Organometallics
ARTICLE
cooled at À30 °C for an additional 12 h to complete crystallization.
The product was isolated by vacuum filtration, washing with cold
pentane to give [(PPh3)Pd(CH2C(CH3)2PtBu2)(OAc)]HOAc (75 mg,
0.11 mmol, 93%) as a white crystalline solid. FTIR (film, cmÀ1): 2963,
2904, 1712, 1602, 1552, 1434, 1255, 1094, 755, 697; 1H NMR (C6D6,
400 MHz): δ 14.21 (s, 1H), 7.86 (t, J = 8.8 Hz, 6H), 7.17À7.14 (m, 6H),
7.08À7.05 (m, 3H), 1.98 (s, 6H), 1.45 (d, J = 13.2 Hz, 18H), 1.22 (d, J =
12.8 Hz, 6H), 0.70 (t, J = 6.8 Hz, 2H). 31P NMR (C6D6, 162 MHz): δ
23.2 (d, J = 402 Hz), 6.0 (d, J = 402 Hz). Anal. Calcd for C34H48O4P2Pd:
C, 59.26; H, 7.02. Found: C, 58.98; H, 7.01.
General Procedure for the Reduction of Complexes Using
NaOtBu and HNBu2. A 4 mL borosilicate vial was charged with either
complex 1 (10 mg, 0.16 mmol), complex 2 (5.0 mg, 0.014 mmol Pd), or
a combination of Pd(OAc)2 (10 mg, 0.44 mmol) and PtBu3 (7.2 mg,
0.36 mmol). Sodium tert-butoxide (5 equiv) or sodium tert-butoxide
(5 equiv) and dibutylamine (5 equiv) were added followed by toluene
(1 mL). The resulting mixture was stirred for 1 h before being analyzed
by 31P NMR.
[(PPh2CH2)2Pd(CH2C(CH3)2PtBu2)(OAc)]HOAc (5). To
a
’ ASSOCIATED CONTENT
round-bottomed flask charged with complex 1 (92 mg, 0.15 mmol)
was added 1,2-bis(diphenylphosphino)ethane (60 mg, 0.15 mmol, 1.0
equiv) and THF (1 mL). The reaction was stirred at ambient tempera-
ture for 2 h. After 2 h the solvent was removed under vacuum, and the
resulting clear residue was taken up in a minimum amount of toluene,
layered with pentane, and placed at À30 °C for 12 h. The off-white
crystals were washed with pentane and dried under reduced pressure to
give [(Ph2PCH2)2Pd(CH2C(CH3)2PtBu2)(OAc)]HOAc (118 mg,
0.143 mmol, 98%) as off-white crystals. FTIR (film, cmÀ1): 3054,
2966, 2911, 1670, 1436, 1367, 1101, 748, 699, 647. 1H NMR (CD2Cl2,
400 MHz): δ 7.57À7.39 (m, 20H), 2.50À2.38 (m, 2H), 2.23À2.13 (m,
2H), 1.789 (s, 6H), 1.44 (d, J = 13.2), 1.21À1.12 (m, 20H). 31P NMR
(CD2Cl2, 162 MHz): δ 47.1 (dd, J = 360 Hz, J = 26 Hz), 41.6 (d, J =
26 Hz), À0.5 (d, J = 360 Hz). Anal. Calcd. for C42H57O4P3Pd: C, 61.13;
H, 6.96. Found: C, 61.25; H, 6.84.
S
Supporting Information. NMR spectra and X-ray crys-
b
tallographic data (in CIF format) are available free of charge via
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: stambuli@chemistry.ohio-state.edu.
’ ACKNOWLEDGMENT
This work was generously supported by The Ohio State
University. We thank Dr. Judith Gallucci (OSU) for the X-ray
crystal structure of complex 1.
Pd(PtBu2Me)2(OAc)2 (6). Di-tert-butylmethylphosphine (PtBu2Me)
(82 mg, 0.51 mmol, 2.3 equiv) was added to a stirring solution of
Pd(OAc)2 (50 mg, 0.22 mmol) in THF (1 mL) at 23 °C. The solution
was stirred for 2 h. The solvent was removed under reduced pressure, and
the resulting yellow solid was dissolved in a minimal amount of diethyl
ether, layered with pentane, and placed at À30 °C overnight to promote
crystal formation. The product was isolated by vacuum filtration, washing
with cold pentane to give Pd(PtBu2Me)2(OAc)2 (102 mg, 0.153 mmol,
69%) as a yellow crystalline solid. FTIR (film, cmÀ1): 2966, 2900, 1628,
1370, 1311, 1020, 884, 690. 1H NMR (C6D6, 400 MHz): δ 2.05 (s, 6H),
1.32 (t, J = 6.8 Hz, 32H), 0.89 (t, J = 3.2 Hz, 6H). 31P NMR (C6D6, 162
MHz): δ 28.1. Anal. Calcd for C22H48O4P2Pd: C, 48.49; H, 8.88. Found:
C, 48.45; H, 8.66.
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General Procedure for the Reduction of [(PtBu3)Pd-
(CH2C(CH3)2PtBu2)(OAc)]HOAc Using H2. In a 4 mL borosilicate
vial with a septum cap, complex 1 (10 mg, 0.16 mmol) was dissolved in
toluene-d8 (1 mL). The reaction mixture was placed under an H2
atmosphere via a balloon of H2 and allowed to purge for 5 min. After the
5 min purge was complete the reaction mixture, under a balloon of H2,
was stirred at 23 °C for 12 h. The formation of Pd(PtBu3)3 was
confirmed by 1H NMR and 31P NMR.
General Procedure for the Thermal Reduction of [(PtBu3)-
Pd(CH2C(CH3)2PtBu2)(OAc)]HOAc. In a 4 mL borosilicate vial with
septum cap, complex 1 (10 mg, 0.16 mmol) was dissolved in toluene-d8
(1 mL). The reaction mixture was stirred at 90 °C for 12 h. The
1
formation of Pd(PtBu3)3 was confirmed by H NMR and 31P NMR
spectroscopy.
General Procedure for the Amination of 2-Bromotoluene.
N,N-Dibutyl-o-toluidine was prepared according to a slightly modified
literature procedure as follows.7 To a 4 mL vial with a septum cap
containing 2-bromotoluene (120 μL, 1.00 mmol), dibutylamine (168
μL, 1.00 mmol), sodium acetate (144 mg, 1.50 mmol), 1,3,5-trimethox-
ybenzene (16.8 mg, 0.100 mmol), and catalyst (0.02 mmol) was added
toluene (1 mL). The solution was stirred for 15 min to 6 h at 23, 70, or
110 °C as specified. The reaction solution was then filtered over Celite,
and the toluene was removed under vacuum. The resulting residue was
taken up in CDCl3 and analyzed by 1H NMR.
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dx.doi.org/10.1021/om2006936 |Organometallics 2011, 30, 5038–5044