220(1)
Å, b ) 18.962(4) Å, c ) 13.161(1) Å, â ) 103.09(1)°, V ) 2484.2-
(6) Å3, Fcalc ) 1.491 g cm-3, µ ) 8.13 cm-1, no empirical
absorption correction due to the shape of the used crystal, Z
) 2, monoclinic, space group P21/m (No. 11), λ ) 0.71073 Å, T
) 223 K, ω/2θ scans, 4787 reflections collected (-h, -k, (l), [(sin
θ)/λ] ) 0.59 Å-1, 4521 independent (Rint ) 0.083) and 2520
observed reflections [I g 2 σ(I)], 344 refined parameters, R )
0.069, wR2 ) 0.171, max. residual electron density 1.09 (-0.94)
e Å-3, hydrogens calculated and refined as riding atoms,
cutting of the crystal leads to a extreme broadening of the
profiles in the ω-scans, data set collected with an Enraf-Nonius
CAD4 with a sealed-tube generator.26
(b) P r ep a r a tion in Tolu en e. A solution of 5 (220 mg, 0.33
mmol) in toluene (20 mL) was added dropwise at -60 °C to a
solution of 11 (65 mg, 0.167 mmol) in 20 mL of toluene. The
mixture was stirred for 1 day at room temperature. Pentane
(10 mL) was added to the reaction mixture that contained a
bright yellow solid. The precipitate was collected by filtration,
washed with toluene and pentane, and dried in vacuo to give
262 mg (86%) of 12. Mp: 177 °C (decomp). Isolated samples
of complex 12 always contained some solvent (here ca. 1 equiv
of toluene). It was, therefore, difficult to get 12 analytically
pure. Anal. C35H28P2OCl3RhZr‚C7H8 (919.2): calcd C 54.88, H
3.95; found C 53.94, H 3.72. 1H NMR (dichloromethane-d2, 200
MHz): δ ) 8.26 (m, 4H), 8.11 (m, 4H), 7.5 (br m, 12H) (Ph),
6.60, 6.45, 6.05, 5.84 (m, each 2H, C5H4). 13C NMR (dichlo-
romethane-d2, 150 MHz): δ ) 135.1, 132.2, 129.6-129.3
(several signals, Ph), 121.1, 116.4, 116.1, 105.3 (C5H4), ipso-C
3
1
) 19.8 Hz, J PC ) 3.9 Hz, ipso C of PPh2), 139.7 (td, J PC
)
3
1
24.2 Hz, J PC ) 3.9 Hz, ipso-C of PPh3), 139.2 (t, J PC ) 9.6
Hz, ipso-C of PPh2), 134.4 (t, J PC ) 8.4 Hz, PPh2), 134.3 (d,
J PC ) 13.4 Hz, PPh3), 132.7 (t, J PC ) 7.5 Hz, PPh2), 129.4 (s,
p-C of PPh3), 128.5 (s, p-C of both PPh2), 127.4 (d, J PC ) 9.0
Hz, PPh3), 116.3 (t, J PC ) 3.2 Hz, C5H4), 116.3 (t, J PC ) 5.7
Hz, C5H4), 108.3 (t, J PC ) 3.8 Hz, C5H4), 107.8 (ddd, J ) 20.4,
18.5, and 9.6 Hz, ipso-C of C5H4), 103.4 (t, J ) 4.5 Hz, C5H4),
29.1 (s, CH3) ppm. GHMBC NMR (dichloromethane-d2, 600
MHz): δ ) [195.5 (Rh-CtO)/-0.83 (Zr-CH3)], [116.3 (C5H4)/
6.61, 5.40, 4.11 (C5H4), -0.83 (Zr-CH3)], [108.3 (C5H4)/6.61
(C5H4)], [107.8 (ipso C of C5H4)/4.11 (C5H4), 7.3 (Ph-H)], [103.4
(C5H4)/6.61, 6.40, 5.40 (C5H4)], [29.1 (Zr-CH3)/-0.83 (Zr-
CH3)]. 31P NMR (dichloromethane-d2, 81 MHz): δ ) 46.5 (dt,
resonances of the poorly soluble complex 12 were not observed.
2
1
1J RhP ) 111 Hz, J PP ) 37 Hz, Rh-PPh3), 27.2 (dd, J RhP
)
1
31P NMR (dichloromethane-d2, 81 MHz): δ ) 8.1 (d, J RhP
)
162 Hz, 2J PP ) 37 Hz, PPh2). IR (CH2Cl2): ν˜ ) 1977 cm-1 (Rh-
CtO).
93 Hz). IR (KBr): ν˜ ) 1990 cm-1 (Rh-CtO).
X-r a y Cr ysta l Str u ctu r e An a lysis of (Cp -P P h 2)2Zr -
(CH3)2 (13). Complex 13 was prepared analogously as de-
scribed by W. Tikkanen et al.10 by treatment of 5 (4.65 g, 7.1
mmol) in 150 mL of toluene with 30 mL of a 0.47 M solution
of methyllithium (14.1 mmol) in ether at -78 °C. After 4 h
the mixture was filtered at room temperature and the filtrate
concentrated in vacuo to a volume of 10 mL. Pentane (50 mL)
was added. The product was collected by filtration, washed
with pentane, and dried in vacuo to yield 3.72 g (85%) of 13.
1H NMR (CD2Cl2, 600 MHz): δ ) 7.3 (m, 20H, Ph), 6.12 and
Hexen e Hyd r ofor m yla tion Ca ta lyzed by th e Zr /Rd
Com p lex 15. 1-Hexene was purified by stirring over Na/K
alloy and then distilled. The n-dodecane used as an internal
standard for the GLC analysis was dried over 4 Å molecular
sieves and distilled prior to use. The hydroformylation reaction
was carried out in a special steel autoclave fitted with a
pressurized dropping funnel and a capillary and valve for
taking samples at any chosen time during the reaction. A 1:1
mixture of CO and H2 was employed.
Gen er a l P r oced u r e. In a typical experiment 0.08 mmol
of the catalyst 15 was employed with 4.0 mL (32.0 mmol) of
1-hexene (i.e., a substrate-to-catalyst ratio of 400:1) in the
presence of 0.5 mL (4.4 mmol) of the internal standard
n-dodecane. The autoclave was charged with a THF solution
(5-10 mL) of the Zr/Rh catalyst. The system was then
pressurized (20 bar) and the autoclave thermostated at the
chosen temperature. 1-Hexene and n-dodecane dissolved in ca.
10 mL of THF was then added through the dropping funnel,
and the reaction started with stirring. Samples of ca. 1 mL
were taken from time to time under pressure. The system was
repressurized as soon as the pressure had dropped by 5 bar
during the reaction. The samples were quenched by treatment
4
5.97 (m, each 4H, C5H4), -0.41 (br t, J PH ) 0.5 Hz, Zr-CH3).
1
13C NMR (CD2Cl2, 150 MHz): δ ) 138.7 (d, J PC ) 11 Hz),
2
3
134.0 (d, J PC ) 21 Hz), 129.2 (s), 128.7 (d, J PC ) 8 Hz; ipso-,
1
2
o-, p-, m-PPh2), 117.9 (d, J PC ) 11 Hz), 116.1 (d, J PC ) 12
3
Hz), 113.9 (br s; ipso-, R- and â-C5H4), 32.4 (t, J PC ) 6 Hz,
Zr-CH3). 31P NMR (CD2Cl2): δ ) -18.9. Single crystals were
obtained from
a solution of 13 in toluene containing a
supernatant pentane solvent phase. Diffusion of the two
phases overnight at -20 °C gave large crystals of 13: formula
C
36H34P2Zr, M ) 619.79, colorless crystal 0.50 × 0.40 × 0.10
mm, a ) 9.273(1) Å, b ) 12.326(1) Å, c ) 14.344(2) Å, R )
102.33(1)°, â ) 97.48(1)°, γ ) 102.94(1)°, V ) 1533.5(3) Å3,
Fcalc ) 1.342 g cm-3, µ ) 4.86 cm-1, empirical absorption

Zr/ Pd and Zr/ Rh Catalyst Precursors
Organometallics, Vol. 19, No. 7, 2000 1261
with 1 mL of a saturated aqueous NH4Cl solution. The phases
were separated and the organic phase dried over MgSO4.
Remaining inorganic products were removed by filtration
through a 5 × 0.4 cm silica gel column. The products and the
progress were analyzed by gas chromatography (25 m HP5
column, 3 min at 40 °C, temperature programmed 10 °C min-1
to 150 °C, followed by 20 °C min-1 to 280 min. The product
ratios were determined by integration relative to the n-
dodecane standard, and the response factors of the single
components were separately determined. 1-Hexene/2-hexene
and n-hexane were not baseline separated under these condi-
tions and monitored together. The accuracy of the values at
higher conversions was estimated at ca. (10%. Series of
experiments were carried out at four temperatures. The initial
TOF (mol product/(mol cat.‚h)) was determined in each case
at the early stages of the reaction using the increase of the
relative product yield between the second and third samples
taken. The following results were obtained: expt 1, 43 °C, TOF
24, n/iso 3.1; expt 2, 55 °C, TOF 305, n/iso 2.8; expt 3, 80 °C,
TOF 630, n/iso 3.0; expt 4, 120 °C, TOF 465, n/iso 3.2. Further
details about these experiments are given in the Supporting
Information.
Ackn owledgm en t. Financial support from the Fonds
der Chemischen Industrie is gratefully acknowledged.
S.K. thanks the Academy of Finland for financial
support.
Su p p or tin g In for m a tion Ava ila ble: Details of the X-ray
crystal structure analyses including complete listings of bond
lengths and angles, thermal parameters, atomic positional
parameters, and the hydroformylation experiments using
complex 15 as a catalyst. This material is available free of
charge via the Internet at http://pubs.acs.org.
OM990685F