Abstraction of methyl from neutral Fischer-type carbene complexes: A new site for nucleophilic attack

Article abstract of DOI:10.1021/om960678g

Reactions of Fischer-type carbene complexes, M(CO)₅(C(OMe)Ph) (M = Cr, W), with metal carbonyl anions (M′^- = CpFe(CO)₂^-, Re(CO)₅^-, Mn(CO)₄PPh₃^-, Co(CO)₃PPh₃^-, Cp*Cr(CO)₃^-, CpMo(CO)₃^-) result in demethylation of the carbene complexes. The products are M(CO)₅C(O)Ph^- and M′-Me, characterized by infrared and NMR spectroscopy. A slower rate for reaction with W(CO)₅(C(OEt)Ph) in comparison to the methyl analogue is consistent with nucleophilic attack of the metal carbonyl anion on the methyl of the methoxy group of the carbene. This is a new type of nucleophilic attack on a Fischer-type carbene.

Full text of DOI:10.1021/om960678g

490
Organometallics 1997, 16, 490-493
Notes
Abstr a ction of Meth yl fr om Neu tr a l F isch er -Typ e
Ca r ben e Com p lexes: A New Site for Nu cleop h ilic Atta ck
Laurence M. Toomey and J im D. Atwood*
Department of Chemistry, University at Buffalo, State University of New York,
Buffalo, New York 14260-3000
Received August 9, 1996X
Summary: Reactions of Fischer-type carbene complexes,
carbon.6 Here, we report a series of reactions between
transition-metal carbonyl anions and neutral alkoxy-
carbene complexes which result in transfer of the alkyl
group of the alkoxy substituent to the metal carbonyl
anion. This transfer most likely corresponds to nucleo-
philic attack directly at the alkyl portion of the alkoxy
group of a neutral carbene and is the only example in
which this is the observed site of attack. This system
also represents an unusual example of oxygen-to-metal
alkyl transfer; a similar example is decomposition of the
heterodinuclear µ2-alkoxycarbyne complex Cp(CO)Fe-
(µ-COR)(µ-CO)Mn(CO)Cp′ (Cp′ ) η5-C5H4Me) described
by Hersh.7 A few examples of alkyl displacement from
the alkoxy group of cationic carbene complexes have
been reported.8,9 An example is8
M(CO)5(C(OMe)Ph) (M ) Cr, W), with metal carbonyl
-
anions (M′- ) CpFe(CO)2-, Re(CO)5-, Mn(CO)4PPh3
,
Co(CO)3PPh3-, Cp*Cr(CO)3-, CpMo(CO)3-) result in
demethylation of the carbene complexes. The products
are M(CO)5C(O)Ph- and M′-Me, characterized by in-
frared and NMR spectroscopy. A slower rate for reaction
with W(CO)5(C(OEt)Ph) in comparison to the methyl
analogue is consistent with nucleophilic attack of the
metal carbonyl anion on the methyl of the methoxy group
of the carbene. This is a new type of nucleophilic attack
on a Fischer-type carbene.
In tr od u ction
Transition-metal carbene complexes have received
considerable attention for their involvement in reactions
such as olefin metathesis, olefin cyclopropanation, and
Fischer-Tropsch synthesis.1 Among the many impor-
tant reactions of carbene complexes is nucleophilic
attack on the carbene. Alkoxycarbene complexes (Fis-
cher-type carbene complexes) undergo nucleophilic at-
tack at the carbene carbon.2 This site of nucleophilic
attack contradicts Mulliken population studies, which
have indicated that the carbon atoms of the cis-carbonyl
ligands carry the greatest positive charge.3 The justi-
fication provided for the observed site of attack is that
the lowest unoccupied molecular orbital (LUMO) is
spatially and energetically localized on the carbene
carbon; therefore, the nucleophilic attack is frontier-
orbital-controlled and not simply charge-controlled.3,4
Nucleophilic attack at the carbene carbon can be sup-
pressed to the cis-carbonyl ligands by placing a formal
negative charge at the carbene carbon as for anionic acyl
metalates.5 Hegedus recently reported that nucleophilic
attack can be directed toward the cis-carbonyl ligands
by deprotonation at the R-position, again resulting in
formation of a formal negative charge at the carbene
CpFe(CO)(PPh3)(dC(OEt)Me)+ + I-
f
CpFe(CO)(PPh3)(C(O)Me) + EtI (1)
indicating that for such a cationic carbene the alkyl on
the alkoxy group carries significant positive charge.
Exp er im en ta l Section
Ma ter ia ls. Mn2(CO)10, Re2(CO)10, Cp2Fe2(CO)4, Cp2Mo2-
(CO)6, Co2(CO)8, W(CO)6, Cr(CO)6, and Fe(CO)5 were pur-
chased from Strem Chemical Co. and used as received.
[PPN][Cl] (PPN ) bis(triphenylphosphine)nitrogen(1+)), C6H5-
Li, (CH3)3OBF4, and (CH3CH2)3OBF4 were purchased from
Aldrich Chemical Co. Solvents were dried and degassed prior
to use.
In str u m en ta l Mea su r em en ts. Infrared spectra were
recorded on a Mattson Polaris Fourier transform spectrometer
using 0.5 mm NaCl solution cells or KBr disks. All spectra
are reported in wavenumbers (cm-1). 1H NMR spectra were
recorded on a Varian VXR-400, with the reference set to
residual solvent peaks. All chemical shifts are reported in
ppm, and all coupling constants (J ) are reported in Hz.
P r ep a r a tion s. Syntheses were accomplished under an
inert atmosphere of dry nitrogen or argon using glovebox,
Schlenk, or high-vacuum techniques. The complexes [PPN]-
X Abstract published in Advance ACS Abstracts, J anuary 15, 1997.
(1) For a review see: (a) Brown, F. J . Inorg. Chem. 1980, 27, 1. (b)
Do¨tz, K. H. Transition Metal Carbene Complexes; Seyferth, D., Ed.;
Verlag Chemie: Deerfield Beach, FL, 1983. (c) Fischer, E. O. Adv.
Organomet. Chem. 1976, 14, 1.
(2) Fischer, H. Mechanistic Aspects of Carbene Complex Reactions.
In Transition Metal Carbene Complexes; Seyferth, D., Ed.; Verlag
Chemie: Deerfield Beach, FL, 1983; pp 248-259.
(3) (a) Block, T. F.; Fenske, R. F.; Casey, C. P. J . Am. Chem. Soc.
1976, 98, 441. (b) Block, T. F.; Fenske, R. F. J . Organomet. Chem.
1977, 139, 235.
(6) Wieber, G. M.; Hegedus, L. S.; Gale, C. Organometallics 1995,
14, 3574.
(7) (a) Fong, R. H.; Hersh, W. H. Organometallics 1985, 4, 1468.
(b) Fong, R. H.; Lin, C. H.; Idmoumaz, H.; Hersh, W. H. Organome-
tallics 1993, 12, 503. (c) Idmoumaz, H.; Lin, C. H.; Hersh, W. H.
Organometallics 1993, 12, 503.
(8) (a) Davison, A.; Reger, D. L. J . Am. Chem. Soc. 1972, 94, 9237.
(b) Cutler, A. R. J . Am. Chem. Soc. 1979, 101, 604.
(9) (a) Green, M. L. H.; Mitchard, L. C.; Swanwick, M. G. J . Chem.
Soc. A 1971, 794. (b) Treichel, P. M.; Wagner, K. P. J . Organomet.
Chem. 1975, 88, 199.
(4) Kostic, N. M.; Fenske, R. F. Organometallics 1982, 1, 974.
(5) (a) Fischer, E. O.; Kreissl, F. R.; Kreiter, C. G.; Meineke, E. W.
Chem. Ber. 1972, 105, 2558. (b) Darst, K. P.; Lenhert, P. G.; Lukehart,
C. M.; Warfield, L. T. J . Organomet. Chem. 1980, 195, 317.
S0276-7333(96)00678-4 CCC: $14.00 © 1997 American Chemical Society

Notes
Organometallics, Vol. 16, No. 3, 1997 491
Ta ble 1. Ch a r a cter iza tion Da ta of th e Meth yl P r od u cts a n d Tim es of Rea ction s for Meta l Ca r bon yl An ion s
a n d Meth oxyp h en ylca r ben e Com p lexes
anion (M′)
products
IR (νCO), cm-1
1H NMR (acetonitrile-d3), ppm (J , Hz)
timeh
2-
- c
Fe(CO)4
CH3Fe(CO)4
1922 (m), 1874 (s)a
0.13 (s)
0.10 (s), 4.85 (s)
-0.26 (s)
-0.51 (d) (J Hz ) 7.6), 7.50 (mult)
0.90 (d) (J Hz ) 2.0), 7.50 (mult)
0.33 (s), 5.40 (s)
a few seconds
a few seconds
1 h
14 h
1.5 days
5 days
2014 (s), 1960 (s)b
-
d
CpFe(CO)2
CH3CpFe(CO)2
2127 (w), 2013 (s), 1978 (s)b
2056 (w), 1985 (m), 1969 (s), 1939 (m)b
2039 (w), 1983 (w), 1966 (vs)b
2024 (m), 1941 (s)b
-
d
Re(CO)5
CH3Re(CO)5
-
e
Mn(CO)4PPh3
Co(CO)3PPh3
CpMo(CO)3
CH3Mn(CO)4PPh3
CH3Co(CO)3PPh3
CH3CpMo(CO)3
CH3Cp*Cr(CO)3
-
f
-
d
1998 (s), 1925 (s), 1919 (sh)b
0.24 (s), 1.79 (s)
6 days
-
g
Cp*Cr(CO)3
-
Co(CO)4
no reacn
a
b
In THF. In hexanes. c Arndt, L. W.; Bancroft, B. T.; Darensbourg, M. Y.; J anzen, C. P.; Kim, C. M.; Reibenspies, J .; Varner, K. E.;
Youngdahl, K. A. Organometallics 1988, 7, 1302. Davison, A.; McCleverty, J . A.; Wilkinson, G. J . Chem. Soc. 1963, 1133. e Kraihanzel,
d
C. S.; Maples, P. K. J . Am. Chem. Soc. 1965, 22, 5268. f King, R. B. Adv. Organomet. Chem. 1964, 2, 157. J aeger, T. J .; Baird, M. C.
g
h
Organometallics 1988, 7, 2074. The time quoted is the time required for half of the metal carbonyl anion to be consumed.
Ta ble 2. Ca r bon yl Str etch in g F r equ en cies for Acyl
Meta la tes F or m ed in Rea ction s in THF
investigated reacted with the neutral methoxyphenyl-
carbene complexes, resulting in transfer of the methyl
substituent from the alkoxy oxygen to the metal carbo-
nyl anion (reaction 2). The reactions and characteriza-
tion data for the products formed in these reactions are
listed in Tables 1 and 2. The metal carbonyl dimer M′2
was not a product in any of the reactions.
acyl metalate
ν
CO, cm-1
[PPN][(CO)5CrC(O)Ph)]
[PPN][(CO)5WC(O)Ph)]
[Na][(CO)5CrC(O)Ph)]
2025 (w), 1895 (vs), 1861 (m)
2040 (w), 1895 (vs), 1861 (m)
2040 (w), 1895 (vs), 1880 (m)
[CpFe(CO)2],8 [PPN][Re(CO)5],10 [PPN][Mn(CO)4(PPh3)],10 [PPN]-
[Co(CO)3(PPh3)],10 [PPN][Co(CO)4],10 [PPN][Cp*Cr(CO)3],11 [PP-
N][CpMo(CO)3],12 Na2Fe(CO)4,13 (CO)5MdC(OCH3)Ph (M ) Cr,
W),14 and (CO)5WdC(OCH2CH3)Ph15 were prepared by litera-
ture procedures. The spectroscopic characterizations were in
excellent agreement with those previously reported.14,15
(CO)5WdC(OMe)Ph: IR (hexane), 2070 (w), 1985 (w), 1950
(CO)5MdC(OCH3)Ph + [M′]- f
[(CO)5MC(O)Ph]- + M′CH3
M ) Cr, W
1
(vs), and 1941 (vs) cm-1; H NMR (CD3CN), 4.73 (s) and 7.50
(m) ppm. (CO)5WdC(OCH2CH3)Ph: IR (hexane), 2070 (w),
M′ ) CpFe(CO)2, Re(CO)5, Mn(CO)4PPh3,
1983 (w), 1954 (vs), and 1947 (vs) cm-1 1H NMR (CD3CN),
;
Co(CO)3PPh3, Cp*Cr(CO)3, CpMo(CO)3 (2)
1.65 (t), 5.05 (q), and 7.46 (m) ppm. (CO)5CrdC(OMe)Ph: IR
(hexane), 2064 (m), 1987 (w), 1964 (s), 1954 (vs), and 1943 (sh)
The formation of the acyl metalate M(CO)5C(O)Ph-
was verified by reaction with 1 equiv of trimethyloxo-
nium tetrafluoroborate, which regenerated the corre-
sponding carbene in each instance (reaction 3).
cm-1
. The carbonyl stretching frequencies for the metal
carbonyl anions are shown in Table S1 (Supporting Informa-
tion).
P r od u ct Stu d ies. For determination of products, equal
volumes of 2 × 10-4 M THF solutions of metal carbonyl anion
and transition-metal carbene complex were mixed at ambient
temperature in an inert-atmosphere glovebox. The reactions
were monitored using infrared spectroscopy for times varying
from a few seconds to a week. After completion, the THF was
removed in vacuo and the resulting solids were washed with
hexane, extracting all neutral products. The residual ionic
products were then extracted using either THF or diethyl
ether. All product determinations were done by infrared and
1H NMR spectroscopy (Tables 1 and 2).
[(CO)5MC(O)Ph]- + (CH3)3OBF4 f
(CO)5MdC(OCH3)Ph (3)
M ) Cr, W
1
A low-temperature H NMR spectroscopic examina-
tion of the reaction between [PPN][Mn(CO)4(PPh3)] and
(CO)5WdC(OCH3)Ph indicates clean conversion to prod-
ucts. At -70 °C, the spectrum contained only peaks
from the starting materials. Only at room temperature
(18 °C) was there evidence of reaction, with the appear-
ance of a new peak attributed to CH3Mn(CO)4(PPh3)
(-0.51 (d) ppm (J P-H ) 7.6 Hz)). A gradual decrease
in the methoxy peak of (CO)5WdC(OCH3)Ph (4.87 (s)
ppm) coupled with an increase in the new methyl signal
was observed over a 5-day period.
Kin etic Stu d ies. Reactions of W(CO)5(C(OR)Ph) (R ) Me,
-
Et) with Mn(CO)4PPh3 were studied kinetically. The reac-
tions were followed by disappearance of Mn(CO)4PPh3- (1814
cm-1) with the carbene in excess. Concentrations of Mn(CO)4-
PPh3- were in the range of (5.0-6.0) × 10-4 M, and the carbene
concentrations were in the range of 5.0 × 10-3 M to 0.0201 M.
For R ) Me the k value was obtained as a plot of kobsd versus
[W(CO)5(C(OMe)Ph)]. For R ) Et k was determined by
dividing the pseudo-first-order rate constant by the concentra-
tion of W(CO)5(C(OEt)Ph). Error limits in k and kobsd are
standard deviations.
For the anions investigated, the reactivity suggests
+
that the rate of CH3 transfer occurs in the order
Cp*Cr(CO)3- < CpMo(CO)3- < Co(CO)3(PPh3)- <
Resu lts
Mn(CO)4(PPh3)- < Re(CO)5- , CpFe(CO)2
-
Mon oa n ion Rea ction s. With the exception of [PPN]-
[Co(CO)4], which did not react, all metal carbonyl anions
The time required for half of the reactants to be
consumed ranged from 6 days for Cp*Cr(CO)3- to a few
seconds for CpFe(CO)2 (see Table 1), in reasonable
(10) Zhen, Y.; Feighery, W. G.; Lai, C. K.; Atwood, J . D. J . Am. Chem.
Soc. 1989, 111, 7832.
(11) King, R. B.; Efraty, A.; Douglas, W. M. J . Organomet. Chem.
1973, 60, 125.
(12) Ruff, J . K.; Schlientz, W. J . Inorg. Synth. 1979, 15, 87.
(13) Zhen, Y.; Atwood, J . D. Organometallics 1991, 10, 2778.
(14) (a) Fischer, E. O.; Maasbo¨l, A. Chem. Ber. 1967, 100, 2445. (b)
Aumann, R.; Fischer, E. O. Angew. Chem., Int. Ed. Engl. 1967, 6, 879.
(15) Fischer, E. O.; Maasbo¨l, A. J . Organomet. Chem. 1968, 12, P15.
-
agreement with the nucleophilicity of the metal carbonyl
anion.16 Only Co(CO)3PPh3- (faster than expected) was
(16) Lai, C. K.; Feighery, W. F.; Zhen, Y.; Atwood, J . D. Inorg. Chem.
1989, 28, 3929.

492 Organometallics, Vol. 16, No. 3, 1997
Notes
Sch em e 1. P ossible Sites for Nu cleop h ilic Atta ck
significantly different. The metal carbonyl anion
Co(CO)4-, which is the weakest nucleophile, exhibited
no reaction with the carbene complexes.
on F isch er -Typ e Ca r ben es
To determine the dependence on the alkyl group
transferred, kinetic studies of the reactions of W(CO)5-
(C(OMe)Ph) and W(CO)5(C(OEt)Ph) with PPNMn-
(CO)4PPh3 were conducted. The methoxycarbene com-
plex was studied fully, showing the rate law
rate )
k[[PPN][Mn(CO)4PPh3]][W(CO5)(C(OMe)Ph)]
with k ) 0.14 ( 0.01 s-1 M-1 at 28 °C. For the
ethoxycarbene the observed pseudo-first-order rate con-
stant was divided by the concentration of the carbene
complex, giving k ) (2.0 ( 0.7) × 10-3 s-1 M-1
.
Rea ction w ith Tetr a ca r bon ylfer r a te(2-). Reac-
tion of Na2Fe(CO)4 with (CO)5WdC(OCH3)Ph was also
investigated and cleanly provides the products expected
from a methyl transfer (reaction 4). The reaction was
the alkyl substituent or (ii) nucleophilic attack of the
metal anion at the carbene carbon followed by a
subsequent methyl migration to the anion. Nucleophilic
attack directly at the alkyl substituent should result in
a large effect of the alkyl substituent being transferred
on the rate.20 The second potential mechanism (ii)
would require that the initial nucleophilic attack at the
carbon be rate-determining and the subsequent methyl
migration to be rapid, since there was no evidence of
the bridging carbene intermediate. We would also
expect a much smaller dependence on the organic
fragment transferred if the reaction followed pathway
ii.
Fe(CO)42- + (CO)5WdC(OCH3)Ph f
CH3Fe(CO)4- + (CO)5WC(O)Ph- (4)
complete within seconds, consistent with the estimated
nucleophilicity of Na2Fe(CO)4.17
Discu ssion
The reaction under consideration is demethylation of
the methoxy group of a neutral tungsten or chromium
carbene complex (reaction 2) by a metal carbonyl anion.
While this reaction is unprecedented, a desilylation has
been reported:18
The methoxy complex W(CO)5(C(OMe)Ph) reacts with
-
Mn(CO)4PPh3 70 times more rapidly than the ethoxy
complex W(CO)5(C(OEt)Ph). Such a slowing for C2H5
in comparison to CH3 is typical for direct nucleophilic
attack at carbon,20 consistent with the mechanism
shown as (i) in Scheme 1.
OSiMe3
C
W(CO)5
+ NaOMe
Na[W(CO)5(C(O)R)] + MeOSiMe3
R
(5)
Nucleophilic attack at Fischer-type carbene complexes
is well-known1 and is a distinguishing feature for
Fischer-type carbene complexes in comparison to early-
transition-metal alkylidene complexes, which are sus-
ceptible to electrophilic attack. However, the reactions
reported in this paper evidently represent the first
examples of nucleophilic attack at the alkoxy carbon
group. Calculations show that the alkoxy methyl car-
ries a positive charge3 but is the least likely of the three
sites for nucleophilic attack. The significant rate de-
pendence on the alkyl group is inconsistent with attack
at the carbene carbon or at the cis carbonyl. Why then
do metal carbonyl anions attack (CO)5M(C(OMe)Ph)
exclusively at the methyl? Earlier studies on alkyl
transfer reactions between metal carbonyl anions indi-
cated transfer occurred when the reactant anion is more
nucleophilic than the product anion. Evidently M(CO)5-
C(O)Ph- is a weak nucleophile and a thermodynamic
driving force for methyl transfer exists. It is likely that
the relatively large metal carbonyl anions cannot access
the carbene carbon or carbonyl carbon but can interact
with the methyl which is further removed from the
group 6 metal center.
R = C4H3S
A similar reaction was observed with LiPh. Methanol
and amines also attacked the silyl group, while PMe3
attacked the carbene carbon. The discussion centered
on πp-πd bonding; similar reactions were not observed
in the absence of the silyl group.18 Cationic carbene
complexes (reaction 1) have been dealkylated by I-,
phosphine ligands, and MeLi.7-9 However, the nucleo-
philic attack by a metal carbonyl anion on the alkyl part
of the alkoxy group (reaction 2) appears to be unprec-
edented.
Mech a n ism . The reactions described by reaction 2
involve transfer of the alkyl substituent from the alkoxy
oxygen of the carbene to the metal carbonyl anion.
Metal carbonyl anions react as nucleophilic or single-
electron-transfer reagents.19 Single-electron reactions
invariably produce metal carbonyl dimers; no dimers
were observed in the reactions represented by reaction
2. Thus, reaction 2 most likely proceeds through
nucleophilic attack through two possible sites (Scheme
1): (i) nucleophilic attack by the metal anion directly at
Decomposition of Cp(CO)Fe(µ-COR)(µ-CO)MnCp′(CO)-
(Cp′ ) η5-C5H4Me) produces MeFeCp(CO)2 and Cp′Mn-
(17) Wang, P.; Atwood, J . D. Organometallics 1993, 12, 4247.
(18) Fischer, E. O.; Selmayr, T.; Kreissl, F. R.; Schubert, U. Chem.
Ber. 1977, 110, 2574.
(19) Atwood, J . D.; Corraine-Pandolfino, M. S.; Zhen, Y.; Striejewske,
W. S.; Lai, C. K.; Wang, P. J . Coord. Chem. 1994, 32, 65 and references
therein.
(20) (a) Wang, P.; Atwood, J . D. J . Am. Chem. Soc. 1992, 114, 6424.
(b) March, J . Advanced Organic Chemistry, 3rd ed.; Wiley: New York,
1985; pp 298-300.

Notes
Organometallics, Vol. 16, No. 3, 1997 493
(CO)3 in a transfer of an alkyl from a bridging carbyne
to a metal.7 While this provides precedent for alkyl
transfer from an alkoxy on a carbene, it does not seem
to be mechanistically related. Two reactions have been
reported where nucleophilic attack by a metal carbonyl
anion on a cationic carbene complex result in heterobi-
metallic complexes with bridging carbene groups:21,22
indication that neutral carbene complexes offer the
same two sites, depending on the nucleophile.
Con clu sion
Formally, one can consider the transfer of the alkyl
group as a nucleophilic competition for R+ between the
acyl metalate and the metal anion. We can therefore
estimate the nucleophilicity of the acyl metalates:
2-
-
Fe(CO)4 ≈ CpFe(CO)2- > Re(CO)5
>
CpFe(CO)(PPh3)(dCH(OMe))+ + CpFe(CO)2- f
Cp2(CO)2(µ-CH(OMe))(µ-CO)Fe2 + PPh3 (6)
Mn(CO)4(PPh3)- > Co(CO)3(PPh3)- >
CpMo(CO)3- > Cp*Cr(CO)3- > W(CO)5(C(O)Ph)- ≈
CpFe(CO)(CH3CN)(dC(SMe)2)+ + Co(CO)4- f
Cp(CO)Fe(µ-C(SMe)2)(µ-CO)Co(CO)3 + CH3CN (7)
-
Cr(CO)5(C(O)Ph)- > Co(CO)4
The reported reactions show a new site for nucleophilic
attack on neutral Fischer-type carbene complexes.
Reaction 7 is not easily compared to the reactions
reported in this paper, but reaction 6 indicates attack
Ack n ow led gm en t. We are grateful to the Depart-
ment of Energy, Grant No. ER 13775, for support of this
research.
-
by CpFe(CO)2 at the carbene carbon. The similarity
of the reactants in reactions 1 and 6 indicates that
cationic carbene complexes are susceptible to attack by
nucleophiles at either the carbon of the carbene or the
alkyl of the alkoxy group on the carbene. The reactions
reported in this paper (reaction 2) provide the first
Su p p or tin g In for m a tion Ava ila ble: A table of IR fre-
quencies for metal carbonyl anions and absorbance vs time
plots for the reaction of W(CO)5(C(OMe)Ph) with [PPN][Mn-
(CO)4PPh3] and of W(CO)5(C(OEt)Ph) with [PPN][Mn(CO)4PPh3]
(5 pages). Ordering information is given on any current
masthead page.
(21) Kao, S. C.; Lu, P. P. Y.; Pettit, R. Organometallics 1982, 1, 911.
(22) Matachek, J . R.; Angelici, R. J . Organometallics 1982, 1, 1541.
OM960678G