Palladium-catalyzed reaction of diselenide with isocyanide

Article abstract of DOI:10.1021/om970936p

A Pd-catalyzed reaction providing the first example of insertion of isocyanide into a Pd-Se bond is described. Tetrakis(triphenylphosphine)palladium [Pd(PPH₃)₄] catalyzes the reaction of a diselenide (ArSe)₂ (1a) with an isocyanide ArNC (2) (Ar = 4-MeC₆H₄) to afford the adducts (ArSe)(C=NAr)_m(SeAr) (m = 2, 3). An X-ray crystallographic structure of the palladium intermediate trans-Pd(SeAr)₂(CNAr)(PPh₃) (7a) is determined. In marked contrast to the Pd-catalyzed reaction using a disulfide, the 1:1-adduct 3a (m = 1) is not produced. The stoichiometric reaction of 7a with 1a also did not provide 3a. These facts suggest that the reductive elimination of 1:m-adducts takes place only when more than two isocyanides are inserted into Pd-Se bond(s) of 7a to give Pd[(C=NAr)_p(SeAr)][(C=NAr)_q(SeAr)]L_n (p, q > 0) (10a). In contrast, the reaction of ditelluride (PhTe)₂ (1c) with 2 is not catalyzed by the Pd complex due in part to the insolubility and instability of the palladium(II) tellurolate intermediates.

Full text of DOI:10.1021/om970936p

908
Organometallics 1998, 17, 908-913
P a lla d iu m -Ca ta lyzed Rea ction of Diselen id e w ith
Isocya n id e
Hitoshi Kuniyasu,* Akitugu Maruyama, and Hideo Kurosawa*
Department of Applied Chemistry, Faculty of Engineering, Osaka University,
Suita, Osaka 565, J apan
Received October 27, 1997
A Pd-catalyzed reaction providing the first example of insertion of isocyanide into a Pd-
Se bond is described. Tetrakis(triphenylphosphine)palladium [Pd(PPh3)4] catalyzes the
reaction of a diselenide (ArSe)2 (1a ) with an isocyanide ArNC (2) (Ar ) 4-MeC6H4) to afford
the adducts (ArSe)(CdNAr)m(SeAr) (m ) 2, 3). An X-ray crystallographic structure of the
palladium intermediate trans-Pd(SeAr)2(CNAr)(PPh3) (7a ) is determined. In marked contrast
to the Pd-catalyzed reaction using a disulfide, the 1:1-adduct 3a (m ) 1) is not produced.
The stoichiometric reaction of 7a with 1a also did not provide 3a . These facts suggest that
the reductive elimination of 1:m-adducts takes place only when more than two isocyanides
are inserted into Pd-Se bond(s) of 7a to give Pd[(CdNAr)p(SeAr)][(CdNAr)q(SeAr)]Ln (p, q
g 0) (10a ). In contrast, the reaction of ditelluride (PhTe)2 (1c) with 2 is not catalyzed by
the Pd complex due in part to the insolubility and instability of the palladium(II) tellurolate
intermediates.
Sch em e 1. In ser tion of Isocya n id e in to th e
In tr od u ction
P d -Se Bon d
The insertion of isocyanides into M-Y (M ) transition
metal) bonds is among the most basic reactions in
organometallic chemistry. Most efforts have been fo-
cused on insertion into M-C1 and M-H2 bonds. Only
a few examples of insertion into M-N3 and M-Cl4 bonds
by stoichiometric reactions and M-Si5 bonds by catalytic
reactions have been reported. We recently reported the
palladium-catalyzed reaction of a disulfide with an
isocyanide, which included an unprecedented insertion
of isocyanide into a Pd-S bond.6 This paper describes
the reaction of a diselenide with an isocyanide under
catalytic and stoichiometric conditions, providing the
first evidence of insertion of isocyanide into a Pd-Se
bond (Scheme 1). The differences in reactivity among
chalcogen compounds are also discussed.
Resu lts a n d Discu ssion
The reaction of 4-methylphenyl diselenide (ArSe)2 (1a )
(0.5 mmol) with 4-methylphenyl isocyanide 2 (0.5 mmol)
was carried out in the presence of 2 mol % of Pd(PPh3)4
in benzene (1 mL) at 80 °C for 14 h. The 1H NMR
spectrum of the crude reaction mixture showed the
complete consumption of 2 and the formation of a
complicated mixture. When the reactant was subjected
to preparative TLC, 19% (based on 2) of the 1:2-adduct
4a , 18% of the 1:3-adduct 5a , 80% of 1a (recovered), and
uncharacterized oily products7 were obtained (Scheme
2). In marked contrast to the result using disulfide 1b,6
1:1-adduct 3a was not formed. The reaction using
4-methylphenyl ditelluride (ArTe)2 (1c) was not cata-
lyzed under similar reaction conditions.
To gain more insight into the difference among
dichalcogenides under catalytic conditions, stoichiomet-
ric reactions were conducted in an NMR tube. The
reaction of 1a with Pd(PPh3)4 and subsequently with 2
provided Pd(SeAr)2(CNAr)(PPh3) (7a) (quantitative yield,
cis/ trans ) 8/92) via [Pd(SeAr)2(PPh3)]2 (6a ),8 which is
analogous to the reaction using 1b (Scheme 3).6 In
contrast, the black solid prepared by the reaction of
4-methylphenyl ditelluride (ArTe)2 (1c) with Pd(PPh3)4,
(1) For example, see: (a) Motz, P. L.; Alexander, J . J .; Ho, D. M.
Organometallics 1989, 8, 2589. (b) Yamamoto, Y.; Yamazaki, H. Coord.
Chem. Rev. 1972, 8, 225 and references therein. (c) Ogawa, H.; J oh,
T.; Takahashi, S. J . Chem. Soc., Chem. Commun. 1988, 561. (d)
Onitsuka, K.; Yanai, K.; Takei, F.; J oh, T.; Takahashi, S. Organome-
tallics 1994, 13, 3862. (e) Yamamoto, Y.; Yamazaki, H. Inorg. Chem.
1974, 13, 438. (f) Kosugi, M.; Ogata, T.; Tamura, H.; Sano, H.; Migita,
T. Chem. Lett. 1986, 1197.
(2) (a) Tanase, T.; Ohizumi, T.; Kobayashi, K.; Yamamoto, Y. J .
Chem. Soc., Chem. Commun. 1992, 707. (b) Christian, D. F.; Clark,
H. C. J . Organomet. Chem. 1975, 85, C9.
(3) (a) Chisholm, M. H.; Hammond, C. E.; Ho, D.; Huffman, J . C. J .
Am. Chem. Soc. 1986, 108, 7860. (b) Dormond, A.; Aaliti, A.; Mo¨ıse, C.
J . Chem. Soc., Chem. Commun. 1985, 1231. (c) Saegusa, T.; Ito, Y.;
Kobayashi, S.; Hirota, K.; Yoshioka, H. Tetrahedron Lett. 1966, 6121.
(d) Kienzle, F.; Switzerland, B. Tetrahedron Lett. 1972, 1771. (e) Sawai,
H.; Takizawa, T. Tetrahedron Lett. 1972, 4263.
(4) Crociani, B.; Richards, R. L. J . Chem. Soc., Chem. Commun.
1973, 127.
(5) (a) Ito, Y.; Suginome, M.; Matsuura, T.; Murakami, M. J . Am.
Chem. Soc. 1991, 113, 8899. (b) Ito, Y.; Bando, T.; Matsuura, T.;
Ishikawa, M. J . Chem. Soc., Chem. Commun. 1986, 980. (c) Ito, Y.;
Ito, I.; Hirao, T.; Saegusa, T. Synth. Commun. 1974, 4, 97.
(6) Kuniyasu, H.; Sugoh, K.; Moon, S.; Kurosawa, H. J . Am. Chem.
Soc. 1997, 119, 4669.
(7) The retention time of this oil by HPLC indicated many polymeric
product inclusions. The polarity of the oil by PTLC was so high that
3a would not be contained in it.
(8) Gysling, H. J . In The Chemistry of Organic Selenium and
Tellurium Compounds; Patai, S., Rappoport, Z., Eds.; Wiley: New
York, 1986; Vol. 1, p 679.
S0276-7333(97)00936-9 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 02/12/1998

Palladium-Catalyzed Reaction of Diselenide
Organometallics, Vol. 17, No. 5, 1998 909
Sch em e 2
a
b
Not obtained. Uncharacterized oily products were obtained.
Sch em e 3
Sch em e 4
which was deduced to be [Pd(TeAr)2PPh3]2 (6c) accord-
ing to the literature,9 did not react with 2 (Scheme 4).10
An authentic sample of trans-7a was characterized
crystallographically and found to exhibit approximately
a square-planar coordination geometry with the bond
distances of Se(1)-Pd ) 2.438(3) Å, Se(2)-Pd ) 2.467-
(3) Å, C-Pd ) 1.97(2) Å, P-Pd ) 2.307(5) Å, and N-C
) 1.15(2) Å (Figure 1).11
Contrary to the reaction of Pd(SAr)2(CNAr)(PPh3) (7b)
with 1b , which produced the 1:1-adduct 3b and [Pd-
(SAr)2(PPh3)]2 (6b),6 3a was not obtained by the reaction
of 7a with 1 equiv of 1a (Scheme 3). When 3 equiv of 2
was added into the solution of 7a (prepared in toluene-
d8 by the above procedure), broad peaks were observed
1
at room temperature. The H NMR spectrum taken at
-35 °C showed the sharp peaks of 7a and Pd(SeAr)2-
(CNAr)2 (8a )12 in a ratio of 4:1, indicating fast ligand
exchange of coordinated PPh3 in 7a with free 2 at room
(9) Chia, L. Y.; McWhinnie, W. R. J . Organomet. Chem. 1978, 148,
165.
(10) The corresponding platinum complex Pt(TeAr)2(CNAr)(PPh3)
(7c′) synthesized by the reaction of 1c with Pt(PPh3)4 and 2 was not
stable even at room temperature. So the palladium complex 7c would
not tolerate benzene reflux conditions even if formed.
(11) Crystal data of trans-7: space group P21/a (No. 14) with a )
13.410(3) Å, b ) 18.032(4) Å, c ) 15.005(3) Å, â ) 94.64(2)°, Z ) 4, F
) 1.517 g/cm3, R ) 0.091, and Rw ) 0.069.

910 Organometallics, Vol. 17, No. 5, 1998
Kuniyasu et al.
are incorporated into the palladium complexes as in 10a
does the formation of 1:m-adducts become possible
(Scheme 7).
Moreover, while the 1:2-adduct 4b once formed under
palladium-catalyzed reaction of 1b with 2 hardly be-
came a precursor of the 1:m-adducts (m g 3),6 4a would
easily reenter the catalytic cycle, because the reaction
of 4a with Pd(PPh3)4 gave trans-Pd[(CdNAr)2(SeAr)]-
(SeAr)(PPh3)2 (11a ) even at room temperature (5 min,
10%) (Scheme 8).14 That would explain the low yield of
4a and the formation of an uncharacterized oily product
under the catalytic conditions (Schemes 2 and 7).
Although it is not yet clear why the palladium
complex did not catalyze the reaction of 1c with 2, the
low solubility and instability10 of Pd(II) tellurolate
intermediates might contribute to the lack of the
catalytic activity.
F igu r e 1. ORTEP diagram of trans-7a . Selected bond
lengths (Å): Se(1)-Pd(1) 2.438(3), Se(2)-Pd(1) 2.467(3),
C(1)-Pd(1), 1.97(2), P(1)-Pd(1) 2.307(5), and N(1)-C(1)
1.15(2).
Con clu sion
This paper describes a synthetic and mechanistic
study of the palladium-catalyzed reaction of a diselenide
with an isocyanide to provide the first example of
insertion of isocyanide into a Pd-Se bond. Marked
differences between disulfide and diselenide under Pd-
catalyzed conditions are rationalized on the basis of the
relative propensity toward the reductive elimination of
the 1:1-adduct and 1:m-adducts (m g 2) from the
palladium intermediates 9 and 10.
Sch em e 5
Exp er im en ta l Section
1H, 13C, and 31P NMR spectra in benzene-d6 or CDCl3
solution were recorded with a J EOL J NM-GSX-270 (270 MHz)
or a J EOL J SX-400 (400 MHz) spectrometer. Chemical shifts
in the 1H NMR spectra were recorded relative to Me4Si or C6H6
(δ 7.16). Chemical shifts in the 13C NMR spectra were
recorded relative to Me4Si, C6D6 (δ 128.0), or CDCl3 (δ 77.0).
Chemical shifts in the 31P NMR spectra were recorded using
85% H3PO4 as an external standard. IR spectra were recorded
with a Perkin-Elmer model 1600 spectrometer. GC-mass
spectra were recorded with a Shimazu QP-5000 spectrometer.
Combustion analyses and mass spectra were performed in the
Instrumental Analysis Center of the Faculty of Engineering,
Osaka University. Isocyanide 2 was prepared according to the
literature.15 Diselenide and ditelluride were also prepared
according to the literature.16 Benzene and benzene-d6 were
purified by distillation from CaH2 before use. Pd(PPh3)4, Pt-
(PPh3)4, and Pd2(dba)3 were also synthesized.17,18 Preparative
TLC was carried out using Wakogel B-5F silica gel. Purifica-
tion of 1:3-adduct 5a was performed on a recycling preparative
HPLC (J apan Analytical Industry Co. Ltd., model LC-908
equipped with J AIGEL-1H and -2H columns (GPC)) using
CHCl3 as an eluent. X-ray crystal data were collected by
Rigaku AFC5R diffraction. Crystal and data collection pa-
rameters for trans-7a are summarized in the Supporting
temperature (Scheme 5). After another equivalent of
1a was added to the solution at 60 °C, the 1:2-adduct
4a formed (49% based on added 1a ) after 36 h, although
formation of Pd[(CdNAr)(SeAr)](SeAr)Ln (9a ) was not
observed during the course of reaction, which was
monitored by 31P NMR spectroscopy (Scheme 3).
The foregoing results and our previous observation6
allow us to predict the relative free energies of reaction
stages starting with 2 equiv of 1 (Y ) Se (1a ), S (1b)),
1 equiv of 2, and 1 equiv of Pd(PPh3)4 (Scheme 6, system
A). Both the oxidative addition of 1 to Pd(PPh3)4 to give
6 and the coordination of 2 to 6 to provide 7 lower the
total energy (A > B (1, 2, and 6) > C (1 and 7)).
Although the relative position between C and D (1
and 9) remains ambiguous, D is at least not so high as
to suppress the conversion of 7 into Pd[(CdNAr)p(YAr)]-
[(CdNAr)q(YAr)]Ln (p, q g 0) 10 (Scheme 7), because
1:m-adducts (m g 2) were actually afforded under
catalytic conditions in the reactions of Scheme 2.13
System E must be lower than system A in the case of Y
) S, because the Pd complex does catalyze the reaction
of 1b with 2 to afford 3b. In the case of Y ) Se,
however, the position of E relative to A is not clear but
we can at least say that the activation barrier from D
to E is high enough to prevent the reductive elimination
of 3a from 9a . Only when more than two isocyanides
(14) The low conversion would depend on the suppression effect by
free PPh3 generated as the oxidative addition proceeded. Complex 9a
was confirmed only in situ due to the facile decomposition at room
temperature. See Experimental Section.
(15) (a) Obrecht, R.; Herrmann, R.; Ugi, I. Synthesis 1985, 400. (b)
Ugi, I.; Merv, R.; Lipinski, M.; Bodesheim, F.; Rosendahl, F. In Organic
Syntheses; Wiley: New York, 1973; Vol. V, p 300.
(16) (a) Reich, H. J .; Renga, J . M.; Reich, I. L. J . Am. Chem. Soc.
1975, 97, 5434. (b) Haller, W. S.; Irgolic, K. J . J . Organomet. Chem.
1972, 38, 97.
(17) (a) Coulson, D. R. Inorg. Synth. 1972, 13, 121. (b) Ugo, R.;
Cariati, F.; Monica, G. L. Inorg. Synth. 1968, 11, 105.
(18) Ukai, T.; Kawazura, H.; Ishii, Y. J . Organomet. Chem. 1974,
65, 253.
(12) Authentic 8a was synthesized and characterized by the reaction
of Pd2(dba)3 with 2 and 1a . See Experimental Section. Rauchfuss, T.
B.; Shu, J . S.; Roundhill, D. M. Inorg. Chem. 1976, 15, 2096.
(13) Because the reaction of 3b with Pd(PPh3)4 gave 7b without
detection of 9b at room temperature, D would be higher than C and
not so high relative to E in the case of Y ) S. See ref 6.

Palladium-Catalyzed Reaction of Diselenide
Organometallics, Vol. 17, No. 5, 1998 911
Sch em e 6. P r ed icted Qu a lita tive Rea ction Coor d in a te Dia gr a m s (F r ee P P h 3s Om itted )
Sch em e 7. Com p a r ison of th e Rea ction Mech a n ism s betw een 1a a n d 1b u n d er P d -Ca ta lyzed
Rea ction s w ith 2
Information. The ORTEP drawing in Figure 1 has been shown
with 50% probability ellipsoids.
cated result with complete consumption of 2. Then the
reaction mixture was separated by PTLC (a mixture of hexane
and Et2O (9:1) as an eluent). The products obtained were 27
mg of 4a (19% based 2), 21 mg of 5a (18% based on 2), 136 mg
of 1a (80%, recovered), and a total of 38 mg of an uncharac-
terized complex oily mixture.
P a lla d iu m -Ca ta lyzed Rea ction of 1a w ith 2 (Sch em e
2). P r ep a r a tion of 4a a n d 5a . Into a dry two-necked flask
equipped with a reflux condenser and a magnetic stirring bar
were placed Pd(PPh3)4 (12 mg, 0.010 mmol), 1a (170 mg, 0.511
mmol), 2 (59 mg, 0.50 mmol), and benzene (0.5 mL) under an
argon atmosphere. After the solution was refluxed with
stirring for 14 h, the resulting catalyst was removed by
filtration through Celite and the filtrate was evaporated under
reduced pressure. The 1H NMR spectrum showed a compli-
4a : mp 202-204 °C (off-white solid); 1H NMR (270 MHz,
CDCl3, room temperature) δ 2.30 (s, 6 H), 2.42 (s, 6 H), 6.20
(d, J ) 7.8 Hz, 4 H), 7.04 (d, J ) 7.8 Hz, 4 H), 7.19 (d, J ) 7.8
Hz, 4 H), 7.66 (d, J ) 7.8 Hz, 4 H); 13C NMR (68 MHz, CDCl3,
room temperature) δ 20.96, 21.27, 119.18, 123.26, 129.42,

912 Organometallics, Vol. 17, No. 5, 1998
Kuniyasu et al.
Sch em e 8
129.87, 134.85, 138.10, 138.35, 139.58, 146.48; IR (KBr) 1630,
1611, 1504, 1436 cm-1; MS (EI) 576 m/e (M+, 2). Anal. Calcd
for C30H28N2Se2: C, 62.72; H, 4.91; N, 4.88. Found: C, 62.79;
H, 4.87; N, 4.89.
After 2 h at room temperature, only the peaks of PPh3 were
observed by 1H NMR. Then 2 (3.5 mg, 0.030 mmol) was added
into the mixture. However, the 1H NMR spectrum showed
only the peaks of 2 and PPh3, and the solid did not dissolve at
all after 2 h.
1
5a : yellow oil; H NMR (270 MHz, CDCl3, room tempera-
ture) δ 2.20 (s, 3 H), 2.26 (s, 3 H), 2.34 (s, 3 H), 2.38 (s, 3 H),
2.39 (s, 3 H), 6.66 (d, J ) 8.3 Hz, 2 H), 6.74 (d, J ) 7.8 Hz, 2
H), 6.81 (d, J ) 7.8 Hz, 2 H), 6.91 (d, J ) 8.3 Hz, 4 H), 7.01-
7.20 (m, 8 H), 7.28 (d, J ) 7.3 Hz, 2 H); 13C NMR (68 MHz,
CDCl3, room temperature) δ 20.90, 21.02, 21.02, 21.18, 21.38,
119.02, 122.23, 124.73, 128.70, 128.97, 129.72, 134.25, 134.76,
135.48, 135.91, 137.18, 139.48, 144.12, 145.74, 147.65, 157.84,
159.30, 162.16; IR (NaCl) 3023, 2922, 1622, 1503, 1455, 1196,
909, 855, 821, 803 cm-1; MS (EI) m/e 693 (M+, 2); exact mass
(M+) calcd for C38H35N3Se2 693.1161, found 693.1179.
Rea ction of 7a w ith 2 (Sch em e 5). Into a toluene-d8
solution of 7a prepared in situ (0.017 mmol from 1a , Pd(PPh3)4,
and 2) was added 2 (6.0 mg, 0.051 mmol). The 1H NMR
spectrum at room temperature showed the broad peaks of 7a
and 2. As the temperature was lowered, peak separation was
gradually observed. 1H NMR spectrum at -35 °C clearly
showed the presence of 7a and Pd(SeAr)2(CNAr)2 8a in a ratio
of 4:1. Then another one equivalent of 1a was added into the
mixture, and the sample was heated at 60 °C. After 36 h, the
formation of 49% of 4a (based on added 1a ) was confirmed;
however, no formation of 9a was observed during the course
of reaction.
The reaction using 1c in lieu of 1a was carried out under
similar reaction conditions. However, no reaction took place.
Stoich iom etr ic Rea ction s of 1a w ith P d (P P h 3)4 a n d 2
in NMR Tu bes (Sch em e 3). Into a dry Pyrex NMR tube
were added Pd(PPh3)4 (34.5 mg, 0.0299 mmol), 1a (10.2 mg,
0.0306 mmol), and benzene-d6 (0.7 mL). After the samples
were degassed under reduced pressure and purged with Ar
several times, 1,4-dioxane (2.7 mg, 0.029 mmol) was added as
an internal standard. After 2 h at room temperature, 2 (3.5
mg, 0.030 mmol) was added. Then the sample was left for 2
P r ep a r a tion of Au th en tic 8a . Into a two-necked dry 30
mL flask equipped with a stirring bar were added Pd2(dba)3‚
CHCl3 (15.5 mg, 0.0150 mmol), 2 (7.0 mg, 0.060 mmol), and
benzene (3 mL). After the mixture was stirred at room
temperature for 1 h, 1a (10.2 mg, 0.0306 mmol) was added
and the mixture was stirred for 2 h. Then 10 mL of hexane
was added into the mixture. The precipitate was separated
by filtration and washed with hexane to give 9.0 mg of 8a
(38%).
1
h, and H and 31P NMR spectra were taken. The formation of
Pd(SeAr)2(CNAr)(PPh3) (7a ) was confirmed almost quantita-
tively (cis/trans ) 8/92). Then another equivalent of 1a (10.8
mg, 0.0320 mmol) was added into the sample, and the reaction
was monitored at 60 °C; however, only the gradual decomposi-
tion of 7a was observed. Although the complete decomposition
of 7a was confirmed after 64 h, no formation of 3a was detected
at all.
8a : mp 124-130 °C (yellow solid); 1H NMR (270 MHz, C6D6)
(one isomer, stereochemistry undetermined) δ 1.71 (s, 6 H),
1.96 (s, 6 H), 6.20 (d, J ) 8.3 Hz, 4 H), 6.36 (d, J ) 7.8 Hz, 4
H), 6.69 (d, J ) 7.8 Hz, 4 H), 8.11 (d, J ) 7.8 Hz, 4 H); IR
(KBr) 2180, 1503, 1483, 1015 cm-1. Anal. Calcd for C30H28
-
N2Se2Pd: C, 52.92; H, 4.14; N, 4.11. Found: C, 53.05; H, 4.16;
N, 3.87.
P r ep a r a tion of Au th en tic 7a . Into a two-necked dry 30
mL flask equipped with a stirring bar were added Pd(PPh3)4
(57.8 mg, 0.0500 mmol), 1a (15.6 mg, 0.0468 mmol), and
benzene (5 mL). After the mixture was stirred at room
temperature for 2 h, 2 (5.7 mg, 0.049 mmol) was added and
the mixture was stirred for 30 min. Then 10 mL of hexane
was added into the mixture. The precipitate was separated
by filtration and washed by hexane to give 16.2 mg of
Pd(SeAr)2(CNAr)(PPh3) (7a ; 41%). The solid was recrystallized
from THF and hexane to give a pure trans-7a .
Oxid a t ive Ad d it ion of 4a t o P d (P P h 3)4 (Sch em e 8).
Into a dry Pyrex NMR tube were added Pd(PPh3)4 (17.5 mg,
0.0152 mmol), 4a (9.0 mg, 0.0157 mmol), and benzene-d6 (0.7
mL). The 1H NMR spectrum after 5 min showed the formation
of 10% of trans-Pd[(CdNAr)2(SeAr)](SeAr)(PPh3)2 (11a ), whose
structure was assigned by comparison of the chemical shift of
trans-Pt[(CdNAr)2(SAr)](SAr)(PPh3)2 (11b) and cis-Pt[(CdNAr)2-
(SeAr)](SeAr)(PPh3)2 (11a′). Compound 11a decomposed within
2 h at room temperature. For the spectrum data of 11b, see
ref 6.
1
7a : mp 139 °C (an yellow solid); H NMR (400 MHz, C6D6)
1
tr a n s-11a : H NMR (270 MHz, C6D6) δ 1.90 (s, 3 H), 2.31
trans isomer δ 1.71 (s, 3 H), 1.94 (s, 6 H), 6.00 (d, J ) 8.4 Hz,
2 H), 6.37 (d, J ) 8.1 Hz, 2 H), 6.65 (d, J ) 8.4 Hz, 4 H), 7.04
(m, 9 H), 7.39 (m, 6 H), 7.96 (d, J ) 7.8 Hz, 4 H); 31P NMR
(160 MHz, C6D6) trans isomer δ 28.51; 31P NMR cis isomer
(collected from a stereomixure) δ 24.87; IR (KBr) 3054, 2359,
(s, 3 H), 6.27 (d, J ) 8.4 Hz, 2 H), 6.33 (d, J ) 7.8 Hz, 2 H)
(the other peaks overlapped with the peaks of Pd(PPh3)4 and
4a ).
Syn th esis of 11a ′. Into a dry Pyrex NMR tube were added
Pt(PPh2)(CH2dCH2) (37.2 mg, 0.0498 mmol), 4a (24.8 mg,
0.0432 mmol), and benzene-d6 (0.5 mL). The sample was
degassed under reduced pressure and purged with Ar several
times. After 7 h, dry hexane was added into the solution and
the precipitated solid was collected to give 17 mg (30%) of 11a ′.
11a ′: mp 132-135 °C (yellow solid); 1H NMR (400 MHz,
C6D6) cis isomer δ 2.04 (s, 3 H), 2.09 (s, 3 H), 2.15 (s, 3 H),
2.42 (s, 3 H), 6.53 (d, J ) 7.8 Hz, 2 H), 6.74-7.24 (m, 26 H),
7.32 (d, J ) 7.8 Hz, 2 H), 7.32-7.90 (m, 12 H), 7.98 (d, J ) 7.8
Hz, 2 H), 8.17 (d, J ) 7.8 Hz, 2 H); 31P NMR (160 MHz, C6D6)
2187, 1483, 1434, 1096 cm-1
.
Anal. Calcd for C40H36-
NPPdSe2: C, 58.16; H, 4.39; N, 1.70. Found: C, 57.84; H, 4.40;
N, 1.39.
Stoich iom etr ic Rea ction s of 1c w ith P d (P P h 3)4 a n d 2
in NMR Tu be (Sch em e 4). Into a dry Pyrex NMR tube were
added Pd(PPh3)4 (34.5 mg, 0.0299 mmol), 1c (13.1 mg, 0.0299
mmol), and benzene-d6 (0.7 mL). After the sample was
degassed under reduced pressure and purged with Ar several
times, 1,4-dioxane (2.7 mg, 0.029 mmol) was added as an
internal standard. A black solid was precipitated gradually.

Palladium-Catalyzed Reaction of Diselenide
Organometallics, Vol. 17, No. 5, 1998 913
cis isomer δ 15.98 (d, J ) 19.4 Hz, J Pt-P ) 3398 Hz), 17.45 (d,
J ) 19.4 Hz, J Pt-P ) 1835 Hz); IR (KBr) 3049, 1633, 1600,
1500, 1435, 1198, 1096 cm-1. Anal. Calcd for C66H58N2Se2Pt:
C, 61.25; H, 4.52; N, 2.16. Found: C, 60.90; H, 4.81; N, 2.09.
P r ep a r a tion of P t(TeAr )2(CNAr )(P P h 3) (7c′).10 Into a
dry Pyrex NMR tube were added Pt(PPh3)4 (37.3 mg, 0.0300
mmol), 1c (13.5 mg, 0.0309 mmol), and benzene-d6 (0.7 mL).
After the samples were degassed under reduced pressure and
purged with Ar several times, 1,4-dioxane (2.5 mg, 0.028 mmol)
was added as an internal standard. After 2 h at room
temperature, 2 (3.5 mg, 0.030 mmol) was added. Then the
sample was left for 2 h, and a 1H NMR spectrum was taken.
The formation of Pt(TeAr)2(CNAr)(PPh3) 7c′ was confirmed in
94% yield (cis/trans ) 10/90). The complex 7c′ was not able
to be isolated due to facile decomposition at room temperature.
7c′: 1H NMR (400 MHz, C6D6) trans isomer δ 1.74 (s, 3 H),
1.88 (s, 6 H), 5.88 (d, J ) 8.4 Hz, 2 H), 6.36 (d, J ) 7.8 Hz, 2
H), 6.53 (d, J ) 7.8 Hz, 4 H), 7.04 (m, 9 H), 7.39 (m, 6 H), 8.06
(d, J ) 7.8 Hz, 4 H); cis isomer δ 2.07 (s, 3 H), 5.78 (d, J ) 8.4
H, 2 H), 6.82 (d, J ) 7.8 Hz, 2 H) (the other peaks overlapped
with the trans isomer).
Ack n ow led gm en t. We thank the Instrumental
Analysis Center, Faculty of Engineering, Osaka Uni-
versity, for assistance in obtaining the mass spectra
with a J EOL J MS-DX303 instrument. Financial support
of this work through a Grant-in-Aid for Scientific
Research, the Ministry of Education, and Nagase Re-
search Foundation is also acknowledged.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and data collection parameters, atomic coordinates,
isotropic thermal parameters, anisotropic displacement pa-
rameters, and bond lengths and angles (25 pages). Ordering
information is given on any current masthead page.
OM970936P