1D and 2D Nuclear magnetic resonance of new silver(I) complexes with achiral and chiral bases as ligands: Crystal structure of [Ag{(S)-(6-CH3)C5H3N-CHN-CH(α-CH 3)C6H5}(PPh3)2](O 3SCF3)

Article abstract of DOI:10.1016/j.ica.2011.09.033

Treatment of equimolar amounts of substituted aniline or amine with substituted benzaldehyde leads to the corresponding achiral or chiral Schiff bases (L). The reaction of the bases with [Ag(O₃SCF ₃)(PPh₃)] leads to the preparation of three or four coordinated cationic complexes, [Ag(k¹-L)(PPh₃) _n]⁺ (n = 1 or 2) which have been characterized by IR, ¹D and ²D NMR spectroscopy. The crystal structure of [Ag{(S)-(6-CH₃)C₅H₃N-CHN-CH(α-CH ₃)C₆H₅}(PPh₃)₂](O ₃SCF₃) is reported.

Full text of DOI:10.1016/j.ica.2011.09.033

Inorganica Chimica Acta 379 (2011) 81–89
Contents lists available at SciVerse ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
2
1D and D Nuclear magnetic resonance of new silver(I) complexes with achiral
and chiral bases as ligands: Crystal structure of
[Ag{(S)-(6-CH3)C5H3N-CHN-CꢀH(
a-CH3)C6H5}(PPh3)2](O3SCF3)
b,
b
Olga Cifuentes a, Raúl Contreras a, , Antonio Laguna , Olga Crespo
⇑
⇑
a Departamento de Química Inorgánica, Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, Santiago-6094411, Chile
b Departamento de Química Inorgánica, Universidad de Zaragoza-CSIC, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Pedro Cerbuna 12, 50009 Zaragoza, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 May 2011
Received in revised form 13 September
2011
Accepted 16 September 2011
Available online 24 September 2011
Treatment of equimolar amounts of substituted aniline or amine with substituted benzaldehyde leads to
the corresponding achiral or chiral Schiff bases (L). The reaction of the bases with [Ag(O3SCF3)(PPh3)]
leads to the preparation of three or four coordinated cationic complexes, [Ag(k1-L)(PPh3)n]+ (n = 1 or 2)
which have been characterized by IR, 1D and 2D NMR spectroscopy. The crystal structure of [Ag{(S)-(6-
CH3)C5H3N-CHN-CꢀH(
a
-CH3)C6H5}(PPh3)2](O3SCF3) is reported.
Ó 2011 Elsevier B.V. All rights reserved.
Keywords:
Silver
Schiff bases
Nuclear magnetic resonance
1. Introduction
2. Experimental
The chemistry of silver(I) complexes has attracted an increased
interest during last years, due to both their structural features and
their potential applications. Silver(I) complexes with nitrogen li-
gands have proved to be valuable candidates in medicine, catalysis
or materials science. Polydentate ligands should offer different
coordination sites, thus dictating different coordination geometries
around the metal centre and the possibility to obtain monomeric
or polymeric species [1–27]. The use of Schiff bases as ligands
can increase the biological activity of many of their metallic coor-
dination complexes, i.e. as anti-influenza, antibacterial or as antitu-
moral agents [28–36]. Nevertheless, not many complexes of this
type have been described until now with silver(I) [37–46]. Among
them, different types of Schiff bases, e.g. containing heteroaromatic
benzimidazole and benzithiale rings [40], N,N chelating moieties
[41], cryptands [38] or other substituents, have been used as li-
gands in the silver(I) chemistry.
2.1. General
The starting complex [Ag(O3SCF3)(PPh3)] [47] and the Schiff
bases [48–52] were synthesized by similar procedures to those de-
scribed in literature. FT-IR spectra (KBr pellet) were obtained on a
model Vector-22 Bruker spectrophotometer. 1H, 19F, 31P{1H} and
13C{1H} NMR spectra were recorded on a Bruker AC-200P and
Bruker-400 spectrometers. Chemical shifts are reported in ppm rel-
ative to SiMe4 (1H, 13C) and 85% H3PO4 in D2O (31P) (positive shifts
downfield) as external standards, respectively. The values of the
coupling constants (1JC–H) of the ligands and complexes synthe-
sized were determined by means of the experiment of HMBC (2D
NMR).
2.2. Synthesis of the Schiff bases
Herein we describe the synthesis, characterization and reactiv-
ity of silver three or four coordinated complexes with the Schiff
bases shown in Fig. 1 as ligands.
The new Schiff bases used in this work (Fig. 1): O2NC6H4-
CHN-CH2C6H4(4-CH3) (L1), (CH3)2NC6H4-CHN-CH2C6H5 (L2),
(CH3)2NC6H4-CHN-CH2C6H4(4-CH3) (L3), C6H4N-CHN-CH2C6H5
(L4), C6H4N-CHN-CH2C6H4(4-Cl) (L5), C6H4N-CHN-CH2C6H4(4-CH3)
(L6), (S)-(ꢁ)-(6-CH3)C5H3N-CHN-CꢀH( -CH3)C6H5 (L7-ꢀCS) and
a
(S)-(ꢁ)-C5H4N-CHN-CꢀH( -CH3)C6H5 (L8-ꢀCS) were synthesized
a
⇑
by similar methods to those described in the bibliography [48–
Corresponding authors.
E-mail address: alaguna@unizar.es (A. Laguna).
52], by condensing equimolar amounts of different amines and
0020-1693/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2011.09.033

82
O. Cifuentes et al. / Inorganica Chimica Acta 379 (2011) 81–89
e
e
d
H
H
H
Monodentate achiral Schiff bases
f'
9'
Z = NO2, X = 12CH3h (L1)
c
6
7
b
4
g'
N
a
Z = N(1CH3 )2, X = Hh (L2)
3
2
8
9
5
10'
11
Z = N(1CH3 )2, X = 12CH3
)
3
a
h
4'
L
(
c'
f
3'
10
Z
X
b'
g
f
f
e
H
H
H
Bidentate achiral Schiff bases
g'
d
6
7
h'
4
9'
c
N
3
8
i
10'
11
X = Hi (L4); Cl (L5); 12CH3 (L6)
5
N
g9 10
b 2
1
X
a
h
g
e
13CH3
H
f
H
Bidentate chiral Schiff bases
h'
d
7
8
i'
5
10'
c
N
4
3
9
11'
12
6
N
Z = 1CH3a (L7-*CS); Ha (L8-*CS)
h10 11
j
b
2
i
Z
Fig. 1. Schiff bases L1–L8.
the respective substituted aldehydes, under continuous stirring.
Reaction times and temperature (room or refluxing temperature)
conditions are detailed below.
2.2.1.3. (CH3)2NC6H4-CHN-CH2C6H4(4-CH3) (L3). A solution of 4-
methylbenzylamine (200 mg, 1.65 mmol) and 4-(dimethyl-
amine)benzaldehyde (160 mg, 1.07 mmol) in 3 mL of ethanol was
stirred for 3 days at room temperature and protected from light.
Upon cooling a beige solid precipitated, which was filtered, washed
with cold ethanol and dried under vacuum. Yield, 66%. Anal. Calc.
for C17H20N2.0.75H2O (M = 264.87 g/mol): C, 77.09; H, 8.18; N,
10.58. Found: C, 77.26; H, 9.75; N, 10.24%. FT-IR:
2.2.1. Monodentate achiral Schiff bases (L1–L3)
2.2.1.1. O2NC6H4-CHN-CH2C6H4(4-CH3) (L1). A solution of 4-methyl-
benzylamine (1000 mg, 8.3 mmol), 4-nitrobenzaldehyde (1250 mg,
8.3 mmol) and glacial acetic acid (0.2 mL) in 3 mL of dichlorometh-
ane was stirred for 3 days at room temperature and protected from
light. The solution was evaporated under vacuum and the beige
residue washed with cold dichloromethane. Yield, 97%. FT-IR:
m
(C@N)im = 1634.7 cmꢁ1
.
1H NMR (acetone-d6): d 8.29 (s, 1Hd), 7.64
0
0
(d, 2Hc,c
,
3J = 8.8 Hz), 7.22 (d, 2Hf,f, 3J = 8.0 Hz), 7.13 (d, 2Hg´,g
,
3J = 8.0 Hz,), 6.75 (d, 2Hb,b
,
3J = 8.8 Hz), 4.67 (s, 2He), 3.00 (s, 6Ha),
0
2.30 (s, 3Hh). 13C{1H} NMR (acetone-d6): d 40.3 (C1, 1J = 140.3 Hz),
(C@N)im = 1638.2 cmꢁ1. Anal. Calc. for C15H14N2O2 (M = 254.29 g/
153.3 (C2), 112.5 (C3,3
, ,
1J = 155.8 Hz), 130.3 (C4,4 1J = 155.8 Hz);
m
0
0
125.9 (C5), 161.8 (C6, 1J = not resolved), 65.4 (C7, 1J = 131.2 Hz),
mol): C, 70.85; H, 5.55; N, 11.0. Found: C, 71.2; H, 5.8; N, 11.9%.
1H NMR (acetone-d6): d 8.60 (s, 1Hd), 8.29 (d, 2Hb,b 3J = 8.8 Hz,),
138.7 (C8), 128.7 (C9,9 , 1J = 154.2 Hz), 129,8 (C10 10
136.7 (C11), 21.2 (C12
1J = 124.4 Hz).
,
,
1J = 154.2 Hz),
0
0
0
3
3
0
0
8.05 (d, 2Hc,c, J = 8.8 Hz,), 7.25 (d, 2Hf,f , J = 8.0 Hz,), 7,16 (d, 2Hg,g
,
,
3J = 8.0 Hz,), 4.82 (s, 2He), 2.30 (d, 1Hh). 13C{1H} NMR (acetone-d6):
0
0
d 149.1 (C2), 123.7 (C3,3
, ,
1J = 173.5 Hz), 129.0 (C4,4 1J = 168.0 Hz),
2.2.2. Bidentate achiral Schiff bases (L4–L6)
142.1 (C5), 159.6 (C6, 1J = 162.8 Hz), 64.5 (C7, 1J = 135.4 Hz), 136.4
2.2.2.1. C5H4N-CHN-CH2C6H5 (L4). A solution of benzylamine
(200 mg, 1.87 mmol) and 2-pyridinecarboxaldehyde (200 mg,
1.87 mmol in 3 mL of water was stirred for 3 days at refluxing tem-
perature and protected from light. During this time it is observed the
formation of a yellow oil, which was isolated. Yield, 65%. Anal. Calc.
for C13H12N2.0.5H2O (M = 205.26 g/mol): C, 76.07; H, 6.38; N,
0
0
(C8), 128.0 (C9,9
(C11), 20.3 (C12
,
1J = 156.2 Hz), 128.9 (C10,10
1J = 125.0 Hz).
,
1J = 156.2 Hz), 136.3
,
2.2.1.2. (CH3)2NC6H4-CHN-CH2C6H5 (L2). A solution of benzylamine
(500 mg, 4.7 mmol) and 4-(dimethylamine)benzaldehyde (450 g,
3.0 mmol) in 3 mL of ethanol was stirred for 3 days at room tem-
perature and protected from light. Upon cooling a beige solid pre-
cipitated, which was filtered, washed with cold ethanol and dried
under vacuum. Yield, 41%. Anal. Calc. for C16H18N2 (M = 238.33 g/
mol): C, 80.63; H, 7.61; N, 11.75. Found: C, 79.64; H, 9.18; N,
13.65. Found: C, 76.92; H, 8.22; N, 13.50%. FT-IR: m(C@N)im = 1647.2,
m
(C@N)py = 1586.7 cmꢁ1 1H NMR (acetone-d6):
. d 8.65 (d, Hd,
3J = 4.8 Hz), 8.51 (s, He), 8.08 (d, Ha, 3J = 8.0 Hz), 7.83 (t, Hb,
3J = 8.0 Hz), 7.41 (dd, Hg,g
,
3J = 6.0 Hz, 4J = 1.2 Hz, 2H), 7.39 (t, Hc,
0
3
J = 6.4 Hz), 7.37 (t, Hh,h , 3J = 7.2 Hz, 2H), 7.27 (dt, Hi, 3J = 7.2 Hz,
4J = 1.2 Hz), 4.87 (s, Hf, 2H). 13C{1H} NMR (acetone-d6): d 121.4 (C1,
1J = 144.1 Hz), 137.3 (C2, 1J = 167.7 Hz), 125.8 (C3, 1J = 167.7 Hz),
150.3 (C4, 1J = 182.2 Hz), 155.8 (C5), 163.7 (C6, 1J = 165.3 Hz); 65.3
0
0
11.64%. FT-IR:
m
(C@N)im = 1638.6 cmꢁ1
.
1H NMR (acetone-d6): d
8.31 (s, 1Hd), 7.65 (d, 2Hc,c
,
,
3J = 9.0 Hz), 7.34 (dd, 2Hf,f
,
3J = 7.6 Hz,
0
0
4J = 1.6 Hz), 7.32 (t, 2Hg,g
3J = 7.6 Hz), 7.22 (dt, Hh, 3J = 7.6 Hz,
0
(C7, 1J = 135.6 Hz), 140.4 (C8), 129.0 (C9,9
,
1J = 160.2 Hz), 129.3
4J = 1.6 Hz), 6.75 (d, 2Hb,b
,
3J = 9.0 Hz), 4.71 (s, 2He), 3.00 (s, 6Ha).
0
(C10,10 , J = 160.2 Hz), 127.8 (C11, 1J = 156.5 Hz).
1
13C{1H} NMR (acetone-d6): d 40.3 (C1, 1J = 144.1 Hz), 153.3 (C2),
0
112.5 (C3,3 , ,
1J = 155.1 Hz), 130.4 (C4,4 1J = 155.1 Hz), 125.8 (C5),
0
0
162.1 (C6; 1J = not resolved), 65.5 (C7, 1J = 137.7 Hz), 141.8 (C8),
2.2.2.2. C5H4N-CHN-CH2C6H4(4-Cl) (L5). Following a procedure sim-
ilar to the reported for L4, from a solution of 4-chlorobenzylamine
(200 mg, 1.41 mmol) and 2-pyridinecarboxaldehyde (370 mg,
0
0
128.8 (C9,9
,
1J = 158.8 Hz), 129.1(C10,10 ; 1J = 158.8 Hz), 127.4 (C11
,
1J = 155.1 Hz).

O. Cifuentes et al. / Inorganica Chimica Acta 379 (2011) 81–89
83
3.45 mmol) a yellow oil was isolated. Yield, 76%. Anal. Calc. for
13H11N2Cl (M = 230.69 g/mol): C, 67.68; H, 4.81; N, 12.14.
Found: C, 67.74; H, 6.05; N, 12.25%. FT-IR: (C@N)im = 1650.4,
2.3. Synthesis of the silver(I) complexes
C
m
2.3.1. Synthesis of complexes with monodentate achiral Schiff bases
To a saturated solution of the complex [Ag(O3SCF3)(PPh3)]
(100 mg, 0.19 mmol) in dichloromethane, a stoichiometric amount
of the respective Schiff base (49.2 mg, 0.19 mmol, L1), (45.0 mg,
0.19 mmol, L2) or (48.8 mg, 0.19 mmol, L3) was added in 3 mL of
dichloromethane. The mixture was stirred for 45 min at room tem-
perature protected from light. The metallic silver obtained was fil-
tered off through Kieselguhr and the solution was concentrated
under reduced pressure to a small volume (2 mL) and the com-
plexes precipitated by addition of diethyl ether.
m
(C@N)py = 1586.8 cmꢁ1 1H NMR, (CDCl3): d 8.62 (d, Hd, 3J = 4.4 Hz,
;
1H); 8.47 (s, He, 1H); 8.03 (d; Ha, 3J = 8.0 Hz, 1H); 7.68 (dt, Hb,
3J = 7.6 Hz; 4J = 1.2 Hz, H); 7.27(m, Hg,g ; Hh,h ; Hc, 5H); 4.78 (s,
Hf, 2H).13C{1H} NMR (CDCl3) d 121.3 (C1, J = 166.7 Hz); 136.5 (C2;
1J = 163.4 Hz); 124.9 (C3; 1J = 164.4 Hz); 149.4 (C4; 1J = 179.0 Hz);
154.4 (C5); 163.1 (C6, 1J = 161.9 Hz); 64.0 (C7, 1J = 144.2 Hz);
1
0
0
0
0
132.8 (C8); 128.6 (C9,9
,
1J = 165.9 Hz); 129.4 (C10,10
,
1J = 161.0 Hz); 137.4 (C11).
The white solids of [Ag(j -
1-L1)(PPh3)](O3SCF3) (1) and [Ag(j1
Ln)(PPh3)2](O3SCF3) [Ln = L2 (2) and L3 (3)] were filtered, washed
with diethyl ether (3 ꢃ 5 mL) and dried under vacuum.
2.2.2.3. C5H4N-CHN-CH2C6H4(4-CH3) (L6). Following a procedure
similar to the reported for L4, from a solution of hot 4-methylben-
zylamine (230 mg, 1.9 mmol) and 2-pyridinecarboxaldehyde
(230 mg, 2.15 mmol) a yellow oil was isolated. Yield, 74%. Anal.
Calc. for C14H14N2ꢂH2O (M = 228.29 g/mol): C, 73.66; H, 7.06; N,
2.3.1.1. [Ag{
33%. Thermolabile solid; FT-IR:
and 636, s(CF3) = 1274, as(CF3) = 1153,
and 514 cmꢁ1. 1H NMR (acetone-d6): d 8.91 (s, Hd, 1H), 8.11 [AB (HA(b,b )
j
1-O2NC6H4-CHN-CH2C6H4(4-CH3)}(PPh3)](O3SCF3) (1). Yield,
(C@N)im = 1596.7, PPh3 = 1094, 745, 694
s(SO3) = 1029 and d(CF3) = 572
m
m
12.27. Found: C, 70.76; H, 6.98; N, 11.79%. FT-IR: (C@N)im = 1647.5,
m
(C@N)py = 1603.0 cmꢁ1 1H NMR (acetone-d6):
.
d 8.65 (d, Hd,
m
m
v
m
0
3J = 4.8 Hz, 1H), 8.50 (s, He, 1H), 8.08 (d, Ha, 3J = 8.0 Hz, 1H), 7.79
,
0
(dt, Hb, Jbc = 7,8 Hz, 4J = 1.2 Hz, 1H), 7.37 (ddd, Hc, 3J = 4.8 Hz,
3
HB(c,c )) system,
m
0 = 3244.65 Hz. JAB = 6.0 Hz,
Dm
= 12.06 Hz, 4H], 7.45–
3
0
0
3J = 7,6 Hz, 4J = 1.2 Hz, 1H), 7,27 (d, Hg,g
Hh,h
NMR (acetone-d6):
,
3J = 8.0 Hz, 2H), 7.16 (d,
7.33 (m, PPh3, 15H), 7.31 (d, Hf,f , 2H, Jfg = 7.9 Hz), 6.99 (d, Hg,g , 2H,
3Jgf = 7.9 Hz), 4.86 (s, He, 2H), 2.75 (s, Hh, 3H). 31P{1H} NMR (acetone-
d6, room temperature): d 12.8 (br). 19F NMR (acetone-d6): d ꢁ79.87 (s).
0
,
3J = 8.0 Hz, 2H), 4.82 (s, Hf, 2H), 2.30 (s, Hi, 3H). 13C{1H}
0
d
121.4 (C1, 1J = 167.0 Hz), 136.5 (C2,
1J = 163.6 Hz), 125.6 (C3, 1J = 165.4 Hz), 150.2 (C4, 1J = 180.6 Hz),
155.8 (C5), 163.4 (C6, 1J = 162.5 Hz), 65.0 (C7, 1J = 135.4 Hz), 137.2
2.3.1.2. [Ag{
34%. Thermolabile solid. FT-IR:
j
1-(CH3)2NC6H4-CHN-CH2C6H5}(PPh3)2](O3SCF3) (2). Yield,
(C@N)im = 1604.9, PPh3 = 1095, 745,
, ,
1J = 159.7 Hz), 129.9 (C10,10 1J = 156.2 Hz),
m
m
0
0
(C8, C11), 128.9 (C9,9
21.2 (C12
1J = 124.1 Hz).
695 and 637,
ms(CF3) = 1274, ms(CF3) = 1168, mas(SO3) = 1031 and
,
d(CF3) = 60, 573 and 517 cmꢁ1
.
1H NMR (acetone-d6): d 8.77 (s, Hd,
3
Jcb = 9.0 Hz, 2H), 7.56 (d, Hf,f , 3J = 7.6 Hz, 2H),
0
0
1H), 7.83 (d, Hc,c
,
2.2.3. Bidentate chiral Schiff bases (L7-ꢀCs; L8-ꢀCs)
2.2.3.1. (S)-(ꢁ)-(6-CH3)C5H3N-CHN-CꢀH( -CH3)C6H5 (L7-ꢀCS). Fol-
lowing a procedure similar to the reported for L4, from a hot solu-
tion of (S)-(ꢁ)- -methylbenzylamine (100 mg, 0.83 mmol) and 6-
methylpyridine-2-carboxaldehyde (101 mg, 0.83 mmol) a orange
oil was isolated. Yield, 40%. Anal. Calc. for 15H16N2.2.5H2O
(M = 269.34 g/mol): C, 66.90; H, 7.86; N, 10.40. Found: C, 67.02;
7.53 (vt, Hpara, PPh3, 6H), 7.40 (vt, Hmeta, PPh3, 12H), 7.29 (vt, Hortho
,
a
0
PPh3, 2Hg, Hh, 15H), 6.50 (d, Hb,b , 2H), 4.84 (s, He, 2H), 2.97 (s, Ha,
6H). 13C{1H} NMR (acetone-d6): d 40.3 (C1, 1J = 138.5 Hz), 153.9
(C2), 112.7 (C3,3 , ,
1J = 164.1 Hz), 129.6 (C4,4 1J = 151.0 Hz), 122.0
a
0
0
(C5), 166.2 (C6, 1J = 161.5 Hz), 66.2 (C7, 1J = 134.6 Hz), 140.4 (C8),
1J = not resolved), 129.2 (C10,10
,
1J = 157.6 Hz), 128.6
C
0
0
130.7 (C9,9
(C11
1J = 151.0 Hz), 130.3 (Cmeta
132.0 (Cpara
,
3
,
,
1J = 168.1 Hz, JPC = 19.7 Hz, PPh3),
H, 9.17; N, 10.90%. FT-IR:
m
(C@N)im = 1646.6,
m
(C@N)py = 1590.7 cmꢁ1
.
4
,
1J = 177.3 Hz, JPC = not resolved, PPh3), 134.7 (Cortho
,
1H NMR (acetone-d6): d 8.42 (s, 1He, 1H), 7.91 (d, Hd, 3J = 7.6 Hz, 1H),
2
1J = 173.3 Hz, JPC = 31.7 Hz, PPh3). 31P{1H} NMR (acetone-d6, room
7.71 (t, Hc, 3J = 8.0 Hz, 1H), 7.47 (d, Hh,h , J = 7,2 Hz, 2H), 7.34 (t, Hi,i
,
3
0
0
temperature): d 9.9 (br): 19F NMR (acetone-d6): d ꢁ76.9 (s).
3J = 7.2 Hz, 2H), 7.26 (d, Hb, 3J = 8.0 Hz, 1H), 7.24 (t, Hj, 3J = 7.2 Hz,
1H), 4.66 (q, Hf, 3J = 6.8 Hz, 1H), 2.52 (s, Ha, 3H), 1.55 (d, Hg,
2.3.1.3. [Ag{
(3). Yield, 38%. Thermolabile solid. FT-IR:
j
1-(CH3)2NC6H4-CHN-CH2C6H4(4-CH3)}(PPh3)2](O3SCF3)
(C@N)im = 1596.91,
as(CF3) = 1164,
1H NMR (ace-
3J = 6.8 Hz, 3H). 13C{1H} NMR (acetone-d6):
d
24.4 (C1,
m
1J = 127.5 Hz), 154.4 (C2), 125.0 (C3, 1J = 162.1 Hz), 137.6 (C4,
m
m
PPh3 = 1097, 747, 694 and 637, ms(CF3) = 1275, m
1J = 161.8 Hz), 118.6 (C5, 1J = 166.7 Hz), 157.9 (C6), 161.7 (C7,
s(SO3) = 1030 and d(CF3) = 573, 517 and 503 cmꢁ1
.
1J = 160.8 Hz), 70.2 (C8, 1J = 137.3 Hz), 146.2 (C9), 127.5 (C10,10
,
,
0
3Jcb = 8.9 Hz, 2H), 7.55
0
tone-d6): d 8.68 (s, Hd, 1H), 7.75 (d, Hc,c
,
1J = 155.6 Hz), 129.3 (C11,11
,
1J = 155.6 Hz), 127.7 (C12
0
(vt, Hpara, PPh3, 6H), 7.41 (vt, Hortho, PPh3, 12H), 7.28 (vt, Hmeta
,
1J = 155.6 Hz), 25.4 (C13
,
1J = 127.5 Hz).
3
0
0
PPh3, 12H), 7.11 (d, Hf,f
, Jfg = 8.0 Hz, 2H), 6.94 (d, Hg,g , 2H), 6.53
0
(d, Hb,b , 2H), 4.74 (s, He, 2H), 2.98 (s, Ha, 6H), 2.22 (s, Hh, 3H).
2.2.3.2. (S)-(ꢁ)-C5H4N-CHN-CꢀH(
procedure similar to the reported for L4, from a solution of (S)-
-methylbenzylamine (100 mg, 0.83 mmol) and 2-pyridine-
carboxaldehyde (95 mg, 0.89 mmol) a orange oil was isolated.
Yield, 42%. Anal. Calc. for C14H14N2ꢂ2H2O (M = 246.3 g/mol): C,
68.27; H, 5.73; N, 11.37. Found: C, 68.08; H, 6.05; N, 11.38%. FT-
a
-CH3)C6H5 (L8-ꢀCS). Following a
13C{1H}NMR (acetone-d6): d 48.2 (C1, 1J = 137.3 Hz), 151.9 (C2),
112.6 (C3,3
, , ;
1J = 152.9 Hz), 129.3 (C4,4 1J = 164.6 Hz, C10,10
0
0
0
(ꢁ)-a
1J = 149.3 Hz), 122.3 (C5), 164.5 (C6, 1J = 160.8 Hz), 65.8 (C7,
1J = 131.4 Hz); (C8, C9,9 and C11 not resolved), 23.0 (C12
,
0
1J = 127.5 Hz), 130.3 (Cmeta
,
1J = 160.8 Hz; JPC = 19.7 Hz, PPh3);
3
4
132.0 (Cpara
,
1J = 168.5, JPC = not resolved, PPh3), 134.7 (Cortho
,
2
IR:
m
(C@N)im = 1647.0,
m
(C@N)py = 1586.7 cmꢁ1
.
1H NMR (acetone-
1J = 164.6 Hz, JPC = 31.5 Hz, PPh3), 130.6 (Cipso
,
1JPC = 61.2 Hz,
d6): d 8.64 (d, Hd, 3J = 4.8 Hz, 1H), 8.50 (s, He, 1H), 8.12 (d, Ha,
PPh3). 31P{1H} NMR (acetone-d6, room temperature): d 10.8 (br).
19F NMR (acetone-d6): d ꢁ76.86 (s).
3J = 8.0 Hz, 1H), 7.82 (dt, Hb, 3J = 7.6 Hz, 4J = 1.2 Hz, 1H), 7.49 (d,
3J = 7,6 Hz, 2H), 7.39 (ddd, Hc, 3J = 8.0 Hz, 3J = 4.8 Hz;
0
Hh,h
,
4J = 1.2 Hz, 1H), 7.35 (t, Hi,i
,
3J = 7,6 Hz, 2H), 7.24 (t, Hj, 3J = 7.6 Hz,
2.3.2. Synthesis of silver(I) complexes with bidentate achiral Schiff
bases
0
1H), 4.68 (q, Hf, 3J = 6.8 Hz, 1H), 1.56 (d, Hg, 3J = 6.8 Hz, 3H).
13C{1H} NMR (acetone-d6): d 121.5 (C2, 1J = 166.9 Hz), 137.5 (C3,
1J = 165.0 Hz), 125.7 (C4, 1J = 164.8 Hz), 150.2 (C5, 1J = 181.9 Hz),
155.9 (C6), 161.4 (C7, 1J = 163.2 Hz), 70.1 (C8, 1J = 135.2 Hz), 146.0
To a saturated solution of the complex [Ag(O3SCF3)(PPh3)]
(150 mg; 0.29 mmol) in dichloromethane (20 mL), a stoichiometric
amount of the respective Schiff base (37.6 mg, 0.19 mmol, L4),
(44.3 mg, 0.19 mmol, L5) or (40.3 mg, 0.19 mmol, L6) was added.
The heterogeneous mixture was stirred at room temperature for
1J = 155.7 Hz), 129.2 (C11,11
1J = 126.7 Hz).
,
1J = 155.7 Hz),
0
0
(C9), 127.5 (C10,10
127.7 (C12
,
,
1J = 156.0 Hz), 25.4 (C13
,

84
O. Cifuentes et al. / Inorganica Chimica Acta 379 (2011) 81–89
4
1 h protected from light. The metallic silver obtained was filtered
off through Kieselguhr and the solutions were concentrated under
reduced pressure to a small volume (3 mL) and the complexes
precipitated by addition of diethyl ether. The white solids of
3JPC = 19.3 Hz, PPh3), 131.7 (Cpara 1J = 157.5 Hz, JPC = not resolved,
,
PPh3), 134.5 (Cortho, ,
1J = 167.3, JPC = 32.3 Hz, PPh3), 132.8 (Cipso
2
1JPC = 59.6 Hz, PPh3). 31P{1H} NMR (acetone-d6, room temperature):
d 9.2 (br). 19F NMR (acetone-d6): d ꢁ76.86 (s).
[Ag(j
2-Ln)(PPh3)2](O3SCF3) [Ln = L4 (4), L5 (5) and L6 (6) and L7
(7)] were filtered, washed with diethyl ether (3 ꢃ 5 mL) and dried
2.3.3. Synthesis of silver(I) complexes with bidentate chiral Schiff bases
To a saturated solution of the complex [Ag(O3SCF3)(PPh3)]
(150 mg, 0.288 mmol) in dichloromethane (20 mL), a stoichiome-
tric amount of the Schiff base Ln-ꢀCs [0.10 mmol, 21.0 mg (n = 7),
59.9 mg (n = 8)] was added. The heterogeneous mixture was stir-
red at room temperature for 1 h (7) or 15 min (8) and protected
from light. The metallic silver obtained was filtered off through
Kieselguhr and the solution concentrated under reduced pressure
to a small volume (3 mL). Upon addition of diethyl ether (10 mL)
a white solid of 7 or 8 was filtered, washed with diethyl ether
(3 ꢃ 5 mL) and dried under vacuum.
under vacuum.
2.3.2.1. [Ag{j
2-C5H4N-CHN-CH2C6H5}(PPh3)2](O3SCF3) (4). Yield,
50%. Anal. Calc. for C50H42AgF3N2O3P2S (M = 977.77 g/mol): C,
61.42; H, 4.33; N, 2.86; S, 3.28. Found: C, 60.96; H, 4.35; N, 3.01;
S, 3.12%. FT-IR:
782, 745, 694 and 637,
and d(CF3) = 572 and 516 cmꢁ1
m
(C@N)py = 1602.1,
m
(C@N)im = 1589.6,
as(CF3) = 1153,
1H NMR (acetone-d6): d 9.07 (s,
m
PPh3 = 1096,
m
s(CF3) = 1275,
m
ms(SO3) = 1031
.
He, 1H), 8.73 (d, Hd, 3J = 4.8 Hz, 1H), 8.22 (dd, Ha, 3J = 7.2 Hz,
4J = 1.6 Hz, 1H), 8.19 (t, Hb, 3J = 7.2 Hz, 1H), 7.67 (ddd, Hc,
3J = 7.2 Hz, 3J = 4.8 Hz, 4J = 1.6 Hz, 1H), 7.49 (vt, Hpara, PPh3, 6H),
0
0
7.37–7.28 [m, Hmeta, Hortho (PPh3), Hg,g , Hh,h , Hi, 29H], 7.23 (d, Hf,
2.3.3.1. [Ag(k2-L7-ꢀCs)(PPh3)2](O3SCF3) (7). Yield, 25%. Anal. Calc. for
JHP = 1.2 Hz), 7.21 (d, Hff , JHP = 2.0 Hz). 13C{1H} NMR (acetone-
4
4
0
C52H46AgF3N2O3P2S (M = 1005.82 g/mol): C, 62.10; H, 4.61; N, 2.79;
d6): d 123.1 (C1, 1J = not resolved), 140.2 (C2, 1J = not resolved),
126.4 (C3, 1J = not resolved), 152.2 (C4, 1J = not resolved), 157.1
(C5), 161.7 (C6, 1J = not resolved) (C7, it is probably overlapped with
the signals of the carbons of the phenyls groups of PPh3), 142.3
S, 3.19. Found: C, 61.27; H, 3.92; N, 2.86; S, 4.38%. FT-IR:
(C@N)py = 1645.9, (C@N)im = 1591.3, PPh3 = 1092, 794, 765, 699
as(CF3) = 1155, s(SO3) = 1032 and
m
m
m
and 638,
m
s(CF3) = 1276,
m
m
d(CF3) = 572, 540 and 516 cmꢁ1
.
1H NMR (acetone-d6): d 8.81 (d,
1
1
0
0
(C8), 129.2 (C9,9 , J = not resolved), 130.5 (C10,10 , J = not resolved),
4
1He, JPH = 0.8 Hz, 1H), 7.94 (br, Hd, 1H), 7.61 (t, Hc, 3J = 7.6 Hz,
128.8 (C11
,
1J = not resolved), 130.2 (Cmeta
,
1J = 163.3 Hz,
1H), 7.57 (d, Hb, 3J = 7.6 Hz, 1H), 7.52 (vt, Hpara, PPh3, 5H), 7.39
3JPC = 12.3 Hz, PPh3), 131.8 (Cpara
,
1J = 159.9 Hz, JPC = not resolved,
4
0
0
(vt, Hmeta, PPh3, 10H); 7.33–7.09 (m, PPh3, Hh,h , Hi,i , Hj, 20H),
4.84 (q, Hf, 3J = 6.4 Hz, 1H), 2.22 (s, Ha, 3H), 1.42 (d, Hg,
3J = 6.4 Hz, 3H). 13C{1H} NMR (acetone-d6): d 24.7 (C1, 1J = not re-
solved), (C2, not resolved), 126.8 (C3; 1J not resolved), 137.9 (C4,
3J = 164.6 Hz), 121.9 (C5, 3J = 170.0 Hz), 158.2 (C6), 162.5 (C7,
1J = not resolved), (C8; 1J = not resolved), (C9, not resolved); 128.6
PPh3), 134.5 (Cortho, ,
1J = 56.2 Hz, JPC = 32.5 Hz, PPh3), 132.7 (Cipso
2
1JPC = 55.4 Hz, PPh3). 31P{1H} NMR (acetone-d6, room temperature):
d 10.8 (br). 19F NMR (acetone-d6): d ꢁ76.86 (s).
2.3.2.2. [Ag{j
2-C5H4N-CHN-CH2C6H4(4-Cl)}(PPh3)2](O3SCF3) (5). Yield,
48.4%. Anal. Calc. for C50H41AgClF3N2O3P2S (M = 1012.21 g/mol): C,
59.33; H, 4.08; N, 2.77; S, 3.17. Found: C, 60.01; H, 4.31; N, 3.76;
(C10,10
,
1J = 164.6 Hz), 127.0 (C11,11
1J = not resolved), 129.2 (Cmeta
1J = 167.8 Hz, JPC = 19.0 Hz, PPh3), 130.7 (Cpara 1J = 157.0 Hz,
,
1J = 162.4 Hz), 140.4 (C12,
0
0
1J = not resolved), 23.9 (C13
,
,
S, 3.22%. FT-IR:
m(C@N)py = 1642.4,
m
(C@N)im = 1589.2, PPh3 = 1095,
m
3
,
779, 744, 694 and 632,
ms(CF3) = 1265,
m
as(CF3) = 1151, ms(SO3) = 1031
2
4JPC = not resolved, PPh3), 133.5 (Cortho
,
1J = 163.5, JPC = 32.1 Hz,
and d(CF3) = 572, 516 and 505 cmꢁ1 1H NMR (acetone-d6): d 8.96
.
PPh3), 132.0 (Cipso
,
1JPC = 50.8 Hz, PPh3). 31P{1H} NMR (acetone-d6,
(s, He, 1H), 8.42 (d, Hd, 3J = 4.4 Hz, 1H), 8.12 (t, Hb, 3J = 7.6 Hz, 1H),
8.07 (dd, Ha, 3J = 7.6 Hz, 4J = 0.8 Hz, 1H), 7.57–7.55 (m, Hc, 1H),
room temperature): d 5.4 (br). 19F NMR (acetone-d6): d ꢁ71.4 (s).
7.52 (vt, Hpara, PPh3, 6H), 7.40 (vt, Hmeta, PPh3, 12H), 7.19 (m, Hortho
,
2.3.3.2. [Ag(k2-L8-ꢀCs)(PPh3)](O3SCF3) (8). Yield, 32.3%. Thermola-
PPh3, Hg,g , 14H), 7.00 (d, Hh,h ,
3J = 8.0 Hz, 2H), 4.83 (s, Hf,f , 2H).
0
0
0
13C{1H} NMR (acetone-d6): d 126.6 (C1, 1J = 167.3 Hz), 139.7 (C2,
1J = 161.5 Hz), 128.1 (C3, 1J = not resolved), 151.5 (C4, 1J = not re-
solved), (C5, not resolved), 165.0 (C6, 1J = not resolved), 64.5 (C7;
0
bile solid. FT-IR:
747, 695 and 637,
d(CF3) = 572, 517 and 505 cmꢁ1
m
(C@N)py = 1640.2,
s(CF3) = 1263, as(CF3) = 1152,
1H NMR (acetone-d6): d 9.45 (s,
m
(C@N)im = 1591.2,
mPPh3 = 1096,
m
m
ms(SO3) = 1030, and
.
He, 1H), 9.05 (d, Hd, 3J = 4.4 Hz, 1H), 8.60 (dt, Hb, 3J = 7.6 Hz,
4J = 1.6 Hz, 1H), 8.46 (d, Ha, 3J = 7.6 Hz, 1H), 8.14 (ddd, Hc,
3J = 7.6 Hz, 3J = 4.4 Hz, 4J = 1.6 Hz, 1H), 7.95 (vdt, Hpara, PPh3, 2H),
7.87 (vdt, Hpara, Hmeta, PPh3, 5H), 7.75 (m, Hmeta, Hortho, PPh3, 8H),
1J = 132.2 Hz), 139.6 (C8), 129.7 (C9,9
,
1J = not resolved), 131.2
1J = not resolved), 140.3 (C11), 130.2 (Cmeta
,
1J = 157.4 Hz,
0
(C10,10
,
3JPC = 19.1 Hz, PPh3), 131.7 (Cpara
,
1J = 160.0 Hz, JPC = not resolved,
4
2
PPh3), 134.4 (Cortho
,
1J = not resolved, JPC = 32.9 Hz, PPh3), 133.0
7.53 (m, Hh,h , Hi,i , Hj, 5H), 5.49 (q, Hf, 3J = 6.4 Hz, 1H), 2.04 (d, Hg,
3J = 6.4 Hz, 3H). 31P{1H} NMR (acetone-d6, room temperature): d
14.4 (br). 19F NMR (acetone-d6): d ꢁ80.0 (s).
(Cipso, 1JPC = 52.8 Hz, PPh3). 31P{1H} NMR (acetone-d6, room temper-
ature): d 10.8 (br). 19F NMR (acetone-d6): d ꢁ76.86 (s).
0
0
2.3.2.3. [Ag{j
2-C5H4N-CHN-CH2C6H4(4-CH3)}(PPh3)2](O3SCF3) (6). Yield,
44.2%. Anal. Calc. for C51H44AgF3N2O3P2S (M = 991.79 g/mol): C,
2.4. Crystal structure determination
61.76; H, 4.47; N, 2.82; S, 3.23. Found: C, 61.43; H, 4.60; N, 2.75; S,
2.98%. FT-IR:
m(C@N)py = 1640.8,
m(C@N)im = 1589.5,
mPPh3 = 1095, 779,
Suitable crystals for X-ray diffraction of [Ag(k2-(S)-(ꢁ)-(6-
746, 695 and 637,
m
s(CF3) = 1272,
m
as(CF3) = 1149,
m
s(SO3) = 1031 and
CH3)C5H3N-CHN-CꢀH(
a-CH3)(C6H5)(PPh3)2](O3SCF3)
(7)
were
d(CF3) = 573, 516 and 506 cmꢁ1
.
1H NMR (acetone-d6): d 8.99 (s, He,
grown by slow diffusion of diethyl ether into a dichloromethane
solution of the complex. The crystal was mounted in inert oil on
glass fibers and transferred to the cold gas stream of Xcalibur
Oxford Diffraction diffractometer equipped with a low-tempera-
ture attachment. Data were collected using monochromated Mo
1H), 8.34 (d, Hd, 3J = 4.8 Hz, 1H), 8.15 (dt, Hb, 3J = 7.6 Hz, 4J = 1.6 Hz,
1H), 8.05 (d, Ha, 3J = 7.6 Hz, 1H), 7.55 (ddd, Hc, 3J = 4.8 Hz,
3J = 7.6 Hz, 4J = 1.2 Hz, 1H), 7.51 (vt, Hpara, PPh3, 6H), 7.39 (vt, Hmeta
,
PPh3, 12H), 7.18 (vt; Hortho, PPh3, 12H), 6.97 (d, Hg,g ,
3Jgh = 8.0 Hz,
0
2H), 6.76 (d, Hh,h , 2H), 4.78 (s, Hf,f , 2H), 2.13 (s, Hi, 3H). 13C{1H}
NMR (acetone-d6): d (C1, not resolved), 138.5 (C2, 1J = not resolved),
128.6 (C3, 1J = not resolved), 152.4 (C4, 1J = not resolved), (C5, not re-
solved), 164.3 (C6, 1J = not resolved), 64.6 (C7, 3J = 137.8 Hz), 140.3
K
a
radiation (k = 0.71073 Å), scan type x. Absorption corrections
0
0
based on multiple scans were applied with the program SADABS
[53]. The structure was refined on F2 using the program SHELXL-97
[54]. All non-hydrogen atoms were refined anisotropically. Hydro-
gen atoms were included using a riding model. Further details of
the data collection and refinement are given in Table 1.
0
0
(C8), 129.7 (C9,9
,
1J = not resolved); 130.4 (C10,10
,
1J = not resolved),
1J = 163.4 Hz,
140.4 (C11), 21.3 (C12
,
3J = 124.0 Hz), 130.1 (Cmeta
,

O. Cifuentes et al. / Inorganica Chimica Acta 379 (2011) 81–89
85
Table 1
(He), respectively. The ligands L2 and L3 also exhibit a singlet at
3.00 ppm, assigned to the dimethylamino group. L1 and L3 show
a signal at 2.30 ppm, assigned to the protons of the methyl group.
The 13C{1H}, Dept., HSQC and HMBC spectra allow the assign-
ment of most of the carbon atoms of the synthesized ligands. With
the help of the HMBC experiment, the correlation between a
hydrogen atom with the different carbon atoms (at two to three
bonds) and their respective coupling constants may be studied.
The HMBC spectrum of the ligand L3 is shown in Table 2.
Crystallographic data and information about data collection and refinement for 7.
Compound
7
Formula
Formula weight
T (K)
Crystal system
Space group
Unit cell dimensions
a (Å)
C52 H46Ag F3N2O3P2S
1005.78
100(2) K
Monoclinic
P2(1)
15.158(3)
14.525(3)
22.028(4)
90
b(Å)
c (Å)
3.1.2. Bidentate achiral Schiff bases (L4–L6)
a
(°)
b (°)
104.15(3)
90
4702.8(16)
4
1.421
0.598
The Schiff bases L4–L6 (Fig. 1) are obtained as yellow oils from
the reaction of 2-pyridinecarboxaldehyde with the respective
substituted amines. Infrared spectra show a characteristic intense
band in the range 1650.2–1638.1 cmꢁ1, which is attributed to the
c
(°)
V (Å3)
Z
Density (calculated, Mg mꢁ3
)
(mmꢁ1
)
m
(C@N)im vibrations, and a band in the range 1586.7–1603 cmꢁ1, as-
l
signed to the m(C@N)py vibrations [60,61]. The 1H NMR [62–64],
13C{1H}, Dept., HSQC and HMBC spectra allow the assignment of
most of the different carbon atoms and their respective coupling
constants (Section 2).
F(000)
2064
Crystal size (mm3)
0.13 ꢃ 0.11 ꢃ 0.10
4.08–25.00
134246/16391
0.0300
h (°)
Reflections:collected/independent
Rint
Maximum and minimum transmission
Data/restraints/parameters
Goodness-of-fit on (GOF) on F2
Absolute structure parameter
wR (F2, all reflections)
0.9426, 0.9263
16391/4/1159
1.035
0.018(16)
0.0795
3.1.3. Bidentate chiral Schiff bases (L7-ꢀCS and L8-ꢀCS)
The ligands L7-ꢀCS and L8-ꢀCS (Fig. 1) are prepared by reaction
between the respective aldehydes and optically pure (S)-(ꢁ)-
a-
R(I > 2
Maximum
r
(I))
0.0338
1.352
methylbenzylamine. They are obtained as orange oils. The FT-IR
v
(e Åꢁ3
)
spectra exhibit characteristic intense bands at 1646.6 and
1647.0 cmꢁ1, respectively, due to the
m(C@N) vibrations of the iminic
(C@N) group. Another band at 1590.7 and 1586.7 cmꢁ1, respec-
tively is assigned to the m(C@N)py vibrations of the pyridinic (C@N)
group [79]. The 1H NMR spectra are reported in the Experimental
Section.
3. Results and discussion
3.1. Synthesis and characterization of the Schiff bases
The Schiff bases are synthesized according to a general proce-
dure that consists on the condensation of equimolar amounts of
substituted aniline or amine and the respective substituted benzal-
dehyde, in the presence of magnesium sulfate as a dehydrating
agent, in some cases. The synthesized Schiff bases were character-
ized by FT-IR, and one and two-dimensional NMR spectroscopy.
3.2. Synthesis and characterization of the silver(I) complexes (1–8)
with achiral and chiral Schiff bases
Reaction of [Ag(O3SCF3)(PPh3)] with the corresponding Schiff
base leads to the synthesis of complexes of stoichiometry [Ag(j1
-
L)(PPh3)n](O3SCF3) (n = 1 or 2) (1–8), which were isolated as solids.
Complexes 1–8 were characterized by FT-IR and one- (1H, 13C{1H},
31P{1H} or 19F) and two-dimensional NMR spectroscopy (1H–1H
COSY, HSQC, HMBC or NOESY).[65–67]
3.1.1. Monodentate achiral Schiff bases (L1–L3)
The monodentate ligands (L1–L3) are represented in the Fig. 1.
The infrared spectra of the Schiff bases (L1–L3) show an intense
band in the range of 1634.7–1638.6 cmꢁ1 corresponding to the
The FT-IR spectra of complexes 1–8 include the characteristic
bands of the triphenylphosphine (1092–1091, 745–744, 695–670,
571–540 and 501 cmꢁ1) and the triflate anion (
msym(CF3) = 1276–
m
(C@N) vibrations [55,56]. The 1H NMR spectra show two singlet res-
1267, masym(CF3) = 1155–1143, msym(SO3) = 1032–1031, d(CF3) = 638–
onances at the ranges 4.82–4.67 and 8.60–8.26 ppm [57–59]
attributed to the iminic proton (Hd) and the methylene protons
637, 573–572 and 516–511 cmꢁ1) [68]. Also, the corresponding
stretching vibrations m(C@N) of the iminic and/or pyridinic groups
(4–8) of the Schiff free bases (L1–L8), modify their values due to
the coordination to the metallic center. They appear in the range
1589–1605 or 1602–1646 cmꢁ1 (4–8), respectively.
Table 2
Correlation between hydrogen atoms with different
carbon atoms (at two to three bonds). The coupling
constants (1JCH) are reported in the Section 2.
3.2.1. Silver(I) complexes with monodentate achiral Schiff bases (1–3)
The reaction of [Ag(O3SCF3)(PPh3)] with the monodentate Schiff
bases L1–L3 in molar ratio 1:1 leads to the cationic complexes
Schiff base Carbon–proton atoms
L3
(C7-Hd) – three bonds
(C4-Hd) – three bonds
(C5-Hd) – two bonds
[Ag(j
1-L)(PPh3)n](O3SCF3), where n = 1, L = L1 (1); n = 2, L = L2 (2)
or L3 (3), with one or two PPh3 groups, in agreement with the 1H
NMR spectra.
(C2-Hc) – three bonds
(C6-Hc and He) – three bonds(both)
(C3-Hc) – two bonds
(C9-He) – three bonds
(C6-He) – three bonds
(C2-Ha) – two bonds
(C10-Hh) – three bonds
(C11-Hh) – two bonds
(C3-Ha) – three bonds
The FT-IR spectra of the complexes (1–3) show the character-
istic strong absorption of m(C@N)im at 1596.7, 1604.9 and
1596.9 cmꢁ1, respectively. These bands appear at lower energy
than those for the corresponding free ligand (1638.3 (L1),
1633.4 (L2) and 1623.1 (L3) cmꢁ1) [69,70]. This suggests that
the iminic nitrogen (Schiff base) is coordinated to the silver(I).
The 1H NMR spectrum of complex
1 shows a singlet at

86
O. Cifuentes et al. / Inorganica Chimica Acta 379 (2011) 81–89
Fig. 2. 1H NMR spectrum of complex 3 in acetone-d6.
Fig. 3. The HMBC experiment of complex 3.
4.86 ppm attributed to the methylene protons (He). At low field it
shows a singlet at 8.91 ppm, assigned to the iminic proton (Hd).
present displacement to low field and strong displacement to
high field, respectively, which indicates the coordination of the
iminic nitrogen to the metallic center.
0
0
0
The resonances of the protons Hd, Hc,c, and Hf,f and, Hb,b and Hg,g

O. Cifuentes et al. / Inorganica Chimica Acta 379 (2011) 81–89
87
Fig. 2 illustrates the 1H NMR spectrum of complex 3. It clearly
shows the assignment of the different signals.
X ¼ Hið4Þ; Clð5Þ; 12CHi3ð6Þ
ð1Þ
The singlet at 8.68 ppm in Fig. 2 is assigned to the iminic proton
which is shifted to low field in comparison of the free ligand
(8.29 ppm). The doublet attributed to Hc,c’ shifts slightly to low
field, due to the coordination of the iminic nitrogen to silver.
The skeleton of the complexes can be drawn with the help of
the HMBC experiment. The assignment of the majority of the car-
bon atoms and their respective coupling constants (1JCAH), are cal-
culated. Due to the great number of phenyl carbon atoms of the
triphenylphophines, a decrease of the sensitivity of some carbon
atoms of the Schiff base should occur.
The 1H NMR spectra of complexes 4–6 show a singlet in the range
9.07–8.96 ppm, which is shifted to low field (average d = 0.51)
with respect to the signals of the free ligands. It is also observed a
D
doublet of doublets for complexes 4 and 5 that appear at 8.22
(3JHaHb = 7.2,
4JHaHc = 1.6 Hz)
and
8.07 ppm
(3JHaHb = 7.6,
4JHaHc = 0.8 Hz), respectively, assigned to the proton Ha of the pyrid-
inic group. For complex 6 a doublet at 8.05 ppm (3J = 7.6 Hz) is ob-
served [71] (see Section 2).
As it was indicated previously, the low sensitivity shown by the
carbon atoms of the Schiff bases in the complexes (13C{1H} and 2D-
HMBC NMR) is related to the presence of PPh3 (ligand:triphenyl-
phosphine = 1:2). Table 3 shows some of the coupling constants
The HMBC spectrum of complex 3 (Fig. 3) shows a signal at
higher field, at 23.0 ppm (1J = 127.5 Hz), attributed to the C12 car-
bon of the methyl group. It also shows a strong interaction be-
n
values (1JCH and JPC, n = 1, 2, 3 or 4) for complexes 4–6. The 13C
0
tween C10,10 and C11 with the methyl proton (Hh), at three and
{1H} NMR spectra of complexes 4–6 show the most characteristic
signals. The spectra show two not resolved signals assigned to
the carbons C6 and C1, which appear in the range 161.7–165.0
and at 123.1–126.6 ppm, respectively. Moreover, the spectra show
two doublets corresponding to the carbon atoms Cmeta and Cortho of
the phenyl groups bonded to the phosphorus atom of the phos-
phine ligands, due to carbon–phosphorus coupling. The signals ap-
pear in the ranges 130.1–130.2 (3JPC = 12.3–19.3 Hz) and 134.4–
134.5 ppm (2JPC = 32.3–39.9 Hz), respectively. They also show a
singlet in the range 131.7–131.8 ppm, assigned to the Cpara carbon
atoms of the triphenylphosphine.
two bonds, respectively. The spectrum shows the coupling of C1
carbon (48.2 ppm) with the methyl protons of the dimethylamino
group (Ha) (1J = 137.3 Hz). The complete assignment of the carbon
atoms and their respective coupling constants are shown in the
Experimental Section.
3.2.2. Synthesis of the silver(I) complexes with bidentate achiral Schiff
bases
The synthesis of the cationic complexes [Ag(j2
-
Ln)(PPh3)2](O3SCF3) [Ln = L4 (4), L5 (5) or L6 (6)] is carried out by
reacting the precursor complex [Ag(O3SCF3)(PPh3)] with the
respective Schiff base in 1:1 molar ratio (Eq. (1)).
e
f
f
H
H
H
e
f
f
H
H
H
g´
d
6
7
4
9
g´
c
10 h´
N
d
3
2
8
5
N
(O3SCF3)
6
7
9
c
4
10 h´
N
11
3
2
g9´
8
[Ag(O3SCF3)(PPh3)]
10
5
N
1
a
b
X
11
g9´
Ag
h
10
h
1
a
b
X
PPh3
Ph3P
3.2.3. Synthesis of the silver(I) complexes with bidentate chiral Schiff
bases
Table 3
1
n
Coupling constants JCH and JPC in Hz (n = 1, 2, 3 or 4) from 13C{1H} and 2D NMR
The complex [Ag(O3SCF3)(PPh3)] reacts with [(S)-(ꢁ)-(6-
(HMBC) spectra for complexes 4–6.
CH3)C5H3N-CHN-CꢀH( -CH3)(C6H5)] (L7-ꢀCS) or S)-(ꢁ)-C5H4N-
a
Compound
Assignment
1JCAH
nJP–C
CHN-CꢀH(
a
-CH3)C6H5 (L8-ꢀCS), in a 1:1 M ratio, to give [Ag(k2-
4
Cmeta
Cpara
Cipso
163.3
159.9
–
3J = 12.3
(S)-(ꢁ)-(6-CH3)C5H3N-CHN-CꢀH(
a-CH3)(C6H5))(PPh3)2](O3SCF3)
4J = Not resolved
1J = 55.4
(7) or [Ag{k2-(S)-(ꢁ)-C5H4N-CHN-CꢀH(
(8) (Scheme 1).
a-CH3)C6H5}(PPh3)](O3SCF3)
Cortho
163.3
2J = 32.5
The 1H NMR spectra show the iminic protons at 8.81 (d,
5
6
C1-He
167.3
161.5
132.2
157.4
160.0
—
–
–
–
4JHP = 0.8 Hz)[67] and 9.45 (s) ppm, respectively for complexes 7
C
C
2-Hd
7-Hf,f
3
or 8. They also show two doublets at 1.42 (7, JHgHf = 6.4 Hz) and
2.04 ppm (8, JHgHf = 6.4 Hz) for the methyl protons (Hg) and a
Cmeta
Cpara
Cipso
3J = 19.1
4J = not resolved
1J = 52.8
2J = 39.9
3
3
quartet for the Hf protons at 4.84 (7, JHfHg = 6.4 Hz) and
5.49 ppm (8, JHfHg = 6.4 Hz) [65]. The 13C{1H} and HMBC
3
Cortho
Not resolved
0
0
NMR[72] show the resonances of C4, C5, C10,10 and C11,11 of the
Schiff base at 137.9 (1J = 164.6 Hz), 121.9 (1J = 170.0 Hz), 128.6
(1J = 164.6 Hz) and 127.0 (1J = 162.4 Hz), respectively. Other reso-
nances are reported in the Section 2.
C7-Hf,f
137.8
124.0
163.4
157.5
—
—
—
C
12-Hi
Cmeta
Cpara
Cipso
3J = 19.3
4J = Not resolved
1J = 59.6
2J = 32.3
The structure of complex 7 has been resolved by X-ray diffrac-
tion studies. Single crystals have been obtained by diffusion of
Cortho
167.3

88
O. Cifuentes et al. / Inorganica Chimica Acta 379 (2011) 81–89
g
e
13
CH3
H
f
H
h'
d
7
8
i'
5
10'
c
N
4
3
9
11'
6
12
(O3SCF3)
10
j
N
2
11
h
b
Ag
i
g
e
13
CH3
f
H
CH3
H
PPh3
Ph3P
h'
d
7
8
(7)
i'
[Ag(O3SCF3)(PPh3)]
5
10'
c
N
4
3
9
10
11'
6
N
12
g
e
j
13
11
i
h
b
2
CH3
f
H
H
Z
h'
d
Z = 1CH3a (L7-*CS); Ha (L8-*CS)
i'
7
8
5
10'
c
N
4
3
9
11'
12
6
10
j
(O3SCF3)
N
11
h
b
2
Ag
i
H
(8)
Ph3P
Scheme 1. Synthesis of complexes 7 and 8.
Fig. 4. The two independent cations of [Ag((S)-(ꢁ)-(6-CH3)C5H3N-CHN-CꢀH(
a-CH3)(C6H5))(PPh3)2](O3SCF3) (7) in the crystal showing the atom numbering scheme.
Displacement parameter ellipsoids represent 50% probability surfaces. H atoms are omitted for clarity.
Table 5
Table 4
Selected bond lengths (Å) and angles (°) for [Ag(
j
2-(S)-(o-CH3)C5H3N-CHN-
Possible hydrogen bonds for complex 7 [Å and °].
CꢀH(CH3)C6H5)(PPh3)2](O3SCF3) (7)#.
D-Hꢂ ꢂ ꢂA
C(85)-H(85)..O(1)
d(D-H)
d(H...A)
d(D...A)
\(DHA)
Molecule A
Molecule B
0.93
0.93
0.93
0.93
0.93
0.93
0.93
2.54
2.51
2.43
2.52
2.51
2.55
2.47
3.425(7)
3.339(8)
3.274(6)
3.426(6)
3.184(5)
3.293(8)
3.182(6)
158.7
149.0
150.7
165.7
129.7
137.3
133.3
C(5)-H(5)ꢂ ꢂ ꢂO(5)
Bond lengths
Ag(1)-N(1)
Ag(1)-P(1)
Ag(1)-N(2)
Ag(2)-P(2)
N(1)-C(1)
N(1)-C(6)
N(2)-C(7)
N(2)-C(8)
C(7)-H(7)ꢂ ꢂ ꢂO(5)
2.334(3)
2.391(3)
2.4333(11)
2.4730(11)
1.332(5)
1.363(6)
1.254(6)
1.484(5)
Ag(2)-N(3)
Ag(2)-P(3)
Ag(2)-N(4)
Ag(2)-P(4)
N(3)-C(86)
N(3)-C(81)
N(4)-C(87)
N(4)-C(88)
2.435(4)
2.5073(12)
2.378(4)
2.4805(11)
1.323(6)
1.352(5)
1.275(6)
1.487(5)
C(44)-H(44)ꢂ ꢂ ꢂO(2)#1
C(153)-H(153)ꢂ ꢂ ꢂF(1)#2
C(25)-H(25)ꢂ ꢂ ꢂO(3)#3
C(53)-H(53)ꢂ ꢂ ꢂF(5)#4
Symmetry transformations used to generate equivalent atoms:
#1 ꢁ x + 1, y ꢁ 1/2, ꢁz + 1; #2x, y ꢁ 1,z #3 ꢁx + 1,y + 1/2, ꢁz + 1 #4 x,y + 1,z.
Bond angles
P(1)-Ag(1)-P(2)
N(1)-Ag(1)-N(2)
P(2)-Ag(1)-N(2)
P(1)-Ag(1)-N(1)
P(1)-Ag(1)-N(2)
P(2)-Ag(1)-N(1)
Ag(1)-N(1)-C(6)
Ag(1)-N(2)-C(7)
Ag(1)-N(2)-C(8)
N(1)-C(6)-C(7)
N(2)-C(7)-C(6)
N(2)-C(8)-C(9)
C(7)-N(2)- C(8)
127.15(4)
71.56(12)
106.93(9)
120.54(8)
112.38(9)
104.33(9)
113.7(3)
116.2(3)
122.6(3)
116.1(4)
122.2(4)
113.3(4)
120.6(4)
P(3)-Ag(2)-P(4)
N(4)-Ag(2)-N(3)
P(3)-Ag(2)-N(3)
P(4)-Ag(2)-N(4)
P(3)-Ag(2)-N(4)
P(4)-Ag(2)-N(3)
Ag(2)-N(3)-C(86)
Ag(2)-N(4)-C(87)
Ag(2)-N(4)-C(88)
N(3)-C(86)-C(87)
N(4)-C(87)-C(86)
N(3)-C(81)-C(83)
C(87)-N(4)-C(88)
123.66(4)
70.63(12)
106.80(9)
114.44(9)
114.37(9)
114.50(8)
113.3(3)
114.8(3)
127.2(3)
118.3(4)
122.5(4)
119.4(5)
117.6(4)
diethyl ether into a concentrated dichloromethane solution of the
microcrystalline materials to give colorless crystals. A perspective
view of the structure of the cation of complex 7 is shown in
Fig. 4. In Table 4 there is a selection of bond lengths and angles.
Complex 7 crystallizes in the space group P2(1). The silver atom
is coordinated to two phosphorous atoms of two triphenylphos-
phine ligands and two nitrogen atoms of the Schiff base, displaying
a distorted tetrahedral geometry. The major distortion is due to the
restricted bite angle of the dinitrogen ligand, which leads to N–Ag–
N angles of 70.63(12) and 71.56(12)° (two molecules). Ag–P and
Ag–N distances lie in the same range and compare well with those
found in similar tetracoordinated silver complexes [AgL(PPh3)2]+
with the bidentate ligands (L) (2-(4-dimethylaminophenyl)imid-
#
Two crystallographic independent molecules were observed in the asymmetric
unit of 3.

O. Cifuentes et al. / Inorganica Chimica Acta 379 (2011) 81–89
89
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3.3. Conclusions
This work presents the synthesis of different silver complexes of
the general formula [Ag(k1-L)(PPh3)n](O3SCF3) (n = 1 or 2) by reac-
tion of [Ag(O3SCF3)(PPh3)] with mono and bidentate Schiff-bases
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Acknowledgments
We thank the Fondo de Desarrollo Científico y Tecnológico
(FONDECYT) (Grant 1030520) and Beca-CONICYT (Grant 2408002),
Chile; the Dirección de Investigación y Postgrado, Chemistry Faculty
and Grant-VRAID from the Pontificia Universidad Católica de Chile;
and the Dirección General de Investigación Científica y Técnica (CTQ
2010-20500-C02-01) for financial support.
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