Carbon-carbon bond formation between adjacent alkenyl ligands: η3-allyl iridium(III) and η4-butadiene iridium(I) complexes from a cis-bis(alkenyl) iridium(III) complex

Article abstract of DOI:10.1021/om030090r

A carbon-carbon bond is formed between the α-carbons of the alkenyl ligands of the cis-bis(ethenyl)iridium complex [Ir(-CH=CH₂)₂(CH₃CN)₂ (PPh₃)₂]⁺ (2) to produce the η³-allyl complex [Ir(η³-CH₃ CHCHCH₂)(NCCH₃)₂ (PPh₃)₂]²⁺ (4) in the reaction of 2 with H⁺, and η⁴-butadiene complexes Ir(η⁴-CH₂=CHCH=CH₂)(A) (PPh₃)₂ (A = -CH=CH-⁺NEt₃ (6), -C≡ CR (7)) in reactions of 2 with terminal alkynes (RC≡CH; R = H, Ph, and p-C₆H₄CH₃) in the presence of NEt₃. The deuterium labeling experiments suggest an initial attack of H⁺ on the β-carbon of an ethenyl ligand to lead to the C-C bond formation between the α-carbons of the two alkenyl groups of 2 to produce 4.

Full text of DOI:10.1021/om030090r

Organometallics 2003, 22, 2119-2123
2119
Ca r bon -Ca r bon Bon d F or m a tion betw een Ad ja cen t
Alk en yl Liga n d s: η3-Allyl Ir id iu m (III) a n d η4-Bu ta d ien e
Ir id iu m (I) Com p lexes fr om a cis-Bis(a lk en yl)
Ir id iu m (III) Com p lex
Chong Shik Chin,* Hyungeui Lee, Soyoung Noh, Hyeyun Park, and Mieock Kim
Chemistry Department, Sogang University, Seoul 121-742, Korea
Received February 7, 2003
A carbon-carbon bond is formed between the R-carbons of the alkenyl ligands of the cis-
bis(ethenyl)iridium complex [Ir(-CHdCH2)2(CH3CN)2(PPh3)2]+ (2) to produce the η3-allyl
complex [Ir(η3-CH3CHCHCH2)(NCCH3)2(PPh3)2]2+ (4) in the reaction of 2 with H+, and η4-
butadiene complexes Ir(η4-CH2dCHCHdCH2)(A)(PPh3)2 (A ) -CHdCH-+NEt3 (6), -Ct
CR (7)) in reactions of 2 with terminal alkynes (RCtCH; R ) H, Ph, and p-C6H4CH3) in the
presence of NEt3. The deuterium labeling experiments suggest an initial attack of H+ on
the â-carbon of an ethenyl ligand to lead to the C-C bond formation between the R-carbons
of the two alkenyl groups of 2 to produce 4.
Sch em e 1
In tr od u ction
Transition metal-mediated C-C bond formation be-
tween alkynes has been extensively investigated since
it is probably the most useful transformation in syn-
thetic chemistry.1 It is likely that metal-hydrocarbyls
such as metal-alkyls, -alkenyls, -alkynyls, -carbenes,
and -vinylidenes are the intermediates formed during
the C-C coupling.1,2
We have recently reported that some alkynyl-iridium
complexes are utilized as precursors for the C-C bond
formation to give polyenes such as di-, tri-, and tet-
raenes.2 Iridium-alkynyls (Ir-CRtCâ-R)2 are readily
protonated at the electrophilic â-carbon to give iridium-
vinylidenes (IrdCRdCâHR) that undergo carbon-carbon
coupling reactions with adjacent hydrocarbyl ligands (Ir-
alkyl,2a,d,e Ir-alkenyl,2a-c and Ir-allyl2a,f) to produce those
polyenes.
Resu lts a n d Discu ssion
Reaction of the cis-bis(ethenyl) Ir(III) complex [Ir(-
CHdCH2)2(CH3CN)2(PPh3)2]+ (2)2b,3 with H+ readily
gives the η3-allyl complex [Ir(η3-CH3CHCHCH2)(CH3-
CN)2(PPh3)2]2+ (4), which slowly undergoes reductive
deprotonation at room temperature to give the η4-
butadiene complex [Ir(η4-CH2dCHCHdCH2)(CH3CN)-
(PPh3)2]+ (5) (Scheme 1). Complex 5 is also obtained
directly by heating 2 in CHCl3 at 60 °C (Scheme 1). In
the presence of NEt3, complex 2 reacts with alkynes
HCtCH and RCtCH (R ) C6H5 and p-C6H4CH3) to give
the alkenyl η4-butadiene complex Ir(-CHdCH-+NEt3)-
(η4-CH2dCHCHdCH2)(PPh3)2 (6) and alkynyl η4-buta-
diene complexes Ir(-CtCR)(η4-CH2dCHCHdCH2)-
(PPh3)2 (7, R ) C6H5 (a ), p-C6H4CH3 (b)),2b respectively,
in high yields (Scheme 1). These 18-electron Ir(I)
complexes (5, 6, and 7) are very stable both in the solid
state and in solution at 25 °C even in air for several
We now wish to report a proton-initiated C-C bond
formation between cis-bis(alkenyl) ligands of iridium-
alkenyls (Ir-CHdCH2)2b,3 to produce 2-butene and 1,3-
butadiene via iridium-carbene (IrdCHCH3) intermedi-
ates.
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(3) Iridium-alkenyls, cis-bis(ethenyl) Ir(III) complexes [Ir(-CHd
CH2)2L′2(PPh3)2]+ (L′ ) CH3CN (2), CO (3)) have been prepared by the
insertion of HCtCH into Ir-H bonds of the cis-dihydrido Ir(III)
complex [Ir(H)2(NCCH3)2(PPh3)2]+ (1). See Experimental Section in ref
2b.
10.1021/om030090r CCC: $25.00 © 2003 American Chemical Society
Publication on Web 04/17/2003

2120 Organometallics, Vol. 22, No. 10, 2003
Chin et al.
Sch em e 2
hours. Complex 4 reacts with H2 to give 2-butene
(mixture of cis and trans), butane, and cis,cis-[Ir(H)2-
(NCCH3)2(PPh3)2]+ (1), while 1,3-butadiene is liberated
from 7 by reactions with CO, which affords Ir(CtCR)-
(CO)(PPh3)2.
There are a few examples of proton-initiated C-C
bond formation between adjacent alkenyl ligands to give
η3-allyl complexes4 and of reductive C-C coupling
between two cis-alkenyl ligands by thermal activation
to give η4-butadiene complexes.5 Hardly does the con-
version of η3-butenyl complex to η4-butadiene complex
occur under normal conditions except one by photolysis.6
Neither the C-C coupling reaction between cis-
ethenyl groups nor protonation has been observed for
the cis,cis-dicarbonylbis(ethenyl) complex [Ir(-CHd
CH2)2(CO)2(PPh3)2]+ (3)2b,3 to give an η4-butadiene or
η3-allyl complex. Instead, tris(alkenyl) Ir(III) complex
8 and alkynyl bis(alkenyl) Ir(III) complexes 92b are
obtained from reaction with alkynes in high yields (eq
1). Both 8 and 9 are stable both in the solid state and
in solution at 25 °C even in air for several hours.
Attempts to observe C-C bond formation between the
two cis-alkenyl ligands of 8 have been unsuccessful thus
far, while complexes 9 undergo proton-initiated C-C
coupling reaction between the alkynyl and two cis-
alkenyl ligands to produce cross-conjugated hexatrienes
(RCHdC(CHdCH2)2, R-HEX).2b
the 1,3-butadiene of Ir(η4-CH2dCHCHdCH2) at δ 72.1-
89.1 and those due to the outer carbons of Ir(η4-CH2d
CHCHdCH2) at δ 31.3-42.0. 31P NMR spectra of these
complexes show two signals at δ 5.6-15.3 and δ -7.1
to -8.0, respectively (see Experimental Section), as does
the related η4-1,3-butadiene complex (PPh3)2ClRh(η4-
CH2dCHC(Ph)dCH2),9 whose crystal structure shows
the two PPh3 being nonequivalent.
To obtain more information on the reaction pathway
for the proton-initiated C-C coupling reaction between
the two cis-ethenyl ligands (2 f 4), deuterium labeling
experiments (see eq 2 and Scheme 2) have been carried
out. The d1 isotopomer [Ir(η3-CH2DCHCHCH2)(NCCH3)2-
(PPh3)2]2+ (4-d 1) is obtained from the reaction of 2 with
D+ and found to react with NR′3 (NC5H5 (a ), NEt3 (b))
to produce trans-2-butenylammonium cations trans-
CH2DCHdCHCH2N+R′3 (10-d 1) (eq 2). This nucleophilic
attack of NR′3 on the terminal CR carbon of the η3-
butenyl (η3-CH3CγHCâHCRH2) group of 4 is somewhat
expected since allylic ligands are known to be readily
attacked by nucleophiles to form C-C and C-hetero-
atom bonds.7 Isolated metal complexes ([Ir] in eq 2) from
the reactions of 2 with D+ have not been fully charac-
terized.
Newly prepared compounds 4, 5, 6, and 8 have been
unambiguously identified by detailed spectral (1H, 13C,
1
1
1H, H-2D COSY, H, 13C-2D HETCOR, and 31P NMR)
and elemental analysis data (see Experimental Section).
Characterization of 4 is rather straightforward by
comparing the spectral data with those for related allylic
metal compounds.4,7 The 13C NMR spectrum of 4 shows
all four carbons for the allyl ligand at 16.4-116.6 ppm
(see Experimental Section).
Assignments of 1H NMR signals to Ir-CHRdCHâ-
+NR3 (R ) Et (6), Me (8)) are also straightforward by
comparing the data with those for the related well-
characterized complexes containing Ir-CHdCH-+NR3
and other related metal alkenyls.2e,8 13C NMR spectra
of 5 and 6 show the signals due to the inner carbons of
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Organometallics 1997, 16, 2919.
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C-C Bonds between Adjacent Alkenyl Ligands
Organometallics, Vol. 22, No. 10, 2003 2121
Sch em e 3
â-carbon of an ethenyl group and (ii) reductive C-C
coupling to produce η4-1,3-butadiene complexes.
Exp er im en ta l Section
Gen er a l In for m a tion . A standard vacuum system and
Schlenk type glassware were used in most of the experiments
in handling metal complexes, although most of the compounds
are stable enough to be handled in air.
HOTf and DOTf were purchased from Aldrich. [Ir(H)2-
(NCCH3)2(PPh3)2]OTf (1),12 [Ir(-CHdCH2)2(NCCH3)2(PPh3)2]-
OTf (2),2b [Ir(-CHdCHD)2(NCCH3)2(PPh3)2]OTf (2-d 2),2b and
[Ir(-CHdCH2)2(CO)2(PPh3)2]OTf (3)2b were prepared by lit-
erature methods.
In str u m en ta tion . NMR spectra were recorded on a Varian
200 or 500 MHz spectrometer for 1H, 125.7 MHz for 13C, and
81 or 121.3 MHz for 31P. Infrared spectra were obtained on a
Nicolet 205. Elemental analyses were carried out with a Carlo
Erba EA1108 at the Organic Chemistry Research Center,
Sogang University. FD mass measurements were carried out
with a Micro Mass Co. Autospec-Q at the SK research center.
Scheme 2 summarizes the reactions of [Ir(CHdCHD)2-
(CH3CN)2(PPh3)2]+ (2-d 2)2b (Scheme 2). Isotopomers
4-d 1, 4-d 2 ([Ir(η3-CH2DCHCHCHD)(NCCH3)2(PPh3)2]2+),
4-d 3 ([Ir(η3-CHD2CHCHCHD)(NCCH3)2(PPh3)2]2+), 5-d 2
([Ir(η4-CHDdCHCHdCHD)(NCCH3)(PPh3)2]+), 5-d x (1
< x < 2), 10, and 10-d 1 have been unequivocally
Syn th esis of [Ir (η3-CH3-CHCHCH2)(CH3CN)2(P P h 3)2]-
(OTf)2 (4). A reaction mixture of 2 (0.10 g, 0.1 mmol) and HOTf
(11 µL, 0.12 mmol) in CHCl3 (10 mL) was stirred for 1 h at 25
°C before diethyl ether (30 mL) was added to precipitate beige
microcrystals, which were collected by filtration, washed with
diethyl ether (3 × 10 mL), and dried under vacuum. The yield
was 0.11 g and 95% based on [Ir(η3-CH3CHCHCH2)(CH3CN)2-
1
identified by H NMR (4-d 1, 4-d 2, 4-d 3, 5-d 2, and 5-d x)
and mass spectral data (10 and 10-d 1) (see Experimen-
tal Section).
Metal-carbenes (M+dCHCH2R) are frequently ob-
served and suggested in reactions of metal-alkenyls (M-
CHdCHR) with the proton,10 and the R-carbon (M+d
CHCH2R) of the electrophilic alkylidene group readily
interacts with the R-carbon of a neighboring hydrocarbyl
ligand to form a new C-C bond.4,11 Scheme 3 is
accordingly suggested for the C-C bond formation
between adjacent alkenyl groups of 2 (2 f 4). The
formation of 4-d 2 from the reaction of 2-d 2 with H+
suggests the attack of H+ on the â-carbon of an alkenyl
group to give the intermediate A-d 2, which undergoes
a C-C coupling reaction between R-carbons of the
carbene (IrdCHCH2D) and cis-ethenyl (Ir-CHdCHD)
ligands to produce another intermediate, B-d 2. The
complex 4-d 2 is then produced by the isomerization of
complex B-d 2, which also slowly undergoes reductive
deprotonation to produce the stable 18-electron Ir(I)
complex 5-d x (1 < x < 2).
1
(PPh3)2](OTf)2 (4). H NMR (500 MHz, CDCl3): δ 7.2-7.6 (m,
P(C6H5)3, 30H), 5.82 (m, Ir-η3-CH3CHCHCH2, 1H), 4.47 (m,
Ir-η3-CH3CHCHCH2, 1H), 4.30 and 3.37 (both br m, Ir-η3-CH3-
CHCHCH2, 2H), 2.20 and 2.15 (both br s, 2CH3CN, 6H), 1.19
(quartet like, Ir-η3-CH3CHCHCH2, 3H). 13C NMR (125.7 MHz,
CDCl3): δ 122.6 and 121.2 (s, 2CH3CN), 116.6 (s, Ir-η3-CH3-
CHCHCH2), 84.2 (br s, Ir-η3-CH3CHCHCH2), 62.5 (br s, Ir-η3-
CH3CHCHCH2), 16.4 (s, Ir-η3-CH3CHCHCH2), 4.7 (br s, 2CH3-
CN), 133.4, 132.3, 129.4 and 127.8. (P(C6H5)3). HETCOR (1H
(500 MHz) f 13C (125.7 MHz)): δ 5.82 f 116.6; 4.47 f 84.2;
4.30, 3.37 f 62.5; 2.20, 2.15 f 4.7; 1.19 f 16.4. HOMOCOSY
1
(1H (500 MHz) f H (500 MHz)): δ 5.82 f 4.47, 4.30, 3.37;
4.47 f 5.82, 1.19; 4.30 f 5.82; 3.37 f 5.82, 1.19; 1.19 f 4.47,
3.37. 31P{1H} NMR (81 MHz, CDCl3): δ -9.59 (s, PPh3). IR
(KBr, cm-1): 1261, 1158, and 1031 (s, OTf-). Anal. Calcd for
Ir1P2O6S2F6N2C46H43: C, 47.95; N, 2.43; H, 3.76. Found: C,
47.96; N, 2.27; H, 3.70.
Syn th esis of [Ir (η3-CH2DCHCHCH2)(CH3CN)2(P P h 3)2]-
(OTf)2 (4-d 1). Reaction with deutrated acid, DOTf, was carried
out in the same manner as described above for that of 2 with
HOTf. 1H NMR (500 MHz, CDCl3): δ 7.2-7.6 (m, P(C6H5)3,
30H), 5.82 (m, Ir-η3-CH2D-CHCHCH2, 1H), 4.47 (m, Ir-η3-
CH2D-CHCHCH2, 1H), 4.30 and 3.37 (both br m, Ir-η3-CH2-
DCHCHCH2, 2H), 2.20 and 2.15 (both br s, 2CH3CN, 6H), 1.19
(quartet like, Ir-η3-CH2DCHCHCH2, 2H).
Syn th esis of [Ir (η3-CH2DCHCHCHD)(CH3CN)2(P P h 3)2]-
(OTf)2 (4-d 2). Reaction of 2-d 2 with HOTf was carried out in
the same manner as described above for that of 2 with HOTf.
1H NMR (500 MHz, CDCl3): δ 7.2-7.6 (m, P(C6H5)3, 30H), 5.82
(br m, Ir-η3-CH2DCHCHCHD, 1H), 4.47 (m, Ir-η3-CH2DCH-
CHCHD, 1H), 4.30 and 3.37 (both br m, Ir-η3-CH2DCHCHCHD,
1H), 2.20 and 2.15 (both br s, 2CH3CN, 6H), 1.19 (br s, Ir-η3-
CH2DCHCHCHD, 2H).
Syn th esis of [Ir (η3-CHD2CHCHCHD)(CH3CN)2(P P h 3)2]-
(OTf)2 (4-d 3). Reaction of 2-d 2 with DOTf was carried out in
the same manner as described above for that of 2 with HOTf.
1H NMR (500 MHz, CDCl3): δ 7.2-7.6 (m, P(C6H5)3, 30H), 5.82
(m, Ir-η3-CHD2CHCHCHD, 1H), 4.47 (m, Ir-η3-CHD2C-HCH-
CHD, 1H), 4.30 and 3.37 (both br m, Ir-η3-CHD2CHCHCHD,
In conclusion, we have observed two different types
of C-C bond forming reactions between the cis alkenyl
groups of 2: (i) proton-initiated C-C bond formation
to produce η3-allyl complexes via proton attack on the
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2122 Organometallics, Vol. 22, No. 10, 2003
Chin et al.
1H), 2.20 and 2.15 (both br s, 2CH3CN, 6H), 1.19 (br s, Ir-η3-
CHD2CHCHCHD, 1H).
Syn th esis of [Ir (-CHdCH-+NMe3)(-CHdCH2)2(CO)-
(P P h 3)2]OTf (8). A solution of 3 (0.1 g, 0.1 mmol) and Me3-
NO (0.019 g, 0.25 mmol) in CHCl3 (10 mL) was stirred under
HCtCH (1 atm) at 25 °C for 30 min before the pale yellow
solution turned light brown. An excess of Me3NO was removed
by extraction with H2O (10 mL). Addition of n-hexane (10 mL)
resulted in precipitation of beige microcrystals, which were
collected by filtration, washed with n-hexane (3 × 10 mL), and
dried under vacuum. The yield was 0.09 g or 87% based on
[Ir(-CHdCH-+NMe3)(-CHdCH2)2(CO)(PPh3)2]OTf (8). 1H NMR
(500 MHz, CDCl3): δ 7.3-7.4 (m, P(C6H5)3 and Ir-CHdCH2,
31H), 6.93 (dd, J (H-H) ) 19.0 Hz, J (H-H) ) 11.5 Hz, Ir-CHd
CH2, 1H), 6.45 (d, J (H-H) ) 15.3 Hz, Ir-CHdCH-N(CH3)3,
1H), 6.19 (d, J (H-H) ) 11.0 Hz) and 5.95 (d, J (H-H) ) 11.5
Hz) (Ir-CHdCHcisHtrans, 2H), 5.38 (d, J (H-H) ) 15.3 Hz, Ir-
CHdCH-N(CH3)3, 1H), 5.04 (d, J (H-H) ) 18.5 Hz) and 4.96
(d, J (H-H) ) 19.0 Hz) (Ir-CHdCHcisHtrans, 2H), 2.50 (s,
N(CH3)3, 9H). 13C NMR (125.7 MHz, CDCl3): δ 176.0 (t, Ir-
CO, J (C-P) ) 5.0 Hz), 137.5 (t, J (C-P) ) 10.0 Hz) and 136.7
(t, J (C-P) ) 13.3 Hz) (Ir-CHdCH2), 135.2 (br s, Ir-CHdCH-
N(CH3)3), 131.6 (t, J (C-P) ) 4.5 Hz, Ir-CHdCH-N(CH3)3),
127.1 (br s) and 125.7 (t, J (C-P) ) 4.5 Hz) (Ir-CHdCH2), 52.6
(s, N(CH3)3), 127.8, 130.2, 130.6, 134.3 (P(C6H5)3). HETCOR
(1H (500 MHz) f 13C (125.7 MHz)): δ ca. 7.3 f 136.7; 6.93 f
137.5; 6.19, 5.04 f 127.1; 5.95, 4.96 f 125.7; 5.38 f 135.2;
2.50 f 52.6. 31P{1H} NMR (81 MHz, CDCl3): δ -16.39 (s,
PPh3). IR (KBr, cm-1): 2027 (s, νCO), 1581 (m, νCdC), 1264, 1159
and 1031 (s, OTf-). Anal. Calcd for Ir1N1F3S1O4P2C47H47: C,
54.64; H, 4.59; N, 1.36. Found: C, 54.13; H, 4.49; N, 1.29.
R ea ct ion of [Ir (η3-CH3CH CH CH2)(CH3CN)2(P P h 3)2]-
(OTf)2 (4) w ith H2: F or m a tion of CH3CHdCHCH3 (m ix-
tu r e of cis a n d tr a n s), CH3CH2CH2CH3, a n d [Ir (H)2-
(CH3CN)2(P P h 3)2]OTf (1). A CDCl3 (5 mL) solution of 4 (0.3
g, 0.26 mmol) was stirred under H2 (1 atm) at 25 °C for 12 h
in a bomb reactor before the reaction mixture was distilled
under vacuum to collect 2-butene (mixture of cis and trans)
and butane in the cold trap of a dry ice/isopropyl alcohol bath.
A CDCl3 solution of 2-butene and butane was measured by
1H NMR. The residue in the bomb reactor was dissolved in
CHCl3 (10 mL). HOTf was removed by extraction with H2O (2
× 10 mL) before n-pentane (10 mL) was added to precipitate
beige microcrystals of [Ir(H)2(NCCH3)2(PPh3)2]OTf (1), which
were collected by filtration, washed with n-pentane (3 × 10
mL), and dried under vacuum. The yield was 0.24 g or 97%
based on compound 1.
Syn th esis of [Ir (η4-CH2dCHCHdCH2)(CH3CN)(P P h 3)2]-
OTf (5). Meth od A. A CHCl3 solution of 2 (0.1 g, 0.1 mmol)
was heated at 60 °C for 48 h before n-pentane (30 mL) was
added to precipitate beige microcrystals, which were collected
by filtration, washed with n-pentane (3 × 10 mL), and dried
under vacuum. The yield was 0.082 g and 85% based on [Ir-
(η4-CH2dCHCHdCH2)(CH3CN)(PPh3)2]OTf (5).
Meth od B. A CHCl3 solution of 4 (0.12 g, 0.1 mmol) was
stirred at 25 °C for 48 h before n-pentane (30 mL) was added
to precipitate beige microcrystals, which were collected by
filtration, washed with n-pentane (3 × 10 mL), and dried under
vacuum. The yield was 0.064 g and 67% based on compound
1
5. H NMR (500 MHz, CDCl3): δ 7.0-7.8 (m, P(C6H5)3, 30H),
6.15 and 5.15 (m, Ir-η4-CH2dCHCHdCH2, 2H), 3.14 and 1.81
(m, Ir-η4-CHsyn
H
antidCHCHdCHsynHanti, 2H), 2.03 (s, CH3CN,
3H), -0.49 and -0.66 (m, Ir-η4-CHsyn
H
antidCHCHdCHsynHanti
,
2H). 13C NMR (125.7 MHz, CDCl3): δ 120.2 (s, Ir-NCCH3), 92.3
(t, J (C-P) ) 4.4 Hz) and 85.5 (d, J (C-P) ) 4.8 Hz) (Ir-η4-
CH2dCHCHdCH2), 41.2 (d, J (C-P) ) 39.0 Hz) and 20.1 (d,
J (C-P) ) 27.3 Hz) (Ir-η4-CH2dCHCHdCH2), 3.6 (s, Ir-
NCCH3). 31P{1H} NMR (81 MHz, CDCl3): δ 15.2 (d, J (P-P) )
8.3 Hz), -8.0 (d, J (P-P) ) 8.3 Hz). IR (KBr, cm-1): 1274, 1095,
and 1033 (s, OTf-). Anal. Calcd for Ir1P2O3S1F3N1C43H39: C,
53.74; N, 1.46; H, 4.09. Found: C, 53.82; N, 1.39; H, 4.18.
Syn th esis of [Ir (η4-CHDdCHCHdCHD)(CH3CN)(P P h 3)2]-
OTf (5-d 2). Heating a CHCl3 solution of 2-d 2 was carried out
in the same manner as method A in the synthesis of complex
1
5. H NMR (500 MHz, CDCl3): δ 7.0-7.8 (m, P(C6H5)3, 30H),
6.15 and 5.15 (m, Ir-η4-CHDdCHCHdCHD, 2H), 3.14, 1.81,
-0.49 and -0.66 (m, Ir-η4-CHDdCHCHdCHD, 2H), 2.03 (s,
CH3CN, 3H).
Syn th esis of [Ir (η4-CHDdCHCHdCHD)(CH3CN)(P P h 3)2]-
OTf (5-d x). Stirring a CHCl3 solution of 4-d 2 was carried out
in the same manner as method B in the synthesis of complex
1
5. H NMR (500 MHz, CDCl3): δ 7.0-7.8 (m, P(C6H5)3, 30H),
6.15 and 5.15 (m, Ir-η4-CHDdCHCHdCHD, 2H), 3.14, 1.81,
-0.49, and -0.66 (m, Ir-η4-CHDdCHCHdCHD, xH (1 < x <
2)), 2.03 (s, CH3CN, 3H).
Syn th esis of [Ir (-CHdCH-+NEt3)(η4-CH2dCHCHdCH2)-
(P P h 3)2]OTf (6). A CHCl3 solution of 2 (0.1 g, 0.1 mmol) and
NEt3 (0.015 g, 0.15 mmol) was stirred under HCtCH (1 atm)
at 25 °C for 1 h before the pale yellow solution turned light
brown. An excess of NEt3 was removed by extraction with H2O
(5 × 10 mL). Addition of n-pentane (10 mL) resulted in
precipitation of beige microcrystals, which were collected by
filtration, washed with cold n-pentane (3 × 10 mL), and dried
under vacuum. The yield was 0.103 g and 98% based on [Ir-
(-CHdCH-+NEt3)(η4-CH2dCHCHdCH2)(PPh3)2]OTf (6). 1H
NMR (500 MHz, CDCl3): δ 7.0-7.4 (m, P(C6H5)3 and Ir-CHd
CH-NEt3, 31H), 5.39 and 5.20 (m, Ir-η4-CH2dCHCHdCH2,
2H), 4.94 (d, J (H-H) ) 15.0 Hz, Ir-CHdCH-NEt3, 1H), 2.84
(q, J (H-H) ) 7.0 Hz, Ir-CHdCH-N(CH2CH3)3, 6H), 2.23, and
Rea ction s of Ir (-CtCR)(η4-CH2dCHCHdCH2)(P P h 3)2
(7, R ) P h (a ), p-C6H4CH3 (b)) w ith CO (1 a tm ): F or m a -
tion of CH2dCHCHdCH2 a n d Ir (-CtCR)(CO)(P P h 3)2. A
CDCl3 (5 mL) solution of 7a (0.3 g, 0.34 mmol) was stirred
under CO (1 atm) at 25 °C for 1 h in a bomb reactor before
the reaction mixture was distilled under vacuum to collect 1,3-
butadiene in the cold trap of a dry ice/isopropyl alcohol bath.
1
The 1,3-butadiene was measured by H NMR. The residue in
the bomb reactor was dissolved in CHCl3 (5 mL), and n-
pentane (10 mL) was added to precipitate yellow microcrystals
of Ir(-CtCPh)(CO)(PPh3)2, which were collected by filtration,
washed with n-pentane (3 × 10 mL), and dried under vacuum.
The yield was 0.28 g or 94% based on Ir(-CtCPh)(CO)(PPh3)2.
1.93 (m, Ir-η4-CHsyn
H) ) 7.0 Hz, Ir-CHdCH-N(CH2CH3)3, 9H), -0.63, and -0.75
(m, Ir-η4-CHsyn antidCHCHdCHsynHanti, 2H). 13C NMR (125.7
HantidCHCHdCHsynHanti, 2H), 0.84 (t, J (H-
H
MHz, CDCl3): δ 128.3 (d, J (C-P) ) 4.1 Hz, Ir-CHdCH-+NEt3),
123.9 (dd, J (C-P) ) 12.9 Hz, J (C-P) ) 4.7 Hz, Ir-CHdCH-
+NEt3), 88.9 (d, J (C-P) ) 4.5 Hz) and 80.5 (dd, J (C-P) ) 7.9
Hz, J (C-P) ) 4.5 Hz) (Ir-η4-CH2dCHCHdCH2), 53.0 (s, Ir-
CHdCH-+N(CH2CH3)3), 42.0 and 31.3 (s, Ir-η4-CH2dCHCHd
CH2), 7.3 (s, Ir-CHdCH-+N(CH2CH3)3). HETCOR (1H (500
MHz) f 13C (125.7 MHz)): δ ca. 7.2 f 123.9; 5.39 f 80.5;
5.20 f 88.9; 4.94 f 128.3; 2.84 f 53.0; 2.23 f 42.0; 1.93 f
31.3; 0.84 f 7.3; -0.63 f 31.3; -0.75 f 42.0. 31P{1H} NMR
(121.3 MHz, CDCl3): δ 5.62 (d, J (P-P) ) 19.4 Hz), -7.12 (d,
J (P-P) ) 19.4 Hz). IR (KBr, cm-1): 1120, 1092, and 1011 (s,
OTf-). Anal. Calcd for Ir1P2O3S1F3N1C49H53: C, 56.20; N, 1.34;
H, 5.10. Found: C, 56.26; N, 1.29; H, 5.14.
13
Compounds Ir(-CtCR)(CO)(PPh3)2 (R ) Ph, p-C6H4CH3)
have been identified by 1H NMR and IR spectral measure-
ments.
Rea ction s of [Ir (η3-CH3CHCHCH2)(CH3CN)2(P P h 3)2]-
(OTf)2 (4) w ith NR′3 (NR′3 ) NC5H5 (a ), NEt3 (b)): F or m a -
tion of [tr a n s-CH3CHdCHCH2NR′3]OTf (10). These reac-
tions were carried out in the same manner as described below
for 4 with NC5H5. A light brown solution of 4 (0.35 g, 0.30
mmol) and NC5H5 (0.023 g, 0.30 mmol) in CHCl3 (10 mL) was
(13) (a) Brown, C. K.; Georgiou, D.; Wilkinson, G. J . Chem. Soc. (A)
1971, 3120. (b) Chin, C. S.; Oh, M.; Won, G.; Cho, H.; Shin, D. Bull.
Korean Chem. Soc. 1999, 20, 85.

C-C Bonds between Adjacent Alkenyl Ligands
Organometallics, Vol. 22, No. 10, 2003 2123
stirred at 25 °C under N2 for 1 h before H2O (5 mL) was added
to the reaction mixture. The unidentified metal complexes
were removed by extraction with CHCl3 (3 × 10 mL), and a
colorless oil was obtained from the distillation of the layer of
H2O at 50 °C under vacuum. The yield was 0.29 mmol and
97% based on [trans-CH3CHdCHCH2NC5H5]OTf (10a ) mea-
reactions were carried out in the same manner as described
above for the reactions of 4 with NC5H5.
[tr a n s-CH2DCHdCHCH2NC5H5]OTf (10a -d 1). 1H NMR
(500 MHz, CDCl3): δ 8.00-8.83 (m, NC5H5, 5H), 6.14 (m, CH2-
+
DCHdCHCH2+NC5H5, 1H), 5.70 (m, CH2DCHdCHCH2
-
NC5H5, 1H), 5.17 (d, J (H-H) ) 7.0 Hz, CH2DCHdCHCH2-
+NC5H5, 2H) 1.77 (d, J (H-H) ) 6.5 Hz, CH2DCHdCHCH2-
+NC5H5, 2H). MS (FD): m/z 135 (M - OTf).
[tr a n s-CH2DCHdCHCH2NEt3]OTf (10b-d 1). 1H NMR
(200 MHz, CDCl3): δ 6.13 (m, CH2DCHdCHCH2+NEt3, 1H),
5.48 (m, CH2DCHdCHCH2+NEt3, 1H), 3.72 (d, J (H-H) ) 7.4
Hz, CH2DCHdCHCH2+NEt3, 2H), 3.20 (q, J (H-H) ) 7.4 Hz,
N(CH2CH3)3, 2H), 1.80 (d, J (H-H) ) 7.4 Hz, CH2DCHd
CHCH2+NEt3, 2H), 1.30 (t, J (H-H) ) 7.4 Hz, N(CH2CH3)3,
3H). MS (FD): m/z 157 (M - OTf).
1
sured by H NMR.
[tr a n s-CH3CHdCHCH2NC5H5]OTf (10a ). 1H NMR (500
MHz, CDCl3): δ 8.03 - 8.93 (m, NC5H5, 5H), 6.19 (m, CH3-
CHdCH-CH2+NC5H5, 1H), 5.74 (m, CH3CHdCHCH2+NC5H5,
1H), 5.22 (d, J (H-H) ) 7.0 Hz, CH3CHdCH-CH2-+NC5H5, 2H)
1.80 (d, J (H-H) ) 6.5 Hz, CH3CHdCHCH2+NC5H5, 3H). 13C
NMR (125.7 MHz, CDCl3): δ 145.4, 144.3, and 128.4 (s,
NC5H5), 138.2 (s, CH3CHdCHCH2+NC5H5), 122.2 (s, CH3CHd
CHCH2+NC5H5), 63.7 (s, CH3CHdCHCH2+NC5H5), 17.9 (s,
CH3CHdCHCH2+NC5H5). HETCOR (1H (500 MHz) f 13C
(125.7 MHz)): δ 6.19 f 138.2; 5.74 f 122.2; 5.22 f 63.7; 1.80
f 17.9. IR (KBr, cm-1): 1262, 1163, and 1033 (s, OTf-). MS
(FD): m/z 134 (M - OTf). No NOE enhancement are observed
between olefinic protons (CH3CHdCHCH2+NC5H5).
Ack n ow led gm en t. The authors wish to thank the
Korea Research Foundation (KRF) for their financial
support of this study through the Basic Science Re-
search Institute program (Grant No. 2000-015-DP0224).
[tr a n s-CH3CHdCHCH2-NEt3]OTf (10b). 1H NMR (200
MHz, CDCl3): δ 6.13 (m, CH3CHdCHCH2+NEt, 1H), 5.48 (m,
CH3CHdCHCH2+NEt, 1H), 3.72 (d, J (H-H) ) 7.4 Hz, CH3-
CHdCHCH2+NEt3, 2H), 3.20 (q, J (H-H) ) 7.4 Hz, N(CH2-
CH3)3, 2H), 1.80 (d, J ) 7.4 Hz, CH3CHdCHCH2+NEt3, 3H),
1.30 (t, J (H-H) ) 7.4 Hz, N(CH2CH3)3, 3H). MS (FD): m/z
156 (M - OTf).
Su p p or tin g In for m a tion Ava ila ble: 1H NMR (for 4, 4-d 1,
4-d 2, 5, 6, 8, 10a , and 10a -d 1), 13C NMR (for 4, 5, 6, 8, and
10a ), 1H, 13C-2D HETCOR (for 4, 6, 8 and 10a ), and 31P NMR
(for 5 and 6) data. This material is available free of charge
via the Internet at http://pubs.acs.org.
Rea ction of [Ir (η3-CH2DCHCHCH2)(CH3CN)2(P P h 3)2]-
(OTf)2 (4-d 1) w ith NR′3 (NR′3 ) NC5H5 (a ), NEt3 (b)). These
OM030090R