Synthesis of metallacyclobutenes of late transition metals via nucleophilic addition of allenyl or propargyl complexes

Article abstract of DOI:10.1021/om9708642

The regioselective addition of NEt₃, PPh₃, or pyridine to the central carbon of a cationic η³-allenyl/propargyl complex of platinum, {Pt(PPh₃)₂(η³-C₃H ₃)}(BF₄

Full text of DOI:10.1021/om9708642

Organometallics 1998, 17, 2953-2957
2953
Syn th esis of Meta lla cyclobu ten es of La te Tr a n sition
Meta ls via Nu cleop h ilic Ad d ition of Allen yl or P r op a r gyl
Com p lexes
Yuan-Chung Cheng, Yu-Kun Chen, Tsang-Miao Huang, Chao-Ining Yu,
Gene-Hsiang Lee, Yu Wang, and J wu-Ting Chen*
Department of Chemistry, National Taiwan University, Taipei, Taiwan 106, Republic of China
Received October 6, 1997
The regioselective addition of NEt3, PPh3, or pyridine to the central carbon of a cationic
η3-allenyl/propargyl complex of platinum, {Pt(PPh3)2(η3-C3H3)}(BF4) (1), leads to the formation
of the new cationic platinacyclobutenes {(PPh3)2Pt[CH2C(Nu)CH]}(BF4) (Nu ) NEt3 (2a ),
PPh3 (2b), C5H5N (2c)) via formation of a C-N or C-P bond, respectively. Complex 2c can
transform into {cis-Pt(PPh3)2(Py)(η1-CHCCH2)}(BF4) (3). The reverse reaction has not been
observed. It is suggested that nucleophilic addition of 1 likely involves external attack at
the central carbon of the η3-allenyl/propargyl ligand. Protonation of 2b yields {Pt(PPh3)2-
[η3-CH2C(PPh3)CH2]}(BF4)2 (7). Addition of PPh3 to a labile η1-allenyliridium complex, (OC-
6-42)-Ir(Cl)(PPh3)2(OTf)(CO)(η1-CHCCH2) (4), results in the iridacyclobutene {(Cl)(PPh3)2-
(CO)Ir[CH2C(PPh3)CH]}(OTf) (5). The single-crystal X-ray structure of 5 has been determined.
Sch em e 1
In tr od u ction
Metallacyclobutenes are important organometallic
species that are involved in processes of metathesis1 and
polymer synthesis.2 Tebbe, Parshall, and their co-
workers led this field with studies of titanacyclobutenes.3
Other workers have developed coupling reactions be-
tween metal carbene complexes and acetylenes as a
useful route to such compounds (Scheme 1).4,5 Metal-
lacyclobutenes of late transition metals were unknown
until Semmelhack et al. prepared ferracyclobutenes
using the same approach.6 These studies were extended
later to the preparation of metallacyclobutenes of cobalt,
rhodium, iridium, and platinum.7
A new synthetic route, the addition of soft nucleo-
philes to a cationic η3-allenyl/propargyl rhenium com-
plex to give a rhenacyclobutene complex, was reported
by Casey and co-workers.8 We and others have inde-
pendently developed the addition reactions of cationic
η3-allenyl/propargyl complexes of the late transition
metals as a route to central-carbon-substituted η3-allyl
complexes, η3-trimethylenemethane complexes, and η3-
oxa- and η3-azatrimethylenemethane complexes.9 Den-
(7) For a review: (a) J ennings, P. W.; J ohnson, L. L. Chem. Rev.
1994, 94, 2241. For Co: (b) Wakatsuki, Y.; Miya, S.; Yamazaki, H. J .
Chem. Soc., Dalton Trans. 1986, 1201. (c) O’Connor, J . M.; J i, H.-L.;
Iranpour, M.; Rheingold, A. L. J . Am. Chem. Soc. 1993, 115, 1586. (d)
O’Connor, J . M.; J i, H.-L.; Rheingold, A. L. J . Am. Chem. Soc. 1993,
115, 9846. (e) O’Connor, J . M.; Fong, B. S.; J i, H.-L.; Hiibner, K.;
Rheingold, A. L. J . Am. Chem. Soc. 1995, 117, 8029. For Rh: (f) Fisch,
P. D.; Khare, G. P. J . Organomet. Chem. 1977, 142, C61. (g) Werner,
H.; Heinemann, A.; Windmu¨ller, B.; Steinert, P. Chem. Ber. 1996, 129,
903. For Ir: (h) Tuggle, R. M.; Weaver, D. L. Inorg. Chem. 1972, 11,
2237. (i) Calabreses, J . C.; Roe, D. C. Thorn, D. L.; Tulip, T. H.
Organometallics 1984, 3, 1223. (j) O’Connor, J . M.; Pu, L.; Woolard,
S.; Chadha, R. K. J . Am. Chem. Soc. 1990, 112, 6731. (k) Burgess, J .;
Kemmit, R. D. W.; Morton, N.; Mortimer, C. T.; Wilkinson, M. P. J .
Organomet. Chem. 1980, 191, 477. (l) Forcolin, S.; Pellizer, G.; Graziani,
M.; Lenarda, M.; Ganzerla, R. J . Organomet. Chem. 1980, 194, 203.
(m) Hemond, R. C.; Hughes, R. P.; Robinson, D. J .; Rheingold, A. L.
Organometallics 1988, 7, 2239. (n) Hughes, R. P.; King, M. E.;
Robinson, D. J .; Spotts, J . M. J . Am. Chem. Soc. 1989, 111, 8919.
(8) (a) Casey, C. P.; Yi, C. S. J . Am. Chem. Soc. 1992, 114, 6597. (b)
Casey, C. P.; Nash, J . R.; Yi, C. S.; Selmeczy, A. D.; Chung, S.; Powell,
D. R.; Hayashi, R. K. J . Am. Chem. Soc. 1998, 120, 722.
(9) (a) Huang, T.-M.; Chen, J .-T.; Lee, G.-H.; Wang, Y. J . Am. Chem.
Soc. 1993, 115, 1170. (b) Baize, M. W.; Furilla, J . L.; Wojcicki, A. Inorg.
Chim. Acta 1994, 233, 1. (11) (c) Plantevin, V.; Blosser, P. W.; Gallucci,
J . C.; Wojcicki, A. Organometallics 1994, 13, 3651. (d) Baize, M. W.;
Plantevin, V.; Gallucci, J . C.; Wojcicki, A. Inorg. Chim. Acta 1995, 235,
1. (e) Ogoshi, S.; Tsutsumi, K.; Kurosawa, H. J . Organomet. Chem.
1995, 493, C19. (f) Ogoshi, S.; Tsutsumi, K.; Ooi, M.; Kurosawa, H. J .
Am. Chem. Soc. 1995, 117, 10415. (g) Baize, M. W.; Blosser, P. W.;
Plantevin, V.; Schimpff, D. G.; Gallucci, J . C.; Wojcicki, A. Organome-
tallics 1996, 15, 164. (h) Tsai, F.-Y.; Chen, J .-T.; Lee, G.-H.; Wang, Y.
J . Organomet. Chem. 1996, 520, 85.
(1) (a) Tebbe, F. N.; Parshall, G. W.; Reddy, G. S. J . Am. Chem. Soc.
1978, 100, 3611. (b) Grubbs, R. H. Prog. Inorg. Chem. 1978, 24, 1.
(2) (a) Grubbs, R. H.; Tumas, W. Science 1989, 243, 907 and
references therein. (b) Fox, H. H.; Wolf, M. O.; O’Dell, R.; Lin, B. L.;
Schrock, R. R.; Wrighton, M. S. J . Am. Chem. Soc. 1994, 116, 2827
and references therein.
(3) Tebbe, F. N.; Parshall, G. W.; Ovenall, D. W. J . Am. Chem. Soc.
1979, 101, 5074.
(4) Tebbe, F. N.; Harlow, R. L. J . Am. Chem. Soc. 1980, 102, 6149.
(5) McKinney, R. J .; Tulip, T. H.; Thorn, D. L.; Coolbaugh, T. S.;
Tebbe, F. N. J . Am. Chem. Soc. 1981, 103, 5584.
(6) (a) Semmelhack, M. F.; Tamura, R.; Schnatter, W.; Springer, J .
J . Am. Chem. Soc. 1984, 106, 5363. (b) Wakatsuki, Y.; Miya, S.;
Yamazaki, H.; Ikuta, S. J . Chem. Soc., Dalton Trans. 1986, 1201. (c)
Lisko, J . R.; J ones, W. M. Organometallics 1985, 4, 944. (d) Conti, N.
J .; J ones, W. M. Organometallics 1988, 7, 1666. (e) Conti, N. J .;
Croether, D. J .; Tivakornpannarai, S.; J ones, W. M. Organometallics
1990, 9, 175.
S0276-7333(97)00864-9 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 06/18/1998

2954 Organometallics, Vol. 17, No. 14, 1998
Cheng et al.
Sch em e 2
Pt[CH2C(Py)CH]}(BF4) (2c) in 91% yield based on NMR
integration. When the solution of 2c was brought to
-20 °C, another platinum complex that exhibits a
characteristic η1-allenyl signature was formed. The two
31P doublets at δ 8.36 and 24.86 with J P-P ) 16.4 Hz
and J P-Pt ) 3662 and 2113 Hz, respectively, suggest
that it is a cis square-planar complex. The pyridine
signals were found to indicate coordination. We assign
this product as cis-[Pt(PPh3)2(Py)(η1-CHCCH2)](BF4) (3)
accordingly. The relative abundance of 2c:3:1 changed
from 0.64:0.23:0.13 after 30 min to 0.57:0.30:0.14 after
8 h. When the temperature of the solution was raised
to 0 °C for 20 min, the amount of complex 3 accounted
for 85% of the starting amount of 1. Complexes 1 and
2c were not observed after that point, no matter how
much the temperature was changed. Leaving 3 in
solution at 25 °C caused the formation of a mixture of
platinum complexes of η3-2-hydroxyallyl and η3-oxatri-
methylenemethane and diplatina-η6-diallyl ether.11 One
may infer that 1 can undergo nucleophilic attack either
at the central carbon to give 2c or at the metal center
to give 3. Complex 2c is the kinetic product, and 3 is
the thermodynamic product. Both products can revert
to 1 by losing pyridine. The moisture that penetrated
into the reaction vessel is blamed for hydrolyzing 1 to
the hydroxyallyl complex and its ensuing byproducts of
η3-O-TMM and η6-diallyl ether complexes (Scheme 4).
The reactions of other (η1-allenyl)platinum complexes
such as trans-Pt(PPh3)2(Br)(η1-CHCCH2) and PPh3 do
not result in metallacyclobutene. The addition reaction
of an octahedral (η1-allenyl)iridium complex, however,
was observed. Stirring a mixture of (OC-6-42)-Ir(Cl)-
(PPh3)2(OTf)(CO)(η1-CHCCH2) (4)12 and PPh3 at -15 °C
for 30 min caused a color change from reddish brown
to yellow. The iridacyclobutene complex {(Cl)(PPh3)2-
Sch em e 3
sity functional caculations indicate that metallacy-
clobutenes are likely the kinetic intermediates in such
addition reactions (Scheme 2).10 We report here the first
examples of the synthesis of platina- and iridacy-
clobutene complexes via addition of nitrogen- and
phosphorus-centered nucleophiles to either (η1-allenyl)-
or (η3-allenyl/propargyl)metal complexes.
Resu lts a n d Discu ssion
The reactions of the (η3-allenyl/propargyl)platinum
complex {Pt(PPh3)2(η3-C3H3)}(BF4) (1) with an equimo-
lar amount of Et3N or Ph3P in chloroform or methylene
dichloride at -40 °C readily gave the cationic platina-
cyclobutene complexes {(PPh3)2Pt[CH2C(Nu)CH]}(BF4)
(Nu ) NEt3 (2a ), PPh3 (2b)) (Scheme 3). Complex 2a
decomposes on drying in vacuo, presumably due to
evaporation of Et3N. We have characterized 2a by NMR
spectroscopy. Complex 2b is more stable and has been
isolated by crystallization below 0 °C.
(CO)Ir[CH2C(PPh3)CH]}(OTf) (5) was isolated in 78%
yield (Scheme 5). The 31P NMR data indicate that two
phosphine ligands in 5 are in a trans arrangement. The
1H and 13C NMR data of the metallacyclobutene moiety
of 5 are consistent with those of 2a -c and the docu-
mented iridacyclobutenes.7i,j The carbonyl ligand of 5
is evidenced by an IR band at 2035 cm-1 and a 13C NMR
resonance at δ 171.5.
The two magnetically nonequivalent phosphine ligands
of 2a or 2b suggest that these complexes have a cis
square-planar configuration. The carbon-bound phos-
phorus in 2b shows smaller values of J P-Pt (703.8 Hz)
compared to those of the Pt-bound Ph3P ligands (J P-Pt
1
) 2115, 2226 Hz). In the H NMR spectra, the meth-
ylene protons, unlike the diastereotopic protons in
rhenacyclobutenes,8 give rise to one characteristic reso-
nance at high field, δ 0.03 (J H-P ) 81.9 Hz, J H-Pt ) 81.9
Hz) for 2a and δ 0.18 (J H-H ) 4.7 Hz, J H-P ) 81.9 Hz,
J H-Pt ) 85.8 Hz) for 2b. The equivalency of the
hydrogens of the Pt-bound CH2 suggest that the met-
allacycle overlaps with the molecular plane and bisects
H-C-H. Similar NMR features have been found
previously for other metallacyclobutenes.3-8 The meth-
ine resonance of 2a is found at δ 6.01 (J H-Pt ) 25.9 Hz).
For 2b, this resonance is in the region of the phenyl
signals and was detected by 2D H-H and C-H COSY.
The 13C NMR resonances for the Pt-CH2 carbons are
also at high field, δ -6.07 (J C-Pt ) 79.4 Hz) for 2a and
δ -12.6 (J C-Pt ) 83.5 Hz) for 2b. The olefinic carbons
appear at δ 123.1 and 142.2 for 2a and at δ 136.3 and
161.1 for 2b.
Single crystals of 5 were grown from a CH2Cl2/Et2O
solution, and an X-ray diffraction study was carried
out. An ORTEP drawing showing the molecular struc-
ture of 5 is depicted in Figure 1. The metallacycle
moiety, Pt-C2-C3-C4-P1, is quite coplanar, with the
largest out-of-plane deviation at C3 being 0.04(2) Å
and the mean deviation being 0.02 Å; X2 is 8.25. The
length of C2-C3 is consistent with a double bond, and
Ir-C2(sp2) and Ir-C4(sp3) are in the single-bond re-
gion. Comparisons of important structural data be-
tween 5 and the closely related complex (Br)(PMe3)3-
Ir[CH2C(p-Tol)C(p-Tol)] (5′)7i are listed in Table 1, which
show excellent consistency with each other and with
other titana-,4,5 platina-,7m,n and rhenacyclobutenes.8b
Two valence tautomers of metallacyclobutene, carbene
(11) Huang, T.-M.; Hsu, R.-H.; Yang, C.-S.; Chen, J .-T.; Lee, G.-H.;
Wang, Y. Organometallics 1994, 13, 3657.
(12) (a) Hsu, R.-H.; Chen, J .-T.; Lee, G.-H.; Wang, Y. Organometal-
lics 1997, 16, 1159. (b) Chen, J .-T.; Chen, Y.-K.; Chu, J .-B.; Lee, G.-
H.; Wang, Y. Organometallics 1997, 16, 1476.
The reaction of 1 and pyridine at -40 °C immedi-
ately resulted in the formation of metastable {(PPh3)2-
(10) Cheng, Y.-C.; Chen, J .-T.; Gin, B.-Y. Unpublished results.

Metallacyclobutenes of Late Transition Metals
Organometallics, Vol. 17, No. 14, 1998 2955
Sch em e 4
Sch em e 5
acetylene complexes (5b) and η3-vinylcarbene complexes
(5c), have been structurally characterized.13,14 By judg-
ing the X-ray data for 5 and for species 5b and 5c, we
unequivocally classify complex 5 to be the extreme form
of metallacyclobutene, 5a .
The reaction of 4 with pyridine, which is less bulky
than PPh3, does not give a metallacyclobutene product.
The replacement of pyridine for the triflate of 4, instead
of addition of pyridine to the allenyl ligand, takes place
and gives (OC-6-42)-Ir(Cl)(PPh3)2(Py)(CO)(η1-CHCCH2)
(6).12b Such a reactivity again supports the notion that
the formation of metallacyclobutenes likely is due to
external nucleophilic attack at the central carbon of an
η3-allenyl/propargyl ligand (Scheme 6). Metallacy-
clobutenes have been invoked as the kinetic intermedi-
ates of the formation of central-carbon-substituted η3-
allyl complexes from nucleophilic addition of η1-allenyl
and η3-allenyl/propargyl complexes.8-11,15 A reaction
resulting in the formation of {Pt(PPh3)2[η3-CH2C(PPh3)-
CH2]}(BF4)2 (7) from protonation of 2b affords sound
evidence for the former pathway (Scheme 7). On the
other hand, insertion of coordinated allene into an M-L
bond also was considered to be a possibility.16
F igu r e 1. ORTEP drawing of {(Cl)(PPh3)2(CO)Ir[CH2C-
(PPh3)CH]}(OTf) (5) with 50% probability ellipsoids. The
hydrogen atoms and the anion are omitted for clarity.
Ta ble 1. Bon d Com p a r ison of 5 a n d 5′
5
5′
Ir-C2
Ir-C4
C2-C3
C3-C4
2.08(2)
2.23(2)
1.39(2)
1.53(3)
Ir-C1
Ir-C3
C1-C2
C2-C3
2.134(5)
2.166(6)
1.344(8)
1.525(7)
C2-Ir-C4
C2-C3-C4
Ir-C2-C3
Ir-C4-C3
66.9(7)
109(2)
97(1)
C1-Ir-C3
C1-C2-C3
Ir-C1-C2
Ir-C3-C2
64.5(2)
106.1(5)
98.0(3)
91.2(3)
87(1)
In conclusion, regioselective addition to the η3-allenyl/
propargyl or η1-allenyl complexes provides an alterna-
tive methodology for the synthesis of metallacyclobutenes.
(13) (a) Foley, H. C.; Strubinger, L. M.; Targos, T. S.; Geoffroy, G.
L. J . Am. Chem. Soc. 1983, 105, 3064.
(14) (a) Nakatsu, K.; Mitsudo, T.; Nakanishi, H.; Watanabe, Y.;
Takegami, Y. Chem. Lett. 1977, 1447. (b) Klimes, J .; Weiss, E. Angew.
Chem., Int. Ed. Engl. 1982, 21, 205. (c) Mayr, A.; Asaro, M. F.; Glines,
T. J . J . Am. Chem. Soc. 1987, 109, 2215. (d) Garrett, K. E.; Sheridan,
J . B.; Pourreau, D. B.; Feng, W. C.; Geoffroy, G. L.; Staley, D. L.;
Rheingold, A. L. J . Am. Chem. Soc. 1989, 111, 8383. (e) Herrmann,
W. A.; Fischer, R. A.; Herdtweck, E. Angew. Chem., Int. Ed. Engl. 1987,
26, 1263. (f) Fischer, R. A.; Fischer, R. W.; Herrmann, W. A.;
Herdtweck, E. Chem. Ber. 1989, 122, 2035.
Exp er im en ta l Section
Gen er a l Con sid er a tion s. Solvents were dried by stan-
dard procedures. IR spectra were recorded on a Bio-Rad FTS-
(16) (a) Cowan, R. L.; Trogler, W. C. Organometallics 1987, 6, 2451.
(b) Allen, S. R.; Beevor, R. G.; Green, M.; Norman, N. C.; Orpen, A.
G.; Williams, I. D. J . Chem. Soc., Dalton Trans. 1981, 2339. (c) Merola,
J . S. Organometallics 1989, 8, 2975. (d) Wolf, J .; Werner, H. Organo-
metallics 1987, 6, 1164.
(15) Casey, C. P.; Chung, S.; Ha, Y.; Powell, D. R. Inorg. Chim. Acta
1997, 265, 127.

2956 Organometallics, Vol. 17, No. 14, 1998
Cheng et al.
Ta ble 2. X-r a y Cr ysta l P a r a m eter s a n d Da ta
Collection Deta ils for 5
Sch em e 6
formula
fw
cryst dimns, mm
space group
a, Å
C59H48O4P3ClSF3Ir‚2.5H2O
1267.64
0.10 × 0.15 × 0.40
P1h
10.063(5)
12.821(1)
22.353(3)
102.57(1)
99.93(3)
97.12(3)
2733(1)
2
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
F(calcd), Mg m-3
F(000)
1.540
1264
radiation; λ, Å
Mo KR; 0.7107
T, K
298
µ, mm-1
transmission
max 2θ, deg
h, k, l
no. of rflns measd
no. of rflns obsd
no. of variables
R(F)
2.57
0.83-1.0
45
(10, 13, (24
7145
4551 (>2.0σ)
587
Sch em e 7
0.059
Rw(F)
0.059
S
1.88
(∆/σ)max
0.0138
40 spectrophotometer. The NMR spectra were recorded on a
Bruker AC-200 or a ACE-300 spectrometer. Spectrometer
frequencies of 81.015 or 121.496 MHz for 31P NMR, 200.133
or 300.135 MHz for 1H NMR, and 50.323 or 75.469 MHz for
13C NMR spectra were employed. Mass spectrometric analyses
were collected on a J EOL SX-102A spectrometer. Elemental
analyses were done on a Perkin-Elmer 2400 CHN analyzer.
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 5
Ir-Cl
2.502(4)
1.91(2)
1.00(2)
1.83(2)
Ir-P2
Ir-C2
C2-C3
2.383(4)
2.08(2)
1.39(2)
Ir-P3
Ir-C4
C3-C4
2.377(4)
2.23(2)
1.53(3)
Ir-C1
C1-O1
C3-P1
Cl-Ir-P2
Cl-Ir-C2
P2-Ir-C1
P3-Ir-C1
90.(1) Cl-Ir-P3
93.7(5) Cl-Ir-C4
88.6(5) P2-Ir-C2
89.5(5) P3-Ir-C2
89.8(1) Cl-Ir-C1
160.6(5) P2-Ir-P3
90.7(4) P2-Ir-C4
91.3(4) P3-Ir-C4
98.5(8) C2-Ir-C4
100.9(7)
177.9(2)
91.5(4)
89.4(4)
66.9(7)
Syn th esis a n d Ch a r a cter iza tion . cis-{(P P h 3)2P t[CH2C-
(NEt3)CH]}(BF 4) (2a ). A two-necked round-bottomed flask
was charged with 1 (45 mg, 0.05 mmol)11 and dry CDCl3 (0.7
mL). Triethylamine (21 µL, 0.05 mmol) was injected into the
solution at -40 °C. The conversion to 2a was quantitative on
the basis of the NMR data. Attempted isolation of 2a by
crystallization resulted in its decomposition even at -20 °C.
31P NMR (CDCl3, 233 K, 81.015 MHz): δ 20.9 (d with 195Pt
satellites, J P-P ) 10.2 Hz, J P-Pt ) 2470 Hz), 21.1 (d with 195Pt
satellites, J P-P ) 10.2 Hz, J P-Pt ) 2335 Hz). 1H NMR (CDCl3,
C1-Ir-C2 165.4(8) C1-Ir-C4
C3-P1-C5 110.8(8) C3-P1-C11 107.8(8) C3-P1-C17 112.0(7)
Ir-C1-O1 172(2)
P1-C3-C4 131(1)
Ir-C2-C3
C2-C3-C4 109(2)
97(1)
P1-C3-C2 120(1)
Ir-C4-C3 87(1)
cis-{(P P h 3)2P t[CH2C(P y)CH]}(BF 4) (2c). The reaction of
1 (45 mg, 0.05 mmol) and pyridine (4.0 µL, 0.05 mmol) in
CDCl3 (0.7 mL) at -40 °C produced 2c in 91% yield based on
the NMR data. 31P NMR (CDCl3, 233 K, 121.496 MHz): δ
19.6 (d with 195Pt coupling, J P-P ) 12.72 Hz, J P-Pt ) 2445 Hz),
21.6 (d with 195Pt coupling, J P-P ) 12.72 Hz, J P-Pt ) 2332 Hz).
1H NMR (CDCl3, 233 K, 200 MHz): δ 0.47 (2H, m with 195Pt
coupling, J H-Pt ) 80.4 Hz, PtCH2), 6.73 (1H, s with 195Pt
coupling, J H-Pt ) 24.6 Hz, PtCH), 6.8-7.3 (m, phenyl H), 8.03
(2H, m, o-HPy), 8.40 (1H, m, p-HPy). 13C NMR (CDCl3, 233 K,
233 K, 200 MHz): δ 0.03 (2H, m with 195Pt coupling, J H-Pt
)
81.9 Hz, PtCH2), 1.12 (9H, t, J H-H ) 6.77 Hz, CH2CH3), 2.99
(6H, q, J H-H ) 6.77 Hz, NCH2), 6.01 (1H, s with 195Pt coupling,
J H-Pt ) 25.9 Hz, PtCH), 7.1-7.3 (30H, m, phenyl H). 13C NMR
(CDCl3, 263 K, 50.323 MHz): δ -6.07 (d, J C-P ) 79.4, PtCH2),
7.36 (s, CH2CH3), 47.0 (s, NCH2), 123.1 (dd, J C-P ) 6.3, 106.8
Hz, PtCH), 127-134 (phenyl carbons), 142.2 (d with 195Pt
satellites, J C-P ) 7.02 Hz, J C-Pt ) 96.5 Hz, CN).
50.32 MHz): δ -4.89 (d, J C-P ) 78.4, PtCH2), 123.7 (d, J C-P
)
cis-{(P P h 3)2P t[CH2C(P P h 3)CH]}(BF4) (2b). A two-necked
round-bottomed flask was charged with [Pt(PPh3)2(η3-C3H3)]-
(BF4) (1;11 45 mg, 0.05 mmol) and dry CDCl3 (1 mL). Addition
of triphenylphosphine (13 mg, 0.05 mmol) to the solution at
-40 °C immediately resulted in the formation of 2b. The solid
product was isolated by crystallization at 0 °C from C6H6/Et2O
in 83% yield (48 mg). 31P NMR (CDCl3, 273 K, 121.496
MHz): δ 8.2 (dd with 195Pt coupling, J P-P ) 38.6 Hz, 21.7 Hz,
J P-Pt ) 703.8 Hz), 19.2 (dd with 195Pt coupling, J P-P ) 10.4
Hz, 38.6 Hz, J P-Pt ) 2226 Hz), 22.4 (dd with 195Pt coupling,
J P-P ) 10.4 Hz, 21.7 Hz, J P-Pt ) 2115 Hz). 1H NMR (CDCl3,
200 MHz): δ 0.18 (dd with 195Pt coupling, J H-H ) 4.7 Hz, J H-P
) 4.4 Hz, J H-Pt ) 85.8 Hz, 2H, PtCH2), 7.35 (PtCH), 6.8-7.8
(m, phenyl H). 13C NMR (CDCl3, 263 K, 50.323 MHz): δ -12.6
(d, J C-P ) 83.5, PtCH2), 127-134 (phenyl carbons), 136.3 (d,
J C-P ) 38.6 Hz, CP), 161.1 (d, J C-P )107.0 Hz, PtCH). MS
(FAB, m/z): 1020.5 (M+ - BF4). Anal. Calcd for PtC57H48P3-
BF4: C, 61.77; H, 4.37. Found: C, 60.85; H, 4.42.
8.32, 151.7 Hz, PtCH), 123.75 (s, m-CPy), 127-134.5 (phenyl
C), 136.4 (s, p-CPy), 143.6 (d, J C-P ) 7.76 Hz, CPy), 144.8 (s,
o-CPy).
cis-[P t(P P h 3)2(η1-CHCCH2)(P y)](BF 4) (3). The temper-
ature of a solution of 2c, first at -40 °C, was raised to 0 °C
for 20 min, which gave 3 in 85% yield based on the NMR data.
31P NMR (CDCl3, 273 K, 121.496 MHz): δ 8.36 (d with 195Pt
coupling, J P-P ) 16.4 Hz, J P-Pt ) 3662 Hz), 24.86 (d with
195Pt coupling, J P-P ) 16.4 Hz, J P-Pt ) 2113 Hz). 1H NMR
(CDCl3, 273 K, 200 MHz): δ 3.48 (2H, m, CH2), 5.02 (1H, m
with 195Pt coupling, J H-Pt ) 47.2 Hz, CH), 6.8-7.8 (33H, m,
phenyl H, Py), 8.37 (2H, m, o-HPy). 13C NMR (CDCl3, 273 K,
50.323 MHz): δ 67.4 (d, J C-P ) 8.2 Hz, CH2), 88.1 (dd, J C-P
)
10.24, 93.6 Hz, CH), 127-135 (phenyl C), 126.0 (s, p-CPy), 138.3
(s, m-CPy), 151.0 (s, o-CPy), 205.5 (s, dCd).
{(Cl)(P P h 3)2(CO)Ir [CH2C(P P h 3)CH]}(OTf) (5). To a two-
necked round-bottomed flask was charged with 4 (200 mg, 0.22

Metallacyclobutenes of Late Transition Metals
Organometallics, Vol. 17, No. 14, 1998 2957
mmol)12 and PPh3 (67 mg, 0.25 mmol), and the CH2Cl2 (15 mL)
was vacuum-transferred. The reaction solution was stirred
at -15 °C for 30 min. The resulting yellow solution was
concentrated, and the product was precipitated by adding
hexane to give 5 in 78% yield (215 mg). IR (KBr pellet): νCO
were determined by a least-squares fit on 25 reflections.
Intensity data were corrected for absorption on the basis of
an experimental ψ rotation curve. The refinement procedure
was by a full-matrix least-squares method including all the
non-hydrogen atoms anisotropically. Hydrogen atoms were
fixed at the ideal geometry and a C-H distance of 1.0 Å; their
isotopic thermal parameters were fixed to the values of the
attached carbon atoms at the convergence of the isotropic
refinement. Atomic scattering factors were taken from ref 17.
Computing programs are from the NRCC SDP VAX package.18
Crystallographic data and selected bond parameters of 5 are
collected in Tables 2 and 3, respectively. Other detailed data
are supplied in the Supporting Information.
2035 cm-1
.
31P NMR (CDCl3, 121.496 MHz): δ -5.33, 3.23
(d, d, J P-P ) 3.65 Hz). 1H NMR (CDCl3, 200 MHz): δ 1.70 (2H,
t, J H-P ) 5 Hz, PtCH2), 6.6-7.7 (35H, m, phenyl H). 13C NMR
(CDCl3, 75.469 MHz): δ -5.49 (t, J C-P ) 6.38 Hz, PtCH2),
118.16 (d, J C-P ) 85.1 Hz, ipso-C of CPPh3), 122.8 (td, J C-P
8.15, 38.4 Hz, CPPh3), 128-135 (phenyl C), 146.0 (t, J C-P
)
)
5.93 Hz, PtCH), 171.5 (t, J C-P ) 8.19 Hz, CO). MS (FAB,
m/z): 1230.30 (M+), 1081.40 (M+ - OTf). Anal. Calcd for
IrC59H48O4F3P3SCl‚2.5H2O: C, 55.57; H, 4.19. Found: C,
56.42; H, 4.01.
Ack n ow led gm en t. We thank the National Science
{P t(P P h 3)2[η3-CH2C(P P h 3)CH2]}(BF 4)2 (7). To a CDCl3
solution (0.5 mL) containing 2b (30 mg, 0.059 mmol) was added
an equimolar amount of HBF4/etherate or CF3CO2H at 25 °C.
The conversion to 7 was over 90% based on the NMR data.
31P NMR (CDCl3, 121.496 MHz): δ 11.1 (J P-Pt ) 4027 Hz),
17.1 (J P-Pt ) 69.3 Hz). 1H NMR (CDCl3, 300 MHz): δ 3.46
(2H, ddd, J H-H ) 1.5 Hz, J H-P ) 1.5, 12.1 Hz syn-H), 4.63 (2H,
ddd, J H-H ) 1.5 Hz, J H-P ) 6.1, 29.9 Hz, J H-Pt ) 47.1 Hz, anti-
H), 7.0-8.0 (35H, m, phenyl H). 13C NMR (CDCl3, 125.773
MHz): δ 74.8 (dd, J C-P ) 5, 14, 38 Hz, J C-Pt ≈ 35 Hz, Ct),
117.9 (d, J C-P ) 87 Hz, Cc), 128-135 (phenyl C).
Council, Taiwan, ROC, for financial support.
Su p p or tin g In for m a tion Ava ila ble: Tables giving the
complete crystal parameters and data collection details, atomic
coordinates and isothermal data, and bond lengths (Å) and
angles (deg) for complex 5 and figures giving the NMR spectra
of 2a -c, 3, and 7 (24 pages). Ordering information is given
on any current masthead page.
OM9708642
(17) International Tables for X-ray Crystallography; Kynoch Press:
Birmingham, England, 1974; Vol. IV.
(18) NRC VAX: Gabe, E. J .; LePage, Y.; Charland, J .-P.; Lee, F. L.;
White, P. S. J . Appl. Crystallogr. 1989, 22, 384.
X-r a y Cr ysta llogr a p h ic An a lysis. Diffraction data were
measured at 298 K on a Nonius CAD-4 diffractometer with
graphite-monochromatized Mo KR radiation. Cell parameters