Alkyne oligomerization mediated by rhodium complexes with a phosphinosulfonamido ligand and isolation and characterization of a rhodacyclopentadiene complex

Article abstract of DOI:10.1016/j.jorganchem.2006.01.004

Treatment of N-tosyl aziridine with KPPh₂ in THF produces Ph₂PCH₂CH₂NTsK (Ts = p-CH₃C ₆H₄SO₂). Reaction of Ph₂PCH ₂CH₂NTsK with [Rh₂(μ₂-Cl) ₂(NBD)₂] (NBD = norbornadiene) and [Rh₂(μ ₂-Cl)₂(COD)₂] (COD = 1,5-cyclooctadiene) produces [Rh(NBD)(Ph₂PCH₂CH₂NTs)] and [Rh(COD)(Ph₂PCH₂CH₂NTs)] (4), respectively. Reaction of Ph₂PCH₂CH₂NTsK with [Ir ₂(μ₂-Cl)₂(COD)₂] gives [Ir(COD)(Ph₂PCH₂CH₂NTs)]. Complex 4 is catalytically active for polymerization of arylalkynes and for cyclotrimerization of HCCCOR (R = OEt, Me). The novel metallacycle [Rh(C(CO ₂Et)CHC(CO₂Et)CH)(CH(CO₂Et)CCCCO ₂Et)(Ph₂PCH₂CH₂NHTs)₂] was isolated from the reaction of 4 with ethyl propiolate. The metallacycle is catalytically active for cyclotrimerization of ethyl propiolate.

Full text of DOI:10.1016/j.jorganchem.2006.01.004

Journal of Organometallic Chemistry 691 (2006) 1945–1953
www.elsevier.com/locate/jorganchem
Alkyne oligomerization mediated by rhodium complexes
with a phosphinosulfonamido ligand and isolation and characterization
of a rhodacyclopentadiene complex
*
Peng Xue, Herman S.Y. Sung, Ian D. Williams, Guochen Jia
Department of Chemistry and Open Laboratory of Chirotechnology of the Institute of Molecular Technology for Drug Discovery and
Synthesis, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
Received 20 September 2005; received in revised form 13 December 2005; accepted 3 January 2006
Available online 23 February 2006
Abstract
Treatment of N-tosyl aziridine with KPPh2 in THF produces Ph2PCH2CH2NTsK (Ts = p-CH3C6H4SO2). Reaction of Ph2PCH2-
CH2NTsK with [Rh2(l2-Cl)2(NBD)2] (NBD = norbornadiene) and [Rh2(l2-Cl)2(COD)2] (COD = 1,5-cyclooctadiene) produces
[Rh(NBD)(Ph2PCH2CH2NTs)] and [Rh(COD)(Ph2PCH2CH2NTs)] (4), respectively. Reaction of Ph2PCH2CH2NTsK with [Ir2(l2-Cl)2-
(COD)2] gives [Ir(COD)(Ph2PCH2CH2NTs)]. Complex 4 is catalytically active for polymerization of arylalkynes and for cyclotrimeriza-
tion of HC„CCOR (R = OEt, Me). The novel metallacycle [Rh(C(CO2Et)@CHC(CO2Et)@CH)(CH(CO2Et)@CC„CCO2Et)-
(Ph2PCH2CH2NHTs)2] was isolated from the reaction of 4 with ethyl propiolate. The metallacycle is catalytically active for cyclotrimer-
ization of ethyl propiolate.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Metallacycles; Oligomerization; Alkynes; N,P ligands; Rhodium; Iridium
1. Introduction
metal complexes with hard/soft chelating ligands has
received much attention [3]. A number rhodium and irid-
ium complexes with other P,N mixed-donor ligands (for
example, phosphine-pyridine, phosphine-oxazoline, phos-
phine-pyrazolyl, and phosphine-imidazole) have been syn-
thesized and investigated for their catalytic properties [4].
In this work, we have synthesized and characterized
several new rhodium and iridium complexes with the
phosphinosulfonamido ligand [Ph2PCH2CH2NTs]ꢀ and
investigated their catalytic properties for cyclotrimerization
and polymerization of alkynes. During the course of the
work, we have isolated a rhodacyclopentadiene complex
from the reaction of [Rh(COD)(Ph2PCH2CH2NTs)] with
HC„CCO2Et. In rhodium mediated catalytic cyclotrimer-
ization reactions of alkynes [5], rhodacyclopentadienes
have often been proposed as the intermediates. Although
several rhodacyclopentadienes have been isolated from
the reactions of rhodium complexes with internal alkynes
[6], the isolation of rhodacyclopentadienes from the
Phosphines are among the most popular ligands in coor-
dination
chemistry
and
catalysis.
Sulfonamides
RSO2NHR0, which can be readily deprotonated to give sul-
fonamido anions [RSO2NR]ꢀ (much easier than deproto-
nation of RNHR0 to give [RNR0]ꢀ), have also attracted
much recent attention in coordination chemistry and catal-
ysis [1]. Thus it would be interesting to prepare metal com-
plexes from phosphinosulfonamide ligands and to test their
catalytic properties. However, well-characterized metal
complexes prepared from phosphinosulfonamide ligands
are very rare, although a few reports have appeared in
the literature on the catalytic reactions mediated by Pd
and Cu complexes with these ligands in the past few years
[2]. It should be noted that the chemistry of late transition
*
Corresponding author. Fax: +852 2358 1594.
E-mail address: chjiag@ust.hk (G. Jia).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.01.004

1946
P. Xue et al. / Journal of Organometallic Chemistry 691 (2006) 1945–1953
reactions of rhodium complexes with terminal alkynes is
rare [7].
2. Results and discussion
2.1. Preparation of [M(diene)(Ph2PCH2CH2NTs)]
complexes
Treatment of N-tosyl aziridine (1) [8] with KPPh2 in
THF produced the phosphinosulfonamido ligand Ph2-
PCH2CH2NTsK (2), which can be isolated as a white solid
in 76% yield (Scheme 1). The compound has been charac-
terized by NMR spectroscopy. In particular, the 31P{1H}
NMR spectrum in CDCl3 showed a singlet at ꢀ21.5 ppm.
The 1H NMR spectrum in CDCl3 showed the PCH2
and NCH2 signals at 2.79 and 2.04 ppm, in addition to
the characteristic signals of Ts and PPh2. Treatment of
Ph2PCH2CH2NTsK with [Rh2(l2-Cl)2(NBD)2] and
[Rh2(l2-Cl)2(COD)2] produced [Rh(NBD)(Ph2PCH2-
CH2NTs)] (3) and [Rh(COD)(Ph2PCH2CH2NTs)] (4),
respectively. Similarly, reaction of Ph2PCH2CH2NTsK
with [Ir2(l2-Cl)2(COD)2] gave [Ir(COD)(Ph2PCH2CH2-
NTs)] (5). Reported complexes closely related to complexes
3–5 include amido complexes [Ir(COD)(Ph2PCH2C-
Me2NH)] [9], [Rh(COD)(2-pyridinecarboxamido)] [10],
[M(CO)(PPh3)(Ph2PC6H4NH)] (M = Rh, Ir) [11] and
[Cp*RhCl(N-tolyl-1,2-cyclohexanediamine)] [12].
˚
Fig. 1. The molecular structure of 4. Selected bond distances (A) and
angles (ꢁ): Rh(1)–N(1), 2.1310(8); Rh(1)–P(1), 2.2606(6); Rh(1)–C(3),
2.229(2); Rh(1)–C(4), 2.264(2); Rh(1)–C(7), 2.117(2); Rh(1)–C(8),
2.138(2); P(1)–Rh(1)–N(1), 80.85(5).
2.2. Catalytic polymerization and cyclotrimerization
reactions
Rhodium(I) complexes can initiate oligomerization or
polymerization of alkynes depending on the ligand environ-
ments around rhodium, the structures of alkynes and the
reaction conditions. Many Rh(diene) complexes, for exam-
ple, [TpRh(COD)], [Rh2(l2-Cl)2(diene)2]/amine (diene =
COD, NBD), [Rh(COD)2]BF4, [Rh(NBD)(g6-C6H5BPh3)],
[Rh(C„CPh)(NBD)(PPh3)2], [RhClL(COD)] (L = neutral
phosphine or nitrogen donors), [Rh(diene)(N–N)]+ (N–N
= bidentate nitrogen donors) can catalyse alkyne
polymerization [13]. Rhodium complexes such as
[Rh(COD)(binap)]+ (binap = 2,20-bis(diphenylphosphino)-
1,10-binaphthyl), [Rh2(l2-Cl)2(COD)2]/TPPTS (TPPTS =
tris(3-sulfonatophenyl)phosphine) and [RhCl(PPh3)3] can
promote catalytic cyclotrimerization of alkynes [5]. In this
work, we have studied the reactivity of complexes 4 and
[Rh(NBD)(Ph2PCH2CH2NTs)] towards terminal alkynes,
in order to see how the phosphinosulfonamido ligand
[Ph2PCH2CH2NTs]ꢀ might influence the reactivity or cata-
lytic activity of the rhodium center.
The structures of the new complexes can be readily
assigned on the basis of their NMR and analytical data
(see Section 3). In addition, the structure of 4 has also been
confirmed by an X-ray diffraction study. The molecular
structure of 4 is shown in Fig. 1. The crystallographic
details and selected bond distances and angles are given
in Tables 1 and 2, respectively. The X-ray diffraction study
confirms that the phosphinosulfonamido ligand is chelated
to the rhodium center. The Rh–N bond distance
˚
(2.1310(18) A) is similar to that in [Cp*RhCl(N-tolyl-1,2-
˚
cyclohexanediamine)] (2.152(7) A) [12] and is slightly
longer than that of [Rh(COD)(2-pyridinecarboxamido)]
˚
(2.007(4) A) [10]. The C–C and C@C bond distances of
the COD ligand and the Rh–C(olefin) distances are normal
compared to those of the related Rh(COD) complex
[Rh(COD)(2-pyridinecarboxamido)] [10].
Complex 4 was found to be catalytically active for poly-
merization of arylalkynes (Eq. (1)). As shown in Table 4,
phenylacetylene is polymerized in organic solvents such as
CDCl3, CH2Cl2, benzene and THF (entries 1–5) to give
polymers with molecular weights (Mw) in the range of
17800–63200 and polydispersities in the range of 1.55–
2.88. The yields of the polymerization reactions carried
out in THF are better than those in CDCl3, CH2Cl2 or
benzene, although the origin of the difference is not clear
to us. For comparison, the molecular weight (Mw) and
polydispersity of poly(phenylacetylene) obtained with
[TpPh,MeRh(COD)] in CH2Cl2 are 47000 and 2.38,
Ph2
P
Ts
N
KPPh2
Rh2Cl2(NBD)2
Ir2Cl2(COD)2
Rh
NK
Ts
Ph2P
N
Ts
2
1
3
Rh2Cl2(COD)2
Ph2
P
Ph2
P
Rh
Ir
N
N
Ts
Ts
5
4
Scheme 1.

P. Xue et al. / Journal of Organometallic Chemistry 691 (2006) 1945–1953
1947
Table 1
for the polymerization of p-tolylacetylene (entry 6) to give
poly(p-tolylacetylene) with a similar structure. As indicated
by an in situ NMR experiment, complex 3 is also catalyti-
cally active for polymerization of phenylacetylene, giving
poly(phenylacetylene) with properties similar to those
obtained with complex 4. It is known that rhodium complex
[Rh(C„CPh)(NBD)(PPh3)2] can polymerize phenylacety-
lene to give living polymer, which can initiate further poly-
merization of alkynes [6c]. In our case, the isolated
polymers do not appear to have active rhodium centers,
as they do not react with additional phenylacetylene or
p-tolylacetylene in THF.
Crystal data and structure refinement for 4 and 8
Compound
4
8
Formula
C29H33NO2PRhS
593.50
Monoclinic
P21/n
13.4721(7)
13.2768(7)
15.7838(9)
113.3660(10)
2591.7(2)
4
C62H67N2O12P2RhS2
1261.15
Monoclinic
I2/a
30.166(3)
11.2074(11)
37.312(4)
109.793(2)
11869(2)
8
Formula weight
Crystal system
Space group
˚
a (A)
˚
b (A)
˚
c (A)
b (ꢁ)
Volume (A )
Z
Dcalcd (g/cm3)
Absorption
coefficient (mmꢀ1
h Range (ꢁ)
Index ranges
3
˚
1.521
0.829
1.411
0.476
Ar
Ar
4
)
Ar
1.69–26.00
ꢀ14 6 h 6 16,
ꢀ16 6 k 6 16,
ꢀ19 6 l 6 19
13611
1.43–25.00
ꢀ35 6 h 6 35,
ꢀ13 6 k 6 9,
ꢀ44 6 l 6 37
29409
ð1Þ
x
Ar
Ar
6a, R = Ph; 6b, R = p-tolyl
There are strong evidences that rhodium(I) mediated
polymerization of arylalkynes proceeds through insertion
of alkyne to Rh–vinyl bond [6c]. We assume that similar
mechanism is also involved in our system. Unfortunately,
our attempt to observe the reaction intermediates in the
reaction of complex 4 with HC„CPh failed. When the
reaction of complex 4 with HC„CPh in CD2Cl2 was mon-
itored by 31P NMR spectroscopy, only the 31P signals of
complex 4 and phosphine oxide can be observed.
Like many other Rh(I) complexes [13], complex 4 is cat-
alytically active for polymerization of arylalkynes, but has
very low catalytic activity, if any, for polymerization of ali-
phatic alkynes such as t-BuC„CH and n-BuC„CH. Inter-
estingly, when activating alkynes such as HC„CCO2Et
and HC„CCOMe were used as the substrates, they were
mainly converted to the cyclotrimers 1,3,5- and 1,2,4-
C6H3(COR)3 (7, R = OEt; 70, R = Me) in a ratio of ca.
1.1 rather than polymers (Eq. (2)). Cyclotrimerization of
HC„CCO2Et in benzene occurred at room temperature
in the presence of 3.3 mol% or 0.40 mol% of complex 4.
The Rh/substrate ratio, although affects the reaction rate,
has negligible effect on the distribution of the two isomeric
products. We have also carried out competitive reaction
between HC„CCO2Et and PhC„CH. In the presence of
1 mol% complex 4, a 1:1 mixture of HC„CCO2Et and
PhC„CH is converted to a complicated mixture, as indi-
cated by in situ 1H NMR. The mass spectrum of the
organic product obtained after purification by column
chromatography showed ion peaks corresponding to
Number of
reflections collected
Number of independent
reflections [Rint
Maximum and minimum
transmission
Number of data/
restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
5023 [0.0309]
1.00 and 0.82
5023/0/316
10398 [0.1140]
1.00 and 0.69
10398/0/732
]
1.018
1.002
R1 = 0.0298,
wR2 = 0.0721
0.768 and ꢀ0.594
R1 = 0.0576,
wR2 = 0.0969
1.581 and ꢀ0.908
Largest difference
peak and hole (e A
ꢀ3
˚
)
Table 2
Selected bond lengths (A) and angles (ꢁ) for 4
˚
Rh(1)–N(1)
Rh(1)–C(3)
Rh(1)–C(7)
C(3)–C(4)
2.1310(18)
2.229(2)
2.117(2)
1.366(3)
Rh(1)–P(1)
Rh(1)–C(4)
Rh(1)–C(8)
C(7)–C(8)
2.2605(6)
2.264(2)
2.138(2)
1.405(3)
N(1)–Rh(1)–P(1)
C(3)–Rh(1)–C(4)
C(7)–Rh(1)–C(4)
C(3)–Rh(1)–P(1)
C(7)–Rh(1)–P(1)
C(7)–Rh(1)–N(1)
N(1)–Rh(1)–C(3)
C(8)–Rh(1)–C(4)
C(10)–P(1)–Rh(1)
C(3)–C(4)–Rh(1)
C(8)–C(7)–Rh(1)
C(1)–C(8)–Rh(1)
C(2)–C(3)–Rh(1)
C(11)–P(1)–Rh(1)
80.85(5)
35.38(8)
80.35(9)
156.15(6)
94.19(6)
159.73(8)
95.30(7)
C(8)–Rh(1)–P(1)
C(7)–Rh(1)–C(8)
C(8)–Rh(1)–C(3)
P(1)–Rh(1)–C(4)
N(1)–Rh(1)–C(8)
N(1)–Rh(1)–C(4)
C(7)–Rh(1)–C(3)
C(9)–N(1)–Rh(1)
S(1)–N(1)–Rh(1)
C(4)–C(3)–Rh(1)
C(7)–C(8)–Rh(1)
C(6)–C(7)–Rh(1)
C(5)–C(4)–Rh(1)
C(17)–P(1)–Rh(1)
95.52(6)
38.57(9)
80.41(8)
168.47(6)
160.91(8)
100.77(8)
96.83(9)
119.28(14)
124.52(10)
73.70(13)
69.87(12)
110.10(15)
110.73(15)
115.66(7)
86.55(8)
100.47(8)
70.92(13)
71.55(12)
114.08(15)
107.34(14)
124.05(7)
C6H3(CO2Et)3
(3HC„CCO2Et),
C6H3(Ph)(CO2Et)2-
(HC„CPh + 2HC„CCO2Et), and C6H3(Ph)2(CO2Et)-
(2HC„CPh + HC„CCO2Et), suggesting that cyclotri-
merization of HC„CCO2Et and co-cyclotrimerization of
HC„CPh and HC„CCO2Et occurred. In agreement with
respectively [13a]; and those with [Rh(C„CPh)(NBD)-
(PPh3)2] in THF are 9010 and 1.17, respectively [6c]. As
indicated by the 1H and 13C{1H} NMR spectroscopic data,
the poly(phenylacetylene) formed from the reaction mainly
has a cis-transoidal structure [13g]. Preferential formation
of cis-transoidal poly(phenylaceylene) is common with
Rh(I) catalysts [13]. Complex 4 is also catalytically active
1
the MS, the H NMR spectrum showed the characteristic
proton signals of 1,3,5- and 1,2,4-C6H3(CO2Et)3 along with
additional proton signals in the region 7.2–8.8 ppm.
Unfortunately, we have not been able to fully separate
and characterize by NMR the co-cyclotrimerized species
C6H3(Ph)(CO2Et)2 and C6H3(Ph)2(CO2Et).

1948
P. Xue et al. / Journal of Organometallic Chemistry 691 (2006) 1945–1953
R
O
R
O
R
C
C
C
O
O
4
C
R
+
ð2Þ
R
C
O
C
R
O
C O
R
b
a
7, R = OEt, 7', R = Me
In contrast, the iridium complex 5 did not initiate either
polymerization or oligomerization of phenylacetylene and
ethyl propiolate under similar conditions. It should be
noted that alkyne polymerization or cyclotrimerization
mediated by iridium complexes is known. For example,
complexes such as [HIr(COD)(PR3)2], [Ir2(l2-X)2(COD)2]
(X = Cl, OMe) and Ir2(l2-Cl)2(COD)2/Ph2C = CPhLi can
catalyze the polymerization of phenylacetylene [14]; com-
plexes such as [HIr(COD)(dppe)] and [Ir2(l2-Cl)2(COD)2]/
P(C6F5)2CH2CH2P(C6F5)2 can catalyze the cyclotrimeriza-
tion of alkynes [15].
2.3. Isolation of the metallacycle 8
We have tried to detect the reaction intermediates in the
reaction of complex 4 with HC„CCO2Et. When the reac-
tion of complex 4 with HC„CCO2Et in CD2Cl2 was mon-
itored by 31P NMR spectroscopy, it was observed that the
31P signals of complex 4 gradually disappeared, and a dou-
blet at 17.4 ppm gradually appeared as the major new 31P
signals. The relative amount of HC„CCO2Et do not
appear to have much effect on the course of the reaction,
but a larger excess of HC„CCO2Et can speed up the con-
sumption of complex 4 and the formation of 8. The new
major species can be isolated as a yellow solid and was
identified to be the metallacycle [Rh(C(CO2Et)@CHC
(CO2Et)@CH)(CH(CO2Et)@CC„CCO2Et)(Ph2PCH2-
CH2NHTs)2] (8) (Eq. (3)). The other minor phosphorus-
containing species produced from the reaction, however,
are difficult to be isolated and characterized.
˚
Fig. 2. The molecular structure of 8. Selected bond distances (A) and
angles (ꢁ): Rh(1)–P(1), 2.3218(14); Rh(1)–P(2), 2.3243(14); Rh(1)–C(63),
2.089(5); Rh(1)–O(11), 2.223(3); Rh(1)–C(74), 2.098(5); Rh(1)–C(80),
1.972(4); O(11)–C(61), 1.246(5); C(61)–C(62),1.444(6); C(62)–C(63),
1.350(6); C(72)–C(80), 1.358(7); C(72)–C(73), 1.455(6); C(73)–C(74),
1.359(6); P(1)–Rh(1)–P(2), 174.53(5); C(63)–Rh(1)–O(11), 75.95(15);
C(74)–Rh(1)–C(80), 79.18(19).
Table 3
˚
Selected bond lengths (A) and angles (ꢁ) for 8
Rh(1)–C(80)
Rh(1)–C(63)
Rh(1)–P(1)
1.972(4)
2.089(5)
2.3218(14) Rh(1)–P(2)
Rh(1)–C(74)
Rh(1)–O(11)
2.098(5)
2.223(3)
2.3243(14)
1.350(6)
1.455(6)
1.246(5)
1.203(6)
C(61)–C(62)
C(72)–C(80)
C(73)–C(74)
O(21)–C(75)
1.444(6)
1.358(7)
1.359(6)
1.229(5)
C(62)–C(63)
C(72)–C(73)
O(11)–C(61)
O(24)–C(71)
TsHN
EtO2C
CO2Et
PPh2
Rh
EtO
C(80)–Rh(1)–C(63)
C(80)–Rh(1)–O(11) 174.46(17)
98.8(2)
C(80)–Rh(1)–C(74)
C(80)–Rh(1)–P(1)
79.18(19)
84.23(14)
C(63)–Rh(1)–C(74) 177.41(19)
C(63)–Rh(1)–P(1) 91.94(13)
C(74)–Rh(1)–O(11) 106.09(15)
85.91(13)
90.17(9)
C(61)–O(11)–Rh(1) 111.8(3)
C(27)–P(2)–Rh(1) 114.31(16)
O
+
Ph2
P
ð3Þ
C(80)–Rh(1)–P(2)
C(63)–Rh(1)–O(11)
C(63)–Rh(1)–P(2)
C(74)–Rh(1)–P(1)
O(11)–Rh(1)–P(1)
P(1)–Rh(1)–P(2)
C(7)–P(1)–Rh(1)
91.96(14)
75.95(15)
92.52(13)
89.52(13)
93.99(9)
Ph2P
Rh
CO2Et
N
NHTs
Ts
C(74)–Rh(1)–P(2)
O(11)–Rh(1)–P(2)
CO2Et
4
8
174.53(5)
117.66(16)
The structure of the metallacycle has been confirmed by
X-ray diffraction. The molecular structure is shown in
Fig. 2 and selected bond distances and angles are given in
Table 3. The crystal structure reveals that four molecules
of HC„CCO2Et have been incorporated into the rhodium
center: two of them are joined together with the metal cen-
ter to form a metallacyclopentadiene ring, and the other
two coupled to form a CH(CO2Et)@CC„CCO2Et ligand
which is also chelated to rhodium. The coordination geom-
etry around rhodium can be described as a distorted octa-
hedron with the PPh2 groups trans to each other. The
rhodacyclopentadiene ring is nearly planar with mean
C(62)–C(63)–Rh(1) 116.3(3)
C(75)–C(74)–Rh(1) 126.9(3)
C(73)–C(74)–Rh(1) 112.9(3)
C(64)–C(63)–Rh(1) 121.3(3)
C(72)–C(80)–Rh(1) 118.2(4)
C(62)–C(63)–C(64)
C(65)–C(64)–C(63)
C(80)–C(72)–C(73)
C(73)–C(72)–C(71)
C(73)–C(74)–C(75)
122.2(5)
171.6(5)
113.9(4)
122.1(5)
120.1 (5)
C(63)–C(62)–C(61)
C(64)–C(65)–C(66)
C(80)–C(72)–C(71)
C(74)–C(73)–C(72)
114.2(5)
173.2(5)
124.0(5)
115.8(5)
˚
plane deviation of 0.02 A. In the metallacycle, the C(80)–
C(72) (1.358(7) A) and C(73)–C(74) (1.359(6) A) bonds
are slightly shorter than that of C(72)–C(73) (1.455(6) A),
˚
˚
˚

P. Xue et al. / Journal of Organometallic Chemistry 691 (2006) 1945–1953
1949
as one might expect for a metallacyclopentadiene ring. The
structural features of the five-membered metallacyle are
similar to other structurally characterized rhodacyclopent-
adienes. The bond distances associated with the Rh(g2-
C(C„CCO2Et)@CHCO2Et) are comparable to those
reported for the related complexes [(g5:g1-(3-NIM)Ind-
P)Rh(g2-CPh@CMeCMe@O)] ((3-NIM)Ind-P, a phospho-
rus-containing indenyl ligand) [16] and [Cp*RhCl-
(l-SPr)(l-S(i-Pr)C@CHCO2Me)RhCp*]OTf [17]. The
solid-state structure is supported by the NMR spectro-
scopic data. In particular, the 31P{1H} NMR spectrum in
C6D6 showed a doublet at 17.4 ppm (J(RhP) = 110.6 Hz).
Complex 8 was found to initiate the cyclotrimerization of
HC„CCO2Et. Thus, when benzene solution of
a
HC„CCO2Et containing 8 (8 mol%) was heated at
50 ꢁC, ca. 64% of HC„CCO2Et was converted cleanly to
a mixture of 7a and 7b in a ratio of 1:1. However, no reac-
tion was observed when 8 is mixed with PhC„CH even
under refluxing conditions. When the reaction of 8 with
HC„CCO2Et or HC„CPh was monitored by 31P{1H}
NMR, only the 31P signal of 8 can been seen.
3. Experimental
1
The H NMR spectrum in C6D6 showed four sets of OEt
All manipulations were carried out under a nitrogen
atmosphere using standard Schlenk techniques unless other-
wise stated. Solvents were distilled under nitrogen from
sodium benzophenone (hexane, ether, THF), sodium (ben-
zene), or calcium hydride (CH2Cl2). The starting materials
tosyl aziridine [8], [Rh2(l2-Cl)2(COD)2] [20], [Rh2(l2-Cl)2-
(NBD)2] [21] and [Ir2(l2-Cl)2(COD)2] [22] were prepared
according to the literature methods. All other reagents were
used as purchased from Aldrich Chemical Co., USA.
proton signals, the RhCH signal at 9.67 ppm, the
CH(CO2Et) signal at 6.60 ppm, and the CH@C(Rh)CO2Et
signal at 8.35 ppm. A good 13C{1H} NMR spectrum could
not be obtained due to its poor solubility in common
organic solvents.
One may ask how complex 8 was formed. The fact that
the starting material 4 has only one phosphine ligand and
that complex 8 contains two phosphine ligands suggests
that formation of 8 is not a simple process and that there
must be other species generated along with 8. Unfortu-
nately, we have not been able to identify any complexes
except 8 from the reaction. Thus the detailed mechanism
for the formation of 8 cannot be defined. Intuitively, the
Microanalyses were performed by M-H-W Laboratories
1
(Phoenix, AZ). H, 13C{1H} and 31P{1H} NMR spectra
were collected on a Bruker ARX-300 spectrometer
1
(300 MHz). H and 13C NMR shifts are relative to TMS,
and 31P chemical shifts relative to 85% H3PO4. The molec-
ular weights and molecular weight distribution (Mw/Mn) of
polymers were measured by a Waters Associates 510 GPC
using THF as the eluent and were calibrated with polysty-
rene standards.
rhodacyclopentadiene
fragment
Rh(C(CO2Et)@CH–
C(CO2Et)@CH) can be formed by oxidative coupling of
two molecules of HC„CCO2Et on rhodium, and the vinyl
fragment Rh(C(C„CCO2Et)@CHCO2Et) could be formed
by coupling the acetylide and vinylidene ligands of an inter-
mediate containing Rh(C„CCO2Et)(@C@CHCO2Et).
Reactions of Rh(I) complexes with terminal alkynes to give
vinylidene complexes are well known [18]. Intramolecular
coupling reactions between acetylide and vinylidene ligands
on rhodium have also been demonstrated [19].
Complex 8 represents a rare example of rhodacyclo-
pentadiene formed from oxidative coupling of two
molecules of a terminal alkyne on rhodium. Rhodacyclo-
pentadienes are interesting because they have often been
proposed as the intermediates for cyclotrimerization of
alkynes mediated by rhodium complexes. Until now, only
a few of such complexes have been isolated from the reac-
tions of alkynes with rhodium complexes [6,7], although
there are many reported examples of alkyne cyclotrimer-
ization using Rh complexes as the catalysts [5]. Most of
the reported rhodacyclopentadienes are generated from
coupling of internal alkynes [6]. A previous example of
rhodacyclopentadiene formed from coupling of terminal
alkyne on rhodium is reported by Bianchini et al. from
the reaction of [RhCl(C2H4)CH3(C(CH2PPh2)3)] with
HC„CH [7].
3.1. Ph2PCH2CH2NTsK (2)
To a THF solution of KPPh2 (12.0 mL, 0.5 M,
6.00 mmol) was added dropwise a solution of tosyl aziri-
dine (1.13 g, 5.75 mmol) in THF (40 mL) at 0 ꢁC (the addi-
tion was completed in 1 h). The reaction mixture was then
allowed to warm up to r.t. and stirred overnight. The mix-
ture was filtered and the filtrate was concentrated to dry-
ness under vacuum. The residue was washed with diethyl
ether (20 mL · 3) and hexane (10 mL) and dried under vac-
uum to give a white solid. The solid was extracted with
MeOH (30 mL) and then filtered to give a clear colorless
solution. The MeOH was removed under vacuum to give
a white solid, which was collected by filtration, washed
with ether, and dried under vacuum. Yield: 1.84 g, 76%.
31P {1H} NMR (121.5 MHz, CDCl3, 298 K): d ꢀ21.5 (s).
1H NMR (300 MHz, CDCl3, 298 K):
d
2.04 (t,
JH,H = 7.2 Hz, 2H, CH2N), 2.21 (s, 3H, CH3), 2.79 (dt,
JP,H = 10.1 Hz, JH,H = 7.2 Hz, 2H, CH2P), 6.85 (d,
JH,H = 8.1 Hz, 2H, Ph of Ts), 7.10–7.21 (m, 10H, PPh2),
7.49 (d, JH,H = 8.1 Hz, 2H, Ph of Ts).
2.4. Catalytic activity of complex 8
3.2. [Rh(COD)(Ph2PCH2CH2NTs)] (4)
We have also tested the catalytic activity of the metalla-
To a stirred solution of [Rh2(l2-Cl)2(COD)2] (0.208 g,
cycle 8 for polymerization and trimerization of alkynes.
0.422 mmol) in THF (30 mL) was added a solution of

1950
P. Xue et al. / Journal of Organometallic Chemistry 691 (2006) 1945–1953
PPh2CH2CH2NTsK (0.355 g, 0.842 mmol) in THF
(30 mL) at 0 ꢁC. After the addition was completed, the
resulting mixture was stirred for further 30 min at 0 ꢁC,
and then warmed up to room temperature. The reaction
mixture was filtered, and the filtrate was concentrated to
dryness under vacuum. The residue was washed with
diethyl ether (5 mL · 3) to give a yellow powder. The ana-
lytically pure sample of 4 was obtained by column chroma-
tography on alumina with MeOH–THF (1:2, v/v) as the
eluent. Yield: 0.343 g, 69%. IR (KBr pellet, cmꢀ1):
C6H4), 128.7 (d, JP,C = 9.9 Hz, o- or m-PPh2), 128.9 (s,
C6H4), 130.2 (d, JP,C = 2.0 Hz, p-PPh2), 130.6, 131.2 (dd,
JP,C = 41.6 Hz, JRh,C = 3.1 Hz, ipso-PPh2), 132.6 (d,
JP,C = 11.5 Hz, o- or m-PPh2), 139.6 (s, C of C6H4),
143.9 (s, C of C6H4). Anal. Calc. for C28H29NO2PRhS
(577.48): C, 58.24; H, 5.06; N, 2.43. Found: C, 57.99; H,
5.16; N, 2.38%.
3.4. [Ir(COD)(Ph2PCH2CH2NTs)] (5)
m
asym(SO2) 1279,
m
sym(SO2) 1138. 31P {1H} NMR
To a stirred solution of [Ir2(l2-Cl)2(COD)2] (0.205 g,
0.305 mmol) in THF (10 mL) was added a solution of
PPh2CH2CH2NTsK (0.258 g, 0.612 mmol) in THF
(15 mL) at 0 ꢁC. After the addition was completed, the
resulting mixture was stirred for further 60 min at 0 ꢁC,
and then warmed up to room temperature. The reaction
mixture was filtered, the filtrate was concentrated under
vacuum to give a red oil, to which was added ether
(5 mL) to produce a yellowish orange solid. The solid
was collected by filtration, washed with diethyl ether
(5 mL · 2) to give a yellow powder. An analytically pure
sample of 5 was obtained by column chromatography on
alumina with ether/THF (5:2.5–3, v/v) as the eluent. Yield:
0.308 g, 74%. IR (KBr pellet, cmꢀ1): masym(SO2) 1279,
(121.5 MHz, C6D6, 298 K): d 50.0 (d, JRh,P = 179.5 Hz).
1H NMR (300 MHz, C6D6, 298 K): d 1.99–2.15 (m, 6H,
CH2), 2.26 (s, 3H, CH3), 2.33–2.44 (m, 4H, CH2P, CH2),
3.29 (br s, 2H, @CH), 3.54 (dt, JP,H = 27.7 Hz,
JH,H = 6.1 Hz, 2H, CH2N), 7.17–7.27 (m, 10H, @CH, Ph
of Ts, PPh2), 7.57 (t, JH,H = 8.4 Hz, 4H, PPh2), 8.44 (d,
JH,H = 8.0 Hz, 2H, Ts). 13C {1H} NMR (75.5 MHz,
C6D6, 298 K): d 21.6 (s, CH3), 29.6 (s, CH2 of COD),
32.1 (d, JP,C = 27.0 Hz, PCH2), 33.5 (d, JP,C = 2.9 Hz,
CH2 of COD), 48.9 (d, JP,C = 5.4 Hz, CH2N), 67.8 (d,
JRh,C = 12.8 Hz, @CH), 110.0 (dd, JRh,C = 10.1 Hz,
JP,C = 6.4 Hz, @CH), 128.1 (s, C6H4), 129.3 (d,
JP,C = 9.7 Hz, o- or m-PPh2), 129.5 (s, C6H4), 131.1 (d,
JP,C = 2.2 Hz, p-PPh2), 132.0 (dd, JP,C = 41.8 Hz,
JRh,C = 5.3 Hz, ipso-PPh2), 133.7 (d, JP,C = 10.8 Hz, o- or
m-PPh2), 140.2 (s, C of C6H4), 144.1 (s, C of C6H4). Anal.
Calc. for C29H33NO2PRhS (593.52): C, 58.69; H, 5.60; N,
2.36. Found: C, 58.50; H, 5.52; N, 2.30%.
m
sym(SO2) 1138. 31P {1H} NMR (121.5 MHz, C6D6,
1
298 K): d 39.0 (s). H NMR (300 MHz, C6D6, 298 K): d
1.80–1.88 (m, 2H, CH2 of COD), 1.97–2.04 (m, 4H, CH2
of COD), 2.23 (s, 3H, CH3), 2.25–2.37 (m, 4H, CH2 of
COD and CH2P), 2.89 (br m, 2H, @CH), 3.66 (dt,
JP,H = 26.0, JH,H = 6.1 Hz, 2H, CH2N), 6.95 (br m, 2H,
@CH), 7.15 (d, JH,H = 7.8 Hz, 2H, Ph of Ts), 7.19–7.23
(m, 6H, PPh2), 7.57 (m, 4H, PPh2), 8.44 (d, JH,H = 7.8 Hz,
2H, Ph of Ts). 13C {1H} NMR (75.5 MHz, C6D6, 298 K): d
21.6 (s, CH3), 30.9 (s, CH2 of COD), 33.4 (d, JP,C = 3.7 Hz,
CH2of COD), 33.5 (d, JP,C = 31.5 Hz, PCH2), 50.7
3.3. [Rh(NBD)(Ph2PCH2CH2NTs)] (3)
To a stirred solution of [Rh2(l2-Cl)2(NBD)2] (0.053 g,
0.12 mmol) in THF (8 mL) was added a solution of
PPh2CH2CH2NTsK (0.097 g, 0.23 mmol) in THF (8 mL)
at 0 ꢁC. After the addition was completed, the resulting
mixture was stirred for further 40 min at 0 ꢁC, and then
warmed up to room temperature. The reaction mixture
was filtered, the filtrate was concentrated to dryness under
vacuum. The residue was extracted with benzene (5 mL).
The benzene was removed to give a yellow solid, which
was collected by filtration, washed with diethyl ether
(3 mL · 2) and dried under vacuum to give a yellow pow-
der. Yield: 0.080 g, 60%. IR (KBr pellet, cmꢀ1): masym(SO2)
1289, msym(SO2) 1141. 31P {1H} NMR (121.5 MHz, C6D6,
(s, @CH), 52.7 (d, JP,C = 4.2 Hz, NCH2), 99.3 (d, JP,C
=
12.2 Hz, @CH), 128.1 (s, C6H4), 129.2 (d, JP,C = 10.1 Hz,
o- or m-PPh2), 129.6 (s, C6H4), 130.8 (d, JP,C = 50.3 Hz,
ipso-PPh2), 131.3 (d, JP,C = 2.3 Hz, p-PPh2), 134.0 (d,
JP,C = 10.6 Hz, o- or m-PPh2), 140.8 (s, C of C6H4),
143.3 (s, C of C6H4). Anal. Calc. for C29H33IrNO2PS
(682.83): C, 51.01; H, 4.87; N, 2.05. Found: C, 51.15; H,
4.73; N, 2.03%.
3.5. Cyclotrimerization of ethyl propiolate and isolation of
[Rh(C(CO2Et)@CHC(CO2Et)@CH)(CH(CO2Et)@
CCBCCO2Et)(Ph2PCH2CH2NHTs)] (8)
1
298 K): d 50.0 (d, JRh,P = 180.3 Hz). H NMR (300 MHz,
C6D6, 298 K): d 1.48 (t, JH,H = 1.2 Hz, 2H, CH2 of
NBD), 2.04 (m, 2H, CH2P), 2.25 (s, 3H, CH3), 3.37 (br
m, 2H, bridge-head CH of NBD), 3.51 (dt, JP,H = 26.7 Hz,
JH,H = 6.0 Hz, 2H, CH2N), 3.64 (br s, 2H, @CH), 6.59 (br
s, 2H, @CH), 7.19–7.28 (m, 8H, PPh2, Ph of Ts), 7.45–7.52
(m, 4H, PPh2), 8.46 (d, JH,H = 8.1 Hz, 2H, Ph of Ts). 13C
{1H} NMR (75.5 MHz, C6D6, 298 K): d 20.9 (s, CH3),
32.5 (d, JP,C = 26.8 Hz, CH2P), 48.0 (d, JP,C = 5.4 Hz,
CH2N), 49.4 (d, JRh,C = 10.9 Hz, CH of NBD), 51.0 (s,
@CH), 65.2 (d, JRh,C = 4.6 Hz, CH2 of NBD), 94.2 (dd,
JP,C = 4.9 Hz, JRh,C = 9.9 Hz, @CH of NBD), 127.5 (s,
A mixture of complex 4 (1.004 g, 1.629 mmol) and ethyl
propiolate (4.90 mL, 48.4 mmol) in dichloromethane
(35 mL) was stirred for 3.5 h. The volatile materials were
then removed under vacuum, the resulting residue was
extracted with benzene (20 mL, 5 mL · 2), and the com-
bined extracts were concentrated to dryness. Column chro-
matography on alumina (deactivated with 1% H2O, v/v)
with dichloromethane as the eluent gave a mixture of cyclo-
trimers 1,2,4- and 1,3,5-benzenetricarboxylic acid in a

P. Xue et al. / Journal of Organometallic Chemistry 691 (2006) 1945–1953
1951
molar ratio of 1.1:1. Yield: 1.95 g, 41% (based on ethyl pro-
piolate). Pure 1,3,5-isomer can be obtained as a white solid,
when the mixture was washed with acetone. 1H NMR
(300 MHz, CDCl3, 298 K) data of 1,2,4-C6H3(CO2Et)3: d
1.33 (t, JH,H = 7.2 Hz, 9H, CH3), 4.35 (q, JH,H = 7.2 Hz,
6H, OCH2), 7.73 (d, JH,H = 8.0 Hz, 1H, Ph), 8.16 (dd,
JH,H = 8.0 Hz, JH,H = 1.5 Hz, 1H, Ph), 8.37 (d,
JH,H = 1.5 Hz, 1H, Ph). 1H NMR (300 MHz, CDCl3,
(0.165 mL, 1.50 mmol) in THF (5 mL) was stirred at r.t.
for 20 h. The mixture was then concentrated under reduced
pressure. The product was purified by column chromatog-
raphy on silica eluting with dichloromethane to give a pasty
mixture of C6H3(COOEt)3, C6H3(C6H5)(COOEt)2, and
C6H3(C6H5)2(COOEt). Yield: 47 mg. MS (CI, m/z, %):
C6H3(C6H5)2(COOEt), exact mass, 302.13: 303 (M + 1,
3.7), 302 (M, 4.1); C6H3(C6H5)(COOEt)2, exact mass,
298.12: 299 (M + 1, 100), 298 (M, 71.0); C6H3(COOEt)3,
exact mass, 294.11: 295 (M + 1, 51.8), 294 (M, 9.4).
298 K) data of 1,3,5-C6H3(CO2Et)3:
d
1.43 (t,
JH,H = 7.1 Hz, 9H, CH3), 4.44 (q, JH,H = 7.1 Hz, 6H,
OCH2), 8.85 (s, 3H, Ph). Further eluting with THF gave
a red syrup after the solvent was evaporated, which was
chromatographed twice on silica with MeOH/dichloro-
methane (1:100, v/v) as the eluent to give complex 8 as a
red solid, which was purified by recrystallization from ben-
zene to give yellow crystals. Yield: 180 mg, 17% (based on
the rhodium complex). Characterization data of 8: 31P
{1H} NMR (121.5 MHz, C6D6, 298 K): d 17.4 (d,
3.8. Catalytic polymerization reactions
A typical procedure in preparative scale is described as
follows. To a solution of Rh(COD)(Ph2PCH2CH2NTs)
(17.8 mg, 0.030 mmol) in THF (1 mL) was added dropwise
a solution of phenylacetylene (0.165 mL, 1.50 mmol) in
THF (4 mL) at room temperature. After the mixture was
stirred for 2 h, the resulting mixture was diluted with
THF (5 mL), and then added to MeOH (150 mL) to give
a yellow precipitate, which was collected by filtration and
washed with acetone (10 mL · 3), dried under vacuum.
Yield: 0.11 g, 71%.
1
JRh,P = 110.6 Hz). H NMR (300 MHz, C6D6, 298 K): d
1.06 (t, JH,H = 7.1 Hz, 3H, CH3), 1.26 (t, JH,H = 7.1 Hz,
3H, CH3), 1.40 (t, JH,H = 7.1 Hz, 3H, CH3), 1.57 (t,
JH,H = 7.1 Hz, 3H, CH3), 2.14 (s, 6H, CH3), 2.8–3.0 (m,
8H, PCH2CH2N), 3.87 (q, JH,H = 7.1 Hz, 2H, OCH2),
4.24 (q, JH,H = 7.1 Hz, 2H, OCH2), 4.36 (q, JH,H = 7.1 Hz,
2H, OCH2), 4.69 (q, JH,H = 7.1 Hz, 2H, OCH2), 5.70 (br t,
2H, NH), 6.60 (br, 1H, @CH), 7.03 (d, JH,H = 8.1 Hz, 4H,
Ph of Ts), 7.17–7.24 (m, 4H, PPh2), 7.32–7.43 (m, 8H,
PPh2), 7.74 (m, 8H, PPh2), 7.85 (d, JH,H = 8.1 Hz, 4H,
Ph of Ts), 8.35 (br s, 1H, RhC(CO2Et)@CH), 9.67 (br,
1H, RhCH). Anal. Calc. for C62H67N2O12P2RhS2-
(1261.18): C, 59.04; H, 5.35; N, 2.22. Found: C, 59.31; H,
5.49; N, 2.25%.
A typical procedure in NMR tube experiment is
described as follows. A solution of complex 4 (5.4 mg,
9.1 lmol) and phenylacetylene (0.025 mL, 0.23 mmol) in
CDCl3 (0.40 mL) in a NMR tube was allowed to stand at
1
room temperature for 50 min. An in situ H NMR spec-
trum shows that the phenylacetylene was almost com-
pletely consumed. The product was precipitated out by
addition of diethyl ether (25 mL). The solid was washed
with methanol (2 mL), ether (5 mL) and dried under vac-
uum to give an orange-yellow powder. Yield: 9.1 mg,
39%. Similar results were obtained when [Rh(NBD)
(Ph2PCH2CH2NTs)] was used as the catalyst. The molecu-
lar weight and molecular weight distribution Mw/Mn are
given in Table 4.
3.6. Cyclotrimerization of HCBCCOMe
A mixture of complex 4 (8.9 mg, 0.015 mmol) and
HC„CCOMe (0.116 mL, 1.50 mmol) in THF (5 mL) was
stirred at r.t. for 20 h. The reaction mixture was concen-
trated under reduced pressure. The product was purified
by column chromatography on silica gel eluting with
dichloromethane and dichloromethane/acetone (20:3, v/v)
to give a pale yellow needles after removal of solvents.
The product is a mixture of 1,3,5-C6H3(COMe)3 and
1,2,4-C6H3(COMe)3 in a ratio of 1:1. Yield: 20 mg, 20%.
1H NMR of 1,3,5-C6H3(COMe)3 (300 MHz, CDCl3,
NMR data for poly(phenylacetylene): 1H NMR
(300 MHz, CDCl3, 298 K): d 5.85 (br s, 1H,@CH), 6.64
(br s, 2H, o-Ph), 6.95 (br, 3H, m, p-Ph). 13C {1H} NMR
(75.5 MHz, CDCl3, 298 K): d 126.8 (s, p-Ph), 127.7 (s, o-
or m-Ph), 127.9 (s, o- or m-Ph), 131.9 (s, @CH), 139.4 (s,
ipso-Ph), 143.0 (s, @CPh). The NMR data match those
reported in the literature [11 g]. NMR data for poly(p-tol-
ylacetylene): 1H NMR (300 MHz, CDCl3, 298 K): d 2.2 (br
s, 3H, CH3), 5.84 (br s, 1H, @CH), 6.34–6.66 (br s, 2H,
C6H4), 6.66–7.08 (br, 2H, C6H4). Further details on the
reaction conditions and polymer properties are given in
Table 4.
1
298 K): d 2.71 (s, 9H, CH3), 8.70 (s, 3H, Ph). H NMR
of 1,2,4-C6H3(COMe)3(300 MHz, CDCl3, 298 K): d 2.55
(s, 3H, CH3), 2.61 (s, 3H, CH3), 2.66 (s, 3H, CH3), 7.58
(d, J(HH) = 7.9 Hz, 1H, Ph), 8.11 (dd, J(HH) = 1.5 Hz,
7.9 Hz, 1H, Ph), 8.20 (d, J(HH) = 1.5 Hz, 1H, Ph). MS
(CI, exact mass, 204.08, m/z): 205 (M + 1).
3.9. Crystallographic analysis
3.7. Cyclotrimerization of HCBCCO2Et in the presence of
PhCBCH
Single crystals of 4 were obtained by layering hexane on
top of a solution of the complex in benzene. Single crystals
of 8 were obtained by slow evaporation of a solution of this
complex in CH2Cl2–diethylether (1:7). Selected yellow crys-
tals of 4 and 8, with crystal sizes of 0.20 · 0.15 · 0.10 mm3
A mixture of complex 4 (17.8 mg, 0.0300 mmol),
HC„CCO2Et (0.152 mL, 1.50 mmol) and PhC„CH

1952
P. Xue et al. / Journal of Organometallic Chemistry 691 (2006) 1945–1953
Table 4
Polymerization of ArC„CH catalyzed by [Rh(COD)(Ph2PCH2CH2NTs)]a
Timeb
Mw
Mw/Mn
Yield (%)d
c
c
Entry
Ar/[M] (mol/L)
[Cat] (mmol/L)
Solvent
1
2
3
4
5
6
a
Ph/0.56
Ph/1.5
Ph/1.5
Ph/1.5
Ph/0.30
p-Tolyl/0.30
23
15
15
15
6
CDCl3
C6H6
THF
CH2Cl2
THF
50 min
2 h
2 h
2 h
2 h
17800
28600e
63200
33300
48100
27100e
1.55
2.88
2.85
2.25
2.61
6.33
39
41
74
44
71
78
3
THF
2 h
All reactions were carried out at room temperature. Entry 1 was carried out in an NMR tube with 0.40 mL of CDCl3. The rest were carried in
preparative scale with ca. 5 mL of solvent.
b
The reaction time is not optimized.
Determined by GPC based on polystyrene standards.
Isolated yields.
c
d
e
Some polymer is insoluble in THF. Mw is referred to the portion soluble in THF.
and 0.20 · 0.20 · 0.15 mm3, respectively, were mounted on
(e) R. Noyori, S. Hashiguchi, Acc. Chem. Res. 30 (1997) 97;
(f) E. Royo, J.M. Betancort, T.J. Davis, P. Carroll, P.J. Walsh,
a glass fibre and transferred into the cold stream of nitro-
Organometallics 19 (2000) 4840;
gen. Data collections were performed on a Bruker Apex
(g) J.J. Becker, P.S. White, M.R. Gagne, Inorg. Chem. 38 (1999) 798;
CCD Area Detector by using graphite-monochromated
(h) S.W. Seidel, T.J. Deming, Macromolecules 36 (2003) 969.
˚
Mo Ka radiation (k = 0.71073 A) at 100(2) K. Multi-scan
[2] (a) I.J. Krauss, J.L. Leighton, Org. Lett. 5 (2003) 3201;
(b) M. Gustafsson, K.E. Bergqvist, T. Frejd, J. Chem. Soc., Perkin
Trans. 1 (2001) 1452;
absorption corrections (SADABS) [23] were applied. All
structures were solved by direct methods, expanded by
(c) M.J. Rachita, R.L. Huff, J.L. Bennett, M.J. Brookhart, J. Polym.
difference Fourier syntheses and refined by full matrix
Sci. (A) 38 (2000) 4627;
least-squares on F2 using Bruker SHELXTL (Version 5.10)
(d) K. Hiroi, A. Hidaka, R. Sezaki, Y. Imamura, Chem. Pharm.
program package [24]. All non-hydrogen atoms were
refined anisotropically. Further details on crystal data,
data collection and refinements are summarized in Table
1 and selected bond distances and angles are given in
Tables 2 and 3. Crystallographic data (excluding structure
factors) for the structures reported in this paper have been
deposited with the Cambridge.
Bull. 45 (1997) 769;
(e) S. Sakuraba, T. Okada, T. Morimoto, K. Achiwa, Chem. Pharm.
Bull. 43 (1995) 927;
(f) S. Sakuraba, K. Awano, K. Achiwa, Synlett (1994) 291;
(g) T. Okada, T. Morimoto, K. Achiwa, Chem. Lett. (1990) 999.
[3] (a) F. Speiser, P. Braunstein, L. Saussine, Acc. Chem. Res. 38 (2005)
784;
(b) P. Braunstein, J. Organomet. Chem. 689 (2004) 3953;
(c) P. Braunstein, F. Naud, Angew. Chem. Int. Ed. 40 (2001) 40680;
(d) G. Helmchen, A. Pfaltz, Acc. Chem. Res. 33 (2000) 33336.
[4] Examples of recent work: (a) S.I. Pascu, K.S. Coleman, A.R. Cowley,
M.L.H. Green, N.H. Rees, J. Organomet. Chem. 690 (2005) 1645,
and references therein;
4. Supplementary material
Crystallographic Data Center as Supplementary Publi-
cations Nos. CCDC-264868 (4) and CCDC-264869 (8).
Copies of the data can be obtained free of charge on appli-
cation to Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB21EZ, UK, fax: +44 1223
336 033; or email: deposit@ccdc.cam.ac.uk.
(b) M.A. Casado, V. Hack, J.A. Camerano, M.A. Cirian, C. Tejel,
L.A. Oro, Inorg. Chem. 44 (2005) 9122;
(c) W. Weng, C. Guo, C. Moura, L. Yang, B.M. Foxman, O.V.
Ozerov, Organometallics 24 (2005) 3847;
(d) S. Tanaka, C. Dubs, A. Inagaki, M. Akita, Organometallics 24
(2005) 163;
(e) S. Burling, L.D. Field, B.A. Messerle, K.Q. Vuong, P. Turner,
Dalton Trans. (2003) 4181;
(f) A. Aghmiz, A.M. Masdeu-Bulto, C. Claver, D. Sinou, J. Mol.
Catal. (A) 184 (2002) 111.
Acknowledgments
The authors acknowledge financial support from the
Hong Kong Research Grants Council and the University
Grants Committee of Hong Kong through the Area of
Excellence Scheme (AoE).
[5] Examples of recent work on rhodium catalyzed alkyne cyclotrimer-
ization: (a) P. Tagliatesta, B. Floris, P. Galloni, A. Leoni, G.
D’Arcangelo, Inorg. Chem. 42 (2003) 7701;
(b) K. Tanaka, K. Shirasaka, Org. Lett. 5 (2003) 4697;
(c) G.A. Ardizzoia, S. Brenna, S. Cenini, G. La Monica, N.
Masciocchi, A. Maspero, J. Mol. Catal. (A) 204 (2003) 333;
(d) W.S. Han, S.W. Lee, J. Organomet. Chem. 678 (2003) 10;
(e) H. Kinoshita, H. Shinokubo, K. Ohsima, J. Am. Chem. Soc. 125
(2003) 7784;
References
[1] Examples of recent work on coordination chemistry and catalysis
with sulfonamide ligands: (a) K.H. Wu, H.M. Gau, Organometallics
23 (2004) 580;
(f) B. Witulski, A. Zimmermann, N.D. Gowans, Chem. Commun.
(2002) 2984;
(b) K.H. Wu, H.M. Gau, Organometallics 22 (2003) 5193;
(c) M. Schleusner, H.J. Gais, S. Koep, G. Raabe, J. Am. Chem. Soc.
124 (2002) 7789;
(g) F.E. McDonald, V. Smolentsev, Org. Lett. 4 (2002) 745;
(h) M. Herberhold, H. Yan, W. Milius, B. Wrackmeyer, Organomet-
allics 19 (2000) 4289.
(d) K. Murata, H. Konishi, M. Ito, T. Ikariya, Organometallics 21
(2002) 253;
[6] (a) H. Nishiyama, E. Niwa, T. Inoue, Y. Ishima, K. Aoki,
Organometallics 21 (2002) 2572;

P. Xue et al. / Journal of Organometallic Chemistry 691 (2006) 1945–1953
1953
(b) J.R. Rourke, A.S. Batsanov, J.A.K. Howard, T.B. Marder,
Chem. Commun. (2001) 2626;
(c) V. Kishimoto, P. Eckerle, T. Miyatake, M. Kainosho, A. Ono, T.
Ikariya, R. Noyori, J. Am. Chem. Soc. 121 (1999) 12035;
(d) M. Iglesias, C. del Pino, J. Ros, S.G. Blanco, S.M. Carrera, J.
Organomet. Chem. 338 (1988) 89;
(e) R.G. Gastinger, M.D. Rausch, D.A. Sullivan, G.J. Palenik, J.
Organomet. Chem. 117 (1976) 335;
(f) J.T. Mague, Inorg. Chem. 12 (1973) 2649;
[14] Examples of recent work on iridium catalyzed alkyne polymerization:
(a) M. Marigo, D. Millos, N. Marsich, E. Farnetti, J. Mol. Catal. (A)
206 (2003) 319;
(b) M. Marigo, N. Marsich, E. Farnetti, J. Mol. Catal. (A) 187 (2002)
169;
(c) K. Kanki, Y. Misumi, T. Masuda, J. Polym. Sci. (A) 40 (2002) 1075.
[15] Examples of recent work on iridium catalyzed alkyne cyclotrimeriza-
tion: (a) E. Farnetti, N. Marsich, J. Organomet. Chem. 689 (2004) 14;
(b) R. Takeuchi, Y. Nakaya, Org. Lett. 5 (2003) 3659;
(c) R. Takeuchi, S. Tanaka, Y. Nakaya, Tetrahedron Lett. 42 (2001)
2991;
(d) C. Bianchini, K.G. Caulton, C. Chardon, M.L. Doublet, O.
Eisenstein, S.A. Jackson, T.J. Johnson, A. Meli, M. Peruzzini, W.E.
Streib, A. Vacca, F. Vizza, Organometallics 13 (1994) 2010.
[16] Y. Kataoka, Y. Iwato, A. Shibahara, T. Yamagata, K.K. Tani,
Chem. Commun. (2000) 841.
(g) J.T. Mague, Inorg. Chem. 9 (1970) 1610.
[7] (a) C. Bianchini, D. Masi, A. Meli, M. Peruzzini, A. Vacca, F.
Laschi, P. Zanello, Organometallics 10 (1991) 636;
(b) C. Bianchini, A. Meli, M. Peruzzini, A. Vacca, F. Vizza,
Organometallics 10 (1991) 645;
(c) C. Bianchini, K.G. Caulton, C. Chardon, K. Folting, T.J.
Johnson, A. Meli, M. Peruzzini, D.J. Rauscher, W.E. Streib, F.
Vizza, J. Am. Chem. Soc. 113 (1991) 5127.
[17] Y. Ishii, K.I. Ogio, M. Nishio, M. Retboll, S. Kuwata, H. Matsuzaka,
M. Hidai, J. Organomet. Chem. 599 (2000) 221.
[18] (a) P. Kruger, H. Werner, Eur. J. Ing. Chem. (2004) 481;
¨
[8] B.K. Wagnon, S.C. Jackels, Inorg. Chem. 28 (1989) 1923.
[9] (a) L. Dahlenburg, R. Go¨tz, Eur. J. Inorg. Chem. (2004) 888;
(b) L. Dahlenburg, R. Go¨tz, J. Organomet. Chem. 619 (2001) 88.
[10] H. Brunner, B. Nuber, M. Prommesberger, J. Organomet. Chem. 523
(1996) 179.
[11] (a) L. Dahlenburg, K. Herbst, Chem. Ber. 130 (1997) 1693;
(b) L. Dahlenburg, K. Herbst, J. Chem. Soc., Dalton Trans. (1999)
3935.
(b) J. Gil-Rubio, M. Laubender, H. Werner, Organometallics 19
(2000) 1365;
(c) R. Wiedemann, R. Fleischer, D. Stalke, H. Werner, Organomet-
allics 16 (1997) 866;
(d) Y. Wakatsuki, N. Koga, H. Werner, K. Morokuma, J. Am.
Chem. Soc. 119 (1997) 360;
[12] K. Murata, T. Ikariya, R. Noyori, J. Org. Chem. 64 (1999) 2186.
[13] Examples of recent work on rhodium catalyzed alkyne polymeriza-
tion: (a) T. Ruman, Z. Ciunik, A.M. Trzeciak, S. Wolowiec, J.J.
Ziolkowski, Organometallics 22 (2003) 1072;
(e) H. Werner, J. Organomet. Chem. 475 (1994) 45.
[19] (a) B. Callejas-Gaspar, M. Laubender, H. Werner, J. Organomet.
Chem. 684 (2003) 144;
(b) H. Werner, R. Wiedemann, P. Steinert, J. Wolf, Chem. Eur. J. 3
(1997) 127;
(c) R. Wiedemann, P. Steinert, M. Schafer, H. Werner, J. Am. Chem.
Soc. 115 (1993) 9864.
(b) K. Kanki, A. Nakazato, R. Nomura, F. Sanda, T. Masuda, J.
Polym. Sci. (A) 42 (2004) 2100;
(c) R. Nonokawa, M. Oobo, E. Yashima, Macromolecules 36 (2003)
6599;
(d) H. Goto, H.Q. Zhang, E. Yashima, J. Am. Chem. Soc. 125 (2003)
2516;
(e) J. Tabei, R. Nomura, T. Masuda, Macromolecules 36 (2003)
573;
[20] T.G. Schenck, J.M. Downes, C.R.C. Milnes, P.B. Mackenzie, H.
Boucher, J. Whelan, B. Bosnich, Inorg. Chem. 24 (1985) 2334.
[21] E.W. Abel, M.A. Bennett, G. Wilkinson, J. Chem. Soc. (A) (1959)
3178.
[22] J.L. Herde, J.C. Lambert, C.V. Senoff, Inorg. Synth. 15 (1974) 18.
[23] G.M. Sheldrick, SADABS, Empirical Absorption Correction Program,
University of Go¨ttingen, Germany, 1996.
(f) J.P. Claverie, R. Soula, Prog. Polym. Sci. 28 (2003) 619, and
references therein;
(g) J. Yao, W.T. Wong, G. Jia, J. Organomet. Chem. 598 (2000)
228, and references therein.
[24] Bruker, SHELXTLTM Reference Manual (Version 5.1), Bruker Analyt-
ical X-Ray Systems Inc., Madison, Wisconsin, USA, 1997.