Chelating phosphines with low coordinated phosphorus atoms: Part I. Phosphaalkenes associated with phosphine moieties - X-ray structure of cis-(CO)4Mo[ortho-Ph2P-C6H 4-CH=P(t-Bu3C6H2)]·C 7H16

Article abstract of DOI:10.1016/S0022-328X(01)00654-4

Condensation of ortho-diphenylphosphinobenzaldehyde with 2,4,6-tri-t-butyl-phenylphosphine yields the λ²,λ³-diphosphorus chelating agent 2a with an E-configurated phosphaalkene unit as indicated by the analysis of the NMR data. On irradiation with UV light 2a is transformed to the Z-isomer (2b). E-2a forms stable Mo(0), Pd(II) and Pt(II) chelate complexes (3-5). The X-ray structure of the molybdenum complex 3·C₇H₁₆ (space group P2₁2₁2₁) has been determined showing the phosphaalkene moiety to be coordinated in a η¹-mode to molybdenum within a distorted six-membered chelate ring.

Full text of DOI:10.1016/S0022-328X(01)00654-4

Journal of Organometallic Chemistry 626 (2001) 106–112
www.elsevier.nl/locate/jorganchem
Chelating phosphines with low coordinated phosphorus atoms
Part I. Phosphaalkenes associated with phosphine
moieties — X-ray structure of
cis-(CO)4Mo[ortho-Ph2PꢀC6H4ꢀCHꢁP(t-Bu3C6H2)]·C7H16
David J. Brauer, Christian Liek, Othmar Stelzer *
Fachbereich 9, Anorganische Chemie, Bergische Uni6ersita¨t-GH Wuppertal, Gaußstraße 20, D-42097 Wuppertal, Germany
Received 9 November 2000; received in revised form 4 December 2000; accepted 28 December 2000
Abstract
Condensation of ortho-diphenylphosphinobenzaldehyde with 2,4,6-tri-t-butyl-phenylphosphine yields the l2,l3-diphosphorus
chelating agent 2a with an E-configurated phosphaalkene unit as indicated by the analysis of the NMR data. On irradiation with
UV light 2a is transformed to the Z-isomer (2b). E-2a forms stable Mo(0), Pd(II) and Pt(II) chelate complexes (3–5). The X-ray
structure of the molybdenum complex 3·C7H16 (space group P212121) has been determined showing the phosphaalkene moiety to
be coordinated in a h1-mode to molybdenum within a distorted six-membered chelate ring. © 2001 Elsevier Science B.V. All
rights reserved.
Keywords: Phosphaalkenes; Diphenylphosphino groups; Mo(0), Pd(II), Pt(II) complexes; Ligand properties; X-ray structure
1. Introduction
The synthesis and coordination chemistry of
monodentate organophosphorus compounds contain-
ing low coordinated phosphorus atoms (e.g. phos-
phaalkenes, phosphaalkynes and l3-phosphinines) have
been developed in great detail in the past decades [1,2].
In contrast to the vast number of polydentate l3-phos-
phine ligands [3] there are only a very few reports in the
literature on di- and tridentate ligands containing phos-
phorus in low coordination numbers, e.g. A–C [4,5].
Chelating agents of type D comprise donor proper-
For the synthesis of l2,l3-phosphorus donor systems
ties of phosphaalkenes and tertiary phosphines in one
D
aromatic phosphine ligands with appropriate
molecule and should therefore show interesting coordi-
nation chemistry. There is only one report (patent
literature) [6] claiming the application of a type D
ligand in Pd catalyzed copolymerization of CO and
olefins. No experimental details for the preparation and
characterization of the ligand are given, however.
OꢁC(R) functional groups in the ortho-position to the
PR¦ group, e.g. E, may be employed as starting materi-
2
als. Phosphines of the type E with R¦=Ph and R=H,
Me, Pr have already been reported in the literature [7a].
Recently, we have developed a convenient high yield
synthesis for these ortho-functionalized derivatives of
triphenylphosphine [7b].
Due to the pronounced reactivity of the prochiral
PꢁC double bond [1,8,9], ligands of the type D may be
used for the synthesis of novel chiral chelating phos-
* Corresponding author. Tel.: +49-202-439-2517; fax: +49-202-
439-3053.
E-mail address: stelzer@uni-wuppertal.de (O. Stelzer).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)00654-4

D.J. Brauer et al. / Journal of Organometallic Chemistry 626 (2001) 106–112
107
Scheme 1.
Scheme 2.
phines. Thus, addition of proton active compounds HX
(X=OR, NR2) yields chiral chelating agents F while by
[2+4]-cycloaddition of 1,3-dienes mono- or bicyclic
phosphine ligands G (Z=2H, CH2, CH2ꢀCH2, O) are
accessible (Eqs. (1a) and (1b) in Scheme 1).
The prochiral phosphaalkenes D are thus a potential
source of optically active phosphines provided that face
selectivity can be achieved by chiral substituents R, R%
or R¦ during the additions and cycloadditions. Here we
report on the synthesis of Ph2P derivatives of D with a
C(H)ꢁPR% group.
signed by comparison with the corresponding data of H
[10] and related compounds and by making use of
13C-DEPT-NMR spectra. For the carbon atom of the
PꢁC double bond a resonance at lC=174.5 is ob-
served showing a doublet of doublet PꢀC coupling fine
3
structure (1J(PC)=23.4, J(PC)=13.2 Hz).
Correspondingly the 1H-NMR resonance of the
vinylic a-hydrogen atom (lH=9.29) shows doublet of
doublet splitting (2J(PH)=24.7, 4J(PH)=5.8 Hz).
These data are in agreement with the structure pro-
posed for 2a with an E-configurated phosphaalkene
substituent in ortho-position to the Ph2P group. The
assignment of an E-configuration to the ArPꢁC(H) unit
in 2a is supported by comparison with the pertinent
NMR data of the E-isomers of phosphaalkenes of type
H [10,13].
2. Syntheses of the phosphaalkene-phosphine ligands
2a, 2b
For the synthesis of the ligand 2a easily accessible
ortho-diphenylphosphino benzaldehyde (1a) [7] was
used as the starting material. The phosphaalkene moi-
ety could be introduced by the Yoshifuji procedure [10]
employing 2,4,6-t-Bu3C6H2-PH2 (1b) [11] as the pri-
mary phosphine (Eq. (2) in Scheme 2). After workup
conventional of the reaction mixture the phos-
phaalkene-phosphine ligand 2a was obtained in high
yield as a yellow crystalline solid.
The mass spectrum of 2a shows the peak for the
molecular ion at m/e=550 and peaks for fragment ions
at m/e=494 (M+−C4H8), 474 (M+−C6H4) with the
basis peak at m/e=305 corresponding to M+−t-
Bu3C6H2.
On irradiation of 2a in benzene solution with a
mercury lamp photoisomerization to 2b, the Z-isomer
In the 31P{1H}-NMR spectrum 2a shows two dou-
blets at lP=268.2 and −14.0 (4J(PP)=20.4 Hz). The
lP value of the low field resonance is in the range
typical for phosphaalkenes RꢀPꢁCꢀH)R% bearing aro-
matic or aliphatic substituents R and R% [12]. The
resonance at lP=268.2 appears as a doublet of dou-
blets due to additional PꢀH coupling in the 31P-NMR
spectrum (2J(PH)=24.7 Hz) with broadened center
lines. The 13C{1H}-NMR signals of 2a could be as-
Scheme 3.

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D.J. Brauer et al. / Journal of Organometallic Chemistry 626 (2001) 106–112
states and coordination geometries have been synthe-
sized. Analysis of the IR and NMR spectroscopic data
of the complexes obtained should reveal the bonding
mode and the ligand properties of this novel l2,l3-phos-
phorus donor system.
Thus on reaction of 2a with C7H8Mo(CO)4 [15] at
ambient temperature red crystalline 3 was obtained in
high yield (Eq. (4a) in Scheme 3). The 31P{1H} reso-
nance of the PPh2 group in 3 (lP=34.5) is shifted by
ca. 50 to low field compared with the corresponding lP
value of 2a. The chemical shift value lP (lP=256.5)
and the small negative coordination chemical shift [16a]
DlP=lP(complex)−lP(ligand)= −11.7 of the sig-
nal of the l2-phosphorus is in agreement with a h1-co-
ordination mode of the phosphaalkene moiety to the
metal [17]. On coordination to Mo(0) the PꢀP coupling
constant of the ligand 2a (4J(PP)=30.5 Hz) increases
significantly (2J(PP)=20.4 Hz in 3). The h1-coordina-
tion mode of the phosphaalkene unit is also supported
by the small coordination chemical shift DlC (−5.4) in
the 13C{1H}-NMR spectrum of 2a.
The IR spectrum of 3 displays four bands in the
carbonyl stretching region at 2027, 1942, 1928, 1920
cm−1 placing 3 with its averaged electronic parameter w
[18a] in between Ph2PH and Ph3P [18b].
The mass spectrum of 3 shows peaks centered at
m/e=757 derived from the molecular ion (m/e=760,
98Mo) by hydrogen abstraction and cluster of peaks for
fragment ions at 730, 703, 676 and 647, which may be
assigned to fragmentation of up to four CO ligands, the
basis peak at m/e=231 corresponding to {t-Bu3C6H2-
CH2}.
,
Fig. 1. Molecular structure of 3·C7H16. Selected bond lengths (A) and
angles (°): MoꢀP(1) 2.4729(14), MoꢀP(2) 2.5239(14), MoꢀC(1)
1.985(6), MoꢀC(2) 1.965(7), MoꢀC(3) 2.039(7), MoꢀC(4) 2.031(8),
P(1)ꢀC(5) 1.668(5), P(1)ꢀC(12) 1.857(5), P(2)ꢀC(7) 1.837(5),
C(5)ꢀC(6) 1.443(7), C(6)ꢀC(7) 1.423(7); P(1)ꢀMoꢀP(2) 81.89(5),
MoꢀP(1)ꢀC(5) 121.8(2), MoꢀP(1)ꢀC(12) 139.3(2), C(5)ꢀP(1)ꢀC(12)
98.7(2),
MoꢀP(2)ꢀC(7)
116.6(2),
P(1)ꢀC(5)ꢀC(6)
131.4(4),
C(5)ꢀC(6)ꢀC(7) 126.5(5), C(5)ꢀC(6)ꢀC(11) 116.3(5).
of 2a occurs. The Z- and E-isomers are obtained in a
ca. 1:1 ratio (Eq. (3) in Scheme 2). UV light induced
E/Z isomerization of phosphaalkenes has been reported
in the literature before [10,13]. The 1H-NMR reso-
nances of the vinylic protons of 2b (lH=9.25,
2J(PH)=35.8, J(PH)=8.9 Hz) and the aromatic hy-
4
drogens of the 2,4,6-t-Bu3C6H2 substituent appear at
higher field (lH=7.61). The same applies for the t-Bu
group in ortho-position, while the signals of the t-Bu
groups in para-position are shifted to low field. The
13C{1H}-NMR resonance of the PꢁC unit in 2b (lC=
159.9) appears at higher field compared with that of 2a.
This is in agreement with the corresponding 13C{1H}-
NMR data obtained for the E/Z isomers of a series of
phosphaalkenes [10,13,14]. As for 2a the carbon atom
of the PꢁC moiety in 2b shows a doublet of doublet fine
structure, the PꢀC coupling constants (1J(PC)=51.4,
3J(PC)=31.0 Hz) being somewhat larger than those in
2a. On isomerization of 2a to 2b the lP value of the
phosphaalkene unit is shifted to high field (lP=248.7).
The assignment of the 13C{1H}-NMR resonances to the
Z-isomer in the reaction mixture obtained after UV
irradiation of 2a was achieved by comparison with the
pertinent NMR data of structurally related phos-
phaalkenes for which E- and Z-isomers are known
[10,13,14]. The 31P{1H} signals of 2b at lP=248.7 and
−13.2 are split into doublets through PꢀP coupling
(4J(PP)=12.7 Hz).
When 2a was allowed to react with palladium(II) or
platinum(II) dichloride in methanol the yellow colored
complexes 4 and 5 of composition MCl2(2a) are formed
(Eq. (4b)). Complex 4 may be obtained alternatively by
the reaction of 2a with K2PdCl4. While the 31P{1H}
resonances of the PPh2 groups in both cases are shifted
to low field (4: lP=22.2, 5: 2.1) a high field shift is
observed for the phosphaalkene moiety (4: lP=194.71,
5: 169.7) with respect to the corresponding data in 2a
(lP=268.2). The 31P{1H} signals show doublet PꢀP
coupling fine structure with a PꢀP coupling constant
typical for cis-MCl2L2 (M=Pd, Pt; L=phosphine lig-
2
2
ands) [19a] (4: J(PP)=24.2, 5: J(PP)=36.0 Hz). The
doublets in the 31P{1H}-NMR spectra of 5 are accom-
panied by 195Pt satellites. For the PPh2 group the
195Ptꢀ31P coupling constant (1J(195Ptꢀ31P)=3175.9 Hz)
is within the range typical for cis-PtCl2L2 complexes
(L=mono- or bidentate phosphine ligands), e.g. cis-
PtCl2(PTol3)2: 3694 Hz [19b]; cis-PtCl2[Ph2Pꢀ
(CH2)nꢀPPh2] (n=1–3): 3078–3420 Hz [19c]. A signifi-
cantly higher value is observed for the 195Ptꢀ31P cou-
pling constant of the phosphaalkene phosphorus atom
(1J(195Ptꢀ31P)=4195.4 Hz) in 5. This value may well be
compared with the one obtained for the structurally
related cis-PtCl2(PEt3)(Mes-P=CPh2) (4294 Hz) [20].
3. Formation of Mo(0), Pd(II), Pt(II) complexes of 2a
In order to demonstrate the capability of 2a to
function as a chelating agent, complexes with transition
metals (Mo(0), Pd(II), Pt(II)) in different oxidation

D.J. Brauer et al. / Journal of Organometallic Chemistry 626 (2001) 106–112
109
prepared according to literature methods. t-BuMe2SiCl
4. X-ray structure of 3
was purchased from Aldrich GmbH.
In order to get detailed information about the coor-
dination mode of the phosphaalkene moiety and the
mutual influence of the l2,l3-phosphorus donor groups
in 3 a crystal structure investigation was performed. A
view of the molecular structure of 3 is presented in Fig.
1, and relevant interatomic distances and angles are
given in the caption of Fig. 1. This study clearly shows
that the chelate ligand 2a is coordinated to the metal by
two |-MoꢀP bonds.
5.1. Synthesis of 2a and 2b
5.1.1. Synthesis of 2a
To a stirred solution of 5.00 g (17.9 mmol) of 1b in
100 ml of THF 17.9 mmol of n-butyllithium dissolved
in n-hexane was added at −78°C. The solution was
allowed to warm up to ambient temperature and 2.70 g
(17.9 mmol) of t-BuMe2SiCl dissolved in 50 ml of THF
were added. After cooling to −30°C the second equiv-
alent of nBuLi (17.9 mmol) was added. Thereafter the
red colored reaction mixture was charged at ambient
temperature with 3.62 g (12.5 mmol) of 1a, dissolved in
50 ml of THF, until the color of the lithium phosphide
had disappeared. All volatiles were then removed in
vacuo (20°C, 0.01 mbar). The residue obtained was
dissolved in ether and washed with 200 ml of a dilute
solution of NaHCO3. Thereafter the organic phase was
separated and dried over MgSO4 and the solvent was
evaporated in vacuo. The yellow colored solid thus
obtained was washed with 20 ml of hot methanol and
recrystallized from a 60:5 ethanol–methanol mixture.
Yield: 5.5 g (80%).
Of these, that formed by the three-coordinate P(1)
,
atom is significantly (0.051(2) A) shorter than that
formed by the four-coordinate P(2) atom. The double
bond character of the P(1)ꢀC(5) interaction is demon-
,
strated by its 1.668(5) A length and the deviation of
,
only 0.050(2) A of the P(1) atom from the plane
through its Mo, C(5) and C(12) substituents. A similar
PꢁC bond length as in 3 has been found for (CO)5Cr
1
,
(h -Mes-P=CPh2) (I) (1.679(4) A) [21]. The PꢁC dis-
tances in 3 and I do not differ significantly from that in
the free phosphaalkenes [1]. For 2,4,6-Me3C6H2ꢀP=
C(Ph)(2-i-PrC6H4) [22] with a similar substitution at the
carbon and phosphorus atom of the PꢁC unit as in 3 a
,
value of 1.682(2) A was observed.
2a: Anal. Found: C, 79.93; H, 8.00. Calc. for
C37H44P2 (550.7): C, 80.69; H, 7.99%. — MS: (m/e)=
550 [M+], 494 [M+−C4H9], 474 [M+−C6H5], 305
[M+−t-Bu3C6H2]; — 1H-NMR (C6H6-d6, l): 1.30 (p-
t-Bu), 1.57 (o-t-Bu), 6.9–7.3, (arom. H), 7.63 (arom. H,
2,4,6-t-Bu3C6H2), 8.32, 9.29 (J=24.7, 5.8 Hz); —
13C{1H}-NMR (C6H6-d6, l): 174.5 (J=23.4, 13.2 Hz),
154.6, 149.9, 145.1 (J=13.2, 13.2 Hz), 139.6 (J=57.0
Hz), 137.5 (J=11.2 Hz), 135.2 (J=14.2, 14.2 Hz),
134.6, 134.3 (J=19.2 Hz), 129.5, 128.7 (J=7.1 Hz),
128.6, 128.5 (J=6.1 Hz), 126.1 (J=27.4, 4.1 Hz),
122.0, 38.4, 35.1, 34.2 (J=6.1 Hz), 31.5; — 31P{1H}-
NMR (C6H6-d6, l): 268.2 (J=20.4 Hz), −14.0 (J=
20.4 Hz).
Despite the P(1)ꢀC(5) multiple bond, the
C(5)ꢀP(1)ꢀC(12) angle is 40.6(3)° smaller than the
MoꢀP(1)ꢀC(12) angle. This asymmetry may in part be
due to the steric interactions between the Mo(CO)4
group and the bulky 2,4,6-tri-t-butylphenyl residue.
The aromatic ring of the latter forms an angle of
80.5(2)° with the substituent plane of the P(1) atom. As
is evident in Fig. 1, the six-membered chelate ring is
nonplanar, a twist boat conformation being adopted. In
accordance with the multiple bond nature of the
P(1)ꢀC(5) and C(6)ꢀC(7) linkages, the C(5)ꢀC(6)ꢀ
C(7)ꢀP(2) and MoꢀP(1)ꢀC(5)ꢀC(6) fragments of the
,
chelate ring are planar within 90.034 A. Apparently
p-conjugation between these two fragments is not dis-
rupted by the −25.2(8)° torsion along the
P(1)ꢀC(5)ꢀC(6)ꢀC(6)ꢀC(7) sequence, the C(5)ꢀC(6)
5.1.2. Irradiation of 2a
A benzene solution of 0.39 g (0.7 mmol) of 2a in 20
,
bond length of 1.443(7) A indicating a significant de-
gree of multiple bonding.
ml of benzene was irradiated for 6 h with a mercury
1
high pressure lamp with cooling. Thereafter the H-,
13C{1H}- and 31P{1H}-NMR spectra of the reaction
mixture were taken. The resonances which could be
assigned to the Z-isomer 2b are collected below.
5. Experimental
1
2b: H-NMR (C6H6-d6, l): 1.45 (p-t-Bu), 1.55 (o-t-
The starting materials were characterized by 1H-,
13C{1H}- and 31P{1H}-NMR spectroscopy and mass
Bu), 7.2–8.3 (arom. H), 7.61 (arom. H, 2,4,6-t-
Bu3C6H2), 9.25 (J=35.8, 8.9 Hz;) — 13C-NMR
(C6H6-d6, l): 159.9 (J=51.4, 31.0 Hz), 154.2, 151.0,
142.9 (J=22.9, 22.9 Hz), 137.1 (J=11.2 Hz), 137.0
(J=10.2 Hz), 136.4 (J=13.2, 13.2 Hz), 134.6, 134.0
(J=4.1 Hz), 129.9 (J=9.7, 2.5 Hz), 128.8 (J=5.1 Hz),
128.7 (J=10.2 Hz), 128.5 (J=2.0 Hz), 127.8 (J=7.1
Hz), 122.6, 38.3, 35.2, 33.0, 31.7; — 31P{1H}-NMR
1
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. The
compounds
2,4,6-t-Bu3C6H2ꢀPH2
(1b)
[11],
C7H8Mo(CO)4 [15] and 2-PPh2ꢀC6H4ꢀCHO [7b] were

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D.J. Brauer et al. / Journal of Organometallic Chemistry 626 (2001) 106–112
(C6H6-d6, l): 248.7 (J=12.7 Hz), −13.1 (J=12.7
Hz).
35.4, 35.1, 31.1; — 31P{1H}-NMR (CD2Cl2, l): 194.7
(J=24.2 Hz), 22.2 (J=24.2 Hz).
5: Anal. Found: C, 54.10; H, 5.73. Calc. for
C37H44Cl2P2Pt (816.7): C, 54.43; H, 5.43%. — 1H-
NMR (CD2Cl2, l): 1.58 (p-t-Bu), 1.37 (o-t-Bu), 6.90
(J=12.0, 7.9 Hz), 7.2–7.8 (arom. H), 7.89 (J=17.8,
2.5 Hz). — 13C-NMR (CD2Cl2, l): 155.7 (J=4.0 Hz),
154.0 (J=3.1 Hz), 142.1 (J=11.7, 5.6 Hz), 138.1 (J=
84.4, 11.2 Hz), 136.3 (J=5.6, 5.6 Hz), 134.5 (J=10.2
Hz), 133.2, 132.0 (J=2.0 Hz), 131.9 (J=28.0, 6.6 Hz),
129.6 (J=8.7, 8.7 Hz), 128.9 (J=12.2 Hz), 128.9 (J=
69.2 Hz), 124.8 (J=11.2 Hz), 121.2 (J=47.8 Hz),
115.3 (J=63.1, 19.3 Hz), 39.7, 35.5, 35.1, 31.1; —
31P{1H}-NMR (CD2Cl2, l): 169.7 (J=4195.4, 36.0
Hz), 2.1 (J=3175.9, 36.0 Hz).
5.2. Synthesis of the complexes 3–5
5.2.1. Preparation of 3
2,5-Norbornadiene-tetracarbonyl
molybdenum(0)
(0.06 g, 0.2 mmol) and 2a (0.11 g, 0.2 mmol) were
dissolved in 20 ml of benzene and the solution was
stirred at ambient temperature for 1.5 days. Thereafter
all volatiles were removed in vacuo (20°C, 0.01 mbar)
and the remaining red colored residue was recrystallized
from n-heptane. Yield: 0.09 g (60%).
3: Anal. Found: C, 65.74; H, 6.08. Calc. for
C41H44MoO4P2 (758.7): C, 64.91; H, 5.84%. — MS:
(m/e)=757 [98M+−3H]; 730 [98M+−CO−2H], 703
[98M+−2CO−H], 676 [98M+−3CO], 647 [98M+−
4CO−3H]; — 1H-NMR (C6H6-d6, l): 1.39 (p-t-Bu),
1.64 (o-t-Bu), 6.4–7.4 (arom. H); — 13C-NMR (C6H6-
d6, l): 209.4, 169.1 (J=36.1, 7.6 Hz), 156.1, 151.4,
144.1 (J=15.3 Hz), 137.9 (J=4.1 Hz), 136.0 (J=34.6,
4.1 Hz), 133.6 (J=13.2 Hz), 133.2 (J=3.1 Hz), 132.1
(J=22.4, 7.1 Hz), 130.8, 130.0, 128.7 (J=9.2 Hz),
128.7 (J=5.7, 5.7 Hz), 125.1 (J=31.0, 8.7 Hz), 122.9
(J=6.1 Hz), 39.3, 35.1, 32.0, 31.3; — 31P{1H}-NMR
(C6H6-d6, l): 256.5 (J=30.5 Hz), 34.5 (J=30.5 Hz);
IR (hexane, cm−1): 2027(s), 1942(m), 1928(s), 1920(s).
5.3. X-ray structure analysis of 3·C7H16
Crystallization of the molybdenum complex 3 proved
difficult — evaporation of solutions in a variety of
solvents leading to microcrystalline material. Crystals
suitable for X-ray structural analysis were only ob-
tained when heptane was used as the solvent. Such a
crystal was sealed in a glass capillary. X-ray measure-
ments were made with a Siemens P3 diffractometer
,
using Mo–Ka radiation (0.71073 A) and a graphite
monochromator. Intensities were extracted from the
profiles of q−2q scans, and they were corrected for the
slight shift of the three periodically monitored standard
reflections and absorption. The data were merged in
accordance with the Laue symmetry of the crystal to
give unique reflections. Direct methods revealed a large
fragment of the molybdenum complex, and its remain-
ing non-hydrogen atoms were located in a subsequent
difference Fourier map.
5.2.2. Preparation of 4 and 5
To a suspension of 0.60 g (3.4 mmol) of PdCl2 or
0.294 g (1.1 mmol) of PtCl2 in 20 ml of methanol 1.87
g (3.4 mmol) or 0.607 g (1.1 mmol) of 2a were added
with stirring at ambient temperature. The yellow pre-
cipitate that formed after 3 days was separated by
filtration through a suction funnel. In the case of 4 the
solid was washed with three aliquots of 35 ml of hot
ethanol. The residue was dried in vacuo. For the isola-
tion of 5 the yellow solid was suspended in 10 ml of
dichloromethane and filtered through a glasfritted fun-
nel. The solvent was removed from the filtrate in vacuo
and the residue was washed with 20 ml of hot ethanol.
Yields: 2.1 g (85%) 4, 0.7 g (78%) 5.
After these atoms were refined anisotropically, the
associated hydrogen atoms were entered in calculated
,
positions (CꢀH=0.95 A) and assigned isotropic tem-
perature factors. After refinement of this model (wR2=
0.177), a difference Fourier synthesis was calculated in
order to locate the heptane molecule. While the atomic
positions could not be resolved, a banana-shaped re-
gion of continuous electron density between 0.2 and 0.9
−1
,
,
For the preparation of 4 instead of PdCl2 0.23 g (0.7
mmol) of K2PdCl4 and 0.51 g (0.9 mmol) of 2a could be
used. The workup procedure is as above.
e A
was found to extent for about 8 A in a channel
lying parallel to the a-axis. Apparently the heptane
molecule is disordered, and a disorder model was con-
structed from a planar C7 chain by rotating this frag-
ment by 90, 180, and 270° about an axis that runs
through the midpoints of the six CꢀC bonds. The 28
atoms of this model were given occupancies of 0.25 and
a common isotropic temperature factor, and the atomic
assembly was refined as a rigid group. While the use of
this disorder model lowered the standard deviations of
the complex by about 20%, the coordinates of the
heptane carbon atoms cannot be taken seriously. The
planar chains seem to be extended in the channel —
4: Anal. Found: C, 61.02; H, 6.01. Calc. for
C37H44Cl2P2Pd (728.0): C, 61.04; H, 6.09%. — 1H-
NMR (CD2Cl2, l): 1.39 (p-t-Bu), 1.54 (o-t-Bu), 6.90
(J=11.2, 8.1 Hz), 7.2–7.7 (arom. H); — 13C-NMR
(CD2Cl2, l): 155.4 (J=2.0 Hz), 153.9 (J=2.0 Hz),
146.9 (J=63.1, 17.3 Hz), 141.4 (J=12.7, 4.6 Hz), 136.4
(J=4.6 Hz), 134.5 (J=11.2 Hz), 133.5, 132.6 (J=24.9,
7.6 Hz), 132.1 (J=3.1 Hz), 130.7 (J=8.7 Hz), 129.1
(J=12.2 Hz), 128.7 (J=60.0 Hz), 124.8 (J=11.2 Hz),
123.2 (J=30.5 Hz), 116.8 (J=53.4, 25.0 Hz), 39.5,

D.J. Brauer et al. / Journal of Organometallic Chemistry 626 (2001) 106–112
111
Table 1
References
Crystallographic data for 3·C7H16
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Empirical formula
Formula weight
Crystal system
Space group
C41H44MoO4P2·C7H16
858.84
Orthorhombic
P212121
16.009(3)
16.358(4)
18.163(4)
4756.3(17)
,
a (A)
,
b (A)
,
c (A)
3
,
V (A )
Z
4
Dcalc (g cm−3
T (K)
)
1.199
290(2)
q Range (°)
2.10–25.06
05h519, 05k519, −215l521
9344
8429
Limiting indices
Reflections collected
Unique
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Rint
0.0215
6263
0.31×0.29×0.24
0.382
0.9248–0.9077
0.0644
Observed (I\2|)
Crystal size (mm)
v (mm−1
)
Transmission
R1 (all data)
WR2 (all data)
Goodness-of-fit
0.1259
0.954
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Parameters
441
0.489/−0.300
−0.02(5)
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.
,
2.7 A. Crystal data are listed in Table 1. While the
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6. Supplementary material
Additional crystallographic data (excluding structure
factors) have been deposited with the Cambridge Crys-
tallographic Data Centre as supplementary publication
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free of charge on application to CCDC, 12 Union
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Acknowledgements
This work was supported by Deutsche Forschungsge-
meinschaft and Fonds der Chemischen Industrie,
Celanese GmbH and Clariant GmbH are thanked for
financial support.

112
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.