Synthesis and characterization of functionally substituted cyclopentadienyl derivatives of silver and copper

Article abstract of DOI:10.1021/om000618h

A series of functionally substituted cyclopentadienyl derivatives of silver and copper have been synthesized and characterized. Reactions between sodium acetyl- or carbomethoxycyclopentadienylide, triphenylphosphine, and silver triflate (AgSO₃CF₃) in DME produced Ag[C₅H₄C(O)CH₃](PPh₃) and Ag[C₅H₄CO₂CH₃](PPh₃) in yields of 57-58%. Corresponding copper analogues were prepared using [BrCu(PPh₃)]₄. Similar reactions between sodium acetyl- or carbomethoxycyclopentadienylide and AgSO₃CF₃ in the presence of the bidentate ligand 1,2-bis(diphenylphosphino)ethane afforded the chelated compounds Ag[C₅H₄C(O)CH₃] [Ph₂P(CH₂)₂-PPh₂] and Ag[C₅H₄CO₂CH₃][Ph₂P(CH₂)₂ PPh₂] in 55-72% yields. Dinuclear compounds of the type [Ag(C₅H₄PPh₂)(PR₃)]₂ (R = Ph, Et) resulted in 36-49% yield from reactions of silver chloride with the appropriate phosphine in refluxing toluene, followed by cooling to -78°C and subsequent reactions with lithium diphenylphosphinocyclopentadienide. The compounds M(C₅Ph₅)(PEt₃) (M = Ag, Cu) containing five bulky phenyl substituents were obtained in 44-56% yield from reactions of sodium pentaphenylcyclopentadienide and [ClM(PEt₃)]₄ in THF. In general, the new organosilver compounds containing functional substituents on the cyclopentadienyl ring as well as binuclear phosphine derivatives exhibited enhanced thermal and oxidative stabilities compared with the parent compound Ag(C₅H₅)(PPh₃). ³¹P NMR studies of the compounds have been undertaken and are in agreement with the proposed structures.

Full text of DOI:10.1021/om000618h

4060
Organometallics 2000, 19, 4060-4065
Syn th esis a n d Ch a r a cter iza tion of F u n ction a lly
Su bstitu ted Cyclop en ta d ien yl Der iva tives of Silver a n d
Cop p er
Linda Lettko and Marvin D. Rausch*
Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003
Received J uly 17, 2000
A series of functionally substituted cyclopentadienyl derivatives of silver and copper have
been synthesized and characterized. Reactions between sodium acetyl- or carbomethoxycy-
clopentadienylide, triphenylphosphine, and silver triflate (AgSO3CF3) in DME produced Ag-
[C5H4C(O)CH3](PPh3) and Ag[C5H4CO2CH3](PPh3) in yields of 57-58%. Corresponding copper
analogues were prepared using [BrCu(PPh3)]4. Similar reactions between sodium acetyl- or
carbomethoxycyclopentadienylide and AgSO3CF3 in the presence of the bidentate ligand 1,2-
bis(diphenylphosphino)ethane afforded the chelated compounds Ag[C5H4C(O)CH3][Ph2P(CH2)2-
PPh2] and Ag[C5H4CO2CH3][Ph2P(CH2)2PPh2] in 55-72% yields. Dinuclear compounds of
the type [Ag(C5H4PPh2)(PR3)]2 (R ) Ph, Et) resulted in 36-49% yield from reactions of silver
chloride with the appropriate phosphine in refluxing toluene, followed by cooling to -78 °C
and subsequent reactions with lithium diphenylphosphinocyclopentadienide. The compounds
M(C5Ph5)(PEt3) (M ) Ag, Cu) containing five bulky phenyl substituents were obtained in
44-56% yield from reactions of sodium pentaphenylcyclopentadienide and [ClM(PEt3)]4 in
THF. In general, the new organosilver compounds containing functional substituents on
the cyclopentadienyl ring as well as binuclear phosphine derivatives exhibited enhanced
thermal and oxidative stabilities compared with the parent compound Ag(C5H5)(PPh3). 31P
NMR studies of the compounds have been undertaken and are in agreement with the
proposed structures.
In tr od u ction
bridging carbene and carbyne metal ligands11 have been
described. The vinyl and isopropenyl analogues Cu-
[C5H4C(R)dCH2](PEt3) (R ) H, Me) are also known,3
and the molecular structures of (η5-methylcyclopenta-
dienyl)(triphenylphosphine)copper(I)12 and (η5-pentaphen-
ylcyclopentadienyl)(triphenylphosphine)copper(I)13 have
been reported.
The synthesis, structure, and reactivity of cyclopen-
tadienyl compounds that contain functional substituents
has become an important area of research in organo-
metallic chemistry.1-6 Of special importance is the
application of functionally substituted metallocenes of
group 4 metals as homogeneous catalysts for the po-
lymerization of R-olefins to stereoregular polyolefins.7,8
In contrast with the rapidly developing chemistry of
functionally substituted cyclopentadienyl derivatives of
the early transition metals, corresponding derivatives
of the group 11 metals copper and silver have been much
less studied. A series of pentamethylcyclopentadienyl-
copper compounds that also contain phosphine,9 carbo-
nyl,9 acetylene,9 hexaphenylcarbodiphosphorane,10 and
The chemistry of functionally substituted cyclopen-
tadienylsilver compounds is even more limited. The first
cyclopentadienylsilver compound was described in 1976
by Van der Kerk and co-workers.14 (η5-Cyclopentadi-
enyl)(triphenylphosphine)silver(I) (1) was produced by
treatment of a solution of sodium cyclopentadienide and
triphenylphosphine in THF with a solution of silver
trifluoromethanesulfonate (triflate) in THF at -80 °C.
Compound 1 was reported to be moisture, air, and
temperature sensitive in the solid state and in solution.
It could be stored at -80 °C without change, but
decomposed within seconds at 75 °C. Subsequent studies
confirmed the extreme air, moisture, and thermal
instability of 1, but demonstrated that it was a useful
intermediate in the synthesis of phosphine-stabilized
(1) Hart, W. P.; Macomber, D. W.; Rausch, M. D. J . Am. Chem. Soc.
1980, 102, 1196.
(2) Hart, W. P.; Macomber, D. W.; Rausch, M. D. Adv. Organomet.
Chem. 1982, 21, 1.
(3) Macomber, D. W.; Hart, W. P.; Rausch, M. D.; Priester, R. D.;
Pittman, C. U., J r. J . Am. Chem. Soc. 1982, 104, 884.
(4) J aniak, C.; Schumann, H. Adv. Organomet. Chem. 1991, 33, 291.
(5) Mo¨hring, P. C.; Coville, N. J . J . Organomet. Chem. 1994, 479, 1.
(6) (a) Blais, M. S.; Rausch, M. D. Organometallics 1994, 13, 3557.
(b) Blais, M. S.; Rausch, M. D. J . Organomet. Chem. 1995, 502, 1.
(7) Spaleck, W.; Kuber, F.; Winter, A.; Rohrmann, J .; Bachman, B.;
Antberg, M.; Dolle, V.; Paulus, E. Organometallics 1994, 13, 954.
(8) Schneider, N.; Huttenloch, M. E.; Stehling, U.; Kirsten, R.;
Schaper, F.; Brintzinger, H. H. Organometallics 1997, 16, 3413.
(9) Macomber, D. W.; Rausch, M. D. J . Am. Chem. Soc. 1983, 105,
5325.
(11) Carriedo, G. A.; Howard, J . A. K.; Stone, F. G. A. J . Chem. Soc.,
Dalton Trans. 1984, 1555.
(12) Hanusa, T. P.; Ulibarri, T. A.; Evans, W. J . Acta Crystallogr.
1985, C41, 1036.
(13) Anderson, Q. T.; Erkizia, E.; Conry, R. R. Organometallics 1988,
17, 4917.
(14) Hofstee, H. K.; Boersma, J .; Van der Kerk, G. J . M. J .
Organomet. Chem. 1976, 120, 313.
(10) Zybill, C.; Mu¨ller, G. Organometallics 1987, 6, 2489.
10.1021/om000618h CCC: $19.00 © 2000 American Chemical Society
Publication on Web 09/06/2000

Cyclopentadienyl Derivatives of Ag and Cu
Organometallics, Vol. 19, No. 20, 2000 4061
silver acetylide complexes.15 Bruce and co-workers16
have described the formation and structure of several
silver complexes that contain C5(CO2Me)5 ligands, and
(η5-pentamethylcyclopentadienyl)(hexaphenylcarbo-
diphosphorane)silver(I), analogous to the related orga-
nocopper compound mentioned above, has been re-
ported.10
The central objective of the present study was to
prepare cyclopentadienylsilver compounds that contain
various functional substituents on the cyclopentadienyl
ring, to compare the properties of these compounds with
the parent compound 1, and to examine structural
features of the new organosilver compounds by means
Compounds 2 and 3 could also be synthesized by a
more direct route. By reacting equimolar amounts of
sodium acetyl- or carbomethoxycyclopentadienide with
mono(triphenylphosphine)silver triflate under the same
conditions as described above, 2 and 3 were obtained
in comparable yields. The organosilver compounds 2 and
1
of H and 31P NMR techniques. During the course of
this investigation, several analogous new cyclopenta-
dienylcopper compounds have likewise been prepared
and are discussed.
1
3 were characterized by their H NMR, 31P NMR (vide
Resu lts a n d Discu ssion
infra), and IR spectra, as well as by elemental analysis.
Compared with 1, compounds 2 and 3 were much
more stable in air. On heating, 2 and 3 began to
decompose at 50 °C, but were air stable for days at room
temperature. In contrast, 1 is reported to be thermally
unstable, decomposing in a matter of minutes to a black
solid if left under an inert atmosphere at room temper-
ature.14,15 Compounds 2 and 3 were also appreciably less
moisture sensitive than 1.
The analogous copper compounds 4 and 5 were also
prepared and characterized from reactions of either
sodium acetyl- or carbomethoxycyclopentadienide with
tetrakis[bromotriphenylphosphinecopper] in THF solu-
tion. The organocopper compounds 4 and 5 were much
To expand the area of cyclopentadienylsilver chem-
istry, several approaches have been undertaken which
should lead to analogues of 1 that possess enhanced
overall stability. First, derivatives of 1 that contain
electron-withdrawing substituents have been synthe-
sized. Groups that can withdraw electron density away
from the five-membered ring and in effect away from
the metal center often tend to increase the stability of
cyclopentadienylmetal compounds.2 For example, Cu-
[η5-C5H4C(O)CH3](PEt3), which contains an electron-
withdrawing acetyl substituent on the cyclopentadienyl
ring, is appreciably more air stable than either Cu(η5-
C5H5)(PEt3) or Cu(η5-C5Me5)(PEt3).9
A second approach, which has been used in conjunc-
tion with the first approach, has been to study the effect
of a bidentate phosphine ligand. Monodentate phosphine
ligands are clearly important in forming cyclopentadi-
enylsilver compounds such as 1,14,15 and increased
stability might result from the use of a chelating
bidentate phosphine ligand such as 1,2-bis(diphenylphos-
phino)ethane.
A third approach has been to utilize highly substi-
tuted cyclopentadienyl ligands that contain five phenyl
substituents. These bulky ligands are known to impart
kinetic stabilization by means of shielding the reactive
metal center and making the compound less susceptible
to decomposition as a result of steric hindrance.4
The synthesis of monodentate phosphine derivatives
of silver and copper compounds was accomplished by
utilizing electron-withdrawing groups on the cyclopen-
tadienyl ring. The most effective groups for this study
were acetyl and carbomethoxy. The phosphine chosen
was triphenylphosphine due to its favorable solubility,
ease of handling, and crystallization properties. In the
case of silver, the acetyl (2) and carbomethoxy (3)
derivatives could be obtained in good yields by addition
of silver triflate to a solution of equimolar amounts of
sodium acetyl- or carbomethoxycyclopentadienide and
triphenylphosphine in DME at -10 °C. After filtration,
washing with cold DME, and drying, 2 and 3 were
obtained as off-white moderately air-stable solids.
more thermally and oxidatively stable than the silver
analogues 2 and 3. Compared with the latter, 4 and 5
decomposed on heating at temperatures of 90 and 120
°C, respectively. Both 4 and 5, like 2 and 3, were also
moderately air stable, but were much more stable in
solution at ambient temperatures than were 2 or 3.
Synthetic studies related to the formation of 2 and 3
but utilizing the potentially chelating bidentate ligand
1,2-bis(diphenylphosphino)ethane instead of triphen-
ylphosphine were subsequently undertaken. Com-
pounds 6 and 7 were prepared in DME at 0 °C from
reactions of 1,2-bis(diphenylphosphino)ethane, sodium
acetyl- or carbomethoxycyclopentadienide, and silver
triflate, or from reactions of [1,2-bis(diphenylphosphino)]-
silver(I) triflate and sodium acetyl- or carbomethoxy-
cyclopentadienide under the same conditions. After
workup, 6 and 7 were obtained in yields of 72% and
55%, respectively. Both 6 and 7 were moderately air
stable, decomposing on heating to 70 °C, and were more
stable in solution than the triphenylphosphine ana-
logues 2 and 3.
(15) Brasse, C.; Raithby, P. R.; Rennie, M. A.; Russell, C. A.; Steiner,
A.; Wright, D. S. Organometallics 1996, 15, 639.
(16) Bruce, M. I.; Williams, M. L.; Skelton, B. W.; White, A. H. J .
Chem. Soc., Dalton Trans. 1983, 799.

4062 Organometallics, Vol. 19, No. 20, 2000
Lettko and Rausch
In view of the successful formation of 6 and 7, several
attempts were made to synthesize related bis(triphen-
ylphosphine) complexes (8). However, reactions of either
sodium acetyl- or carbomethoxycyclopentadienide with
bis(triphenylphosphine)silver(I) triflate produced only
the monophosphine analogues 2 or 3 as well as the free
ligand triphenylphosphine. Similar results were ob-
tained starting with bis(triphenylphosphine)copper tri-
flate. The monophosphine complexes 4 and 5 were ob-
tained, and no bis(triphenylphosphine) derivatives (8)
could be isolated.
Cyclopentadienylsilver compounds have also been
synthesized that contain the diphenylphosphinocyclo-
pentadienyl ligand. This ligand is unique in that it leads
to stabilized dinuclear complexes where the phosphorus
atom attached to the ring bridges a second metal center.
Two complexes (9, 10) were obtained from reactions of
(PR3) analogues are known to be considerably more air
sensitive than the parent compounds (η5-C5H5)Cu(PR3).9
The cyclopentadienylsilver compounds synthesized in
this study have also been characterized by 31P NMR
techniques, including variable-temperature solution
NMR and solid-state NMR. 31P NMR is a valuable tool
in this regard, since silver has two NMR active isotopes.
107Ag and 109Ag are both spin one-half nuclei with high
natural abundances of 52% and 48%, respectively. At
ambient temperatures in solution, Ag-P coupling is
generally very broad in silver-phosphine compounds,
due to rapid ligand exchange on the NMR time scale.
However, the coupling can be observed in the solid state
or at low temperatures in solution.17-19
For the organosilver compounds 2 and 3, broad
singlets were observed in the 31P NMR spectra at 20 °C
and broad doublets at -70 °C. The broadening is
consistent with ligand exchange between the phosphine
and the cyclopentadienylsilver moiety, and the low
temperature doublet is consistent with bonding between
phosphorus and silver. For 2, the doublet was centered
equimolar amounts of silver chloride with the appropri-
ate phosphine in refluxing toluene. After cooling the
solution to -78 °C, lithium diphenylphosphinocyclopen-
tadienide was added, and the reaction mixture was
allowed to stir for several hours before crystallization
at -20 °C. Compounds 9 and 10 were obtained in yields
of 49% and 36%, respectively.
Organosilver complexes 9 and 10 were very stable
thermally as well as air stable for extended periods of
time. On heating, 9 decomposed at 180 °C, while 10
decomposed at 125 °C.
1
at 10.82 ppm with J (Ag-P) coupling ) 470 Hz. For 3,
1
the doublet was centered at 9.70 ppm with J (Ag-P) )
361 Hz. Both of these coupling values are much larger
than the value for the parent compound 1 (1J (Ag-P) =
200 Hz).14 These results suggest that the silver-
phosphorus bonding in 2 and 3 is stronger compared
with 1.
Complex 9 was also synthesized from a reaction of
lithium diphenylphosphinocyclopentadienide, triphen-
ylphosphine, and silver triflate in CH2Cl2 as the solvent.
Under these conditions, the product crystallized as a
solvate with 0.5 equiv of CH2Cl2, as determined by both
1H NMR and elemental analysis. As in the case of
complexes 6 and 7, definitive conclusions concerning the
bonding in these new organosilver compounds must
await the results of X-ray diffraction studies.
Several highly substituted cyclopentadienyl deriva-
tives of silver and copper have also been synthesized
and characterized. Compounds 11 and 12 were prepared
at -78 and -10 °C, respectively, from reactions of
sodium pentaphenylcyclopentadienide and [Cl(PEt3)M]4
(where M ) Ag or Cu) in THF. After allowing the
reaction mixture to warm to room temperature, removal
of the solvent and subsequent extraction and crystal-
lization from diethyl ether produced 11and 12 in yields
of 56% and 44%, respectively. Compounds 11 and 12
had decomposition points of ca. 40 and 116 °C, respec-
tively, and 11 was both thermally and air sensitive. The
related compound Cu(η5-C5Ph5)(PPh3) was found to be
stable in air for at least several days.13 In contrast,
attempts to prepare (η5-C5Me5)Ag(PR3) (R ) Ph, Et) in
our laboratory have been unsuccessful. (η5-C5Me5)Cu-
For compounds 6 and 7, which both contain the
potentially chelating ligand 1,2-bis(diphenylphosphino)-
ethane instead of triphenylphosphine, only one phos-
phorus resonance was observed in each case. For 7, this
resonance appeared as a broad singlet at 20 °C, and
at -70 °C as a doublet centered at 4.21 ppm with
1J (Ag-P) ) 244 Hz. The 31P NMR solution spectrum
of 6 appeared as a broad doublet at 20 °C and as a
pair of sharp doublets at -40 °C, due to individual
1J (109Ag-P) and 1J (107Ag-P) couplings being ob-
served. The pattern was centered at 4.46 ppm, with
1
1J (109Ag-P) and J (107Ag-P) ) 266 and 231 Hz, respec-
tively. This represents the first example where the
individual isotope splittings have been resolved for a
cyclopentadienylsilver-phosphine derivative. The ratio
of the coupling values is 1.15, which exactly equals the
theoretical value.20
(17) Socal, S. M.; J acobson, R. A.; Verkade, J . G. Inorg. Chem. 1984,
23, 88.
(18) Muetterties, E. L.; Alegranti, C. W. J . Am. Chem. Soc. 1972,
94, 6386.
(19) Elyea, E. C.; Malito, J .; Nelson, J . H. Inorg. Chem. 1987, 26,
4294.
(20) Ebsworth, E. A. V.; Rankin, D. W. H.; Cradock, S. Structural
Methods in Inorganic Chemistry, 2nd ed.; Blackwell Scientific Publica-
tions: New York, 1992; p 97.

Cyclopentadienyl Derivatives of Ag and Cu
Organometallics, Vol. 19, No. 20, 2000 4063
pinocyclopentadienide,26 tetrakis[chloro(triethylphosphine)-
silver(I)],27 sodium pentaphenylcyclopentadienide,28 and tetra-
kis[chloro(triethylphosphine)copper(I)]29 were prepared by
literature procedures.
For compounds 9 and 10, binuclear complexes are
formed in which two nonequivalent phosphorus nuclei
are present. A silver atom is bonded to a cyclopentadi-
enyl ring, a phosphorus atom of a phosphine, and a
phosphorus atom of a second diphenylphosphinocyclo-
pentadienyl ring. The low-temperature solution 31P
NMR spectra and the 31P solid-state NMR spectra
exhibited similar patterns for each complex.
1H NMR spectra were obtained on either IBM 80 or 200
MHz spectrometers, or on Varian XL-200 or XL-300 spectrom-
eters, and are referenced to tetramethylsilane as an internal
standard. Solution 31P (taken at room temperature unless
otherwise noted) were obtained on either IBM 80 MHz, Varian
XL-300, or MSL-300 spectrometers and are referenced to 85%
H3PO4 in D2O as an external standard. Solid-state 31P NMR
spectra were obtained on an IBM 200 MHz spectrometer and
are referenced to CaHPO4. IR spectra were recorded on a
Perkin-Elmer 1310 spectrometer. Melting points were obtained
on a Mel-Temp apparatus and are uncorrected. Elemental
analyses were performed by the Microanalytical Laboratory,
University of Massachusetts, Amherst, MA.
(η-Acet ylcyclop en t a d ien yl)(t r ip h en ylp h osp h in e)sil-
ver (2). In a Schlenk flask were placed sodium acetylcyclo-
pentadienide (0.39 g, 3.0 mmol) and triphenylphosphine (0.79
g, 3.0 mmol). The flask was cooled to -10 °C, and then ca. 50
mL of DME was added. Silver triflate (0.79 g, 3.0 mmol) was
taken up in ca. 15 mL of DME and was slowly added to the
cooled reaction mixture. After stirring at -10 °C for 3 h, a
light-colored precipitate appeared. The reaction mixture was
filtered cold, and the off-white solid was washed several times
with cold DME. The solid was dried under vacuum for 24 h to
yield 0.83 g (58%) of (η-acetylcyclopentadienyl)(triphenyl-
phosphine)silver(I) (2).
The splitting patterns for 9 and 10 are explained by
two types of couplings. Each nonequivalent 31P nuclei
is split by a silver nuclei (1J ) and by the other 31P nuclei
(2J ). For 9, the pattern for the 31P solution spectrum at
-70 °C was centered at -6.62 ppm and exhibited
1
2
1J (Ag-P) ) 366 Hz, J (Ag-P) ) 422 Hz, and J (P-P)
) 130 Hz. The solution spectrum for 10 at -70 °C was
1
centered at -4.50 ppm and exhibited J (Ag-P) ) 439
Hz, J (Ag-P) ) 408 Hz, and 2J (P-P) ) 149 Hz. The
1
solid-state spectra for 9 and 10 also support the pro-
1
1
posed structures. For 9, J (Ag-P) ) 354 Hz, J (Ag-P)
402 Hz, and 2J (P-P) ) 134 Hz, and the pattern was
centered at -4.99 ppm. For 10, 1J (Ag-P) ) 413 Hz,
1J (Ag-P) ) 386 Hz, and 2J (P-P) ) 155 Hz, and the
pattern was centered at -10.50 ppm. The dimeric
complexes 9 and 10 exhibited enhanced air and thermal
stabilities, due to the presence of an additional phos-
phorus atom for back-bonding to silver and especially
by having chelated dimeric structures.
Compound 2 can also be synthesized under the same reac-
tion conditions using stoichiometric amounts of mono(tri-
phenylphosphine)silver(I) triflate and sodium acetylcyclopen-
tadienide. The yield of 2 was comparable to that of the above
Exp er im en ta l Section
All operations were performed under an argon atmosphere
using Schlenk and glovebox techniques. Argon was deoxygen-
ated by BASF catalyst and dried with P2O5 and molecular
sieves. Diethyl ether, 1,2-dimethoxyethane (DME), and tet-
rahydrofuran (THF) were predried over sodium wire and
distilled from sodium-potassium alloy under argon. Methylene
chloride was distilled under argon from calcium hydride.
Pentane and hexane were distilled from sodium-potassium
alloy under argon. All other solvents were used as com-
mercially obtained. CAMAG alumina was heated under vacuum
on a rotary evaporator to remove water and oxygen. The
alumina was then deactivated with 5% (by weight) argon-
sataurated water and stored under argon prior to use. Celite
was obtained from Fisher Scientific Co. and was used with no
prior treatment.
Ethyl acetate, methyl acetate, dimethyl carbonate, trieth-
ylphosphine, and chlorodiphenylphosphine were obtained from
Aldrich Chemical Co. Silver trifluoromethanesulfonate (tri-
flate), silver chloride, copper(I) chloride, copper(I) bromide,
triphenylphosphine, and 1,2-bis(diphenylphosphino)ethane
were also purchased from Aldrich. Cyclopentadiene dimer was
purchased from Aldrich and cracked in refluxing decalin to
give cyclopentadiene monomer, which was used immediately
after distillation. Sodium acetylcyclopentadienide,1,21 mono-
(triphenylphosphine)silver(I) trifluoromethanesulfonate,22 so-
dium carbomethoxycyclopentadienide,1,23 tetrakis[bromotriph-
enylphosphinecopper(I)],24 bis(triphenylphosphine)silver(I)
trifluoromethanesulfonate,22 bis(triphenylphosphine)copper(I)
trifluoromethanesulfonate,25 [1,2-bis(diphenylphosphino)ethane]-
silver(I) trifluoromethanesulfonate,22 lithium diphenylphos-
1
procedure. H NMR (CDCl3): δ 2.20 (3 H, s, CH3), 6.06 (2 H,
m, CpH3,4), 6.56 (2 H, m, CpH2,5), 7.10-7.48 (15 H, m, C6H5).
31P NMR (75% CH2Cl2/25% CDCl3, -70 °C): δ 10.82 (br d,
1J (Ag-P) ) 470 Hz). IR (νCO, CH2Cl2): 1643 cm-1. Anal. Calcd
for C25H22AgOP: C, 62.91; H, 4.65; Ag, 22.60. Found: C, 62.94;
H, 4.63; Ag, 21.90.
(η-Ca r b om et h oxycyclop en t a d ien yl)(t r ip h en ylp h os-
p h in e)silver (I) (3). In a Schlenk flask were placed sodium
carbomethoxycyclopentadienide (0.58 g, 4.0 mmol) and tri-
phenylphosphine (1.0 g, 4.0 mmol). The flask was cooled to
-10 °C, and ca. 50 mL of DME was added. Silver triflate (1.0
g, 4.0 mmol) was taken up in ca. 15 mL of DME and was then
slowly added to the reaction mixture. After stirring at -10 °C
for 2-3 h, the DME was removed under reduced pressure. The
residue was extracted with 25 mL of cold CH2Cl2 and then
filtered through a 1 cm alumina plug. The golden-yellow
solution was concentrated, and a small amount of diethyl ether
was added. The solution was crystallized at -20 °C to yield
1.12 g (57%) of (η-carbomethoxycyclopentadienyl)(triphen-
ylphosphine)silver(I) as an off-white solid. Compound 3 can
also be synthesized under the same reaction conditions using
stoichiometric amounts of mono(triphenylphosphine)silver(I)
triflate and sodium carbomethoxycyclopentadienide. The yield
was comparable to that of the above procedure. 1H NMR
(CDCl3): δ 3.72 (3 H, s, CH3), 6.24 (2 H, m, CpH3,4), 6.97 (2 H,
m, CpH2,5), 7.15-7.75 (15 H, m, C6H5). 31P NMR (75% CH2-
1
Cl2/25%CDCl3, -70 °C): δ 9.70 (br d, J (Ag-P) ) 361 Hz). IR
(νCO, CH2Cl2): 1639 cm-1. Anal. Calcd for C25H22AgO2P: C.
60.87; H, 4.50. Found: C, 60.55; H, 4.55.
(η-Acetylcyclop en ta d ien yl)(tr ip h en ylp h osp h in e)cop -
p er (I) (4). In a Schlenk flask were placed sodium acetylcy-
(21) Rogers, R. D.; Atwood, J . L.; Rausch, M. D.; Macomber, D. W.;
Hart, W. P. J . Organomet. Chem. 1982, 238, 79.
(22) Lettko, L.; Wood, J . S.; Rausch, M. D., Inorg. Chim. Acta,
submitted.
(23) Hart, W. P.; Shihua, D.; Rausch, M. D. J . Organomet. Chem.
1985, 282, 111.
(24) Costa, G.; Pellizer, G.; Rubessa, F. J . Inorg. Nucl. Chem. 1964,
26, 961.
(25) Dines, M. B. J . Inorg. Nucl, Chem. 1964, 26, 961.
(26) Mathey, F.; Lampin, J . P. J . Organomet. Chem. 1977, 128, 297.
(27) Churchill, M. R.; Donahue, J .; Rotella, F. J . Inorg. Chem. 1976,
15, 2752.
(28) Zhang, R.; Tsutsui, M.; Bergbreiter, D. E. J . Organomet. Chem.
1982, 109, 229.
(29) Churchill, M. R.; DeBoer, B. G.; Mendak, S. S. Inorg. Chem.
1975, 14, 2041.

4064 Organometallics, Vol. 19, No. 20, 2000
Lettko and Rausch
clopentadienide (0.49 g, 3.8 mmol) and tetrakis[bromotriph-
enylphosphinecopper] (1.0 g, 0.62 mmol). The flask was cooled
to -78 °C, and 35 mL of THF was added via a syringe. The
reaction mixture was stirred at -78 °C for 2 h before warming
to 25 °C and then stirred for an additional 2 h. The THF was
removed under reduced pressure, and the residue was ex-
tracted with ca. 45 mL of hexane. After filtration through
Celite, the light yellow solution was kept at -20 °C to form
0.42 g (39%) of (η-acetylcyclopentadienyl)(triphenylphosphine)-
copper(I). An analytically pure sample was obtained by an
additional crystallization from hexane at -20 °C to give small
off-white crystals. 1H NMR (CDCl3): δ 2.34 (3 H, s, CH3), 6.09
(2 H, m, CpH3,4), 6.67 (2 H, m, CpH2,5), 7.25-7.46 (15 H, m,
C6H5). 31P NMR (75% CH2Cl2/25% CDCl3, -70 °C): δ 7.78 (br
s). IR (νCO, CH2Cl2): 1622 cm-1. Anal. Calcd for C25H22CuOP:
C, 69.35; H, 5.12. Found: C, 68,79; H, 5.28.
(η-Ca r b om et h oxycyclop en t a d ien yl)(t r ip h en ylp h os-
p h in e)cop p er (I) (5). In a Schlenk flask were placed sodium
carbomethoxycyclopentadienide (0.70 g, 4.8 mmol) and tet-
rakis[bromotriphenylphosphinecopper] (1.0 g, 6.2 mmol). The
flask was cooled to -78 °C, and ca. 40 mL of THF was added
via a syringe. The reaction mixture was stirred at -78 °C for
2 h before warming slowly to 25 °C and then stirred for an
additional 2 h. The THF was removed under reduced pressure,
and the residue was extracted with ca. 40 mL of diethyl ether.
After filtration through Celite, the light orange solution was
kept at -20 °C to form 0.72 g (64%) of (η-carbomethoxycyclo-
pentadienyl)(triphenylphosphine)copper(I). An analytically pure
sample was obtained by several crystallizations from di-
ethyl ether at -20 °C to give small white crystals. 1H NMR
(CDCl3): δ 3.72 (3 H, s, CH3), 6.02 (2 H, m, CpH3,4), 6.67 (2 H,
m, CpH2,5), 7.20-7.54 (15 H, m, C6H5). 31P NMR (75%
CH2Cl2/25% CDCl3, -70 °C): δ 23.83 (br s). IR (νCO, CH2Cl2):
1678 cm-1. Anal. Calcd for C25H22CuO2P: C, 66.88; H, 4.94.
Found: C, 66.92; H, 5.04.
concentrated, and a small amount of diethyl ether was added.
The solution was allowed to crystallize at -78 °C to yield 0.76
g (55%) of (η-carbomethoxycyclopentadienyl)[(1,2-bis(diphen-
ylphosphino)ethane]silver(I) as an off-white solid. Compound
7 can also be synthesized under the same reaction conditions,
using stoichiometric amounts of [1,2-bis(diphenylphospino)-
ethane]silver(I) triflate and sodium carbomethoxycyclopenta-
dienide. The yield was comparable to that of the above
procedure. 1H NMR (CDCl3): δ 2.14-2.49 (4 H, br m, CH2-
CH2), 3.65 (3 H, s, CH3), 6.25 (2 H, m, CpH3,4), 6.94 (2 H, m,
CpH2,5), 7.10-7.92 (20 H, m, C6H5). 31P NMR (75% CH2Cl2/
1
25% CDCl3, -70 °C): δ 4.21 (d, J (Ag-P) ) 2.44 Hz). IR (νCO
,
CH2Cl2): 1643 cm-1. Anal. Calcd for C33H31AgO2P2: C, 62.97;
H, 4.96, Ag, 17.14. Found: C, 63.16; H, 5.16; Ag, 16.96.
[(η-Dip h e n ylp h osp h in ocyclop e n t a d ie n yl)(t r ip h e n -
ylp h osp h in e)silver (I)]2 (9). In a Schlenk flask were placed
silver chloride (0.72 g, 5.0 mmol) and triphenylphosphine (1.31
g, 5.0 mmol). Approximately 100 mL of toluene was added,
and the combined solids were heated at reflux for 18 h. The
opaque solution was then cooled to -78 °C, and a suspension
of lithium diphenylphosphinocyclopentadienide (1.30 g, 5.0
mmol) in 25 mL of toluene was slowly added. The reaction was
stirred at -78 °C for 4 h and was then gradually warmed to
25 °C and stirred for an additional hour. The reaction mixture
was filtered through Celite to yield a light yellow solution. The
solution was cooled to -20 °C to give 1.52 g (49%) of
[(η-diphenylphosphinocyclopentadienyl)(triphenylphosphine)-
silver(I)]2 as light yellow crystals.
Compound 9 can be synthesized under the same reaction
conditions using separate stoichiometric amounts of mono-
(triphenylphosphine)silver(I) triflate and lithium diphenylphos-
phinocyclopentadienide. The yield was comparable to that of
1
the above procedure. H NMR (CDCl3): δ 6.l9-6.39 (4 H, br
m, C5H4), 6.91-7.45 (25 H, m, C6H5). 31P NMR (75% CH2Cl2/
25% CDCl3, -70 °C): δ -6.62 (m, 1J (Ag-P) ) 366 Hz,
1J (Ag-P) ) 422 Hz, 2J (P-P) ) 130 Hz). Solid-state 31P NMR:
δ -4.99 (m, 1J (Ag-P) ) 354 Hz, 1J (Ag-P) ) 402 Hz, 2J (P-P)
) 134 Hz. Anal. Calcd for C70H58Ag2P4: C, 67.86; H, 4.72.
Found: C, 68.16; H, 4.85.
(η-Acetylcyclop en ta d ien yl)[1,2-bis(d ip h en ylp h osp h i-
n o)eth a n e]silver (I) (6). In a Schlenk flask were placed
sodium acetylcyclopentadienide (0.59 g, 4.5 mmol) and 1,2-
bis(diphenylphosphino)ethane (1.8 g, 4.5 mmol). The flask was
cooled to 0 °C, and ca. 90 mL of DME was added. Silver triflate
(1.16 g, 4.5 mmol) was taken up in ca. 25 mL of DME and was
then slowly added to the cold reaction mixture. The reaction
was stirred at 0 °C for 2 h, and the DME was removed under
reduced pressure. The residue was extracted with ca. 45 mL
of cold CH2Cl2. The CH2Cl2 solution was filtered through a 2
cm alumina plug and concentrated, and then a small amount
of diethyl ether was added. The solution was allowed to
crystallize at -78 °C to yield 2.0 g (72%) of (η-acetylcyclopen-
tadienyl)[1,2-bis(diphenylphosphino)ethane]silver(I) as an off-
white solid. Compound 6 can also be synthesized under the
same reaction conditions, using stoichiometric amounts of [1,2-
bis(diphenylphosphino)ethane]silver(I) triflate and sodium
acetylcyclopentadienide. The yield was comparable with that
[(η-Dip h e n ylp h osp h in ocyclop e n t a d ie n yl)(t r ip h e n -
ylp h osp h in e)silver (I)]2‚0.5CH2Cl2. In a Schlenk flask were
placed lithium diphenylphosphinocyclopentadienide (0.79 g,
3.0 mmol) and triphenylphosphine (0.79 g, 3.0 mmol). The flask
was cooled to -78 °C, and ca. 65 mL of CH2Cl2 was added.
Silver triflate (0.78 g, 3.0 mmol) suspended in ca. 15 mL of
CH2Cl2 was then slowly added to the cold reaction mixture.
The reaction was stirred at -78 °C for 3 h and then gradually
warmed to 0 °C. The reaction mixture was filtered over Celite
to yield a yellow solution. The solution was cooled to -20 °C
to yield 0.85 g (43%) of [(η-diphenylphosphinocyclopentadi-
enyl)(triphenylphosphine)silver(I)]2‚0.5CH2Cl2 as light yel-
low crystals. 1H NMR (CDCl3): δ 5.30 (1 H, s, 0.5 CH2Cl2),
6.33-6.45 (4 H, br m, C5H4), 7.09-7.43 (25 H, m, C6H5). Anal.
Calcd for C71H60Ag2Cl2P4: C, 64.42; H; 4.56. Found: C, 64.87;
H, 4.54.
[(η-Dip h e n ylp h osp h in ocyclop e n t a d ie n yl)(t r ie t h yl-
p h osp h in e)silver (I)]2 (10). In a Schlenk flask were placed
silver chloride (0.72 g, 5.0 mmol) and triethylphosphine (0.74
mL, 5.0 mmol). Approximately 80 mL of toluene was added,
and the reaction mixture was heated at reflux for 2 h. The
opaque solution was cooled to -78 °C, and a suspension of
lithium diphenylphosphinocyclopentadienide (1.30 g, 5.0 mmol)
in ca. 20 mL of toluene was slowly added. The opaque solution
was stirred at -78 °C for 4 h before gradually being warmed
to 25 °C. As the reaction mixture warmed, it turned yellow.
The mixture was stirred at 25 °C for an additional 30 min and
was then filtered over Celite. The light yellow solution was
cooled at -20 °C to yield 0.86 g (36%) of [(η-diphenylphosphi-
nocyclopentadienyl)(triethylphosphine)silver(I)]2 as colorless
crystals. 1H NMR (CDCl3): δ 0.64-1.59 (15 H, m, C2H5), 6.35-
6.48 (4 H, br m, C5H4), 7.10-7.61 (15 H, m, C6H5). 31P NMR
1
of the above procedure. H NMR (CDCl3): δ 2.17-2.40 (7 H,
m, CH3 and CH2CH2), 6.23 (2 H, m, CpH3,4), 6.86 (2 H, m,
CpH2,5), 7.20-7.51 (20 H, m, C6H5). 31P NMR (75% CH2Cl2/
25% CDCl3, -70 °C): δ 4.46 (dd, 1J (109Ag-P) ) 266 Hz,
1J (107Ag-P) ) 231 Hz. IR (νCO, CH2Cl2): 1642 cm-1. Anal.
Calcd for C33H31AgOP2: C, 64.61; H, 5.09. Found: C, 64.13;
H, 5.01.
(η-Ca r b om et h oxycyclop en t a d ien yl)[1,2-b is(d ip h en -
ylp h osp h in o)eth a n esilver (I) (7). In a Schlenk flask were
placed sodium carbomethoxycyclopentadienide (0.32 g, 2.2
mmol) and 1,2-bis(diphenylphosphino)ethane (0.88 g, 2.2
mmol). The flask was cooled to 0 °C, and ca. 50 mL of DME
was added. Silver triflate (0.57 g, 2.2 mmol) was taken up in
ca. 15 mL of DME and was then slowly added to the cold
reaction mixture. The reaction was stirred at 0 °C for 2 h, and
then the DME was removed under reduced pressure. The
residue was extracted with ca. 20 mL of cold CH2Cl2. The
CH2Cl2 solution was filtered through a 1 cm alumina plug and

Cyclopentadienyl Derivatives of Ag and Cu
Organometallics, Vol. 19, No. 20, 2000 4065
(75% CH2Cl2/25% CDCl3, -70 °C): δ -4.50 (m, 1J (Ag-P) )
(br s). Anal. Calcd for C41H40AgP: C, 73.32; H, 6.00. Found:
C, 74.02; H, 6.85.
(η-P en ta p h en ylcyclop en ta d ien yl)(tr ieth ylp h osp h in e)-
1
2
439 Hz, J (Ag-P) ) 408 Hz, J (P-P) ) 149 Hz). Solid-state
1
1
31P NMR: δ -10.50 (m, J (Ag-P) ) 413 Hz, J (Ag-P) ) 386
Hz, 2J (P-P) ) 155 Hz. Anal. Calcd for C46H58Ag2P4: C, 58.12;
H, 6.15. Found: 58.02; H, 6.03.
cop p er (I) (12). In
a Schlenk flask were placed sodium
pentaphenylcyclopentadienide (0.95 g, 2.0 mmol) and tetrakis-
[chloro(triethylphosphine)copper] (0.43 g, 0.5 mmol). The flask
was cooled to -10 °C, and ca. 40 mL of THF was added. The
reaction mixture was initially pink, but within 15 min it turned
yellow. After stirring at -10 °C for 2 h, the reaction mixture
was allowed to gradually warm to 25 °C and was stirred for
an additional 2 h. The THF was removed under reduced pres-
sure and the residue was extracted with ca. 25 mL of diethyl
ether. After filtration through Celite, the yellow solution was
cooled to -20 °C, yielding 0.55 g (44%) of (η5-pentaphenylcy-
clopentadienyl)(triethylphosphine)copper(I) as small white
crystals, mp 116 °C dec. 1H NMR (CDCl3): δ 0.87-1.83 (15
H, m, CH2CH3), 6.88-7.08 (25 H, m, C6H5). 31P NMR (CH2-
Cl2/D2O): δ 11.68 (br s). Anal. Calcd for C41H40CuP: C, 78.50;
H, 6.43. Found: C, 77.98; H, 6.45.
(η-P en ta p h en ylcyclop en ta d ien yl)(tr ieth ylp h osp h in e)-
silver (I) (11). In an argon-flushed 100 mL Schlenk flask were
placed sodium pentaphenylcyclopentadienide (1.0 g, 2.1 mmol)
and tetrakis[chloro(triethylphosphine)silver] (0.55 g, 0.52 mmol).
The flask was cooled to -78 °C, and ca.75 mL of THF was
added. The golden-brown reaction mixture was stirred at -78
°C for 3 h before gradual warming to 0 °C. The THF was
removed under reduced pressure, and the residue was ex-
tracted with ca. 50 mL of diethyl ether. The purple solution
was cooled to -20 °C, yielding 0.79 g (56%) of (η-pentaphen-
ylcyclopentadienyl)(triethylphosphine)silver(I) as crystal-
line purple solid.30 1H NMR (CDCl3): δ 0.92-1.80 (15 H, m,
CH2CH3), 6.49-7.55 (25 H, m, C6H5). 31P NMR (CDCl3): δ 0.53
(30) Compound 11 was both thermally and air sensitive, and
attempts to further purify 11 to obtain an analytically pure sample
were unsuccessful.
OM000618H