Aminoiminophosphoranate Complexes of Pd and Pt
Organometallics, Vol. 28, No. 10, 2009 3027
and 4′ (75%) according to 1H NMR data. 1H NMR (C6D6) δ: 1.07
(d, J ) 6.9 Hz, 6H, CHMe2), 1.10 (d, J ) 6.8 Hz, 6H, CHMe2),
2.60 (sept, J ) 6.9 Hz, 1H, CHMe2); 2.66 (sept, J ) 6.8 Hz, 1H,
CHMe2), 4.06 (br s, 4H, C2H4), 6.70 (d, J ) 7.0 Hz, 2H, C6H4i-
Pr); 6.81 (d, J ) 8.0 Hz, 2H, C6H4i-Pr); 7.01 (m, 6H, m-H and
p-H, Ph); 7.09 (d, J ) 6.7 Hz, 2H, C6H4i-Pr); 7.54 (d, J ) 7.8 Hz,
2H, i-C6H4Pr); 7.83 (dd, J ) 7.3 Hz, J ) 4.4 Hz, 4H, o-H, Ph). 31
P
NMR (C6D6) δ: 72.59 (s, JPt-P) 236.5 Hz); 72.98 (s, JPt-P) 243.4
Hz).
Synthesis of [Pt{Ph2P(NC6H4i-Pr-p)2}(η2-C2H4)Cl] (4). To a
solution of 2 (0.45 g, 1.0 mmol) in benzene (60 mL) was added a
1.40 M solution of n-BuLi in hexane (0.80 mL, 1.12 mmol), and
the reaction mixture was allowed to stir for 2 h at 50 °C. Then
solid [Pt(η2-C2H4)(µ-Cl)Cl]2 (0.30 g, 0.50 mmol) was added to the
solution, and the reaction mixture was stirred at 50 °C for 2 h. The
reaction mixture was cooled to room temperature and filtered.
The filtrate was evaporated to dryness, and the crude product was
purified by recrystallization from hot hexane, affording 0.59 g (83%)
of 4 as a yellow solid. Anal. Calcd for C32H36ClN2PPt: C, 54.12;
H, 5.07; N, 3.94. Found: C, 54.09; H, 5.11; N, 3.75.
Synthesis of [Pd{Ph2P(NC6H4i-Pr-p)2}(PPh3)Cl] (5). To a
solution of 2 (0.45 g, 1.0 mmol) in benzene (50 mL) was added a
1.98 M solution of n-BuLi in hexane (0.60 mL, 1.10 mmol), and
the reaction mixture was then stirred at 50 °C for 2 h. The solution
was cooled to room temperature, and solid [Pd(PPh3)(µ-Cl)(Cl)]2
(0.44 g, 0.50 mmol) was added. The reaction mixture was stirred
overnight at 20 °C and then filtered; the filtrate was concentrated
to 3 mL and precipitated with 30 mL of hexane. The product was
purified by recrystallization from benzene/hexane, affording 0.78 g
(91%) of 5 as red solid. Anal. Calcd for C48H47ClN2P2Pd: C, 67.36;
H, 5.50; N, 3.27. Found: C, 67.02; H, 5.45; N, 3.17.
Synthesis of [Pt{Ph2P(NC6H4i-Pr-p)2}(PPh3)Cl] (6). To a
solution of 2 (0.27 g, 0.60 mmol) in benzene (30 mL) was added
a 1.98 M solution of n-BuLi in hexane (0.33 mL, 0.65 mmol), and
the reaction mixture was heated at 50 °C for 2 h. The solution was
cooled to room temperature, and solid [Pt(PPh3)(µ-Cl)(Cl)]2 (0.32
g, 0.30 mmol) was added. The reaction mixture was refluxed for
4 h, cooled to room temperature, and filtered. The filtrate was
concentrated to 3 mL and precipitated with 30 mL of hexane. The
product was purified by recrystallization from benzene/hexane,
affording 0.41 g (72%) of 6 as a yellow solid. Anal. Calcd for
C48H47ClN2P2Pt: C, 61.05; H, 4.98; N, 2.97. Found: C, 61.08; H,
5.10; N, 2.86.
Synthesis of [Pd{Ph2P(NC6H4i-Pr-p)2}2] (7). To a suspension
of the phosphonium salt 1 (0.53 g, 1.0 mmol) in Et2O (50 mL)
was added at 20 °C a solution of n-BuLi in hexane (1.45 M, 1.7
mL, 2.5 mmol), and the reaction mixture was stirred for 1.5 h. Then,
a solid of [PdCl2(PhCN)2] (0.19 g, 0.50 mmol) was added, and the
reaction mixture was stirred overnight. The solvent was removed
in Vacuo and the residue was extracted with benzene (3 × 20 mL).
The filtered extract was evaporated to dryness; the product was
purified by recrystallization from hot hexane, affording 0.30 g (60%)
of 7 as red solid. Anal. Calcd for C60H64N4P2Pd: C, 71.39; H, 6.35;
N, 5.55. Found: C, 71.24; H, 6.26; N, 5.61.
Figure 6. 3D distribution of the DED within the C-H · · · PdN4
fragment. Isosurface of the DED equal to 0.40 e A-3 is shown in
red.
properties of aminoiminophosphoranate ligands on the structure
of NPN complexes and their relationship to the catalytic
behavior of the NPN complexes are now in progress.
Experimental Details
All manipulations were carried out using standard Schlenk
techniques under an atmosphere of dry argon. Solvents were purified
1
by standard methods and distilled prior to use. H, 31P, and 13C
NMR spectra were obtained on a Bruker AMX-400 spectrometer
and referenced to the residual signals of the deuterated solvent (1H
and 13C) and to 85% H3PO4 (31P, external standard). Elemental
analyses were performed on a Carlo Erba 1106 CHN analyzer. The
following compounds were prepared according to described meth-
ods: [(η2-C2H4)PtCl(µ-Cl)]2,26 [(Ph3P)PdCl(µ-Cl)]2,27 [(Ph3P)PtCl(µ-
Cl)]2,28 [(PhCN)2PdCl2],29 Ph2P(NHC6H4i-Pr-p)2Br (1).15
Synthesis of Ph2P(NHC6H4i-Pr-p)(NC6H4i-Pr-p) (2). (a) To a
suspension of the diaminophosphonium salt 1 (6.3 g, 11.8 mmol)
in Et2O (200 mL) was added at 20 °C a 1.45 M solution of n-BuLi
in hexane (9.8 mL, 14.2 mmol), and the reaction mixture was stirred
for 2 h. The solvent was removed in Vacuo, and the residue was
extracted with C6H6 (60 mL). The extract was filtered and
concentrated to 20 mL, and the product was precipitated with 50
mL of hexane and dried, affording 5.0 g (94%) of 2 as a white
solid. Anal. Calcd for C30H33N2P: C, 79.62; H, 7.35; N, 6.19. Found:
1
C, 79.39; H, 7.38; N, 6.17. H NMR (CDCl3) δ: 1.17 (d, 12H,
CHMe2, J ) 6.9 Hz); 2.77 (sept, 2H, CHMe2, J ) 6.9 Hz); 6.96 (s,
8H, C6H4Pri); 7.45 (m, 6H, m-H + p-H, Ph); 7.94 (dd, 4H, o-H,
Ph, J ) 12.4 Hz, J ) 6.9 Hz). 31P NMR δ: -4.75 (CDCl3), -9.0
(C6D6).
(b) Analogously, reaction of 1 (0.53 g, 1.0 mmol) with NEt3
(0.11 g, 1.1 mmol) in benzene afforded 0.38 g (84%) of 2.
Synthesis of [Pt{Ph2P(NC6H4i-Pr-p)2}(η2-C2H4)X] (4, X )
Cl; 4′, X ) Br). To a suspension of 1 (1.07 g, 2.0 mmol) in Et2O
(80 mL) was added a 1.40 M solution of n-BuLi in hexane (3.3
mL, 4.6 mmol), and the reaction mixture was stirred at 20 °C for
1.5 h. Then solid [Pt(η2-C2H4)(µ-Cl)Cl]2 (0.59 g, 1.0 mmol) was
added and the reaction mixture was stirred overnight. The solvent
was removed in Vacuo and the residue was extracted with C6H6 (3
× 20 mL). The filtered benzene extract was concentrated until the
product started to crystallize and was precipitated with 50 mL of
hexane to give 0.70 g of a yellow solid, which consisted of 4 (25%)
Synthesis of [Pd{Ph2P(NHC6H4i-Pr-p)(NC6H4i-Pr-p)}2Cl2] (8).
A solution of [PdCl2(PhCN)2] (0.19 g, 0.50 mmol) in benzene (30
mL) was added dropwise to a solution of Ph2P(NHC6H4Pri-
p)(NC6H4i-Pr-p) (0.45 g, 1.0 mmol) in benzene (50 mL) and stirred
at 20 °C overnight. The solvent was removed in Vacuo, and the
residue was washed with methanol (3 × 5 mL) and dried to give
0.44 g (82%) of 8 as red solid. Anal. Calcd for C60H66Cl2N4P2Pd:
C, 66.57; H, 6.10; N, 5.18. Found: C, 66.64; H, 6.28; N, 5.11.
X-ray Crystal Structure Determination. Single crystals of 5,
7, and 8 were obtained by slow diffusion of hexane to a solution
of the complex in dichloromethane (5, 8) or in benzene (7).
Diffraction data for 5 and 8 were taken using a Bruker SMART
1000 CCD diffractometer [λ(Mo KR) ) 0.71072 Å, ω-scans] and
(26) Chatt, J.; Searle, M. L.; Liu, C. F.; Wymore, C. E. Inorg. Synth.
1957, 5, 210.
(27) Chatt, J.; Venanzi, L. M. J. Chem. Soc. 1957, 2351.
(28) Goodfellow, R. J.; Venanzi, L. M. J. Chem. Soc. 1965, 7533.
(29) Doyle, J. R.; Slade, P. E.; Jonassen, H. B. Inorg. Synth. 1960, 6,
218.