M. Keleş and M. K. Yılmaz
Preparation of Ligands and Complexes
General Procedure for Suzuki Cross-Coupling
Preparation of ((Ph2PCH2)2NC6H4―2-(CF3)) (1a)
An oven-dried Schlenk flask was charged with base (2 mmol) and
organic solvent–H2O (3/3 mL) under nitrogen atmosphere
followed by aryl halide (1 mmol), aryl boronic acid (1.5 mmol)
and Pd(II) catalyst (1 mol%). The flask was then sealed under N2
atmosphere and placed in an oil bath pre-heated at 80 °C.
The reaction mixture was stirred and then allowed to cool to
room temperature. The reaction mixture was poured into water
(5 mL) and extracted with CHCl3 (3 × 20 mL). The extracts were
washed with brine and dried over MgSO4 and solvent was
evaporated.
A mixture of Ph2PH (1.5 mL, 8.0 mmol), HCHO (0.8 mL, 14 mmol),
and 2-(trifluoromethyl)aniline (0.65 g, 4 mmol) was refluxed for
2 h in toluene (10 mL). The reaction mixture was then allowed
to cool to room temperature. The product was extracted with
CH2Cl2, dried over MgSO4 and filtered off. The filtrate was
evaporated under reduced pressure until dryness to give the title
1
compound 1a, 1.65 g (74%). H NMR (400.1 MHz, CDCl3), δ ppm:
7.82–7.75 (m, 21H, CH, arom.), 7.46–7.41 (m, 1H, CH, arom.),
7.38–7.33(m, 1H, CH, arom.), 7.15–6.92 (m, 1H, CH, arom.), 4.04
(d, J = 4.3 Hz, 4H, CH2). 13C NMR (100.6 MHz, CDCl3), δ ppm:
149.19 (C1, ArC―N), 136.40 (d, JPC = 14.4 Hz), 133.15 (d, JPC = 18.8
Hz), 132.18 (C3), 131.86 (CH), 131.36 (d, JPC = 9.3 Hz), 130.79
(C4,CH), 129.32 (CH), 128.79 (d, JPC = 6.6 Hz), 125.03 (C6, C2),
122.32 (CF3) 55.67 (d, JPC = 13.1 Hz, N―CH2―P). 31P NMR
Results and Discussion
Ligands 1a and 1b were synthesized by treating
diphenylphosphine (HPPh2) with appropriate CF3-substituted
anilines according to the Mannich reaction. The Pd(II) complexes
of the aminomethyldiphosphine ligands (2a, 2b) were prepared
under argon atmosphere using Schlenk techniques as shown
in Scheme 1.
(162 MHz, CDCl3),
C33H28F3NP2: C, 71.09; H, 5.06; N, 2.51 %. Found: C, 70.43; H,
5.62; N, 2.62%.
δ
ppm: À18.84 (PPh2). Anal. calcd for
The ligand 1b was prepared as described in procedure 1a.
Preparation of ((Ph2PCH2)2NC6H4―3-(CF3)) (1b)
Characterization of CF3-Substituted Aminomethyldiphosphine
Ligands and their Pd(II) Complexes
Yield 1.60 g (71%).1H NMR (400.1 MHz, CDCl3), δ ppm: 7.55–7.44
(m, 20H, CH, arom.), 6.85–7.28 (m, 4H, CH, arom.), 3.84 (d,
J = 4.9 Hz., 4H, CH2). 13C NMR (100.6 MHz, CDCl3), δ ppm: 144.20
(C1, ArC―N), 132.63 (d, JPC = 13.8 Hz), 131.56 (d, JPC = 12.1 Hz),
131.35 (C3), 131.12 (CH), 130.71 (d, JPC = 11.4 Hz), 129.00 (C4, CH),
128.87 (CH) 127.92 (d, JPC = 7.1 Hz), 128.46 (C6, C2), 128.28 (CF3),
60.70 (d, JPC = 12.0 Hz, N―CH2―P). 31P NMR (162 MHz, CDCl3), δ
ppm: À19.25 (PPh2). Anal. calcd for C33H28F3NP2: C, 71.09; H,
5.06; N, 2.51%. Found: C, 70.14; H, 4.92; N, 2.84%.
The structures of compounds (1a–2b) were characterized by the
1H NMR, 13C NMR, 31P NMR and elemental analysis.
It was found that although the metal complexes (2a, 2b) are
very soluble in CH2Cl2, CHCl3, CH3CH2OH and acetone, they are
insoluble in diethyl ether and n-hexane. These complexes are sta-
ble both in air and in organic solvent. The 1H NMR spectra of the
ligands (1a, 1b) and their Pd(II) complexes (2a, 2b) showed that
the protons of the phenyl ring were at 6.92–7.95 ppm. The 1H
NMR spectrum of ligands and their Pd(II) complexes 1a–2b ap-
pear at 3.84–4.43 ppm, corresponding to the methylenic (PCH2N)
protons respectively. Additionally, there is no remarkable differ-
ence between the free ligands and their Pd(II) complexes in the
1H NMR spectra. The NCH2P signals of 2a and 2b slightly
shifted downfield when compared to the free ligands 1a
and 1b. As a result of this, the N atom was not coordinated
to Pd(II) as reported in the literature.[23,24] The 31P{1H} NMR
spectra of all compounds (1a–2b) manifested that a singlet
Preparation of [PdCl2 ((Ph2PCH2)2NC6H4―2-(CF3))] (2a)
To a solution of [Pd(cod)Cl2] (0.10 g, 0.35 mmol) in CH2Cl2 (10 mL)
was added 1a (0.20 g, 0.36 mmol). The mixture was stirred for 6 h
at reflux. Then, addition of diethyl ether caused the formation of
a yellow solid, which was filtered off and dried to give the title
compound 2a. Yield 0.17 g (80%), m.p. 158–159 °C. 1H NMR
(400.1 MHz, CDCl3), δ ppm: 7.95–7.71 (m, 20H, CH, arom.),
7.57–7.45 (m, 1H, CH, arom.), 7.40–7.35 (m, 1H, CH, arom.),
7.32–7.26 (m, 1H, CH, arom.), 4.40 (d, J = 1.8 Hz, 4H,
CH2). 13C NMR (100.6 MHz, CDCl3), δ ppm: 146.43 (C1,
ArC―N), 139.36 (C9), 132.23 (C5), 132.09 (C10, C14),
131.84 (C11, C12, C13), 131.77 (C3), 130.98 (C4), 128.56
(C6) 127.90 (CF3), 55.82 (C7, C8, N―CH2―P). 31P NMR
(162 MHz, CDCl3), δ ppm: 8.03 (Pd―PPh2). Anal. calcd
for C33H28Cl2F3NP2Pd: C, 53.94; H, 3.84; N, 1.91%. Found:
C, 55.01; H, 3.92; N, 2.14%.
The complex 2b was prepared as described for proce-
dure 2a.
P
R1
NH2
R1
6
toluene
reflux
7
R2
N
5
8 P
HPPh2
+
CH2O
+
R2
9
1
2
14
13
4
10
11
3
12
R1: CF3, R2: H (1a)
R1: H, R2: CF3 (1b)
Preparation of [PdCl2((Ph2PCH2)2NC6H4―3-(CF3))] (2b)
1
Yield 0.15 g (78%), m.p. 248–250 °C. H NMR (400.1MHz,
Ph2
Cl
P
CDCl3), δ ppm: 7.52–7.09 (m, 20H, CH, arom.), 7.88–7.70
Pd
PPh2
PPh2
R1
CH2Cl2
reflux
R1
Cl
(m, 4H, CH, arom.), 4.43 (d, J = 2.1Hz, 4H, CH2). 13C NMR
PPh2
R2
N
R2
N
[Pd(cod)Cl2]
+
(100.6 MHz, CDCl3), δ ppm: 148.82 (C1, ArC―N), 137.59
(C9), 132.37 (C5), 132.02 (C10, C14), 131.69 (C11, C12,C13),
130.81 (C2), 130.72 (C4), 129.06 (C6) 126.90 (CF3), 59.21
(C7, C8, N―CH2―P). 31P NMR (162 MHz, CDCl3), δ ppm:
9.56 (Pd―PPh2). Anal. calcd for C33H28Cl2F3NP2Pd: C,
R1: CF3, R2: H (2a)
R1: H, R2: CF3 (2b)
Scheme 1. Synthesis of CF3-substituted aminomethyldiphosphine ligands and
53.94; H, 3.84; N, 1.91%. Found: C, 54.74; H, 4.08; N, 2.10%. their Pd(II) complexes.
wileyonlinelibrary.com/journal/aoc
Copyright © 2013 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2014, 28, 91–94