Synthesis and structural characterization of organometallic cyclynes: Novel nanoscale, carbon-rich topologies

Article abstract of DOI:10.1016/S0022-328X(03)00145-1

A combination of Pd- and Cu-catalyzed couplings make the ferrocene and cyclobutadiene(cyclopentadienylcobalt)-based half-wheels and the cyclobutadiene(cyclopentadienylcobalt)-based seco-wheel accessible. These targets can formally be constructed by fusing two or three organometallic benzohexadehydro[14]annulenes along an alkyne unit. In addition, a ferrocene-based, enlarged version of the half wheel was prepared. This target compound is obtained by formally fusing two organometallic benzododecadehydro[18]annulenes. Single crystal structures of three target molecules, the cyclobutadiene complex C 51 H 37 Co, the ferrocene derivative C 51 H 36 Fe, and the cyclobutadiene complex C 69 H 59 Co were performed to verify the proposed geometries.

Full text of DOI:10.1016/S0022-328X(03)00145-1

Journal of Organometallic Chemistry 673 (2003) 25Á39
/
www.elsevier.com/locate/jorganchem
Synthesis and structural characterization of organometallic cyclynes:
novel nanoscale, carbon-rich topologies
Matthew Laskoski, Winfried Steffen, Jason G.M. Morton, Mark D. Smith,
Uwe H.F. Bunz *
Department of Chemistry and Biochemistry and The USC NanoCenter, The University of South Carolina, Columbia, SC 29208, USA
Received 30 January 2003; received in revised form 26 February 2003; accepted 26 February 2003
Abstract
A combination of Pd- and Cu-catalyzed couplings make the ferrocene and cyclobutadiene(cyclopentadienylcobalt)-based half-
wheels and the cyclobutadiene(cyclopentadienylcobalt)-based seco-wheel accessible. These targets can formally be constructed by
fusing two or three organometallic benzohexadehydro[14]annulenes along an alkyne unit. In addition, a ferrocene-based, enlarged
version of the half wheel was prepared. This target compound is obtained by formally fusing two organometallic
benzododecadehydro[18]annulenes. Single crystal structures of three target molecules, the cyclobutadiene complex C51H37Co, the
ferrocene derivative C51H36Fe, and the cyclobutadiene complex C69H59Co were performed to verify the proposed geometries.
# 2003 Published by Elsevier Science B.V.
Keywords: Alkynes; Dehydro[14]annulenes; Dehydro[18]annulenes; Cyclobutadiene complexes; Cobalt; Pd-catalysis; Copper
1. Introduction
sensitivity of the involved and projected species but as
well due to the increased synthetic effort to make them.
Alkynylated p-systems have attracted significant at-
That, however, has changed [10Á15] and particularly
/
Gladysz’s [12] recent spectacular work on ‘‘wrapped’’
carbon rods has enhanced the visibility of this area
dramatically.
tention during the last decade [1Á9]. Their relation to
/
dendrimers, fullerenes, and carbon nanotubes have
made carbon rich materials an exciting area of research.
Consequently, in recent years almost all conceivable
peralkynylated p-perimeters have been prepared. Highly
alkynylated modules have multiple applications [1] as
precursors to novel aromatic systems [2] as molecular
wires and as NLO active materials. A spectacular
development in this field was Vollhardt’s [3] discovery
of a shortcut from dehydroannulenes to carbon nano-
materials, demonstrated by the explosive decomposition
of a large non-planar dehydroannulene. The authors
found well-developed nanotubes and fullerene-type
We have a long standing commitment in carbon rich
organometallics [14], we have developed the area of
highly alkynylated cyclobutadiene complexes. These are
building blocks for nanoscale organometallic topologies
and unusual conjugated organometallic polymers. In
this contribution we report details of the synthesis and
structural characterization of four novel organometallic
cyclynes [10] with an expanded bicyclo[1.1.0]butane (A)
and a tricyclo[2.1.0.01,3]pentane (B) topology. In these
structures. While the organic arm (vide infra) [1Á9] of
/
carbon rich is strong, their organometallic relatives used
to be less popular not only because of the perceived
structures, the Cꢀ
/
C-single bonds of the small rings are
* Corresponding author. Present address: School of Chemistry and
Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-
replaced by alkyne or butadiyne bridges, while the
carbon atoms are substituted by benzene rings, cyclo-
butadiene(cyclopentadienyl)cobalt units or ferrocene
0400, USA. Tel.: ꢀ
/
1-404-385-1795; fax: ꢀ1-803-929-0267.
/
E-mail address: uwe.bunz@chemistry.gatech.edu (U.H.F. Bunz).
0022-328X/03/$ - see front matter # 2003 Published by Elsevier Science B.V.
doi:10.1016/S0022-328X(03)00145-1

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M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á39
/
nuclei. Key steps in the synthesis of these targets are the
selective ortho-metalation of organometallic acetals,
[14], the conversion of aldehydes into alkynes by the
Ohira method, [16] and Cu-catalyzed dimerizations of
terminal alkynes [17].
To show the general applicability of the method, the
ferrocene-containing ‘‘super-bicyclo[1.1.0]butane’’ 12
was targeted. The diyne 8 was reacted with 5a under
Pd-catalysis (Scheme 2) to furnish 9 in 79% yield.
Deketalization with TsOH followed by Ohira alkynyla-
tion transforms 9 into the pentayne 10 in 80%. The
critical step is the Pd-catalyzed coupling of 10 to 2b that
furnishes 11 in 24%. The yield of the coupling is only
moderate, again due to the decrease in reactivity the
iodide 2b experiences as a consequence of being posi-
tioned between two alkyne substituents. Deprotection of
11 and double cyclization using Cu(OAc)2 in acetonitrile
[17] gives 12 in 61% as dark red, stable needles.
It was of interest if a ‘‘super-tricyclic’’ structure
analogous to B was accessible by this method. A
retrosynthetic analysis suggests 13 [14c] as starting point
for 17 (Scheme 3). Pd-catalyzed coupling of 13 to 5b
formed 14 in 59% yield. Deprotection by TsOH and
conversion of the two aldehyde groups into alkyne units
commenced under standard conditions [16] to give 15 in
80%. The critical step is the double Pd-catalyzed
coupling of 15 to 2a that provided 16 in 17% after
deprotection with Bu4NꢀFꢁ in THF. The last step in
the reaction sequence is the triple ring closure to 17 that
2. Results and discussion
Pd-catalyzed coupling of 1 [14c,d] to the iodide 2a
furnishes 3 in 23% (Scheme 1). The moderate yield of 3
is a result of the two meta-positioned alkyne groups in
2a between which the iodide is sandwiched. Only the
active Hartwig-catalyst [(o-tolyl)3P]2Pd [18] with THF
as co-solvent [19] is capable of coupling 1 to 2a. The
coupling product 3 was deketalized by para-toluenesul-
fonic acid (TsOH) and reacted with the OhiraÁ
/Seyferth
reagent [CH3CꢁOCN2ꢀPꢁO(OEt)2] [16] to give the
/
/
/
pentayne 4 in 81%. Coupling of 4 to 5 furnishes 6 in
70%. Desilylation of 6 commences with Bu4NF in THF;
the intermediate heptayne was immediately utilized for
the coupling step to close the two cyclyne rings to form 7
in 71% yield. The six-step synthesis (10
/7) proceeds in a
respectable overall 9% yield.
Scheme 1. (a) (o-tolyl3P)2PdCl2, CuI, NEt3, THF, 24 8C, 12 h; (b) para-toluenesulfonic acid, THF, 24 8C, 12 h; (c) K2CO3, 24 8C, 8 h; (d)
(PPh3)2PdCl2, CuI, piperidine, THF, 24 8C, 12 h; (e) tetrabutylammonium fluoride, THF, 24 8C, 1 h; (f) Cu(OAc)2, CH3CN, 80 8C, 8 h.

M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á
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27
Scheme 2. (a) (o-tolyl3P)2PdCl2, CuI, NEt3, THF, 24 8C, 12 h; (b) para-toluenesulfonic acid, THF, 24 8C, 12 h; (c) K2CO3, 24 8C, 8 h; (d)
(PPh3)2PdCl2, CuI, piperidine, THF, 24 8C, 12 h; (e) tetrabutylammonium fluoride, THF, 24 8C, 1 h; (f) Cu(OAc)2, CH3CN, 80 8C, 8 h.
proceeds in 25% yield. Significant amounts of insoluble
and infusible tan-colored solids are formed as bypro-
ducts. The relatively low yield of this transformation is a
consequence of the underlying statistics of the ring
closing reaction. If in 16 the alkynes of benzene units
1 and 4 couple, 17 cannot form. Instead crosslinking to
insoluble materials prevails. If the ring closing reaction
proceeds statistically, it is expected to lose 33% of 16 to
the unwanted cyclizations, i.e. the highest possible
reaction yield is 67%. The actual yield of 25% suggests
that each ring forms in a satisfactory yield of 72%, if the
unproductive coupling paths are corrected for by a
simple statistical analysis.
acetonitrile to furnish the doubly closed and enlarged
half wheel 24 in 18% yield as orange, sensitive solid that
was characterized by its NMR data. Attempts to obtain
single crystalline specimens of 24 were not successful.
Instead microcrystalline powders resulted.
The novel and intriguing structures of the organome-
tallic super-bicyclo[1.1.0]butanes 7, 12, and the super-
tricyclo[2.1.0.01,3]pentane 17 mandated their single crys-
tal structure analysis. Suitable, coffin-shaped specimens
were obtained from mixtures of dichloromethane and
hexanes.
ORTEP-representations of 7, 12 and 17, and packing
diagrams of 12 and 17 are shown in Figs. 1Á6. The bond
/
lengths and bond angles of 7, 12 and 17 are in excellent
agreement with reported values for alkynylated cyclo-
butadiene and cyclopentadienyl complexes [14,20]. The
polyyne 7 forms a perfect half-wheel. The three radial
alkyne units attached to the cyclobutadiene complex are
linear. The butadiyne groupings are moderately bent to
accommodate the topological necessities of the structure
(Fig. 1). The surrounding of the cyclobutadiene complex
is considerably less non-planar than expected for multi-
ply ethynylated complexes of this type, [14,20] and this
It was interesting to see if the concept could be
expanded to a larger ferrocene containing half wheel. In
Scheme 4, the synthesis of such a half wheel is shown.
Starting from 8 CadiotÁChodeiewicz coupling to 19
/
furnished 20 in 46% yield. Deketalization is followed by
an Ohira reaction to give the alkyne 21 in 58%, which in
a second CadiotÁChodkiewicz coupling with 22 is
/
transformed into the decayne 23 in a yield of 24%.
Deprotection with tetrabutylammoniumfluoride is fol-
lowed by a Vogtle coupling [17] utilizing Cu(OAc) in
¨
2

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M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á39
/
Scheme 3. (a) (o-tolyl3P)2PdCl2, CuI, NEt3, THF, 24 8C, 12 h; (b) para-toluenesulfonic acid, THF, 24 8C, 12 h; (c) K2CO3, 24 8C, 8 h; (d)
(PPh3)2PdCl2, CuI, piperidine, THF, 24 8C, 12 h; (e) tetrabutylammonium fluoride, THF, 24 8C, 1 h; (f) Cu(OAc)2, CH3CN, 80 8C, 8 h.
effect may be a consequence of the direct interconnec-
tion of the three alkyne substituents by a network of
cyclyne rings.
The structure of the open congeners of 17, the
butterfly 18, has recently been described [14]. In these
species the alkyne bridges are bent away from the
cyclobutadiene nucleus to accommodate for the electro-
nic influence of the cyclopentadienylcobalt fragment. It
was of interest if in the polyyne 17 the same distortion
was visible. A suitable specimen was obtained from
The ferrocene-based cyclyne 12 (Fig. 2) experiences
significant in-plane bending of the outer two of the three
radial alkyne units, leading to a slight ruffling of the
large hydrocarbon ligand (Fig. 2a), similar to that
observed in some porphyrins [21]. This ruffling is caused
by the minor mismatch of the circumference of the
perimeter compared with the size of the radial spokes. It
bears testimony to the adaptation of the outer p-
perimeter to the decreased bond angles (728) prevalent
in the ferrocene module when compared with the square
cyclobutadiene complexes. The packing of 12 is remark-
able and shown in Fig. 3. Six molecules form a circular
triple helical arrangement that results in a fascinating
superstructure not observed in the packing of 7.
dichloromethaneÁhexane mixtures and an ORTEP repre-
/
sentation of 17 is shown in Fig. 4. The molecules of 17
are disordered in the crystal, but the large hydrocarbon
ligand is flattened out (Fig. 5) when compared with the
structure of the butterfly 18 [14g]. The flattening is
particularly pronounced in the backside of the large
ligand, where the third ring is closed. The full wheel of
the topology D is expected to be planar, due to the
geometric relationship of the perimeter to the length of the
radial spikes.

M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á
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29
Scheme 4. (a) BuLi, then CuI 15 min; (b) propylamine, 19, 22 8C, 1 h; (c) TsOH, 1 h 22 8C; (d) tetrabutylammonium fluoride, THF, 24 8C, 1 h; (e)
Cu(OAc)2, CH3CN, 80 8C, 8 h.
The packing of the seco-wheel 17 is similar to that of
18 insofar as both 17 and 18 are stacked parallel to each
other. However, Fig. 6 shows that stacks of the
molecules of 17 are oriented in a herringbone pattern
with respect to each other, making that packing motif
similar to structures observed for aromatic molecules.
The cyclopentadienylcobalt units are tucked into the
interlayer space of the columns. We investigated (Fig. 7)
the molecular structure of the compound 24 by semi-
empirical calculations (PM3 tm, implemented by wave-
function’s SPARTAN on a Windows 2000 platform). The
structure is virtually unstrained and the bond lengths
and bond angles are in excellent agreement with values
obtained from crystal structures of simpler model
compounds [14]. The large hydrocarbon ligand is flat
and the cyclopentadienyl ring in the ferrocene accom-
modates the bicyclic structure without any appreciable
strain.
In conclusion, a series of novel polycyclic carbon-rich
organometallics (7, 12, 17 and 24) has been prepared by
a combination of Ohira-alkynylations, Pdꢀ/Cu catalyzed
couplings, and Cu(OAc)2-mediated cyclizations. The
targets represent nanoscale versions of A and B; they
have been subjected to single crystal structure determi-
nation and show subtle differences in their structures
depending upon the central organometallic core. In

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M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á39
/
ether (50 ml). The combined organic layers were dried
over MgSO4 and the solvent was removed in vacuo.
Column chromatography (SiO2Á
/
hexanesꢀ10% NEt3)
/
furnished 3 (223 mg, 23%) as an orange, oily solid. IR
1
(cmꢁ1): n 2939, 2862, 2315, 2146, 1446, 1123, 992. H-
NMR (300 MHz, CDCl3): d 7.20 (s, 2H, aromatic-H),
5.02 (s, 5H, Cp-H), 5.01 (s, 2H, CH-acetal), 4.08 (s, 1H,
Cb-H), 4.14Á
4H, CH2-acetal), 2.50 (t, 2H, JH,H
CH2), 2.08Á
butyl-CH2), 1.36Á
(m, 2H, butyl-CH2), 1.13 (s, 42H, TIPS-H), 0.91 (t, 3H,
3JH,H 7.69 Hz, butyl-CH3). 13C-NMR (75 MHz,
/
4.03 (m, 4H, CH2-acetal), 3.82Á
/
3.65 (m,
3
ꢂ
/
7.69 Hz, butyl-
/
2.00 (m, 2H, CH2-acetal), 1.59Á/2.49 (m, 2H,
/
1.24 (m, 2H, CH2-acetal), 1.24Á
/1.15
ꢂ
/
CDCl3): d 141.90, 133.65, 126.24, 124.94 (aromatic-C),
106.31 (alkyne-C), 97.87 (acetal-CH), 94.72, 92.39, 87.59
(alkyne-C), 81.36 (Cp-C), 76.75 (Cb-C), 66.85 (acetal-
CH2), 55.36, 52.65 (Cb-C), 34.96, 33.07 (butyl-CH2),
25.86 (acetal-CH2), 22.25 (butyl-CH2), 18.84 (TIPS-
CH3), 13.84 (butyl-CH3), 11.40 (TIPS-CH). MS (EI)
m/z Calc. for [M]ꢀ (C52H77CoO4Si2) 880.4692. Found
Fig. 1. ORTEP representation of the molecular structure of 7.
880.4685 (Eꢂ1.2 ppm).
/
3.2. Synthesis of 4
A 50 ml round bottom flask was charged with 3 (100
mg, 0.122 mmol), TsOH (110 mg, 0.581 mmol) and wet
THF (5 ml). The resulting solution was stirred at
ambient temperature for 12 h before being quenched
with water and ethyl ether. The water layer was
separated and extracted with ethyl ether (50 ml). The
combined organic layers were dried over MgSO4 and the
solvent was removed in vacuo to yield a dark red oil. To
the oil in a 50 ml Schlenk flask was added K2CO3 (110
mg, 0.800 mmol), abs. THF (5 ml) and abs. methanol (5
ml) under nitrogen. After cooling to 0 8C, dimethyl-(1-
diazo-2-oxopropyl)phosphonate (110 mg, 0.568 mmol)
was added dropwise over 5 min. The resulting solution
was allowed to stir for 8 h before being quenched with a
saturated NaHCO3 solution (50 ml) and CH2Cl2. The
water layer was separated and extracted with CH2Cl2
(50 ml). The combined organic layers were dried over
MgSO4 and the solvent was removed in vacuo. Column
Fig. 2. ORTEP representation of 12.
future we will report the synthesis and characterization
of a full wheel with a nanoscale-topology of the
unknown fenestrane-type C [22,23].
3. Experimental
chromatography (SiO2Áhexanes:CH2Cl2, 9:1) furnished
/
4 (71.0 mg, 81%) as a darkÁ
orange oil. IR (cmꢁ1): n
/
3.1. Synthesis of 3
2915, 2861, 2323, 2146, 1692, 1453, 1000. 1H-NMR (300
MHz, CDCl3): d 7.23 (s, 2H, aromatic-H), 5.01 (s, 5H,
Cp-H), 4.47 (s, 1H, Cb-H), 3.01 (s, 2H, alkyne-H), 2.52
A 50 ml, oven-dried Schlenk flask was charged with 1
(410 mg, 1.10 mmol), [14c] CuI (12.0 mg, 0.062 mmol),
Pd(P(o-tol)3)2 (50.0 mg, 0.067 mmol), 4-iodo-3,5-(trii-
sopropylsilylethynyl)butylbenzene (2a) (800 mg, 1.28
mmol), and abs. THF (3 ml). The flask was flushed
with nitrogen and degassed Et3N (5 ml) was added. The
resulting solution was stirred at ambient temperature for
12 h before being quenched with water and ethyl ether.
The water layer was separated and extracted with ethyl
3
(t, 2H, JH,H
ꢂ
/
7.69 Hz, butyl-CH2), 1.59Á
1.16 (m, 2H, butyl-CH2), 1.13 (s, 42H,
TIPS-H), 0.92 (t, 3H, 3JH,H 7.69 Hz, butyl-CH3). 13C-
/
1.52 (m, 2H,
butyl-CH2), 1.22Á
/
ꢂ
/
NMR (75 MHz, CDCl3): d 142.65, 133.39, 126.41,
124.41 (aromatic-C), 105.63, 95.39, 90.48, 90.35 (alkyne-
C), 82.87 (Cp-C), 79.69, 79.62 (alkyne-C), 64.28, 61.95,
56.68 (Cb-C), 35.08, 33.08, 22.31 (butyl-CH2), 13.36
(butyl-CH3), 18.86 (TIPS-CH3), 11.36 (TIPS-CH). MS

M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á
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31
Fig. 3. Packing diagram of 12. Visible is the 6-fold axis in that the single molecules of 12 are packed in the solid state.
Fig. 5. ORTEP representation of 17, side view. Substituents are
removed for clarity.
mmol), and abs. THF (2 ml). The flask was flushed with
nitrogen and degassed piperidine (5 ml) was added. The
resulting solution was stirred at ambient temperature for
12 h before being quenched with water and ethyl ether.
The water layer was separated and extracted with ethyl
ether (50 ml). The combined organic layers were dried
over MgSO4 and the solvent removed in vacuo. Column
Fig. 4. ORTEP representation of 17.
(EI) m/z Calc. for [M]ꢀ (C47H61CoSi2) 740.3644. Found
740.3673 (Eꢂ3.7 ppm).
/
chromatography (SiO2Áhexanes:CH2Cl2, 4:1) furnished
/
6 (78.0 mg, 70%) as a dark orange oil. IR (cmꢁ1): n
2946, 2861, 2315, 2153, 1646, 1538, 1246, 1000. 1H-
3.3. Synthesis of 6
3
NMR (300 MHz, CDCl3): d 7.32 (d, 2H, JH,H
ꢂ8.23
/
4
Hz, aromatic-H), 7.27 (d, 2H, JH,H
ꢂ1.37 Hz, aro-
/
A 50 ml, oven-dried Schlenk flask was charged with 4
(71.0 mg, 0.100 mmol), CuI (0.9 mg, 0.005 mmol),
Cl2Pd(PPh3)2 (1.0 mg, 0.001 mmol), 4-iodo-3-(trimethyl-
silylethynyl)isopropylbenzene [2] (5a) (100 mg, 0.290
matic-H), 7.24 (s, 2H, aromatic-H), 7.04 (dd, 2H,
3JH,H
4
8.23 Hz, JH,H
ꢂ
/
ꢂ
/
1.37 Hz, aromatic-H), 5.03 (s,
2.77 (m, 2H,
5H, Cp-H), 4.59 (s, 1H, Cb-H), 2.86Á
/

32
M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á39
/
Fig. 6. Packing diagram of 17 in the solid state.
130.39, 126.86, 126.78, 125.14, 124.76, 124.46 (aromatic-
C), 105.88, 104.33, 97.79, 95.57, 91.91, 90.84, 90.42,
89.03 (alkyne-C), 83.03 (Cp-C), 64.84, 62.04, 58.98 (Cb-
C), 35.33 (butyl-CH2), 34.17 (isopropyl-C), 33.38 (butyl-
CH2), 23.83 (isopropyl-C), 22.56 (butyl-CH2), 19.04
(TIPS-CH3), 14.13 (butyl-CH3), 11.62 (TIPS-CH), 0.37
(TMS-C). MS (EI) m/z Calc. for [M]ꢀ (C75H97CoSi4)
1168.6. Found 1168.5.
3.4. Synthesis of 7
A 50 ml, round bottom flask was charged with 6 (78.0
mg, 0.071 mmol), Bu4NꢀFꢁ (0.35 ml, 1.0 M in THF)
and THF (2 ml). The resulting solution was stirred at
ambient temperature for 1 h before being quenched with
water and ethyl ether. The water layer was separated
and extracted with ethyl ether (50 ml). The combined
organic layers were dried over MgSO4 and the solvent
was removed in vacuo to yield a dark red oil. To the oil,
in a 100 ml round bottom flask, was added Cu(OAc)2
(300 mg, 1.65 mmol) and MeCN (50 ml). The resulting
solution was heated to 80 8C for 8 h. The solvent was
removed in vacuo, the resulting mixture redissolved in
Fig. 7. Semiempirical calculation (PM3) of the structure of 24. The
large hydrocarbon ligand is perfectly planar and the bond distances
and bond angles show the expected values.
3
isopropyl-CH), 2.53 (t, 2H, JH,H
ꢂ7.69 Hz, butyl-
/
CH2), 1.61Á
/
1.53 (m, 2H, butyl-CH2), 1.40Á
/
1.32 (m,
6.86 Hz, isopro-
3
2H, butyl-CH2), 1.19 (d, 12H, JH,H
ꢂ
/
3
pyl-CH3), 1.05 (s, 42H, TIPS-H), 0.91 (t, 3H, JH,H
7.69 Hz, butyl-CH3), 0.24 (s, 18H, TMS-H). 13C-NMR
(75 MHz, CDCl3): d 148.54, 142.65, 133.55, 131.93,
ꢂ
/

M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á
/39
33
CH2Cl2 and filtered through a silica gel plug. Following
removal of the solvent in vacuo and column chromato-
(C58H76FeO2Si2) 916.4733. Found 916.4728 (Eꢂ
ppm).
/3.1
graphy (SiO2Áhexanes:CH2Cl2, 1:1), 7 (32.0 mg, 71%)
/
was isolated as dark orange crystals. M.p.: 170 8C (dec.),
3.6. Synthesis of 10
black at 220 8C. IR (cmꢁ1): n 2955, 2917, 2848, 2317,
1625, 1555, 1455. H-NMR (300 MHz, CDCl3): d 7.48
1
A 50 ml round bottom flask was charged with 9 (2.02
g, 2.20 mmol), TsOH (1.50 g, 7.89 mmol) and wet THF
(10 ml). The resulting solution was stirred at ambient
temperature for 12 h before being quenched with water
and ethyl ether. The water layer was separated and
extracted with ethyl ether (250 ml). The combined
organic layers were dried over MgSO4 and the solvent
was removed in vacuo to yield a dark red oil. To the oil
in a 100 ml Schlenk flask was added K2CO3 (880 mg,
6.38 mmol), abs. THF (15 ml) and abs. methanol (15 ml)
under nitrogen. After cooling to 0 8C, dimethyl-(1-
diazo-2-oxopropyl)phosphonate (1.23 g, 6.40 mmol)
was added dropwise over 5 min. The resulting solution
is allowed to stir for 8 h before being quenched with a
saturated NaHCO3 solution (100 ml) and CH2Cl2. The
water layer was separated and extracted with CH2Cl2
(75 ml). The combined organic layers were dried over
MgSO4 and the solvent removed in vacuo. Column
(d, 2H, 3JH,H
aromatic-H), 7.22 (dd, 2H, JH,H
1.65 Hz, aromatic-H), 4.96 (s, 5H, Cp-H), 4.80 (s, 1H,
ꢂ
/
8.06 Hz, aromatic-H), 7.36Á7.34 (m, 4H,
/
3
4
8.06 Hz, JH,H
ꢂ
/
ꢂ
/
3
Cb-H), 2.87 (qt, 2H, JH,H
ꢂ
/
6.78 Hz, isopropyl-CH),
7.69 Hz, butyl-CH2), 1.64Á1.53 (m,
2H, butyl-CH2), 1.40Á1.27 (m, 2H, butyl-CH2), 1.24 (d,
6.78 Hz, isopropyl-CH3), 0.93 (t, 3H,
7.69 Hz, butyl-CH3). 13C-NMR (75 MHz,
3
2.58 (t, 2H, JH,H
ꢂ
/
/
/
3
12H, JH,H
3JH,H
ꢂ
/
ꢂ
/
CDCl3): d 148.43, 141.98, 132.57, 130.71, 130.39,
128.27, 127.57, 127.01, 123.56, 123.25 (aromatic-C),
94.77, 90.96, 90.66, 90.08, 84.55, 83.44 (alkyne-C),
82.60 (Cp-C), 79.70, 78.73 (alkyne-C), 65.62, 61.82,
59.57 (Cb-C), 35.30 (butyl-CH2), 34.02 (isopropyl-
CH), 33.02, 29.70 (butyl-CH2), 23.59 (isopropyl-CH3),
14.12 (butyl-CH3). UVÁ
/
vis (CHCl3): l 294 (oꢂ21 816
/
cmꢁ1 Mꢁ1), 324 (oꢂ24 702 cmꢁ1 Mꢁ1). MS (EI) m/z
/
Calc. for [M]ꢀ (C51H37Co) 708.2. Found 708.2.
chromatography (SiO2Áhexanes:CH2Cl2, 9:1) furnished
/
10 (1.50 g, 80%) as a red oil. IR (cmꢁ1): n 2953, 2861,
3.5. Synthesis of 9
2323, 2207, 2146, 1453, 1100. 1H-NMR (300 MHz,
3
CDCl3): d 7.47 (d, 2H, JH,H
ꢂ7.96 Hz, aromatic-H),
/
A 50 ml, oven-dried Schlenk flask was charged with 8
(1.00 g, 3.12 mmol), CuI (30.0 mg, 0.158 mmol),
Cl2Pd(PPh3)2 (44.0 mg, 0.062 mmol), 5a (2.53 g, 5.94
mmol), and abs. THF (4 ml). The flask was flushed with
nitrogen and degassed piperidine (6 ml) was added. The
resulting solution stirred at ambient temperature for 12
h before being quenched with water and ethyl ether. The
water layer was separated and extracted with ethyl ether
(100 ml). The combined organic layers were dried over
MgSO4 and the solvent removed in vacuo. Column
7.32 (d, 2H, 4JH,H
ꢂ
/
1.92 Hz, aromatic-H), 7.15 (dd, 2H,
4
7.96 Hz, JH,H 1.92 Hz, aromatic-H), 4.52 (s,
3JH,H
2H, Cp-sub. ring), 4.29 (s, 5H, Cp-unsub. ring), 3.07 (s,
ꢂ
/
ꢂ
/
1H, alkyne-H), 2.86 (qt, 2H, 3JH,H
ꢂ6.86 Hz, isopropyl-
/
3
CH), 1.22 (d, 12H, JH,H
ꢂ6.86 Hz, isopropyl-CH3),
/
1.14 (s, 42H, TIPS-H). 13C-NMR (75 MHz, CDCl3):
148.47, 133.05, 130.51, 126.66, 124.65, 123.63 (aromatic-
C), 106.04, 93.74, 88.93, 88.76, 81.86, 77.52 (alkyne-C),
74.02 (Cp-C, unsub. ring), 71.54, 70.82, 70.34 (Cp-C,
sub. ring), 33.85 (isopropyl-CH), 23.58 (isopropyl-CH3),
18.86 (TIPS-CH3), 11.38 (TIPS-CH). MS (EI) m/z Calc.
for [M]ꢀ (C56H70FeSi2) 854.4. Found 854.3.
chromatography (SiO2Á
/
hexanesꢀ10% NEt3) furnished
/
9 (2.25 g, 79%) as an orange oil. IR (cmꢁ1): n 2954,
2861, 2207, 2146, 1453, 1239, 1146, 1100. 1H-NMR (300
3
MHz, CDCl3): d 7.40 (d, 2H, JH,H
ꢂ/7.96 Hz, aro-
3.7. Synthesis of 11
4
matic-H), 7.32 (d, 2H, JH,H
ꢂ1.92 Hz, aromatic-H),
/
3
4
7.11 (dd, 2H, JH,H
matic-H), 5.68 (s, 1H, acetal-CH), 4.51 (s, 2H, Cp-sub.
ring), 4.31 (s, 5H, Cp-unsub. ring), 4.31Á4.21 (m, 2H,
acetal-CH2), 4.00Á3.92 (m, 2H, acetal-CH2), 2.85 (qt,
6.86 Hz, isopropyl-CH), 2.25Á2.15 (m, 1H,
acetal-CH2), 1.38 (m, 1H, acetal-CH2), 1.20 (d, 12H,
3JH,H
6.86 Hz, isopropyl CH3), 1.12 (s, 42H, TIPS-H).
ꢂ
/
7.96 Hz, JH,H
ꢂ
/
1.92 Hz, aro-
A 50 ml, oven-dried Schlenk flask was charged with
10 (87.0 mg, 0.102 mmol), CuI (2.2 mg, 0.012 mmol),
Pd(P(o-tol)3)2 (4.1 mg, 0.006 mmol), 4-iodo-3,5-
(triethylsilylethynyl)isopropylbenzene [2] (2b) (80.0 mg,
0.150 mmol), and abs. THF (3 ml). The flask was
flushed with nitrogen and degassed Et3N (2 ml) added.
The resulting solution stirred at ambient temperature for
12 h before being quenched with water and ethyl ether.
The water layer was separated and extracted with ethyl
ether (20 ml). The combined organic layers were dried
over MgSO4 and the solvent was removed in vacuo.
/
/
3
2H, JH,H
ꢂ
/
/
ꢂ
/
13C-NMR (75 MHz, CDCl3): 148.18, 132.10, 130.47,
126.61, 124.43, 124.14 (aromatic-C), 104.26, 99.56
(alkyne-C), 97.22 (acetal-CH), 89.74, 88.14 (alkyne-C),
86.76 (acetal-CH2), 72.86 (Cp-C, unsub. ring), 71.66,
67.45, 65.60 (Cp-C, sub. ring), 33.79 (isopropyl-CH),
25.91 (acetal-CH2), 23.56 (isopropyl-CH3), 18.86 (TIPS-
CH3), 11.38 (TIPS-CH). MS (EI) m/z Calc. for [M]ꢀ
Column chromatography (SiO2Á
furnished 11 (29 mg, 24%) as a dark redÁ
(cmꢁ1): n 2961, 2869, 2323, 2146, 1646, 1464, 1230, 992.
/hexanes:CH2Cl2, 9:1)
/orange oil. IR

34
M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á39
/
3
1H-NMR (300 MHz, CDCl3): 7.47 (d, 2H, JH,H
ꢂ
/
8.23
3.9. Synthesis of 14
Hz, aromatic-H), 7.35 (s, 2H, aromatic-H), 7.27 (d, 2H,
3
4JH,H
8.23 Hz, JH,H
Cp-sub. ring), 4.32 (s, 5H, Cp-unsub. ring), 2.84 (m, 3H,
ꢂ
/
1.37 Hz, aromatic-H), 7.04 (dd, 2H, JH,H
ꢂ
/
A 50 ml, oven-dried Schlenk flask was charged with
13 [1] (428 mg, 1.08 mmol), CuI (10.0 mg, 0.053 mmol),
Cl2Pd(PPh3)2 (15.0 mg, 0.021 mmol), 4-iodo-3-(triiso-
propylsilylethynyl)-tert-butylbenzene (5b) (1.19 g, 2.70
mmol), and abs. THF (5 ml). The flask was flushed with
nitrogen and degassed piperidine (6 ml) was added. The
resulting solution was stirred at ambient temperature for
12 h before being quenched with water and ethyl ether.
The water layer was separated and extracted with ethyl
ether (50 ml). The combined organic layers were dried
over MgSO4 and the solvent removed in vacuo. Column
4
ꢂ1.37 Hz, aromatic-H), 4.54 (s, 2H,
/
3
isopropyl-CH), 1.26 (d, 12H, JH,H
pyl-CH3), 1.22 (d, 6H, 3JH,H
ꢂ
/
6.86 Hz, isopro-
ꢂ
/
6.86 Hz, isopropyl-CH3),
1.18 (s, 42H, TIPS-H), 0.96 (m, 18H, TES-CH3), 0.85
(m, 12H, TES-CH2). 13C-NMR (75 MHz, CDCl3):
148.04, 147.96, 133.64, 131.43, 131.22, 130.50, 126.35,
125.53, 124.32, 124.13 (aromatic-C), 106.23, 104.86,
96.16, 93.31, 92.99, 89.75, 88.42, 88.05 (alkyne-C),
74.07 (Cp-C, unsub. ring), 72.50, 71.09, 69.54 (Cp-C,
sub. ring), 33.91, 33.78 (isopropyl-CH), 23.64, 23.58
(isopropyl-CH3), 18.87 (TIPS-CH3), 11.40 (TIPS-CH),
7.53 (TES-CH3), 4.30 (TES-CH2). MS (EI) m/z Calc.
for [M]ꢀ (C81H108FeSi4) 1248.7. Found 1248.8.
chromatography (SiO2Á
/
hexanesꢀ10% NEt3) furnished
/
14 (650 mg, 59%) as an orange oil. IR (cmꢁ1): n 2954,
2864, 2149, 1464, 1237, 1106, 1005. 1H-NMR (300
4
MHz, CDCl3): d 7.41 (d, 2H, JH,H
ꢂ1.92 Hz, aro-
/
3
matic-H), 7.37 (d, 2H, JH,H
ꢂ8.23 Hz, aromatic-H),
/
3
4
7.22 (dd, 2H, JH,H
matic-H), 5.20 (s, 2H, acetal-CH), 4.99 (s, 5H, Cp-H),
4.16Á4.12 (m, 4H, acetal-CH2), 3.83Á3.78 (m, 4H,
acetal-CH2), 2.05Á1.97 (m, 2H, acetal-CH2), 1.38Á1.34
ꢂ
/
8.23 Hz, JH,H
ꢂ/1.92 Hz, aro-
3.8. Synthesis of 12
/
/
/
/
A 50 ml, round bottom flask was charged with 11 (125
mg, 0.100 mmol), Bu4NꢀFꢁ (0.500 ml, 1.0 M in THF)
and THF (2 ml). The resulting solution was stirred at
ambient temperature for 1 h before being quenched with
water and ethyl ether. The water layer was separated
and extracted with ethyl ether (50 ml). The combined
organic layers were dried over MgSO4 and the solvent
removed in vacuo to yield a dark red oil. To the oil, in a
250 ml round bottom flask, was added Cu(OAc)2 (400
mg, 2.21 mmol) and MeCN (100 ml). The resulting
solution was heated to 80 8C for 6 h. The solvent was
removed in vacuo, the resulting mixture was dissolved in
CH2Cl2 and filtered through a silica gel plug. Following
removal of the solvent in vacuo and column chromato-
(m, 2H, acetal-CH2), 1.27 (s, 18H, t-butyl-CH3), 1.08 (s,
42H, TIPS-H). 13C-NMR (75 MHz, CDCl3): d 150.17,
132.64, 129.60, 125.06, 124.11, 123.97 (aromatic-C),
106.21 (alkyne-C), 97.89 (acetal-CH), 93.56, 91.23,
88.24 (alkyne-C), 82.29 (Cp-C), 76.86 (Cb-C), 66.45
(acetal-CH2), 56.19 (Cb-C), 34.39 (t-butyl-C), 30.84 (t-
butyl-CH3), 25.83 (acetal-CH2), 18.67 (TIPS-CH3),
11.20 (TIPS-CH). MS (EI) m/z Calc. for [M]ꢀ
(C63H85CoO4Si2) 1020.5318. Found 1020.5346.
3.10. Synthesis of 15
A 50 ml round bottom flask was charged with 14 (650
mg, 0.640 mmol), TsOH (240 mg, 1.26 mmol) and THF
(10 ml). The resulting solution was stirred at ambient
temperature for 12 h before being quenched with water
and ethyl ether. The water layer was separated and
extracted with ethyl ether (100 ml). The combined
organic layers were dried over MgSO4 and the solvent
removed in vacuo to yield a dark red oil. To the oil, in a
100 ml Schlenk flask, was added K2CO3 (560 mg, 4.06
mmol), abs. THF (10 ml) and abs. methanol (10 ml)
under nitrogen. After cooling to 0 8C, dimethyl-(1-
diazo-2-oxopropyl)phosphonate [4] (560 mg, 2.92
mmol) was added dropwise over 5 min. The resulting
solution was allowed to stir for 18 h before being
quenched with a saturated NaHCO3 solution (50 ml)
and CH2Cl2. The water layer was separated and
extracted with CH2Cl2 (100 ml). The combined organic
layers were dried over MgSO4 and the solvent was
graphy (SiO2Áhexanes:CH2Cl2, 1:1), 12 (44.0 mg, 63%)
/
is isolated as dark redÁorange needles. M.p.: 220 8C
/
(turned dark). IR (cmꢁ1): n 2954, 2923, 2869, 2323,
2196, 1730, 1538, 1453, 1061. 1H-NMR (300 MHz,
CDCl3): 7.61 (d, 2H, 3JH,H
(s, 2H, aromatic-H), 7.32 (d, 2H, JH,H
ꢂ7.96 Hz, aromatic-H), 7.47
/
4
ꢂ1.37 Hz,
/
3
4
aromatic-H), 7.26 (dd, 2H, JH,H
1.37 Hz, aromatic-H), 4.96 (s, 2H, Cp-sub. ring), 4.26
(s, 5H, Cp-unsub. ring), 2.96Á2.87 (m, 3H, isopropyl-
CH), 1.29Á
1.21 (m, 18H, isopropyl-CH3). 13C-NMR (75
ꢂ/8.23 Hz, JH,H
ꢂ
/
/
/
MHz, CDCl3): 148.43, 147.77, 132.12, 130.45, 129.51,
128.79, 127.37, 126.56, 123.91, 122.44 (aromatic-C),
94.23, 92.11, 89.42, 87.31, 86.02, 84.96, 81.49, 78.14
(alkyne-C), 77.10 (Cp-C, sub. ring), 73.95 (Cp-C, unsub.
ring), 73.89, 70.21 (Cp-C, sub. ring), 33.98, 33.74
(isopropyl-CH), 23.66, 23.51 (isopropyl-CH3). UVÁ
(CHCl3): l 312 (oꢂ
62 094 cmꢁ1 Mꢁ1). MS (EI) m/z
Calc. for [M]ꢀ (C51H36Fe) 704.2166. Found 704.2149
(Eꢂ2.4 ppm).
/
vis
removed in vacuo. Column chromatography (SiO2Á
/
/
hexanesꢀ10% NEt3) furnished 15 (450 mg, 80%) as a
/
dark orange oil. IR (cmꢁ1): n 2957, 2858, 2153, 1462,
1
1385, 1258, 990. H-NMR (300 MHz, CDCl3): d 7.43
/

M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á
/39
35
4
(d, 2H, JH,H
3JH,H
8.23 Hz, aromatic-H), 7.25 (dd, 2H, JH,H
8.23 Hz, JH,Hꢂ1.92 Hz, aromatic-H), 5.00 (s, 5H,
ꢂ
/
1.92 Hz, aromatic-H), 7.40 (d, 2H,
Cu(OAc)2 (310 mg, 1.71 mmol) and MeCN (200 ml).
The resulting solution was heated to 80 8C for 6 h. The
solvent was removed in vacuo, the resulting mixture
redissolved in CH2Cl2 and filtered through a silica gel
plug. Following removal of the solvent in vacuo and
3
ꢂ
/
ꢂ
/
4
/
Cp-H), 3.25 (s, 2H, alkyne-H), 1.29 (s, 18H, t-butyl-
CH3), 1.09 (s, 42H, TIPS-H). 13C-NMR (75 MHz,
CDCl3): d 151.13, 132.44, 129.63, 125.27, 124.82,
123.05 (aromatic-C), 105.75, 94.39, 92.60, 86.25, (al-
kyne-C), 83.80 (Cp-C), 81.72, 77.69 (alkyne-C), 61.31,
59.82 (Cb-C), 34.59 (t-butyl-C), 30.91 (t-butyl-CH3),
18.79 (TIPS-CH3), 11.24 (TIPS-CH). MS (EI) m/z Calc.
for [M]ꢀ (C59H73CoSi2) 896.4583. Found 896.4577
column chromatography (SiO2Áhexanes:CH2Cl2, 1:1),
/
17 (18 mg, 25%) was isolated as dark orange crystals.
M.p.: 136 8C (turned dark), black at 230 8C. IR (cmꢁ1):
n 2952, 2920, 2852, 2177, 1731, 1458, 1260, 1099, 1018.
3
1H-NMR (300 MHz, CDCl3): d 7.67 (d, 2H, JH,H
ꢂ
/
4
8.23 Hz, aromatic-H), 7.55 (d, 2H, JH,H
ꢂ1.92 Hz,
/
3
4
(Eꢂ
/
2.6 ppm).
aromatic-H), 7.45 (dd, 2H, JH,H
1.92 Hz, aromatic-H), 7.36 (s, 4H, aromatic-H), 4.93
(s, 5H, Cp-H), 2.61 (t, 4H, 3JH,H
7.69 Hz, butyl-CH2),
1.66Á1.56 (m, 4H, butyl-CH2), 1.34 (s, 18H, t-butyl-
CH3), 1.39Á1.24 (m, 4H, butyl-CH2), 0.93 (t, 6H,
3JH,H 7.69 Hz, butyl-CH3). 13C-NMR (75 MHz,
ꢂ
/
8.23 Hz, JH,H
ꢂ
/
3.11. Synthesis of 16
ꢂ
/
/
A 50 ml, oven-dried Schlenk flask was charged with
15 (450 mg, 0.500 mmol), CuI (11.0 mg, 0.059 mmol),
Pd(P(o-tol)3)2 (21.0 mg, 0.030 mmol), 2a [2] (700 mg,
1.27 mmol), and abs. THF (7 ml). The flask was flushed
with nitrogen and degassed Et3N (5 ml) was added. The
resulting solution was stirred at ambient temperature for
12 h before being quenched with water and ethyl ether.
The water layer was separated and extracted with ethyl
ether (100 ml). The combined organic layers were dried
over MgSO4 and the solvent was removed in vacuo.
/
ꢂ
/
CDCl3): d 151.00, 142.26, 132.26, 130.91, 130.60,
130.49, 127.30, 126.64, 126.47, 123.80, 123.50, 123.10
(aromatic-C), 94.05, 92.64, 91.52, 89.04, 84.78, 83.91
(alkyne-C), 83.78 (Cp-C), 83.27, 79.73, 79.51, 78.73
(alkyne-C), 63.02, 62.08 (Cb-C), 35.31(butyl-CH2),
34.96 (t-butyl-C), 33.01 (butyl-CH2), 31.03 (t-butyl-
CH3), 22.21 (butyl-CH2), 13.90 (butyl-CH3). UVÁ
/
vis
(CHCl3): l 302 (oꢂ
/
10 577 cmꢁ1 Mꢁ1), 340 (oꢂ
/
9248
Column chromatography (SiO2Á
/
hexanes:CH2Cl2, 4:1)
cmꢁ1 Mꢁ1). MS (EI) m/z unable to determine because
decomposition occurred before [M]ꢀ could be deter-
mined.
furnished 16 (134 mg, 16%) as a dark orange oil. IR
(cmꢁ1): n 2953, 2864, 2157, 1462, 1239, 1005. 1H-NMR
(300 MHz, CDCl3): d 7.40 (m, 4H, aromatic-H), 7.21
(m, 6H, aromatic-H), 5.02 (s, 5H, Cp-H), 2.50 (t, 4H,
3.13. Synthesis of 20
3JH,H
CH2), 1.28 (s, 18H, t-butyl-CH3), 1.09Á
TIPS-H, TES-CH3, butyl-CH2), 0.72Á0.50 (m, 24H,
ꢂ
/
7.69 Hz, butyl-CH2), 1.60Á
/1.49 (m, 4H, butyl-
/
0.82 (m, 86H,
In a 100 ml, oven-dried Schlenk flask 8 (1.12 g, 3.50
mmol) was dissolved in dry THF (50 ml). Butyllithium
(3.85 ml, 2.0 M, 7.70 mmol) was added dropwise at
/
TES-CH2, butyl-CH3). 13C-NMR (75 MHz, CDCl3): d
150.59, 141.87, 133.11, 133.02, 132.75, 129.62, 128.66,
126.13, 126.09 (aromatic-C), 125.36 (alkyne-C), 125.10,
124.80, 123.74 (aromatic-C), 105.81, 104.51, 96.07,
94.23, 92.52, 91.36, 90.76, 87.31 (alkyne-C), 84.40 (Cp-
C), 84.10 (alkyne-C), 62.66, 61.70 (Cb-C), 35.07 (butyl-
CH2), 34.63 (t-butyl-C), 33.13 (butyl-CH2), 30.99 (t-
butyl-CH3), 22.25 (butyl-CH2), 18.69 (TIPS-CH3), 13.89
(butyl-CH3), 11.31 (TIPS-CH), 7.52 (TES-CH2), 4.34
(TES-CH3). MS (EI) m/z Calc. for [M]ꢀ
(C111H153CoSi6) 1713.0. Found 1712.9.
ꢁ78 8C. After stirring for 30 min, the mixture was
/
allowed to warm to 0 8C and CuI (3.00 g, 15.8 mmol)
was added. Following 15 min of stirring, the mixture
was brought to ꢁ20 8C, where propylamine (40 ml) and
/
19 (3.40 g, 8.45 mmol) were added successively and
stirring continued at ambient temperature for 1 h. The
reaction was quenched with water and extracted with
ethyl ether. The organic layers were collected, dried over
MgSO4 and the solvent was removed in vacuo. Column
chromatography (SiO2; hexanesÁCH2Cl2, 9:1) furnished
/
20 (1.55 g, 46%) as a red oil. IR (neat): n (cmꢁ1) 2941,
1
2890, 2213, 2150, 1463, 1454, 1097, 996. H-NMR (300
3.12. Synthesis of 17
MHz, CDCl3): d 7.18 (d, 2H, 3JH,H
ꢂ8.0 Hz, aromatic-
/
4
A 50 ml, round bottom flask was charged with 16 (134
mg, 0.080 mmol), Bu4NF (0.550 ml, 1.0 M in THF) and
THF (5 ml). The resulting solution was stirred at
ambient temperature for 1 h before being quenched
with water and ethyl ether. The water layer was
separated and extracted with ethyl ether (50 ml). The
combined organic layers were dried over MgSO4 and the
solvent was removed in vacuo to yield a dark red oil. To
the oil, in a 500 ml round bottom flask, was added
H), 7.06 (d, 2H, JH,H
ꢂ
/
1.6 Hz, aromatic-H), 6.86 (dd,
1.6 Hz, aromatic-H), 5.31
(s, 1H, acetal-CH), 4.29 (s, 2H, sub. Cp-H), 4.10 (s, 5H,
Cp-H), 4.09Á3.98 (m, 2H, acetal-CH2), 3.78Á3.66 (m,
2H, acetal-CH2), 2.62 (sept, 2H, 3JH,H
6.9 Hz, isopro-
pyl-CH), 2.05Á1.98 (m, 1H, acetal-CH2), 1.18Á
3
4
2H, JH,H
ꢂ/8.0 Hz, JH,H
ꢂ
/
/
/
ꢂ
/
/
/1.13 (m,
3
2H, acetal-CH2), 0.98 (d, 12H, JH,H
ꢂ/6.9 Hz, isopro-
pyl-CH), 0.93 (s, 42H, TIPS-H). 13C-NMR (75 MHz,
CDCl3): d 149.59, 132.78, 130.38, 126.74, 126.46,

36
M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á39
/
122.60, 105.18, 98.87, 94.95, 89.83, 79.80, 78.29, 77.96,
73.08, 73.01, 67.59, 64.29, 33.98, 23.53, 18.76, 11.31. MS
(EI) m/z Calc. for [M]ꢀ (C62H76FeO2Si2) 964.4733.
(810 mg, 1.38 mmol) were added successively. Stirring
continued at ambient temperature for 1 h. The reaction
was quenched with water and extracted with ethyl ether.
The organic layer was collected, dried over MgSO4 and
the solvent removed in vacuo. Column chromatography
Found 964.47.4 (Eꢂ
/
3.0 ppm).
3.14. Synthesis of 21
(SiO2; hexanesÁCH2Cl2, 4:1) furnished 23 (140 mg,
/
24%) as a red oil. IR (neat): n (cmꢁ1) 2957, 2891,
1
2220, 2154, 1464, 1250, 1071, 999. H-NMR (300 MHz,
Ketal 20 (1.06 g, 1.10 mmol), TsOH (314 mg, 1.65
mmol), THF (2 ml) and H2O (3 ml) were placed in a 100
ml round bottom flask. The resulting mixture was
stirred for 1 h under the exclusion of light. The mixture
was quenched with water and extracted with ethyl ether
(100 ml). Removal of the solvent in vacuo and drying in
a 100 ml Schlenk flask under vacuum (10ꢁ1 mbar)
yielded a red oil. To a 100 ml oven-dried Schlenk flask
was added (trimethylsilyl)diazomethane (2.8 ml, 2.0 M
solution in THF) and dry THF (20 ml). After cooling
3
CDCl3): 7.39 (d, 2H, JH,H
ꢂ5.8 Hz, aromatic-H), 7.28
/
4
(d, 2H, JH,H
aromatic-H), 7.09 (dd, 2H, JH,H
Hz, aromatic-H), 4.64 (s, 2H, Cp-H sub. ring), 4.39 (s,
ꢂ/1.6 Hz, aromatic-H), 7.19 (s, 2H,
3
4
ꢂ
/
5.8 Hz, JH,H
ꢂ1.6
/
3
2H, Cp-H unsub. ring), 2.84 (sept, 2H, JH,H
ꢂ
/
6.9 Hz,
8.0 Hz, butyl CH2),
1.54 (m, 2H, butyl-CH2), 1.27Á1.19 (m, 4H,
isopropyl-CH, butyl-CH2), 1.15 (s, 42H, TIPS-H), 0.98
0.81 (m, 16H, butyl-CH3, t-
3
isopropyl-CH), 2.51 (t, 2H, JH,H
1.70Á
ꢂ
/
/
/
(s, 12H, t-hexyl-CH3), 0.96Á
/
the solution to ꢁ
/
78 8C, butyllithium (1.4 ml, 1.65 mmol)
hexyl-CH, CH3), 0.25 (s, 12H, t-hexyl-CH3). 13C-NMR
(75 MHz, CDCl3): d 149.70, 143.22, 132.64, 131.68,
130.36, 127.31, 127.08, 126.36, 125.26, 122.47, 105.02,
130.46, 99.32, 95.19, 81.79, 79.24, 78.88, 78.28, 77.85,
76.43, 74.20, 73.34, 68.83, 34.69, 32.97, 29.70, 23.55,
23.48, 22.65, 22.28, 20.90, 18.78, 13.88, 11.34.
was added dropwise. After stirring for 5 min the
reaction was warmed to 0 8C and the solution homo-
genized. The mixture was recooled to ꢁ50 8C. To the
flask containing the ferrocene starting material was
added dry THF (50 ml) under nitrogen. This solution
/
was added slowly to the solution at ꢁ
keep the temperature below ꢁ40 8C. After the addition,
40 8C
/
50 8C so as to
/
3.16. Synthesis of 24
the reaction mixture was stirred for 15 min at ꢁ
/
after which time NH4ꢀClꢁ (aqueous, 50 ml) was added.
The reaction was brought to ambient temperature. The
reaction mixture was extracted twice with ethyl ether
and the combined organic layers were dried over
MgSO4. The solvent was removed in vacuo. Column
A 50 ml, round bottom flask was charged with 25 (140
mg, 0.100 mmol), Bu4NꢀFꢁ (0.50 ml, 1.0 M in THF),
and THF (3 ml). The resulting solution was stirred at
ambient temperature for 1 h before being quenched with
water and ethyl ether. The water layer was separated
and extracted with ethyl ether (50 ml). The combined
organic layers were dried over MgSO4 and the solvent
removed in vacuo to yield a dark red oil. The oil was
placed in a 100 ml round bottom flask and reacted with
Cu(OAc)2 (400 mg, 2.20 mmol) in CH3CN (250 ml) at
chromatography (SiO2; CH2Cl2Áhexanes, 4:1) furnished
/
21 (379 mg, 58%) as a red oil. IR (neat): n (cmꢁ1) 2959,
1
2864, 2216, 1491, 1464, 1070, 995. H-NMR (300 MHz,
3
CDCl3): 7.41 (d, 2H, JH,H
ꢂ5.8 Hz, aromatic-H), 7.31
/
4
(d, 2H, JH,H
3JH,H
5.8 Hz, JH,H
2H, Cp-H sub. ring), 4.35 (s, 2H, Cp-H unsub. ring),
ꢂ
/
1.6 Hz, aromatic-H), 7.12 (dd, 2H,
4
ꢂ
/
ꢂ
/
1.6 Hz, aromatic-H), 4.60 (s,
80 8C for 8 h. Column chromatography (SiO2; hexanesÁ
EtOAc, 4:1) furnished 24 (14 mg, 18%) as an orange
/
3
3.01 (s, 1H, alkyne-H), 2.86 (sept, 2H, JH,H
3
isopropyl-CH), 1.21 (d, 12H, JH,H
ꢂ
/
6.9 Hz,
crystalline solid. M.p. ꢀ100 8C (dec.). IR (neat): n
/
ꢂ/6.9 Hz, isopropyl-
(cmꢁ1) 2940, 2869, 2841, 2223, 2150, 1538, 1453, 1001.
CH), 1.18 (s, 42H, TIPS-H). 13C-NMR (75 MHz,
CDCl3): d 149.84, 132.73, 130.39, 126.97, 126.50,
122.37, 105.05, 79.68, 79.07, 79.93, 77.49, 74.29, 73.71,
72.86, 70.09, 71.11, 68.23, 34.02, 23.55, 18.80, 11.34. MS
(EI) m/z Calc. for [M]ꢀ (C60H70FeSi2) 902.4365. Found
1H-NMR (300 MHz, CD2Cl2): 7.50 (s, 2H, aromatic-H),
3
7.48 (d, 2H, JH,H
ꢂ5.8 Hz, aromatic-H), 7.42 (s, 2H,
/
3
aromatic-H), 7.22 (dd, 2H, JH,H
4
5.8 Hz, JH,H
Hz, aromatic-H), 4.65 (s, 2H, Cp-H sub. ring), 4.42 (s,
ꢂ
/
ꢂ1.6
/
3
2H, Cp-H unsub. ring), 2.91 (sept, 2H, JH,H
ꢂ
/
6.9 Hz,
8.0 Hz, butyl CH2),
1.56 (m, 2H, butyl-CH2), 1.40Á1.31 (m, 2H, butyl-
CH2), 1.25 (s, 12H, 3JH,H
6.9 Hz, isopropyl-CH3), 0.86
(t, 3H, 3JH,H 8.0 Hz, butyl-CH3). 13C-NMR (75 MHz,
3
902.4313 (Eꢂ
/
5.8 ppm).
isopropyl-CH), 2.62 (t, 2H, JH,H
ꢂ
/
1.64Á
/
/
3.15. Synthesis of 23
ꢂ
/
ꢂ
/
In a 250 ml, oven-dried Schlenk flask 21 (379 mg,
0.420 mmol) was dissolved in dry THF (50 ml).
Butyllithium (0.4 ml, 0.924 mmol) was added dropwise
CD2Cl2): d 150.74, 144.53, 133.26, 133.21, 132.37,
128.43, 127.24, 125.56, 124.89, 122.50, 82.73, 81.98,
81.63, 80.47, 80.29, 79.25, 78.26, 77.93, 77.78, 77.13,
76.70, 75.32, 75.12, 74.64, 71.57, 69.07, 35.62, 34.41,
33.32, 23.61, 22.54, 13.99. MS (EI) m/z Calc. for [M]ꢀ
(C58H38Fe) 790.2323, decomposition before [M]ꢀ could
be determined.
at ꢁ78 8C. After stirring for 30 min, the mixture was
/
allowed to warm to 0 8C and CuI (120 mg, 0.632 mmol)
was added. Following 15 min of stirring the mixture was
brought to ꢁ20 8C, where propylamine (15.0 ml) and 22
/

M. Laskoski et al. / Journal of Organometallic Chemistry 673 (2003) 25Á
/39
37
˚
˚
˚
3.17. Details of X-ray crystal structure determination
10.568(1) A, bꢂ
102.215(3)8, and Vꢂ
independent molecules in the unit cell, Dcalc
cmꢁ3. Intensity data covering the full sphere of
reciprocal space were measured to 2umax 45.18;
21 290 reflections were collected of which 7278 were
independent and of those were 3104 with I ꢀ2s(I). No
absorption correction was applied (mꢂ
0.35 mmꢁ1).
Data refinement produced R1ꢂ0.2544, wR2(I ꢀ
2s(I)ꢂ0.1098, with a GoFꢂ1.008. 605 parameters
were refined. Molecular disorder corresponding to a 908
rotation around the CoꢀCpcentroid vector is present, but
could not be modeled due to the small fraction (B10%).
/
35.490(4) A, cꢂ
/
15.132(2) A, bꢂ
/
3
˚
/
5547.0(11) A . There are Zꢂ
/
4
X-ray intensity data for 7, 12 and 17 were measured in
v-scan mode using a Bruker SMART APEX CCD-
ꢂ
/
1.124 g
based diffractometer system with MoÁ
/
Ka radiation at
0.71073 A, at 190(2) K. Raw data frame integration
and Lorentz and polarization corrections were per-
formed with SAINTꢀ. Structure solution (direct methods
in all cases) and refinement against F2 using all data was
performed with SHELXTL
ꢂ
/
˚
lꢂ
/
/
/
/
/
/
.
/
/
3.17.1. Crystal data for 7
The cyclobutadiene complex C51H37Co of the FWꢂ
708.74 was isolated as orange rhombus, (0.36ꢃ0.20ꢃ
0.06 mm). The unit cell was triclinic featuring the space
/
/
/
/
/
One butyl substituent is severely disordered; coordinates
and isotropic thermal parameters were fixed once a
reasonable geometry was attained. A region of diffuse
solvent was located near the disordered butyl group and
˚
¯
group P
12.1458(8) A, cꢂ
79.657(1)8, gꢂ65.458(1)8, Vꢂ
molecules in the unit cell. The calculated density,
Dcalc
1.281 g cmꢁ3. Intensity data covering the full
sphere of reciprocal space were measured to 2umax
/
1; with cell dimensions of aꢂ
/
10.9507(8) A, bꢂ
15.4401(11) A, aꢂ86.981(1)8, bꢂ
1837.2(2) A , and Zꢂ
/
˚
˚
/
/
/
3
˚
/
/
/
2
treated with SQUEEZE (solvent-accessible volumeꢂ
/
588.1 A , 169 e cellꢁ1, corresponding to three CHCl3
3
˚
ꢂ
/
molecules per C69H59Co molecule). Max/min residual
electron density was determined to ꢀ
ꢂ
/
/
1.475/ꢁ1.075 e
/
ꢁ3
˚
A
50.28; 15 359 reflections were collected, of which 6532
were independent, of which 5052 were recorded with
.
I ꢀ
0.50 mmꢁ1). Data refinement produced R1ꢂ
wR2(I ꢀ2s(I)ꢂ0.0416; GoFꢂ1.015. 495 parameters
were refined, with no restraints. Max/min residual
electron density was determined to ꢀ0.327/ꢁ0.244 e
/
2s(I). No absorption correction was applied (mꢂ
/
/0.0814,
4. Supplementary material
/
/
/
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 176513 for compound 7,
CCDC No. 176514, for compound 12, and CCDC No.
176515 for compound 17. Copies of this information
may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
/
/
ꢁ3
˚
A
.
3.17.2. Crystal data for 12
The ferrocene derivative C51H36Fe×
the FWꢂ725.88 was isolated as orange needle of the
dimensions of 0.42ꢃ0.12ꢃ0.08 mm. The material
crystallized in the hexagonal crystal system in the space
/0.25(CH2Cl2) of
/
/
/
(Fax:
ac.uk or www: http://www.ccdc.cam.ac.uk).
ꢀ44-1223-336033; e-mail: deposit@ccdc.cam.
/
˚
group P63 with unit cell dimensions of aꢂ
/
27.174(2) A,
5830.4(7) A , and Zꢂ 6 indepen-
dent molecules. The calculated density was determined
to Dcalc
1.240 g cmꢁ3. Intensity data covering the full
sphere of reciprocal space were measured to 2umax
3
˚
˚
cꢂ
/
9.1170(7) A, Vꢂ
/
/
Acknowledgements
ꢂ
/
ꢂ
/
The authors thank the National Science Foundation
for generous support (Bunz, CAREER, CHE 99-81765).
U.H.F.B. is Camille Dreyfus Teacher-Scholar (2000Á
48.28; 22 326 reflections were collected of which 5788
were independent; 4316 reflections were recorded with
/
I ꢀ
0.46 mmꢁ1). Data refinement produced R1ꢂ
wR2(I ꢀ2s(I)ꢂ0.0623, with a of GoFꢂ1.013; 509
/
2s(I). No absorption correction was applied (mꢂ
/
2004).
/0.1231,
/
/
/
parameters were refined with four restraints due to
disordered CH2Cl2 solvent. Max/min residual electron
References
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parameterꢂ
PLATON) was negative.
/
0.355/ꢁ
/
0.385 e Aꢁ3. Flack
˚
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(c) S. Grimme, J. Am. Chem. Soc. 118 (1996) 1529;
(d) D. Kuck, Chem. Ber. 127 (1994) 409.
[22] An example of a hexagonal fenestrane geometry see: W.B. Wan,
M.M. Haley, J. Org. Chem. 66 (2001) 3893.
[23] For examples of planar carbon and bona fide fenestrane
geometries in organic and organometallic chemistry see: (a) D.