Synthesis, spectroscopy and structural characterization of silver(I) complexes containing unidentate N-donor azole-type ligands

Article abstract of DOI:10.1016/j.ica.2005.10.016

From the interaction between azole-type ligands L and AgX (X = NO ₃ or ClO₄) or [AgX(PPh₃)_n] (X = Cl, n = 3; X = MeSO₃, n = 2), new ionic mononuclear [Ag(L)₂]X and [Ag(PPh₃)₃L][X] or neutral mono-([Ag(PPh ₃)_nL(X)]) or di-nuclear ([{Ag(PPh₃)(L)(μ-X)} ₂]) complexes have been obtained which have been characterized through elemental analysis, conductivity measurements, IR, ¹H NMR and, in some cases, also by ³¹P{¹H} NMR spectroscopy, and single-crystal X-ray studies. Stoichiometries and molecular structures are dependent on the nature of the azole (steric hindrance and basicity), of the counter ion, and on the number of the P-donor ligands in the starting reactants. Solution data are consistent with partial dissociation of the complexes, occurring through breaking of both Ag-N and Ag-P bonds.

Full text of DOI:10.1016/j.ica.2005.10.016

Inorganica Chimica Acta 359 (2006) 1504–1512
www.elsevier.com/locate/ica
Synthesis, spectroscopy and structural characterization of
silver(I) complexes containing unidentate N-donor azole-type ligands
c
c,
c
Effendy a,b, Fabio Marchetti , Claudio Pettinari *, Riccardo Pettinari ,
c
a
a
Adriano Pizzabiocca , Brian W. Skelton , Allan H. White
a
Chemistry M313, University of Western Australia, Crawley, WA 6009, Australia
Jurusan Kimia, FMIPA Universitas Negeri Malang, Jalan Surabaya 6, Malang 65145, Indonesia
`
Dipartimento di Scienze Chimiche, Universita degli Studi di Camerino, via S. Agostino 1, 62032 Camerino MC, Italy
b
c
Received 21 September 2005; accepted 17 October 2005
Available online 29 November 2005
Abstract
From the interaction between azole-type ligands L and AgX (X = NO3 or ClO4) or [AgX(PPh3)n] (X = Cl, n = 3; X = MeSO3, n = 2),
new ionic mononuclear [Ag(L)2]X and [Ag(PPh3)3L][X] or neutral mono-([Ag(PPh3)nL(X)]) or di-nuclear ([{Ag(PPh3)(L)(l-X)}2]) com-
plexes have been obtained which have been characterized through elemental analysis, conductivity measurements, IR, 1H NMR and, in
some cases, also by 31P{1H} NMR spectroscopy, and single-crystal X-ray studies. Stoichiometries and molecular structures are depen-
dent on the nature of the azole (steric hindrance and basicity), of the counter ion, and on the number of the P-donor ligands in the start-
ing reactants. Solution data are consistent with partial dissociation of the complexes, occurring through breaking of both Ag–N and
Ag–P bonds.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Azole; Silver; Phosphine; X-ray
1. Introduction
ethylimidazole, meim = 1-methylimidazole, imme = 2-
methylimidazole, imph = 4-phenylimidazole, bzim = ben-
zoimidazole, pzH = pyrazole, mpz = 3-methylpyrazole,
dmpz = 3,5-dimethylpyrazole, and tzH = triazole), charac-
terizing a representative array by X-ray diffraction studies
and spectroscopic and analytical measurements.
There has been a growing contemporary interest in the
coordination chemistry of silver(I) derivatives containing
azole ligands, due to potential applications in photography
or silver-plating by electrochemical processes [1–4]. Some
of them also display antimicrobial and anticancer activity
[5–7], and macrocyclic silver(I) compounds undergo very
slow acid-dependent decomplexation and therefore may
be useful for 111Ag-based radioimmunotherapy [8,9].
As a continuation of our previous studies on the struc-
tural and spectroscopic properties of mixed phosphine/N-
donor derivatives of silver(I) [10], we have synthesized
some new silver(I) complexes containing azole-type ligands
(imH = imidazole, imb = 1-benzylimidazole, imet = 2-
2. Experimental
2.1. Materials and methods
Solvents were used as supplied or distilled using stan-
dard methods. All chemicals were purchased from Aldrich
(Milwaukee) and used as received. The samples for micro-
analyses were dried in vacuum to constant weight (20 ꢁC,
ca. 0.1 Torr). Elemental analyses (C, H, N, S) were per-
formed in-house with a Fisons Instruments 1108 CHNS-
O Elemental Analyser. Melting points are uncorrected
*
Corresponding author. Tel.: +39 0737 402234; fax: +39 0737 637345.
E-mail address: claudio.pettinari@unicam.it (C. Pettinari).
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.10.016

Effendy et al. / Inorganica Chimica Acta 359 (2006) 1504–1512
1505
and were measured on an SMP3 Stuart Scientific Instru-
ment, and on a capillary apparatus. IR spectra were
recorded from 4000 to 200 cmꢀ1 using a Perkin–Elmer Sys-
tem 2000 FT-IR instrument. 1H and 31P NMR spectra
were recorded on a VXR-300 Varian spectrometer operat-
ing at room temperature (300 MHz for 1H and 121.4 MHz
for 31P) and on a Mercury Plus Varian 400 NMR spec-
45.28; H, 3.92; N, 10.43%. IR (nujol, cmꢀ1): 3148w,
3123m m(Carom–H), 1519sbr m(C@C + C@N), 1090vs br,
622s m(ClO4). 1H NMR (CDCl3): d, 5.16s (3H,
NCH2C6H5), 6.94s, 7.09s (2H, H4imb + H5imb), 7.24t,
7.35t, 7.79d (5H, NCH2C6H5), 8.21s (1H, H2imb).
2.2.3. Synthesis of [AgCl(imH)(PPh3)2] (3)
1
trometer (400 MHz for H, 162.1 MHz for 31P). Proton
Imidazole (imH) (0.136 g, 2 mmol) was added to a sus-
pension of AgCl(PPh3)3 (0.465 g, 1/2 mmol) in diethyl
ether (30 ml). The suspension was allowed to stir at room
temperature for 24 h, and the precipitate then filtered off,
washed with Et2O (10 ml) and shown to be compound 3
(yield 85%). It was re-crystallized from CHCl3. Compound
3 is soluble in DMSO, acetonitrile, acetone and chlorinated
solvent. M.p. 209–211 ꢁC. KM (acetonitrile, 10ꢀ3 M,
Xꢀ1 cm2 molꢀ1): 5.4. Anal. Calc. for C39H34AgClN2P2: C,
63.65; H, 4.66; N, 3.81. Found: C, 63.88; H, 4.84; N,
chemical shifts are reported in ppm versus Me4Si while
phosphorus chemical shifts are reported in ppm versus
85% H3PO4. Peak multiplicities are abbreviated: singlet,
s; doublet, d; triplet, t; multiplet, m. The electrical conduc-
tances (KM, reported as Xꢀ1 cm2 molꢀ1) of acetonitrile
solutions were measured with a Crison CDTM 522 conduc-
timeter at room temperature.
2.2. Syntheses
4.01%. IR (nujol, cmꢀ1): 3120br m(N–H), 3068w m(Carom
–
Safety note. Perchlorate salts of metal complexes with
organic ligands are potentially explosive! Only small
amounts of materials should be prepared, and these should
be handled with great caution.
H), 1521sbr m(C@C + C@N), 515s, 502s, 493s m(y-mode
of PPh3), 440m, 427m m(t-mode of PPh3). 1H NMR
(CDCl3): d, 6.10br (1H, N–HimH), 7.05s (2H,
H4imH + H5imH), 7.20–7.50m (30H, CHarom), 7.69s (1H,
H2imH). 31P{1H} NMR (CDCl3, 293 K): d, 10.8s. 31P{1H}
The precursor AgCl(PPh3)3 was synthesized by the pro-
cedures previously reported [11]. The precursor
Ag(SO3Me)(PPh3)2 Æ H2O was prepared as follows: to an
ethanol solution (30 ml) of PPh3 (0.524 g, 2 mmol),
AgSO3Me (0.203 g, 1 mmol) was added. The clear solution
was refluxed for 2 h, then cooled and left overnight to evap-
orate. Upon addition of diethyl ether (10 ml), a colorless
precipitate deposited, which was filtered off, washed with
diethyl ether (5 ml) and dried to constant weight. Yield:
75%. Anal. Calc. for C37H35AgO4P2S: C, 59.61; H, 4.73;
S, 4.30. Found: C, 59.95; H, 4.94; S, 4.08%. IR (nujol,
cmꢀ1): 3340br m(O–Hꢁ ꢁ ꢁO), 1666m d(O–Hꢁ ꢁ ꢁO), 1172s,
1164s m(SO3Me), 516s, 502s, 492s m(y-mode of PPh3),
446m, 435m m(t-mode of PPh3). 1H NMR (CDCl3): d,
1.8s br (2H, H2O), 2.54s (3H, SO3CH3), 7.25–7.55m
(30H, CHarom). 31P{1H} NMR (CDCl3, 293 K): d, 10.5s.
1
NMR (CDCl3, 218 K): d, 12.5 (d br, J(Ag–31P): 721 Hz),
1
7.4 (d br, J(Ag–31P): 448 Hz).
2.2.4. Synthesis of [AgCl(imet)(PPh3)2] (4)
2-Ethylimidazole (imet) (0.192 g, 2 mmol) was added to
a suspension of AgCl(PPh3)3 (0.465 g, 1/2 mmol) in diethyl
ether (30 ml). The suspension was allowed to stir at room
temperature for 24 h, and the precipitate then filtered off,
washed with Et2O (10 ml) and shown to be compound 4
(yield 88%) which was re-crystallised from CHCl3. Com-
pound 4 is soluble in DMSO, acetonitrile, acetone and chlo-
rinated solvent. M.p. 181–184 ꢁC. KM (acetonitrile, 10ꢀ3 M,
Xꢀ1 cm2 molꢀ1): 7.1. Anal. Calc. for C41H38AgClN2P2: C,
64.45; H, 5.01; N, 3.67. Found: C, 64.67; H, 5.13; N,
3.39%. IR (nujol, cmꢀ1): 3123br m(N–H), 3074w m(Carom
–
1
31P{1H} NMR (CDCl3, 218 K): d, 9.8 (dd, J(109Ag–31P):
H), 1520sbr m(C@C + C@N), 511s, 500s, 494s m(y-mode of
1
1
539 Hz, J(107Ag–31P): 467 Hz).
PPh3), 437m, 426m m(t-mode of PPh3). H NMR (CDCl3):
d, 1.26t, 2.75q (5H, CH2imet + CH3imet), 5.50br (1H,
NHimet), 6.88s (2H, H4imet + H5imet), 7.18–7.45m (30H,
CHarom). 31P{1H} NMR (CDCl3, 293 K): d, 6.1s. 31P{1H}
2.2.1. Synthesis of [Ag(imH)2](NO3) (1)
Derivative 1 has been prepared by a procedure similar to
that previously reported [12,13]. It was re-crystallized from
hot chloroform. Analytical and spectral data are consistent
with those reported in the literature [12,13].
1
NMR (CDCl3, 218 K): d, 7.2 (d br, J(Ag–31P): 431 Hz),
1
3.1 (d br, J(Ag–31P): 310 Hz).
2.2.5. Synthesis of [AgCl(imme)(PPh3)2] (5)
2.2.2. Synthesis of [Ag(imb)2](ClO4) (2)
Derivative 5 was prepared similarly as that for 4 but
using 2-methylimidazole (imme). Compound 5 is soluble
in DMSO, acetonitrile, acetone and chlorinated solvent.
Yield: 74%. M.p. 202–203 ꢁC. KM (acetonitrile, 10ꢀ3 M,
Xꢀ1 cm2 molꢀ1): 5.4. Anal. Calc. for C40H36AgClN2P2: C,
64.06; H, 4.84; N, 3.74. Found: C, 63.55; H, 4.98; N,
1-Benzylimidazole (imb) (0.312 g, 2 mmol) was added to
a solution of AgClO4 (0.207 g, 1 mmol) in ethanol (20 ml).
A colorless precipitate immediately formed, which was fil-
tered off, washed with Et2O (10 ml) and shown to be com-
pound
2 (yield 76%). It was re-crystallized from
acetonitrile. Compound 2 is soluble in DMSO, acetonitrile,
acetone and chlorinated solvent. M.p. 180 ꢁC dec. KM (ace-
tonitrile, 10ꢀ3 M, Xꢀ1 cm2 molꢀ1): 134.8. Anal. Calc. for
C20H20AgClN4O4: C, 45.87; H, 3.85; N, 10.70. Found: C,
3.65%. IR (nujol, cmꢀ1): 3120br m(N–H), 3065w m(Carom
–
H), 1583m, 1556m m(C@C + C@N), 511s, 504s, 494s m(y-
1
mode of PPh3), 437m, 426m m(t-mode of PPh3). H NMR
(CDCl3): d, 2.34s (3H, CH3imme), 3.70br (1H, N–Himme),

1506
Effendy et al. / Inorganica Chimica Acta 359 (2006) 1504–1512
6.93s (2H, H4imme and H5imme), 7.25–7.45m (30H, CHarom).
31P{1H} NMR (CDCl3, 293 K): d, 10.3s. 31P{1H} NMR
tered off, washed with Et2O (10 ml) and shown to be com-
pound 9 which is soluble in DMSO, acetonitrile, acetone
and chlorinated solvent. Yield: 88%. M.p. 168–170 ꢁC.
KM (acetonitrile, 10ꢀ3 M, Xꢀ1 cm2 molꢀ1): 18.4. Anal.
Calc. for C40H37AgN2O3P2S: C, 60.39; H, 4.69; N, 3.52;
S, 4.03. Found: C, 60.85; H, 4.92; N, 3.59; S, 4.24%. IR
(nujol, cmꢀ1): 3180br m(N–H), 3073w m(Carom–H), 1586m
m(C@C + C@N), 1166s, 1161s, 1154s m(SO3CH3), 534m,
519s, 508s, 486s m(y-mode of PPh3), 434m, 428m, 417m
m(t-mode of PPh3). 1H NMR (CDCl3): d, 2.55s (3H,
SO3CH3), 6.29br (1H, H4pzH), 7.25–7.45m (30H, CHarom
of PPh3) 7.55br (2H, H3pzH + H5pzH). 31P{1H} NMR
(CDCl3, 293 K): d, 8.7s. 31P{1H} NMR (CDCl3, 218 K):
1
(CDCl3, 218 K): d, 11.5 (d br, J(Ag–31P): 625 Hz), 7.3 (d
1
br, J(Ag–31P): 422 Hz).
2.2.6. Synthesis of [Ag(imph)(PPh3)3]Cl (6)
Derivative 6 was prepared similarly as that for 4 but
using 4-phenylimidazole (impH). Compound 6 is soluble
in DMSO, acetonitrile, acetone and chlorinated solvent.
Yield: 94%. M.p. 174–176 ꢁC. KM (acetonitrile, 10ꢀ3 M,
Xꢀ1 cm2 molꢀ1): 151.6. Anal. Calc. for C63H53AgClN2P3:
C, 70.43; H, 4.97; N, 2.61. Found: C, 69.88; H, 5.16; N,
2.90%. IR (nujol, cmꢀ1): 3115m m(N–H), 3071w m(Carom
–
1
1
H), 1583br m(C@C + C@N), 513s, 499s, 494s m(y-mode of
d, 7.9 (dd, J(109Ag–31P): 475 Hz, J(107Ag–31P): 417 Hz).
1
PPh3), 440m, 417w m(t-mode of PPh3). H NMR (CDCl3):
d, 4.70br (1H, NHimph), 7.15s (2H, H4imH + H5imH), 7.20–
7.45m, 7.62t, 7.70d (50H, CHarom + CHimH). 31P{1H}
NMR (CDCl3, 293 K): d, 6.6s. 31P{1H} NMR (CDCl3,
2.2.10. Synthesis of [Ag(MeSO3)(mpz)(PPh3)2] (10)
Derivative 10 was prepared similarly as that for 9in 78%
yield. It was re-crystallized from CHCl3. Compound 10 is
soluble in DMSO, acetonitrile, acetone and chlorinated
solvent. M.p. 168–171 ꢁC. KM (acetonitrile, 10ꢀ3 M,
Xꢀ1 cm2 molꢀ1): 16.6. Anal. Calc. for C41H39AgN2O3P2S:
C, 60.82; H, 4.86; N, 3.46; S, 3.96. Found: C, 60.32; H,
4.98; N, 3.46; S, 3.89%. IR (nujol, cmꢀ1): 3300br m(N–H),
3103w, 3078w m(Carom–H), 1582m m(C@C + C@N),
1166s, 1157s m(SO3CH3), 528s, 512s, 507s, 492s m(y-mode
of PPh3), 441m, 426m m(t-mode of PPh3). 1H NMR
(CDCl3): d, 2.20s (3H, CH3mpz), 2.54s (3H, SO3CH3),
6.05br (2H, H4mpz + H5mpz), 7.25–7.45m (30H, CHarom).
31P{1H} NMR (CDCl3, 293 K): d, 8.4s. 31P{1H} NMR
1
218 K): d, 6.4 (d br, J(Ag–31P): 345 Hz).
2.2.7. Synthesis of [AgCl(meim)(PPh3)] (7)
Derivative 7 was prepared by the same procedure as that
reported for 4 but using 1-methylimidazole (meim). Com-
pound 7 is soluble in DMSO, acetonitrile, acetone and
chlorinated solvent. Yield: 63%. M.p. 163–167 ꢁC. KM
(acetonitrile, 10ꢀ3 M, Xꢀ1 cm2 molꢀ1): 4.8. Anal. Calc. for
C22H21AgClN2P: C, 54.18; H, 4.34; N, 5.74. Found: C,
53.98; H, 4.50; N, 5.62%. IR (nujol, cmꢀ1): 3065w
m(Carom–H), 1546m, 1526m m(C@C + C@N), 513s, 499s
m(y-mode of PPh3), 431m m(t-mode of PPh3). 1H NMR
(CDCl3): d, 2.21s (3H, N–CH3meim), 6.89s, 7.03s (2H,
H4meim + H5meim), 7.25–7.50m (15H, CHarom). 31P{1H}
NMR (CDCl3, 293 K): d, 10.0s. 31P{1H} NMR (CDCl3,
218 K): d, 12.0 (d br, 1J(Ag–31P): 650 Hz), 7.4 (d br,
1J(Ag–31P): 444 Hz).
1
(CDCl3, 218 K): d, 13.9 (d br, J(Ag–31P): 597 Hz), 7.8 (d
1
br, J(Ag–31P): 445 Hz).
2.2.11. Synthesis of [Ag(MeSO3)(dmpz)(PPh3)2] (11)
Derivative 11 was prepared similarly as that for 9 in 73%
yield. Compound 9 is soluble in DMSO, acetonitrile, ace-
tone and chlorinated solvent. M.p. 167–170 ꢁC. KM (aceto-
nitrile, 10ꢀ3 M, Xꢀ1 cm2 molꢀ1): 21.0. Anal. Calc. for
C42H41AgN2O3P2S: C, 61.25; H, 5.02; N, 3.40; S, 3.89.
Found: C, 60.86; H, 5.15; N, 3.42; S, 4.13%. IR (nujol,
cmꢀ1): 3350br m(N–H), 3106w, 3066w m(Carom–H), 1583m
m(C@C + C@N), 1172s, 1164s m(SO3CH3), 515sbr, 504s,
493s m(y-mode of PPh3), 439m, 421w m(t-mode of PPh3).
1H NMR (CDCl3): d, 2.15s (6H, CH3dmpz), 2.54s (3H,
SO3CH3), 5.00br (1H, NHdmpz), 5.82br (1H, H4dmpz),
7.25–7.40m (30H, CHarom). 31P{1H} NMR (CDCl3,
293 K): d, 7.8s. 31P{1H} NMR (CDCl3, 218 K): d, 7.1
2.2.8. Synthesis of [Ag(bzim)3(PPh3)]Cl (8)
Derivative 8 was prepared similarly as that for 4 but
using benzimidazole. Compound 8 is soluble in DMSO,
acetonitrile, acetone and chlorinated solvent. Yield: 45%.
M.p. 179–183 ꢁC. KM (acetonitrile, 10ꢀ3 M, Xꢀ1cm2
molꢀ1): 148.0. Anal. Calc. for C39H33AgClN6P: C, 61.63;
H, 4.38; N, 11.06. Found: C, 61.32; H, 4.51; N, 10.68%.
IR (nujol, cmꢀ1): 3110m m(N–H), 3064w m(Carom–H),
1585m m(C@C + C@N), 519s, 506s, 492s m(y-mode of
1
PPh3), 443m, 424m m(t-mode of PPh3). H NMR (CDCl3):
1
1
d, 4.50br (3H, NHbzim), 7.15–7.45m, 7.60m (27H, CHarom
+ CHbzim), 8.15s (3H, H2bzim). 31P{1H} NMR (CDCl3,
293 K): d, 12.0s. 31P{1H} NMR (CDCl3, 218 K): d, 12.8
(dd, 1J(109Ag–31P): 658 Hz, 1J(107Ag–31P): 573 Hz), 7.1
(dd, J(109Ag–31P): 495Hz, J(107Ag–31P): 432 Hz), 5.6 (d
br, J(Ag–31P): 235 Hz).
1
2.2.12. Synthesis of [Ag(MeSO3)(tzH)(PPh3)2] (12)
Derivative 12 was prepared similarly as that for 9 in 64%
yield. Compound 12 is soluble in DMSO, acetonitrile, ace-
tone and chlorinated solvent. M.p. 175–177 ꢁC. KM (aceto-
nitrile, 10ꢀ3 M, Xꢀ1 cm2 molꢀ1): 24.3. Anal. Calc. for
C39H36AgN3O3P2S: C, 58.80; H, 4.56; N, 5.27; S, 4.02.
Found: C, 58.47; H, 4.71; N, 5.02; S, 4.03%. IR (nujol,
cmꢀ1): 3200br m(N–H), 1575w m(C@C + C@N), 1170s,
1
(dbr, J(Ag–31P): 402 Hz).
2.2.9. Synthesis of [Ag(MeSO3)(pzH)(PPh3)2] (9)
Pyrazole (pzH) (0.068 g, 1 mmol) was added to a sus-
pension of AgSO3Me(PPh3)3 Æ H2O (0.746 g, 1 mmol) in
diethyl ether (30 ml). The suspension was allowed to stir
at room temperature for 24 h, and the precipitate then fil-

Effendy et al. / Inorganica Chimica Acta 359 (2006) 1504–1512
1507
1165s m(SO3CH3), 536m, 516s, 505s, 492s, 483s m(y-mode of
PPh3), 436m, 424m m(t-mode of PPh3). H NMR (CDCl3):
Variata. The perchlorate chlorine lies close to a crystal-
1
˚
lographic 2-axis (Clꢁ ꢁ ꢁCl 0.509(3) A), about which the
d, 2.58s (3H, SO3CH3), 7.25–7.45m (30H, CHarom), 8.04br
(1H, H3tzH + H5tzH). 31P{1H} NMR (CDCl3, 293 K): d,
10.0s. 31P{1H} NMR (CDCl3, 218 K): d, 9.8 (d br,
anion was modeled as disordered.
2.4.3. [AgCl(imH)(PPh3)2] (3) ” C39H24AgClN2P2,
M = 736.0
1
1J(Ag–31P): 463 Hz), 7.9 (d br, J(Ag–31P): 317 Hz).
Monoclinic, space group P21/c ðC52h; No. 14Þ,
˚
˚
˚
2.3. Structure determinations
a = 13.467(2) A, b = 12.216(2) A, c = 23.555(2) A, b =
115.99(1)ꢁ, V = 3483 A . Dcalc = 1.403 g cmꢀ3
.
lMo
=
=
3
˚
7.8 cmꢀ1; specimen: 0.20 · 0.21 · 0.19 mm; ꢀTꢁmin,max
For 3 and 4, unique room-temperature single-counter
data sets were measured (T ca. 295 K; 2h/h scan mode,
2hmax = 50ꢁ), Gaussian absorption corrections being
applied; for 1, 2, and 10 full spheres of CCD area-detector
diffractometer data sets were measured (Bruker AXS
instrument, monochromatic Mo Ka radiation (k =
0.66, 0.83. 2hmax = 50ꢁ; N = 6115, No = 3852; R = 0.037;
Rw = 0.036 (nw = 9). |Dqmax| = 0.41(3) e Aꢀ3. (x,y,z,Uiso H
)
˚
refined.
2.4.4. [AgCl(imet)(PPh3)2] (4) ” C41H38AgClN2P2,
M = 764.1
˚
0.71073 A), x-scans; T ca. 300 K for 10, 153 K for 1 and
2), yielding Nt(otal) reflections, these merging to N unique
after ꢀempiricalꢁ/multiscan absorption correction (proprie-
tary software; Rint cited), No with F > 4r(F) [I > 3r(I)] for
the single-counter determinations) being considered
ꢀobservedꢁ and used in the full-matrix least-squares refine-
ments, refining anisotropic displacement parameter forms
˚
Monoclinic, space group P21/c, a = 14.220(3) A,
˚
˚
b = 12.285(7) A, c = 23.875(5) A, b = 118.71(2)ꢁ, V =
3658 A . Dcalc (Z = 4) = 1.387 g cmꢀ3. lMo = 7.4 cmꢀ1
;
3
˚
specimen: 0.16 · 0.17 · 0.29 mm; ꢀTꢁmin,max = 0.79, 0.90.
2hmax = 50ꢁ; N = 5729, No = 2988; R = 0.061; Rw = 0.062
ꢀ3
˚
(nw = 4). |Dqmax| = 1.20(2) e A
.
for the non-hydrogen atoms, (x,y,z,Uiso H
strained at estimated values unless otherwise stated. Con-
ventional residuals R, Rw (weights: (r2(F) + 0.000nwF2)ꢀ1
)
being con-
Comment. Displacement parameters at the periphery of
the pendant substituent ethyl group were elevated, but no
disorder was resolvable.
)
are cited at convergence. Neutral atom complex scattering
factors were employed within various versions of the Xtal
program system [14]. Pertinent results are given below
and in the tables and figures, the latter showing 20%
(room-temperature) or 50% (153 K) probability amplitude
displacement envelopes, hydrogen atoms having arbitrary
2.4.5. [Ag(MeSO2O)(mpz)(PPh3)2] (10) ” C41H39Ag-
NO3P2S, M = 809.7
˚
Monoclinic, space group P21/c, a = 13.364(1) A,
˚
˚
b = 14.961(1) A, c = 19.986(2) A, b = 100.218(1)ꢁ, V =
3933 A . Dcalc (Z = 4) = 1.367 g cmꢀ3. lMo = 6.9 cmꢀ1
;
3
˚
˚
radii of 0.1 A. Individual variations in procedure (etc.)
are noted as ꢀvariataꢁ.
specimen: 0.72 · 0.35 · 0.14 mm; ꢀTꢁmin/max = 0.78. 2hmax
=
58ꢁ; Nt = 45684, N = 9926 (Rint = 0.024), No = 6422;
ꢀ3
˚
R = 0.036; Rw = 0.039 (nw = 4). |Dqmax| = 0.80(2) e A
.
2.4. Crystal/refinement data
3. Results and discussion
2.4.1. [Ag(imH)2](NO3) (1) ” C6H8AgN5O3, M = 306.0
Orthorhombic, space group P212121 ðD42; No. 19Þ,
˚
˚
˚
3.1. Syntheses
a = 10.929(1) A, b = 17.535(2) A, c = 5.0062(5) A, V =
3
959.4 A . Dcalc (Z = 4) = 2.118 g cmꢀ3. lMo = 21 cmꢀ1
;
˚
From the reaction of an equivalent of AgX (X = NO3 or
ClO4) with two equivalents of imH or imb in ethanol,
derivatives 1 and 2 (Fig. 1) have been obtained, respec-
tively. The analytical and spectroscopic data confirm the
stoichiometry proposed and conductance measurements
specimen:
0.15 · 0.12 · 0.08 mm;
ꢀTꢁmin/max = 0.77.
2hmax = 75ꢁ; Nt = 19101, N = 2847 (Rint = 0.024), No =
2690; R = 0.021; Rw = 0.026 (nw = 4); xabs = ꢀ0.01(3).
|Dqmax| = 1.14(6) e Aꢀ3. (x,y,z,Uiso H
)
refined. Comment.
˚
This compound has been the subject of early room-temper-
ature studies [11,12], the setting of the former being
employed (as its inverse).
+
2.4.2. [Ag(imb)2](ClO4) (2) ” C20H20AgClN4O4,
M = 523.8
R
N
Monoclinic, space group C2 ðC32; No. 5Þ, a =
N
Ag
N
˚
˚
˚
23.807(3) A, b = 7.8495(9) A, c = 5.6352(6) A, b =
N
98.545(2)ꢁ, V = 1041 A . Dcalc (Z = 2) = 1.670 g cmꢀ3
.
3
˚
X-
R
l
Mo = 11.3 cmꢀ1
ꢀTꢁmin/max = 0.70. 2hmax = 55ꢁ; Nt = 4977, N = 1210 (Rint
0.020), No = 1210; R = 0.017; Rw = 0.022 (nw = 9);
;
specimen: 0.40 · 0.25 · 0.04 mm;
1: X = NO3, R = H
2: X = ClO4, R = Bn
=
ꢀ3
˚
Fig. 1. Molecular structures of derivatives 1 and 2.
xabs = 0.01(2). |Dqmax| = 0.44(2) e A
.

1508
Effendy et al. / Inorganica Chimica Acta 359 (2006) 1504–1512
OSO2Me
carried out in acetonitrile indicate 1:1 ionic compounds
[15].
R˚
The interaction of AgCl(PPh3)3 [11] with excesses of sev-
eral azoles L (L = imH, imet, imme, imph, meim, bzim)
with different electronic and steric features, in diethyl ether,
has yielded derivatives 3–8 (Fig. 2). They show different
stoichiometries, ranging from neutral types [AgCl(L)-
(PPh3)2] (compounds 3–5) and [AgCl(L)(PPh3)] (7) to the
species Ag(L)(PPh3)3Cl (6) and Ag(L)3(PPh3)Cl (8), which
probably are ionic both in the solid and in the solution
state, the conductance measurements for the latter deriva-
tives clearly indicating the existence in acetonitrile solution
of 1:1 electrolytes [15]. The differences in the number of
phosphines replaced in the silver environment by azole
ligands appear to be mainly consequent on the steric hin-
drance of the azole substituents.
X
Ag
N
PPh3
PPh3
N
*R
H
9: R*, R˚ = H, X = CH
10: R* = Me, R˚ = H, X = CH
11: R*, R˚ = Me, X = CH
12: R*, R˚ = H, X = N
Fig. 3. Molecular structures of derivatives 9–12.
also the y-mode and t-mode of PPh3 below 600 cmꢀ1
[16]. In the IR spectra of derivatives 9–12, containing the
SO3Me group, absorptions in the 1100–1200 cmꢀ1 region
confirm the presence of co-ordinated methanesulfonate
groups [17].
Finally, the interaction between equivalents of
Ag(SO3Me)(PPh3)2 Æ H2O and various pyrazoles (pzH,
mpz, dmpz) or triazole (tzH) in diethyl ether afforded the
compounds 9–12, all characterized with the same stoichi-
ometry [Ag(L)(PPh3)2(MeSO2O)] (Fig. 3).
1
The H spectra of derivatives 1–12 have been recorded
in deuterochloroform, the resonances and relative integra-
tions further confirming the stoichiometries proposed for
1–12. The signals of the azole donors are displaced to lower
fields, an evidence of the existence of complexation in solu-
tion, reflecting the changes in the electron density and in p-
electron circulation about the heterocyclic ring. In fact, a
r-charge donation from the N-donor ligand to the metal
centre removes electron density from the ligand, producing
3.2. Spectroscopic characterization
The IR spectra of 1–12 show the expected medium to
weak absorption bands in the range 1550–1600 cmꢀ1 due
to the breathing of the azole rings, the bands up to
3100 cmꢀ1 for the N–H generally broad, indicative of the
presence of extensive H-bonding networks and, for 3–12,
Cl
PPh3
Cl-
Ag
Ag
N
PPh3
N
PPh3
N
PPh3
H
N
PPh3
H
R
6
3: R = H
4: R =Et
5: R = Me
PPh3
Ag
Cl
N
N
HN
N
NH
Ag
N
PPh3
Cl-
N
HN
Me
7
8
Fig. 2. Molecular structures of derivatives 3–8.

Effendy et al. / Inorganica Chimica Acta 359 (2006) 1504–1512
1509
a deshielding which should attenuate at positions remote
3.3. X-ray structural investigation
from the ligand.
Except for derivatives 2 and 7, containing 1-substituted
imidazoles, and derivative 12 containing triazole, all others
exhibit only one broad resonance instead of the two
expected for the protons in the 4 and 5 positions of the
imidazole ligands and in the 3 and 5 positions of the pyraz-
oles, in consequence of the fluxional behavior of these com-
pounds in solution, requiring a concomitant prototropy
and metallotropy of the ligand [18–20].
The results of the single-crystal X-ray studies of com-
plexes 1–4 and 10 are consistent in terms of stoichiometry
and connectivity with the expected formulations. In all
except 2, one formula unit, devoid of solvent, comprises
the asymmetric unit of the structures; in 2, both complex
cation and anion lie on, or close to, crystallographic 2-axes,
one-half of each comprising the asymmetric unit of the
structure. Compounds 3 and 4 are neutral molecules; in
1, 2, and 10, the associations of the anions with the metal
are more tenuous, and the nature of the compounds more
ꢀionicꢁ.
The solution 31P NMR spectra of derivatives 3–12 at
room temperature consist of a broad or narrow singlet,
presumably because of the presence of rapid exchange
equilibria. On cooling the samples at ꢀ55 ꢁC, the single res-
onances split into one or two double doublets, from which
it is possible to determine the 1J(109Ag–31P) and
1J(107Ag–31P) coupling constants. They are mainly deter-
mined by the broad orbital overlap between Ag and P on
the basis of the Fermi contact term [21] and can be related
to the number of coordinated phosphines and covalent ver-
sus ionic character of Ag–P bonds [22]. Derivatives
[AgCl(imH)(PPh3)2] (3) and [AgCl(imme)(PPh3)2] (5)
undergo partial phosphine dissociation in solution, since
two resonances have been detected at low temperature,
one at lower fields having 1J(Ag–P) values higher than
600 Hz (typical of compounds containing only one phos-
phine bonded to silver), whereas the second one at higher
The structure of AgNO3:imH (1:2) has been the subject
of earlier room-temperature studies [12,13], the essential
features of which are confirmed in the present more precise
˚
low-temperature study. Ag–N are 2.115(2), 2.120(2) A,
1
fields with J(Ag–P) values in the range 300–500 Hz indi-
cates the presence of two phosphines bonded to silver.
Also, in the 31P NMR spectra of derivatives [AgCl
(meim)(PPh3)] (7) and [Ag(bzim)3(PPh3)]Cl (8), two differ-
ent resonances have been detected, explicable in terms of
partial dissociation of the azole donor(s) and formation
of an sp-hybridized ClAgP species. Finally, derivatives
9–12, containing coordinated SO3CH3 groups show one
1
or two resonances with J(Ag–P) values in the range 300–
500 Hz, in accordance with two PPh3 ligands bonded to sil-
ver, except for the derivative [Ag(MeSO3)(dmpz)(PPh3)2]
1
(11) which shows a resonance with a J(Ag–P) value of
235 Hz, typical of species containing three or four PPh3
bonded to silver, as a consequence of phosphine redistribu-
tion between a pair of metal centres in solution.
Fig. 4. Unit cell contents of 1, projected down c.
Fig. 5. Unit cell contents of 2, projected down b.

1510
Effendy et al. / Inorganica Chimica Acta 359 (2006) 1504–1512
˚
with N–Ag–N 172.78(8)ꢁ reflecting the rather distant
2.131(2) A and N–Ag–N 170.7(1)ꢁ, perchlorate (disor-
˚
nitrate approach as a chelate Ag–O 2.945(2), 3.129(2) A
dered) oxygens O(1,3) approaching from either side (see
˚
˚
(Fig. 4), the latter impacting somewhat on the associated
Fig. 5) at distances 2.946(5), 2.873(8) A. Ag lies 0.101(6) A
out of the C3N2 plane. Comparative geometries are listed
for the parent imH, imH bonded to Ag and, as well, substi-
tuted at the 3-position by CH2Ph in Table 1. Ag–N dis-
tances in both are generally comparable with those
obtained in a broad array of NAgN pyridine (=ꢀpyꢁ) aro-
matic heterocycle base donor complexes [23]; also of
interest is the comparison with the geometry of [(Ph3P)2-
Ag(2-meim)2]+ (in the nitrate) [10g], where, in a four-
coordinate environment, Ag–N are 2.348(2) (x2); Ag–P
˚
N–O distances 1.256(3), 1.257(3) A which are slightly
˚
longer than the other non-interacting O–N 1.241(3) A;
the angle opposite the latter is 118.6(2)ꢁ with the other pair
120.7(2)ꢁ, 120.6(2)ꢁ. The imidazole hydrogen has no close
˚
contacts. Ag lies 1.745(3) A out of the NO3 plane and
˚
0.130(4) A from the C3N2 plane. In 2, the imidazole hydro-
gen is replaced by a benzyl group, the cation lying with the
silver disposed on a crystallographic 2-axis, with Ag–N
Table 1
˚
2.4704(6) (x2) A.
Comparative imidazole geometries
An AgClNP2 environment has previously been
described via X-ray studies for the py/PPh3 system in
[AgCl(py)(PPh3)2] [24,25]; the geometry for that is com-
pared for those in 3 and 4 (Fig. 6) in Table 2. The values
within all three systems are quite similar insofar as dis-
tances, and Cl–Ag–N and P–Ag–P angles are concerned,
N–Ag–P angles being more diverse, variable and widely
ranged; the Ag–P and P–Ag–P descriptors are similar to
those found in many other [(Ph3P)2Ag(N-unidentate)2] sys-
tems. The present systems are of interest in defining the first
such arrays for imidazole bases, 10 likewise for a pyrazole
base (Fig. 7). The latter is particularly of interest in defining
a [(Ph3P)2(unidentate N-donor)Ag] array in association
with an oxyanion, the interaction of the latter here being
invasive, as tested by the NAgP2 angle sum which is dimin-
ished well below 360ꢁ (being 352.8ꢁ) (Table 2); the impact
on the S–O (bonded) distance, however, appears negligible
System
imHa
(Ag) imH (1; imH 1, 2) (Ag)(imb) (2)b
˚
Distances (A)
N(1)–C(2)
C(2)–N(3)
N(3)–C(4)
C(4)–C(5)
N(1)–C(5)
1.358(1) 1.326(3), 1.328(3)
1.333(1) 1.344(3), 1.344(4)
1.389(1) 1.372(3), 1.364(4)
1.378(1) 1.366(4), 1.367(4)
1.381(1) 1.383(5), 1.379(3)
1.330(5)
1.345(4)
1.381(5)
1.363(4)
1.377(4)
Angles (ꢁ)
Ag–N(1)–C(2)
Ag–N(1)–C(5)
C(2)–N(1)–C(5) 107.2(1)
N(1)–C(2)–N(3) 111.8(1)
C(2)–N(3)–C(4) 105.3(1)
N(3)–C(4)–C(5) 109.8(1)
C(4)–C(5)–N(1) 106.0(1)
a
126.7(2), 121.9(2)
126.8(2), 131.8(2)
124.6(2)
128.4(2)
106.9(2)
110.3(3)
107.5(3)
106.5(3)
108.7(3)
106.0(2), 106.1(5)
110.9(2), 110.5(2)
107.9(2), 108.3(2)
106.1(2), 106.1(2)
109.1(2), 109.1(2)
Derivative of neutron data (103 K), values corrected for libration [26].
N(3)–C(30) is 1.470(4) A; C(30)–N(3)–C2,5) are 125.5(3)ꢁ and
b
˚
126.7(2)ꢁ.
Fig. 6. Molecular projections of: (a) [AgCl(imH)(PPh3)2] (3) and (b) [AgCl(imet)(PPh3)2] (4), down the Cl–Ag bonds.

Effendy et al. / Inorganica Chimica Acta 359 (2006) 1504–1512
1511
Table 2
Comparative XAgNP2 environments, 3, 4 and 10 ([(PPh3)2Ag(N-base)X] systems)
System
[ClAg(py)(PPh3)2]a
3 (X = Cl)
4 (X = Cl)
10 (X = O, SO2, Me)b
˚
Distances (A)
X–Ag
Ag–N
2.517(2)
2.503(4)
2.477(2)
2.474(2)
2.586(1)
2.381(4)
2.454(1)
2.466(2)
2.609(3)
2.359(8)
2.454(4)
2.464(4)
2.505(3)
2.312(2)
2.4393(7)
2.4663(7)
Ag–P
Angles (ꢁ)
X–Ag–N
X–Ag–P
94.6(1)
115.49(2)
113.22(7)
105.4(1)
97.1(1)
96.1(1)
110.60(5)
112.69(5)
106.8(1)
98.4(1)
99.2(2)
103.3(1)
108.7(1)
112.2(3)
102.7(3)
127.3(1)
95.17(9)
90.06(6)
112.44(7)
122.49(7)
103.91(7)
126.40(2)
N–Ag–P
P–Ag–P
123.60(7)
126.46(5)
Ag–P(C(nm1)–C(ortho) torsion angles (ꢁ) (acute)
nm = 11
ꢀ56.5(5)
ꢀ39.7(6)
ꢀ32.5(5)
ꢀ45.2(5)
ꢀ50.0(5)
ꢀ29.3(5)
36.0(5)
49.1(4)
44.5(6)
18.1(5)
31.2(5)
59.2(5)
17(1)
33(1)
54(1)
31(1)
49(1)
35(1)
ꢀ12.7(2)
ꢀ22.8(2)
ꢀ62.5(2)
ꢀ11.8(2)
ꢀ41.0(2)
ꢀ58.8(2)
12
13
21
22
23
a
Refs. [24,25].
b
˚
In the anion (ordered), S–O (coordinated; uncoordinated (·2) x are 1.410(3); 1.434(3), 1.399(4) A.
4. Supplementary material
X-ray crystallographic files, in .cif format, for the struc-
ture determinations of derivatives 1, 2, 3, 4, and 9 have
been deposited with the Cambridge Crystallographic Data
Centre, CCDC Nos. 283883–283887. Copies of this infor-
mation may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax:
+44 1223 336 033; e-mail: deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk).
Acknowledgements
Thanks are due to the University of Camerino (Italy),
Carima Foundation for financial support and INTAS pro-
ject 00-469.
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