Synthesis and spectroscopic characterization (IR, 1H and 31P NMR, electrospray ionization mass) of mono-, di-, tetra- and poly-meric complexes of silver(I) with diphosphine ligands: X-ray crystal structures of AgNO2:(Ph2PCH2 PPh2)(1:1)2, AgNO2:(Ph2P(CH2)3PPh2) (1:1)2, AgNO2: (Ph2PCH=CHPPh2) (2:1)2 and AgNO2:{p-tolyl)2P(C10H6)2P(p-tolyl)2} (1:1)

Article abstract of DOI:10.1016/j.ica.2003.11.010

Adducts of diphosphine ligands R₂P(R^′) _nPR₂ (dppm: R=Ph, R^′=CH₂, n= 1; dppe: R=Ph, R^′=CH₂, n=2; dppp: R=Ph, R ^′= CH₂, n=3; dppb: R=Ph, R^′= CH₂, n=4; dppf: R=Ph, R^′=ferrocenyl, n=1; dppet: R=Ph, R^′=CH=CH, n=1; dcpm: R=cy, R^′=CH ₂, n=1; S-Binap: R=Ph, R^′= (S)-(+)-1,1-binaphthyl, n=1, n=2; (R-Tol-Binap: R=p-tolyl; R^′=(R)-(+)-1,1-binaphthyl, n=1; (S,S-Diop: R=Ph, R^′=(4S,5S-(+)-O-isopropylidene-2-3- dihydroxybutane, n=1) with silver(I) nitrite have been synthesized and characterized both in solution (¹H, ³¹P NMR, ESI MS) and in the solid state (IR, single crystal X-ray structure analysis, ³¹P NMR). The topologies of the structures in the solid state were found to depend on the nature of the diphosphine and in some cases also on the stoichiometric ratio AgNO₂:R₂P(R^′)_nPR ₂. The adducts AgNO₂:dppm (1:1)₂ and AgNO ₂:dppp (1:1)₂ are dimers, the role of dppm and dppp being to bridge two silver centers with each nitrite O,O^′-chelating. The adduct AgNO₂:dppet (2:1)₂ is tetranuclear, derivative of the chair form, the bidentate ligands bridging central and peripheral silver centers, the nitrite being coordinated through both oxygens, the first unidentate, the second bridging bidentate. R-Tol-Binap forms a mononuclear 1:1 adduct, with the nitrite an O,O^′-chelate.

Full text of DOI:10.1016/j.ica.2003.11.010

Inorganica Chimica Acta 357 (2004) 1523–1537
www.elsevier.com/locate/ica
1
31
Synthesis and spectroscopic characterization (IR, H and P NMR,
electrospray ionization mass) of mono-, di-, tetra- and poly-meric
complexes of silver(I) with diphosphine ligands: X-ray crystal
structures of AgNO2:(Ph2PCH2PPh2) (1:1)2, AgNO2:(Ph2P(CH2)3
PPh2) (1:1)2, AgNO2:(Ph2PCH@CHPPh2) (2:1)2 and AgNO2:
{p-tolyl)2P(C10H6)2P(p-tolyl)2} (1:1) q
c
d
d
Effendy a,b, John V. Hanna , Fabio Marchetti , Domenico Martini ,
d,
d
b
b
Claudio Pettinari *, Riccardo Pettinari , Brian W. Skelton , Allan H. White
a
Jurusan Kimia, FMIPA Universitas Negeri Malang, Jalan Surabaya 6, Malang 65145, Indonesia
b
Department of Chemistry, The University of Western Australia, Crawley, WA 6009, Australia
c
ANSTO NMR Facility, Materials Division, Private Mail Bag 1, Menai, NSW 2234, Australia
Dipartimento di Scienze Chimiche, Universitꢀa degli Studi di Camerino, via S. Agostino 1, 62032 Camerino MC, Italy
d
Received 3 November 2003; accepted 8 November 2003
Abstract
Adducts of diphosphine ligands R2P(R0)nPR2 (dppm: R ¼ Ph, R0 ¼ CH2, n ¼ 1; dppe: R ¼ Ph, R0 ¼ CH2, n ¼ 2; dppp: R ¼ Ph,
R0 ¼ CH2, n ¼ 3; dppb: R ¼ Ph, R0 ¼ CH2, n ¼ 4; dppf: R ¼ Ph, R0 ¼ ferrocenyl, n ¼ 1; dppet: R ¼ Ph, R0 ¼ CH@CH, n ¼ 1; dcpm:
R ¼ cy, R0 ¼ CH2, n ¼ 1; S-Binap: R ¼ Ph, R0 ¼ (S)-(+)-1,1-binaphthyl, n ¼ 1, n ¼ 2; (R-Tol-Binap: R ¼ p-tolyl; R0 ¼ (R)-(+)-1,1-
binaphthyl, n ¼ 1; (S,S-Diop: R ¼ Ph, R0 ¼ (4S,5S-(+)-O-isopropylidene-2-3-dihydroxybutane, n ¼ 1) with silver(I) nitrite have been
synthesized and characterized both in solution (1H, 31P NMR, ESI MS) and in the solid state (IR, single crystal X-ray structure
analysis, 31P NMR). The topologies of the structures in the solid state were found to depend on the nature of the diphosphine and in
some cases also on the stoichiometric ratio AgNO2:R2P(R0)nPR2. The adducts AgNO2:dppm (1:1)2 and AgNO2:dppp (1:1)2 are
dimers, the role of dppm and dppp being to bridge two silver centers with each nitrite O,O0-chelating. The adduct AgNO2:dppet
(2:1)2 is tetranuclear, derivative of the chair form, the bidentate ligands bridging central and peripheral silver centers, the nitrite
being coordinated through both oxygens, the first unidentate, the second bridging bidentate. R-Tol-Binap forms a mononuclear 1:1
adduct, with the nitrite an O,O0-chelate.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Silver; 31P NMR CPMAS; X-ray crystal structure; Diphosphine
1. Introduction
affording binuclear metal complexes in the l-dppm form,
while dppe affords both chelating and bridging com-
plexes. dppm Complexes containing the M2(dppm)2
structural unit have been intensively investigated [1–3].
Although a key feature of the chemistry of this class of
complexes is the relatively stable and quasi-planar M2P4
framework where two metal atoms are connected by
a pair of bridging dppm ligands, it is well known that
a variety of structural possibilities can occur when
low-valent metals are bonded to a bidentate phosphine
and a labile ligand such as nitrate or carboxylate [4,5].
The versatile diphosphine ligands are particularly
appropriate for the synthesis of low-valent metal com-
plexes. Bis(diphenylphosphino)methane (dppm) and 1,2-
bis(diphenylphosphino)ethane (dppe) are widely used in
inorganic chemistry, bis(diphenylphosphino)methane
q Supplementary data associated with this article can be found, in the
online version, at doi: 10.1016/j.ica.2003.11.010.
* Corresponding author. Tel.: +39-0737-402234; fax: +39-0737-637345.
E-mail address: claudio.pettinari@unicam.it (C. Pettinari).
0020-1693/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2003.11.010

1524
Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
CH@CH, n ¼ 1; dcpm: R ¼ cy, R0 ¼ CH2, n ¼ 1; S-Binap:
Ph
P
R
P
Ph
R
R
R ¼ Ph, R0 ¼ (R)-(+)-1,1-binaphthyl, n ¼ 1, n ¼ 2; (R-
Tol-Binap: R ¼ p-tolyl; R0 ¼ (R)-(+)-1,1-binaphthyl, n ¼
1; (S,S-Diop: R ¼ Ph, R0 ¼ (4S,5S-(+)-O-isopropylidene-
2-3-dihydroxybutane, n ¼ 1) were purchased from Aldrich
and used without further purification. All reactions were
carried out under an atmosphere of dry oxygen-free dini-
trogen, using standard Schlenk techniques and protected
from light. All solvents were dried, degassed and distilled
prior to use. Elemental analyses (C, H, N) were performed
with a Fisons Instruments 1108 CHNS-O Elemental
analyser. IR spectra were recorded from 4000 to 100 cmꢀ1
tolyl
tolyl
tolyl
tolyl
H
H
n(H2C)
P
P
P
P
R
Ph Ph
dppm: R = Ph, n = 1
dppe: R = Ph, n = 2
dppp: R = Ph, n = 3
dppb: R = Ph, n = 4
dppc: R = cy, n = 1
dppet
R-TolBinap
Ph
P
Ph
Ph
Ph
Ph
H
H
Ph
Ph
Ph
P
CH3
CH3
O
O
P
Ph
P
Fe
P
Ph
Ph
P
Ph
dppf
S,S-DIOP
1
with a Perkin–Elmer System 2000 FT-IR instrument. H
S-Binap
and 31P NMR spectra were recorded on a VXR-300
Varian spectrometer operating at room temperature (300
MHz for 1H, and 121.4 MHz for 31P). 31P CPMAS solid-
state NMR spectra were acquired at room temperature on
a Bruker MSL-400 spectrometer operating at a field
strength of 9.40 T (400.13 MHz for 1H and 161.924 MHz
for 31P). Conventional cross-polarization and magic-
angle-spinning techniques, coupled with spin temperature
alternation to eliminate spectral artefacts, were imple-
mented using a Bruker 4 mm double-air-bearing probe in
which MAS frequencies of ꢁ10 kHz were achieved. A
recycle delay of 30 s, a 1H–31P contact period of 10 ms, a
Fig. 1. Structures of the ligands employed in this work.
The interaction between bidentate diphosphines
R2P(R0)nPR2 and silver salts has recently attracted a
great deal of interest because the resultant complexes
have found applications in homogeneous catalysis [6] and
also as antitumor compounds [7]. For example silver(I)
carboxylate-(S)-Binap (S-Binap ¼ (S)-(-)-2,20-bis(diph-
enylphosphino)-1,10-binaphthyl) complexes have been
recently reported as highly efficient catalysts for the
Mukaiyama aldol reaction using silyl enol ethers or ke-
tene silyl acetals as nucleophiles [8–10], this kind of cat-
alyst strongly activating nucleophiles to undergo the
aldol reaction easily. Catalytic asymmetric allylation of
aldehydes using a chiral silver(I) complex has been also
reported by Yamamoto and coworkers [11].
The interplay of parameters such as the geometrical
flexibility of Ag(I), bite angle, electronic properties of
the phosphine, and coordination mode of the supporting
ligands often renders predictions concerning the struc-
tures and properties of silver-diphosphino complexes [7],
both in solution and in the solid state, difficult [12,13]; to
date little systematic work has been reported on the
interaction between silver salts and diphosphines char-
acterized by different spacers R0 or substituents R. The
purpose of this work is to further clarify the effect of R
and R0 on the coordination mode of phosphine and on
the coordination environment of silver(I); we report
hereunder results obtained concerning the interaction
between AgNO2 and the diphosphines depicted in
Fig. 1, to assist our understanding of the Ag(I) species
present both in solid and solution.
1
1H p=2 pulse length of 3 ls and H decoupling fields of
85–90 kHz (during acquisition) were used in these mea-
surements. No spectral smoothing was invoked prior to
Fourier transformation. The 2D 31P CPCOSY experiment
was implemented with the TPPI (time proportional phase
incrementation) method [14–16] for the acquisition of
phase-sensitive data in both the F1 and F2 dimensions. The
application of this technique has been discussed in detail
1
elsewhere [17]. The recycle delay, contact period, H p=2
pulse length and MAS rate were the same as those im-
plemented in the above 1D 31P CPMAS experiments. A
total of 256 F1 increments were acquired into 256 word
blocks, with both dimensions zero-filled to 1 K words and
weighted with sine-bell multiplication prior to Fourier
transformation. All chemical shifts in these 1D and 2D
experiments were externally referenced to 85% H3PO4 via
solid triphenylphosphine (d, )9.9).
The electrical resistance of CH2Cl2 solutions was
measured with a Crison CDTM 522 conductimeter at
room temperature. The positive and negative electro-
spray mass spectra were obtained with a Series 1100
MSI detector HP spectrometer, using an acetonitrile
mobile phase. Solutions (3 mg/ml) for electrospray
ionization mass spectrometry (ESI-MS) were prepared
using reagent grade acetone or acetonitrile. For the ESI-
MS data, masses and intensities were compared to those
calculated using the IsoPro Isotopic Abundance Simu-
lator, version 2.1) [18]. Peaks containing silver(I) ions
were identified as the center of an isotopic cluster.
Melting points were obtained using a Stuart SMP3
melting point apparatus and were not corrected. Mo-
2. Experimental
2.1. Materials and methods
AgNO2 and R2P(R0)nPR2 (dppm: R ¼ Ph, R0 ¼ CH2,
n ¼ 1; dppe: R ¼ Ph, R0 ¼ CH2, n ¼ 2; dppp: R ¼ Ph,
R0 ¼ CH2, n ¼ 3; dppb: R ¼ Ph, R0 ¼ CH2, n ¼ 4; dppf:
R ¼ Ph, R0 ¼ ferrocenyl, n ¼ 1; dppet: R ¼ Ph, R0 ¼

Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
1525
lecular mass determination of compound 1 (solution)
was performed at 40 °C with a Knauer KNA0280 vapor
pressure osmometer calibrated with benzil. The solvent
was Baker Analyzed Spectrophotometric grade chloro-
form. The results were reproducible to ꢂ2%.
PCH2CH2P), 7.20–7.50m (20H, PC6H5). Kmol (CH2Cl2,
concentration¼ 1.00 ꢃ 10ꢀ3 M): 2.4 Xꢀ1 cm2 molꢀ1. IR
(cmꢀ1): 3070w, 3049w [m(C–H)], 1664w, 1617w [m(NO2)],
1586w, 1572w [m(C@C)], 1435s, 1333w, 1320m
[masym(NO)], 1308m, 1277w, 1214m [msym(NO)], 1185m,
1175s, 1158m 844w, 828m [d(ONO)], 508vs, 482s, 474s,
464m, 418m [m(P–Ph)], 342m, 315w, 303w, 280m, 264w,
254m, 224w, 203w. ESI MS (MeCN): (+) 905 (100)
[Ag(dppe)2]þ. Anal. Calc. for C26H24AgNO2P2: C, 56.54;
H, 4.38; N, 2.54. Found: C, 56.34; H, 4.39; N, 2.38%.
2.2. Syntheses
2.2.1. Synthesis of [(AgNO2)2(dppm)3] (1)
AgNO2 (0.154 g, 1 mmol) was added to a methanol
solution (30 ml) of dppm (0.961 g, 2.5 mmol), at 60 °C.
After the addition, the solution was stirred for 24 h at 60 °C
in the dark. A colorless precipitate formed which was fil-
tered off and washed with methanol (3ꢃ 5 ml). Crystalli-
zation from methanol gave complex 1 as a microcrystalline
solid in 68% yield. M.p. 113 °C. 1H NMR (CDCl3, 293 K):
d 3.3 br (2H, PCH2P), 7.20–7.30m, 7.40–7.50m (20H,
PC6H5). Kmol (CH2Cl2, concentration¼ 1.00 ꢃ 10ꢀ3 M):
7.9 Xꢀ1 cm2 molꢀ1. IR (cmꢀ1): 3048w [m(C–H)], 1572m
[m(C@C)], 1432s, 1332m, 1310m, 1271w [masym(NO)], 1174s
br [msym(NO)], 843m [d(ONO)], 518s, 503s, 472s, 462s,
446m, 438m, 427w [m(P–Ph)], 369m, 352w, 338m, 315w,
303m, 281m, 264w, 252w, 244w, 225m, 208w. ESI MS
(MeCN): (+) 684 (20) [Ag2NO2(dppm)]þ, 876 (70)
[Ag(dppm)2]þ, 892 (25) [Ag(dppm)2 + O]þ, 1030 (100)
[Ag2NO2(dppm)2]þ, 1526 (80) [Ag2NO3(dppmO2)2]þ.
Anal. Calc. for C75H66-Ag2N2O4P6: C, 61.66; H, 4.55; N,
1.92. Found: C, 61.32; H, 4.76; N, 1.97%.
2.2.4. Synthesis of [Ag(dppe)2]NO2 (4)
Compound 4 was prepared as for 3, using 1 mmol of
AgNO2 and 2 mmol of dppe, re-crystallization from
methanol giving a microcrystalline solid in 45% yield.
M.p. 235 °C. 1H NMR (CDCl3, 293 K): d 2.42m br
(4H, PCH2CH2P), 7.12–7.50m, 7.65–7.75m, 7.85–7.95m
(20H, PC6H5). Kmol (CH2Cl2, concentration ¼ 1:00ꢃ
10ꢀ3 M): 44.2 Xꢀ1 cm2 molꢀ1. IR (cmꢀ1): 3043w [m(C–
H)], 1586w, 1569w, [m(C@C)], 1432m, 1303w, 1273w
[masym(NO)], 1175m, 1151m [msym(NO)], 889m, 850m,
814w [d(ONO)], 509vs, 477s, 462m, 440m, 430m, 418m,
400m [m(P–Ph)], 374w, 340m, 302m, 280s, 266w, 253m,
246m, 223m, 213w. ESI MS (MeCN): (+) 905 (100)
[Ag(dppe)2]þ. Anal. Calc. for C52H48AgNO2P4: C, 65.69;
H, 5.09; N, 1.47. Found: C, 65.66; H, 5.02; N, 1.58%.
2.2.5. Synthesis of [AgNO2(dppp)]2 (5)
Compound 5 was prepared as for 3, using 1 mmol of
AgNO2 and 1 mmol of dppp, re-crystallization from
methanol giving a microcrystalline solid in 54% yield.
2.2.2. Synthesis of [AgNO2(dppm)]2 (2)
Compound 2 has been prepared similarly by using 1
mmol of AgNO2 and 1 mmol of dppm, giving 42% yield
and was recrystallized from methanol as microcrystal-
1
M.p. 194 °C. H NMR (CDCl3, 293 K): d 1.75br (2H,
PCH2CH2CH2P), 2.30t (4H, PCH2CH2CH2P), 7.20–
7.50m (20H, PC6H5). Kmol (CH2Cl2, concentration ¼
1:00 ꢃ 10ꢀ3 M): 2.1 Xꢀ1 cm2 molꢀ1. IR (cmꢀ1): 3071w,
3045w [m(C–H)], 1661w, 1627w [m(NO2)], 1586m, 1573w
[m(C@C)], 1432s, 1417w, 1306m [masym(NO)], 1270w,
1217sbr [msym(NO)], 1152m, 860w, 844w, 823m
[d(ONO)], 520s, 504vs, 482s, 474s, 445m, 422w [m(P–
Ph)], 383m, 357w, 372w, 313m, 280m, 247m, 226m. ESI
MS (MeCN): (+) 933 (100) [Ag(dppp)2]þ. Anal. Calc.
for C27H26AgNO2P4: C, 57.26; H, 4.63; N, 2.47. Found:
C, 56.90; H, 4.88; N, 2.37%.
1
line solids. M.p. 205 °C. H NMR (CDCl3, 293 K): d
3.60s (2H, PCH2P), 7.20–7.48m, 7.44d br (20H, PC6H5).
Kmol (CH2Cl2, concentration ¼ 1.00 ꢃ 10ꢀ3 M): 6.7
Xꢀ1 cm2 molꢀ1. IR (cmꢀ1): 3078w, 3052w [m(C–H)],
1683w, 1661w [m(NO2)], 1586w, 1573w [m(C@C)], 1436s,
1333m [masym(NO)], 1296m, 1278m, 1219sbr [msym(NO)],
1185m, 1159m, 1129m, 860w, 845m, 838sh, 827s
[d(ONO)], 512s, 504vs, 473vs, 452m, 410m [m(P–Ph)],
276m, 256m, 210w. ESI MS (MeCN): (+) 684 (30)
[Ag2NO2(dppm)]þ, 876 (35) [Ag(dppm)2]þ, 1019 (100)
[Ag2Cl(dppm)2]þ, 1144 (30) [Ag3Cl(OH)(dppm)2]þ.
Anal. Calc. for C25H22AgNO2P2: C, 55.79; H, 4.12; N,
2.60. Found: C, 55.51; H, 4.28; N, 2.62%.
2.2.6. Synthesis of [AgNO2(dppb)]2 (6)
Compound 6 was prepared as for 3, using 1 mmol of
AgNO2 and 2.5 mmol of dppb, re-crystallization from
methanol giving a microcrystalline solid in 66% yield.
2.2.3. Synthesis of [AgNO2(dppe)]2 (3)
1
AgNO2 (0.154 g, 1 mmol) was added to a methanol
solution (30 ml) of dppe (0.398 g, 1 mmol), at 40 °C. After
the addition, the solution was stirred for 48 h at 40 °C in
the dark, and then for 2 h at room temperature. A colorless
precipitate formed which was filtered off and washed with
methanol (3 ꢃ 10 ml). Crystallization from methanol gave
complex 3 as a microcrystalline solid in 85% yield. M.p.
M.p. 235 °C. H NMR (CDCl3, 293 K): d 1.5 br (4H,
PCH2CH2CH2CH2P), 2.0 br (4H, PCH2CH2CH2CH2P),
7.10–7.55m, 7.62–7.75m (20H, PC6H5). Kmol (CH2Cl2,
concentration ¼ 1:00 ꢃ 10ꢀ3 M): 8.3 Xꢀ1 cm2 molꢀ1. IR
(cmꢀ1): 3073w [m(C–H)], 1626w [m(NO2)], 1585w, 1570w
[m(C@C)], 1432s, 1304m [masym(NO)], 1271w, 12130m
[msym(NO)], 1178s br, 843m [d(ONO)], 516s, 510s, 478s,
456m, 445m, 409w, 397w [m(P–Ph)], 303m, 278w, 265w,
1
240 °C. H NMR (CDCl3, 293 K): d 2.45–2.55m (4H,

1526
Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
254w, 247w, 225w, 208w. ESI MS (MeCN): (+) 961 (100)
[Ag(dppb)2]þ, 977 (50) [Ag(dppb)2 + (O)]þ. Anal. Calc.
for C52H48AgNO2P4: C, 65.69; H, 5.09; N, 1.47. Found:
C, 65.66; H, 5.39; N, 1.56%.
2.2.10. Synthesis of [AgNO2(R)-Tol-Binap)] (10)
Compound 10 was prepared as for 3, using 1 mmol of
AgNO2 and 1 mmol of R-Tol-Binap in dichlorome-
thane, re-crystallization from methanol giving a micro-
1
crystalline solid in 68% yield. M.p. 252 °C. H NMR
(CDCl3, 293 K): d 1.72s, 1.90s, 2.34s, 2.46s (12H,
CH3C6H4P), 5.80d, 6.24d, 6.76d, 6.91q, 7.01t, 7.15–
7.28m, 7.43d, 7.46d, 7.69q (28H, Haromatic of R-Tol-Bi-
nap). Kmol (CH2Cl2, concentration ¼ 1:00 ꢃ 10ꢀ3 M): K
0.8 Xꢀ1 cm2 molꢀ1. IR (cmꢀ1): 3065w [m(C–H)], 1587w,
1575w [m(C@C)], 1390m, 1337m, 1303m [masym(NO)],
1216s br [msym(NO)], 1179m, 1087m, 869m, 840m, 808s
[d(ONO)], 516sh, 511vs, 497s, 470m, 444m, 428m, 404w,
398m [m(P–Ph)], 352m, 324w, 302w, 279m, 246w, 223m.
ESI MS (MeCN): (+) 1465 (100) [Ag(R-Tol-Binap)2]þ.
Anal. Calc. for C48H40AgNO2P2: C, 69.24; H, 4.84; N,
1.68. Found: C, 68.93; H, 4.98; N, 1.42%.
2.2.7. Synthesis of [AgNO2(dppf)]2 (7)
Compound 7 was prepared as for 3 using 1 mmol of
AgNO2 and 2.5 mmol of dppf, re-crystallization giving a
microcrystalline solid in 80% yield. M.p. 221 °C. 1H
NMR (CDCl3, 293 K): d 4.20–4.40m (8H, C5H5), 7.20–
7.50m, 7.55–7.70m (20 H, PC6H5). Kmol (CH2Cl2,
concentration ¼ 1:00 ꢃ 10ꢀ3 M): 1.2 Xꢀ1 cm2 molꢀ1. IR
(cmꢀ1): 3052w [m(C–H)], 1662w, 1646w [m(NO2)], 1586w,
1571w [m(C@C)], 1434s, 1312m [masym(NO)], 1227m
[msym(NO)], 1196m, 1180m, 1170s, 1160m, 885w, 868w,
835m, 828m [d(ONO)], 536s, 513vs, 490vs, 470s, 456s,
432m, 420m, 399w [m(P–Ph)], 375w, 352m, 327w, 314w,
304w, 283w, 278m, 267w, 253w, 246m, 228w, 223w,
212w. ESI MS (MeCN): (+) 662 (40) [Ag(dppf)]þ, 1216
(100) [Ag(dppf)2]þ, 1232 (20) [Ag(dppf)2 + (O)]þ. Anal.
Calc. for C34H28AgFeNO2P2: C, 57.66; H, 3.98; N, 1.98.
Found: C, 57.43; H, 4.02; N, 1.82%.
2.2.11. Synthesis of [Ag(NO2)(S-Binap)] (11)
Compound 11 was prepared as for 3, using 1 mmol of
AgNO2 and 1 mmol of S-Binap in dichloromethane, re-
crystallization from methanol giving a microcrystalline
1
solid in 77% yield. M.p. 134 °C. H NMR (CDCl3, 293
K): 5.98t, 6.49t, 6.67t, 6.77d, 7.00–7.20m, 7.29t, 7.48–
7.60m, 7.62–7.90m (32H, Haromatic of S-Binap). Kmol
(CH2Cl2, concentration ¼ 1:00 ꢃ 10ꢀ3 M): 0.9 Xꢀ1 cm2
molꢀ1. IR (cmꢀ1): 3075w [m(C–H)], 1584w, 1549w
[m(C@C)], 1432s, 1340m, 1303w, 1275w [m asym(NO)],
1220m [msym(NO)], 1158m, 1148m, 1089m, 870m, 816s
[d(ONO)], 540m, 520s, 506vs, 494s, 450m, 431m, 419w,
398m [m(P–Ph)], 375w, 352w, 329w, 290m, 280m, 266w,
245w. ESI MS (MeCN): (+) 1353 (100) [Ag(S-
BINAP)2]þ, 1369 (20) [Ag(S-Binap)2 + (O)]þ, 1507(3)
[Ag2(NO2)(S- Binap)2]þ. Anal. Calc. for C44H32AgNO2
P2: C, 68.05; H, 4.15; N, 1.80. Found: C, 68.35; H, 4.28;
N, 1.62%.
2.2.8. Synthesis of [(AgNO2)2(dppet)]2 (8)
Compound 8 was prepared as for 3, using 1 mmol of
AgNO2 and 1 mmol of dppet in dichloromethane, re-
crystallization from methanol giving a microcrystalline
solid in 62% yield. M.p. 170 °C. 1H NMR (CDCl3, 293 K):
d 7.22–7.44m (22H, PCH@CHP and PC6H5). Kmol
(CH2Cl2, concentration ¼ 1:00 ꢃ 10ꢀ3 M): 0.9 Xꢀ1 cm2
molꢀ1: IR (cmꢀ1): 3182w [m(C–H)], 1684w, 1653w
[m(NO2)], 1576w [m(C@C)], 1303m [masym(NO)], 1208
[msym(NO)], 1155m br, 890m, 844w [d(ONO)], 556vs, 514s,
500w, 482m, 470w, 461m, 433m, 406w [m(P–Ph)], 371w,
352m, 326w, 315w, 290w, 281w. ESI MS (MeCN): (+) 1467
(100) [Ag2(NO2)(dppet)3 + (O)]þ. Anal. Calc. for C26H22
Ag2N2O4P2; C, 44.35; H, 3.15; N, 3.98. Found: C, 44.73;
H, 3.22; N, 3.80%.
2.2.12. Synthesis of [Ag(NO2)(SS-Diop)] (12)
Compound 12 was prepared as for 3, using 1 mmol of
AgNO2 and 1 mmol of S,S-diop in dichloromethane, re-
crystallization from methanol giving a microcrystalline
2.2.9. Synthesis of [AgNO2(dcpm)]2 (9)
1
Compound 9 was prepared as for 8, using 1 mmol
of AgNO2 and 1 mmol of dcpm in dichloromethane,
re-crystallization from methanol giving a microcrystal-
solid in 63% yield. M.p. 128 °C. H NMR (CDCl3, 293
K):
d 1.30s (6H, CH3DIOP), 2.44dd, 86br (4H,
CH2PDiop), 4.18br (2H, O–CHDiop), 7.22–7.50m, 7.56–
7.82m (20H, Haromatic of S,S-Diop). Kmol (CH2Cl2,
concentration ¼ 1:00 ꢃ 10ꢀ3 M): 0.9 Xꢀ1 cm2 molꢀ1. IR
(cmꢀ1): 3072w, 3048w [m(C–H)], 1658w, 1627w [m(NO2)],
1585w, 1573w [m(C@C)], 1438s, 1339m, 1307m
[masym(NO)], 1221m [msym(NO)], 1212sbr, 1186m, 1174s,
1156m 884s, 846w, 832w [d(ONO)], 5068vs, 472s, 437m,
418m [m(P–Ph)], 347m, 312w, 281w, 264w, 247m, 226m,
211w. ESI MS (MeCN): (+) 1105 (100) [Ag(S,S-
Diop)2]þ, 1121 (25) [Ag(S,S-Diop)2 + O]þ 1258 (10)
[Ag2(NO2)(S,S-Diop)2]þ. Anal. Calc. for C31H32-
AgNO2P2: C, 57.07; H, 4.94; N, 2.15. Found: C, 57.43;
H, 5.06; N, 2.02%.
1
line solid in 57% yield. M.p. 259 °C. H NMR (CDCl3,
293 K): d 1.15–1.40m (22H, PC6H11), 1.68s (2H,
PCH2P), 1.73–1.9m (22H, PC6H11). Kmol (CH2Cl2,
concentration ¼ 1:00 ꢃ 10ꢀ3 M): 0.9 Xꢀ1 cm2 molꢀ1. IR
(cmꢀ1): 1651w, 1644w [m(NO2)], 1447s, 1366m, 1350m,
1327m [masym(NO)], 1295m, 1215m [msym(NO)], 1188s,
1175s, 1149m 887m, 848s, 819m [d(ONO)], 517s br, 492s
br, 471s, 459s, 419m, 398m, 385w, 375w, 351m, 341w,
326w, 303m, 282w, 278w, 267w, 248m, 229m, 221w. ESI
MS (MeCN): (+) 1078 (100) [Ag2(NO2)(dcpm)2]þ. Anal.
Calc. for C25H46AgNO2P2: C, 53.39; H, 8.24; N, 2.49.
Found: C, 53.10; H, 8.35; N, 2.32%.

Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
1527
Table 1
31P{1H} NMR data of compounds 1–12 (CDCl3)
Compound
d(31P)a 295 K
)6.5br
1J(31P–Ag)b
d(31P) 218 K
1J(31P–Ag)
d(31P)freePꢀdonor
)21.5
Dc
1
5.35d
479
15
)3.0d br
)11.95d
)23.7s br
5.11dm
220
470
2
3
4.29dt
4.3br
5.3br
462
242
)21.5
)12.0
25.8
17.3
6.59d
5.17d
442
445
4
5
3.2dbr
1.5br
5.77dbr
0.51dd
249
)12.0
)16.8
15.2
18.3
413 (107Ag)
477 (109Ag)
418
6
7
8
0.3br
1.9d
)1.5d
)4.09dd
)15.5
)16.8
)22.8
15.8
12.9
14.8
405
)3.9dbr
)8.04br
387 (107Ag)
447 (109Ag)
255
4.21
)7.59
19.8dm
14.1dd
718
9
10
21.1dt
13.0dd
461
239
463
)9.5
)11.5br
30.6
24.5
23.1
380 (107Ag)
438 (109Ag)
225 (107Ag)
258 (109Ag)
224.0–258.2
343–394
406
11.6d br
13.9dd
11
12
15.8d
12.9d
241
360
372
16.9dd
15.2dd
)9.8d
)9.7d
)15.2
)23.0
31.0
28.1
13.3
)9.7dbr
407
a d in ppm.
b J in Hz.
c D ¼ d(31P)complex ) d(31P)freeP
.
2.3. X-ray crystallographic studies
153 K) yielding NtðotalÞ reflections, merging to N unique
(Rint cited) after ÔempiricalÕ/multiscan absorption cor-
rection (proprietary software), No being considered
ÔobservedÕ and used in the full matrix least squares re-
finements. Anisotropic displacement parameter forms
Full spheres of CCD area detector diffractometer
data were measured (Bruker AXS instrument, x-scans;
monochromatic Mo Ka radiation, k ¼ 0:71073 A; T ca.
ꢁ
were refined for the non-hydrogen atoms, (x; y; z; Uiso H
)
being included, constrained at estimates. Conventional
residuals R, Rw (weights: ðr2ðF Þ þ 0:0004F 2Þꢀ1) are cited
on jF j at convergence. Neutral atom complex scattering
factors were employed within the XTAL 3.7 program
system [19]. Pertinent results are given below and in
Tables 3–6 and Figs. 8–11, the latter showing 50%
probability amplitude displacement envelopes for the
non-hydrogen atoms, hydrogen atoms having arbitrary
Table 2
31P CPMAS NMR dataa
Compound
d(31P)b
1J(31P–Ag)c
1
12.52m
)0.81m
)24.95m
)4.19
7.05d
7.12d
439
478
370
444
488
449
439
440
2
5
ꢁ
radii of 0.1 A. CCDC 219656–219659.
6
7
8
)0.87d
)1.29
)0.10br
)12.63d
30.25d
21.68d
1.12br
)2.01br
)5.03br
7.0m
683
469
498
3. Results and discussion
9
10
3.1. Syntheses
The reaction of AgNO2 with 2.5 equiv of bis(diph-
enylphosphino)methane (dppm) in methanol at 60 °C
gave rise to compound 1 [Ag2(dppm)3](NO2)2 which
presumably is analogous to the structurally character-
ized [Ag2(dppm)3](NO3)2 (Fig. 2(a)) [20]. When the
AgNO3:dppm (1:1)
498
459
0.70m
a (mr ¼ 10 KHz).
b d in ppm.
c J in Hz.

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Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
Table 3
Crystal/refinement data
2a
5
8b
10c
Compound
AgNO2:(Ph2P)2CH2
(1:1)2 ꢄ MeOH
AgNO2:(Ph2PCH2)2CH2
(1:1)2
AgNO2:(Ph2PCH)2
(2:1)2
AgNO2:(p-tol2
P(C10H6)2)2 (1:1)
Formula
Mr
Crystal system
C
1140.6
52H52Ag2N2O6P4
C54H52Ag2N2O4P4
1132.7
triclinic
C52H44Ag4N4O8P4
1408.3
monoclinic
C48H40AgNO2P2
832.7
triclinic
monoclinic
P21=n (C25h, No. 14)
11.2048(8)
19.651(1)
1
1
ꢂ
ꢂ
Space group
ꢁ
P1 (Ci , No. 2)
10.530(1)
10.738(1)
12.850(2)
114.041(2)
90.180(2)
110.180(2)
1228
P21=n
P1 (C1 , No. 1)
11.2603(8)
13.3239(9)
14.945(1)
64.916(2)
76.980(2)
73.861(2)
1936
a (A)
12.2451(7)
10.4164(6)
20.025(1)
ꢁ
b (A)
ꢁ
c (A)
11.2534(8)
a (°)
b (°)
c (°)
V (A )
Dc (g cmꢀ3
99.218(2)
91.932(2)
3
ꢁ
2446
1.549
2553
1.832
)
1.531
1 dimer
0.98
1.425
Z
2 dimers
0.98
2 f.u.
1.7
2
0.65
lMo (mmꢀ1
)
Specimen (mm3)
ÔTÕmin=max
2hmax(°)
0.16 ꢃ 0.11 ꢃ 0.07
0.88
68
0.35 ꢃ 0.22 ꢃ 0.15
0.89
58
0.55 ꢃ 0.25 ꢃ 0.025
0.25 ꢃ 0.16 ꢃ 0.10
0.86
58
0.73
75
Nt
51,470
9986 (0.070)
6251
14,342
53,361
13,313 (0.060)
8290
39,753
N (Rint
No
)
5999 (0.023)
4875
0.047
9024 (0.027)
7823
0.048
R
Rw
0.048
0.050
0.042
0.042
0.053
0.056
a Difference map residues were modelled in terms of methanol of solvation, the oxygen disordered over a pair of sites, occupancies set at 0.5 after
trial refinement. Associated hydrogen atoms were not located.
b (x, y, z, Uiso
) were refined.
H
c High displacement parameters/disorder were evident in the two nitrite groups; disorder was resolved and refined in the N, O(1) component of
nitrite 1, occupancies set at 0.5 after trial refinement, with isotropic displacement parameter forms. ÔFriedelÕ data were preserved distinct, xabs refining
to )0.03(3), the chirality as shown in Fig. 2 the same for the two independent molecules in the asymmetric unit and consistent with that expected for
the ligand as supplied.
Table 4
Selected geometries, AgNO2:(p-tolyl2P(C10H6)2Pp-tolyl2) (1:1) (10)
Atoms
Parameter
Atoms
Parameter
2.31(2)a, 2.35(1)
2.40(2), 2.39(1)
ꢁ
Bond distances (A)
Ag(n)–P(n1)
Ag(n)–P(n2)
2.426(3), 2.438(2)
2.490(2), 2.455(3)
Ag(n)–O(n1)
Ag(n)–O(n2)
Bond angles (°)
P(n1)–Ag(n)–P(n2)
96.00(8), 99.07(9)
139.1(4)a, 139.0(2)
132.8(3), 119.3(2)
104.8(3), 102.6(2)
116.4(4) 113.3(3)
115.7(3), 123.3(2)
104.2(4), 106.2(4)
107.7(4), 104.0(5)
107.1(4), 105.8(4)
P(n2)–Ag(n)–O(n1)
P(n2)–Ag(n)–O(n2)
119.6(4)a, 121.2(2)
111.4(3), 118.2(3)
54.2(5)a, 49.9(3)
108.8(2), 107.1(3)
117.0(3), 113.9(4)
113.6(3, 115.5(3)
107.4(4), 105.0(4)
106.6(4), 106.0(5)
102.7(4), 108.5(4)
P(n1)–Ag(n)–O(n1)
P(n1)–Ag(n)–O(n2)
Ag(n)–P(n1)–C(n112)
Ag(n)–P(n1)–C(n121)
Ag(n)–P(n1)–C(n131)
C(n112)–P(n1)–C(n121)
C(n112)–P(n1)–C(n131)
C(n121)–P(n1)–C(n131)
O(n1)–Ag(n)–O(n2)
Ag(n)–P(n2)–C(n212)
Ag(n)–P(n2)–C(n221)
Ag(n)–P(n2)–C(n231)
C(n212)–P(n2)–C(n222)
C(n212)–P(n2)–C(n232)
C(n222)–P(n2)–C(n232)
Torsion angles (°) (carbon atoms denoted by number only)
Ag(n)–P(n1)–n112–n111
Ag(n)–P(n1)–n121–n122
Ag(n)–P(n1)–n131–n132
n112–n111–n211–n212
76.4(9), 73.4(7))
–11.2(7), 35.3(9)
4.0(6), 8.5(10)
)77(1), )83(1)
Ag(n)–P(n2)–n212–n211
Ag(n)–P(n2)–n211–n222
Ag(n)–P(n2)–n231–n232
68.3(6), 66.0(8)
)19.3(7), 21.4(9)
11(1), 10.4(7)
The two values in each entry are for molecules 1,2.
0
a
0
0
ꢁ
Ag(1)–O(11 ) is 2.42(2) A; P(11,12)–Ag–O(11 ) are 143.7(3), 119.9(3) and O(12)–Ag–O(11 ) 41.0(5)°.
reaction between AgNO2 and dppm was carried out
with a 1:1 ligand to metal ratio, the dinuclear compound
[Ag2(dppm)2(NO2)2] 2 formed (Fig. 2(b)) (see below,
X-ray discussion). 1,2-Bis(diphenylphosphino)ethane
(dppe) forms both 1:1 (3) and 2:1 (4) adducts depending
on the ligand stoichiometry employed. Only 1:1 adducts

Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
1529
Table 5
Selected geometries, AgNO2:(Ph2P(CH2)nPPh2) (1:1)2 (n ¼ 1; 3) (2 and 5)
Atoms
Parameter
Atoms
Parameter
ꢁ
Bond distances (A)
Ag–P(1)
2.4346(9), 2.422(1)
2.4536(9), 2.450(1)
3.1877(4), 4.5737(9)
Ag–O(1)
Ag–O(2)
2.694(4), 2.559(5)
2.475(3), 2.481(7)
4.311(4), 3.127(4)
6.444(5), 3.426(7)
Ag–P(20)
Agꢄ ꢄ ꢄAg0
Agꢄ ꢄ ꢄO(10)
O(1)ꢄ ꢄ ꢄO(10)
Bond angles (°)b
P(1)–Ag–P(20)
P(1)–Ag–O(1)
148.28(3), 143.67(4)
127.90(8), 113.3(1)
107.24(8), 112.2(2)
113.6(1), 111.7(2)
116.0(1), 115.8(2)
113.0(1), 115.5(1)
104.0(2), 104.6(2)
103.8(2), 100.8(2)
105.2(2), 106.9(2)
110.1(2)
P(20)–Ag–O(1)
P(20)–Ag–O(2)
82.99(8), 100.3(1)
99.33(8), 100.9(2)
47.9(1), 45.6(2)
P(1)–Ag–O(2)
Ag–P(1)–C(1)
O(1)–Ag–O(2)
Ag0–P(2)–C(1,2)
Ag0–P(2)–C(211)
Ag0–P(2)–C(221)
C(1,2)–P(2)–C(211)
C(1,2)–P(2)–C(221)
C(211)–P(2)–C(221)
108.2(1), 107.5(1)
119.8(1), 117.8(2)
114.8(1), 118.3(1)
103.9(2), 104.4(2)
103.1(9), 102.9(2)
105.2(2), 104.1(2)
Ag–P(1)–C(111)
Ag–P(1)–C(121)
C(1)–P(1)–C(111)
C(1)–P(1)–C(121)
C(111)–P(1)–C(121)
P(1)–C(1)–P(2)
Torsion angles (°) (carbon atoms denoted by number only)
Ag–P(1)–1–P(2),12
Ag–P(1)–111–112
Ag–P(1)–121–122
)33.6(2), )42.7(3)
)5.0(3), )0.5(3)a
)68.7(3), )58.2(3)a
Ag0–P(2)–1,2–P(1),12
Ag0–P(2)–211–212
Ag0–P(2)–221–222
68.6(2), 59.7(3)
)1.2(3), 17.7(4)
65.8(3), 67.0(5)
Primed atoms are inversion related; the two values in each entry are for n ¼ 1; 3, respectively.
a For 112 read 116.
b In 5, angles C(1,12,2) are 112.9(3)°, 111.9(4)°, 110.3(3)°.
Table 6
Selected geometries, AgNO2:(Ph2PCH:CHPPh2) (2:1)2 (8)
Atoms
Parameter
Atoms
Parameter
ꢁ
Bond distances (A)
Ag(1)–P(1)
2.3651(7)
2.332(2)
2.286(2)
1.239(4)
1.259(4)
3.7923(4)
1.337(4)
Ag(2)–P(2)
2.3786(7)
2.249(3)
2.426(2)
2.522(2)
1.275(3)
1.233(3)
2.8463(3)
Ag(1)–O(11)
Ag(1)–O(210)
N(1)–O(11)
Ag(2)–O(12)
Ag(2)–O(21)
Ag(2)–O(22)
N(2)–O(21)
N(2)–O(22)
Ag(1)ꢄ ꢄ ꢄAg(2)
N(1)–O(12)
Ag(2)ꢄ ꢄ ꢄAg(20)
C(1)–C(2)
Bond angles (°)
P(1)–Ag(1)–O(11)
P(1)–Ag(1)–O(210)
O(11)–Ag(1)–O(210)
R
Ag(1)–O(11)–N(1)
Ag(2)–O(12)–N(1)
O(11)–N(1)–O(12)
O(21)–N(2)–O(22)
N(2)–O(21)–Ag(10)
Ag(2)–O(22)–N(2)
122.36(7)
146.59(5)
90.90(8)
359.85
P(2)–Ag(2)–O(12)
P(2)–Ag(2)–O(21)
P(2)–Ag(2)–O(22)
O(12)–Ag(2)–O(21)
O(12)–Ag(2)–O(22)
O(21)–Ag(2)–O(22)
Ag(2)–O(21)–N(2)
Ag(2)–O(21)–Ag(10)
P(1)–C(1)–C(2)
150.97(7)
121.28(5)
112.30(6)
87.64(8)
83.39(8)
50.09(7)
100.0(2)
145.57(7)
126.5(1)
125.6(2)
123.5(2)
136.4(2)
116.1(3)
113.4(2)
113.7(2)
96.5(2)
P(2)–C(2)–C(1)
Primed atoms are inversion related.
(5–7, 9) between AgNO2 and 1,3-bis(diphenylphosph-
ino)propane (dppp), 1,4-bis(diphenylphosphino)butane
(dppb), 4,40-bis(diphenylphosphino)ferrocene (dppf) or
bis(dicyclohexylphosphino)methane (dcpm), have been
obtained, respectively, independently of reaction con-
ditions and ligand-to-metal ratio employed. The chiral
ligands R-Tol-Binap, S,S-Binap and S,S-Diop also form
1:1 adducts (10–12), all probably possessing a mono-
nuclear structure (Fig. 2(c)). The cis-1,2-bis(diph-
enylphosphino)ethylene ligand (dppet) is the only donor
molecule which forms a tetranuclear adduct (8) adduct
having a 1:2 ligand to metal ratio.
The complexes 1–6, and 9 are air-stable, colorless
materials, soluble in polar solvents such as acetonitrile,
dimethylformamide and dimethylsulfoxide. They are,
however, insoluble in water, ether and tetrahydrofuran
but exhibit good solubility in the chlorinated hy-
drocarbons CH2Cl2 and CHCl3. Solid samples and

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Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
more complex in accordance with the NO2-coordina-
ONO
Ph
tion as depicted in Fig. 3. Conductivity measurements
in CH2Cl2 confirm the ionic nature of 4, whereas the
lack of conductivity found in CH2Cl2 for adduct 1 is
explicable with the occurrence of equilibria such as (1),
also supported from the 31P NMR solution data (see
below).
Ph
P
Ph
Ph
Ph
(a)
Ph
Ph
P
Ag
P
P
Ph
Ph
P
Ag
P
Ph
Ph
Ph
ONO
½Ag2ðdppmÞ ꢅðNO2Þ ¢ ½Ag2ðNO2Þ ðdppmÞ ꢅ þ dppm
3
2
2
2
1
2
N
O
O
Ag
Ag
OO
N
ð1Þ
R
P
R
R
P
R
R
P
P
R
1
R
Ag
In the H NMR spectra of 1–12 in CDCl3 (see Sec-
tion 2), the signals due to the diphosphine show a dif-
ferent pattern with respect to those found for the free
donors, confirming the existence, at least partial, of the
complexes in solution. The bridging methylene reso-
nances in 1–6 and 9 appear as a broad singlet or mul-
tiplet between 2.50 and 3.60 ppm downfield shifted with
respect to those found in the free donors.
O
O
N
n(H2C)
(CH2)n
P
R R
P
R R
R
(b)
(c)
Fig. 2. Molecular Structure of compounds 2 (a), 9 (b) and 10.
solutions of these compounds show no sensitivity to
light. Compounds 7, 8, 10–12 are generally unstable in
solution, their chlorinated solvent solutions often
darkening in a very short time. Derivatives 10–12 exhibit
also high sensitivity to light.
31P chemical shifts (CDCl3 solution) and 31P–Ag
coupling-constants for derivatives 1–12, are reported in
Table 1. They have been found to be slightly dependent
on the dilution of the solutions. Our experiments have
been carried out at a concentration of 0.005 mol/L. The
room temperature 31P NMR spectra of complexes 3, 5, 6
and 8 consist of broad singlets, presumably in conse-
quence of exchange equilibria that are reasonably fast in
relation to the NMR time scale. Exchange is quenched
at low temperature (218–223 K), and one and/or two
unresolved doublets or resolved pairs of doublets, aris-
ing from coupling between the phosphorus and silver
atom, are observed in the accessible temperature range.
In particular, in the spectrum of derivative 5 typical
pairs of doublets, due to 1J(31P–107Ag) and 1J(31P–
109Ag) coupling, are resolved at 218 K and the observed
1J(107Ag)/1J(109Ag) ratio is in good agreement with that
calculated from the gyromagnetic ratio of the Ag nuclei
3.2. Spectroscopy
The infrared spectra of 1–12 (see Section 2) are con-
sistent with the formulations proposed, showing all of
the bands required by the presence of the nitrito group
and of the phosphorus donor [21–24]. In some cases in
the complexes the bands due to the phosphine ligands,
only slightly shifted with respect to those of the free
donors, are not resolved due to the presence of the very
intense nitrite band in the same region. In the far-IR
spectra of all derivatives 1–12 we assigned, on the basis
of a previous report on phosphino silver(I) derivatives
[25], the broad absorptions near 500 cmꢀ1 and those at
450–400 cmꢀ1 to WhiffenÕs y and t vibrations, respec-
tively. Some bands in the region 400–300 cmꢀ1, similar
to those described in the literature for triphenylphos-
phine silver(I) nitrate derivatives [25], can be tentatively
assigned to m(Ag–P) and m(Ag–O) vibrations.
c(107Ag)/c(109Ag) [28]. For derivatives
7 and 12
such doublets were also observed at room temperature,
suggesting that rapid exchange equilibria are not oper-
ative in the cases of sterically hindered phosphines such
as dppf and S,S-Diop. The signal due to each free
phosphine is always up-field with respect to that of the
In the spectra of our compounds 2, 3, 5–12 the ab-
sorptions due to masym and msym fall in the range 1330–
1290 and 1220–1200 cmꢀ1, respectively, as expected for
an O,O0-chelating NO2 group. However it has been
previously proposed that the two metal–oxygen dis-
tances of a chelated nitrite can differ significantly, the
detectable effect being the splitting of the sharp peak
due to d(NO2) and a widening of the energy separation
between masym and msym [26,27]. Both effects have been
observed in our compounds, the lower separation be-
tween masym and msym and non-splitting of d(NO2) being
found for the derivative 10 also, in accordance with the
X-ray data (see below). The spectrum of compound 8 is
N
O
P
O
Ag
P
O
Ag
P
N
Ag
O
O
O
O
Ag
N
P
N
O
Fig. 3. Silver coordination environment in compound 8.

Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
1531
corresponding silver(I) complex. The magnitudes of D
(D ¼ d31Pcomplex ) d31Pfree ligand) and the coupling con-
stants decrease with the decreasing basicity, also corre-
lating with steric bulk and bite of the ligands. It is
worthy of note that the presence of two different dou-
blets having the same 31P-Ag coupling constants in the
case of compounds 3, 6 and 12, suggests the existence of
different isomers or species in solution. Muetterties and
Alegranti [29] and Goel and Pilon [30] indicated that the
spin–spin constant (J) between phosphorus and silver
changes, depending on the number of coordinated
phosphorus atoms in the silver complex, and that it is
possible to determine the number of the latter from
measurement of the J values in the 31P NMR spectra.
On the basis of the detected values, an AgP2O2 coor-
dination environment is likely in solution for com-
pounds 3, 5–8 and 12, consistent with the structures
found in the solid state. The 31P NMR spectra of the R-
Tol-Binap and S,S-Binap compounds 10 and 11 exhibit
two double doublets, the peaks having the same inten-
sities both at low and room temperature. We have
compared our data with those reported by Yamagishi
for Ag(PF6)(S-Binap) systems [31]. The signals at 13.9
and 16.9 ppm in the low temperature spectra of 10 and
11 respectively can be assigned to a silver center pre-
sumably four-coordinated by a pairs of Binap ligands,
whereas those at 14.1 (10) and 15.2 (11), for which
greater 1J(Ag–P) coupling constants were detected,
could arise from a silver coordinated by two phosphorus
atoms as in the solid state (see below). This means that
the presence of an anion more coordinating with respect
to PF6 can modify the concentration in solution of those
species active toward the Mukaiyama aldol reaction [8–
10]. Molecular weight measurements carried out for
compound 2 indicate the existence of 2 as a dinuclear
species also in CHCl3 solution, r ( ¼ ratio between ex-
perimental and calculated formula weight) being 1.96 at
10ꢀ2 m. The 31P NMR spectra of compounds 2 and 9
support this finding. A double triplet and a broad signal
have been found at room temperature (Fig. 4(a)),
whereas the low temperature 31P spectrum consists of an
AA0XX0A00Aꢆ pattern (Fig. 4(b)) [32] due to the non-
equivalence of the phosphorus atoms (as emerges also
2
from the X-ray data) and resulting from the large J(P–
P), for the three possible combinations of the two silver
isotopes. It is very interesting that the same pattern,
differ from that previously reported [20], has been found
by us also for the well known [Ag2(dppm)2(NO3)2]
species. The 31P NMR spectrum of 1 confirms the oc-
currence of equilibrium (1), four different signals being
detected at low temperature, the first due to free dppm,
the second unambiguously assignable to compound 2
and a third due to a silver center coordinated by only
one phosphorus atom. Finally the 31P NMR spectrum
of 4 is in accordance with a tetrahedral silver center
four-coordinated, presumably by a pair of chelating
1
dppe ligands, the J(Ag–P) coupling constant being in
the range typical for AgP4 cores [29,30].
Fig. 4. 31P NMR spectrum (CDCl3 solution) of 2 at 22 °C (a) and 55 ° C (b).

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Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
The solid state 1D 31P CPMAS and 2D 31P CPCOSY
Fig. 5(d) exhibits a partially resolved (overlapping)
doublet structure. This is corroborated by the corre-
sponding 2D 31P CPCOSY spectrum of Fig. 6(a) which
shows the two partially resolved doublets as clearly re-
solved correlations, one above and one below the main
NMR spectra are shown in Figs. 5 and 6, respectively.
The isotropic chemical shifts and 1J(Ag–P) heteronu-
clear coupling constants measured for this suite of
complexes are given in Table 2. From Fig. 5(a) and (b),
the P positions in the dimeric complexes [AgNO2-
(dppb)]2 (6) and [AgNO2(dppf)]2 (7) are equivalent, thus
giving rise to a single well-resolved doublet in each case.
1
diagonal with J(Ag–P) values of ꢁ488 Hz (low field)
and ꢁ449 Hz (high field). These correlations are poorly
formed and are indicative of an overall reduction in
symmetry as experienced with tightly coupled
AA0XX0A00Aꢆ or AA0XX0BB0 spin systems.
1
The measured J(Ag–P) coupling constants are 439 and
449 Hz, respectively. This symmetry is somewhat lower
for the [AgNO2(dppm)]2 (2) dimer, where a marked re-
duction in resolution is exhibited in the solid state (see
Fig. 5(c)). Although, doublet structure is evident with a
1J(Ag–P) value of ꢁ444 Hz, it is much broader than that
observed for 6 and 7 and is consistent with the
The 1D 31P CPMAS spectrum of the dimeric com-
plex [AgNO2(dcpm)]2 (9) shown in Fig. 5(e) is a well-
resolved example of an AA0XX0BB0 spin system. The
1J(Ag–P) coupling constants of 469 Hz (low field) and
1
498 (high field) are consistent with other J(Ag–P) val-
AA0XX0A00Aꢆ spin system elucidated from the above 31
P
solution NMR studies. A further reduction in symmetry
is observed for the [AgNO2-(dppp)]2 (5) dimer, where
ues measured in these 1:1 dimers, and the component of
each doublet exhibits quartet additional fine structure
thus indicating homonuclear 2J(P–P) coupling to the
Fig. 5. Solid state 1D 31P CPMAS of derivatives 6 (a), 7 (b), 2 (c), 5 (d), 9 (e), dppm:AgNO3 1:1 (f), 1 (g) and 8 (h).

Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
1533
Fig. 6. Solid state 2D 31P CPCOSY NMR spectra of derivatives 5 (a), 9 (b), dppm:AgNO3 1:1 (c) and 1 (d).
other P positions. This coupling is corroborated by the
associated 2D 31P CPCOSY spectrum of Fig. 6(b) which
shows well-formed correlations above and below the
main diagonal. A similar scenario is observed for the
[AgNO3(dppm)]2 dimer [20] in Fig. 5(f). This example is
more resolved in the 1D CPMAS spectrum, yielding
1J(Ag–P) coupling constants of 498 Hz (low field) and
459 Hz (high field) which are comparable to those
measured for the corresponding NO2 dimers. However,
the 2D 31P CPCOSY result of Fig. 6(c) exhibits poorly
formed, diffuse off-diagonal correlations that suggest an
analogous AA0XX0BB0 spin system where less precise
chemical shift overlap is being observed in comparison
to the [AgNO2(dcpm)]2 (9) case. The 3:2 complex
[(AgNO2)2(dppm)3] (1) shown in Fig. 5(g) is a more
complicated extension of this type of spin system, and
probably warrants an AA0XX0BB0CC0 description. An
earlier synthesis of the [(AgNO3)2(dppm)3] analogue [2]
demonstrated that the NO3 anion was non-coordinating
and that the trigonal planar, tri-bridged dimer gener-
ated near-chemical equivalence amongst all six P posi-
tions. In this NO2 example no such chemical
equivalence amongst the P sites is evident; from
Fig. 5(g) it is readily observed that significant chemical
shift differences exist between the three resolved 31P
resonances. This chemical shift range is >35 ppm, and
the spectrum describes a system where a significant re-
duction in symmetry has been induced, probably by the
direct coordination of NO2 onto this tri-bridged dimer.
The higher field resonance at )24.95 ppm is associated
with the P positions that would be directly affected by
such a coordination, while the other shifts at )0.81 ppm
and 12.52 ppm are expected to be those positions with
diphenyl substituents only. The P sites bearing diphenyl
substituents yield 1J(Ag–P) coupling constants of 439
Hz (low field) and 478 Hz (high field) which are con-
sistent with the above mentioned measurements. How-
ever, the NO2 influenced P position exhibits a reduced
1J(Ag–P) value of ꢁ 370 Hz. The 2D 31P CPCOSY
spectrum of Fig. 6(d) displays correlations from each P
site to all other P sites thus confirming this trigonal
planar-type connectivity.

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Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
Fig. 7. ESI MS spectrum of derivative 2.
The positive electrospray mass spectra of complexes
3.3. X-ray discussion
1–12 (the most relevant data are reported in Section 2
and a typical spectrum is reported in Fig. 7) indicate that
these derivatives always undergo loss of the anionic
NO2ꢀ ligand. The isotopic distribution of these species is
in accord with the calculated composition. The aggre-
gation behavior is strongly dependent on the stoichi-
ometry of the adducts, but differs from that previously
found for triorganophosphine adducts, in this case being
independent of the solvent employed, no adducts con-
taining CH3CN being detected also at concentration
10ꢀ4 M, no significant differences being found between
the spectra carried out in CH3CN and those in acetone.
Under our conditions in the case of dppm and dcpm li-
gands, aggregates containing two silver atoms, two di-
phosphine donors and one NO2 group dominate
significantly over adducts containing one, three or more
silver atoms, whereas all other ligands seem to favor in
solution aggregates containing only one silver center
four-coordinated by two diphosphine donors In some
cases oxidation of the phosphine is also evident. It is
interesting to note that the behavior of dppet is unique,
the most abundant ion being that containing two silver
atoms, one NO2 and three P2-donors, as in the solid-state
structure of [Ag2(dppm)3]2þ. No fragments containing
two positive charges have been detected. As previously
reported by us the negative electrospray spectra are al-
ways dominated by the presence of molecular peaks due
to [AgCl2]ꢀ, [Ag(NO2)2]ꢀ, [Ag2(NO2)3]ꢀ [33].
The results of the low-temperature single crystal X-
ray structure determinations are consistent with the
formulation of the adducts formed between silver(I)
nitrite and bidentate diphosphine ligands Ph2P(CH2)n-
PPh2 (n ¼ 1, 3) (2, 5) and p-tolyl2P(C10H6)2P-p-tolyl2
(10) as complexes of 1:1 stoichiometry, the former being
centrosymmetric dimers with one AgNO2:L formula
unit comprising the asymmetric unit of the structure, the
latter a mononuclear chiral species, two molecules of
similar chirality comprising the asymmetric unit of the
structure, the absolute configuration as determined be-
ing consistent with that expected for the ligand as sup-
plied. The adduct (8) formed with Ph2PCH:CHPPh2 is
tetranuclear, also centrosymmetric, of 2:1 AgNO2:L
stoichiometry, one such formula unit comprising the
asymmetric unit of the structure. The crystal packings in
a number of the arrays show features of interest.
The two crystallographically independent molecules of
AgNO2:p-tolyl2P(C10H6)2Pp-tolyl2 (1:1) (10) are closely
similar (Fig. 8), with quasi-2 symmetry, the putative 2-axis
passing through N, Ag and the mid-point of the binaph-
thyl central bond, the symmetry being broken principally
by ill-behaved nitrite groups in both molecules. Interest-
ingly, the principal difference between the two molecules
occurs in respect of the inclinations of ring 2 at each
phosphine; within each molecule, the pair conform to 2-
symmetry, but are twisted (in concert?) in one molecule

Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
1535
Fig. 9. Projection of the dimer AgNO2:(Ph2PCH2PPh2) (1:1)2 (2).
Fig. 8. Projection of molecule 1 of mononuclear AgNO2:(p-
tolyl2PC10H6C10H6. Pp-tolyl2) (1:1) (10) normal to their AgP2 planes.
relative to the other (Table 4). The environments of the
silver atoms are bis(chelate) in each case, the chelates
being one of small (NO2) and one of large (L) bite. A
recent report [27] has described the observation of similar
P2Ag(O2N) environments in the context of unidentate
tertiary phosphine donors PR3 for R ¼ Ph, cy, o-tolyl (all
153 K studies); Ag–P are 2.4303(6), 2.4325(6); 2.459(1),
ꢁ
2.461(1); 2.4416(5), 2.4437(5) A, with P–Ag–P 129.57(2),
132.03(5), 148.04(2)°, respectively. In the present context
of a bidentate ligand P–Ag–P is constrained to a much
smaller value than the above; despite this Ag–P are very
similar. (The (not unusual) difficulties associated with the
modelling of the nitrite group preclude meaningful com-
ment on relevant geometries associated with it.) Ag–P–
C(binap) are considerably smaller than Ag–P–C(Ph).
The two adducts AgNO2:Ph2P(CH2)nPPh2 (1:1)2
(n ¼ 1, 3) (2, 5) (Figs. 9 and 10) take a similar form; both
are centrosymmetric dimers, in which the diphosphine
ligand bridges the two silver atoms, a nitrite chelating
each of the latter. In each case, the nitrite plane lies
approximately normal to the line joining the mid-points
of the two ligands, O(1) directed toward the centro-
symmetrically related silver, albeit at a long distance,
with the possibility in the n ¼ 3 case that the
O(1)ꢄ ꢄ ꢄO(10) interaction is repulsive. Despite differences
in P–Ag–P, the Ag–P distances are similar and similar to
those discussed in the context of the unidentate mono-
nuclear species above. The methylene bridge aside, li-
gand conformations (about the phosphorus atoms) are
remarkably similar in the two complexes.
Fig. 10. Projection of the dimer AgNO2: Ph2P(CH2)3 PPh2 (1:1)2 (5).
Adducts of the form MX:EPh3 (1:1) (MX ¼ coinage
metal(I) halide) are commonly tetrameric, occurring in
the ÔcubaneÕ or ÔchairÕ forms [34]. A recent study of
AgBrO3:PPh3 (1:1) shows it also to be tetrameric, with a
structure loosely based on the ÔchairÕ tetramer, the cen-
tral l3-halides being supplanted by l2-bridging oxygens
from bromate oxyanions, with a second oxygen from
each performing the third bridging function to a pe-
ripheral metal atom; the peripheral l2-halides are re-
placed by OꢄBrOꢄO anions, the two donor oxygens
bonded to central and peripheral silver-atoms, respec-
tively [35]. The present AgNO2:(Ph2PCH:CHPPh2) (2:1)
adduct 8 (Fig. 9, Table 5) is a further variation on that
theme, corresponding more nearly to having an origin in
the MX:Ph2PCH2PPh2 (2:1)2 adducts which are also

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Effendy et al. / Inorganica Chimica Acta 357 (2004) 1523–1537
be ionic as in the derivative [Ag(dppe)2]NO2, or bridi-
ging tridentate as in [(AgNO2)2(dppet)]2, or finally
chelating as in [(AgNO2)2(dppm)2] and [(AgNO2)2
(dppp)2], where the two Ag–O distances are sensibly
different, and in [AgNO2(R)-Tol-Binap)] where the two
Ag–O distances are closer.
Acknowledgements
This work was supported by University of Camerino,
MIUR and Carima Foundation.
Fig. 11. Projection of tetranuclear AgNO2: (Ph2PCH:CHPPh2) (2:1)2
(8).
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