Reactions of tungsten phosphonium carbyne complexes with aryloxide nucleophiles to form aryloxycarbyne and η2-ketenyl complexes

Article abstract of DOI:10.1016/S0020-1693(01)00773-3

Tungsten phosphoranylideneketene complexes of the type Tp′(CO)(p-OC₆H₄R)W(η²-(C,C) -O=CC-PR′₂Ph) (R=NO₂, R′=Me (6a); R=NO₂, R′=Ph (6b); R=CN, R′=Me (7a); R=CN, R′=Ph (7b); R=Cl, R′=Ph (8b)) have been synthesized from phosphonium carbyne precursors in a reaction that reflects coupling of carbonyl and carbyne ligands. In addition to these products, aryloxycarbyne complexes Tp′(CO)₂W≡CO(p-C₆H₄NO ₂) (9a), Tp′(CO)₂W≡CO(p-C₆H₄CN) (9b), and Tp′(CO)₂W≡CO(p-C₆H₄Cl) (9c)) have been prepared via substitution of the phosphonium carbyne phosphine with an aryloxide nucleophile. The product ratio of substitution at the carbyne carbon to carbonyl-carbyne coupling can be tuned by variation of the aryloxide para-substituent. Aryloxy carbyne complexes are the favored products with stronger nucleophiles, while weaker nucleophiles result in a mixture of aryloxy carbyne complexes and η²-ketenyl coupled complexes. Formation of η²-ketenyl complexes is favored for the least nucleophilic aryloxides. Ketenyl complexes 6a and 6b were methylated at the ketenyl oxygen to form cationic alkyne complexes [Tp′(CO)(p-OC₆H₄NO₂)W(η ²-(C,C)-CH₃OC≡CPR₂Ph)][OTf] (R=Me (10a), R=Ph (10b)). The structures of η²-ketenyl complexes 6a and 7b and the structure of cationic alkyne complex 10a were determined by X-ray crystallography.

Full text of DOI:10.1016/S0020-1693(01)00773-3

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Inorganica Chimica Acta 330 (2002) 161–172
Reactions of tungsten phosphonium carbyne complexes with
aryloxide nucleophiles to form aryloxycarbyne and h2-ketenyl
complexes
Kenneth C. Stone, Greg M. Jamison, Peter S. White, Joseph L. Templeton *
Department of Chemistry, Uni6ersity of North Carolina, Chapel Hill, NC 27599-3290, USA
Received 10 August 2001; accepted 31 October 2001
Dedicated to the memory of Professor Luigi Venanzi
Abstract
Tungsten phosphoranylideneketene complexes of the type Tp%(CO)(p-OC6H4R)W(h2-(C,C)ꢀOꢁCCꢀPR2%Ph) (R=NO2, R%=Me
(6a); R=NO2, R%=Ph (6b); R=CN, R%=Me (7a); R=CN, R%=Ph (7b); R=Cl, R%=Ph (8b)) have been synthesized from
phosphonium carbyne precursors in a reaction that reflects coupling of carbonyl and carbyne ligands. In addition to these
products, aryloxycarbyne complexes Tp%(CO)2WꢂCO(p-C6H4NO2) (9a), Tp%(CO)2WꢂCO(p-C6H4CN) (9b), and Tp%(CO)2WꢂCO(p-
C6H4Cl) (9c)) have been prepared via substitution of the phosphonium carbyne phosphine with an aryloxide nucleophile. The
product ratio of substitution at the carbyne carbon to carbonyl–carbyne coupling can be tuned by variation of the aryloxide
para-substituent. Aryloxy carbyne complexes are the favored products with stronger nucleophiles, while weaker nucleophiles result
in a mixture of aryloxy carbyne complexes and h2-ketenyl coupled complexes. Formation of h2-ketenyl complexes is favored for
the least nucleophilic aryloxides. Ketenyl complexes 6a and 6b were methylated at the ketenyl oxygen to form cationic alkyne
complexes [Tp%(CO)(p-OC6H4NO2)W(h2-(C,C)ꢀCH3OCꢂCPR2Ph)][OTf] (R=Me (10a), R=Ph (10b)). The structures of h2-
ketenyl complexes 6a and 7b and the structure of cationic alkyne complex 10a were determined by X-ray crystallography. © 2002
Elsevier Science B.V. All rights reserved.
Keywords: Phosphoranylideneketene; Tungsten; Phosphonium carbyne; Ligand coupling; Phosphonium carbyne complexes; Aryloxycarbyne
1. Introduction
both metal and ligand based orbitals [4]. As a result of
this orbital energy proximity, strong nucleophiles can
access both carbon-centered and metal-centered or-
bitals. Weak nucleophiles tend to favor attack at the
vacant orbital centered on the metal [5].
Fischer founded a new class of complexes containing
transition metal–carbon triple bonds in 1973 [1]. Reac-
tivity patterns of carbyne complexes have been thor-
oughly reviewed by Kim and Angelici [2]. Cationic
carbyne complexes generally react with nucleophiles at
the carbyne carbon, while neutral carbyne complexes
can react at either the metal center or the carbyne
carbon. The reactivity of cationic carbyne complexes is
compatible with the predictions of frontier molecular
orbital theory. Molecular orbital calculations identify
the LUMO of cationic carbyne complexes as a metal–
carbon p* orbital [3]. Similar molecular orbital calcula-
tions on neutral carbyne complexes reveal that the
vacant metal–carbon p* orbital is close in energy to
Angelici has reported an exception to the general
reactivity pattern of cationic carbyne complexes. Treat-
ment of the cationic carbyne complex [(HC(pz)3)-
(CO)2WꢂCꢀSMe][PF6] (pz=pyrazolyl) (1) with phos-
phine nucleophiles (PR3) provides h2-ketenyl products,
(HC(pz)3)(CO)(PR3)W(h2-(C,C)ꢀOꢁCCꢀSMe)
(2),
reflecting net nucleophilic addition to tungsten rather
than nucleophilic attack at Ca (Scheme 1) [6]. The
neutral analog of 2, (HB(pz)3)(CO)2WꢂCꢀSMe (3), un-
dergoes an analogous carbyne–carbonyl coupling reac-
tion when treated with phosphines [7].
Cationic phosphonium carbyne complexes, [Tp%-
(CO)2WꢂCPR3][PF6] (5), have been synthesized by
* Corresponding author. Fax: +1-919-962 2388.
0020-1693/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(01)00773-3

162
K.C. Stone et al. / Inorganica Chimica Acta 330 (2002) 161–172
Scheme 1.
Scheme 2.
Scheme 3.
treating Tp%(CO)2WꢂCCl (4) [8] (Tp%=hydridotris(3,5-
dimethylpyrazolyl)borate) with PR3 in the presence of
KPF6 (Scheme 2) [9]. These phosphonium carbyne
complexes undergo nucleophilic displacement of phos-
phine at Ca with anionic nucleophiles to provide neu-
tral Tp%(CO)2WꢂCꢀR (R=H, aryloxide) [9–11]
compounds in high yields. Treatment of [Tp%(CO)2-
WꢂCPMe2Ph][PF6] (5a) with the electron-rich aryloxide
[p-OC6H4OCH3]− provides exclusively the aryloxycar-
byne product Tp%(CO)2WꢂCO(p-C6H4OMe). Here we
report that this same cationic phosphonium carbyne
reagent, 5a, forms an h2-ketenyl complex when treated
with an electron-poor aryloxide nucleophile like [p-
OC6H4NO2]−.
[Tp%(CO)(p-OC6H4NO2)W(h2-(C,C)ꢀCH3OCꢂCPR2Ph)]-
[OTf] (R=Me (10a), R=Ph (10b)). Data for the
new carbyne complexes Tp%(CO)2WꢂCO(p-C6H4NO2)
(9a), Tp%(CO)2WꢂCO(p-C6H4Cl) (9c), and Tp%(CO)2-
WꢂCPh (11) are also included. The structures
The ratio of aryloxycarbyne product to h2-phospho-
ranylideneketene (h2-ketenyl) product obtained by
treating phosphonium carbyne complexes with different
para-substituted aryloxide nucleophiles has now been
probed (Scheme 3). Variation of the electron donating
and electron withdrawing properties of para-sub-
stituents on the aryloxide reagent alters the electronic
properties of the nucleophile and influences the product
distribution.
Tungsten phosphoranylideneketene complexes of the
type Tp%(CO)(p-OC6H4R)W(h2-(C,C)ꢀOꢁCCꢀPR%Ph)
2
(R=NO2, R%=Me (6a); R=NO2, R%=Ph (6b); R=
CN, R%=Me (7a); R=CN, R%=Ph (7b); R=Cl, R%=
Ph (8b)) have been synthesized (Fig. 1). Complexes 6a
and 6b were methylated to form alkyne complexes
Fig. 1.

K.C. Stone et al. / Inorganica Chimica Acta 330 (2002) 161–172
163
of 6a, 7b, and 10a have been determined by X-ray
crystallography.
2.06, 1.56 (s, 3:3:3:3:3:3H, Tp% CCH3), 1.68, 1.28 (d,
3:3H 2JP–H=14 Hz, CPMe2Ph). 13C{1H} NMR
3
1
(CD2Cl2, l): 229.0 (d, JP–C=3 Hz, JW–C=181 Hz,
WCO), 201.2 (s, OCCPMe2Ph), 177.2, 151.8, 125.9,
125.0 (s, p-C6H4NO2), 154.6, 153.6, 152.0, 146.3, 145.2,
144.6 (s, 1:1:1:1:1:1C, Tp% CCH3), 133.2, 130.4, 129.7,
2. Experimental
1
1
Reactions were carried out under an inert atmo-
sphere of nitrogen or argon using standard Schlenk
techniques. Tetrahydrofuran (THF) was dried by distil-
lation from sodium and benzophenone. Other solvents
were dried with activated alumina [12]. The complexes
[Tp%(CO)2WꢂCPMe2Ph][PF6] (5a) and [Tp%(CO)2Wꢂ
CPPh3][PF6] (5b) were prepared according to literature
methods [9]. The potassium salts of the aryloxides were
synthesized in dry THF in one of three ways: (i) by
reaction of the alcohol with solid potassium, (ii) by
deprotonation of the alcohol with potassium hydride in
the presence of 18-crown-6, or (iii) by deprotonation of
the alcohol with potassium tert-butoxide. Other
reagents were used as obtained from commercial
sources.
IR spectra were obtained on an ASI React IR 1000
spectrometer. NMR spectra were obtained on a Bruker
Avance 400 or a Bruker AMX-300 spectrometer. Ele-
mental analyses were performed by Atlantic Microlab,
Inc., Norcross, GA. Products were isolated analytically
pure after recrystallization or chromatography unless
otherwise stated.
125.6 (d, CPMe2Ph), 117.6 (d, JP–C=88 Hz, JW–C=
53 Hz, OCCPMe2Ph), 107.9, 107.5, 107.4 (s, 1:1:1C,
Tp% CH), 16.2, 15.4, 14.2, 13.0, 12.9, 12.5 (s,
1
1:1:1:1:1:1C, Tp% CCH3), 11.5, 10.1 (d, JP–C=60 Hz,
PMe2Ph). 31P NMR (CD2Cl2, l): 15.5. Anal. Found: C,
43.15; H, 4.24; N, 10.73. Calc. for C32H37BN7O5PW·
CH2Cl2: C, 43.54; H, 4.32; N, 10.77%.
2.2. Tp%(CO)(p-OC6H4NO2)W(p2-(C,C)ꢀOCCPPh3)
(6b)
A solution of 0.093 g K[p-OC6H4NO2] in 30 ml of
THF and a solution of 0.50 g 5b in 30 ml of THF were
prepared and the latter was cooled to −78 °C. The
yellow aryloxide solution was added drop-wise into the
cooled solution causing a color change from purple to
red. After 10 min there was no further color change,
and the solution was allowed to warm to ambient
temperature. After stirring for 4 h, little product was
observed by IR (wCO 1872 cm−1) and the reaction
solution was refluxed overnight before the dark yel-
low–green solution was stripped in vacuo. Chromatog-
raphy (alumina, THF) afforded a single green band.
The solid remaining after rotary evaporation was an
amorphous brown solid, but recrystallization from
dichloromethane and hexanes afforded green needles.
The needles were washed with hexanes and dried in
vacuo. Yield: 68%. Complexes 7a and 7b were prepared
by a similar method. 6b: IR (KBr, cm−1): wCO 1872,
Spectroscopic data for aryloxide substituted carbyne
complexes 9a–f are in agreement with data for other
aryloxycarbyne complexes [9].
2.1. Synthesis of
Tp%(CO)(p-OC6H4NO2)W(p2-(C,C)ꢀOCCPMe2Ph) (6a)
1
An oven-dried Schlenk flask was charged with an
excess of KH in mineral oil, which was washed with
THF. The KH was suspended in 75 ml THF, and 0.40
g (2.90 mmol) of HO(p-C6H4NO2) was added, generat-
ing immediate gas evolution. Addition of 0.75 g (2.90
mmol) of 18-crown-6 to the bright yellow solution
initiated further gas evolution. The mixture was al-
lowed to stir at 25 °C for 30 min, then filtered via
cannula to a Schlenk flask containing a cooled (−78
1710. H NMR (CD2Cl2, l): 8.16, 6.90 (AA%BB%, 2:2H,
p-C6H4NO2), 7.56, 7.34, 7.24 (m, 3:6:6H, CPPh3), 5.79,
5.71, 5.01 (s, 1:1:1H, Tp%CH), 2.58, 2.34, 2.31, 2.25,
1.58, 1.51 (s, 3:3:3:3:3:3H, Tp%CH3). 13C{1H} NMR
3
(CD2Cl2, l): 229.4 (d, JP–C=3 Hz, WCO), 203.7 (d,
2JP–C=3 Hz, CCO), 177.4, 139.3, 126.1, 120.0 (s,
1:1:2:2C, p-C6H4NO2), 154.1, 153.6, 151.6, 146.2, 144.9,
143.7 (s, 1:1:1:1:1:1C, Tp%CCH3), 133.4, 133.2, 129.3,
123.8 (d, 6:3:6:3C, CPPh3), 119.5 (d, 1JP–C=85 Hz,
CCPPh3), 107.7, 107.5 (s, 2:1C, Tp%CH) 15.49, 15.48,
14.2, 13.0, 12.8, 12.5 (s, 1:1:1:1:1:1C, Tp%CH3). 31P{1H}
NMR (CD2Cl2, l): 20.7 (s, CPPh3). Anal. Found: C,
52.96; H, 4.42; N, 10.19. Calc. for C42H41BN7O5PW: C,
53.13; H, 4.35; N, 10.33%.
°C) solution of 2.00
g
(2.40 mmol) of
[Tp%(CO)2WꢂCꢀPMe2Ph][PF6] in 150 ml THF. After
warming to room temperature, the solution turned dark
green, and a new infrared band appeared at 1875 cm−1
.
The solvent was removed in vacuo and the residue was
chromatographed (alumina; eluted first with hexanes,
then changed to 2:1 THF:hexanes). Dark green crystals
of 6a (0.62 g, 31% yield) were isolated following recrys-
tallization from CH2Cl2/MeOH at −35 °C. IR (THF,
2.3. Tp%(CO)(p-OC6H4CN)W(p2-(C,C)ꢀOCCPMe2Ph)
(7a)
1
cm−1): wCO 1875, 1720. H NMR (CD2Cl2, l): 7.42 (m,
Yield: 25%. IR (KBr, cm−1): wCN 2212, wCO 1849,
1722. 1H NMR (CD2Cl2, l): 7.55, 7.43, 7.31 (m,
1:2:2H, PMe2Ph), 7.44, 6.68 (AA%BB%, 2:2H, p-
5H, CPMe2Ph), 7.26 (AA%BB%, 4H, p-C6H4NO2), 5.84,
5.81, 5.71 (s, 1:1:1H, Tp% CH), 2.48, 2.45, 2.31, 2.26,

164
K.C. Stone et al. / Inorganica Chimica Acta 330 (2002) 161–172
C6H4CN), 5.83, 5.79, 5.71 (s, 1:1:1H, Tp%CH), 2.47,
2.45, 2.31, 2.25, 2.06, 1.57 (s, 3:3:3:3:3:3H, Tp%CH3),
nitrile). Recrystallization from CH2Cl2:hexanes pro-
duced a mixture of dark green rods and green
starbursts (30 mg). The two types of crystals consisted
of the same material by IR and NMR. Proton NMR
showed a 10:1 mixture of 8b and an uncharacterized
ketenyl product that was not separable. Yield: 12%. IR
2
1.66, 1.26 (d, 3:3H, JP–H=13 Hz, CPMe2Ph). 13C{1H}
NMR (CD2Cl2, l): 229.4 (d, 3JP–C=3 Hz, WCO),
201.1 (s, CCO), 174.7, 133.6, 121.0, 100.1 (s, 1:2:2:1C,
p-C6H4CN), 154.5, 153.6, 152.0, 146.2, 145.1, 144.5 (s,
1:1:1:1:1:1C, Tp%CCH3), 133.1, 130.4, 129.7, 125.7 (d,
1:2:2:1C, CPMe2Ph), 121.0 (s, p-C6H4CN), 115.0 (d,
1JP–C=89 Hz, OCCPMe2Ph), 107.8, 107.5, 107.3 (s,
1:1:1C, Tp%CH), 16.2, 15.4, 14.1, 12.93, 12.87, 12.5 (s,
1:1:1:1:1:1C, Tp%CH3), 11.6, 10.1 (d, 1JP–C=61 Hz,
CPMe2Ph). 31P{1H} NMR (CD2Cl2, l): 15.0 (s,
CPMe2Ph). Anal. Found: C, 46.52; H, 4.54; N, 11.19.
Calc. for C33H37BN7O3PW·CH2Cl2: C, 46.59; H, 4.36;
N, 10.87%.
1
(KBr, cm−1): wCO 1861, 1706. H NMR (CD2Cl2, l):
7.54, 7.33, 7.24 (m, 3:6:6H, CPPh3), 7.19, 6.82 (AA%BB%,
2:2H, p-C6H4Cl), 5.76, 5.68, 4.99 (s, 1:1:1H, Tp%CH),
2.55, 2.32, 2.29, 2.25, 1.62, 1.54 (s, 3:3:3:3:3:3H,
3
Tp%CH3). 13C{1H} NMR (CD2Cl2, l): 230.7 (d, JP–
2
C=3 Hz, WCO), 203.0 (d, JP–C=2 Hz, OCCPPh3),
170.4, 128.8, 122.9, 121.4 (s, 1:2:1:2C, p-C6H4Cl), 154.0,
153.7, 151.7, 145.8, 144.6, 143.5 (s, 1:1:1:1:1:1C,
Tp%CCH3), 133.4, 133.0, 129.2, 124.5 (d, 6:3:6:3C,
CPPh3), 110.7 (d, 1JP–C=85 Hz, OCCPPh3), 107.6,
107.5, 107.4 (s, 1:1:1C, Tp%CH), 15.50, 15.47, 14.2, 13.0,
12.8, 12.5 (s, 1:1:1:1:1:1C, Tp%CH3). 31P{1H} NMR
(CD2Cl2, l): 19.6 (s, CPPh3).
2.4. Tp%(CO)(p-OC6H4CN)W(p2-(C,C)ꢀOCCPPh3)
(7b)
Yield: 52%. IR (KBr, cm−1): wCN 2216, wCO 1868,
1714. 1H NMR (CD2Cl2, l): 7.56, 7.34, 7.23 (m,
3:6:6H, CPPh3), 7.54, 6.93 (AA%BB%, 2:2H, p-C6H4CN),
5.78, 5.71, 5.01 (s, 1:1:1H, Tp%CH), 2.57, 2.34, 2.30,
2.23, 1.58, 1.52 (s, 3:3:3:3:3:3H, Tp%CH3). 13C{1H}
NMR (CD2Cl2, l): 229.8 (d, 3JP–C=3 Hz, WCO),
2.6. Tp%(CO)2WꢂCO(p-C6H4NO2) (9a)
In the manner described above (see 6a), excess KH,
0.83 g (6.0 mmol) of HO(p-C6H4NO2) and 1.60 g (6.0
mmol) of 18-crown-6 were used to generate a THF
solution of the phenoxide, which was cannulated into a
2
203.5 (d, JP–C=3 Hz, OCCPPh3), 175.0, 133.9, 121.0,
100.1 (s, 1:2:2:1C, p-C6H4CN), 154.0, 153.6, 151.6,
146.1, 144.8, 143.6 (s, 1:1:1:1:1:1C, Tp%CCH3), 133.3,
133.2, 129.2, 123.9 (d, 6:3:6:3C, CPPh3), 121.1 (s, p-
Schlenk flask containing 3.20
g
(5.5 mmol)
Tp%(CO)2WꢂCꢀCl in 200 ml of acetonitrile. Refluxing
the mixture for 7 days affected slow conversion of the
chlorocarbyne complex to aryloxycarbyne complex 9a;
infrared intensities diminished after prolonged reflux,
and the reaction was stopped at 50% conversion (by
IR). Solvent removal and alumina chromatography
(first with hexanes, then changed to 2:1 hexanes:THF)
permitted separation of starting material (first yellow
band) from 0.50 g (13% yield) of 9a, which was isolated
as a light-sensitive yellow powder after solvent removal.
1
C6H4CN), 117.0 (d, JP–C=84 Hz, OCCPPh3), 107.64,
107.63, 107.5 (s, 1:1:1C, Tp%CH), 15.5, 14.2, 13.0, 12.8,
12.5 (s, 2:1:1:1:1C, Tp%CH3). 31P{1H} NMR (CD2Cl2,
l): 19.9 (s, CPPh3). Anal. Found: C, 55.25; H, 4.44; N,
10.35. Calc. for C43H41BN7O3PW: C, 55.57; H, 4.45; N,
10.55%.
2.5. Tp%(CO)(p-OC6H4Cl)W(p2-(C,C)ꢀOCCPPh3) (8b)
IR (THF, cm−1): wCO 1977, 1877. H NMR (CD2Cl2,
1
A dry, N2 purged, flask was charged with 0.30 g of 5b
and 0.080 g of K[p-OC6H4Cl] before 20 ml of THF was
added. The solution soon turned from purple to green
and another 20 ml of THF was added. The solution
was allowed to stir overnight. Solvent was then re-
moved by rotatory evaporation, and the remaining
green solid was chromatographed on silica. A solution
of 1:4 hexanes:THF was the initial eluent, and then the
proportion of THF was increased gradually until neat
THF was used. The last band was eluted with 4:1
THF:acetonitrile. Five discrete bands came off the
column: an uncolored substance (p-chlorophenol), a
yellow band (identified as pure 9c, vide infra), a brown
band (unidentifiable mixture), a dark green band (also
an unidentifiable mixture), and finally a light green
band. Proton NMR showed that the light green band
was impure, so a second column was performed as
before (silica, 1:3 hexanes:THF ramping to neat aceto-
l): 7.89 (AA%BB%, 4H, C6H4NO2), 5.91, 5.87 (s, 2:1H,
Tp%ꢀCH), 2.48, 2.39, 2.38, 2.36 (s, 3:6:6:3H, Tp% CCH3).
1
13C{1H} NMR (CD2Cl2, l): 222.5 (s, JW–C=161 Hz,
WCO), 214.5 (s, 1JW–C=247 Hz, WꢂCOAr), 159.0,
145.0, 126.4, 117.4 (s, p-C6H4NO2), 152.7, 152.0, 145.9,
145.3 (s, 1:2:1:2C, Tp% CCH3), 107.0, 106.7 (s, 1:2C, Tp%
CH), 16.6, 15.5, 12.8 (s, 2:1:3H, Tp% CCH3). Anal.
Found: C, 41.64; H, 3.87; N, 13.89. Calc. for
C24H26BN7O5W: C, 41.95; H, 3.81; N, 14.27%.
2.7. Tp%(CO)2WꢂCO(p-C6H4Cl) (9c) (continued from
the synthesis of 8b)
The yellow aryloxy carbyne product (0.039 g, 18%
yield) slowly turned black upon exposure to light. IR
1
(KBr, cm−1): wCO 1969, 1864. H NMR (CD2Cl2, l):
7.34 (AA%BB%, 4H, p-C6H4Cl), 5.89, 5.85 (s, 2:1H,
Tp%CH), 2.47, 2.37, 2.36, 2.35 (s, 3:6:6:3H, Tp%CH3).

K.C. Stone et al. / Inorganica Chimica Acta 330 (2002) 161–172
165
13C{1H} NMR (CD2Cl2, l): 222.7 (s, WCO), 218.0 (s,
WꢂCOAr), 153.1, 130.6, 130.2, 118.7 (s, 1:1:2:2C, p-
C6H4Cl), 152.7, 152.1, 145.7, 145.1 (s, 1:2:1:2C,
Tp%CCH3), 106.9, 106.6 (s, 2:1C, Tp%CH) 16.6, 15.5,
12.7 (s, 2:1:3C, Tp%CH3). Anal. Found: C, 43.22; H,
3.95; N, 12.96. Calc. for C24H26BClN6O3W: C, 42.60;
H, 3.87; N, 12.42%.
(s, 1:1:1:1:1:1C, Tp%CCH3), 135.2, 133.2, 130.5, 120.6
1
(d, 3:6:6:3C W(h2-MeOCꢂCPPh3)), 121.4 (d, JP–C
=
321 Hz, W(h2-MeOCꢂCPPh3)), 109.5, 109.0, 108.2 (s,
Tp%CH), 68.5 (s, W(h2-MeOCꢂCPPh3)), 16.0, 15.6,
14.8, 13.2, 12.9, 12.7 (s, Tp%CH3). Anal. Found: C,
47.62; H, 4.13; N, 8.77. Calc. for C44H44BF3N7O8PSW:
C, 47.46; H, 3.98; N, 8.80%.
2.8. Synthesis of [Tp%(CO)(p-OC6H4NO2)-
W(p2-MeOCꢂCPMe2Ph)][OTf ] (10a)
2.10. Tp%(CO)2WꢂCPh (11)
IR (KBr, cm−1): wCO 1969, 1876. H NMR (CD2Cl2,
1
An oven-dried Schlenk flask was charged with 0.62 g
(0.75 mmol) 6a and 50 ml dry CH2Cl2, and cooled to
−78 °C with stirring. Methyl triflate (0.25 ml, 2.20
mmol) was added drop-wise to the cold solution, and
the resulting mixture was slowly warmed to 25 °C.
Upon warming, the solution changed from dark green
to bright green, and a shift in the terminal carbonyl
stretching frequency from 1869 to 1942 cm−1 accompa-
nied the color change. Solvent removal followed by
washing with 2×20 ml Et2O and recrystallization
(CH2Cl2/Et2O, 25 °C) resulted in isolation of 0.53 g
(71% yield) of green crystals of 10a. IR (CH2Cl2,
l): 7.47, 7.33 (m, 2:3H, WCPh), 5.97, 5.87 (s, 2:1H,
Tp%CH), 2.53, 2.48, 2.42, 2.39 (s, 6:3:6:3H, Tp%CH3).
1
13C{1H} NMR (CD2Cl2, l): 277.9 (s, JW–C=187 Hz,
WꢂCPh), 224.2 (s, 1JW–C=166 Hz WCO), 152.8,
152.4, 146.1, 145.4 (s, 1:2:1:2C, Tp%CCH3), 150.5 (d,
2
1C, JW–C=43 Hz, WꢂCꢀCipso), 129.5, 128.4, 127.9 (s,
2:2:1C, WꢂCPh), 107.0, 106.7 (s, 1:2C, Tp%CH), 16.6,
15.3, 12.8, 12.7 (s, 2:1:2:1C, Tp%CH3). Anal. Found: C,
45.57; H, 4.48; N, 12.64. Calc. for C24H27BN6O2W: C,
46.04; H, 4.35; N, 13.42%.
2.11. Collection of diffraction data for
cm−1): wCO 1942. H NMR (CD2Cl2, l): 7.57 (m, 5H,
Tp%(CO)(p-OC6H4NO2)W(p2-C(PMe2Ph)CO) (6a) and
Tp%(CO)(p-OC6H4NO2)W(p2-C(PPh3)CO) (7b) and
[Tp%(CO)(p-OC6H4NO2)W(p2-(C,C)ꢀMeOCꢂ
CPMe2Ph)][OTf ] (10a)
1
W(h2-MeOCꢂCPMe2Ph)), 7.36 (AA%BB%, 4H, W(p-
OC6H4NO2)), 6.06, 6.04, 5.81 (s, Tp%CH), 4.40 (s, 3H,
W(h2-MeOCꢂCPMe2Ph)), 2.56, 2.54, 2.32, 2.08, 1.96,
2
1.83 (s, Tp%CH3), 1.81, 1.64 (d, JP–H=14 Hz, 3:3 H,
W(h2-MeOCꢂCPMe2Ph)). 13C{1H} NMR (CD2Cl2, l):
A dark green crystal of 6a of dimensions 0.40×
0.25×0.15 mm, a dark green crystal of 7b of dimen-
sions 0.40×0.20×0.20, and a green crystal of 10a of
dimensions 0.35×0.30×0.18 mm were selected,
mounted on a glass fiber and coated with epoxy. Dif-
fraction data were collected on a Rigaku automated
diffractometer for 6a and 10a, and a Bruker SMART
diffractometer for 7b. Cell parameters, listed in Table 1,
were refined by least-squares from the positions of 74
well-centered reflections found in the region 30.0B
2qB33.0° and indicated a monoclinic cell for 6a, from
6610 reflections found in the region 5.00B2qB60.00°
and indicated a triclinic cell for 7b, and from 50 well-
centered reflections found in the region 40.0B2qB
45.0° and indicated a triclinic cell for 10a.
3
1
228.7 (d, JP–C=3 Hz, JW–C=150 Hz, W(CO)), 226.2
(d, 2JP–C=16 Hz, W(h2-MeOCꢂCPMe2Ph)), 153.7,
153.6, 153.5, 148.6, 146.7, 146.4 (s, Tp%CCH3), 175.2,
141.2, 125.9, 119.4 (s, W(p-OC6H4NO2)), 135.0, 131.0,
130.6, 123.8 (d, W(h2-MeOCꢂCPMe2Ph)), 116.6 (d,
1JP–C=112 Hz, W(h2-MeOCꢂCPMe2Ph)), 109.2,
109.1, 108.0 (s, Tp%CH), 69.9 (s, W(h2-MeOCꢂ
CPMe2Ph)), 16.0, 15.4, 15.0, 13.0, 12.9, 12.7 (s,
1
Tp%CH3), 12.8, 11.3 (d, JP–C=61 Hz, W(h2-MeOCꢂ
CPMe2Ph)).
2.9. Synthesis of [Tp%(CO)(p-OC6H4NO2)-
W(p2-MeOCꢂCPPh3)][OTf ] (10b)
Complex 10b was prepared in the same manner as
10a, except that chromatography (alumina; eluted with
methylene chloride, then changed to acetonitrile) was
employed before recrystallization. Yield: 48%. IR
Intensity data were collected in the quadrant 9h, k,
l for 6a, the hemisphere 9h, k, 9l for 7b, and
hemisphere 9h, k, 9l for 10a under the conditions
specified in Table 1. Only data with I\2.5|(I) were
used in the structure solution and refinement [13].
1
(CH2Cl2, cm−1): wCO 1945. H NMR (CD2Cl2, l): 8.22,
6.68 (AA%BB%, 2:2H, W(p-OC6H4NO2)), 7.45 (m, 15H,
W(h2-MeOCꢂCPPh3)), 6.17, 5.81, 5.16 (s, 1:1:1H,
Tp%CH), 4.17 (s, 3H, W(h2-MeOCꢂCPPh3)), 2.70, 2.37,
2.32, 2.06, 1.88, 1.55 (s, 3:3:3:3:3:3H, Tp%CH3). 13C{1H}
NMR (CD2Cl2, l): 231.1 (d, 2JP–C=17 Hz, W(h2-
MeOCꢂCPPh3)), 229.3 (d, 3JP–C=3 Hz, W(CO)),
175.0, 141.6, 126.3, 119.0 (s, 1:1:2:2C, W(p-
OC6H4NO2)), 153.84, 153.76, 152.9, 149.1, 146.4, 145.6
2.12. Solution and refinement of structures 6a, 7b and
10a
The space group P21/n was confirmed for 6a by the
(
successful structure solution as was P1 for 7b and 10a.
The asymmetric unit for 7b contains two non-equiva-
lent conformations of 7b. The bond angles and dis-

166
K.C. Stone et al. / Inorganica Chimica Acta 330 (2002) 161–172
Table 1
Crystallographic data collection and refinement parameters for 6a, 7b, and 10a
6a
7b
10a
Empirical formula
Formula weight
Crystal size (mm)
Space group
C32H37BN7O5PW·(22/25)CH2Cl2
900.1
0.40×0.25×0.15
P21/n
C43H41BN7O3PW·(3/4)CH2Cl2
993.17
0.40×0.20×0.20
C
989.41
0.35×0.30×0.18
P1
34H40BF3N7O8PSW
(
(
P1
Unit cell dimensions
,
a (A)
11.405(2)
23.85(1)
13.948(2)
10.9514(4)
21.0989(8)
22.0823(8)
115.416(1)
100.906(1)
95.896(1)
4426.9(3)
4
10.574(1)
12.711(2)
15.394(2)
82.36(1)
80.70(1)
81.718(9)
2007.8(4)
2
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
90.73
3
,
3793(2)
4
1.576
Z
Dcalc (g cm−3
)
1.490
1.637
,
Radiation (u, A)
Monochromator
Mo Ka (0.70930)
graphite
3.19
Mo Ka (0.70930)
graphite
2.79
Mo Ka (0.70930)
graphite
3.09
Linear absorption coefficient
(mm−1
)
Scan mode
Background
q/2q
ꢀ
q/2q
25% of full scan width on both
SMART CCD
25% of full scan with on both sides
sides
2q limits (°)
Quadrant collected
2B2qB45
9h, k, l
4939
5B2qB60
9h, k, 9l
46099
2B2qB45
9h, k, 9l
5236
Total number of reflections
Data with I]2.5|(I)
R (including unobserveds)
RW (including unobserveds)
Goodness-of-fit
3655
20 561
4756
0.047 (0.069)
0.061 (0.063)
1.91
0.065 (0.085)
0.066 (0.071)
2.1287
0.041 (0.045)
0.059 (0.060)
2.17
Number of parameters
Largest parameter shift
451
0.002
1059
0.045
500
0.160
tances for each molecule are close in value, therefore
only one was selected for discussion (see supporting
information). The position of the tungsten atom was
deduced from the three-dimensional Patterson function
for each structure. In each case, the positions of the
remaining non-hydrogen atoms were determined
through subsequent Fourier and difference Fourier
calculations.
3. Results and discussion
3.1. Synthesis of
Tp%(CO)(p-OC6H4R)W(p2-(C,C)ꢀOꢁCCꢀPR%Ph)
2
(R=NO2, R%=Me (6a), R%=Ph (6b); R=CN,
R%=Me (7a); R%=Ph(7b); R=Cl, R%=Ph (8b))
After a THF solution of [Tp%(CO)2WꢂCPMe2Ph]-
[PF6] (5a) and potassium para-nitrophenoxide was
stirred overnight a monocarbonyl product with wCO at
1875 cm−1 was observed by IR. Chromatography on
alumina afforded the h2-ketenyl product Tp%(CO)(p-
OC6H4NO2)W(h2-(C,C)ꢀOꢁCCꢀPMe2Ph) (6a) in 68%
yield. Similar reactions of phosphonium carbyne
complexes 5a and 5b with K[p-OC6H4NO2], K[p-OC6-
H4CN], and K[p-OC6H4Cl] formed the p-nitro adduct
6b, para-cyano complexes 7a and 7b, and the
para-chloro complex 8b, although in poorer yields.
Concomitant formation of the aryloxycarbyne complex
product resulting from phosphine substitution was also
observed in the reaction mixtures (vide infra).
The non-hydrogen atoms were refined using an-
isotropic thermal parameters.1 Hydrogen atom posi-
tions were calculated with use of a CꢀH distance of 0.96
,
A and an isotropic thermal parameter calculated from
the anisotropic values for the atoms to which they were
connected. Final least-squares refinement resulted in
residuals of R=4.7% and RW=6.1% for 6a, R=6.5%
and RW=6.6% for 7b, and R=4.1% and RW=5.9%
for 10a.2 The final difference Fourier map had no peak
greater than 2.00 e A for 6a, 3.680 e A−3 for 7b, and
−3
,
,
−3
,
1.35 e A
for 10a [14].
The dimethylphenylphosphine (6a, 7a, 8a) and
triphenylphosphine (6b, 7b, 8b) h2-ketenyl products
have similar spectroscopic characteristics. Both groups
of complexes contain a stereogenic center at tungsten
1 The function minimized was Sꢀ(ꢀFCꢀ)2, where ꢀ is based on
counter statistics.
2 Runweighted=S(ꢀFOꢀ−ꢀFCꢀ)/SꢀFOꢀ
and
R
weighted=[Sꢀ(ꢀFOꢀ−
2 1/2
ꢀFCꢀ)2/SꢀFO
] .

K.C. Stone et al. / Inorganica Chimica Acta 330 (2002) 161–172
167
and display 1:1:1 patterns for the Tp% methine signals in
the H spectrum. Neglecting coincidental overlap there
[Tp%(CO)2WꢂCPPh3]+ and K[p-OC6H4NO2] by IR
spectroscopy, an absorption consistent with the pres-
ence of Tp%(CO)2WꢂCO(p-C6H4NO2) (9a) was observed
at 1972 cm−1. (The companion dicarbonyl asymmetric
stretch from the aryloxycarbyne complex at 1880 cm−1
is obscured by the 1872 cm−1 absorption of the ketenyl
product.) Observation of the 1972 cm−1 IR signal of
the carbyne complex prompted a control experiment
where phosphonium carbyne complex 5b and p-nitro-
1
are six resonances of equal intensity for the six methyl
groups of the Tp% ligand located between 2.5 and 1.5
ppm in the 1H spectra with the associated carbons
somewhere between 16.0 and 12.0 ppm in the 13C
spectra. The range of carbon chemical shifts for the
ketenyl carbon attached to oxygen is narrow (201–204
ppm), and lies close to reported chemical shift values
for other h2-ketenyl complexes [15].
1
phenoxide were stirred for 20 h in THF, and then a H
Closer inspection of the spectroscopic data reveals
some differences between the dimethylphenylphospho-
nium and triphenylphosphonium derivatives. The 1:1:1
patterns in the 1H NMR spectra of the methine protons
on the Tp% ligand are significantly more dispersed in
spectra of the triphenylphosphonium derivatives (6b,
7b, 8b). One of the Tp% methine protons resonates
unusually far upfield, near 5.0 ppm, probably due to
shielding by the phenyl rings of the triphenylphosphine
substituent (c.f. crystal structures, vide infra). The two
signals from the diastereotopic phosphine methyl
groups of PMe2Ph complex 6a are differentiated from
Tp% methyl signals by phosphorus coupling. Ketenyl
products generated from dimethylphenylphosphonium
carbyne complex 5a resonate near 15 ppm in 31P NMR
spectra, while those generated from triphenylphospho-
nium complex 5b resonate near 20 ppm. Crystal struc-
tures of h2-ketenyl p-nitrophenoxide/dimethylphenyl-
phosphine adduct 6a and h2-ketenyl p-cyanophenoxide/
triphenylphosphine adduct 7b reveal that the ketenyl
orientation positions the phosphine substituents proxi-
mal to the Tp% ligand. A single rotomer of the phospho-
ranylideneketene is observed in solution for all ketenyl
products.
NMR spectrum was obtained of the residue remaining
after solvent removal. The spectrum revealed a product
ratio of approximately 60:1 h2-ketenyl com-
plex:aryloxycarbyne product (6b to 9a), based on inte-
gration of the methine and methyl proton signals. The
syntheses of the h2-ketenyl complexes 6a, 7a, 7b, and 8b
were reproduced under the same standardized condi-
tions. The ratio of the starting materials (1.5:1 arylox-
ide nucleophile:cationic carbyne complex) was held
constant, and all of the reactions were stirred in THF
for 20–24 h before solvent removal. The product ratios
determined by NMR are listed in Table 2.
In contrast to the results with electron poor aryloxide
reagents, the reaction of p-methoxyphenoxide with
phosphonium carbyne complex 5a produced only para-
methoxyphenoxycarbyne complex 9f. The p-nitro sub-
stituent on an aryloxide reduces the nucleophilicity of
the oxide oxygen while the p-methoxy substituent in-
creases the nucleophilicity of the oxide oxygen. Like-
wise, only aryloxycarbyne product was observed from
the reactions of 5a with phenoxide and p-chlorophe-
noxide. No h2-ketenyl coupled complexes were detected
in reactions of 5b with phenoxide or p-chlorophenoxide
or p-methoxyphenoxide.
Formation of h2-ketenyl coupled products (P1) and
aryloxycarbyne products (P2) was not reversible, so the
product distribution reflects the ratio of the rates of
formation of the two products. This linear free energy
relationship can be probed by plotting log([P1]/[P2])
versus |para for the three aryloxide reagents where both
products (P1 and P2) could be detected from the reac-
tion with Tp%(CO)2WꢂCPPh3][PF6] (5b). The plot re-
veals a general trend toward less ketenyl product as the
electron donating power of the para-substituent in-
creases (Fig. 2). Even from a qualitative perspective it is
predictable that no ketenyl product was detected for the
reaction of 5b with potassium phenoxide, and indeed
the plot extrapolates to roughly 100:1 favoring the
aryloxycarbyne at |para=0. The points representing the
reactions of 5a with p-cyanophenoxide and p-nitrophe-
noxide are below the points for the reactions of 5b with
potassium aryloxides. Therefore, it is not surprising
that no ketenyl product was detected from the reaction
of p-chlorophenoxide with 5a. These results are consis-
tent with the mechanism in Scheme 4.
3.2. Product ratios of aryloxy substituted carbyne
complexes and p2-ketenyl coupled products generated
from phosphonium carbyne complexes
While monitoring the formation of ketenyl product
6b (absorptions at 1872 and 1710 cm−1
) from
Table 2
Product ratios from phosphine substitution and carbonyl–carbyne
ligand coupling in phosphonium carbyne complexes
K[p-OC6H4R] [Tp%(CO)2WCPMe2Ph]- [Tp%(CO)2WCPPh3]-
[PF6]
[PF6]
R=
(carbyne:h2-ketenyl)
(carbyne:h2-ketenyl)
OCH3
CH3
H
Cl
CN
NO2
carbyne only
carbyne only
carbyne only
carbyne only
1:2
carbyne only
carbyne only
carbyne only
6:1
1:5
1:60
1:3

168
K.C. Stone et al. / Inorganica Chimica Acta 330 (2002) 161–172
phosphine to act as a leaving group, seem incompatible
with the observed product ratios. Greater electron den-
sity at the carbyne carbon of 5a ([W]ꢂCPMe2Ph+)
would reduce the electrophilicity of that site and more
h2-ketenyl coupled product would be expected. This is
not observed. Dimethylphenylphosphine is expected to
be a poorer leaving group than triphenylphosphine, but
more carbyne product forms in reactions with 5a. Al-
though steric factors are compatible with more substi-
tution at the carbyne carbon with PMe2Ph in the
reagent and more coupling product formation with
PPh3 in the reagent, the determinants of product distri-
bution remain debatable.
Fig. 2. Plot of log([ketene]/[carbyne]) versus |para. Reactions with 5a
are represented by triangles (ꢀ) and reactions of 5b are represented
by squares (ꢁ).
3.4. Attempts to detect p2-ketenyl coupled product in
reactions of phosphonium carbyne complex 5 with
phenoxide, p-methylphenoxide, and
p-methoxyphenoxide
The h2-ketenyl coupled products (6–8) each have one
strong IR carbonyl stretching absorption for the WꢀCO
unit located somewhere between 1861 and 1875 cm−1
.
The less intense ketenyl CO absorption occurs at lower
energy, between 1706 and 1722 cm−1. The aryloxy
carbyne products (9) have symmetric and antisymmet-
ric CO vibrations near 1970 and 1870 cm−1. Because
the antisymmetric carbonyl stretch is strongly ab-
sorbing in the IR region, attempting to determine the
presence of h2-ketenyl product by IR spectroscopy is
difficult due to overlap in the 1870 cm−1 region. The
IR spectrum of the reaction products is further compli-
cated by aryl CꢀH stretching overtones [16] that absorb
in the same region as the ketenyl carbonyl (e.g. an
absorption is observed at 1714 cm−1 for free PPh3).
When complex 5 was reacted with the phenoxides with
hydrogen, methyl, and methoxy in the para-position,
the major products were 9d, 9e, and 9f, respectively,
and no h2-ketenyl coupled product was observed. The
aryloxy carbyne products were isolated in low yields
and identified by NMR based on literature values [9].
3.5. Molecular structures of Tp%(CO)(p-OC6H4NO2)-
W(p2-(C,C)ꢀOꢁCCꢀPMe2Ph) (6a) and
Scheme 4.
Tp%(CO)(p-OC6H4CN)W(p2-(C,C)ꢀOꢁCCꢀPPh3) (7b)
3.3. Reacti6ity trends between the
dimethylphenylphosphonium carbyne (5a) and
triphenylphosphonium carbyne (5b) complexes
ORTEP drawings of the solid-state molecular struc-
tures of 6a and 7b are shown in Figs. 3 and 4, respec-
tively; selected bond distances and angles are shown in
Tables 3 and 4. Each complex can be described as a
distorted octahedron if the h2-ketenyl ligand is consid-
ered to occupy a single coordination site.
The bonding parameters of the phosphoranyli-
deneketene ligands in 6a and 7b are congruent with
the ligand geometry in Cl2(PMePh2)2(CO)W(h2-
C(PMePh2)CO) reported by Hillhouse [17,18]. Short
A larger proportion of substituted carbyne product is
formed in reactions with 5a ([W]ꢂCPMe2Ph+)
([W]ꢁTp%(CO)2W) than with 5b ([W]ꢂCPPh3+). The
difference in product ratios may be due to the greater
+
steric bulk of the [W]ꢂCPPh3 reagent, with the bulky
PPh3 substituent inhibiting nucleophilic attack at the
carbyne carbon. Electronic factors, such as electron
density at the carbyne carbon or the ability of the
,
,
W(1)ꢀC(3) bond lengths (1.998(11) A (6a), 2.031(6) A

K.C. Stone et al. / Inorganica Chimica Acta 330 (2002) 161–172
169
(7b)) suggest a multiple bond. Typical h2-ketenyl WꢁC
bond distances (where C is the carbon adjacent to the
Table 3
,
Selected bond distances (A), angles (°), and torsion angles for 6a
,
carbonyl) are on the order of 1.97–2.0 A, whereas
Bond distances
h1-ketenyls have MꢀC bond lengths in the range of
W(1)ꢀC(1)
W(1)ꢀO(3)
W(1)ꢀC(2)
W(1)ꢀC(3)
1.872(13)
2.016(7)
2.212(11)
1.998(11)
C(2)ꢀC(3)
C(2)ꢀO(2)
C(3)ꢀP(1)
O(3)ꢀC(4)
1.285(16)
1.211(15)
1.743(11)
1.317(13)
,
2.2–2.3 A [15,19]. Even the W(1)ꢀC(2) interatomic
distances of 2.212(11) A (6a) and 2.185(6) A (7b) are
,
,
Bond angles
C(1)ꢀW(1)ꢀO(3)
W(1)ꢀO(3)ꢀC(4)
W(1)ꢀC(2)ꢀO(2)
W(1)ꢀC(2)ꢀC(3)
97.0(4)
134.4(7)
144.5(8)
63.3(7)
O(2)ꢀC(2)ꢀC(3)
W(1)ꢀC(3)ꢀC(2)
W(1)ꢀC(3)ꢀP(1)
C(2)ꢀC(3)ꢀP(1)
152.1(11)
81.6(7)
143.5(7)
132.0(9)
Torsion angles
O(2)ꢀC(2)ꢀC(3)ꢀP(1)
C(1)ꢀW(1)ꢀC(2)ꢀC(3)
+13.5(5)
+12.7(11)
Table 4
,
Selected bond distances (A), angles (°), and torsion angles for 7b
Bond distances
W(1)ꢀC(1)
W(1)ꢀO(3)
W(1)ꢀC(2)
W(1)ꢀC(3)
1.927(6)
2.021(4)
2.185(6)
2.031(6)
C(2)ꢀC(3)
C(2)ꢀO(2)
C(3)ꢀP(1)
C(4)ꢀO(3)
1.362(9)
1.226(8)
1.721(6)
1.333(7)
Bond angles
C(1)ꢀW(1)ꢀO(3)
W(1)ꢀO(3)ꢀC(4)
W(1)ꢀC(2)ꢀO(2)
W(1)ꢀC(2)ꢀC(3)
94.96(22) O(2)ꢀC(2)ꢀC(3)
147.0(6)
77.4(4)
155.5(4)
126.1(5)
135.1(4)
147.8(5)
65.1(4)
W(1)ꢀC(3)ꢀC(2)
W(1)ꢀC(3)ꢀP(1)
C(2)ꢀC(3)ꢀP(1)
Torsion angles
O(2)ꢀC(2)ꢀC(3)ꢀP(1)
C(1)ꢀW(1)ꢀC(2)ꢀC(3)
−11.5(4)
+6.6(5)
shorter than WꢀCbenzyl single bonds (i.e. rW–C=2.28(7)
Fig. 3. Thermal ellipsoid representation of 6a.
,
A (avg.) in Cp2W(CH2Ph)2 [20]). C(2)ꢀC(3) distances of
,
,
1.285(16) A (6a) and 1.362(9) A (7b) are comparable to
2
,
other h -ketenyl CꢀC bonds (1.323(9) A in (dppe)-
(detc)(CO)W(h2-C(CH2Ph)CO) [21], 1.37(1)
A
in
[15,19],
,
Cl2(PMePh2)2(CO)W(h2-C(PMePh2)CO)
2
,
1.32(4) A in Cp(CO)(PMe3)W(h -C(p-tol)CO) [22]. The
,
,
C(3)ꢀP(1) distances of 1.743(11) A (6a) and 1.721(6) A
(7b) reflect bonding of a formal phosphonium sub-
stituent to a carbon nucleus [9], and the C(2)ꢀO(2)
,
,
bond lengths (1.211(15) A (6a) and 1.226(8) A (7b)) are
typical of h2-ketenyl CꢁO distances [15,19].
A slight twisting of the h2-ketenyl (or metallacyclo-
propanone) moiety from a parallel alignment with the
terminal tungsten–carbonyl axis is seen (C(1)ꢀW(1)ꢀ
C(3)ꢀC(2)=12.7(11)° (6a), 6.6(5)° (7b)). The four-atom
ketenyl OꢀCꢀCꢀP linkage is slightly distorted from
planarity
(O(2)ꢀC(2)ꢀC(3)ꢀP(1)=13.5(5)°
(6a),
−11.5(4)° (7b)). A rationale for the preferential orien-
tation of the ketenyl CO proximal to the terminal
carbonyl ligand in d4 Ln(CO)M complexes has been
published [23], and the donor properties of ketenyl
ligands bound to d4 metal fragments have been de-
scribed [21]. The orientation of the h2-ketenyl ligand in
Fig. 4. Thermal ellipsoid representation of 7b.

170
K.C. Stone et al. / Inorganica Chimica Acta 330 (2002) 161–172
both 6a and 7b reflects the ability of this unsaturated
ligand to interact constructively with the d orbitals of
the d4 W(II) center [24].
lization from CH2Cl2/Et2O, which provided light green
crystals of 10b in 48% yield.
1H NMR analysis of the crude reaction residue of
10a indicated the presence of two isomers of the
cationic alkyne product in a 5:2 ratio. Following recrys-
tallization, however, only those signals corresponding
to the major isomer were observed. We believe the two
isomers reflect two possible orientations of the alkyne
ligand, one in which the phosphonium substituent
resides close to the Tp% pyrazole rings, and the other in
which the methoxy group is proximal to the Tp% ligand.
The triphenylphosphine substituent in 10b is larger than
the PMe2Ph moiety of 10a and only one isomer of 10b
is observed. In addition to aromatic signals due to the
phosphorus-bound phenyl group and aryloxide ligands,
distinct signals for each Tp% pyrazole indicate C1 sym-
metry for 10a and 10b. Diastereotopic phosphine
The four metal based electrons reside in two dp
orbitals directed toward the p-acid CO ligand. One
aryloxide lone pair residing in an orbital of largely
oxygen p character is aligned to interact with the lone
empty dp orbital of tungsten. The WꢀOꢀC bond angle
at O(3) is 134.4(7)° for 6a and 135.1(4)° for 7b; hy-
bridization at O(3) is between sp2 and sp. The torsion
angles (absolute values) defined by C(1)ꢀW(1)ꢀO(3)ꢀ
C(4) (18.3(6)° (6a) and 34.5(5)° (7b)) position the oxy-
gen lone pair with more p character so that donation to
the vacant dp orbital is possible. Bond lengths of
,
,
2.016(7) A (6a) and 2.021(4) A (7b) for the tungsten–
alkoxide bonds are in the typical range for W(VI) d0
complexes, suggesting that some p-donation from the
aryloxide ligand to tungsten is present [25,26].
2
methyl doublets (l 1.81 ppm, JP–H=15 Hz; 1.64 ppm,
2JP–H=14 Hz) are observed for 10a. The methoxy
group on the alkyne ligand appears as a singlet at 4.40
ppm for 10a and as a singlet at 4.17 ppm for 10b.
Phosphorus coupled doublets at 226 ppm (2JP–C=16
Hz) and 117 ppm (1JP–C=112 Hz) in the 13C NMR
spectrum are assigned to the methoxy-bearing and
phosphonium-bearing alkyne carbons of 10a, respec-
3.6. Nucleophilicity of the neutral p2-ketenyl
complexes: formation of [Tp%(CO)(p-OC6H4NO2)-
W(p2-MeOCCPMe2Ph)][OTf ] (10a) and
[Tp%(CO)(p-OC6H4NO2)W(p2-MeOCCPPh3)][OTf ]
(10b)
Electrophilic addition to the oxygen of h2-ketenyl
ligands is a well-established route to alkoxyalkyne com-
plexes [15,19,24]. Addition of methyl triflate to an
olive-green CH2Cl2 solution of either neutral h2-ketenyl
complex 6a or 6b at −78 °C followed by warming to
25 °C generated bright green cationic methoxyalkyne
complexes 10a and 10b, respectively, affirming the nu-
cleophilic character of the ketenyl oxygen (Scheme 5).
A shift in the frequency of the lone terminal metal
carbonyl stretch of the h2-ketenyl complexes (wCO 6a,
1869 cm−1; 6b, 1872 cm−1) to a higher frequency in
the monocarbonyl alkyne complex (wCO 10a, 1942
cm−1; 10b, 1945 cm−1) accompanies the transforma-
tion, and the h2-ketenyl CO stretch of the reagents (6a,
1718 cm−1; 6b, 1710 cm−1) disappears. Recrystalliza-
tion of the reaction mixture from CH2Cl2/Et2O pro-
vided a 71% isolated yield of the cationic alkyne
complex 10a. The reaction product containing 10b re-
quired chromatography on alumina prior to recrystal-
tively (231 ppm (2JP–C=17 Hz) and 121 ppm (1JP–C
=
321 Hz) for 10b). The coupling between the phosphorus
and the directly connected alkyne carbon in 10b is
unusually large, however phosphorus–carbon single-
bond coupling is known to approach 450 Hz [27]. Two
compounds that are similar in PꢀC linkage structure to
the alkyne ligand are ketenylidenetriphenylphosphorane
1
(Ph3PꢁCꢁCꢁO), which has a JP–C=190 Hz [28] and
the carbodiphosphorane (Me2N)3PꢁCꢁP(NMe2)3, which
1
has a JP–C=304.7 Hz [29]. As in the case of ketenyl
complexes 6a and 6b, the phosphonium-bearing alkyne
carbon resonance occurs at unusually high field for a
coordinated four-electron donor alkyne complex [24].
The terminal carbonyl resonates at 229 ppm (1JW–C
150 Hz, 3JP–C=3 Hz) for 10a and at 229 ppm (3JP–C
=
=
3 Hz) for 10b. The methoxide substituent on the alkyne
gives rise to a 13C NMR singlet at 70 ppm for 10a and
at 68.5 ppm for 10b, and diastereotopic methyl doublets
from the phosphonium group of 10a appear at 12.8 and
11.3 ppm (1JP–C=61 Hz).
3.7. Molecular structure of [Tp%(CO)(p-OC6H4NO2)-
W(p2-MeOCꢂCPMe2Ph)][OTf ] (10a)
An ORTEP drawing of the solid-state molecular struc-
ture of 10a is shown in Fig. 5; selected bond distances
and angles are shown in Table 5. The complex is
pseudo-octahedral if the alkyne ligand is considered to
occupy only a single coordination site.
The orientation and geometry of the alkyne ligand
Scheme 5.
are consistent with expectations for h2-alkyne coordina-

K.C. Stone et al. / Inorganica Chimica Acta 330 (2002) 161–172
171
Bond angle summations of 360° about C(2) and 357°
about C(3) indicate essentially planar geometries at the
alkyne carbons, consistent with the bonding scenario
for d4 L(CO)M(h2-RCꢂCR%)X complexes [24]. The two
most significant resonance contributors are shown Fig.
6.
3.8. Related reactions: formation of Tp%(CO)2WꢂCPh
(11), and Tp%(CO)2WꢂCH (12)
Two additional tungsten carbyne byproducts deserve
mention. An orange side product, Tp%(CO)2WꢂCPh
(11), is commonly observed during reactions of phos-
phonium carbyne complex 5 with nucleophiles [32,33].3
A methylidyne complex, Tp%(CO)2WꢂCH (12), defini-
tively identified based on comparison with literature
data, was also isolated from some aryloxide addition
reactions [11]. Both side products probably result from
similar intermediates. Quaternary phosphonium salts
are known to react with hydroxide in organic solvents
to give a dissociated alkyl anion or a product resulting
from a 1,2-phenyl migration (Scheme 6) [34]. The most
stable carbanion typically dissociates [35], and for
triphenyl phosphonium carbyne complex 5b one possi-
ble dissociating carbanion could be the anionic carbide
complex. At low temperature (−78 °C), phenyl migra-
tion seems to be inhibited and only the protonated
carbide dissociation product, 12, was observed for the
reaction with p-cresolate (K[p-OC6H4CH3]). Solid
potassium hydroxide was combined with a solution of
[Tp%(CO)2WꢂCPPh3][PF6] in THF at −78 °C and no
reaction occurred until the solution was warmed
(sodium hydroxide is virtually insoluble in THF) and
Fig. 5. Thermal ellipsoid representation of 10a.
Table 5
,
Selected bond distances (A) and angles (°) for 10a
Bond distances
W(1)ꢀC(1)
W(1)ꢀO(3)
W(1)ꢀC(2)
W(1)ꢀC(3)
C(2)ꢀC(3)
1.960(8)
2.009(5)
2.042(8)
2.077(8)
1.320(11)
C(2)ꢀO(2)
C(3)ꢀP(1)
P(1)ꢀC(10)
P(1)ꢀC(11)
P(1)ꢀC(12)
1.335(9)
1.748(8)
1.774(10)
1.777(10)
1.799(8)
Bond angles
C(1)ꢀW(1)ꢀO(3)
W(1)ꢀO(3)ꢀC(4)
W(1)ꢀC(2)ꢀO(2)
W(1)ꢀC(2)ꢀC(3)
92.7(3)
133.7(4)
142.7(6)
72.8(5)
C(3)ꢀC(2)ꢀO(2)
W(1)ꢀC(3)ꢀC(2)
W(1)ꢀC(3)ꢀP(1)
C(2)ꢀC(3)ꢀP(1)
144.3(8)
69.8(5)
145.2(4)
141.5(7)
Fig. 6.
tion in d4 L(CO)M(h2-alkyne)X complexes [22–24].
The unusual alkyne ligand is bound to the tungsten
nucleus with tungsten–carbon distances typical of h2-
Scheme 6.
,
A;
alkyne
coordination
(W(1)ꢀC(2)=2.042(8)
,
W(1)ꢀC(3)=2.077(8) A) [30]. The four electron-donor
alkyne ligand displays an elongated C(2)ꢀC(3) bond
3 Tp%(CO)2WCPh is the tungsten analog of the molybdenum com-
plex Tp%(CO)2MoCPh which has been reported in Refs. [32,33].
,
distance (1.320(11) A) relative to free alkynes [31].

172
K.C. Stone et al. / Inorganica Chimica Acta 330 (2002) 161–172
[4] N.M. Kostic’, R.F. Fenske, Organometallics 1 (1982) 489.
[5] J. Ushio, H. Nakatsuji, T. Yonezawa, J. Am. Chem. Soc. 106
(1984) 5892.
[6] R.A. Doyle, R.J. Angelici, Organometallics 8 (1989) 2207.
[7] H.P. Kim, S. Kim, R.A. Jacobson, R.J. Angelici, Organometal-
lics 5 (1986) 2481.
[8] T. Desmond, F.J. Lalor, G. Ferguson, M. Parvez, J. Chem. Soc.,
Chem. Commun. (1983) 457.
[9] G.M. Jamison, P.S. White, J.L. Templeton, Organometallics 10
(1991) 1954.
then the reaction proceeded slowly. At room tempera-
ture, Tp%(CO)2WꢂCPh and Tp%(CO)2WꢂCH carbyne
complexes were formed in approximately equal
amounts. Rigorous exclusion of water during the
preparation of potassium aryloxide and drying the
phosphonium carbyne complex in vacuo reduced the
amount of phenyl and CꢀH carbyne products to unde-
tectable levels.
[10] A.E. Bruce, A.S. Gamble, T.L. Tonker, J.L. Templeton,
Organometallics 6 (1987) 1350.
[11] A.E. Enriquez, P.S. White, J.L. Templeton, J. Am. Chem. Soc.
123 (2001) 4992.
4. Summary
[12] A.B. Pangborn, M.A. Giardello, R.H. Grubbs, R.K. Rosen, F.J.
Timmers, Organometallics 15 (1996) 1518.
[13] E.J. Gabe, Y. Le Page, J.P. Charland, F.L. Lee, P.S. White, J.
Appl. Crystallogr. 22 (1989) 384.
[14] Scattering factors were taken from the following: D.T. Cromer,
J.T. Waber, in: J.A. Ibers, J.C. Hamilton, (Ed.), International
Tables for X-Ray Crystallography, Kynoch, Birmingham, Eng-
land, 4 (1974) Table 2.2.
[15] A. Mayr, C.M. Bastos, Prog. Inorg. Chem. 40 (1992) 1.
[16] J.B. Lambert, H.F. Shurvell, D.A. Lightner, R.G. Cooks, Or-
ganic Structural Spectroscopy, Prentice Hall, Upper Saddle
River, 1998.
[17] A.K. List, G.L. Hillhouse, A.L. Rheingold, J. Am. Chem. Soc.
110 (1988) 4855.
[18] A.K. List, G.L. Hillhouse, A.L. Rheingold, Organometallics 8
(1989) 2010.
[19] A. Mayr, C.M. Bastos, R.T. Chang, J.X. Haberman, K.S.
Robinson, D.A. Belle-Oudry, Angew. Chem., Int. Ed. Engl. 31
(1992) 747.
[20] R.A. Forder, I.W. Jefferson, K. Prout, Acta Crystallogr., Sect. B
B31 (1975) 618.
Tungsten h2-phosphoranylideneketene and aryloxy
carbyne complexes have been synthesized from phos-
phonium carbyne precursors. The product ratio of
phosphine replacement by aryloxide at the carbyne
carbon to carbonyl coupling products can be tuned by
variation of the aryloxy para-substituent in order to
tune the aryloxide nucleophilicity. Aryloxy carbyne
complexes are the favored products with stronger nu-
cleophiles. Weaker nucleophiles result in a mixture of
aryloxy carbyne complexes and h2-ketenyl coupled
complexes. Formation of h2-ketenyl complexes is fa-
vored for the least nucleophilic aryloxides. Methylation
of two neutral h2-ketenyl complexes to form cationic
methoxy alkyne complexes was accomplished, in accord
with the anticipated nucleophilicity of the ketenyl
oxygen.
[21] K.R. Birdwhistell, T.L. Tonker, J.L. Templeton, J. Am. Chem.
Soc. 107 (1985) 4474.
[22] F.R. Kreissl, P. Friedrich, G. Huttner, Angew. Chem., Int. Ed.
Engl. 16 (1977) 102.
5. Supplementary material
Complete tables of atomic parameters, anisotropic
temperature factors, bond distances, and bond angles
for 6a, 7b, and 10a as well as drawings with numbering
schemes are available (37 pages). Torsion angles are
also provided for 6a and 7b. Ordering information is
available on any current masthead page.
[23] D.C. Brower, K.R. Birdwhistell, J.L. Templeton, Organometal-
lics 5 (1986) 94.
[24] J.L. Templeton, Adv. Organomet. Chem. 29 (1989) 1.
[25] A.J. Nielson, J.M. Waters, Polyhedron 1 (1982) 561.
[26] M.H. Chisholm, Polyhedron 2 (1983) 681.
[27] R.G. Cavell, J.A. Gibson, K.I. The, J. Am. Chem. Soc. 99 (1977)
7841.
[28] L. Pandolfo, G. Paiaro, L.K. Dragani, C. Maccato, R. Bertani,
G. Facchin, L. Zanotto, P. Ganis, G. Valle, Organometallics 15
(1996) 3250.
[29] R. Appel, U. Baumeister, F. Knoch, Chem. Ber. 116 (1983)
2275.
[30] C.P. Casey, T.J. Burkhardt, C.A. Bunnell, J.C. Calabrese, J. Am.
Chem. Soc. 99 (1977) 2127.
[31] D.R. Lide (Ed.), CRC Handbook of Chemistry and Physics,
75th ed., CRC, Boca Raton, FL, 1995.
Acknowledgements
We thank the National Science Foundation and the
US Department of Energy, Division of Chemical Sci-
ences (Grant 85ER13430), for financial support.
[32] D.C. Brower, M. Stoll, J.L. Templeton, Organometallics
(1989) 2786.
[33] T. Desmond, F.J. Lalor, G. Ferguson, M. Parvez, J. Chem. Soc.,
8
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