Metal-metal-bond-assisted substitution reaction of a heterobimetallic phosphido-bridged Mo-Fe complex

Article abstract of DOI:10.1021/om970786i

The heterobimetallic phosphido-bridged complexes CpMo(CO)₂(M-PPh₂)Fe(CO)₄ (1) and CpMo(CO)₃(μ-PPh₂)Fe(CO)₄ (2) were prepared by the reaction of CpMo(CO)₃PPh₂ with Fe₂(CO)₉. The reaction between 1 and Lewis bases L(L = P(OMe)₃, PPh₂H, PPh₃) at ambient temperatures produced CpMo(CO)₂(μ-PPh₂)Fe(CO)₃(L) (3) with L regiospecifically coordinated to Fe. However, 2 did not react with L under similar conditions.

Full text of DOI:10.1021/om970786i

Organometallics 1998, 17, 1151-1154
1151
Meta l-Meta l-Bon d -Assisted Su bstitu tion Rea ction of a
Heter obim eta llic P h osp h id o-Br id ged Mo-F e Com p lex
Shu-Min Hsiao†,‡ and Shin-Guang Shyu*,†
Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, Republic of China, and
Department of Material and Mineral Resources Engineering, National Taipei University of
Technology, Taipei, Taiwan, Republic of China
Received September 8, 1997
The heterobimetallic phosphido-bridged complexes CpMo(CO)2(µ-PPh2)Fe(CO)4 (1) and
CpMo(CO)3(µ-PPh2)Fe(CO)4 (2) were prepared by the reaction of CpMo(CO)3PPh2 with Fe2-
(CO)9. The reaction between 1 and Lewis bases L (L ) P(OMe)3, PPh2H, PPh3) at ambient
temperatures produced CpMo(CO)2(µ-PPh2)Fe(CO)3(L) (3) with L regiospecifically coordinated
to Fe. However, 2 did not react with L under similar conditions.
An interesting cooperativity effect between metals in
bimetallic phosphido-bridged complexes is that a metal
can activate the substitution reaction of its adjacent
metal carbonyl through the formation of a metal-metal
bond.1,2 The metal-metal bond was proposed to influ-
ence the reactivity of the bimetallic complex in two
ways. One way is the electron donation from one metal
to its adjacent metal through the metal-metal bond.1
The second way is that the metal-metal bond can bring
two metals together. The metal carbonyl is thus
activated by its adjacent metal to form a semibridging
carbonyl through the donation of the electron from this
electron-rich adjacent metal atom to the π* orbital of
the metal CO to form a semibridging carbonyl.1 To date,
all the reported bimetallic phosphido-bridged complexes
which show metal carbonyl substitution enhancement
all have semibridging carbonyl ligands which are pri-
marily coordinated to the metals where substitution
criterion for substitution enhancement in bimetallic
complexes is still interesting in the understanding of
this kind of cooperativity effect.
To investigate whether a semibridging carbonyl ligand
is a necessary structural criterion in bimetallic carbonyl
substitution enhancement, we studied the substitution
reaction of CpMo(CO)2(µ-PPh2)Fe(CO)4 (1).4 First, this
complex is similar in molecular construction to previ-
ously reported bimetallic phosphido-bridged systems:
CpW(CO)2(µ-PPh2)W(CO)5,1d CpFe(CO)(µ-CO)(µ-PPh2)-
W(CO)4,1a CpW(CO)2(µ-PPh2)Mo(CO)5,3c and CpW(CO)2-
(µ-CO)(µ-PPh2)Fe(CO)3.2b,4 Enhancement of the substi-
tution of the Fe carbonyl in this complex can be
expected. Second, its non-metal-metal-bonded ana-
logue CpMo(CO)3(µ-PPh2)Fe(CO)4 (2) can be prepared
and serves as a standard for the comparison of their
reactivities to reveal the influence of the metal-metal
occurs.1,3 However, in the (CO)4Ru(µ-PPh2)Co(CO)3
system, substitution of the Co carbonyl by Lewis base
was proposed to be enhanced by the metal-metal
bond.2a In that complex, no semibridging carbonyl
ligand was present. Since its non-metal-metal-bonded
analogue had not been reported, a reactivity comparison
between metal-metal-bonded and non-metal-metal-
bonded complexes could not be made and substitution
enhancement by the metal-metal bond could not be
concluded without reservation. However, whether a
semibridging carbonyl ligand is a necessary structural
bond in CpMo(CO)2(µ-PPh2)Fe(CO)4. Third, and most
important, the structure of this complex has been
reported, which shows that it has no semibridging or
bridging carbonyl ligand.4
CpMo(CO)2(µ-PPh2)Fe(CO)4 (1) and CpMo(CO)3(µ-
PPh2)Fe(CO)4 (2) were prepared by the reaction between
5
CpMo(CO)3PPh2 and Fe2(CO)9 with 2 as a major
product.6,7 Because photolysis and thermolysis of 2 can
produce 1, complex 1 obtained in the reaction may result
from the further loss of a CO ligand from 2 due to the
laboratory fluorescent light.
† Academia Sinica.
‡ National Taipei University of Technology.
The structure of 2 was characterized by a single-
crystal X-ray diffraction study. Four CO ligands and
CpMo(CO)3PPh2 coordinate to the Fe0 atom to form a
(1) (a) Shyu, S.-G.; Lin, P.-J .; Lin, K.-J .; Wen, Y.-S.; Chang, M.-C.
Organometallics 1995, 14, 2253. (b) Shyu, S.-G.; Hsiao, S. M.; Lin, K.-
J .; Gau, H.-M. Organometallics 1995, 14, 4300. (c) 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. (d) Shyu, S.-G.; Wu, W.-J .; Peng, S.-
M.; Lee, G.-H.; Wen, Y.-S. J . Organomet. Chem. 1995, 489, 113.
(2) (a) Regragui, R.; Dixneuf, P. H.; Taylor, N. J .; Carty, A. J .
Organometallics 1986, 5, 1. (b) Mercer, W. C.; Whittle, R. R.;
Burkhardt, E. W.; Geoffroy, G. L. Organometallics 1985, 4, 68. (c)
Powell, J .; Sawyer, J . F.; Stainer, M. V. R. Inorg. Chem. 1989, 28, 4461.
(d) Powell, J .; Coutoure, C.; Gregg, M. R. J . Chem. Soc., Chem.
Commun. 1988, 1208.
(4) Linder, E.; Stangle, M.; Fawzi, R.; Hiller, W. Chem. Ber. 1988,
121, 1421.
(5) Malisch, W.; Maisch, R.; Colquhoun, I. J .; Mcfarlane, W. J .
Organomet. Chem. 1981, 220, C1.
(6) Adams, H.; Bailey, N. A.; Day, A. N.; Morris, M. J .; Harrison,
M. M. J . Organomet. Chem. 1991, 407, 247.
(7) (a) Braustein, P.; de J esus, E. J . Organomet. Chem. 1989, 365,
C-19. (b) Braustein, P.; de J esus, E.; Didieu, A.; Lanfranchi, M.;
Tiripicchio, A. Inorg. Chem. 1992, 31, 399.
(3) Shyu, S. G.; Lin, P.-J .; Dong, T.-Y.; Wen, Y.-S. J . Organomet.
Chem. 1993, 460, 229.
S0276-7333(97)00786-3 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 02/28/1998

1152 Organometallics, Vol. 17, No. 6, 1998
Hsiao and Shyu
F igu r e 2. 2. ORTEP drawing of 3a . Hydrogen atoms are
omitted.
F igu r e 1. ORTEP drawing of 2. Hydrogen atoms are
omitted.
Sch em e 1
distorted trigonal bipyramid (Figure 1). A Mo-Fe
distance of 4.246(6) Å is consistent with the observed
upfield resonance of the phosphido bridge signal in its
31P NMR, which indicates the absence of a metal-metal
bond.8
Photolysis or thermolysis of 2 removes one CO from
the Mo atom to form 1. The Fe-Mo bond is formed such
that both metals fulfill the 18-electron rule. The
structure of complex 1 has been reported.4 Interest-
ingly, unlike its W analogue, which has a semibridging
carbonyl ligand,1b no bridging carbonyl ligand is ob-
served in its structure.
Similar to the reaction between CpW(CO)2(µ-CO)(µ-
PPh2)Fe(CO)3 (1-w ) and Lewis bases L (L ) P(OMe)3,
PPh2H, PPh3), reaction of 1 with Lewis bases L in THF
at ambient temperature yielded 3 with L regiospecifi-
cally coordinated to Fe (Scheme 1).1b The structure of
L was stirred for 1 day. In 1, substitution of the Fe
carbonyl was completed overnight at room temperature.
Complexes 1 and 2 have similar frameworks, except
that 1 has a metal-metal bond and 2 does not. These
observations clearly indicate that CO ligands on Fe in
1 are labilized by the metal-metal bond. In 1, no
semibridging or bridging carbonyl ligand was observed
in its solid-state structure. In addition, variable-tem-
perature 13C NMR of 13CO-enriched 1 in d8-toluene did
not show any evidence of semibridging carbonyl ligands
or exchange of carbonyl ligands between metals in the
solution from 200 K to 340 K. Therefore, complexes 1
and 2 provide a definite example that a semibridging
or bridging carbonyl ligand between metals in binuclear
phosphido complexes is not an essential factor in the
activation of the metal carbonyl ligands by its adjacent
metal.
CpMo(CO)2(µ-PPh2)Fe(CO)3P(OMe)3 (3a ) was deter-
mined by a single-crystal X-ray diffraction study. The
P(OMe)3 ligand in 3a is coordinated to the Fe atom with
an Mo-Fe-P(2) angle of 172.55(3)° (Figure 2). The
Mo-Fe distance of 2.9295(5) Å, indicative of a Mo-Fe
bond, is consistent with the observed downfield reso-
nance of the phosphido bridge signal in its 31P NMR.
Complex 2 did not react with L at room temperature;
however, heating 2 with L in THF at refluxing temper-
ature produced 3. The reaction probably proceeded
through the formation of 1, which further reacted with
L to produce 3. Interestingly, 2-w did not react with L
even at reflux temperature overnight. This is under-
standable, because 2-w does not lose CO to form 1-w
under this reaction condition.
Carbonyl ligands on Fe in 2 were inert toward L (L
) P(OMe)3, PPh2H, PPh3) when a THF solution of 2 and
The Fe CO’s in 1 are probably activated by the
electron donation from Fe to its adjacent Mo through
the metal-metal bond. The net result will be a decrease
in d(Fe) f π*(CO) bonding of the Fe CO’s, as indicated
by a increase of stretching frequencies of the carbonyl
groups on Fe from 2046 (m), 1966 (s), 1957 (s) cm-1 in
(8) (a) Carty, A. J.; Maclaughlin, S. A.; Nucciarone, D. In Phosphorus-
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 therein. (b) Carty, A. J . Adv.
Chem. Ser. 1982, No. 196, 163. (c) Garrou, P. E. Chem. Rev. 1981, 81,
229.

A Phosphido-Bridged Mo-Fe Complex
Ta ble 1. Sp ectr oscop ic Da ta for 1, 2, a n d 3a
31P{1H} NMR,b,c 1H NMR,b,d
5.16 (s, 5H)
Organometallics, Vol. 17, No. 6, 1998 1153
complex
δ
δ
IR ν(CO),e cm-1
2072 m, 2017 m, 1997 s, 1989 s, 1943 s, 1877 mf
2046 m, 2029 s, 1966 s, 1957 s, 1943 m, 1910 mf
2034 m, 1961 s, 1919 s, 1845 s
1
157.7
26.0
2
3a
5.41 (s, 5H)
2
161.4 (d, J P-P 21.9, µ-PPh2), 173.6 (d,
5.04 (s, 5H), 3.62 (d,
3J P-H 12.0, 9H)
4.77 (s, 5H)
P(OMe)3)
2
3b
167.3 (d, J P-P 19.4, µ-PPh2),
2024 s, 1956 s, 1913 s, 1841 w
41.22 (d, J P-H 364.0, PPh2H)
2
3c
161.6 (d, J P-P 12.4, µ-PPh2), 63.3 (d, PPh3)
4.78 (s, 5H)
2000 w, 1950 s, 1922 s, 1850 m
a
b
d
At room temperature. J values in Hz. c In THF solution unless otherwise indicated. In CDCl3 solution unless otherwise indicated:
Cp, Me, and H groups only. Abbreviations: s, singlet; d, doublet. e In THF solution unless otherwise indicated. Abbreviations: vs, very
strong; s, strong; m, medium; w, weak; br, broad; sh, shoulder. f In hexane solution.
2 to 2072 (m), 2017 (m), 1998 (s), 1943 (s) cm-1 in 1.9
Ma ter ia ls. THF was distilled from potassium and ben-
zophenone under an atmosphere of N2 immediately before use.
Metal carbonyls (Mo(CO)6, Fe2(CO)9), PPh2Cl, PPh2H, and
This induces weakening of the Fe-CO bond in 1. The
adjacent metal therefore can be considered as an
PPh3 were obtained from Strem, P(OMe)3 was purchased from
electron sink which can receive or withdraw electrons
Merck, and 13CO (99 atom % 13C) was obtained from Isotec.
from the adjacent metal through the formation of the
Other reagents and solvents were obtained from various
metal-metal bond.
commercial sources and used as received. Na[CpMo(CO)3]12
and MoCp(CO)3PPh25 were prepared by literature procedures.
This electron redistribution increases the electron
density of the electron-receiving metal, which may
further labilize the adjacent carbonyl group through the
donation of an electron to the π* orbital of the adjacent
Fe-CO to form the semibridging carbonyl ligand10 as
in 1-w and other systems reported.1b,c,3 The amplitude
of enhancement should increase as the degree of bridg-
ing increases. This is demonstrated by the fact that
Syn th esis of Cp Mo(CO)2(µ-P P h 2)F e(CO)4 (1) a n d Cp -
Mo(CO)3(µ-P P h 2)F e(CO)4 (2). A yellow solution of Na-
[CpMo(CO)3] (4.20 g, 15.56 mmol) in 150 mL of THF was cooled
to 0 °C. PPh2Cl (2.82 mL, 15.56 mmol) was then added slowly
into the above solution. After 1 h, the solution turned dark
red. Fe2(CO)9 (5.66 g, 15.56 mmol) was then added into the
above solution. After the solution was stirred overnight, the
solvent was removed and the residue was chromatographed
on grade I Al2O3. Elution with CH2Cl2/hexane (1:6) afforded
two fractions. The red solid 1 was obtained from the first band,
which was dark red. It was identified as CpMo(CO)2(µ-PPh2)-
Fe(CO)4. Yield: 1.85 g (32.34%). A trace amount of light
brown solid was obtained from the second band and was not
characterized. The orange solid 2 was obtained from the third
band after the solvent was removed. Yield: 2.50 g (41.67%).
Anal. Calcd for C24H15FeO7PMo: C, 48.01; H, 2.52. Found:
C, 47.60; H, 2.55. MS(FAB): [M - CO]+, m/z 572.
CpFe(CO)(µ-CO)(µ-PPh2)W(CO)4 reacts at a much lower
temperature than CpW(CO)2(µ-PPh2)W(CO)5 because
the former has a higher degree of semibridging
carbonyl.1a,d However, even though both complexes 1-w
and Cp2Nb(µ-CO)(µ-PPh2)Fe(CO)3 (4) have semibridging
carbonyl ligands, the carbonyl ligand on Fe in 4 is
substituted by phosphine at a much higher temperature
(reluxing toluene) than for 1-w (room temperature).11
For 1, which has a structure framework similar to that
of 1-w but with a bridging or semibridging carbonyl
ligand, substitution of the Fe carbonyl by phosphine
proceeds under mild conditions. These observations
indicate that the activating metal moiety or the metal-
metal bond should also be considered.
P h otolysis Rea ction of 2. A red solution of 2 (0.24 g, 0.40
mmol) in 30 mL of THF in
a Pyrex Schlenk tube was
photolyzed with a Hanovia UV lamp for 1.5 h. After the
solvent was removed, the residue was chromatographed on
grade I Al2O3 and eluted with CH2Cl2/hexane (1:4). After this
solvent was removed, 1 was obtained from the first band.
Yield: 0.16 g, 70%. A trace amount of red solid was obtained
from the second band and was not identified.
Th er m olysis of 2. A red solution of 2 (0.14 g, 0.23 mmol)
in 30 mL of THF was heated to reflux for 16 h. After the
solvent was removed, the residue was chromatographed on
grade I Al2O3 and eluted with CH2Cl2/hexane (1:4). After this
solvent was removed, 1 was obtained from the first band.
Yield: 85 mg, 64.7%. A trace amount of red solid was obtained
from the second band and was not identified.
Exp er im en ta l Section
All reactions and manipulations of air-sensitive compounds
were carried out at ambient temperatures under an atmo-
sphere of purified N2 with standard procedures. Infrared (IR)
spectra were recorded on a Perkin-Elmer 882 infrared spec-
trophotometer. 1H, 13C, and 31P NMR spectra were measured
by using Bruker AC-200 and AC-300 spectrometers. 31P NMR
shifts are referenced to 85% H3PO4. Electron impact (EI) and
fast-atom bombardment (FAB) mass spectra were recorded on
a VG 70-250S or a J EOL J MS-HX 110 mass spectrometer.
Microanalyses were performed in the Microanalytic Laboratory
at National Cheng Kung University, Tainan, Taiwan, and at
Academia Sinica. Spectroscopic data (31P and 1H NMR and
IR) of all new complexes are listed in Table 1.
Syn th esis of Cp Mo(CO)2(µ-P P h 2)F e(CO)3(P R3) (R )
OMe (3a ), P h (3c); P R3P P h 2H (3c)). To a red solution of 1
(0.21 g, 0.36 mmol) in 40 mL of THF was added 44 µL of
P(OMe)3 (0.36 mmol) under N2 at ambient temperatures. After
the mixture was stirred overnight, the solvent was removed.
The residue was chromatographed on grade I Al2O3 and eluted
with CH2Cl2/hexane (1:4) to afford a red band. After this
solvent was removed, 3a was obtained as a red solid. Yield:
0.17 g (67%). Anal. Calcd for C25H24FeO8P2Mo: C, 45.07; H,
3.63. Found: C, 44.87; H, 3.64. MS (FAB): M+, m/z 667.9.
(9) The assignments of Fe carbonyl stretching frequencies and the
remaining Mo carbonyl stretching frequencies in 1 and 2 are based on
their favorable comparison to the Fe carbonyl frequencies of PPh3Fe-
(CO)4 (2055, 1978, 1943 cm-1), CpMo(CO)3 (1993 s, 1925 vs, br cm-1),
and CpMo(CO)2PMe3 (1927 s, 1864 vs, br cm-1). Clifford, A. G.;
Mukherjee, A. K. Inorg. Chem. 1963, 2, 141. See also ref 5.
(10) Cotton, F. A. Prog. Inorg. Chem. 1976, 21, 1.
Reaction conditions similar to those for 3a were applied to
prepare 3b and 3c. Complex 3b: yield 0.15 g (84%). Anal.
Calcd for C34H26FeO5P2Mo: C, 55.89; H, 3.59. Found: C,
55.45; H, 3.75. MS (FAB): M+, m/z 728. Complex 3c: yield
(11) Oudet, P.; Kubicki, M. M.; Moise, C. Organometallics 1994, 13,
4278.
(12) Bender, R.; Braunstein, P.; J ud, J .-M.; Dusausoy, Y. Inorg.
Chem. 1983, 22, 3394.

1154 Organometallics, Vol. 17, No. 6, 1998
Hsiao and Shyu
Ta ble 2. Cr ysta l a n d In ten sity Collection Da ta for
2 a n d 3a
Ta ble 3. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) in 2 a n d 3a
2
3a
complex 2
complex 3a
mol formula
mol wt
space group
a (Å)
b (Å)
c (Å)
C
24H15FeMoO7P
C25H24FeMoO8P2
667.9
P21
10.8113(8)
11.525(2)
10.9303(7)
90
97.243(6)
90
1351.0(2)
1.687
2
0.38 × 0.19 × 0.34
room temp
0.710 69
50
Selected Bond Lengths
598.12
Pca21
16.621(3)
9.048(2)
15.941(3)
90
Mo‚‚‚Fe
4.246(6)
Mo-Fe
2.9295(5)
Mo-P(1)
Mo-C(1)
Mo-C(2)
Mo-C(3)
Fe-P(1)
2.635(3)
1.978(10)
2.006(13)
2.015(9)
2.327(3)
1.72(2)
1.801(10)
1.745(11)
1.82(2)
1.149(11)
1.13(2)
1.117(10)
1.21(2)
Mo-P(1)
Mo-C(4)
Mo-C(5)
Fe-P(1)
Fe-P(2)
Fe-C(1)
Fe-C(2)
Fe-C(3)
C(1)-O(1)
C(2)-O(2)
C(3)-O(3)
C(4)-O(4)
C(5)-O(5)
2.3824(9)
1.953(4)
1.949(4)
2.2638(11)
2.1519(9)
1.789(4)
1.793(4)
1.784(4)
1.142(5)
1.137(5)
1.143(5)
1.146(6)
1.155(5)
R (deg)
â (deg)
γ (deg)
V (Å3)
90
90
Fe-C(4)
Fe-C(5)
Fe-C(6)
Fe-C(7)
C(1)-O(1)
C(2)-O(2)
C(3)-O(3)
C(4)-O(4)
C(5)-O(5)
C(6)-O(6)
C(7)-O(7)
2397.3(8)
1.657
4
0.36 × 0.32 × 0.30
room temp
0.710 69
45
ω-2θ
1639
1366 (>2.0σ(I))
307
F(calcd) (Mg m-3
Z
)
cryst dimens (mm)
temp
λ(Mo KR) (Å)
2θ range (deg)
scan type
no. of unique rflns
no. of observed rflns
variables
1.114(12)
1.138(14)
1.14(2)
ω-2θ
2497
2413 (>2.5σ(I))
334
Selected Bond Angles
Fe-P(1)-Mo
P(1)-Fe-C(4)
P(1)-Fe-C(5)
P(1)-Fe-C(6)
P(1)-Fe-C(7)
Mo-C(1)-O(1)
Mo-C(2)-O(2)
Mo-C(3)-O(3)
Fe-C(4)-O(4)
Fe-C(5)-O(5)
Fe-C(6)-O(6)
Fe-C(7)-O(7)
117.51(12)
90.3(4)
89.8(3)
178.1(6)
88.1(4)
177.7(12)
175.3(10)
174.1(13)
174.0(14)
178.3(8)
178(2)
Fe-P(1)-Mo
78.13(3)
121.95(4)
87.36(12)
88.48(13)
132.76(13)
52.735(24)
172.55(3)
176.4(3)
178.4(3)
177.7(4)
178.7(4)
175.9(3)
R
Rw
0.0372
0.0812
0.913
0.018
0.022
1.33
<0.17
P(1)-Fe-P(2)
P(1)-Fe-C(1)
P(1)-Fe-C(2)
P(1)-Fe-C(3)
P(1)-Fe-Mo
P(2)-Fe-Mo
Fe-C(1)-O(1)
Fe-C(2)-O(2)
Fe-C(3)-O(3)
Mo-C(4)-O(4)
Mo-C(5)-O(5)
S
∆F (e/Å3)
<0.691
0.16 g (82%). Anal. Calcd for C40H30FeO5P2Mo: C, 59.55; H,
3.76. Found: C, 59.15; H, 3.81. MS (FAB): M+, m/z 806.
Rea ction of 2 w ith P R3 (R ) P h , OMe) a n d P P h 2H. To
a yellow solution containing 0.18 mg (0.30 mmol) of 2 in 30
mL of THF was added 78 mg (0.30 mmol) of PPh3. The
solution was stirred in the dark at ambient temperature for
22 h. No color change was observed. The 31P NMR spectrum
of the reaction mixture indicated the presence of unreacted 2
and PPh3. The solution was then heated to reflux for 16 h.
After the solvent was removed, the residue was chromato-
graphed on grade I Al2O3 and eluted with CH2Cl2/hexane (1:
4) to afford a red band. After the solvent was removed, 3c
was obtained as a red solid. Yield: 0.20 g (82.7%). Similar
conditions were used for the reaction between 2 and PPh2H
or P(OMe)3. No complex 3 was observed among the reaction
products, according to 31P NMR spectra of the reaction
mixtures, when the reaction was carried out at room temper-
ature. After the solution was heated to reflux, complex 3 was
obtained.
175.5(13)
ite-monochromated Mo KR radiation. Structures were 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.
Crystal data and details of data collection and structure
analysis are summarized in Table 2. Selected interatomic
distances and bond angles are given in Table 3. The final
positional and displacement parameters for all atoms are
provided in the Supporting Information.
Ack n ow led gm en t. We are grateful to Dr. K. J . Lin
and Mr. Y. S. Wen at the Institute of Chemistry for the
single-crystal X-ray diffraction studies. We are also
grateful to the National Science Council of the Republic
of China and Academia Sinica for financial support of
this work.
Rea ction betw een 1 a n d CO. A solution of 1 (0.19 g, 0.33
mmol) in 20 mL of THF in a 100 mL Schlenk flask was stirred
under 1 atm of CO overnight at room temperature. A 31P NMR
study of the solution indicated that no reaction took place
between 1 and CO.
Str u ctu r e Deter m in a tion of Cp Mo(CO)3(µ-P P h 2)F e-
(CO)4 (2) a n d Cp Mo(CO)2(µ-P P h 2)F e(CO)3(P OMe3) (3a ).
Crystals of complexes 2 and 3a were grown by slow diffusion
of hexanes into the saturated CH2Cl2 solutions of the relevant
complexes at -15 °C in air. Diffraction measurements were
made using an Enraf-Nonius CAD4 diffractometer with graph-
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 compounds 2 and 3a (15 pages).
Ordering information is given on any current masthead page.
OM970786I