Facile C-N bond cleavage mediated by electron-rich cyclopentadienyl cobalt(I) complexes

Article abstract of DOI:10.1016/S0022-328X(98)00362-3

The reaction of [C₅H₅Co(PMe₃)₂] (1) with one equiv of CNCH₂Ph leads to the formation of the substitution product [C₅H₅Co(CNCH₂Ph)(PMe₃)] (2) which even at room temperature undergoes an intramolecular oxidative addition to give the isomer [C₅H₅Co(CN)(CH₂Ph)(PMe₃)] (4). The corresponding Cp*Co derivative [C₅Me₅Co(CN)(CH₂Ph)(PMe₃)] (8) is obtained from [C₅Me₅Co(PMe₃)₂] (5) and CNCH₂Ph. In contrast to 2, the analogous compound [C₅H₅Co(CNTol)(PMe₃)] (6) is quite inert and does not react by N-C bond cleavage. The conversion of 2 to 4 in C₆D₆, acteone-d₆ and methanol-d₄ follows first order kinetics with a rate that is almost independent of the concentration of free PMe₃. Both 2 and 6 react with Ph₂CN₂ to give the C,C-bound ketenimine complexes [C₅H₅Co(κ²-C,C-Ph₂C=C=NR)(PMe₃)] (9, 10) of which that with R=Tol rearranges thermally to the more stable N,C-bound isomer 11.

Full text of DOI:10.1016/S0022-328X(98)00362-3

Journal of Organometallic Chemistry 562 (1998) 45–51
Facile C–N bond cleavage mediated by electron-rich cyclopentadienyl
cobalt(I) complexes1
Helmut Werner a,*, Gerhard Ho¨rlin a, William D. Jones b
a Institut fu¨r Anorganische Chemie der Uni6ersita¨t, Am Hubland, D-97074 Wu¨rzburg, Germany
b Department of Chemistry, Uni6ersity of Rochester, Rochester, New York 14627, USA
Received 17 June 1997
Abstract
The reaction of [C5H5Co(PMe3)2] (1) with one equiv of CNCH2Ph leads to the formation of the substitution product
[C5H5Co(CNCH2Ph)(PMe3)] (2) which even at room temperature undergoes an intramolecular oxidative addition to give the
isomer [C5H5Co(CN)(CH2Ph)(PMe3)] (4). The corresponding Cp*Co derivative [C5Me5Co(CN)(CH2Ph)(PMe3)] (8) is obtained
from [C5Me5Co(PMe3)2] (5) and CNCH2Ph. In contrast to 2, the analogous compound [C5H5Co(CNTol)(PMe3)] (6) is quite inert
and does not react by N–C bond cleavage. The conversion of 2 to 4 in C6D6, acteone-d6 and methanol-d4 follows first order
kinetics with a rate that is almost independent of the concentration of free PMe3. Both 2 and 6 react with Ph2CN2 to give the
C,C-bound ketenimine complexes [C5H5Co(s2-C,C-Ph2CꢀCꢀNR)(PMe3)] (9, 10) of which that with R=Tol rearranges thermally
to the more stable N,C-bound isomer 11. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Cobalt; Isocyanide complexes; C–N bond cleavage; Ketenimine complexes
1. Introduction
the starting material 2 as well as the in-situ formed
C5Me5Co analogue is quite labile even in the absence of
Following our work on isocyanide cobalt(I) com-
any reagent and undergoes facile N–CH2Ph bond
plexes of the general composition [C5H5Co(CNR)
cleavage. In this paper we describe the characterization
(PMe3)], which react with 1,2- and 1,3-dipoles to give
of the respective products and discuss the kinetic data
four- and five-membered metallaheterocycles [1,2], we
of the metal-assisted dissociation process.
recently reported also on the reactivity of these half-
sandwich-type compounds towards diazoalkanes [3]
and arylazides [4]. In particular, the possibility to gener-
ate unsymmetrical carbodiimides such as PhCH2
2. Results and discussion
NꢀCꢀNPh from benzylisocyanide PhCH2NC and PhN3
in the coordination sphere of cobalt prompted us to
continue our investigations regarding the behavior of
[C5H5Co(CNCH2Ph)(PMe3)] (2) towards other sub-
strates. In the course of these studies we observed that
2.1. Preparation and rearrangement of isocyanide
cobalt complexes
Using the electron-rich cyclopentadienyl complex 1
as the starting material, the isocyanide derivatives 2 and
3 are prepared by stepwise replacement of the phos-
phine ligands by benzylisocyanide. While 2 has been
identified by analytical and spectroscopic techniques [4],
the characterization of 3 turned out to be more
difficult. The brown solid is extremely air-sensitive and
* Corresponding author. Tel.: +49 931 8815260; fax: +49 931
8884605.
1 Dedicated to Professor R.B. King on the occasion of his 60th
birthday.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00362-3

46
H. Werner et al. / Journal of Organometallic Chemistry 562 (1998) 45–51
Scheme 1.
thus no correct elemental analysis could be obtained.
The IR spectrum of 3 displays CꢁN stretching frequen-
cies at 2093, 1970 and 1935 cm−1, i.e. at similar posi-
tions as found for other [C5H5Co(CNR)2] complexes
[5]. The 1H-NMR data are also consistent with the
structural proposal shown in Scheme 1 and deserve no
further comments.
Compound 2, which has already been used as precur-
sor for the synthesis of ketenimine cobalt derivatives
[4], is thermally rather labile and undergoes an isomer-
ization to the benzyl(cyano)cobalt(III) complex 4 even
at room temperature. After stirring a solution of 2 in
benzene for 12 h, 4 has been isolated as an orange, only
slightly air-sensitive solid in 83% yield. The most typical
spectroscopic features of 4 are the intense w(CꢁN)
stretch at 2082 cm−1 in the IR and the two signals
(corresponding to the AB part of an ABX spin system)
at l 2.67 and 2.53 for the benzylic CH2 protons in the
1H-NMR spectrum.
However, an extremely facile N–C bond cleavage
occurs on treatment of 5 with benzylisocyanide. If a
solution of 5 and CNCH2Ph in benzene/ether is stirred
at 0°C for 2–3 min, the benzyl(cyano)cobalt(III) com-
plex 8 is formed and upon recrystallization from ether
isolated as an orange solid in 74% yield. Apart from the
IR spectrum, in which an intense CꢁN stretching fre-
quency appears at 2091 cm−1, the NMR data of 8 are
also in good agreement with the structural proposal
depicted in Scheme 3. The 13C-NMR spectrum displays
two doublets at l 138.2 and 12.4, which both show a
strong P–C coupling and are assigned to the metal-
bound CN and CH2Ph carbon atoms, respectively. It
should be mentioned that halfsandwich-type benzyl-
cobalt(III) compounds of the general composition
[C5H5Co(CH2Ph)(R)(PPh3)] (R=CH3, CH2Ph) are
known and have been prepared from [C5H5CoI2(PPh3)]
and Grignard reagents [6].
In contrast to 2, the related 4-tolylisocyanide com-
plex 6 (Scheme 2) does not rearrange in solution to the
cobalt(III) isomer [C5H5Co(CN)(4-C6H4Me)(PMe3)].
Compound 6, which has been obtained from equimolar
amounts of 1 and CNTol in benzene/pentane, is an
orange, very air-sensitive solid decomposing already at
2.2. Kinetic studies
In order to find out along which mechanistic route
the benzyl(cyano)cobalt(III) complexes 4 and 8 are
formed, the kinetics of the reaction of 2 to 4 have been
investigated. Since it seemed at least conceivable that
ionic or radical intermediates are involved the rate
measurements were performed in different solvents
(C6D6, acetone-d6 and methanol-d4) and in the presence
of radical scavengers such as cyclohexa-1.3-diene. The
change in concentration of 2 and 4 during the runs was
34°C.
The
corresponding
Cp*Co
derivative
[C5Me5Co(CNTol)(PMe3)] could not be prepared from
[C5Me5Co(PMe3)2] (5) and CNTol since the first step of
this process (replacement of one PMe3 by CNTol) is
quickly followed by the second one and thus the bi-
s(isocyanide) compound 7 is obtained. By using a molar
ratio of 6/CNTol=1/2, the yield of 7 is 83%. The IR
spectrum of 7 displays three w(CꢁN) bands at 2063,
2032 and 1920 cm−1 which are shifted to somewhat
lower frequencies compared to those of the CpCo com-
plex 3. Like 6, compound 7 is also stable in solution
and does not react to a Co(CN)(4-C6H4Me) isomer.
1
determined by H-NMR spectroscopy. Fig. 1 shows a
series of spectra which illustrate the decrease in concen-
tration of 2 and the increase in concentration of 4 in
C6D6 at room temperature. The most characteristic
signals are those of the C5H5 protons at l 4.75 (for 2)
and 4.15 (for 4), of the benzylic CH2 protons at l 4.32

H. Werner et al. / Journal of Organometallic Chemistry 562 (1998) 45–51
47
Scheme 2.
(for 2) and 2.67 and 2.53 (for 4), and of the PMe3
protons at l 1.03 (for 2) and 0.93 (for 4), respectively.
The plot shown in Fig. 2 reveals that the isomeriza-
tion of 2 to 4 follows first-order kinetics. In C6D6 as the
solvent, the rate constant k (Table 1) is almost indepen-
dent of the presence of free PMe3 and 1.3-C6H8, which
indicates that in the rate-determining step a dissociation
of the Co–PMe3 bond does not occur and that radical
intermediates are probably not involved [7]. The addi-
tion of ca. 15 equiv of CH3OH to a solution of 2 in
C6D6 leads to an increase of the rate constant by a
factor of 2, which is consistent with the result that in
methanol-d4 as the solvent the rearrangement of 2 to 4
is about 10 times faster (at 25°C) than in C6D6. In
acetone-d6, the rate of the reaction is between that in
C6D6 and CD3OD, in agreement with the difference in
polarity of the three solvents.
plex [C5Me5Co(CNCH2Ph)(PMe3)] is formed which
readily undergoes N–C bond cleavage to give 8. The
significantly greater rate of formation of 8 compared to
4 is probably due to the presence of the strong donor
ligand C5Me5 which could stabilize a positive charge at
the cobalt in the transition state much better than the
unsubstituted C5H5 unit. With regard to the clean and
quantitative formation of 4 from 2 it should be noted
that various examples for the conversion of an iso-
cyanide- to a cyano-metal compound are known [8] but
in none of these reactions is the cleavage of the N–C
bond accompanied by the generation of a new M–C
linkage.
2.3. Preparation of C,C-bound and N,C-bound
ketenimine cobalt complexes
The relatively small difference in the rate constant k
Since we found that compound 2 reacts with phenyl-
or 4-tolylazide to give carbodiimide cobalt derivatives
[4], we were interested to find out whether related
ketenimine cobalt complexes were accessible on a simi-
lar route. While on treatment of 2 with PhCHN2 or
PhC(Me)N2 only decomposition of the diazoalkane oc-
curs, the reaction of 2 with Ph2CN2 in acetone leads to
a mixture of 4 and 9 (Scheme 4) with the latter as the
dominating species. Upon fractional crystallization
from ether, the ketenimine complex 9 was isolated as a
brown, moderately air-sensitive solid in ca. 30% yield.
The dihapto coordination of the Ph2CꢀCꢀNCH2Ph li-
gand via both carbon atoms of the cumulene chain,
which is already indicated by the strong CꢀCꢀN
stretching frequency at 1695 cm−1 in the IR spectrum,
is particularly supported by the NMR spectroscopic
data. The 13C-NMR spectrum of 9 displays the signals
of the ketenimine carbon atoms ꢀCꢀ and CPh2 at l
208.7 and 11.4 which is in agreement with the data of
other C,C-bound ketenimine metal derivatives [3,9].
The 4-tolylisocyanide complex 6 also reacts smoothly
with diphenyldiazomethane but in this case only the
ketenimine compound 10 (Scheme 4) is formed. On the
basis of the IR and NMR spectroscopic data there is no
(and the half-life time t1) for runs I, V and VI also rules
2
out that in the rate-determining step ionic intermediates
or ion-pairs such as [C5H5Co(CN)(PMe3)+PhCH2−]
would be formed. Therefore, the most reasonable pro-
posal for the mechanism of the isomerization of 2 to 4
is that an intramolecular oxidative addition occurs
leading to the preservation of the Co–CN and the
simultaneous formation of the new Co–CH2Ph bond.
In the transition state of the dissociative process possi-
bly a l+charge at the cobalt and a l−charge at the
benzylic CH2 carbon atom is generated which could
explain the small increase in the rate by going from
C6D6 (run I) to acetone-d6 (run V) and methanol-d4
(run VI). As far as the reaction of 5 and CNCH2Ph is
concerned, we assume that initially the isocyanide com-
Scheme 3.

48
H. Werner et al. / Journal of Organometallic Chemistry 562 (1998) 45–51
Fig. 1. 1H-NMR spectra for the rearrangement of 2 to 4 in C6D6 (run I) at 25°C at different times.
doubt that the complexes 9 and 10 are structurally quite
similar and that in the product which is initially gener-
ated from 6 and Ph2CN2 the ketenimine ligand
Ph2CꢀCꢀNTol is coordinated via both carbon atoms.
However, if a solution of 10 in benzene is heated at
50°C or irradiated with a UV lamp, a slow rearrange-
ment to the N,C-bound isomer 11, accompanied by
partial decomposition of the starting material, takes
place. The isomerization is facilitated in the presence of
CH3I, possibly due to a reversible addition of the alkyl
halide to the ketenimine unit. Under these conditions,
the isolated yield of 11 (which is a brown–orange solid)
is 82%. The main differences in the spectroscopic data
of isomers 10 and 11 are the w(CꢀCꢀN) frequency in the
IR spectrum, which for 11 is shifted by 65 cm−1 to
lower wave numbers compared to 10, the chemical shift
of the signal of the PCH3 protons in the 1H-NMR
spectrum (10: l 0.17; 11: l 0.65), and most significantly
the position of the resonances of the ketenimine carbon
atoms in the 13C-NMR spectrum. While for 10, these
signals appear at l 212.7 and 11.2 as doublets, they are
found at l 161.2 (CꢀCPh2) and 110.0 (CꢀCPh2) in the
spectrum of 11, the latter resonance showing no P–C
coupling. For a related ketenimine cobalt complex, of
which the structure had been determined by X-ray
crystallography, similar data were observed [3]. With
regard to the mechanism of the isomerization of 10 to
11, we assume that like for corresponding allene metal

H. Werner et al. / Journal of Organometallic Chemistry 562 (1998) 45–51
49
Scheme 4.
Fig. 2. Plot of -ln[2] vs time for the rearrangement of 2 to 4 in
different solvents (I: in C6D6; V: in acetone-d6; VI: in methanol-d4).
3.1. Preparation of [C5H5Co(CNCH2Ph)2] (3)
compounds [10] a slippage of the ketenimine unit along
the NꢀCꢀC chain occurs which is driven by the steric
requirements of the spectator ligands (C5H5 and PMe3)
and the aryl substituents of the Ph2CꢀCꢀNTol moiety.
In particular, in isomer 11 the steric hindrance between
the phenyl groups at the terminal carbon atoms of the
ketenimine and the cyclopentadienyl ring seems to be
reduced which would be consistent with the higher
thermodynamic stability of this species.
A solution of 336 mg (1.22 mmol) of 1 in 10 ml of
benzene was treated with 3.70 ml of a 0.66 M solution
(2.44 mmol) of CNCH2Ph in benzene at room temper-
ature. A gradual change of color from dark-brown to
red–brown occurred. After the solution was stirred
for 5 min, the solvent was removed in vacuo and the
oily residue was extracted with 20 ml of ether. The
extract was filtered, the filtrate was concentrated to ca.
5 ml in vacuo, and then 5 ml of pentane was added.
Storing the solution at −78°C for 12 h led to the
formation of a brown, extremely air-sensitive solid.
Yield 315 mg (72%). IR (C6H6): w(CꢁN) 2093, 1970,
3. Experimental section
1935 cm−1 1H-NMR (60 MHz, C6D6): l 7.18–6.88
.
All reactions were carried out under argon and in
carefully dried solvents. The starting materials
[C5R5Co(PMe3)2] (1, 5) were prepared as described in
the literature [11,12]; a preparative procedure for com-
pound 2 was already given [4]. IR: Perkin-Elmer 1420;
NMR: Varian EM 360 L, Jeol FX 90 Q, Bruker AMX
400. Melting and decomposition points were deter-
mined by DTA.
(m; 10H; C6H5), 4.93 (s; 5H; C5H5), 4.11 (s, 4H,
NCH2).
3.2. Preparation of [C5H5Co(CN)(CH2Ph)(PMe3)] (4)
A solution of 210 mg (0.66 mmol) of 2 in 5 ml of
benzene was stirred for 12 h at room temperature.
The solvent was removed in vacuo, and the oily
residue was recrystallized from benzene/pentane (1:5)
to give orange, only slightly air-sensitive crystals.
Yield 174 mg (83%); dec. temp. 106°C. Anal. Found:
C, 60.77; H, 6.79; N, 4.36. Calc. for C16H21CoNP: C,
Table 1
Rate constants k (at 2591°C), half-life times t1 and correlation
coefficients r2 for the reaction of 2 to 4 (run I: 22 in C6D6; run II:
2+10 equiv of PMe3 in C6D6; run III: 2+1 equiv of 1.3-C6H8 in
C6D6; run IV: 2+15 equiv of CH3OH in C6D6; run V: 2 in actone-d6;
run VI: 2 in methanol-d4)
60.57; H, 6.67; N, 4.42. IR (KBr): w(CꢁN) 2082 cm−1
.
1H-NMR (90 MHz, C6D6): l 7.77–7.06 (m; 5H;
C6H5), 4.15 (s; 5H; C5H5), 2.67 and 2.53 (both dd;
J(PH)=7.7 and 6.6, J(HH)=7.2 Hz, AB part of an
ABX system; 2H; CoCH2), 0.93 (d; J(PH)=10.6 Hz;
9H; PMe3). 13C-NMR (100.6 MHz, C6D6): l 154.2 (d;
J(PC)=3.9 Hz; ipso-C of C6H5), 128.5, 128.4 and
123.7 (all s; C6H5), 88.6 (d; J(PC)=1.0 Hz; C5H5),
17.1 (d; J(PC)=31.1 Hz; PCH3), 10.2 (d; J(PC)=
18.8 Hz; CoCH2), signal of CN carbon atom not ex-
actly located.
k [s−1
]
t1 [min]
r2
2
I
II
III
IV
V
6.29×10−5
5.21×10−5
5.99×10−5
1.22×10−4
1.30×10−4
6.71×10−4
184
222
193
95
89
17
0.999
1.000
0.992
0.997
0.999
0.997
VI

50
H. Werner et al. / Journal of Organometallic Chemistry 562 (1998) 45–51
3.3. Preparation of [C5H5Co(CNTol)(PMe3)] (6)
C5Me5), 15.3 (d; J(PC)=28.5 Hz; PCH3), 12.4 (d;
J(PC)=18.8 Hz; CoCH2), 9.5 (s; C5(CH3)5).
A solution of 700 mg (2.53 mmol) of 1 in 10 ml of
benzene was treated with 3.3 ml of a 0.77 M solution
(2.53 mmol) of CNTol in pentane at room temperature.
A quick change of color from dark-brown to red
occurred. After the solution was stirred for 5 min, the
solvent was removed in vacuo and the oily residue was
extracted with 10 ml of pentane. Storing the extract for
12 h at −78°C gave an orange, very air-sensitive solid.
Yield 660 mg (82%); dec. temp. 34°C. Anal. Found: C,
60.73; H, 6.73; N, 4.59. Calc. for C16H21CoNP: C,
3.6. Preparation of
[C5H5Co(s2-C,C-Ph2CꢀCꢀNCH2Ph)(PMe3)] (9)
A solution of 350 mg (1.10 mmol) of 2 in 15 ml of
acetone was treated with a solution of 214 mg (1.10
mmol) of Ph2CN2 in 5 ml of acetone at −78°C. After
the solution was warmed to room temperature, it was
stirred for 4 h and then the solvent was removed in
vacuo. The residue was washed with 10 ml of pentane
and subsequently extracted with 20 ml of ether. The
extract was concentrated to ca. 10 ml in vacuo and
after it was stored for 12 h at −78°C a brown solid
60.57; H, 6.67; N, 4.42. IR (C6H6): w(CꢁN) 1825 cm−1
.
1H-NMR (90 MHz, C6D6): l 7.18 and 6.85 (both d;
J(HH)=8.2 Hz; 2H each; C6H4), 4.77 (d; J(PH)=1.2
Hz; 5H; C5H5), 2.02 (s; 3H; C6H4CH3), 1.10 (d;
J(PH)=9.2 Hz; 9H; PMe3).
1
was formed. Due to the H-NMR spectrum, it consists
of a 3:2 mixture of 9 and 4. The solid was separated,
the mother liquor was filtered, and the filtrate was
concentrated to ca. 2 ml in vacuo. Cooling the concen-
trate to −78°C led to the formation of brown crystals,
which were separated, washed with small portions of
pentane (−20°C) and dried. Yield 153 mg (29%); dec.
temp. 132°C. Anal. Found: C, 72.33; H, 6.89; N, 3.04.
Calc. for C29H31CoNP: C, 72.04; H, 6.46; N, 2.90: IR
3.4. Preparation of [C5Me5Co(CNTol)2] (7)
A solution of 529 mg (1.53 mmol) of 5 in 15 ml of
ether was treated with 3.48 ml of a 0.88 M solution
(3.06 mmol) of CNTol in pentane at 0°C. An immedi-
ate change of color from dark-brown to red occurred.
The solution was worked-up as described for 6 to give
red, extremely air-sensitive crystals. Yield 544 mg
(83%); dec. temp. 68°C. Anal. Found: C, 74.02; H, 6.18;
N, 6.27. Calc. for C26H29CoN2: C, 72.88; H, 6.82; N
(C6H6): w(CꢀCꢀN) 1695 cm−1 1H-NMR (90 MHz,
.
C6D6): l 7.97–6.77 (m; 15H; C6H5), 5.53 and 5.33
(both d; J(HH)=14.8 Hz; 1H each; NCH2), 4.27 (d;
J(PH)=1.0 Hz; 5H; C5H5), 0.32 (d; J(PH)=8.9 Hz;
9H; PMe3). 13C-NMR (100.6 MHz, C6D6): l 208.7 (d;
J(PC)=18.3 Hz; CoCN), 152.1 (d; J(PC)=1.9 Hz;
ipso-C of C6H5), 146.4 (d; J(PC)=3.5 Hz; ipso-C of
C6H5), 142.7 (s; ipso-C of C6H5), 129.8, 129.7, 129.1,
128.8, 128.2, 127.2, 126.8, 125.4 and 123.0 (all s; C6H5),
85.1 (d; J(PC)=1.5 Hz; C5H5), 64.4 (d; J(PC)=2.5
Hz; NCH2), 19.2 (d; J(PC)=28.2 Hz; PCH3), 11.4 (d;
J(PC)=3.4 Hz; CoCPh2).
1
6.54. IR (C6H6): w(CꢁN) 2063, 2032, 1920 cm−1. H-
NMR (90 MHz, C6D6): l 7.00 and 6.68 (both d;
J(HH)=7.8 Hz; 4H each; C6H4), 2.03 (s; 15H; C5Me5),
1.90 (s; 6H; C6H4CH3). 13C-NMR (100.6 MHz, C6D6):
l 190.4 (s; CoCN), 134.8, 131.8, 130.0 and 124.6 (all s;
C6H4), 93.9 (s; C5Me5), 21.0 (s; C6H4CH3), 11.2 (s,
C5(CH3)5).
3.5. Preparation of [C5Me5Co(CN)(CH2Ph)(PMe3)] (8)
3.7. Preparation of
A solution of 566 mg (1.63 mmol) of 5 in 10 ml of
ether was treated at 0°C with 1.92 ml of a 0.85 M
solution (1.63 mmol) of CNCH2Ph in benzene. After
the solution was stirred for 2–3 min, the solvent was
removed in vacuo and the oily residue was extracted
with 10 ml of ether. The extract was filtered and the
filtrate was concentrated to ca. 5 ml in vacuo. Storing
the solution at −78°C for 12 h led to the formation of
orange, only slightly air-sensitive crystals. Yield 467 mg
(74%); dec. temp. 82°C. Anal. Found: C, 65.24; H, 8.42;
N, 3.69. Calc. for C21H31CoNP: C, 65.11; H, 8.07; N,
[C5H5Co(s2-C,C-Ph2CꢀCꢀNTol)(PMe3)] (10)
Compound 10 was prepared as described for 9 start-
ing from 517 mg (1.63 mmol) of 6 and 317 mg (1.63
mmol) of Ph2CN2. The reaction time was 7 h. Upon
recrystallization of the oily residue from benzene/pen-
tane (1:4) a brown–orange solid was obtained. Yield
374 mg (47%); dec. temp. 134°C. Anal. Found: C,
71.59; H, 6.55; N, 3.23. Calc. for C29H31CoNP: C,
72.04; H, 6.46; N, 2.90. IR (C6H6): w(CꢀCꢀN) 1660
cm−1 1H-NMR (90 MHz, C6D6): l 7.98–6.87 (m;
.
3.62. IR (C6H6): w(CꢁN) 2091 cm−1
.
1H-NMR (90
14H; C6H5 and C6H4), 4.33 (d; J(PH)=1.0 Hz; 5H;
C5H5), 2.27 (s; 3H; C6H4CH3), 0.17 (d; J(PH)=9.4 Hz;
9H; PMe3). 13C-NMR (100.6 MHz, C6D6): l 212.7 (d;
J(PC)=22.1 Hz; CoCN), 152.6 (d; J(PC)=1.5 Hz;
ipso-C of C6H5), 151.0 (d; J(PC)=2.6 Hz; ipso-C of
C6H5), 133.2, 129.4, 128.4, 127.2, 125.6, 123.1 and 122.3
(all s; C6H5 and C6H4), 86.5 (d; J(PC)=1.3 Hz; C5H5),
MHz, C6D6): l 7.78–7.07 (m; 5H; C6H5), 2.49 (d;
J(PH)=6.7 Hz; 2H; CoCH2), 1.25 (d; J(PH)=1.5 Hz;
15H; C5Me5), 0.89 (d; J(PH)=9.8 Hz; 9H; PMe3).
13C-NMR (100.6 MHz, C6D6): l 151.7 (d; J(PC)=2.5
Hz; ipso-C of C6H5), 138.2 (d; J(PC)=37.8 Hz;
CoCN), 130.4, 127.9 and 123.7 (all s; C6H5), 95.0 (s;

H. Werner et al. / Journal of Organometallic Chemistry 562 (1998) 45–51
51
21.1 (s; C6H4CH3), 18.6 (d; J(PC)=28.5 Hz; PCH3),
11.2 (s, br; CoCPh2).
relaxation delay RD): ~=D1+NS(AQ+RD), where
~=tn−tn−1. For all measurements the temperature
was 2591°C.
3.8. Preparation of
[C5H5Co(s2-C,N-Ph2CꢀCꢀNTol)(PMe3)] (11)
Acknowledgements
A solution of 80 mg (0.17 mmol) of 10 in 10 ml of
benzene was stirred, in the presence of 10 vl (0.16
mmol) of CH3I, for 16 h at room temperature. The
volatile components were removed in vacuo and the
oily residue was recrystallized from ether/pentane (1:3).
Upon storing the solution at −78°C, brown–orange
crystals were obtained. Yield 66 mg (82%); dec. temp.
65°C. Anal. Found: C, 72.30; H, 6.74; N, 2.78. Calc. for
C29H31CoNP: C, 72.04; H, 6.46; N, 2.90. IR (KBr):
We thank the Volkswagen Stiftung for financial sup-
port and NATO (Grant No. CRG 910299) for travel
expenses. We also gratefully acknowledge support by
C.P. Kneis and R. Schedl (elemental analysis and DTA
measurements) and Dr W. Buchner (NMR spectra).
References
1
w(CꢀCꢀN) 1630 cm−1. H-NMR (90 MHz, C6D6): l
[1] Review: H. Werner in: A. de Meijere, H. tom Dieck (Eds.),
Organometallics in Organic Synthesis , Springer, Berlin, 1987, pp
51–67.
[2] Recent work: (a) B. Strecker, B. Zeier, M. Schulz, J. Wolf, H.
Werner, Chem. Ber. 123 (1990) 1787. (b) H. Werner, B. Strecker,
J. Organomet. Chem. 413 (1991) 379. (c) B. Zeier, Dissertation,
Universita¨t Wu¨rzburg, 1992. (d) Liu Xiaolan, Dissertation, Uni-
versita¨t Wu¨rzburg, 1992. (e) G. Ho¨rlin, Dissertation, Universita¨t
Wu¨rzburg, 1993.
[3] (a) B. Strecker, H. Werner, Angew. Chem. 102 (1990) 310;
Angew. Chem. Int. Ed. Engl. 29 (1990) 275. (b) B. Strecker, G.
Ho¨rlin, M. Schulz, H. Werner, Chem. Ber. 124 (1991) 285.
[4] G. Ho¨rlin, N. Mahr, H. Werner, Organometallics 12 (1993)
1775.
[5] B. Heiser, Dissertation, Universita¨t Wu¨rzburg, 1983.
[6] H. Yamazaki, N. Hagihara, J. Organomet. Chem. 21 (1970) 431.
[7] The 1H-NMR spectra of run III don’t display the signals of
toluene, which should be generated from benzyl radicals and
1.3-C6H8; see: J.W. Wilt in: J.K. Kochi (Ed.), Free Radicals, vol.
1, Wiley, New York, 1973, p. 405.
[8] (a) L. Tschugaeff, P. Teearu, Chem. Ber. 47 (1914) 2643. (b)
W.Z. Heldt, J. Inorg. Nucl. Chem. 24 (1962) 265. (c) P.M.
Treichel, R.W. Hess, J. Chem. Soc. Chem. Commun. (1970)
1626. (d) B. Crociani, M. Nicolini, R.L. Richards, Inorg. Chim.
Acta 12 (1975) 53. (e) C.M. Giandomenico, L.H. Hanau, S.J.
Lippard, Organometallics 1 (1982) 142. (f) A. Bell, S.J. Lippard,
M. Roberts, R.A. Walton, Organometallics 2 (1983) 1562. (g)
S.M. Terrick, R.A. Walton, Inorg. Chem. 24 (1985) 3363. (h)
J.P. Farr, M.J. Abrams, C.E. Costello, A. Davison, S.J. Lippard,
A.G. Jones, Organometallics 4 (1985) 139. (i) W.D. Jones, W.P.
Kosar, Organometallics 5 (1986) 1823. (j) G. Poszmik, P.J.
Carroll, B.B. Wayland, Organometallics 12 (1993) 3410.
[9] A. Ho¨hn, H. Werner, Chem. Ber. 121 (1988) 881.
[10] (a) R. Ben-Shoshan, R. Pettit, J. Am. Chem. Soc. 89 (1967)
2231. (b) K. Vrieze, H.C. Volger, A.P. Praat, J. Organomet.
Chem. 21 (1970) 467.
7.86–6.88 (m; 14H; C6H5 and C6H4), 4.28 (s; 5H;
C5H5), 2.01 (s; 3H; C6H4CH3), 0.65 (d; J(PH)=10.0
Hz; 9H; PMe3). 13C-NMR (100.6 MHz, C6D6): l 161.2
(d; J(PC)=18.4 Hz; CoCN), 150.2 and 145.4 (both s;
ipso-C of C6H5), 139.8 (d; J(PC)=2.6 Hz; ipso-C of
C6H4), 132.1, 130.5, 129.6, 129.5, 129.4, 129.2, 128.1,
127.9, 127.2, 126.6, 125.6, 124.3, 124.1, 123.3 and 122.3
(all s; C6H5 and C6H4), 110.0 (s; CPh2), 84.0 (d;
J(PC)=2.0 Hz; C5H5), 21.1 (s; C6H4CH3), 16.6 (d;
J(PC)=27.4 Hz, PCH3).
3.9. Kinetic studies
The rate measurements for the reaction of 2 to 4 were
carried out with samples of 2, which were recrystallized
three times from pentane. The samples (5–20 mg) were
dissolved under argon in a Glove box in an appropriate
amount of C6D6, acetone-d6 or methanol-d4 to give
0.006–0.011 M solutions. For run II (see Table 1) ca.
10 equiv of PMe3, for run III ca. one equiv of 1.3-C6H8,
and for run IV ca. 15 equiv of CH3OH were added.
Each solution was transfered to an NMR tube (5 mm
diameter), which was kept at −190°C and then sealed.
Immediately after the tube was brought to room tem-
perature, the NMR spectra were recorded. The kinetics
were studied using a Bruker automation program im-
plemented on a Bruker AC 200 NMR spectrometer.
The delay between two consecutive data accumulations
was set (D1) and the spectra were stored automatically.
The total time increment between two measurements
was the sum of the set delay D1 and the product of the
number of scans (NS) and the aquisition time (AQ plus
[11] H. Werner, W. Hofmann, Chem. Ber. 110 (1977) 3481.
[12] H. Werner, B. Heiser, B. Klingert, R. Do¨lfel, J. Organomet.
Chem. 204 (1982) 179.
.
.