Metal complexes of biologically important ligands, CLXXIV [1]. Palladium(II) and platinum(II) complexes with schiff bases from 2-(Diphenylphosphino)benzaldehyde and a-amino acid esters

Article abstract of DOI:10.1515/znb-2010-0411

A series of palladium(II) and platinum(II) complexes Cl₂M(P-N-O) (M = Pd, Pt) with bidentate Schiff bases (P-N-O) from 2-(diphenylphosphino) benzaldehyde and a-amino acid esters has been synthesized, using PdCl ₂ or K[PtCl₃(C₂H₄)], respectively. Abstraction of chloride from Cl₂M(P-N-O) (using AgBF₄) has afforded the cationic complexes [(P-N-O)M(Cl)]⁺BF₄- in which the Schiff bases function as tridentate ligands with coordination of the ester group. The structures of Cl₂Pd(Ph₂PC ₆H₄C(H)=N-CH₂CO₂Et) and of [(Cl)Pd(Ph₂PC₆H₄C(H)=NC( H)(CH ₂CH=CH₂)CO₂Me)]⁺BF₄ ^- have been determined by X-ray diffraction. Complexes (L)MCl ₂ and [(L)MCl]⁺BF₄ (M = Pd, Pt) have also been prepared with the reduced Schiff base Ph₂PC₆H ₄CH₂NHC(H)(CH₂Ph)CO₂Me.

Full text of DOI:10.1515/znb-2010-0411

Metal Complexes of Biologically Important Ligands, CLXXIV [1].
Palladium(II) and Platinum(II) Complexes with Schiff Bases from
2-(Diphenylphosphino)benzaldehyde and α-Amino Acid Esters
Bernhard Schreiner, Christian Robl, Barbara Wagner-Schuh, and Wolfgang Beck
Department Chemie und Biochemie, Ludwig-Maximilians-Universita¨t Mu¨nchen,
Butenandtstraße 9 – 13, 81377 Mu¨nchen, Germany
Reprint requests to Prof. W. Beck. E-mail: wbe@cup.uni-muenchen.de
Z. Naturforsch. 2010, 65b, 503 – 510; received December 7, 2009
Dedicated to Professor Reinhard Schmutzler on the occasion of his 75th birthday
A series of palladium(II) and platinum(II) complexes Cl2M(P-N-O) (M = Pd, Pt) with biden-
tate Schiff bases (P-N-O) from 2-(diphenylphosphino)benzaldehyde and α-amino acid esters
has been synthesized, using PdCl2 or K[PtCl3(C2H4)], respectively. Abstraction of chloride
−
from Cl2M(P-N-O) (using AgBF4) has afforded the cationic complexes [(P-N-O)M(Cl)]+BF4
in which the Schiff bases function as tridentate ligands with coordination of the ester
group. The structures of Cl2Pd(Ph2PC6H4C(H)=N-CH2CO2Et) and of [(Cl)Pd(Ph2PC6H4C(H)=N-
−
C(H)(CH2CH=CH2)CO2Me)]+BF4 have been determined by X-ray diffraction. Complexes
(L)MCl2 and [(L)MCl]+BF4 (M = Pd, Pt) have also been prepared with the reduced Schiff base
Ph2PC6H4CH2NHC(H)(CH2Ph)CO2Me.
Key words: 2-(Diphenylphosphino)benzaldehyde, 2-Formylphenyldiphenylphosphine, Palladium,
Platinum, α-Amino Acid Esters, Schiff Bases
Introduction
the following on palladium(II) and platinum(II) com-
plexes of imines from 2-(diphenylphosphino)benz-
aldehyde and α-amino acid esters. During optimiza-
tion reactions for optically active P,N-ligands, Brunner
et al. [12] have synthesized a P,N Schiff base from 2-
(diphenylphosphino)benzaldehyde and tert-butyl-tert-
leucinate, and several Schiff bases from 2-(diphenyl-
phosphino)benzaldehyde and dipeptides have been de-
veloped as ligands for asymmetric conjugate additions
of allylzinc reagents [15].
2-(Diphenylphosphino)benzaldehyde [2 – 4] (2-
formylphenyldiphenylphosphine) is a very versatile
and frequently employed reagent in coordination
chemistry and in metal-catalyzed synthesis [5]. It has
been introduced as P-donor in metal complexes [6],
for the formation of acyl complexes [7a] or for the
formation of dendrons [7b] or Salpen-like ligands [7c].
Mostly it has been used for reactions with amines
or functionalized amines to synthesize iminophos-
phine ligands (Schiff bases) [8] and optically active
iminophosphines from optically active amines for
asymmetric reactions [9]. Reactions of 2-(diphenyl-
Results and Discussion
The Schiff bases 1 – 5 (Scheme 1) have been ob-
phosphino)benzaldehyde with polyamines afford tained by condensation of 2-(diphenylphosphino)benz-
multidentate iminophosphines [10]. Brunner and aldehyde with α-amino acid esters. Polarometric mea-
coworkers reported optically active P,N-ligands from
surements showed that racemization took place [16]
2-formylphenyldiphenyl-phosphine and optically when L-amino acids were used. The reactions of 1 – 5
active amines from which chelate complexes were with PdCl2 or K[PtCl3(C2H4)] (Zeise’s salt) afforded
obtained, and these were used for metal-catalyzed
asymmetric hydrogenation and hydrosilylation [4, 11] plexes 6, 9 – 11 and 14 were converted into the cationic
and allylation [12, 13].
the yellow complexes 6 – 15 (Scheme 1). The com-
compounds 16 – 20 by treatment with AgBF4.
In the course of our studies on metal complexes of
The IR spectra of 6 – 15 exhibit two ν(M-Cl) ab-
Schiff bases from α-amino acids [14] we report in sorptions at ∼ 350 cm−1, as expected for the cis-MCl2
c
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B. Schreiner et al. · Metal Complexes of Biologically Important Ligands
CHO
PPh2
Ph
Ph
benzene
P
+
R'O2C
−H2O
H2N−CH−COOR'
N
R
R
1−5
PdCl2 / DMF
or
Zeise's salt / DMF
Verb.
R
R'
M
_________________________
Ph
Ph
1
2
3
4
5
H
i-Pr
Bz
Ph
Allyl
Et
−
−
−
−
−
Cl
Me
Me
Me
Me
P
Cl
R
M
R'O2C
N
6
7
8
9
10
11
12
13
14
15
H
H
Et
Et
Pd
Pt
Pd
Pt
Pd
Pt
Pd
Pt
i-Pr
i-Pr
Bz
Me
Me
Me
Me
Me
Me
Me
Me
H
6−15
Bz
Ph
Ph
Allyl
Allyl
Pd
Pt
AgBF4
CH2Cl2
−AgCl
16
17
18
19
20
H
i-Pr
Bz
Bz
Allyl
Et
Pd
Pt
Pd
Pt
Pd
Me
Me
Me
Me
+
Ph
Cl
Ph
−
O
BF4
P
M
R'O
N
R
H
Scheme 1.
16−20
group. The ν(C=N) band of the complexes 6 – 15 is
shifted by N-M coordination to lower frequencies in
comparison to the free Schiff bases 1 – 5. The large
shift of the ester carbonyl absorption in 16 – 20 to
lower frequencies (compared to that in 1 – 15, ∆ = 60 –
100 cm−1) is clear evidence for coordination of the es-
ter function [1] which causes also a characteristic low-
field shift of the methyl and ethyl ester signals in the
1H NMR spectra and a low-field shift of the carbon sig-
nal of the coordinated carbonyl group in the 13C NMR
spectra. The 31P NMR spectra of 1 – 20 spectra exhibit,
as expected, only one signal. The planar structures of 6
(Fig. 1) and 20 (Fig. 2) could be confirmed by X-ray
structure determination (Table 1). The two Pd–Cl bond
lengths in 6 are distinctly different. The Pd–Cl bond
in trans position to the stronger P-donor is longer than
that of the Pd–Cl bond trans to the weaker N-donor.
The structure of 20 shows the coordination of the es-
ter group [1] (Pd–O2 = 214.3(8) pm) and the nonco-
ordinated allyl group. The P–Pd–N angle in 20 with
a six-membered chelate ring is by 5◦ larger than that
in 6 with a five-membered ring (92.7(2) and 88.1(2)◦,
Fig. 1. Molecular structure of 6 in the crystal. Selcted
bond lengths (pm) and angles (deg): Pd–Cl1 238.9(2),
Pd–Cl2 228.6(2), Pd–N 205.4(5), Pd–P 222.5(2), N–C23
128(1), C5–C23 148(1), C20–O1 120(1); Cl2–Pd–C11
89.2(1), Cl1–Pd–N 92.4(2), P–Pd–N 88.1(2), P–Pd–Cl2
91.0(1), P–Pd–Cl1 172.5(1), Cl2–Pd–N 174.9(2), C6–C5–
C23 124.0(6), C5–C23–N 126.8(6), Pd–N–C23 129.1(5),
Pd–N–C19 116.0(4).
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B. Schreiner et al. · Metal Complexes of Biologically Important Ligands
505
Ph
Ph
P
CH3O2C
N
Ph
NaBH4
MeOH
Ph
Ph
P
CH3O2C
N
H
Ph
21
PdCl2/DMF
or
Ph
Zeise's salt
DMF
Ph
Cl
M
P
Cl
H3CO2C
N
H
Ph
AgBF4 / CH2Cl2
−AgCl
22: M = Pd
23: M = Pt
+
Ph
Ph
Cl
−
P
O
M
BF4
H3CO
N
H
Ph
24: M = Pd
25: M = Pt
Scheme 2.
resp.). The racemization of the Schiff base made it pos-
sible that complex 6 subsequently crystallized in the
centrosymmetric space group P21/n.
The Schiff base 3 was converted into the amine 21
by treatment with tetrahydridoborate,and 21 was again
used as a ligand to give the neutral (22, 23) and
cationic (24, 25) palladium(II) and platinum(II) com-
plexes (Scheme 2). The nitrogen atom in 22 – 25 is
a second chiral center; therefore two diastereomers
(SNSC/RNRC and SNRC/RNSC) are formed which can
be detected by their NMR signals.
The IR spectra of 24 and 25 exhibit the charac-
teristic CO absorption of the coordinated ester group
which is typically [1] shifted by ∼ 100 cm−1 to lower
wavenumbers from that of 22 and 23 with a free es-
ter group. The ν(M-Cl) bands of 24 and 25 are found
at 350 cm−1. In the 13C NMR spectra of 22 and 23
two sets of signals for the two diastereoisomers are
observed. The coordination of the ester group in 24
and 25 causes again a large low field shift of the car-
bonyl signal. Two diastereoisomers can be observed
also in the 31P NMR spectra of 22, 23 and 25 which
show two 31P signals, whereas 24 offers four signals
Fig. 2. Molecular structure of 20 in the crystal. Selcted
bond lengths (pm) and angles (deg): Pd–Cl 226.5(2),
Pd–P 217.5(3), Pd–O2 214.3(8), Pd–N 200.0(7), O2–
C21 122.7(12), N–C19 129.4(14), N–C20 147.3(15), P–C7
182.0(10), C18–C19 148.8(17); P–Pd–Cl 91.9(1), P–Pd–N
92.7(2), Cl–Pd–N 178.1(3), P–Pd–O2 173.5(2), Cl–Pd–O2
94.2(2), N–Pd–O2 81.1(3), Pd–P–C1 116.2(2), Pd–N–C20
110.6(6), Pd–O2–C21 110.0(7).
which, presumably, can be attributed to conformational
isomers of the two diastereoisomers [17].
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B. Schreiner et al. · Metal Complexes of Biologically Important Ligands
Table 1. Crystallographic data of 6 and 20.
J(H-P) = 5.3 Hz, N=CH), 6.92 – 7.47 (14H, arom.), 3.59 (d,
1H, J = 7.6 Hz, α-CH), 2.11m (1H, β-CH), 0.71 (d, 3H,
J = 6.7 Hz, γ-CH), 0.79 (d, 3H, J = 6.2 Hz, γ-CH), 3.57
6
20
Formula
C23H22Cl2NO2PPd C25H24BClF4NO2PPd
(s, 3H, OMe). – 13C NMR ([D6]acetone): δ = 161.5 (d, J =
22 Hz, C=N), 171.4 (CO), 128.0 – 139.6 (arom.), 79.7 (α-
C), 31.4 (β-C), 18.0, 19.0 (γ-C), 51.2 (OMe). – 31P NMR
([D6]acetone): δ = −12.8 (s). – C25H26NO2P (403.4): calcd.
C 74.42, H 6.50, N 3.47; found C 73.55, H 6.88, N 3.92.
Formula weight
Crystal system
Space group
a, pm
b, pm
c , pm
552.8
monoclinic
P21/n
630.1
monoclinic
P21/n
1017.6(5)
2081.3(9)
1220.5(7)
102.76(4)
2.520(5)
4
1047.7(2)
2246.4(4)
1221.9(2)
110.93(1)
2.6860(8)
4
3: Yield 83 %. M. p. 91 – 93 ◦C. – IR (Nujol, cm−1): ν =
β, deg
1
Volume, nm3
Z
1737s (CO), 1632m (C=N). – H NMR (CDCl3): δ = 8.69
(d, 1H, J(H-P) = 5.4 Hz, N=CH), 6.84 – 8.70 (19H, arom.),
4.10 (dd, α-CH), 3.23 (dd, 1H, J = 5.9, 13.7 Hz, β-CH),
2.89 (dd, 1H, J = 8.3, 13.6 Hz, β-CH), 3.57 (s, 3H, OMe). –
13C NMR (CDCl3): δ = 162.4 (d, J = 22.0 Hz, C=N), 171.8
(CO), 126.5 – 139.1 (arom.), 74.6 (α-CH), 39.7 (β-CH), 52.0
(OMe). – 31P NMR (CDCl3): δ = −14.2 (s). – C29H26NO2P
(451.5): calcd. C 77.12, H 5.81, N 3.10; found C 76.86,
H 5.83, N 3.36.
ρcalcd., g cm−3
1.46
1.56
µ, mm−1
1.0
0.9
Diffractometer
Temperature, K
Index ranges
Range 2θ, deg
Syntex R3
303
h, +k,
4 – 50
Siemens R3 m/V
295
l
+h, +k,
5 – 50
5261
4739
3286
331
0.081 / 0.046
1.01 / −0.91
l
Reflections collected 9426
Unique reflections
Refls [I ≥ 2σ(I)]
Refined parameters
R/Rw
4335
3996
150
0.077 / 0.091
1.71 / −0.81
4: Yield 65 %. M. p. 55 – 58 ◦C. – IR (Nujol, cm−1): ν =
1740s (CO), 1630s (C=N). – 1H NMR (CDCl3): δ = 9.05 (d,
1H, J(H-P) = 5.3 Hz, N=CH), 6.88 – 8.20 (19H, arom.), 5.09
(s, 1H, α-CH), 3.61 (s, 3H, OMe). – 13C NMR (CDCl3): δ =
163.0 (d, J = 22.7, C=N), 171.9 (CO), 128.4 – 140.0 (arom.),
77.0 (α-C), 52.9 (OMe). – 31P NMR (CDCl2): δ = −13.7
(s). – C28H24NO2P · MeOH (469.5): calcd. C 74.19, H 6.01,
N 2.98; found C 73.72, H 5.97, N 3.03.
∆ρfin (max / min),
e ×10−6 pm−3
Experimental Section
2-(Diphenylphosphino)benzaldehyde [3] and K[PtCl3-
(C2H4)] (Zeise’s salt) [18] were obtained as described. Un-
less otherwise noted, the NMR spectra were recorded on a
Jeol GSX-270 spectrometer.
5: Yield 71 %. M. p. 48 – 50 ◦C. – IR (Nujol, cm−1): ν =
1728s (CO), 1631m (C=N), 1638 sh (C=C). – 1H NMR
(CD2Cl2): δ = 8.88 (s, 1H, J(H-P) = 5.4 Hz, N=CH), 6.88 –
8.02 (14H, arom.), 5.48 (m, 1H, HC=CH2), 4.88 (d, 1H, J =
2
Schiff base 3
10.3 Hz, HC=CHH trans), 4.95 (dd, 1H, J = 17.1 Hz, J =
2.0 Hz, HC=CHH cis), 3.90 (ψt, 1H, α-CH), 2.38 (m, 1H,
β-CH), 2.54 (m, 1H, β-CH), 3.60 (s, 3H, OMe). – 13C NMR
(CD2Cl2): δ = 162.4 (d, J = 23.1 Hz, C=N), 172.1 (CO),
128.2 – 139.7 (arom.), 73.1 (α-C), 38.0 (β-C), 118.0 (δ-
CH2), 52.3 (OMe). – 31P NMR (CD2Cl2): δ = −14.1(s). –
C25H24NO2P (401.4): calcd. C 74.80, H 6.03, N 3.49; found
C 74.20, H 6.06, N 3.40.
2-(Diphenylphosphino)benzaldehyde (4.0 g, 13.8 mmol)
and freshly destilled L-phenylalanine methyl ester (2.33 g,
13.8 mmol) were heated in benzene (120 mL) under reflux
by use of a water separator for 15 h. The solvent was re-
moved in vacuo, the oily residue was dissolved in diethyl
ether (20 mL), and the product was precipitated with n-
pentane. The colorless Schiff ba◦se was recrystallized from
diethyl ether/n-pentane at −35 C and dried over P4O10 at
r. t. The Schiff bases 1, 2, 4 and 5 were prepared by analo-
gous procedures.
N-(2-Diphenylphosphino)benzyl-phenylalaninmethyl-
ester (21)
◦
1: Yield 71 %. M. p. 85 – 87 C. – IR (KBr, cm−1): ν =
To a solution of Schiff base 3 (2.11 g, 4.67 mmol)
in methanol (25 mL) sodium tetrahydroborate (276 mg,
7.30 mmol) was added slowly at 0 ◦C. The mixture was
heated under reflux for 1 h and methanol was removed in
vacuo. The yellow-brown oily residue was dissolved in di-
ethyl ether, and the solution was filtered. After addition of
water (10 mL) the organic phase was separated. The aque-
ous phase was extracted with diethyl ether. The united ether
phases were dried over Na2SO4 and filtered over silica gel
1
1745s (CO), 1636m (C=N). – H NMR ([D6]acetone): δ =
9.01 (d, 1H, J(H-P) = 5.3 Hz, N=CH), 6.86 – 8.18 (14H,
arom.), 4.26 (d, 2H, J(H-P) = 1.2 Hz, α-CH), 4.10 (q, 2H,
Et), 1.19 (t, 3H, Et). – 13C NMR ([D6]acetone): δ = 163.0
(d, J = 22 Hz, C=N), 127.6 – 139.1 (arom.), 61.6 (α-C),
60.4, 13.8 (OEt). – 31P NMR ([D6]acetone): δ = −14.2(s). –
C23H22NO2P (375.4): calcd. C 73.58, H 5.91, N 3.73; found
C 73.43, H 6.06, N 3.61.
2: Oil. Yield 76 %. – IR (Nujol, cm−1): ν = 1740s (CO), [10 cm, Merck Kieselgel 60 (70 – 210 mesh)]. The ether was
1631m (C=N). – H NMR ([D6]acetone): δ = 8.93 (d, 1H, removed in vacuo, and the oily residue was treated with n-
1
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B. Schreiner et al. · Metal Complexes of Biologically Important Ligands
507
1
pentane. At −30 ◦C a colorless powder was obtained, which Cl). – H NMR (CD2Cl2): δ = 8.44 (s, 1H, N=CH), 7.03 –
was dried at r. t. in vacuo.
7.87 (14H, arom.), 5.94 (d, 1H, J = 9.1 Hz, α-CH), 2.17 (m,
1H, β-CH), 0.82 (d, 6H, J = 6.5 Hz, γ-CH), 3.57 (s, 3H,
OMe). – 13C NMR (CD2Cl2): δ = 167.9 (d, J = 8.1 Hz,
C=N), 171.6 (CO), 120.1 – 138.1 (arom.), 78.2 (α-C), 33.7
(β-C), 18.9, 19.3 (γ-C), 53.1 (OMe). – 31P NMR (CD2Cl2):
δ = 32.0 (s). – C25H26Cl2NO2PPd (580.8): calcd. C 51.7,
H 4.51, N 2.41; found C 51.72, H 4.56, N 2.70.
21: Colorless. Yield 63 %. M. p. 105 – 108 ◦C. – IR (KBr,
cm−1): ν = 3345m (NH), 1737 (CO), 1582m, 1495m (C=C,
δNH). – 13C NMR (CDCl3): δ = 174.7 (CO), 126.6. – 144.1
(arom.), 62.0 (α-C), 51.5 (OMe), 50.3 (d, J = 21, NCH2),
39.4 (β-C). – 31P NMR (CDCl3): δ = −15.5. – C29H28NO2P
(453.5): calcd. C 76.80, H 6.22, N 3.09; found C 75.89,
H 6.38, N 3.02.
◦
9: Light yellow. Yield 67 %. M. p. ¿ 270 C. – IR (Nu-
jol, cm−1): ν = 1745s (CO), 1615m (C=N), 280m, 348m
(Pt-Cl). – 1H NMR (CD2Cl2): δ = 8.56 (s, 1H, J(Pt-H) =
107 Hz, N=CH), 6.96 – 7.91 (14H, arom.), 6.01 (d, 1H, J =
9.7 Hz, α-CH), 2.12 (m, 1H, β-CH), 0.81 (d, 3H, J = 6.4 Hz,
γ-CH), 0.88 (d, 3H, J = 5.9 Hz, γ-CH), 3.58 (s, 3H, OMe). –
31P NMR (CD2Cl2): δ = 6.0 (s, J(Pt-P) = 3728.0 Hz). –
C25H26Cl2NO2PPt (669.5): calcd. C 44.85, H 3.91, N 2.09;
found C 44.47, H 3.95, N 2.39.
Palladium complex 6
A suspension of PdCl2 (177 mg, 1 mmol) in DMF
(10 mL) was heated under reflux for 3 h. The deep-red so-
lution was cooled to r. t., and the Schiff base 1 (376 mg,
1 mmol) was added. After stirring for 1 h the orange-yellow
solution was separated with a pipette and its volume reduced
to 4 mL. ◦The solution was layered with diethyl ether (15 mL).
At −30 C yellow, DMF-containing needles were obtained
which were washed three times with diethyl ether (10 mL
each). The other palladium complexes 8, 10, 12, 14 and 22
were prepared by analogous procedures.
◦
10: Yellow. Yield 71 %. M. p. 198 – 202 C. – IR (Nujol,
cm−1): ν = 1741s (CO), 1631m (C=N), 280m, 348m (Pd-
Cl). – 1H NMR (CDCl3): δ = 7.89 (s, 1H, N=CH), 6.98 –
7.73 (19H, arom.), 6.33 (dd, 1H, J = 4.2 Hz, J = 8.8 Hz,
α-CH), 3.70 (dd, 1H, J = 4.4 Hz, 2J = 13.2 Hz, β-CH),
3.22 (dd, 1H, J = 9.0, 2J = 13.2 Hz, β-CH), 3.36 (s, 3H,
OMe). – 13C NMR (CDCl3): δ = 167.8 (d, J = 8.4 Hz,
C=N), 170.6 (CO), 121.4 – 137.1 (arom.), 73.0 (α-C), 40.6
(β-C), 52.3 (OMe). – 31P NMR (CDCl3): δ = 32.2 (s). –
C29H26Cl2NO2PPd (628.8): calcd. C 55.39, H 4.17, N 2.23;
found C 54.89, H 4.31, N 2.27.
Platinum complex 23
To Zeise salt (K[PtCl3C2H4], 369 mg, 1 mmol) dissolved
in DMF (12 mL) compound 21 (404 mg, 1 mol) was added.
After stirring for 12 h the light-yellow solution was separated
with a pipette and its volume reduced to 4 mL while warm-
◦
◦
11: Yellow. Yield 69 %. M. p. 185 – 188 C. – IR (Nujol,
ing to r. t. and layered with n-pentane (15 mL). At −30 C
cm−1): ν = 1741s (CO), 1616m (C=N), 290m, 346m (Pt-
Cl). – 1H NMR (CDCl3): δ = 8.05 (s, 1H, J(Pt-H) = 102 Hz,
N=CH), 7.02 – 7.68 (19H, arom.), 6.55 (dd, 1H, J = 4.2 Hz,
J = 8.6 Hz, α-CH), 3.67 (dd, 1H, J = 4.2 Hz, 2J = 13.2 Hz,
β-CH), 3.22 (dd, 1H, J = 8.6 Hz, 2J = 13.2 Hz, β-CH),
3.41 (s, 3H, OMe). – 13C NMR (CDCl3): δ = 166.2 (d, J =
7.3 Hz, C=N), 170.8 (CO), 122.1 – 137.1 (arom.), 74.2 (d,
5J = 4.2 Hz, α-C), 53.2 (OMe). – 31P NMR (CDCl3): δ =
6.4 (s, J(Pt-P) = 3752.2. – C29H26Cl2NO2PPt (717.5): calcd.
C 48.54, H 3.65, N 1.95; found C 48.23, H 3.74, N 2.00.
12: Yellow. Yield 65 %. M. p. 201 ◦C. – IR (Nujol, cm−1):
colorless crystals were obtained which were washed three
times with diethyl ether (10 mL each). The other platinum
complexes 7, 9, 11, 13 and 15 were prepared by analogous
procedures.
◦
6: Yellow. Yield 86 %. M. p. 224 – 228 C. – IR (Nujol,
cm−1): ν = 1736 (CO), 1626m (C=N), 252m, 340m (Pd-
Cl). – 1H NMR ([D7]DMF): δ = 8.77 (s, 1H, N=CH), 7.25 –
8.11 (14 H, arom.), 5.39 (s, 2H, α-CH), 4.08 (q, 2H, Et), 1.16
(t, 3H, J = 7.0 Hz, Et). – 13C NMR ([D7]DMF): δ = 171.1
(d, J = 8.4 Hz, C=N), 168.8 (s, CO), 122.1 – 138.3 (arom.),
66.1 (α-C), 61.8, 14.3 (Et). – 31P NMR ([D7]DMF): δ = 29.5
(s). – C23H22Cl2NO2PPd · 1/2 DMF (589.3): calcd. C 49.94, ν = 1740s (CO), 1620m (C=N), 278m, 342m (Pd-Cl). – 13
C
H 4.36, N 3.57; found C 49.40, H 4.24, N 3.◦63.
NMR (CDCl3): δ = 168.7 (d, J = 7.9 Hz, C=N), 170 (CO),
121.4 – 137.1 (arom.), 77.3 (α-C), 53.2 (OMe). – 31P NMR
(CDCl3): δ = 32.4 (s). – C28H24Cl2NO2PPd (614.8): calcd.
C 54.70, H 3.93, N 2.28; found C 54.49, H 3.96, N 2.47.
7: Orange. Yield 80 %. M. p. 206 – 209 C. – IR (Nujol,
cm−1): ν = 1733s (CO), 1626m (C=N), 304m, 350sh (Pt-
N). – 1H NMR ([D7]DMF): δ = 9.06 (s, 1H, N=CH), 7.30 –
8.15 (14H, arom.), 5.58 (s, 2H, α-CH), 4.07 (q, 2H, Et), 1.15
(t, 3H, Et). – 13C NMR ([D7]DMF): δ = 170.0 (d, J = 7.3 Hz,
C=N), 168.8 (CO), 121.2 – 138.0 (arom.), 66.7 (α-C), 61.9,
14.2 (Et). – 31P NMR ([D7]DMF): δ = 3.7 (s, J(Pt-P) =
3738.8 Hz). – C23H22Cl2NO2PPt (641.4): calcd. C 43.07,
◦
13: Light-yellow. Yield 79 %. M. p. 214 C. – IR (Nu-
jol, cm−1): ν = 1742s (CO), 1620m (C=N), 290m, 350m
(Pt-Cl). – 13C NMR (CDCl3): δ = 169.5 (CO), 167.4
(d, J = 7.4 Hz, C=N), 121.9 – 136.0 (arom.), 76.7 (α-
C), 53.2 (OMe). – 31P NMR (CDCl3): δ = 6.0 (s, J(Pt-
P) = 3739.8 Hz). – C28H24Cl2NO2PPt (703.5): calcd.
H 3.46, N 2.18; found C 42.90, H 3.69, N 2.24.
◦
8: Yellow. Yield 57 %. M. p. 231 – 232 C. – IR (Nujol, C 47.81, H 3.44, N 1.99; found C 47.79, H 3.54,
cm−1): ν = 1740s (CO), 1623m (C=N), 282m, 346m (Pd- N 2.22.
Unauthenticated
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508
B. Schreiner et al. · Metal Complexes of Biologically Important Ligands
14: Yellow. Yield 63 %. M. p. 210 ◦C. – IR (Nujol, cm−1): (s, 2H, α-CH), 4.54 (q, 2H, Et), 1.40 (t, 3H, J = 7.2,
ν = 1723s (CO), 1629m (C=N), 1640w (C=C), 286m, 352 Et). – 13C NMR (CD2Cl2): δ = 168.0 (d, J = 5.8 Hz,
m (Pd-Cl). – 1H NMR (CDCl3/[D7]DMF): δ = 8.44 (s, C=N), 181.4 (d, J = 1.5 Hz, CO), 117.3 – 140.4 (arom.),
1H, C=NH), 7.00 – 7.97 (14H, arom.), 6.16 (ψt, 1H, α-CH), 66.4 (α-C), 67.6, 14.0 (Et). – 31P NMR (CD2Cl2): δ = 39.7
2.65 (m, 1H, β-CH), 2.83 (m, 1H, β-CH), 5.55 (m, 1H, (s). – C23H22BClF4NO2PPd (604.1): calcd. C 45.73, H 3.67,
HC=CH2), 4.88 (s, 1H, HC=CHH trans), 4.83 (d, 1H, J = N 2.32; found C 45.12, H 3.93, N 2.55.
5.3 Hz, HC=CHH cis), 3.55 (s, 3H, OMe). – 13C NMR
(CDCl3/[D7]DMF): δ = 170.1 (d, J = 8.7 Hz, C=N), 170.7
(CO), 120.1 – 138.1 (arom.), 72.7 (α-C), 38.4 (β-C), 119.1
(δ-C), 53.0 (OMe). – 31P NMR (CDCl3/[D7]DMF): δ = 32.1
(s). – C25H24Cl2NO2PPd (578.8): calcd. C 51.88, H 4.18,
N 2.42; found C 51.50, H 4.30, N 2.81.
◦
17: Yellow. Yield 90 %. M. p. 175 – 180 C. – IR (Nujol,
cm−1): ν = 1642s (CO), 1618s (C=N), 1058vs (BF4), 354m
(Pt-Cl). – 1H NMR (CD2Cl2): δ = 8.99 (s, 1H, J(H-Pt) =
110 Hz, N=CH), 7.26 – 8.32 (14H, arom.), 5.42 (d, 1H, J =
5.7 Hz, α-CH), 2.38m (m, 1H, β-CH), 1.00 (d, 3H, γ-CH),
0.91 (d, 3H, J = 6.8 Hz, γ-CH), 4.23 (s, 3H, OMe). – 13C
NMR (CD2Cl2): δ = 165.3 (d, J = 4.2 Hz, C=N), 187.1 (CO),
117.1 – 140.4 (arom.), 83.4 (α-C), 36.4 (β-C), 18.3, 18.7 (γ-
C), 53.3 (d, J = 2.1 Hz, OMe). – 31P NMR (CD2Cl2): δ =
2.3 (J(Pt-P) = 4199.8 Hz). – C23H30BClF4NO2PPt · CH2Cl2
(809.7): calcd. C 38.56, H 3.98, N 1.73; found C 50.72,
H 4.15, N 2.08.
15: Yellow. Yield 81 %. M. p. 212 ◦C. – IR (Nujol,
cm−1): ν = 1724s (CO), 1618m (C=N), 1641w (C=C), 286m,
353m (Pt-Cl). – 13C NMR (DMF/[D7]DMF): δ = 168.9
(d, J = 7.3 Hz, C=N), 170.9 (CO), 121.2 – 138.0 (arom.),
73.8 (α-C), 38.5 (β-C), 119.3 (δ-C), 53.1 (OMe). – 31P
NMR (DMF/[D7]DMF): δ = 6.4 (s, J(Pt-P) = 3724.0 Hz). –
C25H24Cl2NO2PPt · 1/4 DMF (685.7): calcd. C 45.10,
H 3.79, N 2.55; found C 44.08, H 3.70, N 2.50.
◦
18: Light-yellow. Yield 96 %. M. p. 218 C. – IR (Nu-
jol, cm−1): ν = 1662s, 1642m (CO), 1617sh (C=N), 1062vs
(BF4), 356m (Pd-Cl). – 1H NMR (CD2Cl2): δ = 8.16 (d,
1H, J(H-P) : 3.0 Hz, N=CH), 6.62 – 8.02 (19H, arom.), 5.67
(dd, 1H, α-CH), 3.53 (dd, 1H, 2J = 14 Hz, J = 5.0 Hz),
3.24 (dd, 1H, 2J = 14.0 Hz, J = 8.8 Hz, β-CH), 4.14
(s, 3H, OMe). – 13C NMR (CD2Cl2): δ = 166.9 (d, J =
6.0 Hz, C=N), 183.9 (CO), 118.0 – 140.7 (arom.), 79.0 (α-
C), 42.0 (β-C), 58.6 (OMe). – 31P NMR (CD2Cl2): δ = 39.5
(s). – C29H26BClF4NO2PPd (680.2): calcd. C 51.21, H 3.85,
N 2.06; found C 50.72, H 4.15, N 2.08.
◦
22: Yellow. Yield 75 %. M. p. 218 – 220 C. – IR (Nu-
jol, cm−1): ν = 3192m (NH), 1733s (CO), 1491m, 1567w,
1581w, 1599 (C=C, NH), 295m, 338m (Pd-Cl). – 13C
NMR (DMF/CD2Cl2): δ = 170.4 [170.6] (CO), 123.3 –
139.3 (arom.), 64.5 [66.4] (α-C), 52.6 [53.7] (OCH3), 52.3
(NCH2), 40.1 [38.6] (β-C). – 31P NMR (DMF/CD2Cl2): δ =
17.7, 18.4. – C29H28Cl2NO2PdPd (630.8): calcd. C 55.22,
H 4.47, N 2.22; found C 54.70, H 4.65, N 2.41.
23: Light-yellow. Yield 66 %. M. p. 191 – 196 ◦C. –
IR (KBr, cm−1): ν = 3180m (NH), 1739s (CO), 1480m,
1567w, 1583w, 1598w (C=C, NH), 300m, 342m (Pt-
Cl). – 13C NMR (DMF/CD2Cl2): δ = 169.0, 169.9 (CO),
122.6 – 139.1 (arom.), 66.5, 67.9 (α-C), 52.9 (OCH3), 52.3
(NCH2), 41.0, 37.7 (β-C). – 31P NMR (DMF/CD2Cl2): δ =
−4.3 (J(Pt-P) = 3927 Hz), −6.5 (J(Pt-P) = 3887 Hz). –
C29H28Cl2NO2PPt · 1/2 DMF (756.1): calcd. C 48.45,
H 4.20, N 2.78; found C 48.56, H 4.16, N 2.88.
◦
19: Light-yellow. Yield 92 %. M. p. 234 – 236 C. – IR
(Nujol, cm−1): ν = 1648s (CO), 1627m (C=N), 1058vs
(BF4), 361m (Pt-Cl). – 1H NMR (CD2Cl2): δ = 8.28 (s,
1H, J(H-Pt) = 111 Hz), 6.62 – 7.93 (19H, arom.), 5.81 (dd,
1H, J = 4.4 Hz, J = 8.8 Hz, J(H-Pt) = 30 Hz, α-CH), 3.53
(dd, 1H, 2J = 14.0 Hz, J = 4.7 Hz, β-CH), 3.27 (dd, 1H,
2J = 14.0 Hz, J = 9.0 Hz, β-CH), 4.25 (s, 3H, OMe). – 13
C
NMR (CD2Cl2): δ = 164.5 (d, J = 4.2 Hz, C=N), 187.2 (d,
J = 1.6 Hz, CO), 116.4 – 140.2 (arom.), 79.4 (α-C), 42.2 (β-
C), 58.5 (Me). – 31P NMR (CD2Cl2): δ = 1.6 (J(Pt-P) =
4218.7 Hz). – C29H26BClF4NO2PPt · 1/2CH2Cl2 (811.4):
calcd. C 43.67, H 3.35, N 1.73; found C 43.05, H 3.64,
N 1.72.
Cationic complexes 16 – 20, 24 and 25
In a dry Schlenk tube to 1 mmol of 6, 9, 10, 11, 14, 15,
22 or 23 and 1.1 mmol of AgBF4 dichloromethane (10 mL)
was added, and the mixture was stirred for 2 h. Then, the
solution was filtered, and the solvent was removed from the
filtrate in vacuo. The residue was dried in vacuo at 60 ◦C and
then stirred with diethyl ether (15 mL) for 14 h. The diethyl
ether was decanted, and the solid product was washed twice
with diethyl ether (10 mL each) and dried in vacuo at 60 ◦C
for 6 h.
◦
20: Yellow. Yield 93 %. M. p. 193 – 196 C. – IR (Nu-
jol, cm−1): ν = 1663s (CO), 1611w (C=N), 1640sh (C=C),
1058vs (BF4), 348w (Pd-Cl). – 1H NMR (CD2Cl2): δ =
8.66 (d, 1H, J(H-P) = 3.4 Hz, N=CH), 7.19 – 8.23 (14H,
arom.), 5.75 (m, 1H, HC=CH2), 5.00 (d, 1H, J = 10.2 Hz,
HC-CHH trans), 4.46 (d, 1H, J = 16.6 Hz, HC=CHH cis),
5.42 (ψt, 1H, α-CH), 2.71 (m, 1H, β-CH), 2.82 (m, 1H, β-
◦
16: Yellow. Yield 91 %. M. p. 180 – 182 C. – IR (Nu- CH), 4.01 (s, 3 H, OMe). – 13C NMR (CD2Cl2): δ = 167.4
jol, cm−1): ν = 1646 (CO), 1613m (C=N), 1062vs (BF4), (d, J = 5.1 Hz, C=N), 181.4 (CO), 117.6 – 140.3 (arom.),
353w (Pd-Cl). – 1H NMR (CD2Cl2): δ = 8.81 (d, 1H, 78.1 (α-C), 39.5 (β-C), 56.6 (Me), 122.2 (δ-C). – 31P NMR
J(H-P) = 2.4 Hz, N=CH), 7.30 – 8.20 (14H, arom.), 5.30 (CD2Cl2): δ = 40.3 (s). – C25H24BClF4NO2PPd (630.1):
Unauthenticated
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B. Schreiner et al. · Metal Complexes of Biologically Important Ligands
509
calcd. C 47.66, H 3.84, N 2.22; found C 47.14, H 3.95, Crystal structure determination of 6 and 20
N 2.32.
X-Ray intensities were collected at r. t. with four-circle
diffractometers using graphite-monochromatized MoKα ra-
diation. The data were corrected for Lorentz and polarization
effects. An empirical absorption correction was applied for 6.
The phase problem was solved by Direct Methods (20) and
Patterson techniques (6). The SHELXTL-PLUS suite of pro-
grams were used for structure solution and refinement [19].
The crystallographic data are compiled in Table 1.
CCDC 766317 (6) and 759892 (20) contain the supple-
mentary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data request/
cif.
24: Yellow. Yield 91 %. M. p. 202 – 208 ◦C. – IR (Nu-
jol, cm−1): ν = 3180 m, br (NH), 1641s, 1737w (CO),
1499w, 1571w, 1589w (C=C, NH), 1060vs (BF4), 345 (Pd-
Cl). – 13C NMR (CD2Cl2): δ = 185.1 (CO), 128.4 – 135.0
(arom.), 70.9 (α-C), 56.7 (OMe), 53.9 (NCH2), 38.0 (β-
C). – 31P NMR (CD2Cl2): δ = 32.2, 28.1, 25.0, 24.8
(1 : 3 : 4 : 1). – C29H28BClF4NO2PPd · 1/2CH2Cl2 (724.7):
calcd. C 48.90, H 4.03, N 1.93; found C 48.49, H 4.25,
N 2.25.
◦
25: Colorless. Yield 85 %. M. p. 210 – 214 C. – IR (Nu-
jol, cm−1): ν = 3175m, br (NH), 1741w, 1630s (CO), 1496w,
1569w, 1576sh, 1580sh (C=C, NH), 1080vs (BF4), 348w (Pt-
Cl). – 13C NMR (CD2Cl2): δ = 187.5 (CO), 121.6 – 137.5
(arom.), 69.6 (α-C), 36.4 (β-C), 53.5 (N-CH2), 36.4 (β-C). –
31P NMR (CD2Cl2): δ = −5.5 (J(Pt-P) = 4287 Hz), −3.2
(J(Pt-P) = 4337 Hz) (3 : 1). – C29H28BClF4NO2PPt · 1/2
CH2Cl2 (813.3): calcd. C 43.56, H 3.59, N 1.72; found
C 42.71, H 3.87, N 2.10.
Acknowledgement
We thank Deutsche Forschungsgemeinschaft, Fonds der
Chemischen Industrie, Wacker-Chemie AG Mu¨nchen, and
Ludwig-Maximilians-Universita¨t Mu¨nchen for support.
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