Appreciably bent sp carbon chains: Synthesis, structure, and protonation of organometallic 1,3,5-triynes and 1,3,5,7-tetraynes of the formula (η5-C5Me5)Re(NO)(PPh 3)((C≡C)n-p-C6H4</sub

Article abstract of DOI:10.1016/S0022-328X(98)01128-0

The diyne (η⁵-C₅Me₅)Re(NO)(PPh ₃)(C≡CC=CSiMe₃) is elaborated to (η⁵-C₅Me₅)Re(NO)(PPh ₃)(C≡CC≡CC≡CSiR₃) (R = Me, 3a; Et, 3b) by sequences involvin

Full text of DOI:10.1016/S0022-328X(98)01128-0

Journal of Organometallic Chemistry 578 (1999) 229–246
Appreciably bent sp carbon chains: synthesis, structure, and
protonation of organometallic 1,3,5-triynes and 1,3,5,7-tetraynes of the
formula (h5-C5Me5)Re(NO)(PPh3)((CꢀC)n-p-C6H4Me)
Roman Dembinski a, Tadeusz Lis b, Slawomir Szafert a, Charles L. Mayne a, Tama´s Bartik a,
J.A. Gladysz a,c,
*
a Department of Chemistry, Uni6ersity of Utah, Salt Lake City, UT 84112, USA
b
*
*
Department of Chemistry, Uni6ersity of Wroclaw, 14 F. Joliot-Curie, 50-383 Wroclaw, Poland
c Institut fu¨r Organische Chemie, Friedrich–Alexander Uni6ersita¨t Erlangen–Nu¨rnberg, Henkestrasse 42, 91054 Erlangen, Germany
Received 25 August 1998
Abstract
The diyne (h5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCSiMe3) is elaborated to (h5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀCSiR3) (R=Me,
3a; Et, 3b) by sequences involving n-Bu4N+F− in aqueous THF to give (h5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCH) (91%), n-BuLi/
CuI or t-BuOCu to give (h5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCu) (4), and coupling with ICꢀCSiMe3 (48%) or BrCꢀCSiEt3
(84–65%). Complex 3b is similarly converted to (h5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀCH) (88%) and (h5-
C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀCCu) (6). Reactions of 4 and 6 with BrCꢀC-p-C6H4Me give the title compounds (h5-
C5Me5)Re(NO)(PPh3)((CꢀC)n-p-C6H4Me) (n=3, 7; 4, 8; 77–66%). Optimized one flask conversions of 1a and 3b to 7 (81%) and
˚
8 (71%) are described. The crystal structures of 7 (monoclinic, P21/c, a/b/c=17.951(8)/8.377(5)/22.160(9) A, i=103.63(5)°,
˚
Z=4), and 8 (monoclinic, P21/n, a/b/c=8.426(3)/16.400(6)/25.400(9) A, i=97.51(3)°, Z=4) show markedly curved sp carbon
chains—much more than hexatriynes or octatetraynes reported to date. The bond angles associated with the Re(CꢀC)nC moieties
(min/max/avg) are 169.1(10)°/178.8(13)°/174.7° (7) and 170.0(9)°/178.8(10)°/175.7° (8). Other structural features are normal, and
bending is provisionally ascribed to packing forces. Reaction of 7 and HBF4·OEt2 gives the cationic vinylidene complex
[(h5-C5Me5)Re(NO)(PPh3)(CꢁC(H)CꢀCCꢀC-p-C6H4Me)]+BF4−, the structure of which is established by extensive NMR analyses.
© 1999 Elsevier Science S.A. All rights reserved.
Keywords: Rhenium; Polyynes; Crystallography; Bent carbon chains
1. Introduction
graphite (sp2 lattice). It should have a linear ground
state, but remains difficult to generate, isolate, and
characterize. In this context, there has been conjecture
that long sp carbon chains might have low energy
barriers to bending, and readily convert to various
fullerenes [4,5].
We have sought to probe this point with model
compounds. In 1997, we surveyed all crystallographi-
cally characterized compounds with at least eight con-
secutive sp hybridized carbons [6]. These included six
1,3,5,7-tetraynes [4b,6,7,8,9,10] and a 1,3,5,7,9-pentayne
[11], but no cumulenes. However, none exhibited appre-
The previous decade has seen many stunning new
breakthroughs in the field of carbon allotropes [1,2].
The importance of this area, as well as specific achieve-
ments, were recognized in the 1996 Nobel Prizes in
chemistry [2]. One ongoing topic of controversy con-
cerns the polymeric sp carbon allotrope, often termed
‘carbyne’ [3]. This substance ranks in conceptual impor-
tance as a full equal of diamond (sp3 lattice) and
* Corresponding author.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01128-0

230
R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
ciable chain bending. In the meantime, we have contin-
ued to structurally characterize all such crystalline com-
pounds synthesized in our laboratory. Many of these
serve as intermediates in the preparation of complexes
in which sp carbon chains span two transition metals,
pling with a haloalkyne to give a 1,3-diyne moiety [14].
We have made extensive use of such protocols to
extend sp carbon chains in metal co-ordination spheres
[6,12b,c]. In connection with several objectives, we
sought chains with organorhenium and p-tolyl end-
groups. Thus, the known bromoalkyne BrCꢀC-p-
C6H4Me [15] was prepared in 72% yield by a new route
from the corresponding terminal alkyne, NBS, and
AgNO3, as described in the experimental section [16].
This compound can be kept for months at −10°C with
only slight decomposition.
[LnMCxM%L% ]. This separate area of endeavor is cur-
n%
rently receiving intense attention in many research
groups [12,13].
In this paper, we report the synthesis and crystal
structure of the first 1,3,5,7-tetrayne that shows appre-
ciable sp carbon chain bending, as well as a 1,3,5-triyne
homolog that is even more deformed. These com-
pounds feature a p-C6H4Me (p-tolyl) group on one
terminus, and the chiral rhenium fragment (h5-
C5Me5)Re(NO)(PPh3) (I) on the other. The molecular
structures and packing motifs are carefully analyzed
and compared. The protonation of the triyne ligand is
also studied. Attack occurs upon the carbon beta to
rhenium to give a cationic vinylidene complex.
The required Re(CꢀC)nCu coupling partners have
been described in brief notes or communications
[6,12b]. This study was used as an opportunity to fully
optimize the synthetic sequence, and provide full details
for each step. A key building block, the trimethylsilyl
capped butadiynyl complex (h5-C5Me5)Re(NO)-
(PPh3)(CꢀCCꢀCSiMe3) (1a), was synthesized by depro-
tonation of a cationic p alkyne complex as described in
a full paper [17]. As shown in Scheme 1, 1a could be
converted
to
the
butadiynyl
complex
(h5-
2. Results
C5Me5)Re(NO)(PPh3)(CꢀCCꢀCH) (2) in two ways: (1)
K2CO3 in methanol, a previously reported recipe that
requires 8–12 h for completion [18], or (2) n-
Bu4N+F− (0.2 equivalents; 5% water by weight) in
THF, a new protocol that requires only 0.5 h. Workups
gave 2 in 91–84% yields.
2.1. Syntheses of polyalkynyl compounds
The ‘Cadiot–Chodkiewicz’ reaction entails the gener-
ation of an alkynyl copper species, followed by cou-
Scheme 1. Syntheses of 1,3,5-hexatriynyl complexes 3a and 3b.

R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
231
The trimethylsilyl capped hexatriynyl complex (h5-
C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀCSiMe3) (3a) and tri-
ethylsilyl analog (h5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀ
CSiEt3) (3b) were synthesized as summarized in Scheme
1. The former has not been reported earlier. First, 2
was deprotonated with n-BuLi (1.05 equivalents,
−45°C) in the presence of CuI in THF to generate a
species of empirical formula (h5-C5Me5)Re(NO)
(PPh3)(CꢀCCꢀCCu) (4) [6,12b,c,19]. Then an excess of
EtNH2 was added (−20°C), followed by the dropwise
delivery of ICꢀCSiMe3 [20] or BrCꢀCSiEt3 [21].
These known haloalkynes were prepared analogously to
BrCꢀC-p-C6H4Me. Workups gave 3a and 3b in 48 and
84% yields as analytically pure orange and red–brown
solids.
Other coupling reactions were explored. Per a recent
modification of the Cadiot–Chodkiewicz recipe [22] 2
and ICꢀCSiMe3 were reacted in the presence of excess
pyrrolidine and a catalytic amount of CuI (Scheme 1,
step B). Workup gave 3a in 44% yield. Alternatively,
the iodonium triflate [PhICꢀCSiMe3]+TfO− was pre-
pared [23] and added to a mixture of 2 and n-BuLi
(Scheme 1, step C). Alkynyl iodonium salts have previ-
ously been utilized in alkyne coupling reactions [24].
Workup gave 3a in 50% yield. However, 3b was se-
lected for subsequent preparative studies on the basis of
(1) the superior yield, (2) a greater shelf stability, (3) the
greater shelf stability of the haloalkyne precursor
BrCꢀCSiEt3, and (4) the ease of purification. Impor-
tantly, the incomplete purification of 3a,b results in
workup problems in subsequent steps.
Scheme 2. Syntheses of 1,3,5-hexatriynyl and 1,3,5,7-octatetraynyl
complexes 7 and 8.
Attention was turned to the title compounds. As
shown in Scheme 2, 1a was again converted to 2
(91–84%) and the copper species 4, which was treated
with BrCꢀC-p-C6H4Me in the presence of excess
EtNH2. Workup gave the analytically pure hexatriynyl
tions with 3b gave 8 in 71% yield. In another variant,
3b, n-Bu4N+F− (0.3 equivalents), t-BuOK, and CuI
were combined in THF at room temperature. This
recipe avoids the prior synthesis of t-BuOCu. An IR
spectrum showed the formation of the alkynyl copper
species 6 [19]. Reaction with BrCꢀC-p-C6H4Me as
above gave 8 in 50% yield after workup [26].
complex
(h5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀC-p-
C6H4Me) (7) in 77% yield after crystallization.
Analogous reactions were used to convert 3b to the
parent hexatriynyl complex 5 (88–90%) and then the
copper species (h5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀ
CCu) (6) [19]. A similar reaction with BrCꢀC-p-
C6H4Me gave the 1,3,5,7-octatetraynyl complex (h5-
C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀCCꢀC-p-C6H4Me)(8)
in 66% yield after workup.
Streamlining of the preceding syntheses was at-
tempted. In an attempt to bypass the use of n-BuLi, the
copper alkoxide t-BuOCu was prepared from t-BuOLi
and CuCl [25]. Then 1a, n-Bu4N+F− (0.2 equivalents),
and t-BuOCu (1.5 equivalents) were combined in THF
at room temperature. An IR spectrum showed the clean
formation of the same alkynyl copper species 4 as
generated above. Reaction with BrCꢀC-p-C6H4Me as
above gave 7 in 81% yield after workup. This one pot
sequence gives a significantly higher overall yield than
the two step route (65–70%). A similar series of reac-
The hexatriynyl complexes 3a,b,5,7 and octatetraynyl
complex 8 exhibited distinctive spectroscopic proper-
ties. IR spectra showed the same number of wCꢀC bands
as CꢀC linkages (2180–1970 cm−1), and wNO values
close to those of alkynyl complexes of I (1659–1650
cm−1). The ReCꢀC 13C-NMR signals appeared at
2
(CD2Cl2, ppm) 119.9–112.3 (d, JCP 16.4–15.1 Hz) and
3
112.8–111.2 (s, JCPB2 Hz), respectively. The
ReCꢀC(CꢀC)nCꢀCX signals clustered in the range of
61.4–70.0 ppm, a phenomenon analyzed previously
[6,12b]. The ReCꢀCC peaks generally showed phospho-
4
rus coupling (d, JCP 3.8–2.4 Hz), as observed with
lower homologs earlier [17]. The CꢀCSi 13C-NMR sig-
nals appeared at 92.7–92.2 and 86.3–83.7 ppm, while
the CꢀC-p-C6H4Me signals were at 78.2–78.0 and
75.5–74.9 ppm. Mass spectra exhibited intense molecu-
lar ions. The UV–visible spectra of 7 and 8 are shown

232
R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
Table 1
in Fig. 1. As expected, absorptions shift to longer
wavelengths and become more intense with increasing
chain length. The strongest band of 8 has an exception-
ally high molar extinction coefficient, 89 000
Summary of crystallographic data for 7 and 8a
7
8
M
−1cm−1. DSC measurements show that 7 and 8
Molecular formula
Molecular weight
Crystal system
C41H37NOPRe
776.89
Monoclinic
P21/c
C43H37NOPRe
800.91
Monoclinic
P21/n
gradually decompose without melting at 181–193°C.
Space group
Temperature of collection
(K)
120(1)
120(1)
2.2. Crystallography
Cell dimensions (120(1) K)
˚
a (A)
17.951(8)
8.377(5)
22.160(9)
103.63(5)
3239(3)
4
1.593(1)
0.2×0.2×0.04
5115
8.426(3)
16.400(6)
25.400(9)
97.51(3)
3480(3)
4
1.529(1)
0.26×0.16×0.07
5674
The crystal structures of 7 and 8 were determined as
outlined in Table 1 and described in the experimental
section. Refinement afforded the structures in Fig. 2.
Selected bond lengths and angles are listed in Table 2,
and atomic co-ordinates are given in Table 3. Both sp
carbon chains are conspicuously bent. The overlay in
Fig. 2 shows that 7 exhibits greater curvature. In order
to provide a solid foundation for analysis, the more
routine structural features are presented first.
˚
b (A)
˚
c (A)
i (°)
3
˚
V (A )
Z
Dcalc (g cm−3) (120(1) K)
Crystal dimensions (mm)
Reflections measured
Range/indices (h, k, l)
−22, 21; 0, 10;
0, 27
−10, 10; 0, 20;
0, 31
Both 7 and 8 exhibit a formally octahedral rhenium
co-ordination geometry, with the cyclopentadienyl lig-
and occupying three sites. Accordingly, the N–Re–P,
P–Re–C41, and N–Re–C41 angles are near 90°
(90.2(3)–98.6(5)°). The Re–C41 bond lengths
q limit (°)
2.33–26.06
4976
2563
2.04–26.05
5582
3274
Total no. of unique data
No. of observed data,
I\2|(I)
Abs. Coefficient (mm−1
Min. transmission (%)
Max. transmission (%)
No. of variables
)
3.84
0.494
0.858
396
3.57
0.534
0.763
424
˚
(1.998(12) and 2.016(8) A) are quite close to that in the
1,3,5,7-tetrayne (h5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀ
Goodness of fit (all, ob-
served)
Rint
1.004, 1.195
1.007, 1.167
˚
CCꢀCSiMe3) (2.037(5) A), the essentially linear chain of
which was analyzed in our earlier study [6]. The CꢀC
0.0633
0.1444, 0.0385
0.0230
0.1051, 0.0314
˚
bonds in 8 (1.214(11)–1.242(12) A) fall into a normal
R=SꢀꢀFoꢀ−ꢀFcꢀꢀ/SꢀFoꢀ
range [27]. However, the ReCꢀC linkage in 7 (1.28(2)
(all, observed)
wR2 =(S[w(F2o-Fc2)2]/
Sw[F4o]1/2 (all, observed)
D/| (max)
0.1037, 0.0852
0.001
2.21 (ca. 0.86 A 1.13 (ca. 1.42 A
from Re)
0.0866, 0.0747
˚
A) appears, subject to the larger estimated S.D. value,
to be longer. Both complexes give the short ꢀC–Cꢀ
−0.001
˚
sp/sp single bonds (1.33(2)–1.380(11) A) typical of
−3
˚
˚
˚
Dz (max) (e A
)
polyynes, as discussed previously [6]. Key data for 8
and other crystallographically characterized 1,3,5,7-te-
traynes are summarized in Table 4.
The four sp C–C–C bond angles in 7 range from
171.6(12)° to 178.8(13)°, with an average of 174.2°. The
from Re)
a Data common to both structures: diffractometer, KUMA KM4;
radiation u, Mo–Ka (0.71073 A); data collection method, ꢀ−2q; no.
of reflections between std, 100.
˚
Re–CꢀC linkage is especially bent (169.1(10)°). How-
ever, the CꢀC–tolyl linkage at the opposite terminus is
nearly linear (177.1(12)°). The average of all six angles
is 174.7°. As summarized in Table 4, the Re–CꢀC,
CCC, and CꢀC–tolyl angles in 8 average 175.7°. This is
significantly lower than the corresponding averages in
other structurally characterized tetraynes. The ReCꢀC–
C linkage shows the greatest bending (170.0(9)°, vs.
171.6(12)° in 7). Another way to analyze curvature is to
compare the actual distance between the endgroups
with the sum of the bond lengths connecting them. The
˚
Re(CꢀC)3C termini in 7 are separated by 9.69(2) A, and
˚
the intervening bond lengths total 9.87 A. The corre-
˚
sponding values for 8 are 12.22(1) and 12.42 A. Also,
Fig. 1. UV–visible spectra of 7 and 8 (CH2Cl2, ambient temperature).

R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
233
Table 2
the actual and ‘calculated’ CꢀCCꢀCCꢀCCꢀC distances
Selected bond lengths and angles in 7 and 8
in 8 can be compared with those in other 1,3,5,7-tetray-
nes. As summarized in Table 4, 8 exhibits the largest
7
8
˚
difference to date (8.89(2) vs. 8.97 A).
˚
Bond lengths (A)
The curvature in 7 and 8 was next analyzed by taking
vectors between the Re(CꢀC)nC termini, and computing
angles with vectors defined by the termini and every
atom in the chain. Results are summarized in Fig. 3.
Atoms are bent as much as 17° out of the direct line
connecting the endgroups. The sense of the curvature
continues through the p-tolyl groups, one measure of
which are the angles defined by the two substituted
carbons and the methyl groups (ÚC51–C54–C57:
177.3°, 177.8°). We were also curious about how the
C41–Re–C51 angles would change when C41 was
moved to an idealized octahedral position with respect
Re–P
Re–N
N–O
Re–C41
Re–C1
Re–C2
Re–C3
Re–C4
Re–C5
2.366(3)
1.799(10)
1.163(11)
1.998(12)
2.333(12)
2.375(11)
2.357(11)
2.278(11)
2.248(10)
1.831(12)
1.848(10)
1.826(11)
1.28(2)
1.35(2)
1.23(2)
1.33(2)
1.22(2)
1.46(2)
–
2.380(2)
1.761(6)
1.204(8)
2.016(8)
2.309(8)
2.380(6)
2.349(7)
2.263(7)
2.243(8)
1.842(7)
1.831(8)
1.838(8)
1.214(11)
1.380(11)
1.233(11)
1.338(11)
1.242(12)
–
1.337(12)
1.223(11)
1.439(12)
1.360(13)
1.389(11)
1.383(13)
1.376(13)
1.396(13)
1.514(12)
1.388(12)
P–C11
P–C21
P–C31
C41–C42
C42–C43
C43–C44
C44–C45
C45–C46
C46–C51
C46–C47
C47–C48
C48–C51
C51–C52
C51–C56
C52–C53
C53–C54
C54–C55
C54–C57
C55–C56
–
–
1.40(2)
1.39(2)
1.36(2)
1.39(2)
1.35(2)
1.53(2)
1.40(2)
Bond angles (°)
N–Re–P
P–Re–C41
N–Re–C41
Re–N–O
C1–Re–C41
C2–Re–C41
C3–Re–C41
C4–Re–C41
91.1(3)
90.2(3)
98.6(5)
175.9(9)
146.5(4)
114.8(4)
87.9(4)
93.6(4)
129.5(4)
169.1(10)
171.6(12)
176.7(12)
174.7(11)
178.8(13)
177.1(12)
–
91.4(2)
92.0(2)
95.5(3)
175.5(6)
147.9(3)
115.7(3)
88.5(3)
93.5(3)
128.1(3)
174.5(7)
170.0(9)
176.9(9)
173.6(10)
178.1(10)
–
C5–Re–C41
Re–C41–C42
C41–C42–C43
C42–C43–C44
C43–C44–C45
C44–C45–C46
C45–C46–C51
C45–C46–C47
C46–C47–C48
C47–C48–C51
C46–C51–C52
C46–C51–C56
C48–C51–C52
C48–C51–C56
C51–C52–C53
C51–C56–C55
C52–C51–C56
C52–C53–C54
C53–C54–C55
C53–C54–C57
C54–C55–C56
C55–C54–C57
C11–P–C21
177.6(10)
178.8(10)
175.8(10)
–
–
–
119.2(12)
122.0(11)
–
–
122.3(8)
119.1(9)
121.6(9)
119.6(9)
118.6(8)
121.6(10)
116.5(9)
119.9(9)
122.1(9)
123.6(9)
103.0(3)
98.7(3)
105.6(3)
–
120.1(12)
118.3(12)
118.7(11)
122.5(11)
116.2(11)
120.3(13)
124.1(14)
123.4(14)
103.3(5)
96.5(5)
105.8(5)
C11–P–C31
C21–P–C31
Fig. 2. Structures of 7 (top), 8 (middle), and a superposition (bottom).

234
R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
to the N–Re–P plane. We had expected that values
would increase, analogous to taking a bent metal saw and
releasing one end to re-establish the planar equilibrium
state. To our surprise, the angles decreased from 17.7(3)
and 17.08(21)° to 11.10 and 11.28°.
identified, various possibilities were probed. For exam-
ple, the resonance relationship IIlIII in Scheme 3 was
considered. Zwitterionic vinylidene resonance contribu-
tors such as III have often been invoked to account for
the pronounced nucleophilicity of the beta carbon of
many neutral alkynyl complexes [28]. In extreme cases,
bending might occur as in IV. The structures of vinyli-
Although we were not optimistic that a simple ‘one
parameter’ explanation for chain curvature could be
Table 3
Atomic coordinates and equivalent isotropic thermal parameters of located atoms in 7 and 8
7
8
x
y
z
Ueq
y
z
Ueq
Re
P
N
O
C1
C2
C3
C4
C5
C6
C7
C8
0.61843(3)
0.72854(13)
0.5798(5)
0.5513(5)
0.5547(7)
0.6152(7)
0.6044(6)
0.5360(6)
0.5065(6)
0.5416(7)
0.6741(6)
0.6495(6)
0.4998(7)
0.4313(6)
0.7727(6)
0.7995(6)
0.8453(6)
0.8615(6)
0.8334(6)
0.7890(7)
0.7065(6)
0.7371(6)
0.7127(7)
0.6603(6)
0.6293(6)
0.6511(5)
0.8162(6)
0.8801(6)
0.9491(6)
0.9525(6)
0.8906(6)
0.8218(5)
0.6763(6)
0.7092(6)
0.7473(6)
0.7825(7)
0.8197(6)
0.8525(7)
–
0.66994(7)
0.6625(4)
0.62635(2)
0.70960(10)
0.6557(4)
0.6751(4)
0.6450(5)
0.6187(5)
0.5585(5)
0.5456(5)
0.6011(4)
0.7062(5)
0.6472(5)
0.5115(5)
0.4846(5)
0.6081(6)
0.7362(5)
0.6942(6)
0.7154(6)
0.7761(5)
0.8183(6)
0.7980(5)
0.7804(4)
0.8060(5)
0.8573(5)
0.8814(5)
0.8544(5)
0.8029(4)
0.7013(5)
0.7497(5)
0.7413(5)
0.6836(5)
0.6342(5)
0.6420(4)
0.5714(5)
0.5405(5)
0.5158(4)
0.4958(5)
0.4787(5)
0.4632(5)
–
0.01456(12)
0.0138(5)
0.018(2)
0.031(2)
0.023(3)
0.015(3)a
0.021(3)
0.026(3)
0.021(2)a
0.028(3)
0.023(3)
0.021(3)
0.026(3)
0.032(3)
0.020(3)
0.022(3)
0.028(3)
0.025(3)
0.023(3)
0.026(3)
0.010(2)
0.020(3)
0.025(3)
0.022(3)
0.026(3)
0.018(2)
0.016(2)
0.021(3)
0.025(2)
0.023(3)
0.026(3)
0.014(2)
0.023(3)
0.025(3)
0.020(3)
0.020(3)
0.022(3)
0.023(3)
–
0.73341(3)
0.7878(2)
0.5695(7)
0.4613(6)
0.9520(9)
1.0064(7)
0.9146(8)
0.8001(8)
0.8246(9)
1.0351(9)
1.1504(9)
0.9318(11)
0.6973(8)
0.7432(10)
0.6173(8)
0.4894(8)
0.3730(9)
0.3788(9)
0.5036(10)
0.6202(9)
0.9046(7)
1.0607(8)
1.1454(9)
1.0715(10)
0.9152(10)
0.8342(9)
0.8949(8)
0.9407(9)
1.0118(9)
1.0418(9)
0.9981(8)
0.9228(8)
0.6046(8)
0.5159(9)
0.3964(10)
0.2875(10)
0.1591(10)
0.0400(10)
0.52137(2)
0.56088(12)
0.4616(4)
0.4165(4)
0.4422(6)
0.5266(6)
0.5651(5)
0.5062(5)
0.4308(5)
0.3755(5)
0.5612(6)
0.6506(6)
0.5240(6)
0.3511(5)
0.5767(5)
0.6244(5)
0.6503(5)
0.6275(5)
0.5783(6)
0.5526(5)
0.4818(5)
0.4915(5)
0.4278(5)
0.3522(6)
0.3405(6)
0.4060(5)
0.6569(4)
0.6792(5)
0.7532(5)
0.8053(5)
0.7849(5)
0.7111(5)
0.6232(5)
0.6803(5)
0.7380(5)
0.7888(5)
0.8375(5)
0.8826(5)
0.9290(5)
0.9704(6)
1.0240(6)
1.1025(7)
1.1522(6)
1.1241(6)
1.0438(6)
0.9939(6)
1.1798(7)
0.619208(11)
0.70994(8)
0.6324(2)
0.6392(2)
0.6067(3)
0.6045(3)
0.5622(3)
0.5363(3)
0.5642(3)
0.6418(3)
0.6385(3)
0.5420(3)
0.4845(3)
0.5503(4)
0.7474(3)
0.7239(3)
0.7536(3)
0.8063(3)
0.8288(3)
0.7990(3)
0.7484(2)
0.7718(3)
0.7972(3)
0.7997(3)
0.7764(4)
0.7508(3)
0.7268(3)
0.7798(3)
0.7926(3)
0.7526(4)
0.7007(3)
0.6878(3)
0.6003(3)
0.5877(3)
0.5782(3)
0.5721(3)
0.5676(3)
0.5651(3)
0.5638(3)
0.5632(3)
0.5638(3)
0.5465(4)
0.5456(4)
0.5607(3)
0.5790(4)
0.5808(3)
0.5574(4)
0.01737(8)
0.0183(4)
0.021(2)
0.0346(15)
0.023(2)
0.022(2)
0.021(2)
0.024(2)
0.027(2)
0.031(2)
0.033(2)
0.037(2)
0.032(2)
0.035(2)
0.019(2)
0.023(2)
0.027(2)
0.026(2)
0.037(2)
0.032(2)
0.0181(14)
0.022(2)
0.028(2)
0.033(2)
0.036(2)
0.031(2)
0.020(2)
0.023(2)
0.028(2)
0.030(2)
0.028(2)
0.022(2)
0.021(2)
0.026(2)
0.028(2)
0.028(2)
0.031(2)
0.035(2)
0.033(2)
0.035(2)
0.030(2)
0.050(3)
0.046(3)
0.036(2)
0.046(3)
0.040(2)
0.049(3)
0.4960(12)
0.3893(10)
0.9009(15)
0.9527(13)
0.8904(14)
0.7921(14)
0.8026(14)
0.9583(15)
1.0804(14)
0.9236(13)
0.7216(14)
0.7311(15)
0.4701(14)
0.3782(13)
0.2460(15)
0.2034(13)
0.2897(12)
0.4275(16)
0.7476(13)
0.8878(14)
0.9505(15)
0.8681(13)
0.7296(15)
0.6738(18)
0.7614(13)
0.7698(13)
0.8275(18)
0.8859(13)
0.8756(13)
0.8123(15)
0.5608(15)
0.4669(15)
0.3554(15)
0.2489(14)
0.1257(14)
0.0114(15)
C9
C10
C11
C12
C13
C14
C15
C16
C21
C22
C23
C24
C25
C26
C31
C32
C33
C34
C35
C36
C41
C42
C43
C44
C45
C46
C47
C48
C51
C52
C53
C54
C55
C56
C57
–
–
–0.0909(10)
–0.2118(10)
–0.3467(8)
–0.3455(12)
–0.4785(12)
–0.6194(11)
–0.6193(12)
–0.4855(10)
–0.7636(12)
–
–
–
0.8942(7)
0.9630(7)
1.0044(7)
0.9791(7)
0.9129(8)
0.8685(8)
1.0285(9)
–0.1256(15)
–0.1009(15)
–0.2278(15)
–0.3846(16)
–0.4056(18)
–0.2808(16)
–0.5225(18)
0.4476(5)
0.4298(5)
0.4176(6)
0.4187(5)
0.4363(5)
0.4510(6)
0.4054(6)
0.028(3)
0.024(3)
0.031(3)
0.030(3)
0.040(4)
0.036(4)
0.049(4)
a Refinement as Uiso
.

R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
235
Table 4
Summary of bond lengths (A) and bond angles (°) for crystallographically characterized 1,3,5,7-tetraynes XCꢀCCꢀCCꢀCCꢀCX%
a
˚
X/X%
Ph/Phb Ph/CꢀCPhc
t-Bu/t-Bu
Me3Si/Me3Si
Cycbu/Cycbud Ree/SiMe3 Fc/Fcf
Ree/ p-tolyl (8)
˚
Bond lengths (A)
C1–C2
C2–C3
C3–C4
C4–C5
C5–C6
C6–C7
C7–C8
C1–C8 distance
sum
1.19
1.36
1.22
1.32
1.22
1.36
1.19
–
1.192
1.369
1.206
1.368
1.208
1.368
1.206
8.915
1.217(9)
1.377(9)
1.172(8)
1.351(9)
1.218(9)
1.36(1)
1.202(8)
8.87
1.20(1)
1.39(1)
1.20(1)
1.33(1)
1.20(1)
1.378(9)
1.209(9)
8.88
1.19(2)
1.38(3)
1.18(2)
1.38(4)
1.18(2)
1.38(3)
1.19(2)
8.86
1.208(9)
1.35(1)
1.21(1)
1.36(1)
1.194(9)
1.37(1)
1.20(1)
8.872(9)
1.19(1)
1.38(1)
1.188(9)
1.37(1)
1.188(9)
1.38(1)
1.19(1)
8.88
1.214(11)
1.380(11)
1.233(11)
1.338(11)
1.242(12)
1.337(12)
1.223(11)
8.89(2)
C1–C8 bond lengths
8.86
8.917
8.90
8.91
8.88
8.89
8.88
8.97
Bond anglesb (°)
X–C1–C2
–
–
–
–
–
–
–
–
178.08(6)
178.49
178.30
178.67
178.52
178.52
178.67
178.30
178.4
178.8(6)
177.6(6)
178.5(5)
177.4(6)
176.7(6)
178.9(6)
176.1(6)
179.4(6)
177.9
178.1(6)
177.7(8)
177.4(7)
177.8(8)
176.9(8)
178.4(7)
178.6(7)
177.2(6)
177.8
176(2)
177(3)
179(3)
174(3)
174(3)
179(3)
177(3)
176(2)
176.7
[9]
176.4(6)
177.4(8)
178.2(8)
176.4(8)
178.9(8)
175.9(8)
179(1)
178.0(9)
177.5
[6]
179.5(5)
177.9(6)
179.6(6)
179.6(6)
179.6(6)
179.6(6)
177.9(6)
179.5(5)
179.2
174.5(7)
170.0(9)
176.9(9)
173.6(10)
178.1(10)
177.6(10)
178.8(10)
175.8(10)
175.7
C1–C2–C3
C2–C3–C4
C3–C4–C5
C4–C5–C6
C5–C6–C7
C6–C7–C8
C7–C8–X%
Average angle
Reference
–
[7]
[11]
[4b]
[8]
[10]
This work
a All estimated S.D. values are as reported in the citation provided, or rounded downward by one significant digit.
b No bond angles or atomic co-ordinates were reported for X/X%=Ph/Ph.
c
˚
˚
Additional data for diphenyl 1,3,5,7,9-pentayne: C8–C9 1.369 A; C9–C10 1.192 A; ÚC8–C9–C10 178.49°; ÚC9–C10–Ph 178.08(6)°.
¸¹¹¹¹¹¹¹¹¹¹¹¹¹¹º
d Cycbu=(h5-C5H5)Co(h4-C(SiMe3)ꢁC(SiMe3)–C(SiMe3)ꢁC–).
e Re=(h5-C5Me5)Re(NO)(PPh3).
f Fc=ferrocene.
dene complexes of I or cyclopentadienyl homologs
have been extensively studied [29–32]. As would be
expected from the rhenium fragment HOMO (Scheme
3) and frontier orbital considerations, they exhibit
ReꢁCꢁC conformations very close to that of the ide-
alized structure V. Thus, one question is whether the
chains in 7 or 8 curve in the direction of the ReꢁCꢁC
substituents in V.
Fig. 4 shows the corresponding Newman-type pro-
jections down the C42–Re vectors of 7 and 8. The
P–Re–C42–C43 torsion-type angles in V are 0 and
180°. The corresponding angles in 7 and 8 are
Scheme 3. Possible resonance issues in chain bending.
Scheme 4. Protonation of 7.

236
R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
Fig. 3. Angles (°) defined by the Re–C51 vectors and sp carbon atoms in 7 (top) and 8 (bottom).
roughly orthogonal (62.4–83.8°). Hence, the curvature
does not have a stereoelectronic origin. We next care-
fully studied the crystal packing, and among the many
views examined found those in Figs. 5 and 6 instructive.
These show infinite stacks, with the tolyl rings in ap-
proximate edge-on orientations. The sp carbon chains
curve away from the phenyl rings of a stack of PPh3
ligands, and towards a complementary stack of sp
carbon chains. The tolyl endgroups of the two stacks
are in close proximity, and define approximately paral-
agents, for which the possibility of rapid and reversible
addition would be greater.
As shown in Scheme 4, the hexatriyne 7 and an
equimolar amount of HBF4·OEt2 were combined in
CD2Cl2 in an NMR tube at −80°C. Both 1H- and
31P-NMR spectra showed the formation of two species
with closely corresponding chemical shifts in a (879
2):(1392) ratio (−80°C, major/minor: 1H (l) 5.92/
5.98 ꢁCꢁCH, 2.30/2.33 C6H4Me, 1.87/1.90 C5Me5; 31P
1
(ppm) 25.2/25.5). The l 5.92/5.98 H signals were close
to those of vinylidene and isomeric methylvinylidene
complexes of I prepared earlier (ReꢁCꢁCHH%, l
5.28, 4.95, CDCl3; ReꢁCꢁC(H)CH3, l 5.91/5.61 ac/sc,
CD2Cl2; these data at ambient probe temperature)
[31,32]. When samples were warmed to room tempera-
ture, equilibration to (6092):(4092) mixtures of iso-
mers occurred. This ratio remained unchanged after
two days, or when samples were recooled to −80°C.
The fact that the kinetic ratio differs from thermody-
namic ratio suggests that the protonation is under
kinetic control.
˚
lel planes separated by 3.0–3.5 A. However, the tolyl
groups lie nearer to the terminal CꢀC linkage of the
complementary chain. From these data, we suggest that
crystal packing forces provide the dominant basis for
chain curvature.
2.3. Protonation of 7
The preceding analysis suggests that the chain curva-
ture evident in Figs. 2–6 may not exist in solution.
Nonetheless, we were curious about possible reactivity
correlations. As noted above, electrophiles attack
alkynyl complexes of I at the beta carbon to give
cationic vinylidene complexes [29,32] With longer
polyalkynyl chains as in 7 and 8, would attack involve
a carbon remote from the bulky rhenium center, or the
potentially distorted region nearer to rhenium? We were
unable to develop any clean reactions with alkylating
agents, for which there would be a high probability of
kinetic control. Hence, we turned to protonating
Workup of a preparative reaction gave a yellow
powder that was provisionally assigned as a mixture of
ReꢁCꢁC geometric isomers of the vinylidene complex
[(h5 - C5Me5)Re(NO)(PPh3)(CꢁC(H)CꢀCCꢀC - p - C6H4-
Me)]+BF4− (9, 84%). Complex 9 was characterized by
1
IR and H-, 13C-, and 31P-NMR spectroscopy, all of
which supported the proposed formulation. For exam-
1
ple, the ReꢁCꢁCH H-NMR signals showed phospho-
rus couplings similar to those of other vinylidene
complexes of I (CD2Cl2, major/minor: l 5.88/5.73, d,

R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
237
an ac isomer entails protonation from a direction op-
posite to the bulky PPh3 ligand. This provides an-
other argument that the chain proton in 9 is not at a
more remote location, as lower stereoselectivity would
have been expected. In the cyclopentadienyl series, the
thermodynamic isomer is opposite from the kinetic
isomer. However, in the pentamethylcyclopentadienyl
series, the substituent positions appear to be com-
parably congested. Accordingly, the methylvinylidene
complex of I gives a (5792):(4392) equilibrium
mixture of ac/sc isomers [31].
We sought to confirm the structure of 9 crystallo-
graphically. The corresponding PF6− and SbF6− salts
were generated by the reaction of 7 and HBF4·OEt2
in the presence of the excesses of NH4+PF6− and
Na+SbF6−. However, numerous efforts to obtain sin-
gle crystals were unsuccessful. Such difficulties are not
unusual with mixtures of geometric isomers. Hence,
we attempted to establish the position of the chain
proton by 2D NMR methods, under conditions de-
scribed in Section 4.
1
As shown in Fig. 7 (top), a H-13C-HMQC experi-
ment [34] correlated the l 5.88 and 5.73 1H signals
(d, ac/sc) to the 112.2 and 112.8 ppm 13C signals (the
1H signals in the 1D spectrum fall in the midpoint of
the 13C-coupled cross peaks). As noted above, the
latter can confidently be assigned to the ReꢁCꢁC car-
bons based upon chemical shift and JCP values. This
experiment confirms that the carbon and hydrogen
atoms responsible for these signals are directly bound.
Supporting HMBC experiments [34] were also con-
ducted. The middle spectrum in Fig. 7 shows that the
l 5.88 1H-NMR signal and 342.7 ppm ReꢁC signal
Fig. 4. Newman-type projections down the C42–Re linkages in 7
(top) and 8 (bottom) with PPh3 phenyl rings omitted.
1
belong to the same isomer, and that the l 5.73 H-
NMR signal and 341.1 ppm ReꢁC signal belong to
the same isomer. This confirms what is otherwise
available from the modestly biased integral ratios.
The bottom spectrum in Fig. 7 provides the same
correlation between the 1H signals and the
ReꢁCꢁC(H)CꢀCCꢀC carbons.
4JHP 2.39/2.04 Hz) [31,32]. The 13C-NMR spectrum
showed diagnostic ReꢁCꢁC signals (342.7/341.1, d,
3
2JCP 10.4/10.8 Hz; 112.2/112.8, d, JCP 4.0/3.8 Hz),
and four peaks that were assigned to the CꢀCCꢀC
linkage (87.0/87.2 s, 86.9/86.3 s, 73.2/73.2 s, 64.8/65.4
s).
Finally, in a particularly demanding experiment, a
2D 13C-INADEQUATE spectrum [35] was acquired
over the course of 5 days at −90°C. This technique
1
The major and minor isomers were tentatively as-
signed the ac and sc geometries shown in Scheme 4.
This was based upon the relative chemical shifts of
the ReꢁCꢁCH 1H-NMR signals at room temperature
[33]. This correlation has been confirmed by crystallo-
graphic and by isotope labeling studies, and is derived
from the shielding effect of a PPh3 phenyl ring
unique to the sc isomer [29,31]. The attack of elec-
trophiles upon the beta carbon of chiral rhenium
alkynyl complexes is commonly highly stereoselective
[29,32]. As analyzed earlier, the initial formation of
provides both carbon connectivity and J13
values.
13
C
Data are summarized graphically in ChartC 1, and
show that the ꢁC(H) carbons are connected to four
carbon chains that terminate with a p-C6H4Me moi-
ety. This unequivocally eliminates the possibility of
+ReꢁCꢁCꢁCꢁC(H)CꢀC or +ReꢁCꢁCꢁCꢁCꢁCꢁC(H)
1
systems. The J13
values within the sp hybridized
13
C
CꢀC–CꢀC segment Care comparable to those of bu-
tadiyne (199–205 and 161 vs. 190–194 and 153–155
Hz) [36]. The values for the sp/sp2 linkages are, as
expected, smaller (92–99 Hz).

238
R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
ing 1,3-butadiynyl complex and employed Sonogashira
conditions—p-iodotoluene, an amine, and a mixed
Cu(I)/Pd(0) catalyst. Other iodoarenes as well as
molybdenum precursors also worked well. We antici-
pate that similar reactions would be successful with our
rhenium complexes. However, couplings in which both
partners have alkynyl segments constitute more conver-
gent approaches to sp carbon chain extension.
The supporting studies in Scheme 1 also illustrate
several important points. Three different coupling reac-
tions (A–C) were evaluated as routes to the trimethylsi-
lyl capped 1,3,5-triene 3a. Although yields were similar,
the Cadiot–Chodkiewicz variant involving a pre-
formed copper alkynyl complex (A) proved superior.
However, in our experience it is difficult to predict in
advance the best recipe for sp/sp carbon–carbon bond
forming reactions, and it is always best to assay several
conditions. This is particularly true for oxidative self-
couplings of terminal alkynes. The discovery that t-
BuOCu is sufficiently basic to deprotonate 2 to 4
simplifies the overall procedure. This reagent similarly
reacts with the ethynyl complex (h5-C5Me5)Re(NO)-
Chart 1.
3. Discussion
Scheme 2 summarizes highly optimized routes to the
title 1,3,5-hexatriynyl and 1,3,5,7-octatetraynyl com-
plexes in which a variant of the Cadiot–Chodkiewicz
reaction plays a pivotal role. In very recent work, Bruce
has prepared a tungsten 1,3-butadiynyl complex with a
p-tolyl endgroup [13c]. He started with the correspond-
Fig. 5. Representative packing diagram for crystalline 7.

R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
239
Fig. 6. Representative packing diagram for crystalline 8.
(PPh3)(CꢀCH), which as analyzed earlier is even less
acidic [17].
(CꢀCCꢀCCꢀCH) suggest that protonation of the ꢀCH
terminus would give the most stable product [37]. This
implicates another, non-thermodynamic, controlling
feature. Regardless, the regiochemistry is somewhat
unfortunate, as we had hoped to use these compounds
as precursors to species with +Reꢁ(CꢁC)n(X)(Ar) link-
ages. Using other synthetic approaches, we have been
able to isolate labile complexes of the formula
+ReꢁCꢁCꢁCꢁCꢁC(Ar)2 [39].
In summary, this study has provided the first demon-
stration that sp carbon chains can exhibit significant
bending or curvature in the solid state. This constitutes
important support for the conjecture that sp carbon
chains might easily coil as they grow under various gas
phase conditions, leading to intramolecular carbon–car-
bon bond formation and ultimately fullerenes. We will
continue to structurally characterize all compounds with
at least eight consecutive sp carbons that we are able
to crystallize, and anticipate the serendipitous discovery
of additional unusual bonding and packing motifs.
We can define no basis for sp carbon chain curvature
in crystalline 7 and 8 other than packing forces. If this
is indeed the dominant factor, then the lack of precedent
among the compounds in Table 4 is surprising. Density
functional calculations (B3LYP/6-31G*) on the model
compound CH3CꢀCCꢀCCꢀC-p-C6H4Me show that only
3–4 kcal mol−1 are required to produce the degree of
bending in Fig. 3 [37]. Also, a search of the Cambridge
crystallographic data base reveals ten structurally char-
acterized triynes [38]. None of these show any apprecia-
ble bending. Hence, they are not discussed here, and
interested readers are referred to a previous analysis of
packing motifs in these compounds [38d]
The correlation of the site of protonation of 7
(Scheme 4) with the region of maximum chain curvature
in the solid state is probably accidental. However,
density functional calculations (B3LYP/LANL2DZ+
p) on the model compound (h5-C5Me5)Re(NO)(PMe3)-

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R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
AgNO3 (Spectrum, 99+%), NBS (Aldrich), n-
Bu4N+F− (Aldrich, Lancaster; 1.0 M in THF/5 wt%
H2O), CuI (Aldrich, 99.999%), EtNH2 (Aldrich, anhy-
drous; 99% or 2.0 M in THF), t-BuOK (Janssen), and
silica gel (J.T. Baker, 60–200 mesh), used as received;
n-BuLi (Acros, 2.5 M in hexane) [40] and HBF4·OEt2
(Aldrich, two similar weight concentrations in ether:
54% HBF4 or 85% HBF4·OEt2) [41], standardized.
Other materials not listed were used as received.
IR and UV–visible spectra were recorded on
Mattson Polaris FT and Hewlett Packard 8452A spec-
trometers. 1D-NMR spectra were obtained on Varian
300 or 500 MHz spectrometers. Mass spectra were
recorded on a Finnigan MAT 95 high resolution instru-
ment. Differential scanning calorimetry (DSC) was con-
ducted on a TA Instruments model 2910 equipped with
software (‘Universal Analysis’) for Ti, Te, and Tp values
[42]. Samples (1–2 mg) were loaded in crimped Al pans
and heated to 300°C at 5°C min−1 under N2. Micro-
analyses were conducted by Atlantic Microlab.
4.2. BrCꢀC-p-C6H4Me [15,16]
A flask was charged with HCꢀC-p-C6H4Me (2.555 g,
22.00 mmol), AgNO3 (1.308 g, 7.700 mmol) and ace-
tone (20 ml). The mixture was stirred. After 20 min,
acetone (100 ml) and NBS (3.920 g, 22.02 mmol) were
added. After 12 h, ether (100 ml) was added. The
mixture (and 2×10 ml ether rinses) were filtered. Ice
water (40 ml) was poured onto the filtrate with stirring.
The water layer was extracted with ether (2×20 ml).
The combined ether layers were dried over Na2SO4.
Solvents were removed by rotary evaporation at room
temperature and the residue was vacuum transferred by
oil pump vacuum to give BrCꢀC-p-C6H4Me (3.076 g,
15.77 mmol, 72%) as a colorless liquid that was stored
in a freezer. The IR and 1H-NMR spectra matched
those previously reported [15a].
IR (cm−1, CH2Cl2) wCꢀC 2201 vs. NMR: 1H (l,
CDCl3, 300 MHz) 7.32 (d, JHH=8.1 Hz, 2H of C6H4),
7.09 (d, JHH=8.1 Hz, 2H of C6H4), 2.33 (s, CH3);
13C{1H} (ppm, CDCl3, 126 MHz) [43] 139.0 (s, i to
C6H4CH3), 132.0 (s, m to C6H4CH3), 129.2 (s, o to
C6H4CH3), 119.7 (s, p to C6H4CH3), 80.3 (s, CꢀCBr),
49.0 (s, CꢀCBr), 21.6 (s, CH3).
Fig. 7. A 1H-13C-HMQC spectrum of 9 (top) and 1H-13C-HMBC
spectra of 9 (middle, bottom). The 1D reference spectra are derived
from different samples.
4. Experimental
4.3. BrCꢀCSiEt3 [16,21]
4.1. General data
The compounds HCꢀCSiEt3 (1.263 g, 9.000 mmol),
AgNO3 (0.380 g, 2.24 mmol), acetone (100 ml), and
NBS (1.869 g, 10.50 mmol) were combined in a proce-
dure analogous to that given for BrCꢀC-p-C6H4Me. An
identical workup gave BrCꢀCSiEt3 as a colorless liquid
(1.406 g, 6.988 mmol, 78%).
Reactions were conducted under N2 atmospheres.
Commercial chemicals were treated as follows: acetone,
distilled from anhydrous CaSO4; THF, ether, benzene,
hexanes, distilled from Na/benzophenone; toluene, dis-
tilled from Na; pyrrolidine, CH2Cl2/CD2Cl2, distilled/
vacuum transferred from CaH2; HCꢀC-p-C6H4Me
(Aldrich, Lancaster), HCꢀCSiEt3 (Farchan, GFS),
IR (cm−1, film/CH2Cl2) wCꢀC 2123/2120 vs. NMR:
1H (l, C6D6, 300 MHz) 0.96 (t, JHH=7.8 Hz, CH2),

R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
241
0.52 (q, JHH=7.8 Hz, CH3); 13C{1H} (ppm, C6D6, 75
MHz) 84.9 (s, CꢀCBr), 62.8 (s, CꢀCBr), 7.6 (s, CH2),
4.7 (s, CH3).
v/v hexane/THF). Two red bands were collected sepa-
rately, and solvents were removed by rotary evapora-
tion. The second residue was 2 (0.0012 g, 0.0018 mmol,
4%). The first was dissolved in a minimum amount
THF (ca 1 ml), and hexane (ca. 15 ml) was added. The
sample was kept at −90°C (4 h). Solvent was decanted
from an orange powder that was dried by oil pump
vacuum to give 3a (0.0125 g, 0.0165 mmol, 44%). (C) A
Schlenk flask was charged with 2 (0.066 g, 0.10 mmol)
and THF (5 ml), and cooled to −45°C. Then n-BuLi
(2.2 M in hexane, 50 ml, 0.11 mmol) and (after 2 h)
solid [PhICꢀCSiMe3]+TfO− (0.045 g, 0.10 mmol) [23]
were added with stirring. After 1 h, the cold bath was
removed. After 0.5 h, solvent was removed by oil pump
vacuum. The residue was extracted with toluene (2×5
ml). The extract was filtered through a 2 cm silica gel
pad. Solvent was removed from the filtrate by oil pump
vacuum. The residue was extracted with boiling hexane
(2×100 ml). The extract was filtered and kept at
−90°C (24 h). Red–brown microcrystals were isolated
by filtration and dried by oil pump vacuum to give 3a
(0.038 g, 0.050 mmol, 50%), m.p. (dec.) 185–188°C
Rf=0.68 [44b].
4.4. (p5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCH) (2) [17]
A
flask was charged with (h5-C5Me5)Re(NO)
(PPh3)(CꢀCCꢀCSiMe3) (1a; [17] 0.162 g, 0.220 mmol)
and THF (20 ml). Then n-Bu4N+F− (1.0 M in THF/5
wt% H2O; 0.044 ml, 0.044 mmol) was added dropwise
with stirring. After 0.5 h, the mixture was filtered
through a 1 cm silica gel pad. Solvent was removed
from the red filtrate by oil pump vacuum. The residue
was dissolved in a minimum of benzene (ca. 3 ml), and
hexane (50 ml) was added. The sample was kept at
−20°C (freezer, 16 h). Dark red–orange microcrystals
of 2 were isolated by filtration and dried by oil pump
vacuum (0.133 g, 0.201 mmol, 91%). The IR and NMR
spectra matched those previously reported [17].
4.5. (p5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀCSiMe3)
(3a)
(A) A Schlenk flask was charged with 2 (0.0900 g,
0.136 mmol), CuI (0.0285 g, 0.150 mmol), and THF (10
ml), and cooled to −45°C (CO2/CH3CN). Then n-
BuLi (2.2 M in hexane; 0.093 ml, 0.20 mmol) was
added with stirring. After 15 min, EtNH2 (ca. 0.6 ml)
and a solution of ICꢀCSiMe3 [20] (0.0403 g, 0.136
mmol) in THF (1 ml; dropwise over 15 min) were
added. The cold bath was removed. After 10 min,
solvent was removed by rotary evaporation. The
residue was extracted with toluene (3×8 ml). The
extracts were filtered through a 1 cm silica gel pad,
which was washed with toluene (2×10 ml). Solvent
was removed from the red filtrate by rotary evapora-
tion. The residue was dissolved in a minimum of THF
(ca. 2 ml), and hexane/THF (5 ml, 3:1 v/v) was added.
The solution was chromatographed on a silica gel
column (20×2 cm; 1:1 v/v hexane/THF). Solvent was
removed from a red fraction by oil pump vacuum. The
orange–red solid was dissolved in a minimum of THF
(ca. 1 ml) and hexane (15 ml) was added. The sample
was kept at −90°C (4 h). The supernatant was de-
canted to give 3a as an orange powder that was dried
by oil pump vacuum (0.0496 g, 0.0653 mmol, 48%).
Anal. Calc. for C37H39NOPReSi: C, 58.55; H, 5.18.
Found: C, 58.48; H, 5.34. (B) A Schlenk flask was
charged with 2 (0.0292 g, 0.0437 mmol), THF (10 ml),
ICꢀCSiMe3 (0.0110 g, 0.0372 mmol) and pyrrolidine
(0.117 g, 1.65 mmol). Then CuI (0.0003 g, 0.0013
mmol) was added with stirring. After 40 min, solvent
was removed by oil pump vacuum. The residue was
dissolved in a minimum of THF (ca. 2 ml), and hexane/
THF was added (3:1 v/v, ca. 5 ml). The mixture was
chromatographed on a silica gel column (10×2 cm; 1:1
IR (cm−1, THF) wCꢀC 2132 m, 2109 m, 1979 vs., wNO
1
1656 vs. NMR: H (l, CD2Cl2/C6D6, 300 MHz) 7.54–
7.40/7.70–7.61+7.05–6.88 (m, 15H/6+9H, 3C6H5),
1.74/1.52 (s, C5(CH3)5), 0.17/0.39 (s, SiMe3); 13C{1H}
(ppm, C6D6, 75 MHz) 135.2 (d, JCP=54.5, i-Ph), 134.6
(d, JCP=10.2 Hz, o-Ph), 130.7 (s, p-Ph), 128.7 (m-Ph)
[45], 113.3 (d, JCP=15.9 Hz, ReCꢀ), 112.8 (s, ReCꢀC),
101.3 (s, C5(CH3)5), 92.2, 86.3 (2 s, CꢀCSi), 66.5, 63.8
(2 s, ReCꢀCCꢀC), 10.3 (s, C5(CH3)5), 0.5 (s, SiCH3);
31P{1H} (ppm, CD2Cl2/C6D6, 121 MHz) 23.3/19.7 (s).
UV–vis (8.7×10−5 M) [46] 236 (21700), 268 sh
(13600), 288 sh (14600), 300 sh (16000), 312 (17800),
380 sh (6000), 410 sh (4400). MS (positive FAB, 3-
NBA/THF) [47] 759 (M+, 100%), 614 ((h5-
C5Me5)Re(NO)(PPh3)+, 36%); no other peaks above
300 of \10%.
4.6. (p5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀCSiEt3) (3b)
(A) A Schlenk flask was charged with 2 (0.250 g,
0.378 mmol), t-BuOCu [25] (0.052 g, 0.38 mmol), and
THF (50 ml). The mixture was stirred for 2 h and
cooled to –20°C. Then EtNH2 (0.4 ml) and a solution
of BrCꢀCSiEt3 (0.0829 g, 0.378 mmol) in THF (0.5 ml;
dropwise over 15 min) were added. The cold bath was
removed. After 0.5 h, solvent was removed by rotary
evaporation. The residue was extracted with toluene
(3×10 ml). The extract was filtered through a 7 cm
silica gel pad. Solvent was removed from the filtrate by
oil pump vacuum. The residue was dissolved in a
minimum of THF (ca. 2 ml), and hexane was added (5
ml). The solution was chromatographed on a silica gel
column (10×2 cm; 3:1 v/v hexane/THF). Solvent was

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R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
removed from a red fraction by oil pump vacuum. The
red–brown solid was extracted with hot hexane (15 ml).
The extract was filtered and kept in a −90°C freezer
(16 h). Red microcrystals of 3b were isolated by filtra-
tion at −80°C (CO2/acetone) and dried by oil pump
vacuum (0.196 g, 0.245 mmol, 65%). (B) A Schlenk
flask was charged with 2 (1.620 g, 2.204 mmol), CuI
(0.4407 g, 2.314 mmol), and THF (150 ml), and cooled
to −45°C (CO2/CH3CN). Then n-BuLi (2.0 M in
hexane; 1.2 ml, 2.3 mmol) was added with stirring.
After 45 min, EtNH2 (ca. 1.5 ml) and a solution of
BrCꢀCSiEt3 (0.5068 g, 2.314 mmol) in THF (5 ml;
dropwise over 15 min) were added. The cold bath was
removed. After 10 min, solvent was removed by rotary
evaporation. The residue was extracted with benzene
(3×8 ml). The extract was filtered through a 2 cm
silica gel pad, which was washed with benzene (2×10
ml). Solvent was removed from the filtrate by oil pump
vacuum. The residue was dissolved in a minimum of
benzene (ca. 5 ml), and chromatographed on a silica gel
column (25×5 cm; benzene). Solvent was removed
from a red fraction by oil pump vacuum. The red–
brown solid was dissolved in hot hexane (50 ml), and
red microcrystals of 3b were obtained as in procedure A
(1.478 g, 1.845 mmol, 84%), m.p. 182°C. Rf=0.73
[44b]. Anal. Calc. for C40H45NOPReSi: C, 59.98; H,
5.66. Found: C, 60.01; H, 5.66.
extract was filtered through a 1 cm Celite pad. Solvent
was removed from the red filtrate by oil pump vacuum.
The residue was dissolved in minimum of THF, and
hexane (10 ml) was added. Solvent was removed by oil
pump vacuum to give 5 as a reddish brown powder
(0.036 g, 0.045 mmol, 90%), m.p. (dec.) 160–165°C.
Anal. Calc. for C34H31NOPRe: C, 59.46; H, 4.55.
Found: C, 59.46; H, 4.60.
IR (cm−1, THF) wCꢀC 2140 s, 2080 m, 1970 m, wNO
1
1658 vs. NMR: H (l, C6D6, 300 MHz) 7.69–7.62 (m,
6H of 3C6H5), 7.05–6.88 (m, 9H of 3C6H5), 1.69 (s,
ꢀCH), 1.52 (s, C5(CH3)5); 13C{1H} (ppm, CD2Cl2, 75
MHz) 135.0 (i-Ph) [45], 134.3 (d, JCP=10.7 Hz, o-Ph),
130.8 (s, p-Ph), 128.7 (d, JCP=10.3 Hz, m-Ph), 113.6
(d, JCP=15.4 Hz, ReCꢀC), 111.2 (s, ReCꢀC), 101.7 (s,
C5(CH3)5), 70.3 (s, CꢀCH), 68.4 (s, ꢀCH), 63.7 (d,
J
CP=2.8 Hz, ReCꢀCC), 61.5 (s, CCꢀCH), 10.3 (s,
C5(CH3)5); 31P{1H} (ppm, toluene, 121 MHz) 21.0 (s).
UV–vis (2.9×10−5 M) [46] 266 sh (28400), 282 sh
(33300), 304 (35100), 360 (7800), 394 (4000). MS (posi-
tive FAB, 3-NBA/CH2Cl2) [47] 687 (M+, 100%), 614
((h5-C5Me5)Re(NO)(PPh3)+, 14%); no other peaks
above 400 of \10%.
4.8. (p5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀC-
p-C6H4Me) (7)
IR (cm−1, THF) wCꢀC 2132 m, 2110 m, 1979 vs., wNO
(A) A Schlenk flask was charged with 2 (0.508 g,
0.767 mmol), CuI (0.146 g, 0.767 mmol), and THF (50
ml), and cooled to −45°C (CO2/CH3CN). Then n-
BuLi (2.2 M in hexane; 0.35 ml, 0.77 mmol) was added
with stirring. After 20 min the mixture was transferred
to a −20°C bath. Then EtNH2 (ca. 1.0 ml) and a
solution of freshly distilled BrCꢀC-p-C6H4Me (0.150 g,
0.767 mmol) in THF (5 ml; dropwise over 15 min) were
added. After 10 min, the cold bath was removed.
Solvent was removed by rotary evaporation. The
residue was extracted with benzene (3×15 ml). The
extract was filtered through a 2 cm silica gel pad.
Solvent was removed from the bright red–orange
filtrate by oil pump vacuum. The residue was chro-
matographed on a silica gel column (15×2 cm; 2:1 v/v
hexane/THF). Solvent was removed from a red fraction
by oil pump vacuum. The residue was dissolved in a
minimum of toluene (ca. 1.5 ml), and hexane was added
(20 ml). The mixture was kept at −90°C (16 h). Dark
red crystals of 7 were collected by filtration at −80°C
and dried by oil pump vacuum (0.459 g, 0.591 mmol,
77%). (B) A Schlenk flask was charged in an inert
atmosphere box with 1a (0.250 g, 0.341 mmol), t-
BuOCu (0.061 g, 0.44 mmol) and THF (50 ml). Then
n-Bu4N+F− (1.0 M in THF/5 wt% H2O, 0.068 ml,
0.068 mmol) was added with stirring. After 1.5 h, an IR
spectrum showed the absence of 1a and 2 [19]. The
mixture was cooled to −20°C. Then EtNH2 (ca. 0.7
1
1658 vs. NMR: H (l, C6D6, 300 MHz) 7.71–7.59 (m,
6H of 3C6H5), 7.06–6.92 (m, 9H of 3C6H5), 1.52 (s,
C5(CH3)5), 0.99 (t, JHH=8.1 Hz, 3CH2CH3), 0.55 (q,
J
HH=8.1 Hz, 3SiCH2); 13C{1H} (ppm, C6D6, 75 MHz)
134.9 (d, JCP=51.6 Hz, i-Ph), 134.2 (d, JCP=10.5 Hz,
o-Ph), 130.3 (s, p-Ph), 128.5 (m-Ph) [45], 112.5 (s,
ReCꢀC), 112.3 (d, JCP=16.4 Hz, ReCꢀC), 100.0 (s,
C5(CH3)5), 92.7, 83.7 (2 s CꢀCSi), 65.4 (d, JCP=3.6
Hz, ReCꢀCC), 63.6 (s, CCꢀCSi), 9.8 (s, C5(CH3)5), 7.7
(s, SiCH2CH3), 4.9 (s, SiCH2); 31P{1H} (ppm, C6D6/
THF, 121 MHz) 20.5/20.9 (s). UV–vis (1.7×10−5 M)
[46] 234 (92400), 266 (54800), 288 sh (65100), 312
(88100), 370 (15300), 408 (7000). MS (EI, 30 eV) [47]
801 (M+, 43%), 262 (PPh3+, 100%); no other peaks
above 200 of \5%.
4.7. (p5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀCH) (5)
(A) Complex 3b (0.0980 g, 0.122 mmol), n-
Bu4N+F− (1.0 M in THF/5 wt% H2O; 0.036 ml, 0.036
mmol), and THF (20 ml) were combined in a procedure
analogous to that given for 2. An identical workup gave
5 as a red powder (0.0738 g, 0.107 mmol, 88%). (B) A
Schlenk flask was charged with 3b (0.040 g, 0.050
mmol), freshly ground K2CO3 (0.007 g, 0.05 mmol),
and MeOH (5 ml). The mixture was stirred vigorously.
After 24 h, solvent was removed by oil pump vacuum.
The residue was extracted with THF (2×3 ml). The

R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
243
ml) and a solution of BrCꢀC-p-C6H4Me (0.066 g, 0.34
mmol) in THF (5 ml; dropwise over 15 min) were
added. After 0.5 h, solvent was removed by rotary
evaporation. The residue was extracted with benzene
(3×15 ml). The extract was filtered through a 2 cm
silica gel pad. Solvent was removed from the filtrate by
rotary evaporation. The residue was chromatographed
on a silica gel column (25×2 cm; 3:1 v/v hexane/THF).
Solvent was removed from a red fraction by oil pump
vacuum. The residue was dissolved in a minimum of
toluene (ca. 3 ml), and hexane (30 ml) was added. The
mixture was kept at −90°C (16 h) and 7 was collected
as above (0.215 g, 0.277 mmol, 81%). DSC (Ti/Te/Tp)
[42] 170/193/211°C. Anal. Calc. for C41H37NOPRe: C,
63.38; H, 4.80. Found: C, 63.30; H, 4.64. Rf=0.70
[44a]/0.59 [44b].
of benzene (ca. 3 ml) and passed through a silica gel
column (15×2 cm, benzene). A red band was collected,
concentrated by rotary evaporation, and chro-
matographed on a silica gel column (30×2 cm; 2:1 v/v
hexane/THF). Solvent was removed from a red fraction
by oil pump vacuum to give 8 as a reddish–brown
powder (0.2187 g, 0.2731 mmol, 66%). (B) A Schlenk
flask was charged with 3b (0.141 g, 0.176 mmol) and
THF (40 ml). Then n-Bu4N+F− (1.0 M in THF/5 wt%
H2O, 0.053 ml, 0.053 mmol) was added with stirring.
After 0.5 h, t-BuOCu (0.036 g, 0.26 mmol) was added
and the mixture was stirred for 2 h. The mixture was
cooled to −20°C. Then EtNH2 (ca 0.7 ml) and a
solution of BrCꢀC-p-C6H4Me (0.034 g, 0.18 mmol) in
THF (1.5 ml; dropwise over 15 min) were added. After
10 min, the cold bath was removed. Solvent was re-
moved by rotary evaporation. The residue was ex-
tracted with benzene (3×15 ml). The extract was
filtered through a 2 cm silica gel pad. Solvent was
removed from the filtrate by rotary evaporation. The
residue was chromatographed on a silica gel column
(20×2 cm; 3:1 v/v hexane/THF). Solvent was removed
from a red fraction by oil pump vacuum. The residue
was dissolved in a minimum of toluene (ca. 3 ml), and
hexane (50 ml) was added. The mixture was kept at
−90°C (16 h). A dark red powder was collected by
filtration at −80°C and dried by oil pump vacuum to
give 8 (0.101 g, 0.125 mmol, 71%). (C) A Schlenk flask
was charged with 3b (0.136 g, 0.170 mmol) and THF
(20 ml). Then n-Bu4N+F− (1.0 M in THF/5 wt% H2O,
0.051 ml, 0.051 mmol) was added with stirring. After
0.5 h, an IR spectrum showed that 3b had been con-
sumed. Then CuI (0.0323 g, 0.170 mmol) and t-BuOK
(0.0210 g, 0.187 mmol) were added. The mixture was
stirred (1 h) and cooled to −60°C (acetone partially
cooled by CO2). Then EtNH2 (ca 0.5 ml) and a solution
of BrCꢀC-p-C6H4Me (0.0331 g, 0.170 mmol) in THF
(1.5 ml; dropwise over 15 min) were added. After 0.5 h,
solvent was removed by oil pump vacuum. The residue
was extracted with toluene (3×5 ml). The extract was
filtered through a 2 cm silica gel pad. Solvent was
removed from the filtrate by rotary evaporation.
Column chromatography on silica gel (30×2 cm; 3:1
v/v hexane/THF) gave two red bands that were col-
lected separately. Solvents were removed by oil pump
vacuum to give 8 as a reddish–brown powder (0.0686
g, 0.0857 mmol, 50%) and (h5-C5Me5)Re(NO)(PPh3)
(CꢀC)6(Ph3P)(ON)Re(h5-C5Me5) (0.0160 g, 0.0117
mmol, 14%) [12b,c]. Dark red microcrystals of 8 were
obtained from CH2Cl2/hexane (−20°C). DSC (Ti/Te/
Tp) [42] 162/181/204°C. Rf=0.76 [44a]. Anal. Calc. for
C43H37NOPRe: C, 64.48; H, 4.66. Found: C, 64.26; H,
5.06.
IR (cm−1, THF) wCꢀC 2161 w, 2114 vs., 1997 m, wNO
1650 vs. NMR: 1H (l, CD2Cl2/C6D6, 500/300 MHz)
7.55–7.48/7.74–7.66 (m, 6H of 3C6H5), 7.46–7.42/
3
7.07–6.93 (m, 9H of 3C6H5), 7.32/7.23 (d, JHH=8.3/
8.0 Hz, 2H of
m to C6H4CH3), 7.12/6.63 (d,
3JHH=7.8/8.0 Hz, 2H of o to C6H4CH3), 2.35/1.91 (s,
3H, CH3), 1.76/1.52 (s, 15H, C5(CH3)5); 13C{1H} (ppm,
CD2Cl2, 126 MHz) 139.4 (s, i to C6H4CH3) [43], 135.2
(s, i-PPh) [45], 134.4 (d, JCP=10.5 Hz, o-PPh), 133.0
(s, m to C6H4CH3) [43], 130.9 (s, p-PPh), 129.6 (s, o to
C6H4CH3) [43], 128.8 (d, JCP=10.5 Hz, m-PPh), 119.9
(s, p to C6H4CH3) [43], 115.8 (d, JCP=16.2 Hz,
ReCꢀC), 111.8 (s, ReCꢀC), 101.8 (s, C5(CH3)5), 78.2,
75.5 (2 s, CꢀC-p-C6H4Me), 70.0 (d, JCP=3.2 Hz,
ReCꢀCC), 61.4 (s, ReCꢀCCꢀC), 21.8 (s, C6H5CH3),
10.3 (s, C5(CH3)5); 31P{1H} (ppm, C6D6, 121 MHz)
20.6 (s). UV–vis (1.4×10−5 M) [46] 232 (52000), 260
sh (42000), 274 (43000), 302 sh (44000), 320 (67000),
358 sh (23000), 388 sh (15000), 416 sh (9500). MS
(positive FAB, 3-NBA/THF) [47] 777 (M+, 100%), 614
((h5-C5Me5)Re(NO)(PPh3)+, 40%); no other peaks
above 400 of \15%.
4.9. (p5-C5Me5)Re(NO)(PPh3)(CꢀCCꢀCCꢀCCꢀC-
p-C6H4Me) (8)
(A) A Schlenk flask was charged with 5 (0.2840 g,
0.4134 mmol), CuI (0.0827 g, 0.4341 mmol) and THF
(50 ml), and cooled to −45°C. Then n-BuLi (2.4 M in
hexane; 0.18 ml, 0.43 mmol) was added with stirring.
After 25 min the mixture was transferred to a −20°C
bath. Then EtNH2 (ca. 0.5 ml) and a solution of
BrCꢀC-p-C6H4Me (0.0847 g, 0.4341 mmol) in THF (5
ml; dropwise over 15 min) were added. The cold bath
was removed. After 10 min, solvent was removed by
rotary evaporation. The residue was extracted with
benzene (3×8 ml). The extract was filtered through a 2
cm silica gel pad, which was washed with benzene
(2×5 ml). Solvent was removed from the filtrate by oil
pump vacuum. The residue was dissolved in a minimum
IR (cm−1, THF) wCꢀC 2180 w, 2119 w, 2070 vs., 1975
1
s, wNO 1659 s. NMR: H (l, CD2Cl2, 300 MHz) 7.54–
3
7.41 (m, 15H of 3C6H5), 7.38 (d, JHH=8.1 Hz, 2H m

244
R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
1
to C6H4CH3), 7.14 (d, 3JHH=8.1 Hz, 2H o to
C6H4CH3), 2.36 (s, 3H, CH3), 1.75 (s, 15H, C5(CH3)5);
13C{1H} (ppm, CD2Cl2, 126 MHz) 140.5 (s, i to
(s). NMR, sc -9: H (l, CD2Cl2, 500 MHz) 7.68–7.16
(m, 3C6H5, C6H4), 5.73 (d, JHP=2.04 Hz, ReꢁCꢁCH),
2.40 (s, C6H4CH3), 2.03 (s, C5(CH3)5); 13C{1H} (ppm,
C6H4CH3) [43], 134.8 (s, i-PPh) [45], 134.4 (d, JCP
10.7 Hz, o-PPh), 133.4 (s, m to C6H4CH3) [43], 131.0 (s,
p-PPh), 129.8 (s, o to C6H4CH3) [43], 128.9 (d, JCP
=
CD2Cl2, 126 MHz; see also Chart 1) 341.1 (d, JCP=
10.8 Hz, ReꢁCꢁC), 141.3 (s, i to C6H4CH3) [43], 133.6
(d, JCP=12.1 Hz, o-PPh), 133.38 (s, m to C6H4CH3)
[43], 133.21 (s, p-PPh), 132.9 (s, o to C6H4CH3) [43],
130.25 (d, JCP=10.5 Hz, m-PPh), 118.3 (s, p to
C6H4CH3) [43], 112.8 (d, JCP=3.2 Hz, ReꢁCꢁC), 111.5
(s, C5(CH3)5), 87.15 (s, CꢀC-p-C6H4Me), 86.3 (s,
ReꢁCꢁCCꢀC), 73.2 (s, CꢀC-p-C6H4Me), 65.4 (s,
ReꢁCꢁCC), 22.0 (s, C6H4CH3), 10.6 (s, C5(CH3)5);
31P{1H} (ppm, CD2Cl2, 121 MHz) 23.1 (s).
=
10.7 Hz, m-PPh), 119.9 (d, JCP=15.1 Hz, ReCꢀC),
118.9 (s, p to C6H4CH3) [43], 112.4 (s, ReCꢀC), 102.1
(s, C5(CH3)5), 78.0, 74.9 (2 s, CꢀC-p-C6H4Me), 67.4 (d,
J
CP=2.4 Hz, ReCꢀCC), 68.3, 63.9, 63.3 (3 s,
ReCꢀCCꢀCCꢀC), 21.9 (s, C6H5CH3), 10.3 (s,
C5(CH3)5); 31P{1H} (ppm, CD2Cl2, 121 MHz) 19.6 (s).
UV–vis (7.5×10−6 M) [46] 232 (56000), 270 (48000),
282 (49000), 294 (49000), 314 (43000), 336 sh (62000),
356 (89000), 404 sh (17000), 432 sh (12000), 472 sh
(8500). MS (positive FAB, 3-NBA/THF) [47] 801 (M+,
100%), 614 ((h5-C5Me5)Re(NO)(PPh3)+, 15%); no
other peaks above 400 of \3%.
4.11. 2D NMR spectra
Data were obtained on a Varian Unity Inova 500
MHz spectrometer without sample spinning. The
HMQC and HMBC data (Fig. 7) were acquired using a
5 mm indirect detection probe and the standard Varian
pulse sequence (26°C; hypercomplex data matrix,
2048×2048 points with 16 transients time averaged per
4.10. [(p5-C5Me5)Re(NO)(PPh3)(CꢁC(H)CꢀCCꢀC-
p-C6H4Me)]+BF−4 (9)
(A) A 5 mm NMR tube was charged with 7 (0.0069
g, 0.0089 mmol) and CD2Cl2 (0.70 ml), capped with a
septum, and cooled in liquid N2. Then HBF4·OEt2 (7.0
M in ether; 1.4 ml, 0.0095 mmol) was added via syringe.
The tube was placed in a −95°C bath (liq. N2/toluene),
shaken, and quickly transferred to a −80°C NMR
probe. Data: see text. (B) A Schlenk flask was charged
with 7 (0.0570 g, 0.0732 mmol), CH2Cl2 (2 ml), and
ether (10 ml), and cooled to −80°C (CO2/acetone).
Then HBF4·OEt2 (5.78 M in ether; 0.013 ml, 0.073
mmol) was added with stirring. After 10 min, the cold
bath was removed. After 0.5 h, solvent was removed by
oil pump vacuum. Ether (10 ml) was added. The yellow
powder was collected by filtration, washed with ether
(3×2 ml), and dried by oil pump vacuum to give 9
(0.0534 g, 0.0618 mmol, 84%) as (6092):(4092) mix-
ture of ac/sc ReꢁCꢁC isomers. Crystallization attempts
involving CH2Cl2 and ether or hydrocarbons were com-
plicated by the competing slow decomposition of 9.
IR (cm−1): KBr, wCꢀC 2204 w, 2106 w, wCꢁC 1647 m,
wNO 1715 s; CH2Cl2, wCꢀC 2212 w, 2206 w, 2110 w, 2106
FID; spectral widths, 5071 and 18 492.8 Hz (1H and 13
C
dimensions); 90° pulse widths, 5.5 and 27.5 ms (1H and
13C channels)). 13C broadband decoupling was not em-
1
ployed. Thus, the H dimension of the top spectrum
exhibits JCH. Delays of 0.9 (relaxation) and 0.3 s (for
suppressing signals from protons not bound to 13C)
were used. The JCH parameter associated with the bird
pulse was set to 140 Hz. The time domain data were
zero filled to a 4096×4096 hypercomplex and multi-
plied by half-Gaussian functions of widths of 0.185 (1H
dimension) and 0.053 s (13C dimension). Identical
parameters and processing were used for HMBC data,
except that the suppression time was set to zero, the
bird pulse was suppressed, and the multibond evolution
1
time between the H 90° and 180° pulses was set to 55
ms, corresponding to a long-range coupling of 9 Hz.
The 2D-INADEQUATE data (Chart 1) were acquired
using a 0.28 M CD2Cl2 solution of 9 (−90°C), and a
standard 5 mm broadband probe and Varian pulse
sequence (inadqt), with maximum sensitivity set for
J
CC=150 Hz (hypercomplex data matrix, 16 384×256
1
w, wNO 1734 vs. NMR, ac-9: H (l, CD2Cl2, 500 MHz)
points (chemical shift and double-quantum dimensions)
with 1024 transients time averaged per FID; spectral
widths, 19 323.7×19 323.7 Hz; 90° pulse width, 16.5 ms;
no relaxation delay). Proton decoupling was achieved
using WALTZ modulation with a 101 ms 90° pulse. The
data were analyzed using the NMRanalyst (FRED,
Varian NMR Instruments) software package [35].
7.68–7.16 (m, 3C6H5, C6H4), 5.88 (d, JHP=2.39 Hz,
ReꢁCꢁCH), 2.38 (s, C6H4CH3), 1.98 (s, C5(CH3)5);
13C{1H} (ppm, CD2Cl2, 126 MHz; see also Chart 1)
342.7 (d, JCP=10.4 Hz, ReꢁCꢁC), 141.1 (s, i to
C6H4CH3) [43], 133.9 (d, JCP=12.1 Hz, o-PPh), 133.40
(s, m to C6H4CH3) [43], 133.23 (s, p-PPh), 132.7 (s, o to
C6H4CH3) [43], 130.16 (d, JCP=11.3 Hz, m-PPh), 118.4
(s, p to C6H4CH3) [43], 112.2 (d, JCP=4.0 Hz,
ReꢁCꢁC), 111.0 (s, C5(CH3)5), 87.02 (s, CꢀC-p-
C6H4Me), 86.9 (s, ReꢁCꢁCCꢀC), 73.2 (s, CꢀC-p-
C6H4Me), 64.8 (s, ReꢁCꢁCC), 21.9 (s, C6H4CH3), 10.4
(s, C5(CH3)5); 31P{1H} (ppm, CD2Cl2, 121 MHz) 22.9
4.12. Crystallography
Dark red prisms of 7 were obtained by the slow
evaporation of a CH2Cl2 solution (30 days). Prisms
were later grown from CH2Cl2/hexane (vapor diffusion,

R. Dembinski et al. / Journal of Organometallic Chemistry 578 (1999) 229–246
245
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2 days), but it was not confirmed whether they were
identical to those characterized crystallographically.
Deep red orthogonal prisms of 8 were obtained from
CH2Cl2/hexane (vapor diffusion, 5 days). Data were
collected as outlined in Table 1 using a KUMA KM4
four-circle diffractometer with an Oxford Cryosystem–
Cryostream cooler. Preliminary data for 8 were ob-
tained from Weissenberg photographs (299(1) K:
a=8.528(3),
b=16.433(5),
c=25.757(9),
i=
97.65(3)°). Cell parameters (120(1) K) were obtained
from 58 reflections with 14°B2qB24°. Space groups
were determined from systematic absences and subse-
quent least-squares refinement. Standard reflections
(monitored every 100 scans) showed no decay. Lorentz,
polarization, and absorption (numerical by use of
SHELX76 [48]) corrections were applied. The struc-
tures were solved by standard heavy atom techniques
with SHELXS and refined with SHELX-93 [49]. Non-
hydrogen atoms were refined with anisotropic thermal
parameters except C2 and C5 of 7, which showed
non-positive definition. Hydrogen atom positions were
calculated and added to the structures factor calcula-
tions, but were not refined. Scattering factors, and Df %
and Df ¦ values, were taken from literature [50].
[6] B. Bartik, R. Dembinski, T. Bartik, A.M. Arif, J.A. Gladysz,
New Journal of Chemistry 21 (1997) 739.
[7] I. Nitta, Acta Crystallogr. 13 (1960) 1035.
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Dalton (1975) 442.
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15 (1996) 5028.
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Diederich, J. Am. Chem. Soc. 113 (1991) 6943.
5. Supplementary material available
[12] References to C8–C20 complexes prepared in our laboratory: (a)
M. Brady, W. Weng, J.A. Gladysz, J. Chem. Soc. Chem. Com-
mun. (1994) 2655. (b) T. Bartik, B. Bartik, M. Jaeger, R.
Dembinski, J.A. Gladysz, Angew. Chem. 108 (1996) 467; Angew.
Chem. Int. Ed. Engl. 35 (1996) 414. (c) R. Dembinski, T. Bartik,
B. Bartik, M. Jaeger, J.A. Gladysz, manuscript in preparation.
[13] References to C8 complexes prepared in other laboratories: (a)
P.J. Kim, H. Masai, K. Sonogashira, N. Hagihara, Inorg. Nucl.
Chem. Lett. 6 (1970) 181. (b) F. Coat, C. Lapinte, Organometal-
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Skelton, A.H. White, Organometallics 17 (1998) 3539. (d) M.
Akita, M.-C. Chung, A. Sakurai, S. Sugimoto, M. Terada, M.
Tanaka, Y. Moro-oka, Organometallics 16 (1997) 4882.
[14] K. Sonogashira, in: F. Diederich, P.J. Stang (Eds.), Metal
Catalysed Cross-coupling Reactions, Wiley-VCH, Weinheim,
1998, p. 204.
Atomic co-ordinates and ORTEP diagrams for 7 and
8 have been deposited with the Cambridge Crystallo-
graphic Data Centre as supplementary publication no.
CCDC-103196 and 103197. Copies of the data can be
obtained free of charge on request to: The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(Fax: Int. code +(1223) 336-033; e-mail: de-
posit@chemcrys.cam.ac.uk). Structure factors and ther-
mal parameters have been deposited with the British
Library, Document Supply Centre at Boston Spa,
Wetherby, West Yorkshire, LS23, 7BQ, UK, as a sup-
plementary publication and are available on request
from the Document Supply Centre. Atomic co-ordi-
nates and equivalent isotropic thermal parameters of
hydrogens have been submitted to the Editor.
´
[15] (a) R.R. Kostikov, A.Ya. Krasikov, T.V. Mandel’shtam, E.M.
Kharicheva, Zh. Org. Khim. 21 (1985) 329. (b) V. Ratovelo-
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[16] Precedent for this methodology: H. Hofmeister, K. Annen, H.
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Chem. Int. Ed. Engl. 23 (1984) 727.
Acknowledgements
[17] W. Weng, T. Bartik, M. Brady, B. Bartik, J.A. Ramsden, A.M.
Arif, J.A. Gladysz, J. Am. Chem. Soc. 117 (1995) 11922.
[18] When the solvent is switched to methanol/THF (1:1 v/v), reac-
tion times are reduced by approximately half. This is likely due
to enhanced solubility.
The authors would like to thank the NSF for support
of this research.
[19] Aliquots of solutions of 4 and 6 were analyzed by IR (cm−1
,
THF): 4, wCꢀC 2025 m br (range over many experiments, 2010–
2028), wNO 1650 vs.; 6, wCꢀC 2079 vs., 2043 m, 1895 m, wNO 1655
vs.
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.