Synthesis of bimetallic phosphido-bridged isocyanide M-Mo (M = Mo, W) complexes

Article abstract of DOI:10.1021/om9802360

The reaction of CpM(CO)₂(μ-PPh₂)Mo(CO)₅ (M = Mo, W) with phosphine imide was regiospecific with the isocaynide ligand regiospecifically coordinated to the Mo atom to produce bimetallic isocyanide complexes CpM(CO)₂(μ-PPh₂)Mo(CO)₄(CNR) (M = Mo, W; R = Pr, CH₂Ph, ⁱPr). A single-crystal study of cis-CpW(CO)₂(μ-PPh₂)Mo(CO)₄(CNPr) was performed.

Full text of DOI:10.1021/om9802360

Organometallics 1998, 17, 4739-4743
4739
Syn th esis of Bim eta llic P h osp h id o-Br id ged Isocya n id e
M-Mo (M ) Mo, W) Com p lexes
Shin-Guang Shyu,* Ramsharan Singh, and Kuan-J iuh Lin
Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, Republic of China
Received March 30, 1998
The reaction of CpM(CO)2(µ-PPh2)Mo(CO)5 (M ) Mo, W) with phosphine imide was
regiospecific with the isocaynide ligand regiospecifically coordinated to the Mo atom to
produce bimetallic isocyanide complexes CpM(CO)2(µ-PPh2)Mo(CO)4(CNR) (M ) Mo, W; R
i
) Pr, CH2Ph, Pr). A single-crystal study of cis-CpW(CO)2(µ-PPh2)Mo(CO)4(CNPr) was
performed.
Phosphine imide, a deoxygenating reagent,1 has been
used to react with metal carbonyl compounds to prepare
isocyanide metal complexes.2 Nucleophilic attack of the
phosphine imide at the carbonyl carbon followed by the
elimination of the triphenylphosphine oxides to generate
the isocyanide ligand was proposed as the reaction
mechanism.2 This effective alternative preparation
method has been successfully employed on monomeric
metal complexes and homonuclear trimeric cluster
compounds.2a,b,3 However, reaction between phosphine
imide and heterobimetallic carbonyl complex has not
been revealed. Reported herein is the study of the
satellite was observed) and a broad hump. 1H NMR
showed signals of Cp and Ph protons with the Cp to Ph
intensity ratio 1:2 in all the products. The rest of the
proton signals in the spectrum indicate that there is
totally one isocyanide ligand in the products. The
observed ν(CN) stretching frequencies of the products
(2170 cm-1 for 2 to 2162 cm-1 for 7) in their IR spectra
further indicate the presence of a coordinated CN
ligand.6 In addition, elemental analysis of the products
is consistent with the empirical formula of the isocya-
regiospecific reaction between phosphine imides and
phosphido-bridged bimetallic complexes CpM(CO)2(µ-
PPh2)Mo(CO)5 (M ) Mo, W).
The bimetallic complex CpM(CO)2(µ-PPh2)Mo(CO)5
(M ) Mo, W) (1)4,5 has two sets of carbonyl ligands. One
set is composed of the carbonyl ligands on the CpM-
(CO)2 (M ) Mo, W) moiety; the other set is the carbonyl
ligands on Mo(CO)5. Complex 1 reacts with phosphine
imide to produce CpM(CO)2(µ-PPh2)Mo(CO)4(CNR) (M
) Mo, W; R ) Pr, CH2Ph, iPr) with the isocyanide ligand
coordinated to the Mo as the only isolated product.
nide complex CpM(CO)2(µ-PPh2)Mo(CO)4(CNR) (M )
Mo, W; R ) Pr, CH2Ph, Pr). All this indicates the
product is a mixture of isomers and rules out the
possibility that the product is a pure compound with
two phosphorus atoms in the complex. To clarify the
position of the isocyanide ligand and identify the
structure of the products, single-crystal X-ray diffraction
i
Reaction between CpM(CO)2(µ-PPh2)Mo(CO)5 (M )
Mo, W) (1) and phosphine imides produced maroon red
solids. 31P NMR spectra of these red solids at room
temperature showed a sharp singlet (for M ) W, J P-W
study of cis-CpW(CO)2(µ-PPh2)Mo(CO)4(CNPr) (5-cis)
obtained from the product mixture was carried out.
Figure 1 shows the ORTEP structure of the complex.
(1) Abel, E. W.; Mucklejoin, S. A. Phosphorus Sulfur Relat. Elem.
1981, 9, 235, and references therein.
(2) (a) Kiji, J .; Matsumura, A.; Haishi, T.; Okazaki, S.; Furukawa,
J . Bull. Chem. Soc. J pn. 1977, 50, 2731. (b) Alper, H.; Partis, R. A. J .
Organomet. Chem. 1972, 35, c40. (c) Mirkin, C. A.; Lu, K. L.; Geoffroy,
G. L.; Rheingold, A. L.; Staley, D. L. J . Am. Chem. Soc. 1989, 111,
7279.
(3) (a) Chen, L. C.; Chen, M. Y.; Chen. J . H.; Wen, Y. S.; Lu, K. L.
J . Organomet. Chem. 1992, 425, 99. (b) Lin. Y. W.; Gau, H. M.; Wen,
Y. S.; Lu, K. L. Organometallics 1992, 11, 1445. (c) Mirkin, C. A.; Lu,
K. L.; Snead, T. W.; Young, B. A.; Geoffroy, G. L.; Rheingold, A. L.;
Haggerty, B. S. J . Am. Chem. Soc. 1991, 113, 3800. (d) Lu, K. L.; Chen,
C. C.; Lin, Y. W.; Hong, F. E.; Gau, H. M.; Gan, L. L.; Luoh, H. D. J .
Organomet. Chem. 1993, 453, 263.
The structure of 5-cis is similar to the structure of
its parent compound CpW(CO)2(µ-PPh2)Mo(CO)5 (1-W).5
A W-Mo distance of 3.1894(8) Å, which is similar to
the W-Mo bond length of 3.2054(16) Å in 1-W, indicates
a metal-metal bond between two metals in the complex.
(4) Shyu, S.-G. Unpublished results.
(5) Shyu, S.-G.; Hsu, J .-Y.; Lin, P.-J .; Wu, W.-J .; Peng, S.-M.; Lee,
G. H.; Wen, Y.-S. Organometallics 1994, 13, 1699.
(6) Albers, M. O.; Coville, N. J .; Singleton, E. J . Organomet. Chem.
1987, 323, 37.
S0276-7333(98)00236-2 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 09/12/1998

4740 Organometallics, Vol. 17, No. 21, 1998
Shyu et al.
F igu r e 1. ORTEP drawing of 5. Hydrogen atoms are
omitted.
This observation is consistent with the observed down-
field resonance of the phosphorus signal in its 31P NMR
spectrum.7
The isocyanide ligand coordinates to the Mo and is
cis to the phosphido bridge ligand. The observed 13C
NMR tungsten carbonyl resonance signals at 229.7
(J C-P ) 17.4 Hz) and 223.8 ppm, which are in good
agreement with the W carbonyl resonance signals in
1-W (226.7 ppm, J C-P ) 17.5 Hz; 221.8 ppm) and the
W carbonyl resonance signals of its phosphine derivative
CpW(CO)2(µ-PPh2)Mo(CO)4(PPh3) (231.0 ppm, J C-P
)
15.8 Hz; 223.5 ppm), are consistent with the two
carbonyl ligands on the W atom.5
Attempts to obtain the spectroscopic data of the pure
cis isomer failed. When the crystals of the cis isomers
were dissolved in solution, the 1H and 31P NMR spectra
of the solution were the same as the product mixture
obtained in the first stage. This indicates that isomer-
ization occurs when the pure cis isomer dissolves into
the solvent.
The only observed 13C NMR tungsten carbonyl reso-
nance signals at 229.7 and 223.8 ppm indicate that the
other isomer also has two carbonyl ligands on the W
atom. This indicates that the isocyanide ligand is
coordinated to the Mo in both isomers. We propose the
other isomer to be the trans isomer. Transformations
between cis and trans isomers in heterobimetallic
phosphido-bridged complexes have been observed in
F igu r e 2. (a) Variable-temperature 31P{1H} NMR and (b)
1H NMR spectra of 5 in toluene-d8. Only the Cp region is
shown in part b. 5-cis a and 5-cis b represent two
conformational isomers of 5-cis. Signals due to impurities
are marked *.
signals. One was a broad hump at 163 ppm. The other
was a sharp singlet at 163.8 with signal to J P-W satellite
intensity ratio 11:1. At 273 K, the sharp singlet
remained unchanged; however, the hump split into two
broad signals. Below 253 K, these two signals sharp-
ened and the J P-W satellites could be observed. The
coalescence temperature was obtained at 340 K. The
broad signal sharpened (164.3 ppm), and the J P-W
(340.2 Hz) could be clearly observed.
The broad signal is assigned to the cis isomer in which
the isocyanide ligand is coordinated to Mo and cis to
the phosphido bridge. It has been proposed that the
four ligands cis to the phosphido bridge ligand are
fluxional through the rotation of the Mo-P bonding.5,8
In addition, in CpW(CO)3(µ-PPh2)Mo(CO)4(L) (L )
P(OMe)3, PPh3, PPh2H), the Mo-P bond can rotate in
the solution such that two conformational isomers are
CpFe(CO)(µ-PPh2)W(CO)4(L) (L ) P(OMe)3, PPh3,
PPh2H).8
The broad hump at 163 ppm in the 31P NMR indicates
the possibility of the fluxional behavior of one isomer.
To understand this fluxional behavior and to assign the
NMR signals in the mixture spectra, variable-temper-
ature 31P NMR of 5-cis was obtained in toluene-d8
(Figure 2a). At room temperature, there were two
(7) (a) Carty, A. J .; Maclaughlin, S. A.; Nucciarone, D. In Phos-
phrous-31 NMR Spectroscopy in Stereochemical Analysis: Organic
Compounds and Metal Complexes; Verkade, J . G., Quin, L. P., Eds.;
VCH: New York, 1987; Chapter 16, and references cited therein. (b)
Carty, A. J . Adv. Chem. Ser. 1982, No. 196, 163. (c) Garrou, P. E. Chem.
Rev. 1981, 81, 229.
(8) Shyu, S.-G.; Lin, P.-J .; Lin, K.-J .; Chang, M.-G.; Wen, Y.-S.
Organometallics 1995, 14, 2253.

Bimetallic Phosphido-Bridged Isocyanide Complexes
Organometallics, Vol. 17, No. 21, 1998 4741
Ta ble 1. Sp ectr oscop ic Da ta for th e Com p lexes
1H NMR,a,b,d 13C{1H} NMR,a,d
5.05 (s, 5H, C5H5)
complex
31P{1H} NMR,a,b
204.51
δ
δ
δ
IR,c,f cm-1
1-Mog
ν (CO), 2071 m, 1964 s, 1935 sh,
1869w
ν (CN), 2170w; ν (CO), 2036m,
2021w, 1941s, 1853w
2-cise
199.59(br)
5.01 (s, 5H, C5H5), 3.33 (t, 2H,
CNCH2, J H-H ) 6.52 Hz), 1.50
(m, 2H,-CH2-), 0.84 (t, 3H,
-CH3, J H-H ) 7.35 Hz)
4.95 (s, 5H, C5H5), 3.72 (t, 2H,
CNCH2, J H-H ) 6.42 Hz), 1.84
(m, 2H, -CH2-), 1.12 (t, 3H,
-CH3, J H-H ) 7.36 Hz)
92.93 (s, C5H5), 45.96 (s,
CNCH2), 22.50 (s,
-CH2-), 10.92 (s, CH3)
2-tr a n se 202.53
92.60 (s, C5H5), 46.72 (s,
CNCH2), 23.12
(s, -CH2-), 10.92
(s, CH3)
3-cise
200.06(br)
5.01 (s, 5H, C5H5), 4.65 (d, 1H,
CHaHb, J H-H ) 16.5 Hz), 4.55
(d, 1H, CHaHb, J H-H ) 16.8 Hz)
4.96 (s, 5H, C5H5), 4.99 (s, CH2)
155.97 (br, CN), 92.92 (s, ν (CN), 2164w; ν (CO), 2036m,
C5H5), 48.09 (s, CH2)
2021w, 1941s, 1855w
3-tr a n se 202.53
92.63 (s, C5H5), 48.65 (s,
CH2)
4-cise
198.52(br)
5.02 (s, 5H, C5H5), 3.77 (m, 1H, CH), 92.88 (s, C5H5), 48.63 (s,
1.18 (d, 3H, CHCH3, J H-H
ν (CN), 2162w; ν (CO), 2036m,
2020w, 1939s, 1854w
)
CH), 22.88 (s, -CH3)
6.60 Hz), 1.21 (d, 3H, CHCH3,
J H-H ) 6.45 Hz)
4.95 (s, 5H, C5H5), 4.11 (m, 1H, CH), 92.55 (s, C5H5), 49.32 (s,
4-tr a n se 202.47
1.20 (d, 6H, CH3, J H-H ) 6.45 Hz)
170.46 (J P-W ) 342.6) 5.17 (s, 5H, C5H5)
166.45(br) 5.13 (s, 5H, C5H5), 3.35 (t, 2H,
CH), 23.55 (s, -CH3)
1-Wg
ν (CO), 2071m, 1961s, 1929sh, 1856w
ν (CN), 2169w; ν (CO), 2037m,
2022w, 1935s, 1843m
5-cise
91.31 (s, C5H5), 45.92 (s,
CNCH2), 22.45
(s, -CH2), 10.87 (s,
-CH3)
91.01 (s, C5H5), 46.73 (s,
CNCH2), 22.97
(s, -CH2), 10.87 (s,
-CH3)
91.36 (s, C5H5), 48.05 (s,
CH2)
CNCH2, J H-H ) 6.60 Hz), 1.52
(m, 2H, -CH2-), 0.84 (t, 3H,
-CH3, J H-H ) 7.20 Hz)
5-tr a n se 169.34 (J P-W ) 329.3) 5.05 (s, 5H, C5H5), 3.69 (t, 2H,
CNCH2, J H-H ) 6.60 Hz), 1.84
(m, 2H, -CH2-), 1.12 (t, 3H,
-CH3, J H-H ) 7.50 Hz)
6-cise
167.07(br)
5.12 (s, 5H, C5H5), 4.58 (d, 1H,
CHaHb, J H-H ) 18.0 Hz), 4.68
(d, 1H, CHaHb, J H-H ) 18.0 Hz)
ν (CN), 2163w; ν (CO), 2038w,
2021w, 1940s, 1843w
6-tr a n se 170.46 (J P-W ) 326.8) 5.06 (s, 5H, C5H5)
91.09 (s, C5H5), 48.68 (s,
CH2)
7-cise
164.68(br)
5.12 (s, 5H, C5H5), 3.78 (m, 1H, CH), 91.31 (s, C5H5), 48.65 (s,
1.18 (d, 3H, CHCH3, J H-H
6.60 Hz), 1.21 (d, 3H, CHCH3,
ν (CN), 2162w; ν (CO), 2037w,
2021w, 1939s, 1843w
)
CH), 22.92 (s, -CH3)
J H-H ) 6.8 Hz)
7-tr a n se 169.42 (J P-W ) 326.8) 5.05 (s, 5H, C5H5), 4.02 (m, 1H, CH), 91.00 (s, C5H5), 49.37
1.50 (d, 6H, CH3, J H-H ) 6.6 Hz)
(s, CH), 23.47 (s, -CH3)
a
b
At room temperature. J values in Hz. c In CH2Cl2 solution unless otherwise indicated. Abbreviations: w, weak; m, medium; s, strong;
d
i
vs, very strong. In CDCl3 solution unless otherwise indicated. C5H5, Pr, Pr, CH2Ph, and CN group only. Abbreviations: s, singlet; d,
doublet; t, triplet; br, broad. e Not separated pure. f For complexes 5, 6, and 7 the IR of the mixture of their trans and cis isomers. These
g
data are taken from refs 4 and 5.
observed in the solution.5 On the basis of these obser-
vations, the variable 31P NMR can be explained as
follows. At low temperature there exist two conforma-
tional isomers for the cis complex. In both isomers, the
isocyanide ligands are cis to the phosphido bridge. At
higher temperature, these two conformational isomers
exchange through the rotation of the Mo-P bonding so
that the phosphido bridge signal broadens. At higher
temperature, the coalescence point is obtained and a
sharp signal is observed. For the trans isomer, the
rotation of the Mo-P bond does not result in any
structural changes. A sharp phosphido signal in 31P
NMR should remain the same throughout the temper-
ature change, as observed in the variable-temperature
NMR study.
temperature still cannot be observed because it overlaps
with the signal of one of the conformational isomers.
The attack of phosphine imide on the binuclear
complex is regiospecific. However, whether the attack
of phosphine imide on the Mo carbonyl is stereospecific
cannot be clarified. Although isomerization from the
cis isomer to the trans isomer is observed by dissolving
the single crystals of the cis isomer in solution, the
possibility of initial nucleophilic attack on the trans Mo
carbonyl still cannot be ruled out completely.
From the electronic point of view, the carbon atoms
on the cis carbonyl ligands are more electrophilic than
the carbon on the trans carbonyl ligand. First, if we
consider the metallophosphine CpM(CO)2PPh2 (M ) Mo,
W) as a ligand similar to a phosphine ligand, the
aptitude of back-donation from the Mo to the trans
carbonyl ligand should be larger than that to the cis CO
ligand because phosphine is a better electron donor than
carbonyl. This makes the carbon atom on the trans CO
ligand less electophilic than the carbon atoms on the
1
The cis and trans isomers can also be observed in H
NMR. Both isomers have different Cp and different
isocyanide proton resonance positions and can be as-
signed easily (Table 1). However, at 273-253 K, the
Cp protons of both stereoisomers have similar resonance
1
position in the H NMR and cannot be resolved (Figure
2b). At 233 K, signals corresponding to the conforma-
tional isomers of the cis isomer can be observed at 4.65
and 4.61 ppm. The signal of the trans isomer at that
cis CO ligands. Second, in CpM(CO)2(µ-PPh2)Mo(CO)5
(M ) Mo, W), the metal-metal bond can be considered
as a dative bonding from Mo to M. The Mo metal

4742 Organometallics, Vol. 17, No. 21, 1998
Shyu et al.
Ta ble 2. Cr ysta l a n d In ten sity Collection Da ta for
5-cis
donates two electrons from its filled t2g orbitals to the
adjacent metal M.5,8 Powell suggested that the net
results of this donation will be a decrease in dxy f π
CO bonding to the equatorial CO’s.9 This may weaken
the Mo-CO bonds of the two equatorial Mo-CO’s cis to
the phosphido ligand10 and also reduces the electron
density of the carbon atom on these CO ligands. The
former will enhance the substitution of the carbonyl
ligands toward Lewis bases, as observed in the re-
mol formula
mol wt
C27H22MoNO6PW
767.24
space group
a (Å)
b (Å)
P1h
10.542(3)
10.594(4)
14.61(2)
76.76(2)
73.15(2)
62.40(3)
1375.4(7)
1.853
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
giospecific substitution reaction of CpM(CO)2(µ-PPh2)-
F(calcd) (Mg m-3
Z
)
Mo(CO)5 (M ) Mo, W) with phosphines.5 The latter
may further increase the electrophilic abilities of the
carbon atoms on the equatorial CO’s cis to the phosphido
ligand toward nucleophilic reagents, as observed in this
study.
2
cryst dimens (mm)
temp
0.19 × 0.22 × 0.31
room temperature
0.710 73
50
ω-2θ
4823
3935 (>2.0σ(I))
334
0.027
λ(Μï ΚR) (Å)
2θ range (deg)
scan type
no. of reflns
no. of obsd rflns
variables
R
Exp er im en ta l Section
All reactions were carried out under a purified nitrogen
atmosphere with standard Schlenk techniques. Infrared (IR)
spectra were recorded on a Perkin-Elmer 882 infrared spec-
trophotometer. The 1H, 13C, and 31P NMR spectra were
recorded by using Bruker AMX-500, MSL-200, AC-200, and
AC-300 spectrometers. The 31P NMR shifts are referenced to
85% H3PO4. Except as noted, spectra were collected at room
temperature. The fast atom bombardment (FAB) mass spectra
were recorded on a VG70-250S or a J EOL J MS-HX 110 mass
spectrometer. Microanalyses were performed by the Mi-
croanalytical Laboratory at National Cheng Kung University,
Tainan, Taiwan.
Rw
S
0.029
1.38
0.840, -0.980
∆Fmax,min (e/Å3)
Ta ble 3. Selected Bon d Len gth s a n d Bon d An gles
in Com p lex 5-cis
selected
selected
bond angle (deg)
bond distance (Å)
W-Mo
W-P
W-C5
W-C6
Mo-P
3.1894(8)
2.3689(17)
1.951(6)
1.945(7)
2.5035(15)
2.052(6)
2.020(6)
2.022(6)
2.010(6)
2.120(6)
1.132(7)
1.142(7)
1.144(8)
1.127(8)
1.150(8)
1.160(8)
1.139(7)
1.454(8)
W-P-Mo
81.72(5)
82.22(18)
109.13(16)
90.06(16)
113.44(17)
89.94(17)
161.79(18)
79.87(15)
177.2(5)
176.5(5)
178.7(5)
169.7(5)
176.6(7)
P-W-C5
P-W-C6
P-Mo-C1
P-Mo-C2
P-Mo-C3
P-Mo-C4
P-Mo-C7
W-C5-O5
W-C6-O6
Mo-C1-O1
Mo-C2-O2
Mo-C3-O3
Mo-C4-O4
Mo-C7-N
C7-N-C8
Ma ter ia ls. THF was distilled from potassium and ben-
zophenone under an atmosphere of purified nitrogen just
before use. Other solvents were purified according to estab-
Mo-C1
Mo-C2
Mo-C3
Mo-C4
Mo-C7
C1-O1
C2-O2
C3-O3
C4-O4
C5-O5
C6-O6
C7-N
lished procedures.11 The complexes CpMo(CO)2(µPPh2)Mo-
4
(CO)5 (1-Mo) and CpW(CO)2(µ-PPh2)Mo(CO)55 (1-W) were
prepared according to literature procedures. The compounds
i
Ph3PdN-R (R ) Pr, CH2Ph, Pr) were prepared as described
in the literature.12,13
179.0(6)
176.9(5)
173.3(6)
Syn th esis of Cp Mo(CO)2(µ-P P h 2)Mo(CO)4(CNP r ) (2-cis
a n d 2-tr a n s). A mixture of 1-Mo (0.319 g, 0.50 mM) and
Ph3PdN-Pr (0.319 g, 1.00 mM) in 20 mL of THF was stirred
and heated at 68 °C for about 6 h. The solvent was then
removed, and the residue was chromatographed on grade III
alumina and eluted with a mixture of CH2Cl2/hexanes to afford
two fractions. From the first band, a trace amount of the
unreacted starting material was recovered on elution with 10%
CH2Cl2/hexane. The second band contained a mixture of 2-cis
and 2-tr a n s on elution with a 20% CH2Cl2/hexane mixture.
Yield: 0.260 g (76.5%). Anal. Calcd for C27H22Mo2NO6P: C,
47.74; H, 3.26; N, 2.06. Found: C, 47.84; H, 3.30; N, 2.11.
MS (FAB): M+ m/ z 680. Spectral data are given in Table 1.
C8-N
m/ z 730. Spectroscopic data indicate that the product is a
mixture of two isomers. Spectral data are given in Table 1.
Syn th esis of Cp Mo(CO)2(µ-P P h 2)Mo(CO)4(CNiP r ) (4-cis
a n d 4-tr a n s). Reaction and separation conditions similar to
those for 2 were applied to prepare 4. The reaction time was
187 h, and 0.336 g (0.53 mM) of 1-Mo and 0.336 g (1.06 mM)
of Ph3PdNiPr were used. The parent complex 1-Mo was
recovered in 0.092 g. Yield: 0.076 g (21.3% based on parent
compound used and 29.2% based on the parent compound
consumed in the reaction). Anal. Calcd for C27H22Mo2NO6P:
C, 47.74; H, 3.26; N, 2.06. Found: C, 47.41; H, 3.30; N, 2.04.
MS (FAB): M+ m/ z 681. Spectroscopic data indicate that the
product is a mixture of two isomers. Spectral data are given
in Table 1.
Syn th esis of Cp Mo(CO)2(µ-P P h 2)Mo(CO)4(CNCH2P h )
(3-cis a n d 3-tr a n s). Reaction and separation conditions
similar to those for 2 were applied to prepare 3. The reaction
time was 55 h, and 0.240 g (0.38 mM) of 1-Mo and 0.276 g
(0.75 mM) of Ph3PdN-CH2Ph were used. Yield: 0.074 g
(26.8%). Anal. Calcd for C31H22Mo2NO6P: C, 51.19; H, 3.05;
N, 1.93. Found: C, 51.62; H, 3.38; N, 1.83. MS (FAB): M+
Syn th esis of Cp W(CO)2(µ-P P h 2)Mo(CO)4(CNP r ) (5-cis
a n d 5-tr a n s). Reaction and separation conditions similar to
those for 2 were applied to prepare 5. The reaction time was
11 h, and 0.331 g (0.46 mM) of 1-W and 0.324 g (1.02 mM) of
Ph3PdN-Pr were used. Yield: 0.172 g (49.1%). Anal. Calcd
for C27H22MoNO6PW: C, 42.27; H, 2.89; N, 1.83. Found: C,
42.10; H, 2.89; N, 1.87. MS (FAB): M+ m/ z 769. Spectroscopic
data indicate that the product is a mixture of two isomers.
Spectral data are given in Table 1.
(9) Powell, J .; Coutoure, C.; Gregg, M. R. J . Chem. Soc., Chem.
Commun. 1988, 1208.
(10) The other two equatorial ligands are the phosphido ligand and
its trans CO.
(11) Perrin, D. D.; Armarego, W. L. F.; Perrin, D. R. Purification of
Laboratory Chemicals; Pergamon: Oxford, U.K.
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(13) Staudinger, H.; Meyer, J . Helv. Chim. Acta 1919, 2, 635.

Bimetallic Phosphido-Bridged Isocyanide Complexes
Organometallics, Vol. 17, No. 21, 1998 4743
ite-monochromated Mo KR radiation. The structure was
solved by direct methods and refined by full-matrix least-
squares using SHELXL-93. All non-hydrogen atoms were
refined with anisotropic displacement parameters, and all
hydrogen atoms were constrained to geometrically calculated
positions.
Syn th esis of Cp W(CO)2(µ-P P h 2)Mo(CO)4(CNCH2P h ) (6-
cis a n d 6-tr a n s). Reaction and separation conditions similar
to those for 2 were applied to prepare 6. The reaction time
was 48 h, and 0.340 g (0.47 mM) of 1-W and 0.349 g (0.95 mM)
of Ph3PdN-CH2Ph were used. Yield: 0.092 g (24.0%). Anal.
Calcd for
C31H22MoNO6PW: C, 45.67; H, 2.72; N, 1.72.
Found: C, 45.41; H, 3.06; N, 1.56. MS (FAB): M+ m/ z 818.
Spectroscopic data indicate that the product is a mixture of
two isomers. Spectral data are given in Table 1.
Crystal data and details of data collection and structure
analysis are summarized in Table 2. Selected interatomic
distances and bond angles are given in Tables 3. The final
positional and displacement parameters for all atoms are
provided in the Supporting Information.
Syn th esis of Cp W(CO)2(µ-P P h 2)Mo(CO)4(CNiP r ) (7-cis
a n d 7-tr a n s). Reaction and separation conditions similar to
those for 2 were applied to prepare 7. The reaction time was
72 h, and 0.319 g (0.44 mM) of 1-W and 0.280 g (0.88 mM) of
Ph3PdN-iPr were used. Yield: 0.122 g (36%). Anal. Calcd
for C27H22MoNO6PW: C, 42.27; H, 2.89; N, 1.83. Found: C,
42.07; H, 3.08; N, 1.85. MS (FAB): M+ m/ z 768. Spectroscopic
data indicate that the product is a mixture of two isomers.
Spectral data are given in Table 1.
Ack n ow led gm en t. We wish to thank Dr. K. L. Lu
for his generous supply of phosphine imides and the
National Science Council, Republic of China, and Aca-
demia Sinica for financial support of this work.
Su p p or tin g In for m a tion Ava ila ble: Listings of calcu-
lated atomic coordinates, anisotropic thermal parameters, and
bond distances and angles of compound 5-cis (7 pages).
Ordering information is given on any current masthead page.
Str u ctu r e Deter m in a tion of cis-Cp W(CO)2(µ-P P h 2)Mo-
(CO)4(CNP r ). A crystal of 5-cis was grown by slow diffusion
of hexanes into the saturated CH2Cl2 solution of the mixture
of 5-cis and 5-tr a n s at 4 °C. Diffraction measurements were
made using an Enraf-Nonius CAD4 diffractometer with graph-
OM9802360