3128 Organometallics, Vol. 25, No. 13, 2006
Ca´mpora et al.
(s, CarH), 135.8 (t, JCP ) 18 Hz, Car), 137.8 (s, CarH), 143.2 (s,
Car), 168.2 (t, JCP ) 36 Hz, CarNi), 200.9 (s, CO). 31P{1H} NMR
(CD2Cl2, 20 °C, 121 MHz): δ 9.8.
the chelating diphosphine dippe, complexes 2 experience an
unusual self-addition reaction leading to the dinuclear alkoxo-
hydroxide complexes 3. This transformation can be envisaged
as a combination of hydrolysis and aldol reaction. The latter
process is not initiated by the presence of water, but it is
facilitated by the release of the monodentate phosphine ligand,
especially in the case of the volatile PMe3. It is likely that the
mechanism of this reaction is facilitated by the formation of a
dinuclear intermediate bridged through an O-enolate functional-
ity.
Synthesis of Ni(C6H4-o-C(O)CH2CH3)(Cl)(PMe2Ph)2 (1d). To
a cooled solution (-78 °C) of 1.1 g (4 mmol) of Ni(cod)2 in 50
mL of toluene was added 1.14 mL (8 mmol) of dimethylphen-
ylphosphine. The mixture was allowed to reach room temperature,
and 0.54 mL (4 mmol) of 2-chloropropiophenone was added. The
reaction mixture was heated at 45 °C for 4 h. The solvent was
removed under vacuum and the residue extracted with 10 mL of
THF. Dark red crystals of the pure product were isolated after
crystallization at -20 °C. Yield: 58%. Anal. Calcd for C25H31-
ClNiOP2: C, 59.62; H, 6.20. Found: C, 59.74; H, 6.21. IR (Nujol
mull): ν(CdO), 1644 cm-1. 1H NMR (CD2Cl2, 20 °C, 400 MHz):
δ 0.89 (bs, 6H, PMeMePh), 1.19 (t, 3H, 3JHH ) 7.2 Hz, CH2CH3),
Experimental Section
All preparations were carried out under oxygen-free nitrogen by
conventional Schlenk techniques. Solvents were rigorously dried
under nitrogen and degassed before use. Microanalyses were
performed by the Microanalytical Service of the Instituto de
Investigaciones Qu´ımicas (Sevilla, Spain). Infrared spectra were
recorded on a Bruker Vector 22 spectrometer, and NMR spectra
on Bruker DRX 300 and 400 MHz spectrometers. The 1H and 13C-
{1H} resonances of the solvent were used as the internal standard,
but the chemical shifts are reported with respect to TMS. 31P
resonances are referenced to external 85% H3PO4. The compound
2-chloropropiophenone was prepared as described previously.9b
Molecular modeling was carried out with the Spartan 04 package.16
Synthesis of Ni(C6H4-o-C(O)CH2CH3)(Cl)(PMe3)2 (1b). A 1
M solution of PMe3 in toluene (6 mL, 6 mmol) was added to a
suspension of Ni(cod)2 (825 mg, 3 mmol) in toluene (50 mL) at
-78 °C. The mixture was allowed to warm to room temperature,
and 2-chloropropiophenone (0.41 mL, 3 mmol) was added. The
resulting solution was stirred at 45 °C for 4 h, and the initial yellow
color turned dark red. The solvent was evaporated under vacuum
and the residue extracted with Et2O (20 mL). After partial
concentration of the solution and cooling to -20 °C, the product
was isolated as a red-brown solid. Yield: 75%. IR (Nujol mull):
ν(CdO), 1639 cm-1. Anal. Calcd for C15H27ClNiOP2: C, 47.48;
3
1.39 (s, 6H, PMeMePh), 2.79 (q, 2H, JHH ) 7.2 Hz, CH2CH3),
3
3
6.74 (t, 1H, JHH ) 7.4 Hz, CarH), 6.82 (t, 1H, JHH ) 7.1 Hz,
CarH), 7.20 (d, 1H, 3JHH ) 7.4 Hz, CarH), 7.26-7.35 (m, 6H, CarH),
7.44 (bs, 4H, CarH). 13C{1H} NMR (CD2Cl2, 20 °C, 75 MHz): δ
8.8 (s, CH2CH3), 11.5 (t, JCP ) 14 Hz, PMeMePh), 12.9 (t, JCP
)
13 Hz, PMeMePh), 31.4 (s, CH2CH3), 121.6 (s, CarH), 128.2 (s,
CarH), 129.2 (s, CarH), 129.4 (s, CarH), 130.1 (s, CarH), 135.9 (t,
2
JCP ) 19 Hz, Car), 138.0 (s, CarH), 142.8 (s, Car), 167.9 (t, JCP
)
36 Hz, CarNi), 203.5 (s, CO). 31P{1H} NMR (CD2Cl2, 20 °C, 121
MHz): δ -9.9 (s).
Synthesis of 2b. Potassium tert-butoxide (57 mg, 0.5 mmol) was
dissolved in 3 mL of THF and added to a cooled solution (-78
°C) of 190 mg of complex 1b (0.5 mmol) in 10 mL of THF. After
reaching room temperature, the solvent was removed under reduced
pressure, and 8 mL of a solution of PMe3 (0.1 mmol) in Et2O was
added to afford an orange solution. The solution was filtered from
a yellow precipitate of compound 3b and cooled to -20 °C to give
2b as orange crystals. Yield: 15%. Anal. Calcd for C15H26NiOP2:
C, 52.52; H, 7.64. Found: C, 52.99; H, 7.89. IR (Nujol mull): ν-
(CdC), 1614 cm-1. 1H NMR (C6D6, 20 °C, 400 MHz): δ 0.87 (d,
18H, 2JHP ) 7.7 Hz, PMe3), 2.29 (d, 3H, 3JHH ) 6.7 Hz, dCHCH3),
3
1
5.21 (q, 1H, JHH ) 6.7 Hz, dCHCH3), 7.05 (m, 1H, CarH), 7.10
H, 7.17. Found: C, 48.18; H, 7.14. H NMR (C6D6, 20 °C, 300
3
(m, 2H, CarH), 7.58 (d, 1H, JHH ) 7.3 Hz, CarH). 13C{1H} NMR
MHz): δ 0.78 (t, 18H, *JHP ) 3.8 Hz, PMe3), 1.24 (t, 3H, 3JHH
)
7.3 Hz, CH2CH3), 2.76 (q, 2H, 3JHH ) 7.3 Hz, CH2CH3), 6.73 (m,
1H, CarH), 6.89 (dt, 1H, 3JHH ) 7.3 Hz, 4JHH ) 1.5 Hz, CarH), 7.44
(C6D6, 20 °C, 100 MHz): δ 11.8 (s, CHCH3), 16.3 (d, JCP ) 22
Hz, PMe3), 86.5 (s, CHCH3), 121.6 (s, CarH), 123.9 (s, CarH), 124.2
(s, CarH), 136.7 (s, CarH), 155.8 (bs, Car-Ni), 157.4 (s, Car-CO),
169.0 (s, CO). 31P{1H} NMR (C6D6, 20 °C, 162 MHz): δ -13.7
(bs, PMe3).
4
(dd, 1H, 3JHH ) 7.8 Hz, JHH ) 1.3 Hz, CarH), 7.80 (dd, 1H, 3JHH
4
)7.5 Hz, JHH ) 1.0 Hz, CarH). 13C{1H} NMR (C6D6, 20 °C, 75
1
MHz): δ 8.9 (s, CH2CH3), 12.7 (t, JCP ) 13 Hz, PMe3), 31.5 (s,
Synthesis of 2d. A solution of 0.27 g (2.3 mmol) of KtBuO in
5 mL of THF was added to a cooled solution (-78 °C) of 1.05 g
of 1d (2.1 mmol) dissolved in 10 mL of THF. After reaching room
temperature, solvent was removed in vacuo, and 20 mL of toluene
was added. After centrifugation, the solution was taken to dryness
and the residue extracted with 10 mL of THF. Concentration of
this solution and cooling at -20 °C afforded the product as red
crystals. Yield: 42%. Anal. Calcd for C25H30NiOP2: C, 64.28; H,
6.47. Found: C, 63.90; H, 6.44. IR (Nujol mull): ν(CdC), 1573
cm-1. 1H NMR (CD2Cl2, 20 °C, 300 MHz): δ 1.49 (d, 12 H, 2JHP
) 8.0 Hz, PMe2Ph), 1.81 (d, 3H, 3JHH ) 6.8 Hz, CHCH3), 4.72 (q,
CH2CH3), 120.7 (s, CarH), 128.7 (s, CarH), 129.5 (s, CarH), 137.0
2
(t, JCP ) 4 Hz, CarH), 142.4 (s, Car-CO), 171.4 (t, JCP ) 35 Hz,
Car-Ni), 201.9 (s, CO). 31P{1H} NMR (C6D6, 20 °C, 121 MHz): δ
-16.2 (PMe3).
Synthesis of Ni(C6H4-o-C(O)CH3)(Cl)(PMe2Ph)2 (1c). Di-
methylphenylphosphine (1.42 mL, 10 mmol) was added to a cooled
solution (-78 °C) of 1.37 g (5 mmol) of Ni(cod)2 in 50 mL of
toluene. The mixture was allowed to reach room temperature, and
0.65 mL (5 mmol) of 2-chloroacetophenone was added. The reaction
mixture was heated at 45 °C for 4 h. The solvent was removed
under vacuum and the residue extracted with 10 mL of THF. Dark
red crystals of the pure product were obtained after adding some
diethyl ether and cooling at -20 °C. Yield: 50%. Anal. Calcd for
C24H29ClNiOP2: C, 58.88; H, 5.97. Found: C, 58.40; H, 6.07. IR
(Nujol mull): ν(CdO) 1642 cm-1. 1H NMR (CD2Cl2, 20 °C, 300
MHz): δ 0.87 (bs, 6H, PMe2Ph), 1.40 (bs, 6H, PMe2Ph), 2.43 (s,
3H, CH3), 6.75 (td, 1H, 3JHH ) 7.4 Hz, 4JHH ) 1.1 Hz, CarH), 6.82
3
1H, JHH ) 6.8 Hz, CHCH3), 6.55-6.62 (m, 2H, CarH), 6.79 (m,
2H, CarH), 7.10 (m, 1H, CarH), 7.34-7.43 (m, 5H, CarH), 7.76 (t,
3
4H, JHP ) 6.8 Hz, CarH). 13C{1H} NMR (CD2Cl2, 20 °C, 75
1
MHz): δ 10.9 (s, CHCH3), 15.3 (d, JCP ) 24 Hz, PMe2Ph), 87.0
(s, CHCH3), 120.6 (s, CarH), 123.4 (s, CarH), 124.2 (s, CarH), 128.9
2
2
(d, JCP ) 9 Hz, CarH), 130.2 (s, CarH), 131.6 (d, JCP ) 11 Hz,
CarH), 137.7 (s, CarH), 154.4 (s, Car), 155.9 (s, Car), 167.9 (s,OC).
31P{1H} NMR (CD2Cl2, 20 °C, 121 MHz): δ 0.4 (bs).
3
4
3
(td, 1H, JHH ) 7.3 Hz, JHH ) 1.7 Hz, CarH), 7.18 (dd, 1H, JHH
4
) 7.4 Hz, JHH )1.4 Hz, CarH), 7.27-7.34 (m, 5H, CarH), 7.37-
7.46 (m, 5H, CarH). 13C{1H} NMR (CD2Cl2, 20 °C, 75 MHz): δ
11.4 (bs, PMeMePh), 13.0 (bs, PMeMePh), 26.3 (s, CH3), 121.6
(s, CarH), 128.2 (s, CarH), 129.2 (s, CarH), 129.5 (s, CarH), 131.0
Synthesis of the Dinuclear Complex 3b. Potassium tert-
butoxide (115 mg, 1 mmol) was dissolved in 5 mL of THF and
added to a cooled solution (-78 °C) of 370 mg of complex 1b (1
mmol) in 20 mL of THF. After reaching room temperature, the
solvent was removed under vacuum, 10 mL of THF was added,
(16) Spartan 04; Wavefunction, Inc.: Irvine, CA, 2004.