Platinum-catalyzed acrylonitrile hydrophosphination. P-C bond formation via olefin insertion into a Pt-P bond

Article abstract of DOI:10.1021/om990745h

The acrylonitrile complexes Pt(diphos)(CH₂CHCN) (diphos = dppe (1), dcpe (2); dppe = Ph₂PCH₂CH₂PPh₂, dcpe = Cy₂PCH₂CH₂PCy₂, Cy = cyclo-C₆H₁₁) are catalyst precursors and, for some substrates, resting states, during addition of P-H bonds in primary and secondary phosphines across the C=C double bond of acrylonitrile (hydrophosphination). Oxidative addition of P-H bonds to related catalyst precursors gives the phosphido hydride complexes Pt(diphos)(PRR′)(H) (diphos = dppe, R = H, R′ = Mes* (20), R = R′ = Mes (21); diphos = dcpe, R = H, R′ = Mes* (22); Mes = 2,4,6-Me₃C₆H₂, Mes* = 2,4,6-(t-Bu)₃C₆H₂). Acrylonitrile does not insert into the Pt-H bond of these hydrides to give cyanoethyl ligands; the putative products, the phosphido complexes Pt(diphos)(CH₂CH₂CN)(PRR′) (diphos = dppe, R = H, R′ = Mes* (9), R = R′ = Mes (10); diphos = dcpe, R = H, R′ = Mes* (11)) were prepared independently and found to be stable to P-C reductive elimination. Instead, catalysis appears to occur by selective insertion of acrylonitrile into the Pt-P bond to yield the alkyl hydrides Pt(diphos)[CH(CN)CH₂PRR′](H), followed by C-H reductive elimination and regeneration of 1 or 2. This insertion was observed directly in model methyl phosphido complexes M(dppe)-(Me)(PRR′) (M = Pt, R = H, R′ = Mes* (12), R = R′ = Mes (13); M = Pd, R = H, R′ = Mes* (17)), yielding M(dppe)[CH(CN)CH₂PRR′](Me), (14, 15, 18). Similarly, treatment of Pt(dcpe)-(PHMes*)(H) (22) with acrylonitrile gives Pt(dcpe)[CH(CN)CH₂PHMes*](H) (24) as a mixture of diastereomers; the isomeric Pt(dcpe)[PMes*(CH₂CH₂CN)](H) (25), which was prepared independently, was also observed during this reaction. Both 24 and 25 decompose in the presence of acrylonitrile to form Pt(dcpe)(CH₂CHCN) (2) and PHMes*(CH₂CH₂CN) (3a). The C-H reductive elimination step was modeled by studies of Pt(dcpe)[CH(Me)(CN)](H) (26). Another isomer, Pt(dcpe)[CH(Me)(CN)](PHMes*) (29), which formally results from insertion of acrylonitrile into the Pt-H bond of 22, was formed by decomposition of complex 2 during catalysis. Complex 29 is inactive in catalysis but decomposes to partially regenerate the active catalyst 2. The cyanoethyl compounds Pt(dcpe)(CH₂CH₂CN)(PHMes*) (11), trans-Pt-(PPh₃)₂(CH₂CH₂CN)(Br), and PMeS₂(CH₂CH₂CN) (23) were structurally characterized by X-ray crystallography.

Full text of DOI:10.1021/om990745h

Organometallics 1999, 18, 5381-5394
5381
P la tin u m -Ca ta lyzed Acr ylon itr ile Hyd r op h osp h in a tion .
P -C Bon d F or m a tion via Olefin In ser tion in to a P t-P
Bon d
Denyce K. Wicht, Igor V. Kourkine, Ivan Kovacik, and David S. Glueck*
6128 Burke Laboratory, Department of Chemistry, Dartmouth College,
Hanover, New Hampshire 03755
Thomas E. Concolino, Glenn P. A. Yap, Christopher D. Incarvito, and
Arnold L. Rheingold
Department of Chemistry, University of Delaware, Newark, Delaware 19716
Received September 22, 1999
The acrylonitrile complexes Pt(diphos)(CH2CHCN) (diphos ) dppe (1), dcpe (2); dppe )
Ph2PCH2CH2PPh2, dcpe ) Cy2PCH2CH2PCy2, Cy ) cyclo-C6H11) are catalyst precursors and,
for some substrates, resting states, during addition of P-H bonds in primary and secondary
phosphines across the CdC double bond of acrylonitrile (hydrophosphination). Oxidative
addition of P-H bonds to related catalyst precursors gives the phosphido hydride complexes
Pt(diphos)(PRR′)(H) (diphos ) dppe, R ) H, R′ ) Mes* (20), R ) R′ ) Mes (21); diphos )
dcpe, R ) H, R′ ) Mes* (22); Mes ) 2,4,6-Me3C6H2, Mes* ) 2,4,6-(t-Bu)3C6H2). Acrylonitrile
does not insert into the Pt-H bond of these hydrides to give cyanoethyl ligands; the putative
products, the phosphido complexes Pt(diphos)(CH2CH2CN)(PRR′) (diphos ) dppe, R ) H,
R′ ) Mes* (9), R ) R′ ) Mes (10); diphos ) dcpe, R ) H, R′ ) Mes* (11)) were prepared
independently and found to be stable to P-C reductive elimination. Instead, catalysis appears
to occur by selective insertion of acrylonitrile into the Pt-P bond to yield the alkyl hydrides
Pt(diphos)[CH(CN)CH2PRR′](H), followed by C-H reductive elimination and regeneration
of 1 or 2. This insertion was observed directly in model methyl phosphido complexes M(dppe)-
(Me)(PRR′) (M ) Pt, R ) H, R′ ) Mes* (12), R ) R′ ) Mes (13); M ) Pd, R ) H, R′ ) Mes*
(17)), yielding M(dppe)[CH(CN)CH2PRR′](Me), (14, 15, 18). Similarly, treatment of Pt(dcpe)-
(PHMes*)(H) (22) with acrylonitrile gives Pt(dcpe)[CH(CN)CH2PHMes*](H) (24) as a mixture
of diastereomers; the isomeric Pt(dcpe)[PMes*(CH2CH2CN)](H) (25), which was prepared
independently, was also observed during this reaction. Both 24 and 25 decompose in the
presence of acrylonitrile to form Pt(dcpe)(CH2CHCN) (2) and PHMes*(CH2CH2CN) (3a ). The
C-H reductive elimination step was modeled by studies of Pt(dcpe)[CH(Me)(CN)](H) (26).
Another isomer, Pt(dcpe)[CH(Me)(CN)](PHMes*) (29), which formally results from insertion
of acrylonitrile into the Pt-H bond of 22, was formed by decomposition of complex 2 during
catalysis. Complex 29 is inactive in catalysis but decomposes to partially regenerate the
active catalyst 2. The cyanoethyl compounds Pt(dcpe)(CH2CH2CN)(PHMes*) (11), trans-Pt-
(PPh3)2(CH2CH2CN)(Br), and PMes2(CH2CH2CN) (23) were structurally characterized by
X-ray crystallography.
In tr od u ction
oxidative addition of the X-H bond to a low-valent
metal center to give a hydride complex. X-C bond
formation can then proceed (Scheme 1) either (a) by
olefin insertion into the M-H bond, followed by X-C
reductive elimination, or (b) by olefin insertion into the
M-X bond and subsequent C-H reductive elimination.
Evidence has been presented for the operation of one
or both of these mechanisms in a variety of catalytic
and model systems.3
Metal-catalyzed addition of X-H bonds to olefins is
an important industrial process for several X groups
(e.g. hydrogenation, hydrosilylation, hydroboration, hy-
drocyanation).1 Analogous catalyses for X ) N, O, P, S
are potentially useful but have been less well devel-
oped.2 A common pathway for such reactions involves
* To whom correspondence should be addressed. E-mail: David.
Glueck@Dartmouth.edu.
(1) (a) Parshall, G. W.; Ittel, S. D. Homogeneous Catalysis: the
Applications and Chemistry of Catalysis by Soluble Transition Metal
Complexes, 2nd ed.; Wiley: New York, 1992. (b) Applied Homogeneous
Catalysis with Organometallic Compounds; Cornils, B., Herrmann, W.
A., Ed.; VCH: Weinheim, Germany, 1996.
We report here a study of Pt-catalyzed addition of
P-H bonds to acrylonitrile (hydrophosphination), in-
cluding direct observation of the fundamental steps
described above. In particular, P-C bond formation via
olefin insertion into a Pt-P bond (path b) has been
characterized both in a model system and in a catalyti-
(2) For a recent review, see: Han, L.-B.; Tanaka, M. Chem. Com-
mun. 1999, 395-402.
10.1021/om990745h CCC: $18.00 © 1999 American Chemical Society
Publication on Web 12/06/1999

5382 Organometallics, Vol. 18, No. 25, 1999
Wicht et al.
Sch em e 1. Tw o P ossible P a th w a ys for
Meta l-Ca ta lyzed Ad d ition of X-H Bon d s to
Olefin sa
Sch em e 2a
a
[Pt] ) Pt(diphos). For 1 (i-ii), diphos ) dppe; for 2 (iii-
iv), diphos ) dcpe. Legend: (i) CH2CHCN, NaBH4, EtOH; (ii)
CH2CHCN; (iii) CH2CHCN, 50 °C, 1 day; (iv) CH2CHCN.
diphos ) dcpe (Cy2PCH2CH2PCy2, Cy ) cyclo-C6H11)),
prepared as shown in Scheme 2. 31P{1H} NMR data for
these and other complexes prepared in this study are
a
For convenience, only one regioisomer of the product is
shown.
1
found in Table 1, and selected IR and H NMR data are
cally active one. Comparison to literature results on
metal-catalyzed X-H additions shows how the nature
of the X group affects the individual steps in the reaction
and provides design principles for further rational
development of this important class of reactions.4
given in Table 2; see the Experimental Section for
synthetic details and additional characterization data.
We hoped that understanding the mechanism of cataly-
sis with these bidentate ligands and screening trends
in catalyst activity, selectivity, and lifetime would allow
the eventual development of Pt-catalyzed asymmetric
hydrophosphination with ligands such as Binap or
Duphos.6
Resu lts a n d Discu ssion
Hyd r op h osp h in a tion Ca ta lysis. Pringle has used
Pt-catalyzed hydrophosphination to prepare useful
ligands for homogeneous catalysis.5 His previous studies
provided the following information on the mechanism
of these reactions. (1) As substrates, activated, Michael
acceptor olefins are required. (2) Olefin complexes PtL2-
(olefin) (L ) phosphine) are the catalyst resting states.5a-e
(3) Parallel mechanisms involving both mononuclear
and dinuclear intermediates were proposed for the Pt-
catalyzed addition of PH(CH2CH2CN)2 to acrylonitrile.5b
To avoid formation of bimetallic complexes, we stud-
ied catalysis by the diphosphine complexes Pt(diphos)-
(CH2CHCN) (1, diphos ) dppe (Ph2PCH2CH2PPh2); 2,
Complexes 1 and 2 act as catalyst precursors or
catalysts for addition of the P-H bonds in the primary
phosphines PH2Ph and PH2Mes* (Mes* ) 2,4,6-(t-
Bu)3C6H2) and in the secondary phosphines PH(Ph)(R)
(R ) Mes, Ph, Cy, i-Bu, Me; Mes ) 2,4,6-Me3C6H2)
across the acrylonitrile CdC double bond to give the
phosphines PPh(CH2CH2CN)2, PH(Mes*)(CH2CH2CN)
(3a ), and P(Ph)(R)(CH2CH2CN), respectively (Scheme
3). With PH2Ph, the secondary phosphine7 PH(Ph)-
(CH2CH2CN) was observed as an intermediate, but
conversion of the bulkier PH2Mes* to the tertiary
phosphine PMes*(CH2CH2CN)2 did not occur.8
The (unoptimized) catalytic reactions are summarized
in Table 3. Hydrophosphination also occurs for most of
the phosphine substrates in the absence of catalyst, but
more slowly than in the Pt-catalyzed processes. These
reactions occur more quickly for smaller phosphines,
and in many cases, other phosphine products (Table 3)
are formed. Pringle has proposed5b that byproducts in
the PH3/CH2CHCN system are due to reaction of more
than one acrylonitrile with the starting phosphine; we
assume that the phosphines formed here are similar.
The dppe complex 1 decomposes rapidly (except for
the substrate PH2Mes*) on addition of excess phosphine,
even when excess acrylonitrile is present, to form Pt-
(3) For some recent examples and leading references, see the
following. (a) X ) N: Casalnuovo, A. L.; Calabrese, J . C.; Milstein, D.
J . Am. Chem. Soc. 1988, 110, 6738-6744. (b) X ) O: Bennett, M. A.;
J in, H.; Li, S.; Rendina, L. M.; Willis, A. C. J . Am. Chem. Soc. 1995,
117, 8335-8340. (c) X ) B: Baker, R. T.; Calabrese, J . C.; Westcott, S.
A.; Nguyen, P.; Marder, T. B. J . Am. Chem. Soc. 1993, 115, 4367-
4368. (d) X ) Si: Brookhart, M.; Grant, B. E. J . Am. Chem. Soc. 1993,
115, 2151-2156. (e) For analogous X-H additions with lanthanide
catalysts, see: Arredondo, V. M.; Tian, S.; McDonald, F. E.; Marks, T.
J . J . Am. Chem. Soc. 1999, 121, 3633-3639 and references therein.
(4) Some of these results have been communicated previously:
Wicht, D. K.; Kourkine, I. V.; Lew, B. M.; Nthenge, J . M.; Glueck, D.
S. J . Am. Chem. Soc. 1997, 119, 5039-5040.
(5) (a) Costa, E.; Pringle, P. G.; Worboys, K. Chem. Commun. 1998,
49-50. (b) Costa, E.; Pringle, P. G.; Smith, M. B.; Worboys, K. J . Chem.
Soc., Dalton Trans. 1997, 4277-4282. (c) Pringle, P. G.; Brewin, D.;
Smith, M. B.; Worboys, K. In Aqueous Organometallic Chemistry and
Catalysis; Horvath, I. T., and J oo, F., Eds.; Kluwer: Dordrecht, The
Netherlands, 1995; Vol. 5, pp 111-122. (d) Hoye, P. A. T.; Pringle, P.
G.; Smith, M. B.; Worboys, K. J . Chem. Soc., Dalton Trans. 1993, 74,
269-274. (e) Pringle, P. G.; Smith, M. B. J . Chem. Soc., Chem.
Commun. 1990, 1701-1702. (f) Harrison, K. N.; Hoye, P. A. T.; Orpen,
A. G.; Pringle, P. G.; Smith, M. B. J . Chem. Soc., Chem. Commun.
1989, 1096-1097. For related chemistry, see: (g) Han, L.-B.; Choi,
N.; Tanaka, M. Organometallics 1996, 15, 3259-3261. (h) Han, L.-B.;
Tanaka, M. J . Am. Chem. Soc. 1996, 118, 1571-1572. (i) Nagel, U.;
Rieger, B.; Bublewitz, A. J . Organomet. Chem. 1989, 370, 223-239.
(j) Han, L.-B.; Choi, N.; Tanaka, M. J . Am. Chem. Soc. 1996, 118,
7000-7001. (k) Han, L.-B.; Hua, R.; Tanaka, M. Angew. Chem., Int.
Ed. Engl. 1998, 37, 94-96. For lanthanide-catalyzed reactions, see:
(l) Giardello, M. A.; King, W. A.; Nolan, S. P.; Porchia, M.; Sishta, C.;
Marks, T. J . In Energetics of Organometallic Species; Martinho Simoes,
J . A., Ed.; Kluwer: Dordrecht, The Netherlands, 1992; pp 35-51. (m)
Groger, H.; Saida, Y.; Arai, S.; Martens, J .; Sasai, H.; Shibasaki, M.
Tetrahedron Lett. 1996, 37, 9291-9292. (n) Groger, H.; Saida, Y.; Sasai,
H.; Yamaguchi, K.; Martens, J .; Shibasaki, M. J . Am. Chem. Soc. 1998,
120, 3089-3103.
(6) Wicht, D. K.; Zhuravel, M. A.; Gregush, R. V.; Glueck, D. S.;
Guzei, I. A.; Liable-Sands, L. M.; Rheingold, A. L. Organometallics
1998, 17, 1412-1419.
(7) Vinokurova, G. M.; Nagaeva, K. K. Izv. Akad. Nauk SSSR, Ser.
Khim. 1976, 414.
(8) The new secondary phosphine PH(Mes*)(CH2CH2CN) (3a ) and
the tertiary phosphine PPh(Mes)(CH2CH2CN) (3b) were prepared
independently by base-catalyzed hydrophosphination8c (see the Ex-
perimental Section). For syntheses and spectroscopic data on cyano-
ethylphosphines, see the following. (a) PPh(CH2CH2CN)2: Mann, F.
G.; Millar, I. T. J . Chem. Soc. 1952, 4453-4457. Rauhut, M. M.;
Hechenbleikner, I.; Currier, H. A.; Schaefer, F. C.; Wystrach, V. P. J .
Am. Chem. Soc. 1959, 81, 1103-1107. (b) P(Ph)(R)(CH2CH2CN) (R )
Cy, i-Bu, Me): Wolfsberger, W. Chem. Ztg. 1990, 114, 353-354. (c)
PPh2(CH2CH2CN): Habib, M.; Trujillo, H.; Alexander, C. A.; Storhoff,
B. N. Inorg. Chem. 1985, 24, 2344-2349. For reviews of hydrophos-
phination, see: (d) Wolfsberger, W. Chem. Ztg. 1988, 112, 215-221.
(e) Wolfsberger, W. Chem. Ztg. 1988, 112, 53-68. The phosphines PPh-
(CH2CH2CN)2 (Strem) and PPh2(CH2CH2CN) (Organometallics) are
commercially available.

Pt-Catalyzed Acrylonitrile Hydrophosphination
Ta ble 1. 31P NMR Da ta for P t(d ip h os) Com p lexesa -c
no. δ(P1) (J Pt-P δ(P2) (J Pt-P
Organometallics, Vol. 18, No. 25, 1999 5383
complex
)
)
δ(P3) (J Pt-P
)
J 12
J 13
J 23
Pt(dppe)(CH2CHCN)
Pt(dcpe)(CH2CHCN)
Pt(dppe)(PHPh2)2
Pt(dppe)(CH2CH2CN)(Br)
Pt(dcpe)(CH2CH2CN)(Br)
[Pt(dppe)(CH2CH2CN)(PH2Mes*)][BF4]
[Pt(dppe)(CH2CH2CN)(PHMes2)][BF4]
Pt(dppe)(CH2CH2CN)(PHMes*)
Pt(dppe)(CH2CH2CN)(PMes2)
Pt(dppe)(CH2CH2CN)(PHMes*)
1
2
4
5
6
7
8
9
53.5 (3594)
74.1(3446)
29.2 (3581)
45.4 (4163)
66.1 (1793)
55.1 (2913)
52.4 (2803)
46.7 (1904)
44.8 (1938)
64.1 (2011)
49.1 (1769)
48.5 (1755)
48.7 (1819)
60.0
51.4 (3102)
70.8 (2963)
29.2 (3581)
44.8 (1744)
59.0 (4053)
50.0 (1615)
46.2 (1659)
46.0 (1755)
33.1 (1869)
59.8 (1787)
48.0 (2208)
48.3 (2246)
47.0 (2260)
46.3
59
47
d
-16.2 (3955)
57
-64.5 (2621)
-47.5 (2533)
-65.2 (827)
-57.6 (1201)
-83.7 (806)
-65.8 (195)
-72.2 (164)
-17.9 (277)
-72.0
386
369
124
165
132
15
18
18
12
10
11
14a
14b
15
16
17
18a
18b
19
20
21
22
24a
24b
25
26g
28
29
29a
29b
6
3
3
9
Pt(dppe)(Me)[CH(CN)CH2PHMes*] (minor isomer)
Pt(dppe)(Me)[CH(CN)CH2PHMes*] (major isomer)
Pt(dppe)(Me)[CH(CN)CH2PMes2]
[Pd(dppe)(Me)(PH2Mes*)][BF4]
12
31
24
21
278
115
20
37
Pd(dppe)(Me)(PHMes*)
40.2
49.4
49.4
39.2
39.8
39.8
-51.1
Pd(dppe)(Me)[CH(CN)CH2PHMes*]e (minor isomer)
Pd(dppe)(Me)[CH(CN)CH2PHMes*] (major isomer)
[Pt(dppe)(Me)(CH2CHCN)][OTf]
-66.9
-73.5
13
50.8 (1735)
53.0 (1995)
53.3 (2011)
80.2 (1969)
75.9 (2165)
76.1 (2190)
79.9 (1934)
76.0 (2083)
66.6 (2000)
60.0 (2004)
61.2 (2043)
60.9 (2033)
39.5 (4322)
50.8 (1773)
44.9 (1906)
68.0 (1775)
65.0 (1772)
64.9 (1758)
67.5 (1953)
63.8 (1759)
60.1 (3860)
54.2 (2031)
54.0 (2035)
52.6 (2028)
Pt(dppe)(PHMes*)(H)
-73.1 (882)
-59.0 (1212)
-89.9 (868)
-68.5 (276)
-69.7 (219)
-4.8 (1130)
115
156
115
6
5
147
Pt(dppe)(PMes2)(H)f
Pt(dcpe)(PHMes*)(H)
7
8
Pt(dcpe)[CH(CN)CH2PHMes*](H) (major isomer)
Pt(dcpe)[CH(CN)CH2PHMes*](H) (minor isomer)
Pt(dcpe)[PHMes*(CH2CH2CN)](H)
Pt(dcpe)[CH(Me)(CN)](H)
Pt(dcpe)[CH(Me)(CN)](Br)
Pt(dcpe)[CH(Me)(CN)](PHMes*)
-81.5 (broad)
-77.7 (720)
-92.0 (643)
7
112
119
114
Pt(dcpe)[CH(Me)(CN)](PHMes*) (-60 °C, major isomer)
Pt(dcpe)[CH(Me)(CN)](PHMes*) (-60 °C, minor isomer)
a
The temperature is 22 °C except where noted. Chemical shifts are in ppm (external reference 85% H3PO4), and coupling constants
are in Hz. P1 and P2 are the diphos P nuclei; P3 is trans to P1. c Solvents: C6D6 for 1, 2, 9, 10, 14, 20-22, and 24-26; CDCl3 for 5, 6,
b
d
and 19; CH2Cl2 for 7 and 8; CD2Cl2 for 11; THF-d8 for 15, 28, and 29; THF for 4, 16, and 18; toluene-d8, (-50 °C) for 17. Tetrahedral
complex: P1 and P2 ) dppe, P3 and P4 ) PHPh2. e The dppe resonances for the two isomers overlapped. J PH (PHMes*): 202 (18a ), 221
1
(18b). f Kourkine, I. V.; Sargent, M. D.; Glueck, D. S. Organometallics 1998, 17, 125-127. Data for trans-Pt(PPh3)2[CH(Me)(CN)](Br)
g
(27) in THF-d8: δ 25.9 (J Pt-P ) 3071). In CH2Cl2, a 1:1 ratio of cis and trans isomers was observed: cis, δ 20.9 (J Pt-P ) 1950), 20.3 (J Pt-P
) 4228), J PP ) 17; trans, δ 24.5 (J Pt-P ) 3052).
Ta ble 2. Selected IR a n d 1H NMR Da ta for P t(d ip h os) Com p lexesa -c
no.
IRd
2198
selected 1H NMR
3
3
1
2
2.80 (d, J HH ) 9.3, 2J Pt-H ) 68, 1H, CH2CHCN), 2.75 (d, J HH ) 4.5, 2J Pt-H ) 54,
3 3 2
1H, CH2CHCN), 2.49 (dd, J HH ) 9.3, J HH ) 4.5, J Pt-H ) 50, 1H, CH2CHCN)
3
2
3
2
2195
2.47 (apparent t, J HH ) 9.6, 9.6, J Pt-H ) 63, 1H, CH2CHCN), 2.24 (dd, J HH ) 9.6, J HH ) 5.4,
3 2
1H, CH2CHCN), 2.13 (dd, J HH ) 9.6, J HH ) 5.4, 1H, CH2CHCN)
2
5
9
2231
2400, 2230
2230
2390, 2229
2393, 2185
2179
1.63-1.39 (m, J Pt-H ) 55, Pt-CH2)
2
5.10 (d of apparent triplets, J PH ) 215, 8, 8, J Pt-H ) 64, PH)
2
10
11
14a ,b
15
1.46-1.40 (m, J Pt-H ) 50, Pt-CH2)
2
5.30 (ddd, J PH ) 211, 9, 2, J Pt-H ) 59, PH)
1
3
1
3
4.57 (ddd, J PH ) 220, J HH ) 10, 7, minor PH), 4.26 (ddd, J PH ) 222, J HH ) 11, 5, major PH)
2 3
3.31 (m, J AA′ ) 12.3, 3J AB ) 11.9, 1H, CH2PMes2), 3.25 (m, 2J AA′ ) 12.3, J A′B ) 3.9,
3
3
2
1H, CH2PMes2), 2.81 (m, J AB ) 11.9, J A′B ) 3.9, J Pt-H ) 106, CH(CN))
5.61 (ddd, J PH ) 350, 6, 4, PH2)
16
17
19
20
2407
4.83 (dm, J PH ) 203, PH)
3
3
3
2233
2372, 2053
6.47 (d, J HH ) 11, 1H, CH2), 6.23 (d, J HH ) 17, 1H, CH2), 6.03 (dd, J HH ) 17, 11, 1H, CH)
2
5.56 (d of apparent t, J PH ) 211, 8, 8, J Pt-H ) 62, PH),
2
1
-1.34 (ddd, J PH ) 188, 15, 6, J Pt-H ) 1151, Pt-H)
21e
22
24a
2033
2375, 2024
-2.13 (ddd, J PH ) 187, 13.5, 13.5, J Pt-H ) 1107, Pt-H)
1
2
2
1
5.87 (ddd, J PH ) 204, 8, 2, J Pt-H ) 58, PH), -1.47 (dd, J PH ) 182, 16, J Pt-H ) 1063, Pt-H)
1 3 2
5.62 (d of apparent t, J PH ) 228, J HH ) 9, 9, PH), -1.33 (ddd, J PH ) 185, 18, 5,
1J Pt-H ) 1106, Pt-H)
1
3
2
1
24b
25
26
27
29
4.86 (ddd, J PH ) 217, J HH ) 13, 5, PH), -1.27 (ddd, J PH ) 188, 17, 5, J Pt-H ) 1132, Pt-H)
2 1
2239, 2029
2182, 1993
2199
-2.41 (d of apparent t, J PH ) 171, 17, 17, J Pt-H ) 1006, Pt-H)
2 1
-1.30 (dd, J PH ) 191, 17, J Pt-H ) 1121, Pt-H)
3 3 3
2.02 (q, J HH ) 7, CH), 0.50 (d, J HH ) 7, J Pt-H ) 67, Me)
2
2399, 2185
5.18 (br dd, J PH ) 209, 8, J Pt-H ) 56, PH)
a
b
IR spectra (KBr pellets) are in cm-1. Additional νCN IR data (cm-1): 2222 (6), 2230 (10), 2233 (19), 2193 (28). Chemical shifts are
in ppm, and coupling constants are in Hz. 31P-decoupled spectra reported for 1, 2, 27. The temperature is 22 °C except where noted.
c Solvents: C6D6 for 1, 2, 9, 10, 15, 20-22, and 24-26; CDCl3 for 5 and 19; THF-d8 for 27 and 29; CD2Cl2 for 11, 14, and 16; toluene-d8
(-50 °C) for 17. νPH ∼2400 cm-1, νCN ∼2200 cm-1, νPt-H ∼2000 cm-1
.
e Kourkine, I. V.; Sargent, M. D.; Glueck, D. S. Organometallics
d
1998, 17, 125-127.
(dppe)2 (Scheme 3).9 With PHPh2, a small amount of Pt-
(dppe)(PHPh2)2 (4) was also observed.10 The expected
disproportionation byproduct,11 Pt(L)n(CH2CHCN)m (L
) phosphine), was not observed, but the 31P NMR peaks
due to the phosphines present were broadened, consis-
tent with exchange processes involving such Pt(0)

5384 Organometallics, Vol. 18, No. 25, 1999
Wicht et al.
Sch em e 3a
CN)(PHRR′)][BF4] (R ) H, R′ ) Mes* (7); R ) R′ ) Mes
(8)), which could be deprotonated to yield the desired
phosphido complexes Pt(dppe)(CH2CH2CN)(PRR′) (R )
H, R′ ) Mes* (9); R ) R′ ) Mes (10)).16 The dcpe
complex Pt(dcpe)(CH2CH2CN)(PHMes*) (11) was pre-
pared directly from 6 by treatment with LiPHMes*.
The structures of cyanoethyl complex 11 (as an ether
solvate, Figure 1) and its precursor trans-Pt(PPh3)2(CH2-
CH2CN)(Br) were confirmed by X-ray crystallography
(see Figures 1 and 2, Table 4, the Experimental Section,
and the Supporting Information for details). Both show
the expected square-planar structure, with some distor-
tion for 11 due to the constraints of the dcpe chelate
(bite angle 86.45(7)°). The Pt-C bond in 11 (2.258(14)
Å) is longer than that in the precursor (2.115(7) Å),
consistent with the expected trans influence of dcpe and
bromide ligands.17 The PH proton in 11 was not located,
but the Pt-PHMes* bond length of 2.390(2) Å is similar
to that previously reported for Pt(dppe)(Me)(PHMes*)
(2.378(5) Å).16
a
Legend: (i) CH2CHCN, catalytic Pt(diphos)(CH2CHCN) (1
or 2), 50 °C, THF, for R and R′, see Table 3; (ii) PHRR′,
CH2CHCN, 25 °C; (iii) excess PHPh2, 25 °C.
complexes. Such mixtures were active hydrophosphi-
nation catalysts. In contrast, dcpe complex 2 remains
unchanged during most of the catalytic reactions ex-
amined. We assume that 2 is more stable than 1 due to
increased steric protection of the metal center, as well
as the difficulty of displacing the more electron-donating
alkylphosphine in an associative reaction. However, for
PH(Ph)(Me), decomposition occurred within 1 h, and for
PH(Ph)(Cy), partial decomposition was observed after
1 day. For PH2Mes*, the catalyst slowly decomposed
over the course of 1 week; this chemistry is discussed
in more detail below. In cases where catalysts 1 and 2
remained intact, no other Pt(diphos) species were
observed by 31P NMR during the reaction.
Cya n oeth yl Com p lexes. As mentioned in the In-
troduction, formation of a cyanoethyl group by insertion
of acrylonitrile into a Pt-H bond,12 followed by P-C
reductive elimination,13 is a plausible mechanism (path
a, Scheme 1) for these reactions. The putative cyano-
ethyl phosphido intermediates14 were prepared as shown
in Scheme 4. Treatment of Pt(dppe)(trans-stilbene)6
with BrCH2CH2CN gave Pt(dppe)(CH2CH2CN)(Br) (5).15
The analogous dcpe complex Pt(dcpe)(CH2CH2CN)(Br)
(6) was prepared by addition of dcpe to the known trans-
Pt(PPh3)2(CH2CH2CN)(Br).15 Bromide abstraction from
5 with AgBF4 in the presence of the appropriate phos-
phine gave the cationic complexes [Pt(dppe)(CH2CH2-
The cyanoethyl phosphido compounds 9-11 are ther-
mally stable in solution and show no tendency to
decompose via P-C reductive elimination,18 which
suggests that path a in Scheme 1 is not the mechanism
of catalysis. Consistent with this conclusion, complexes
9 and 11 did not catalyze the reaction of PH2Mes* and
acrylonitrile. Instead, complex 11 decomposed slowly
under catalytic conditions to give a trace of the second-
ary phosphine PH(Mes*)(CH2CH2CN) (3a ) and, after
several days, a small amount of Pt(dcpe)(CH2CHCN) (2).
Acr ylon it r ile In ser t ion : Mod el Syst em s. These
observations suggest that P-C bond formation might
occur via insertion of acrylonitrile into a Pt-P bond
(path b, Scheme 1). The model phosphido complexes Pt-
(dppe)(Me)(PRR′) (12, 13)16 undergo this reaction re-
giospecifically to furnish the dialkyls Pt(dppe)(Me)[CH-
(CN)CH2PRR′] (R ) H, R′ ) Mes*, 14 (2:1 mixture of
diastereomers); R ) R′ ) Mes, 15; Scheme 5). The
regiochemistry of insertion was established spectro-
scopically. For example, in 15, the Pt-CH 1H NMR
(9) Pt(dppe)2 was identified by 31P NMR and by comparison to an
authentic sample: Clark, H. C.; Kapoor, P. N.; McMahon, I. J . J .
Organomet. Chem. 1984, 265, 107-115.
(10) Complex 4 was generated independently, along with Pt(dppe)2,
by treatment of Pt(dppe)(stilbene)6 with excess PHPh2. Addition of a
large excess of PHPh2 to Pt(dppe)2 also generates a small amount of
4.
(11) For examples of related disproportionations, see: (a) Bennett,
M. A.; Chiraratvatana, C. J . Organomet. Chem. 1985, 296, 255-267.
(b) Davies, J . A.; Eagle, C. T.; Otis, D. E.; Venkataraman, U.
Organometallics 1989, 8, 1080-1088. (c) Reference 9.
(12) (a) Insertion of acrylonitrile into the Pt-H bond of trans-Pt-
(PPh2py)2(H)(Cl) (PPh2py ) 2-pyridyldiphenylphosphine) gives a cya-
noethyl group: Xie, Y.; J ames, B. R. J . Organomet. Chem. 1991, 417,
277-288. (b) However, trans-Pt(PEt3)2(p-BrC6H4)(H) does not react
with acrylonitrile in boiling n-hexane: Arnold, D. P.; Bennett, M. A.
Inorg. Chem. 1984, 23, 2110-2116.
(13) For examples of P-C reductive elimination, see: (a) Falvello,
L. R.; Fornies, J .; Fortuno, C.; Martin, A.; Martinez-Sarinena, A. P.
Organometallics 1997, 16, 5849-5856. (b) Archambault, C.; Bender,
R.; Braunstein, P.; De Cian, A.; Fischer, J . Chem. Commun. 1996,
2729-2730. (c) Shulman, P. M.; Burkhardt, E. D.; Lundquist, E. G.;
Pilato, R. S.; Geoffroy, G. L.; Rheingold, A. L. Organometallics 1987,
6, 101-109. (d) Geoffroy, G. L.; Rosenberg, S.; Shulman, P. M.; Whittle,
R. R. J . Am. Chem. Soc. 1984, 106, 1519-1521. (e) Fryzuk, M. D.; J oshi,
K.; Chadha, R. K.; Rettig, S. J . J . Am. Chem. Soc. 1991, 113, 8724-
8736. (f) Gaumont, A.-C.; Hursthouse, M. B.; Coles, S. J .; Brown, J .
M. Chem. Commun. 1999, 63-64.
(14) The PHMes* phosphido ligand was chosen, since complexes 1
and 2 decompose only slowly during Pt-catalyzed reaction of acryloni-
trile and PH2Mes*, and because this reaction in the absence of catalyst
is slow. Dimesitylphosphido complex 10 was prepared for comparison.
(15) For analogous oxidative additions of haloalkylnitriles to Pt(0),
see: Ros, R.; Renaud, J .; Roulet, R. Helv. Chim. Acta 1975, 58, 133-
139.
2
signal (C6D6) is a multiplet (δ 2.81, J Pt-H ) 106 Hz)
with inequivalent couplings (3J HH ) 11.9, 3.9 Hz) to the
diastereotopic CH2 protons, whose resonances appear
2
as multiplets at 3.31 and 3.25 ppm with J HH ) 12.3
Hz. The Pt-CH(CN) 13C NMR signal appears at δ 7.6
2
1
(d, J PC ) 90, J Pt-C ) 585 Hz), and the CN IR signal
(KBr, 2179 cm-1) is at lower frequency than usual for
nitrile groups, as previously observed for R-cyanoalkyl
complexes, consistent with the proposed regiochemistry
of insertion.19
When pure samples of 14 and 15 are redissolved, they
decompose by extrusion of acrylonitrile to regenerate
the phosphido starting materials 12 and 13 (Scheme 5).
These reactions proceed slowly at room temperature or
(16) Wicht, D. K.; Paisner, S. N.; Lew, B. M.; Glueck, D. S.; Yap, G.
P. A.; Liable-Sands, L. M.; Rheingold, A. L.; Haar, C. M.; Nolan, S. P.
Organometallics 1998, 17, 652-660.
(17) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. Rev.
1973, 10, 335-422.
(18) The analogous methyl complexes Pt(dppe)(Me)(PRR′) also do
not undergo reductive elimination.16 See the Supporting Information
for details of the thermolyses of 9-13.
(19) (a) Reger, D. L.; Garza, D. G. Organometallics 1993, 12, 554-
558. (b) Reger, D. L.; Garza, D. G.; Lebioda, L. Organometallics 1992,
11, 4285-4292. (c) Reger, D. L.; McElligott, P. J . J . Organomet. Chem.
1981, 216, C12-C14. (d) Reger, D. L. Inorg. Chem. 1975, 14, 660-
664. (e) See also ref 15.

Pt-Catalyzed Acrylonitrile Hydrophosphination
Organometallics, Vol. 18, No. 25, 1999 5385
Ta ble 3. P t-Ca ta lyzed Hyd r op h osp h in a tion of Acr ylon itr ilea
TOF
reactant
PH2Ph
PH2Mes*
PHPh2
PH(Ph)(Mes)
PH(Ph)(Cy)
PH(Ph)(i-Bu)
PH(Ph)(Me)
product
dppeb
dcpeb
no Ptc
selectivity (dppe, dcpe), %
P(Ph)(ce)2
PH(Mes*)(ce)
PPh2(ce)
P(Ph)(Mes)(ce)
P(Ph)(Cy)(ce)
P(Ph)(i-Bu)(ce)
P(Ph)(Me)(ce)
0.5 h-1
1 day-1
10 h-1
10 h-1
1 day-1
0.1 day-1
0.05 h-1
0f
68, 29d
>95
1 day-1
0.5 h-1
95, 88e
>95
1 day-1
10 day-1
10 h-1
0.5 day-1
8 day-1
8 day-1
10 day-1
0.2 day-1
2 day-1
4 day-1
82, 45g
82, 57h
88, 55i
10 h-1
a
Conditions: 10 mol % catalyst, 1.5:1 acrylonitrile to phosphine ratio (3:1 for PH2Ph), THF, 50 °C. ce ) cyanoethyl, CH2CH2CN.
Catalyst 1 decomposed immediately (see text) in all cases except for PH2Mes*. Catalyst 2 decomposed within 1 h for PH(Ph)(Me), over
7 days for PH2Mes* (see text), and slowly for PH(Ph)(Cy) (partial decomposition observed after 1 day). Product chemical shifts are as
follows (δ): PPh(ce)2, -22.3; PH(Mes*)(ce), -73.0; PPh2(ce), -15.5; PPh(Mes)(ce), -24.9; PPh(Cy)(ce) ,-10.6; PPh(i-Bu)(ce), -27.3;
PPh(Me)(ce), -33.5. b Catalytic reactions were monitored by 31P NMR (PPh3O internal standard) until the starting phosphine was consumed
(10 turnovers), except for the slow reactions of PH2Mes*, which were observed for ca. 1 half-life. The turnover frequency (TOF) is defined
as equiv of products formed/equiv of catalyst per unit time. c The control experiments were carried out under identical conditions with
the same amounts of phosphine and acrylonitrile as the catalytic ones, except that no Pt catalyst was added. TOF is defined in this case
as equiv of products formed/unit time, where the amount of starting phosphine is defined as 10 equiv, to permit direct comparison of the
rates of the control reactions with those catalyzed using 10 mol % (1 equiv) Pt complex. For example, 50% conversion of starting phosphine
to products after 1 day would be reported as a TOF of 5 day-1. The control experiments were monitored by 31P NMR for at least as long
d
as the corresponding catalytic ones, except for the very slow reaction of PH2Mes*, which was observed for 5 days. The known secondary
phosphine PH(Ph)(ce) (δ -53.1, d, J PH ) 211 Hz) was observed immediately both in the dppe system and without added Pt. For dppe,
other byproduct chemical shifts are as follows: δ -12.4, -26.2, -27.5 (ca. 1:3:4 ratio). dcpe: δ -26.2, -27.6, -30.6, -31.6, -32.9 in ca.
4:6:1:2:3 ratio. Without Pt: δ -26.2, -27.5, -59.6, -61.9 (ratio ca. 1:1:1:1). e For both catalysts and without Pt, one byproduct (δ -20.1).
g
f No reaction observed over 7 days. dppe: byproducts δ -14.9, -16.6 (ca. 1:2 ratio). dcpe: δ -14.9, -15.4, -16.6 (ca. 1:1:3 ratio); no
h
i
byproducts without Pt. dppe: byproducts δ -31.4, -33.2 (ca. 1:2 ratio; dcpe, ca. 1:3; without Pt, ca. 1:1). dppe: byproducts δ -37.4,
-38.9, -45.6 (ca. 1:1.5:trace; dcpe, ca. 1:1:trace; without Pt, similar to dppe results).
Sch em e 4a
a
[Pt] ) Pt(diphos). Legend: (i) for 5, diphos ) dppe,
BrCH2CH2CN; (ii) for 6, diphos ) dcpe, dcpe; (iii) AgBF4,
PHRR′; diphos ) dppe, R ) H, R′ ) Mes* (7), R ) R′ ) Mes
(8); (iv) NaN(SiMe3)2, for 9 and 10, diphos and R, R′ as in 7
and 8; (v) for 11, diphos ) dcpe, LiPHMes*; (vi) heating in
toluene or THF.
more quickly at 60 °C to reach an apparent equilibrium
F igu r e 1. ORTEP diagram of Pt(dcpe)(CH2CH2CN)-
with 12 and 13. Attempts to measure the equilibrium
(PHMes*)‚Et2O (11‚Et2O) with 30% thermal ellipsoids.
constants quantitatively were unsuccessful due to slow
Hydrogen atoms and the solvent molecule are omitted for
decomposition, but qualitatively, the equilibrium favors
clarity. Selected bond lengths (Å) and angles (deg): Pt(1)-
the insertion at room temperature. Coordination of the
P lone pair in 14 and 15 to the metal center20 may be
important in these â-phosphido olefin eliminations and
may also contribute to the observed Pt-P and P-P
couplings.21
P(1) ) 2.283(2), Pt(1)-P(2) ) 2.304(2), Pt(1)-P(3) ) 2.390-
(2), Pt(1)-C(3) ) 2.258(14), C(3)-C(4) ) 1.427(16), C(4)-
C(5) ) 1.579(19), N(1)-C(5) ) 1.132(13); C(3)-Pt(1)-P(1)
) 88.4(3), P(1)-Pt(1)-P(2) ) 86.45(7), C(3)-Pt(1)-P(3) )
95.1(3), P(2)-Pt(1)-P(3) ) 89.19(7).
A similar reaction of the cyanoethyl phosphido com-
plex 9 with acrylonitrile proceeded slowly and gave a
mixture of products; a 31P NMR signal at δ -80 (d, 4J PP
3
≈ 10, J Pt-P ≈160 Hz, THF) may be assigned to an
insertion product analogous to 14. However, this reac-
tion appeared to be reversible and this product could
not be isolated. Neither 9 nor these materials were
observed during catalysis, ruling out the possibility that
complex 9 is formed as an intermediate which reacts
further with acrylonitrile en route to the hydrophos-
phination product PH(Mes*)(CH2CH2CN) (3a ).
In analogous palladium chemistry (Scheme 5), the
cationic complex [Pd(dppe)(Me)(PH2Mes*)][BF4] (16)
was prepared by treatment of Pd(dppe)(Me)(Cl) with
AgBF4 and PH2Mes*. Low-temperature deprotonation
(20) For related examples in which the lone pair of a pendant amino
or phosphido ligand coordinates to the metal center, see: (a) Reference
3a. (b) Hegedus, L. S.; Akermark, B.; Zetterberg, K.; Olsson, L. F. J .
Am. Chem. Soc. 1984, 106, 7122-7126. (c) Hey-Hawkins, E.; Kurz,
S.; Sieler, J .; Baum, G. J . Organomet. Chem. 1995, 486, 229-235.
(21) A related â-aryloxy elimination from complexes containing the
Pt-CH2CH2OAr group has been reported to occur on heating, see:
Komiya, S.; Shindo, T. J . Chem. Soc., Chem. Commun. 1984, 1672-
1673. Reversible coordination of the tertiary phosphine to the metal
in a four-membered ring might occur quickly in 14 and 15 on the NMR
time scale at room temperature, but the 31P NMR spectrum of 15 was
unchanged at -75 °C.

5386 Organometallics, Vol. 18, No. 25, 1999
Wicht et al.
Sch em e 5a
a
[M] ) M(dppe); M ) Pd, Pt. Legend: (i) AgBF4, PH2Mes*;
(ii) LiN(SiMe3)2, -78 °C; (iii) dppe, -78 to 25 °C; (iv) CH2CHCN,
-78 °C (for 18); (v) CH2CHCN, R ) H, R′ ) Mes* (12, 14), R )
R′ ) Mes (13, 15).
Sch em e 6a
F igu r e 2. ORTEP diagram of [trans-Pt(PPh3)2(CH2CH2-
CN)(Br)] with 30% thermal ellipsoids and hydrogen atoms
omitted for clarity. Selected bond lengths (Å) and angles
(deg): Pt-P(1) ) 2.331(2), Pt-P(2) ) 2.336(2), Pt-C(43)
) 2.115(7), Pt-Br(1) ) 2.5630(7), C(41)-C(42) ) 1.489-
(12), C(42)-C(43) ) 1.508(11), N(1)-C(41) ) 1.167(12);
C(43)-Pt(1)-P(1) ) 90.8(2), C(43)-Pt(1)-P(2) ) 91.1(2),
P(1)-Pt(1)-Br(1) ) 90.66(5), P(2)-Pt(1)-Br(1) ) 87.36-
(4).
a
[M] ) M(dppe); M ) Pd, Pt.
Ta ble 4. Cr ysta llogr a p h ic Da ta for
tr a n s-P t(P P h 3)2(CH2CH2CN)(Br ) (A),
P t(d cp e)(CH2CH2CN)(P HMes*)‚Et2O (11‚Et2O), a n d
P Mes2CH2CH2CN (23)
temperature). Low-temperature monitoring of this reac-
tion shows that one diastereomer is initially formed
selectively but eventually becomes the minor product
on warming. A mixture of 18 and acrylonitrile decom-
poses on standing to give PH(Me)(Mes*); presumably
this occurs via extrusion of acrylonitrile and thermal
decomposition of the palladium phosphido complex.
Although such mixtures were stable at room tempera-
ture for hours, attempts to isolate 18 led to decomposi-
tion.
Related work on small-molecule insertion into metal-
heteroatom bonds24 suggests two possible limiting path-
ways for these reactions (Scheme 6). In a classical
migratory insertion process, acrylonitrile could bind to
the coordinatively unsaturated Pt center, followed by
insertion into the Pt-P bond. Bryndza has provided
evidence for such a process in the closely related
insertion of tetrafluoroethylene into the Pt-O bond of
Pt(dppe)(Me)(OMe) and in analogous CO insertions.25
A similar reaction could occur without prior binding of
the olefin. Alternatively, acrylonitrile could displace the
phosphido group to form the ionic intermediate [Pt-
(dppe)(Me)(CH2CHCN)][PRR′], followed by attack of the
phosphido anion on coordinated acrylonitrile to yield the
observed products. A related intermediate, [Ir(CO)3-
(PPh3)2][OR], was observed during carbonylation of
trans-Ir(PPh3)2(CO)(OR) by Atwood.26
A
11‚Et2O
23
formula
fw
space group
a, Å
b, Å
c, Å
â, deg
V, Å3
Z
C
39H34BrNP2Pt C53H92NOP3Pt
C21H26NP
323.40
Pna21
20.019(5)
8.843(2)
21.219(5)
853.61
P21/n
1047.28
P21/n
12.1765(2)
23.7244(3)
13.2394(2)
114.570(2)
3478.30(6)
4
11.1690(2)
19.5742(2)
24.6275(2)
99.2733(3)
5313.76(11)
4
3756(1)
8
cryst color, habit colorless rod
D(calcd), g cm-3 1.630
µ(Mo KR), cm-1 53.03
pale yellow block colorless
1.309
27.66
1.144
1.460
298
temp, K
198(2)
173(2)
T(max)/T(min)
diffractometer
1.000/0.796
Siemens
Siemens
P4
P4/CCD
P4/CCD
radiation
R(F), %a
Mo KR (λ ) 0.710 73 Å)
4.13
11.57
5.07
4.21
10.39
Rw(F2), %a
14.93
Quantity minimized ) Rw(F2) ) ∑[w(Fo2 - Fc2)2]/∑[(wFo2)2]1/2
R ) ∑∆/∑(Fo), ∆ ) |(Fo - Fc)|.
;
a
of 16 yields neutral Pd(dppe)(Me)(PHMes*) (17), which
decomposes on warming to the known secondary phos-
phine PH(Me)(Mes*)22 and the fragment Pd(dppe),
which either disproportionates to Pd(0) and Pd(dppe)2
or can be trapped by added dppe to give only Pd-
(dppe)2.23
At low temperature, 17 reacts with acrylonitrile to
yield Pd(dppe)(Me)[CH(CN)CH2PHMes*] (18) as a mix-
ture of diastereomers (2:1 ratio on warming to room
Since acrylonitrile reacts quickly with phosphido
anions, a crossover experiment is not possible. There-
fore, to test the latter possibility, the proposed inter-
mediate cation [Pt(dppe)(Me)(CH2CHCN)]+ (19) was
(22) Identified by 1H, 13C, and 31P NMR: (a) Yoshifuji, M.; Shiba-
yama, K.; Inamoto, N. Chem. Lett. 1984, 115-118. (b) Brauer, D. J .;
Bitterer, F.; Dorrenbach, F.; Hessler, G.; Stelzer, O.; Kruger, C.; Lutz,
F. Z. Naturforsch., B 1996, 51, 1183-1196.
(24) For a review, see: Bryndza, H. E.; Tam, W. Chem. Rev. 1988,
88, 1163-1188.
(25) (a) Bryndza, H. E. Organometallics 1985, 4, 406-408. (b)
Bryndza, H. E. Organometallics 1985, 4, 1686-1687. (c) For related
work implicating a migratory insertion mechanism for carbonylation
of [Pt(triphos)(OAr)]+, see: Dockter, D. W.; Fanwick, P. E.; Kubiak,
C. P. J . Am. Chem. Soc. 1996, 118, 4846-4852. (d) See also ref 3b.
(26) Rees, W. M.; Churchill, M. R.; Fettinger, J . C.; Atwood, J . D.
Organometallics 1985, 4, 2179-2185.
(23) Pd(dppe)2 was identified by 31P NMR and comparison to an
authentic sample. Further results on this and related reductive
eliminations in palladium phosphido complexes will be reported
separately: Zhuravel, M. A.; Wicht, D. K.; Nthenge, J . M.; Sweeder,
R. D.; Glueck, D. S. Manuscript in preparation.

Pt-Catalyzed Acrylonitrile Hydrophosphination
Organometallics, Vol. 18, No. 25, 1999 5387
Sch em e 7a
Sch em e 8a
a
[Pt] ) Pt(diphos). Legend: (i) diphos ) dppe, PH2Mes* (for
a
[Pt] ) Pt(dppe).
20),PHMes2(for21);(ii)PH2Mes*(for22);(iii)2PH(Mes*)(CH2CH2CN)
(for 25); (iv) 2 CH2CHCN, 20 and 25 yield 3a , 21 yields 23.
For reaction of 22 with acrylonitrile, see Scheme 9.
prepared as a triflate salt by treatment of Pt(dppe)(Me)-
(Cl) with AgOTf and an excess of acrylonitrile (Scheme
7).27 The 31P NMR spectrum of 19 (Table 1) is very
similar to that of [Pt(dppe)(Me)(NCMe)][BF4],28 which
suggests that acrylonitrile in 19 is bound to Pt via the
nitrile nitrogen, not by the CdC bond.29 Consistent with
the Pt-catalyzed hydrophosphinations studied here
proceeds via acrylonitrile insertion into the Pt-P bond
of a phosphido hydride complex.31 We next sought
evidence for the insertion step in a catalytically active
system by the synthesis of phosphido hydride complexes.
Oxidative addition of P-H bonds to Pt(dppe)(trans-
stilbene) generates Pt(dppe)(PRR′)(H) (R ) H, R′ )
Mes* (20); R ) R′ ) Mes (21); Scheme 8). Pt(dcpe)-
(PHMes*)(H) (22) was prepared by treatment of Pt-
(dcpe)H2 and/or [Pt(dcpe)H]2 with PH2Mes*.32 These
complexes were characterized spectroscopically but
could not all be isolated in analytically pure form. As
previously described, dimesitylphosphido complex 21 is
formed in an equilibrium with the precursor stilbene
complex and decomposes in solution.33 The high solubil-
ity of supermesitylphosphido complexes 20 and 22 made
them difficult to purify.
1
this conclusion, no Pt satellites are observed on the H
(Table 2) or 13C NMR signals due to coordinated
acrylonitrile, which appear at chemical shifts similar
to those in the free ligand.
Freshly prepared 19 was treated with LiPMes2‚Et2O
in THF-d8 at -78 °C;30 the 31P NMR spectrum of the
reaction mixture at -50 °C showed that a mixture of
products was formed (Scheme 7). The major species
present were Pt(dppe)(Me)(PMes2) (13) and Pt(dppe)-
(Me)[CH(CN)CH2PMes2] (15) in a ratio of approximately
2:1. A small amount of PMes2(CH2CH2CN) (23, see
below) was also observed by 31P NMR, along with
several other unidentified products.
Treatment of the dppe hydrides 20 and 21 with 2
equiv of acrylonitrile affords the acrylonitrile complex
1 and the cyanoethylphosphines PH(Mes*)(CH2CH2CN)
(3a ) and PMes2(CH2CH2CN) (23), respectively (Scheme
8). The regiochemistry of this P-C bond-forming step
was confirmed by NMR data and by the crystal struc-
ture of 23 (see Figure 3, Table 4, the Experimental
Section, and the Supporting Information). No interme-
diates were observed when these reactions were moni-
tored by NMR at low temperature in toluene-d8; for-
mation of 3a and 23 was observed above -40 and -30
°C, respectively.
These results suggest that the phosphido anion
displaces acrylonitrile from Pt to give 13 and that alkyl
complex 15 is formed by reaction between 13 and
acrylonitrile, while phosphine 23 could be formed from
reaction of lithium phosphide with acrylonitrile followed
by quenching of the resulting anion with adventitious
water. It is possible that the reaction of 13 with
acrylonitrile does proceed via displacement of the phos-
phido ligand to form the cation of 19 but that the lithium
salt of dimesitylphosphide is not a good model for the
resulting anion. Nonetheless, the simplest explanation
of the observed chemistry involves a migratory insertion
with neutral intermediates.
However, on addition of 1 equiv of acrylonitrile to dcpe
complex 22 at low temperature, the diastereomeric
Acr ylon itr ile In ser tion : Ca ta lyst System . These
model studies suggested that P-C bond formation in
(31) A closely related sequence of selective insertion of acrylonitrile
into a Pt-N, not a Pt-H, bond was reported in trans-Pt(PEt3)2(NHPh)-
(H). Notably, the isolable product trans-Pt(PEt3)2[CH(CN)CH2NHPh]-
(H) undergoes reductive elimination on heating to form 3-anilinopro-
pionitrile, while the related reaction of trans-Pt(PEt3)2(OPh)(H) with
acrylonitrile leads directly to PhOCH2CH2CN without isolation of an
intermediate. See: Cowan, R. L.; Trogler, W. C. J . Am. Chem. Soc.
1989, 111, 4750-4761.
(27) Although 19 could be isolated as a white solid in good yield,
we were unable to obtain analytically pure samples of the triflate or
BF4 salts, as indicated by peaks due to minor impurities in the 31P
NMR spectrum and by irreproducible results of IR spectra, which
showed a variety of CN stretches depending on sample history and
anion. Complex 19 decomposed over a period of days in methylene
chloride solution under nitrogen.
(32) In previous work, these hydrides were prepared by reduction
of Pt(dcpe)Cl2 under H2; the monomer could be converted to the
dinuclear complex by heating in toluene in an open system. See: (a)
Clark, H. C.; Hampden-Smith, M. J . J . Am. Chem. Soc. 1986, 108,
3829-3830. (b) Carmichael, D.; Hitchcock, P. B.; Nixon, J . F.; Pidcock,
A. J . Chem. Soc., Chem. Commun. 1988, 1554-1556. (c) Schwartz, D.
J .; Andersen, R. A. J . Am. Chem. Soc. 1995, 117, 4014-4025. We found
that treatment of Pt(dcpe)Cl2 with 2 equiv of LiBEt3H in THF or
toluene also provided Pt(dcpe)H2, sometimes contaminated with the
known cation [Pt2(dcpe)2H3]+ formed from traces of water. Surprisingly,
stirring a slurry of Pt(dcpe)H2 in petroleum ether overnight caused
almost complete conversion to [Pt(dcpe)H]2. For a similar synthesis of
[Pt(dippe)H]2 (dippe ) (i-Pr)2PCH2CH2P(i-Pr)2), see: Edelbach, B. L.;
Vicic, D. A.; Lachicotte, R. J .; J ones, W. D. Organometallics 1998, 17,
4784-4794.
(28) In CDCl3, δ 49.1 (1J Pt-P ) 1809 Hz), 38.9 (1J Pt-P ) 4370 Hz):
Appleton, T. G.; Bennett, M. A. Inorg. Chem. 1978, 17, 738-747.
(29) (a) A similar coordination mode was reported for trans-[Pt(PMe2-
Ph)2(Me)(CH2CHCN)][BF4]; see: Clark, H. C.; Ruddick, J . D.; Inorg.
Chem. 1970, 9, 1226-1229. For trans-[Pt(PEt3)2(R)(CH2CHCN)][BF4]
(R ) Me, H), see: Arnold, D. P.; Bennett, M. A. J . Organomet. Chem.
1980, 202, 107-114. (b) For a review of acrylonitrile coordination
chemistry, see: Bryan, S. J .; Huggett, P. G.; Wade, K.; Daniels, J . A.;
J ennings, J . R. Coord. Chem. Rev. 1982, 44, 149-189. (c) For a recent
report of an analogous cationic Pt diazabutadiene complex with
π-bound acrylonitrile, see: Yang, K.; Lachicotte, R. J .; Eisenberg, R.
Organometallics 1998, 17, 5102-5113. However, this complex has
recently been reformulated as N-bound. See: Albietz, P. J ., J r.; Yang,
K.; Eisenberg, R. Organometallics 1999, 18, 2747-2749.
(30) Bartlett, R. A.; Olmstead, M. M.; Power, P. P.; Sigel, G. A. Inorg.
Chem. 1987, 26, 1941-1946.
(33) Kourkine, I. V.; Sargent, M. D.; Glueck, D. S. Organometallics
1998, 17, 125-127.

5388 Organometallics, Vol. 18, No. 25, 1999
Wicht et al.
Sch em e 10a
a
L ) PPh3, [Pt] ) Pt(dcpe). Legend: (i) CH(Me)(Br)(CN);
(ii) dcpe; (iii) NaBH(OMe)3; (iv) LiPHMes*; (v) CH2CHCN; (vi)
excess PH2Mes*, excess CH2CHCN, THF, 50 °C.
F igu r e 3. ORTEP diagram of one of the two independent
but chemically equivalent molecules of PMes2(CH2CH2CN)
(23) in the asymmetric unit. Selected bond lengths (Å) and
angles (deg) for one of these: P(1)-C(26) ) 1.842(6), P(1)-
C(16) ) 1.853(5), P(1)-C(1) ) 1.835(5), C(1)-C(2) ) 1.524-
(8), C(2)-C(3) ) 1.454(8), N(1)-C(3) ) 1.119(7); C(26)-
P(1)-C(16) ) 105.7(2), C(26)-P(1)-C(1) ) 111.4(2), C(16)-
P(1)-C(1) ) 99.3(2).
Remarkably, heating a sample of isolated 25 (contain-
ing a trace of phosphine 3a ) in C6D6 at 50 °C caused it
to decompose slowly, over several days, to a mixture of
Pt(dcpe)(PHMes*)(H) (22), Pt(dcpe)(CH2CHCN) (2), and
PH(Mes*)(CH2CHCN) (3a ) in a 1:1:1 ratio (Scheme 9).
This reversible hydrophosphination might occur via
conversion of 25 to the isomeric alkyl hydrides 24a ,b,
followed by extrusion of acrylonitrile to form 22. The
liberated acrylonitrile could then react with another 1
equiv of 25 to form phosphine 3a and acrylonitrile
complex 2. This last proposed step was confirmed by
independent treatment of 25 with acrylonitrile, which
gave 2 and 3a slowly over 1 day at room temperature
(Scheme 9). No intermediates were observed in this
reaction by 31P NMR.
Sch em e 9a
The fact that reductive elimination of the C-H bond
in alkyl hydrides 24 occurs at room temperature is
surprising in view of literature reports of the stability
of the related Pt(dcpe)(Me)(H)34 and the stabilizing
effects of the CH2CN group35 on Pt(II) alkyl hydrides.
To investigate this reaction, the model hydride Pt(dcpe)-
[CH(Me)(CN)](H) (26) was prepared as shown in Scheme
10. Oxidative addition of CH(Me)(CN)(Br) to Pt(PPh3)4
gave trans-Pt(PPh3)2[CH(Me)(CN)](Br) (27), which yielded
Pt(dcpe)[CH(Me)(CN)](Br) (28) on treatment with dcpe
in CH2Cl2. Reaction of bromide 28 with NaBH(OMe)3
gave the hydride 26, which was thermally stable and
decomposed slowly at 50 °C in toluene. Addition of
PH2Mes* did not induce reductive elimination, even on
heating to 50 °C for 1 day. However, addition of 2 equiv
of acrylonitrile in toluene caused smooth formation of
acrylonitrile complex 2 at room temperature over 3 days
(Scheme 10). The analogous methyl complex Pt(dcpe)-
(Me)(H) also reacts with acrylonitrile at room temper-
ature to give 2 (Scheme 2), but this reaction is slower
and unidentified byproducts are formed. It is difficult
to compare the rate for acrylonitrile-induced decomposi-
tion of 26 directly to that for decomposition of the ana-
logous alkyl hydrides 24 due to the formation of phos-
phido hydride 25 in the latter case; qualitatively, how-
ever, the rates are similar and it appears that acryloni-
trile is required for reductive elimination to occur.
There is literature precedent for such associative
reductive elimination pathways in four-coordinate group
a
[Pt] ) Pt(dcpe). Legend: (i) CH2CHCN; (ii) 50 °C, days.
insertion products Pt(dcpe)[CH(CN)CH2PHMes*](H)
(24a , ca. 12% of the mixture, and 24b, ca. 4%) were
observed at -40 °C, along with unreacted 22 (84%,
Scheme 9). Warming to -20 °C caused further conver-
sion of 22 (64%) to 24a ,b (26, 10%); in addition, a trace
of Pt(dcpe)[PMes*(CH2CH2CN)](H) (25, see below) was
observed. Warming to room temperature caused further
reaction; after 90 min at 20 °C, the mixture consisted
of starting material 22 (32%), diastereomers 24a ,b (14
and 14%), 25 (33%), and PHMes*(CH2CH2CN) (3a , 7%).
Similar results were observed when complex 22 was
treated with acrylonitrile at room temperature (Sup-
porting Information). On further reaction (room tem-
perature, 1 day) complexes 24a ,b in such mixtures
decompose. The resulting mixture contains starting
material 22 (ca. 13% of the Pt in the mixture), Pt(dcpe)-
(CH2CHCN) (2; ca. 39%), and phosphido hydride 25 (ca.
48%), plus phosphine 3a , formed along with 2. Addition
of 2 equiv more of CH2CHCN causes, after 1 day,
complete conversion of hydrides 22 and 25 to phosphine
3a and acrylonitrile complex 2.
Complex 25 was prepared independently (Scheme 8)
from [Pt(dcpe)H]2 and PH(Mes*)(CH2CH2CN) (3a ). A
similar reaction of 3a with Pt(dcpe)H2, generated from
Pt(dcpe)Cl2 and LiBEt3H, is slower; 25 is the initial
product under these conditions, but surprisingly, Pt-
(dcpe)(PHMes*)(H) (22) and Pt(dcpe)(CH2CHCN) (2) are
also formed.
(34) Hackett, M.; Whitesides, G. M. J . Am. Chem. Soc. 1988, 110,
1449-1462.
(35) (a) Ros, R.; Michelin, R. A.; Bataillard, R.; Roulet, R. J .
Organomet. Chem. 1977, 139, 355-359. (b) Reference 11b.

Pt-Catalyzed Acrylonitrile Hydrophosphination
Organometallics, Vol. 18, No. 25, 1999 5389
Sch em e 11a
10 M(II) complexes.36 It is also possible that intramo-
lecular phosphorus coordination37 of the CH(CN)CH2-
PHMes* side chain in 24a ,b promotes reductive elimi-
nation; a similar five-coordinate species could also be
involved in acrylonitrile extrusion. Although the lack
of reaction of model complex 26 with PH2Mes* argues
against this, the chelate effect would favor the formation
of such an intermediate for 24.
a
The slow decomposition of Pt(dcpe)(CH2CHCN) (2)
during the catalytic reaction of PH2Mes* with acryloni-
trile (THF, 50 °C, ca. 1 week), mentioned briefly above,
provides additional information on the mechanism of
catalysis. This reaction yields another isomer of 24 and
25, the phosphido alkyl complex Pt(dcpe)[CH(Me)(CN)]-
(PHMes*) (29), which was confirmed by independent
synthesis via treatment of bromide 28 with LiPHMes*
(Scheme 10).38
[Pt] ) Pt(dcpe). Legend: (i) CH2CHCN; (ii) CH2CHCN,
-PH2Mes*; (iii) CH2CHCN, -PH(Mes*)(CH2CH2CN) (3a ).
Sch em e 12a
We examined the chemistry of 29 to test its role in
the catalytic hydrophosphination. Heating to 50 °C in
THF caused slow decomposition. Acrylonitrile did not
react with 29 at room temperature, in striking contrast
to the low-temperature insertion observed with the
hydride analogue Pt(dcpe)(PHMes*)(H) (22), but con-
sistent with the sluggish reaction observed for Pt(dppe)-
(CH2CH2CN)(PHMes*) (9). Heating this mixture to 50
°C for several days led to slow decomposition; a trace of
the acrylonitrile complex Pt(dcpe)(CH2CHCN) (2) was
observed by 31P NMR. Finally, when 29 (10 mol %) was
treated with PH2Mes* and acrylonitrile under the
standard catalytic conditions, the secondary phosphine
PH(Mes*)(CH2CH2CN) (3a ) was formed faster than in
the Pt-free system, but slower than if catalyst 2 was
used. Under these conditions, significant amounts of
complex 2 are formed (ca. 20% of 29 is converted to 2
after 2 days at 55 °C) and additional unidentified
products are also observed. It is not clear how phosphido
alkyl complex 29 could be formed cleanly from acryloni-
trile complex 2 in the original catalytic reaction and yet
decompose to form some of 2 under similar conditions.
Presumably these interconversions depend on the con-
centrations of PH2Mes* and acrylonitrile; since decom-
position of 29 was not clean, we did not investigate this
chemistry further.
a
[Pt] ) Pt(dppe) or Pt(dcpe).
cally favored Pt-P insertion is reversible, a competing,
but slower, insertion into the Pt-H bond could eventu-
ally lead to the formation of 29. Formation of 2 from 29
under catalysis conditions could occur by acrylonitrile
extrusion to regenerate phosphido hydride 22, which we
have shown reacts with excess acrylonitrile to form 2.
Thus, although Pt-H insertion may occur, productive
P-C bond formation appears to operate via acrylonitrile
insertion into the Pt-P bond of phosphido hydride 22.
Con clu sion s
We conclude that, in these systems, Pt-catalyzed
acrylonitrile hydrophosphination proceeds by the gen-
eral mechanism illustrated in path b of Scheme 1: P-H
oxidative addition, selective acrylonitrile insertion into
the M-P rather than the M-H bond, and acrylonitrile-
induced C-H reductive elimination of the resulting
alkyl hydride complex. As shown in Scheme 12, all the
species in this pathway, as well as in alternative path
a, have been prepared independently and isolated or
observed spectroscopically. While the product-forming
reductive elimination appears to be irreversible, both
oxidative addition and insertion steps are reversible, in
some cases. The key P-C bond-forming step was
observed both in a model system and in a catalytically
active one; the rate and reversibility of this reaction are
very sensitive to the nature of the ligands in the Pt(II)
phosphido complex. The insertion does not appear to
proceed by displacement of phosphide by the olefin;
instead, a classical insertion pathway, involving either
acrylonitrile precoordination or a concerted insertion,
is plausible.
These observations are consistent with the mecha-
nism shown in Scheme 11. Complex 29 could be formed
in the original catalysis by insertion of acrylonitrile into
the Pt-H bond of Pt(dcpe)(PHMes*)(H) (22). However,
as described above, treatment of pure 22 with acryloni-
trile leads instead to the alkyl hydride Pt(dcpe)[CH(CN)-
CH2PHMes*)](H) (24) by insertion into the Pt-P bond.
If, as seems likely from the model studies, the kineti-
(36) For examples, see: (a) Komiya, S.; Abe, Y.; Yamamoto, A.;
Yamamoto, T. Organometallics 1983, 2, 1466-1468. (b) McKinney, R.
J .; Roe, C. D. J . Am. Chem. Soc. 1985, 107, 262-264 and references
therein. (c) Kohara, T.; Yamamoto, T.; Yamamoto, A. J . Organomet.
Chem. 1980, 192, 265-274. For theoretical discussion, see: (d)
Tatsumi, K.; Nakamura, A.; Komiya, S.; Yamamoto, A.; Yamamoto,
T. J . Am. Chem. Soc. 1984, 106, 8181-8188. (e) See also ref 31 and:
Seligson, A. L.; Cowan, R. L.; Trogler, W. C. Inorg. Chem. 1991, 30,
3371-3381.
These observations provide valuable information on
fundamental mechanistic steps in hydrophosphination
and, by analogy, in other metal-catalyzed additions of
X-H bonds to olefins.
Oxid a tive Ad d ition . Catalytic hydrophosphination
is faster for smaller phosphines, probably because the
position of the equilibrium between acrylonitrile com-
(37) Four-membered metallacycles have been observed in olefin
hydroamination. For examples, see ref 20a,b.
(38) At room temperature, the 31P NMR phosphido resonance of 29
(δ -81.5) is broad and unresolved as the result of a fluxional process,
inversion at the phosphido P, which interconverts the diastereomers
of 29 on the NMR time scale. These diastereomers (7:3 ratio) were
observed under slow-exchange conditions at low temperature by 31P
NMR (Table 1) and 1H NMR. Full details will be reported separately.

5390 Organometallics, Vol. 18, No. 25, 1999
Wicht et al.
Unless otherwise noted, peaks in NMR spectra are singlets;
coupling constants are reported in Hz. Infrared spectra,
recorded as KBr pellets on a Perkin-Elmer 1600 series FTIR
instrument, are reported in cm-1. Elemental analyses were
provided by Schwarzkopf Microanalytical Laboratory, Wood-
side, NY. Unless otherwise noted, reagents were from com-
mercial suppliers. The Pt(diphos)Cl2 compounds were made
from Pt(COD)Cl2 and the diphos ligand in CH2Cl2. The
following were made by the literature methods: trans-Pt-
(PPh3)2(CH2CH2CN)(Br),15 Pt(dppe)(trans-stilbene),6 Pt(dppe)-
(Me)(PHMes*) (12) and Pt(dppe)(Me)(PMes2) (13),16 PH2-
Mes*,40 PHMes2,41 Pd(dppe)(Me)(Cl),42 Pt(dppe)(Me)(Cl),43
plexes such as 1 and 2 and phosphido hydrides such as
20-22 and 25 depends on phosphine bulk. In general,
the rate of X-H oxidative addition will depend on such
competition between the substrate and the olefin for
binding to the metal center. Using electron-rich metal
complexes to promote oxidative addition will not solve
this problem, since π-acceptor olefin ligands will then
bind more tightly to the metal. Rapid turnover may
therefore require electronic or steric destabilization of
the olefin complex and/or the use of smaller X-H
substrates. However, these approaches may favor higher
oxidation state metal species, thus slowing product-
forming reductive elimination. In this study, for ex-
ample, reaction of Pt(dppe)(PHMes*)(H) (20) with acry-
lonitrile gave the product PH(Mes*)(CH2CH2CN) (3a )
much faster than in the analogous dcpe system, where
insertion product 24 could be observed. Further, such
reductive eliminations may require additional olefin, as
suggested by the chemistry of hydrides 24 and 26.
In ser tion . Once formed by X-H oxidative addition,
metal hydride complexes MLn(H)(X) can react with
olefins either by insertion, leading to product formation
(as observed with 22), or by undesired reductive elimi-
nation (seen with 25).39 The reactions of 22 and 25 may
have different outcomes due to steric effects, but in
general the factors that control this competition, or the
one between insertion into M-X and M-H bonds, are
not well-understood. Further, it is not clear why Pt-
catalyzed hydrophosphination requires Michael-acceptor
olefin substrates, but other catalytic X-H additions will
proceed with less reactive olefins. Further mechanistic
study of the insertion step may help to answer these
questions.
1
Pt(dcpe)(Me)(H).34 31P NMR and selected H NMR and IR data
for the new metal complexes are in Tables 1 and 2; more 1H
NMR and 13C NMR data and synthetic details are given below.
For additional experimental details and complete IR data, see
the Supporting Information.
P t(d p p e)(CH2CHCN) (1). To a suspension of Pt(dppe)Cl2
(110 mg, 0.165 mmol) in 5 mL of ethanol was added acryloni-
trile (22 µL, 0.33 mmol). A solution of NaBH4 (25 mg, 0.66
mmol) in 5 mL of ethanol was added via cannula with stirring.
A new white precipitate formed, and evolution of gas was
observed. After 1 h, the precipitate was allowed to settle, and
the solution above it was removed via filter cannula. The crude
product was washed with ethanol (2 × 2 mL), water (2 × 1
mL), and ether (2 × 1 mL) and then dried under vacuum to
give a white solid (58 mg, 54%), which can be recrystallized
from THF/petroleum ether or further purified by chromatog-
raphy on silica gel with toluene eluent. Anal. Calcd for C29H27
-
NP2Pt: C, 53.87; H, 4.22; N, 2.17. Found: C, 53.61; H, 4.59;
N, 1.95. 1H NMR (C6D6): δ 7.92 (m, 2H, Ar), 7.58-7.46 (m,
6H, Ar), 7.20 (m, 2H, Ar), 6.96 (m, 10H, Ar), 2.83-2.66 (m,
2H, CH2CHCN), 2.54-2.38 (m, 1H, CH2CHCN), 2.08-1.70 (m,
4H, dppe CH2). 13C{1H} NMR (CD2Cl2): δ 135.0-134.3 (m, quat
Ar), 133.2-132.7 (m, Ar), 130.8-130.6 (m, Ar), 129.3-128.9
3
2
(m, Ar), 126.8 (dd, J PC ) 8, 3, CN), 30.3 (dd, J PC ) 44, 4,
1J Pt-C ) 246, CH2CHCN), 29.2 (dd, J PC ) 35, 15, dppe CH2),
28.7 (dd, J PC ) 34, 14, dppe CH2), 13.6 (dd, 2J PC ) 39, 7, 1J Pt-C
) 229, CH2CHCN).
Red u ctive Elim in a tion . P-C reductive elimination
is not involved in the Pt-catalyzed hydrophosphination
studied here. However, the observation of this reaction
in a model Pd complex suggests path a (Scheme 1) might
operate in related reactions with different catalysts or
substrates.
An cilla r y Liga n d . Pt-catalyzed asymmetric hydro-
phosphination will require a chiral bidentate ligand that
binds tightly to the metal and cannot be displaced as
readily as dppe. Hydrophosphination is unusual among
X-H addition reactions in that both substrate and
product phosphines are good ligands for the metal
center; thus, this requirement is not likely to be general.
P t(d cp e)(CH2CHCN) (2). A solution of 200 mg (0.32 mmol)
of Pt(dcpe)(Me)(H) in 5 mL of toluene was treated with 62 µL
(0.96 mmol) of acrylonitrile. The solution was heated at 50 °C
for 24 h. The solvent was then evaporated to give a viscous
yellow residue, which was treated with ca. 5 mL of ethanol to
precipitate a white solid that was washed with two 3 mL
portions of ethanol and finally dried in vacuo (yield 110 mg,
52%).
The following alternative synthesis gave purer material. A
white slurry of Pt(dcpe)Cl2 (200 mg, 0.29 mmol) in 20 mL of
toluene was treated with 581 µL of LiBEt3H (1 M solution in
THF, 0.58 mmol). The mixture was stirred for 30 min and then
filtered through Celite. According to 31P{1H} NMR, the yel-
lowish filtrate contained Pt(dcpe)H2 in ca. 95-98% purity (the
rest was [Pt2(dcpe)2H3]+). The filtrate was then treated with
80 µL (1.2 mmol) of CH2CHCN, which gave a colorless solution.
The solvent and the excess of acrylonitrile were removed in
vacuo, and the viscous residue was redissolved in ca. 3 mL of
toluene and passed down a short (ca. 1 cm long, 0.5 cm in
diameter) column of silica gel. The complex Pt(dcpe)(CH2-
CHCN) was eluted with ca. 10-20 mL of toluene, while the
[Pt2(dcpe)2H3]+ stayed on the column. Removal of toluene from
the eluate provided a viscous colorless residue which turned
into a white solid upon addition of ca. 3 mL of ether. This solid
Exp er im en ta l Section
Gen er a l Deta ils. Unless otherwise noted, all reactions and
manipulations were performed in dry glassware under a
nitrogen atmosphere at 20 °C in a drybox or using standard
Schlenk techniques. Petroleum ether (bp 38-53 °C), ether,
THF, and toluene were dried and distilled before use from Na/
benzophenone. CH2Cl2 was distilled from CaH2. Methanol and
ethanol were dried over Mg(OMe)2 and Mg(OEt)2, respectively.
Silica gel 60 (EM Science) was used for chromatography.
NMR spectra were recorded on Varian 300 or 500 MHz
1
spectrometers. H and 13C NMR chemical shifts are reported
relative to Me4Si and were determined by reference to the
residual 1H or 13C solvent peaks. 31P NMR chemical shifts are
reported relative to H3PO4 (85%) used as an external reference.
(40) Cowley, A. H.; Norman, N. C.; Pakulski, M. Inorg. Synth. 1990,
27, 235-240.
(41) Bartlett, R. A.; Olmstead, M. M.; Power, P. P.; Sigel, G. A. Inorg.
Chem. 1987, 26, 1941-1946.
(39) For other examples of olefin-induced X-H reductive elimina-
tion, see: (a) Glueck, D. S.; Newman Winslow, L. J .; Bergman, R. G.
Organometallics 1991, 10, 1462-1479. (b) Hauger, B.; Caulton, K. G.
J . Organomet. Chem. 1993, 450, 253-261. (c) Reference 36e.
(42) Dekker, G. P. C. M.; Elsevier: C. J .; Vrieze, K.; van Leeuwen,
P. W. N. M. Organometallics 1992, 11, 1598-1603.
(43) Clark, H. C.; J ablonski, C. R. Inorg. Chem. 1975, 14, 1518-
1526.

Pt-Catalyzed Acrylonitrile Hydrophosphination
Organometallics, Vol. 18, No. 25, 1999 5391
was separated, washed twice with 2 mL of ether and then twice
with 2 mL of petroleum ether, and finally dried in vacuo (yield
50 mg, 26%). The low yield is likely due to losses in the final
washing step. Anal. Calcd for C29H51NP2Pt: C, 51.93; H, 7.66;
of beige solid, which contained only traces of impurities.
Removing the solvent from the orange filtrate gave an ad-
ditional 266 mg of product (total yield 546 mg, 82%) which
was less pure but could also be used in subsequent reactions.
1H NMR (CDCl3): δ 7.84-7.76 (m, 4H, Ar), 7.69-7.61 (m, 4H,
Ar), 7.58-7.43 (m, 12H, Ar), 2.5-2.1 (m, 6H, dppe + CH2CN),
1
N, 2.09. Found: C, 51.78; H, 7.94; N, 2.10. H NMR (C6D6): δ
2.47 (dddd, 1 H, 3J PH ) 9.6, 3J PH ) 3.3, 3J HH ) 9.6, 3J HH ) 9.6,
2J Pt-H ) 63, CHCNCH2), 2.27-0.95 (m, 50H, CHCNCH2
+
)
1.63-1.39 (m, 2H, J Pt-H ) 55, Pt-CH2).
2
3
2
dcpe). 13C{1H} NMR (C6D6): δ 126.9 (dd, J PC ) 8, 3, J Pt-C
P t(d cp e)(CH2CH2CN)(Br ) (6). A solution of 1.0 g (1.2
mmol) of trans-[Pt(PPh3)2(CH2CH2CN)(Br)] in 80 mL of THF
was treated with a THF solution (20 mL) of dcpe (0.50 g, 1.2
mmol). The reaction mixture was stirred for 90 min and then
filtered through Celite. The filtrate was concentrated to ca.
10 mL by partial removal of THF in vacuo and cooled to -20
°C. After 7 days, the resulting white solid was separated from
the mother liquor, washed twice with cold THF (5 mL), and
finally dried in vacuo (yield 0.60 g, 68%). Anal. Calcd for
2
58, CN), 35.7-35.1 (m, Cy CH), 35.6 (dd, J PC ) 24, 4, CH2-
CHCN), 30.1-26.1 (m, Cy CH2), 24.5 (dd, J PC ) 28, 15, dcpe
CH2), 23.5 (dd, J PC ) 26, 13, dcpe CH2), 10.4 (dd, 2J PC ) 40, 7,
1J Pt-C ) 221, CH2CHCN).
Gen er a l P r oced u r e for Ca ta lytic Hyd r op h osp h in a -
tion . Catalytic reactions were carried out in NMR tubes, which
were charged with 10 mol % catalyst, 0.13 mmol of phosphine,
0.20 mmol of acrylonitrile (0.40 mmol for PH2Ph), 0.13 mmol
of PPh3O (internal standard), and ca. 0.8 mL of THF. Reaction
mixtures were heated at 50 °C and monitored by 31P NMR
spectroscopy. For all substrates, control experiments with
identical amounts of reagents, but without Pt catalyst, were
also carried out. See Table 3 for results.
C
29H52BrNP2Pt: C, 46.33; H, 6.99; N, 1.86; Br, 10.63. Found:
C, 46.91; H, 7.22; N, 1.69; Br, 10.80. 1H NMR (CDCl3): δ 2.87-
2.80 (m, 2H), 2.36-1.92 (m, 8H), 1.90-1.62 (m, 18H), 1.60-
1.10 (m, 24H). 13C{1H} NMR (CDCl3): δ 125.3 (d, J PC ) 12,
4
3J Pt-C ) 72 CN), 35.1-34.5 (m, CH), 29.4-28.6 (m, CH2), 27.2-
3
2
26.8 (m, CH2), 26.1 (broad, CH2), 20.7 (dd, J PC ) 26, 6, J Pt-C
) 84 CH2CN), 18.3 (m, CH2), 12.0 (dd, J PC ) 98, 7, J Pt-C
720, Pt-CH2).
P H(Mes*)(CH2CH2CN) (3a ). In the air, acrylonitrile (143
mg, 170 µL, 2.5 mmol) was added via microliter syringe to a
mixture of PH2Mes* (235 mg, 0.84 mmol), 10 mL of acetoni-
trile, and 1 mL of a 50% aqueous NaOH solution. The reaction
mixture was placed under slight vacuum and heated at 65 °C
for 3 h. The clear solution was cooled to room temperature,
and the product crystallized as a white solid: 220 mg, 79%
yield. Anal. Calcd for C21H34NP: C, 76.07; H, 10.36; N, 4.23.
2
1
)
P t(d p p e)(CH2CH2CN)(P HMes*) (9). This was prepared
as for the PMes2 analogue 10 (see below) in 76% yield. As for
10, the intermediate [Pt(dppe)(CH2CH2CN)(PH2Mes*)][BF4] (7)
was not isolated. Anal. Calcd for C47H58NP3Pt: C, 61.02; H,
6.33; N, 1.51. Found: C, 60.94; H, 6.76; N, 1.53. 1H NMR
(C6D6): δ 7.74-7.66 (m, 6H, Ar), 7.39-7.32 (m, 4H, Ar), 7.13-
1
Found: C, 75.80; H, 10.47; N, 4.27. H NMR (CDCl3): δ 7.35
4
1
3
3
1
(d, J PH ) 2, 2H, Ar), 4.93 (ddd, J PH ) 221, J HH ) 9, J HH
)
7.00 (m, 12H, Ar), 5.10 (d of apparent triplets, J PH ) 215,
7, 1H, PH), 2.35-2.21 (m, 1H, CH2), 2.18-2.03 (m, 1H, CH2),
1.99-1.86 (m, 1H, CH2), 1.65-1.56 (m, 1H, CH2), 1.53 (18H,
o-CMe3), 1.28 (9H, p-CMe3). 13C{1H} NMR (CDCl3): δ 155.0
2J PH ) 2J PH ) 8, 2J Pt-H ) 64, 1H, PH), 1.82 (18H, o-t-Bu), 1.80-
1.76 (m, 6H, dppe + CH2CN), 1.54 (9H, p-t-Bu), 1.50-1.30 (m,
2
2H, J Pt-H ) 55, Pt-CH2). 13C{1H} NMR (C6D6): δ 154.8 (d,
2
1
(d, J PC ) 7, quat Ar), 150.0 (quat Ar), 130.3 (d, J PC ) 28,
2J PC ) 6, quat o-Mes*), 147.8 (quat p-Mes*), 134.3 (d, J PC ) 6,
Ar), 133.8-133.4 (m, Ar), 131.8 (d, J PC ) 27, Ar), 131.2 (d, J PC
) 15, Ar), 129.3 (d, J PC ) 10, Ar), 128.9 (d, J PC ) 10, Ar), 123.5
quat Ar), 122.5 (d, 3J PC ) 4, Ar), 119.5 (d, 3J PC ) 10, CN), 38.5
4
(o-CMe3), 35.1 (p-CMe3) 33.7 (d, J PC ) 6, o-CMe3), 31.4 (p-
CMe3), 23.2 (d, J PC ) 17, CH2), 15.2 (d, J PC ) 17, CH2). 31P-
{1H} NMR (CDCl3): δ -73.0. 31P NMR (CDCl3): δ -73.0 (dd,
(d, J PC ) 12, J Pt-C ) 107, CN), 121.6 (broad, Ar), 39.1 (quat
3
CMe3), 35.4 (quat CMe3), 33.8 (d, J PC ) 8, o-CMe3), 32.3 (p-
CMe3), 29.4-28.5 (m, dppe CH2), 19.1 (broad, CH2CN), 12.9
1J PH ) 221, J PH ) 7). IR: 2392 (PH), 2240 (CN). GCMS: m/z
2
2
1
(relative intensity) 331 (25%), 330 (100%), 277 (30%).
(dd, J PC ) 87, 7, J Pt-C ) 655, Pt-CH2).
P (P h )(Mes)(CH2CH2CN) (3b). The synthesis of PH(Ph)-
(Mes) from PPhCl2 will be described elsewhere. To a solution
of PH(Ph)(Mes) (1.0 g, 4.4 mmol) and acrylonitrile (ca. 0.5 mL,
ca. 400 mg, ca. 7.5 mmol) in acetonitrile (10 mL) was added
ca. 0.5 mL of an aqueous 50% KOH solution. The flask was
heated at 50 °C for 2 h, and the resulting yellow solution was
concentrated under vacuum to give a yellow solid. Extraction
with ether separated yellow insoluble material and gave a clear
solution, which upon cooling to -25 °C gave white crystals of
the product (630 mg), which were washed with a small amount
of petroleum ether. An additional crop (227 mg) was obtained
from the mother liquor; total yield 857 mg (70%). An analytical
sample was obtained by a second recrystallization from ether.
Anal. Calcd for C18H20NP: C, 76.83; H; 7.18; N, 4.98. Found:
C, 76.55; H, 7.08; N, 4.88. 1H NMR (C6D6): δ 7.05-6.94 (m,
5H, Ph), 6.71-6.70 (m, 2H, Mes), 2.21 (6H, o-Me), 2.07 (3H,
p-Me), 2.06-1.98 (m, 2H, CH2), 1.85-1.74 (m, 2H, CH2). 13C-
{1H} NMR (C6D6): δ 146.0 (d, J PC ) 16, quat Mes), 141.0 (d,
P t(d p p e)(CH2CH2CN)(P Mes2) (10). A solution of Pt(dppe)-
(CH2CH2CN)(Br) (5; 130 mg, 0.18 mmol) in CH2Cl2 (∼5 mL)
was added to a solid mixture of AgBF4 (36 mg, 0.18 mmol)
and PHMes2 (52 mg, 0.19 mmol) to give a brown slurry. After
1 h, the reaction mixture was filtered through Celite to give a
yellow-orange solution containing [Pt(dppe)(CH2CH2CN)-
(PHMes2)][BF4] (8) (31P NMR). The solvent was removed in
vacuo, and the resulting brown oil was taken up in 3 mL of
THF and added to solid NaN(SiMe3)2 (34 mg, 0.19 mmol),
yielding a yellow-brown solution. The THF was pumped off,
and the residue was extracted with three 1 mL portions of
toluene. The orange-red toluene extract was filtered through
Celite, layered with petroleum ether, and cooled to -20 °C to
give yellow crystalline product (112 mg in two crops, 68%). A
sample was recrystallized from THF/petroleum ether for
analysis. Anal. Calcd for C47H50NP3Pt: C, 61.56; H, 5.51; N,
1.53. Found: C, 61.12; H, 5.54; N, 1.38. 1H NMR (C6D6): δ
7.57-7.43 (m, 8H, Ar), 7.10-7.07 (m, 6H, Ar), 6.96-6.94 (m,
J PC )14, quat Ar), 140.7 (d, J PC ) 1, quat Ar), 130.7 (d, J PC
)
6H, Ar), 6.69 (4H, Ar), 2.63 (12H, o-Me), 2.14 (6H, p-Me), 1.84-
2
4, Ar), 129.6 (d, J PC ) 15, Ar), 129.1 (d, J PC ) 4, Ar), 128.6 (d,
J PC ) 18, quat Ar), 127.3 (d, J PC ) 2, Ar), 119.8 (d, J PC ) 15,
CN), 23.7 (d, J PC ) 19, o-Me), 22.9 (d, J PC ) 18, CH2), 21.4
(p-Me), 15.4 (d, J PC ) 30, CH2). 31P{1H} NMR (C6D6): δ -24.9.
IR (KBr): 2918, 2249, 1604, 1433, 1376, 1025, 933, 856, 747,
699, 557.
P t(d p p e)(CH2CH2CN)(Br ) (5). An orange slurry of Pt-
(dppe)(trans-stilbene) (707 mg, 0.91 mmol) and BrCH2CH2CN
(160 mg, 1.19 mmol) in toluene (25 mL) was stirred for 2 days,
during which time the color of the suspended solid turned to
beige. The reaction mixture was filtered in air to give 280 mg
1.62 (br m, 6H, dppe + CH2CN), 1.46-1.40 (m, 2H, J Pt-H
)
50, Pt-CH2). 13C{1H} NMR (C6D6): δ 143.6 (d, J PC ) 15, quat
o-Mes), 134.9 (Ar), 134.2 (d, J PC ) 6, Ar), 133.7 (d, J PC ) 11,
Ar), 132.8, 132.2, 131.4, 130.6, 129.6-129.4 (m), 128.2 (ob-
scured by solvent), 123.1 (d, J PC ) 13, CN), 28.3-27.5 (ddd,
J PC ) 30, 15, 6, dppe CH2), 27.4-26.8 (dd, J PC ) 30, 14, dppe
CH2), 26.0 (d, J PC ) 15, o-Me), 21.3 (p-Me), 17.9 (d, J PC ) 8,
2
CH2CN), 9.9 (dd, J PC ) 93, 5, Pt-CH2, Pt satellites not
resolved).
P t(d cp e)(CH2CH2CN)(P HMes*) (11). A solution of 150 mg
(0.2 mmol) of Pt(dcpe)(CH2CH2CN)(Br) (6) in 10 mL of THF

5392 Organometallics, Vol. 18, No. 25, 1999
Wicht et al.
2
3
was treated with 10 mL of a THF solution of LiPHMes* (0.6
mmol, freshly prepared from 374 µL of 1.6 M n-BuLi in THF
and 167 mg (0.6 mmol) of PH2Mes*). The reaction mixture was
stirred at room temperature for 30 min. The solvent was then
removed in vacuo, and the yellow-orange solid residue was
extracted with ca. 20 mL of toluene. The extract was filtered
through Celite, and the solvent was removed in vacuo. Addi-
tion of an excess of ether to the fluffy residue gave a yellow
solid, which was washed three times with ca. 5 mL of ether
and finally dried in vacuo (yield 70 mg, 37%). Anal. Calcd for
6.70 (2H, Ar), 3.31 (m, J AA′ ) 12.3, J AB ) 11.9, 1H, CH2-
PMes2), 3.25 (m, 2J AA′ ) 12.3, 3J A′B ) 3.9, 1H, CH2PMes2), 2.81
3
3
2
(m, J AB ) 11.9, J A′B ) 3.9, J Pt-H ) 106, 1H, CH(CN)), 2.54
(6H, o-Me), 2.30 (6H, o-Me), 2.17 (3H, p-Me), 2.08 (3H, p-Me),
2.08-1.94 (broad m, 4H, CH2), 1.29 (dd, 3J PH ) 6.5, 6.5, 2J Pt-H
) 60, 3H, Pt-Me). 13C{1H} NMR (THF-d8): δ 144.4 (d, J PC
)
2
2
13, quat Ar), 141.1 (d, J PC ) 13, quat Ar), 138.0 (quat Ar),
136.9 (quat Ar), 136.5 (quat Ar), 135.2-134.9 (broad m, Ar),
134.7 (quat Ar), 134.5 (quat Ar), 133.9-133.7 (broad m, Ar),
132.8 (quat Ar), 132.2 (quat Ar), 131.8-131.1 (broad m, Ar),
1
C
47H82NP3Pt: C, 59.46; H, 8.72; N, 1.48. Found: C, 59.03; H,
130.6-130.3 (Ar), 129.7-129.3 (broad m, Ar), 31.6 (d, J PC
)
8.64; N, 1.42. 1H NMR (CD2Cl2): δ 7.41 (2H, Ar), 5.30 (ddd,
22, CH2PMes2), 30.9-29.5 (broad m, dppe CH2), 24.2 (d, J PC
2
2J PH ) 211, J PH ) 9, 2, J Pt-H ) 59, 1H, PH), 2.40-0.95 (br
m, 52H, dcpe + C2H4CN), 1.72 (18H, o-t-Bu), 1.41 (9H, p-t-
Bu). 13C{1H} NMR (CD2Cl2): δ 154.0 (dd, J PC ) 7, 2, o-Mes*),
146.5 (d, J PC ) 2, p-Mes*), 138.1-137.0 (br m, ipso Mes*),
124.7 (d, J PC ) 11, m-Mes*), 121.5-121.0 (m, CN), 38.8 (br,
) 11, o-Me), 23.4 (d, J PC ) 14, o-Me), 21.2 (p-Me), 21.0 (p-
3
2
2
2
1
2
Me), 7.6 (d, J PC ) 90, J Pt-C ) 585, CH(CN)), 3.4 (dd, J PC
)
1
92, 7, J Pt-C ) 600, Me) (the nitrile carbon was not resolved).
[P d (d p p e)(Me)(P H2Mes*)][BF 4] (16). To a stirred suspen-
sion of Pd(dppe)(Me)(Cl) (297 mg, 0.53 mmol) in THF (10 mL)
was added a solution of AgBF4 (104 mg, 0.53 mmol) dissolved
in CH3CN (3 mL). A white precipitate formed immediately.
PH2Mes* (164 mg, 0.59 mmol) dissolved in THF (2 mL) was
added to the reaction mixture, and the solution immediately
turned orange-brown. The reaction mixture was stirred in the
dark for 2 h and then filtered through a glass frit. The filtrate
was concentrated under vacuum to a volume of approximately
10 mL. Petroleum ether was added, and cooling to -25 °C
o-CMe3), 35.3-34.2 (m, Cy CH), 34.9 (p-CMe3), 33.1 (d, J PC
)
8, o-CMe3), 31.7 (br, p-CMe3), 30.0-26.0 (m, dcpe CH2), 24.6-
2
23.5 (m, dcpe CH2), 18.5-18.2 (m, CH2CH2CN), 7.0 (dd, J PC
) 88, 8, CH2CH2CN).
P t(d p p e)(Me)[CH(CN)CH2P HMes*] (14). Pt(dppe)(Me)-
(PHMes*) was generated in situ by treatment of Pt(dppe)(Me)-
(OMe) (245 mg, 0.38 mmol) with PH2Mes* (117 mg, 0.42 mmol)
in 20 mL of THF. The solution was concentrated under vacuum
to 10 mL. Acrylonitrile (41 mg, 50 µL, 0.77 mmol) was added
by microliter syringe, and the reaction mixture was stirred at
room temperature for 2 days, during which time the reaction
was monitored by 31P{1H} NMR. The solvent was removed
under vacuum, and the resulting pale yellow solid was
transferred to a frit, washed with petroleum ether, and dried
in vacuo to yield a 2:1 mixture of diastereomers (214 mg, 59%).
Anal. Calcd for C48H60NP3Pt: C, 61.40; H, 6.44; N, 1.49.
yielded 343 mg (73%) of orange solid. Anal. Calcd for C45H58
BF4P3Pd: C, 61.06; H, 6.61. Found: C, 60.13; H, 6.25 (results
for carbon were consistently low). H NMR (CD2Cl2): δ 7.63-
-
1
1
3
7.50 (broad m, 22H, Ar), 5.61 (ddd, J PH ) 350, J PH ) 6, 4,
2H, PH2), 2.64-2.42 (m, 4H, CH2), 1.42 (18H, o-CMe3), 1.28
(9H, p-CMe3), 0.35-0.28 (m, 3H, Me). 13C{1H} NMR (CD2Cl2):
δ 155.2 (quat Ar), 153.4 (quat Ar), 133.5-132.9 (m, Ar), 132.5
(Ar), 130.2-129.7 (m, Ar), 129.3 (quat Ar), 128.8 (quat Ar),
3
1
128.2 (quat Ar), 127.5 (quat Ar), 124.0 (d, J PC ) 9, Ar), 38.4
Found: C, 61.64; H, 6.47; N, 1.60. H NMR (500 MHz, CD2-
(o-CMe3), 35.4 (p-CMe3), 33.1 (o-CMe3), 31.0 (p-CMe3), 29.4-
Cl2; chemical shifts and relative integrals are reported for the
mixture of isomers unless specified): δ 7.89-7.84 (m, 3H, Ar),
7.79-7.75 (m, 3H, Ar), 7.68-7.57 (m, 2H, Ar), 7.54-7.42
2
28.7 (m, dppe CH2), 27.4-26.9 (m, dppe CH2), 8.2 (d, J PC
)
80, Me).
1
3
(broad m, 12H, Ar), 7.29 (2H, Ar), 4.57 (ddd, J PH ) 220, J HH
Gen er ation of P d(dppe)(Me)[CH(CN)CH2P HMes*] (18).
[Pd(dppe)(Me)(PH2Mes*)][BF4] (16; 265 mg, 0.30 mmol) in
THF (15 mL) was cooled to -78 °C in a dry ice/acetone bath.
An excess of acrylonitrile (approximately 700 µL, 10.6 mmol)
was added to the cooled solution via cannula. LiN(SiMe3)2 (50
mg, 0.30 mmol) in THF (2 mL) was also cooled to -78 °C and
transferred to the reaction mixture via cannula. The solution
was stirred at -78 °C, warmed, and monitored by 31P NMR
at room temperature. After 4 h, a 2:1 ratio of diastereomers
of 18 and a small amount of PH(Me)(Mes*) were observed.
[P t(d p p e)(Me)(CH2CHCN)][OTf] (19). To a white slurry
of Pt(dppe)(Me)(Cl) (525 mg, 0.82 mmol) and acrylonitrile (3
mL, 0.05 mol) in CH2Cl2 (20 mL) was added AgOTf (209 mg,
0.82 mmol). Immediate formation of AgCl was observed. The
reaction mixture was stirred vigorously at room temperature
overnight. The solution was filtered, and the gray-purple AgCl
residue was washed with CH2Cl2 (10 mL). The filtrates were
combined, and the solvent was removed under vacuum. The
white residue was washed with ether and dried to give 552
mg (84%) of crude product. Attempts to obtain the product
analytically pure were unsuccessful; attempted recrystalliza-
tion from CH2Cl2/petroleum ether at -25 °C gave an off-white
oil. The compound decomposes to a mixture of unknown
products in CDCl3 after 2 days. 1H NMR (CDCl3): δ 7.62-
1
3
) 10, 7, 1H, minor PH), 4.26 (ddd, J PH ) 222, J HH ) 11, 5,
3
2
1H, major PH), 2.55-2.52 (m, J HH ) 9, 8, J Pt-H ) 104, 1H,
CH(CN)), 2.42-2.18 (broad m, 4H, minor dppe CH2), 2.36-
2.06 (broad m, 4H, major dppe CH2), 2.06-1.74 (broad m, 2H,
major CH2PHMes*), 1.91-1.63 (broad m, 2H, minor CH2-
PHMes*), 1.41 (broad, 9H, p-CMe3), 1.27 (broad, 18H, o-CMe3),
3
2
0.57 (dd, J PH ) 7, 7, J Pt-H ) 66, 3H, major Me), 0.55 (dd,
3J PH ) 7, 7, J Pt-H ) 66, 3H, minor Me). 13C{1H} NMR (CD2-
2
Cl2, chemical shifts are reported for the mixture of isomers
unless specified): δ 154.6 (quat Ar), 149.0 (quat Ar), 134.4-
134.3 (m, Ar), 133.7-132.9 (m, Ar), 132.0-131.8 (broad m, Ar),
131.3-130.8 (m, Ar), 129.1 (Ar), 122.1 (Ar), 120.7-118.7 (broad
m, CN), 38.4 (p-CMe3), 35.1 (o-CMe3), 33.7 (p-CMe3), 31.8-
31.2 (m, CH2PMes*), 31.3 (o-CMe3), 30.0-28.7 (broad m, dppe
CH2), 7.14 (d, 2J PC ) 99, minor Me), 5.0 (d, 2J PC ) 95, 1J Pt-C
)
2
1
570, CH(CN)), 3.5 (d, J PC ) 90, J Pt-C ) 604, major Me).
P t (d p p e)(Me)[CH (CN)CH 2P Mes2] (15). Pt(dppe)(Me)-
(PMes2) was generated in situ by treatment of Pt(dppe)(Me)-
(OMe) (254 mg, 0.40 mmol) with PHMes2 (118 mg, 0.44 mmol).
An excess of acrylonitrile (approximately 500 µL, 7.6 mmol)
was added to the stirring solution via cannula. The reaction
mixture was stirred overnight, during which time the solution
turned from bright orange to yellow. The solvent was removed
under vacuum, and the yellow residue was washed with three
1 mL portions of petroleum ether. The solid was dissolved in
a minimal amount of THF and filtered. Petroleum ether was
added to the THF solution, and the solution was cooled to -25
°C to yield 278 mg (75%) of pale yellow Pt(dppe)(Me)[CH(CN)-
CH2PMes2]. Anal. Calcd for C48H52NP3Pt: C, 61.92; H, 5.64;
N, 1.50. Found: C, 61.99; H, 6.04; N, 1.32. 1H NMR (500 MHz,
C6D6; labeling Pt-CHB(CN)CHAHA′PMes2): δ 7.87-7.83 (m,
2H, Ar), 7.68-7.62 (m, 5H, Ar), 7.51-7.47 (m, 2H, Ar), 7.27-
7.15 (broad m, 8H, Ar), 7.08-7.02 (m, 3H, Ar), 6.73 (2H, Ar),
3
7.45 (broad m, 20H, Ar), 6.47 (d, J HH ) 11, 1H, NCCHCH2
3
trans to CN), 6.23 (d, J HH ) 17, 1H, NCCHCH2 cis to CN),
3
6.03 (dd, J HH ) 17, 11, 1H, NCCHCH2), 2.60-2.27 (m, 4H,
3
2
dppe CH2), 0.53 (dd, J PH ) 7, 3, J Pt-H ) 50, 3H, Pt-Me).
13C{1H} NMR (CDCl3): δ 144.8 (NCCHCH2), 133.3-133.1 (m,
Ar), 132.8-132.6 (m, Ar), 132.4-132.3 (m, Ar), 132.0-131.9
(m, Ar), 129.7-129.3 (m, Ar), 128.9 (quat Ar), 126.4 (quat Ar),
3
125.5 (quat Ar), 122.7 (d, J PC ) 17, CN), 105.3 (NCCHCH2),
1
2
1
30.5 (dd, J PC ) 44, J PC ) 16, dppe CH2), 24.9 (dd, J PC ) 35,
2J PC ) 5, dppe CH2), 2.8 (dd, J PC ) 79, 5, Pt-Me).
2

Pt-Catalyzed Acrylonitrile Hydrophosphination
Organometallics, Vol. 18, No. 25, 1999 5393
3
2
P t(d p p e)(H)(P HMes*) (20). To a slurry of Pt(dppe)(trans-
stilbene) (50 mg, 0.06 mmol) in THF (1 mL) was added a
solution of PH2Mes* (50 mg, 0.18 mmol) in THF (1 mL) to
afford a yellow solution. The solvent was removed, and the
residue was washed with petroleum ether (3 × 2 mL) to afford
50 mg (90% yield) of the crude yellow solid, which was
recrystallized from ether for analysis. Anal. Calcd for C44H55P3-
Pt: C, 60.61; H, 6.36. Found: C, 59.43; H, 6.43. 1H NMR
3, Ar), 120.1 (d, J PC ) 18, CN), 24.2 (d, J PC ) 18, CH2CH2-
3 1
CN), 23.3 (d, J PC ) 14, o-Me), 20.9 (p-Me), 15.2 (d, J PC ) 30,
CH2CH2CN). 31P{1H} NMR (CDCl3): δ -22.2. IR: 2242 (CN).
GCMS: M+/Z 323 (8%), 308 (100%).
Cr ysta l Str u ctu r e Deter m in a tion s. Crystal data and
data collection and refinement parameters are given in Table
4. For the platinum complexes trans-Pt(PPh3)2(CH2CH2CN)-
(Br) (A) and 11‚Et2O, the systematic absences in the diffraction
data are uniquely consistent for the reported space groups.
For phosphine 23, the systematic absences in the diffraction
data are consistent for Pna21 and Pnam (Pnma). Attempts to
solve the structure in the centric option yielded bizarre results
and were abandoned. The noncentric space group yielded
chemically reasonable and computationally stable results with
no significant correlation between independent atomic param-
eters. The structures were solved using direct methods,
completed by subsequent difference Fourier syntheses, and
refined by full-matrix least-squares procedures. Empirical
absorption corrections were applied using SADABS for A and
DIFABS for 11‚Et2O;44 semiempirical absorption corrections
were not required for 23 (µ ) 1.46 cm-1). For 23, two symmetry
independent but chemically equivalent molecules are found
in the asymmetric unit. Refinement of the absolute structure
parameter yielded 0.0(1), indicating that the true hand of the
structure had been determined. All non-hydrogen atoms were
refined with anisotropic displacement coefficients. The hydro-
gen atom on the phosphorus atom of the PHMes* ligand of
11‚Et2O could not be located from the difference map and was
ignored in the refinement, but not in the intensive properties.
All other hydrogen atoms were treated as idealized contribu-
tions. All software and sources of the scattering factors are
contained in either the SHELXTL version 5.03 or 5.10 program
libraries (G. Sheldrick, Siemens XRD, Madison, WI).
1
(C6D6): δ 7.80-6.90 (m, 22H, Ar), 5.56 (d of apparent t, J PH
) 211, 3J PH ) 8, 8, 2J Pt-H ) 62, 1H, PH), 1.80 (4H, broad, dppe),
2
1.40 (9H, p-t-Bu), 1.35 (18H, o-t-Bu), -1.34 (ddd, J PH ) 188,
15, 6, 1J Pt-H ) 1151, 1H, Pt-H). 13C{1H} NMR (C6D6): δ 153.2
(m, Ar), 146.4 (Ar), 138.2 (Ar), 134.0 (m, Ar), 133.8 (m, Ar),
130.8 (Ar), 129.2 (Ar), 129.0 (Ar), 128.9 (Ar), 127.3 (Ar), 122.0
(Ar), 39.4 (CMe3), 35.3 (broad, CMe3), 34.8 (d, J PC ) 9, o-Me),
32.3 (p-Me), 30-29 (m, CH2).
P t(d cp e)(P HMes*)(H) (22). To a slurry of Pt(dcpe)Cl2 (500
mg, 0.73 mmol) in THF (2 mL) was added LiBHEt3 (1.45 mL
of 1 M THF solution, 1.45 mmol) followed by a solution of PH2-
Mes* (213 mg, 0.76 mmol) in THF (4 mL). The resulting yellow
solution was heated at 55 °C for 2 days. The solvent was
removed, the residue was extracted with Et2O (3 × 5 mL), and
the extracts were concentrated and cooled to -20 °C to give
300 mg (43% yield) of air-sensitive yellow solid. The analytical
sample was recrystallized from Et2O. NaBH(OMe)3 can be
substituted for LiBHEt3 with similar yields. Anal. Calcd for
C44H79P3Pt: C, 59.04; H, 8.78. Found: C, 58.42; H, 9.06. 1H
1
3
NMR (C6D6): δ 7.74 (2H, Ar), 5.87 (1H, ddd, J PH ) 204, J PH
2
) 8, 2, J Pt-H ) 58, PH), 2.17 (18H, o-t-Bu), 2.08-1.00 (48H,
broad, dcpe + Cy), 1.38 (9H, p-t-Bu), -1.47 (1H, dd, J PH
2
)
1
182, 16, J Pt-H ) 1063, Pt-H). 13C{1H} NMR (C6D6): δ 152.7
(d, J PC ) 8, Ar), 145.8 (Ar), 121.9 (Ar), 39.4 (p-CMe3), 36.1-
34.7 (m, CH2 + CMe3), 32.4 (o-t-Bu), 29.8-28.9 (m, CH2), 25.0-
24.0 (m, CH). The fourth expected Ar peak is not observed.
Low -Tem p er a tu r e Rea ction of 22 w ith CH2CHCN. To
a cold (-78 °C) solution of 22 (20 mg, 0.022 mmol) in toluene-
d8 (ca. 0.4 mL) in an NMR tube was added CH2CHCN (1.5
µL, 0.022 mmol), and the tube was inserted into the cold (-40
°C) NMR probe. The reaction mixture was slowly warmed,
during which time the progress of the reaction was monitored
by 31P NMR spectroscopy. A separate experiment was carried
out on a larger scale (75 mg, 0.084 mmol of 22; 5 µL, 0.08 mmol
of acrylonitrile). In these experiments, the same products were
observed, with slightly different product ratios; therefore,
average product ratios from the two runs are described in the
text.
P t(d cp e)[P Mes*(CH2CH2CN)](H) (25). A slurry of Pt-
(dcpe)Cl2 (150 mg, 0.22 mmol) in toluene (15 mL) was treated
with 440 µL (0.44 mmol) of a 1 M THF solution of LiBHEt3.
The resulting light yellow slurry was stirred for 30 min and
then filtered through Celite. The 31P NMR spectrum of the
filtrate showed mostly Pt(dcpe)H2 and
a trace of [Pt2-
(dcpe)2H3]+. Evaporation of the solvent provided a viscous
residue. Petroleum ether (15 mL) was added, and the resulting
yellow-white slurry was stirred overnight. The solvent was
removed under vacuum to give 110 mg of a yellowish solid,
which was (by 31P{1H} NMR in toluene) mostly [Pt(dcpe)(H)]2
with traces of Pt(dcpe)H2 and [Pt2(dcpe)2H3]+. This material
was treated with PH(Mes*)(CH2CH2CN) (72 mg, 0.22 mmol)
in toluene (10 mL) and stirred for 24 h, when 31P NMR showed
that 25 had formed, with a trace of [Pt2(dcpe)2H3]+ remaining.
The solvent was removed under vacuum, and the orange-
yellow residue was extracted with petroleum ether (3 × 5 mL)
to remove the cation. The extract was filtered and concentrated
(to ca. 2 mL) to provide an orange precipitate. This was washed
with cold petroleum ether (2 × 2 mL) and finally dried in vacuo
(yield 80 mg, 39%). This compound could not be obtained in
spectroscopically pure form free from traces of phosphine 3a ,
and attempts at recrystallization from petroleum ether gave
only a very fine powder. The compound also appeared to
decompose on storage in the solid state in the glovebox. Anal.
Calcd for C47H82NP3Pt: C, 59.47; H, 8.71; N, 1.47. Found: C,
P t(d cp e)[CH(CN)CH2P HMes*](H) (24a ,b). 1H NMR (500
MHz, C6D6, dcpe signals could not be assigned for 24a and
1
24b): δ 7.60 (2H, m, Ar), 5.62 (1H, d of apparent t, J PH
)
3
228, J HH ) 9, 9, PH), 1.76 (18H, o-t-Bu), 1.35 (9H, p-t-Bu),
2
1
-1.33 (1H, ddd, J PH ) 185, 18, 5, J Pt-H ) 1106, Pt-H).
24b. 1H NMR (500 MHz, C6D6): δ 7.48 (2H, m, Ar), 4.86
1
3
(1H, ddd, J PH ) 217, J HH ) 13, 5, PH), 1.57 (18H, o-t-Bu),
1.34 (9H, p-t-Bu), -1.27 (1H, ddd, 2J PH ) 188, 17, 5, 1J Pt-H
1132, Pt-H).
)
P Mes2(CH2CH2CN) (23). In the air, acrylonitrile (204 mg,
3.8 mmol) was added to a mixture of PHMes2 (617 mg, 2.3
mmol), 10 mL of acetonitrile, and 1 mL of a 50% aqueous
sodium hydroxide solution. The mixture was cooled to -78 °C
and placed under slight vacuum. The reaction mixture was
heated at 55 °C for 3 h, during which time the product
crystallized out of solution. The clear, colorless crystals were
recrystallized from warm methanol to yield 519 mg (70%) of
PMes2(CH2CH2CN), mp 157 °C. The product was recrystallized
again from acetonitrile to yield X-ray-quality crystals. Anal.
Calcd for C21H26NP: C, 77.99; H, 8.10; N, 4.33. Found: C,
1
57.42; H, 8.84; N, 1.38. H NMR (C6D6): δ 7.60 (2H, Ar), 2.06
(18H, o-t-Bu), 2.22-0.96 (br m, 52H, dcpe + CH2CH2CN), 1.41
(9H, p-t-Bu), -2.41 (d of apparent t, 2J PH ) 171, 17, 17, 1J Pt-H
) 1006, Pt-H). 13C{1H} NMR (C6D6): δ 157.1 (dd, J PC ) 9, 3,
J Pt-C ) 34, o-Mes*), 147.0 (d, J PC ) 2, p-Mes*), 146.6 (ddd,
J PC ) 44, 7, 2, ipso-Mes*), 121.8 (d, J PC ) 5, m-Mes*), 121.4
(dd, J PC ) 14, 2, CN), 39.9 (d, J PC ) 3, o-CMe3), 36.5-35.3
(m, Cy CH), 35.1 (d, J PC ) 7, o-CMe3), 34.7 (p-CMe3), 31.7
3
4
1
4
78.11; H, 8.21; N, 4.37. H NMR (CDCl3): δ 6.78 (d, J PH ) 2,
(p-CMe3), 30.2-25.0 (dcpe CH2), 23.2 (dd, J PC ) 21, 14, CH2 of
CH2CH2CN), 18.2 (dd, J PC ) 26, 11, CH2 of CH2CH2CN).
3
2
4H, Ar), 2.79 (td, J HH ) 8, J PH ) 3, 2H, CH2CH2CN), 2.25
3
(12H, o-Me), 2.22 (6H, p-Me), 2.19 (t, J HH ) 8, 2H, CH2CH2-
CN). 13C{1H} NMR (CDCl3): δ 142.0 (d, J PC ) 14, quat Ar),
2
(44) For DIFABS, see: Walker, N.; Stuart, D. Acta Crystallogr. 1983,
A39, 158.
1
3
138.4 (quat Ar), 131.2 (d, J PC ) 20, quat Ar), 130.4 (d, J PC
)

5394 Organometallics, Vol. 18, No. 25, 1999
Wicht et al.
2
tr a n s-P t(P P h 3)2[CH(Me)(CN)](Br ) (27). Pt(PPh3)4 (0.4 g,
0.32 mmol) was dissolved in 20 mL of toluene. The orange
solution soon turned to pale yellow after treatment with 150
µL (1.73 mmol, 5.4-fold excess) of CH(Me)(Br)(CN); simulta-
neously, a white solid started to precipitate out from the
solution. The mixture was stirred at room temperature for 2
h. Then the solvent and excess of 2-bromopropionitrile were
removed in vacuo. The crude pale yellow residue was washed
four times with 5 mL portions of petroleum ether and then
dried in vacuo to give a white solid (0.26 g, 94%). A sample
for elemental analysis was recrystallized from THF. Anal.
Calcd for C39H34BrNP2Pt: C, 54.87; H, 4.02; N, 1.64; Br, 9.36.
) 23, 21, J Pt-C ) 17, CH3CHCN), 30.1-26.1 (m, dcpe CH2),
23.8 (dd, J PC ) 26, 15, dcpe CH2), 23.1 (dd, J PC ) 24, 15, dcpe
2
1
CH2), -4.1 (dd, J PC ) 83, 5, J Pt-C ) 552, Pt-CH). FAB-MS
(3-nitrobenzyl alcohol) m/z 672 (M+), 617 (Pt(dcpe)).
P t(d cp e)[CH(Me)(CN)](P HMes*) (29). A solution of 150
mg (0.2 mmol) of bromide 28 in 10 mL of THF was treated
with 10 mL of THF solution of LiPHMes* (0.6 mmol, freshly
prepared from 374 µL of 1.6 M n-BuLi in THF and 167 mg
(0.6 mmol) of PH2Mes*). The reaction mixture was stirred at
room temperature for 2 h. The solvent was then removed in
vacuo, and the yellow-orange residue was extracted with ca.
20 mL of toluene. The toluene extract was filtered through
Celite, and toluene was removed under vacuum. Addition of
an excess of petroleum ether to the viscous residue precipitated
a yellow solid. This was separated, washed three times with
ca. 5 mL of petroleum ether, and finally dried in vacuo (yield
60 mg, 32%). A sample for analysis, recrystallized from
toluene, was found to be a toluene solvate by 1H NMR and
elemental analysis. Anal. Calcd for C47H82NP3Pt‚0.75C7H8: C,
1
Found: C, 55.64; H, 4.23; N, 1.28; Br, 10.29. H NMR (THF-
d8): δ 7.88-7.77 (m, 12H, Ar), 7.46-7.35 (m, 18H, Ar), 2.02
3
3
(m, 1H, CH), 0.50 (d, 3H, J HH ) 7, J Pt-H ) 67, Me).
P t(d cp e)[CH(Me)(CN)](Br ) (28). To 15 mL of a CH2Cl2
solution of 260 mg (0.30 mmol) of 27 was added an equimolar
amount (129 mg) of dcpe dissolved in 5 mL of CH2Cl2. The
pale yellow reaction mixture was stirred at room temperature
for 1 day. Removal of the solvent in vacuo provided a yellowish
viscous residue which turned into a white solid upon addition
of ca. 5 mL of petroleum ether. The white solid was washed
three times with 5 mL portions of petroleum ether and finally
dried in vacuo (yield 200 mg, 87%). A sample for elemental
1
61.62; H, 8.73; N, 1.38. Found: C, 61.56; H, 8.73; N, 1.20. H
NMR (THF-d8, 22 °C, 500 MHz): δ 7.35 (1H, Ar), 7.25 (1H,
2
3
2
Ar), 5.18 (br dd, 1H, J PH ) 209, J PH ) 8, J Pt-H ) 56, PH),
2.67 (br m, 1H, CH), 2.50-1.00 (br m, 48H, dcpe), 1.67 (9H,
o-t-Bu), 1.66 (9H, o-t-Bu), 1.31 (9H, p-t-Bu), 0.80 (apparent t,
3H, 3J HH ) 7, 4J PH ) 7, 3J Pt-H ) 50, Me). 13C{1H} NMR (THF-
d8, 22 °C): δ 156.0 (dd, J PC ) 11, J PC ) 3, o-Mes*), 154.4 (m,
o-Mes*), 146.9 (d, J PC ) 2, p-Mes*), 136.8 (m, ipso-Mes*), 133.2
(m, CH(Me)CN), 121.5 and 121.1 (overlapping m, m-Mes*),
39.6 (br, o-CMe3), 39.1 (br, o-CMe3), 37.4-35.8 (m, Cy CH),
35.4 (br, p-CMe3), 33.9 (d, J PC ) 6, o-CMe3), 33.5 (d, J PC ) 10,
o-CMe3), 32.2 (br, p-CMe3), 31.3-27.0 (m, dcpe CH2), 20.7 (d,
3J PC ) 6, CH(Me)CN), 1.2 (dd, 2J PC ) 84, 5, CH(Me)CN). FAB-
MS (3-nitrobenzyl alcohol): m/z 948 (M+), 894 (M - CH(Me)-
(CN))+, 671 (M - PHMes*), 617 (Pt(dcpe)).
analysis was recrystallized from THF. Anal. Calcd for C29H52
-
NBrP2Pt: C, 46.33; H, 6.99; N, 1.86; Br, 10.63. Found: C,
48.26; H, 7.53; N, 1.99; Br, 10.63. Results for C and H were
consistently high; the average of four separate analyses,
including the one reported above, is as follows: C, 48.23; H,
7.57; N, 1.59; Br, 8.68. A possible explanation for these results
is cocrystallization with THF. Anal. Calcd for C29H52NBrP2-
Pt‚C4H8O: C, 48.11; H, 7.34; N, 1.70; Br, 9.70. The 31P{1H}
NMR spectrum (THF-d8), in addition to the signals in Table
1, included impurity peaks at δ 67.7 (1J Pt-P ) 2021), 58.8 (1J Pt-P
1
) 3852), 84.6, and 68.3. H NMR (THF-d8): δ 2.64-1.00 (m,
Ack n ow led gm en t. We thank the donors of the
Petroleum Research Fund, administered by the Ameri-
can Chemical Society, the Exxon Education Foundation,
DuPont, Dartmouth College, Union Carbide (Innovation
Recognition Program), and the NSF Career Program for
partial support. We also thank J ohnson-Matthey/Alfa/
Aesar for loans of Pd and Pt salts and Cytec Canada
for gifts of phosphines. The University of Delaware
acknowledges the NSF (Grant No. CHE-9628768) for
their support of the purchase of the CCD-based diffrac-
tometer. We are grateful to Dr. Paul Pringle (Bristol)
for sharing his results before publication and to Prof.
Richard Eisenberg (Rochester) for information on Pt-
acrylonitrile complexes.
52H, dcpe + CH(Me)CN). This material was pure enough for
successful preparation of complexes 26 and 29.
P t(d cp e)[CH(Me)(CN)](H) (26). A suspension of 150 mg
(0.2 mmol) of bromide 28 in 10 mL of THF was treated with a
solution of NaBH(OMe)3 (38 mg, 0.3 mmol) in 5 mL of THF.
The reaction mixture was stirred at room temperature for 1
day. The solvent was then removed in vacuo, and the pale
yellow residue was extracted with ca. 10 mL of toluene. The
toluene extract was passed down a column (ca. 0.5 cm high,
0.5 cm in diameter) of silica gel 60. The column was then
washed with an additional 5 mL of toluene. Toluene was
removed in vacuo, and addition of an excess of petroleum ether
to the viscous residue precipitated a white solid. This was
separated, washed three times with ca. 3 mL of petroleum
ether, and finally dried in vacuo (yield 80 mg, 59%). The
product was recrystallized from toluene at -30 °C for analysis.
Anal. Calcd for C29H53NP2Pt: C, 51.77; H, 7.94; N, 2.08.
Found: C, 51.92; H, 7.89; N, 2.05. 1H NMR (C6D6): δ 3.03 (m,
Su p p or tin g In for m a tion Ava ila ble: Text giving ad-
ditional experimental information and NMR and IR spectro-
scopic data and tables giving details of the crystal structure
determinations for trans-Pt(PPh3)2(CH2CH2CN)(Br), 11‚Et2O,
and 23. This material is available free of charge via the
Internet at http://pubs.acs.org.
3
3
2
1H, J HH ) 7, J PH ) 10, 7, J Pt-H ) 106, CH), 2.38 (m, 3H,
3J HH ) 7, J PH ) 6, 1, J Pt-H ) 70, Me), 2.20-0.90 (m, 48H,
4
3
2
1
dcpe), -1.30 (dd, 1H, J PH ) 191, 17, J Pt-H ) 1121, Pt-H).
13C{1H} NMR (C6D6): δ 132.6 (dd, J PC ) 6, 3, J Pt-C ) 64,
3
2
1
2
3
CN), 35.4 (br d, J PC ) 30, J Pt-C ) 35, Cy CH), 34.1 (dd, J PC
OM990745H