Syntheses and spectroscopic and structural characterization of silver(I) complexes containing tris(isobutyl)phosphine and poly(azol-1-yl)borates

Article abstract of DOI:10.1016/j.ica.2004.06.020

Silver(I) derivatives [Ag(L)(PⁱBu₃)] have been synthesized from the reaction of [Ag(NO₃)(PⁱBu ₃)₂] with scorpionate ligands and characterized both in solution (¹H- and ³¹P{¹H}NMR, ESI MS spectroscopy, conductivity) and in the solid state (IR, single crystal X-ray structure analysis). ³¹P{¹H} NMR variable temperature studies showed that in the pz⁰Tp^x derivatives the scorpionate ligand acts as a bidentate donor, whereas tridentate coordination is found for all tris(azolyl)borate derivatives, both in solution and in the solid state. Silver(I) derivatives [Ag(L)(PⁱBu₃)] (L = H ₂B(tz)₂ (dihydrobis(1H-1,2,4-triazol-1-yl)borate), HB(tz)₃ (hydrotris(1H-1,2,4-triazol-1-yl)borate), Tp (hydrotris(1H-pyrazol-1-yl)borate), Tp* (hydrotris(3,5-dimethyl-1H- pyrazol-1-yl)borate), Tp^Me (hydrotris(3-methyl-1H-pyrazol-1-yl) borate), Tp^CF3 (hydrotris(3-trifluoromethyl-1H-pyrazol-1-yl)borate), Tp^4Br (hydrotris(4-bromo-1H-pyrazol-1-yl)borate), HB(btz)₃ (hydrotris(1H-1,2,4-benzotriazol-1-yl)borate), Tm (hydrotris(3-methy-1- imidazolyl-2-thione)borate), pzTp (tetrakis(1H-pyrazol-1-yl)borate), pz ⁰Tp^Me (tetrakis(3-methyl-1H-pyrazol-1-yl)borate) have been synthesized from the reaction of [Ag(NO₃)(PⁱBu ₃)₂] with ML (M = Na or K) and characterized both in solution (¹H- and ³¹P{¹H} NMR, ESI MS spectroscopy, conductivity) and in the solid state (IR, single crystal X-ray structure analysis). These complexes are air-stable and light-sensitive and non-electrolytes in CH₂Cl₂ and acetone in which they slowly decompose, even with the strict exclusion of oxygen and light, yielding metallic silver and/or azolate (Az) species of formula [Ag(Az)(P ⁱBu₃)_x] upon breaking of the bridging B-N _(azole) bond. The solid state structures of [Ag(Tp)(P ⁱBu₃)], [Ag(Tp^Me)(PⁱBu ₃)], [Ag(Tp^CF3)(PⁱBu₃)], [Ag{HB(btz)₃}(PⁱBu₃)], and [Ag(Tm)(P ⁱBu₃)] show that the silver atom adopts a distorted tetrahedral coordination geometry. [Ag(L)(PPh₃)] can be easily obtained from the reaction of [Ag(L)(PⁱBu₃)] with excess PPh₃, whereas from the reverse reaction of [Ag(L)(PPh₃)] with PⁱBu₃a mixture of [Ag(L)(PⁱBu ₃)] and [Ag(L)]₂ and [Ag(L)(PPh₃)] was recovered. ³¹P{¹H} NMR variable temperature NMR studies showed that in the pz⁰Tp^x derivatives the scorpionate ligand acts as a bidentate donor, whereas tridentate coordination is found for all tris(azolyl)borate derivatives, both in solution and in the solid state. ESI MS data suggest the existence in solution of species such as [Ag(P ⁱBu₃)₂]⁺ upon dissociation of the L ligand, and also the formation of dimeric species of the form [Ag ₂(L)(PⁱBu₃)₂]⁺.

Full text of DOI:10.1016/j.ica.2004.06.020

Inorganica Chimica Acta 357 (2004) 4247–4256
www.elsevier.com/locate/ica
Syntheses and spectroscopic and structural characterization
of silver(I) complexes containing tris(isobutyl)phosphine
and poly(azol-1-yl)borates
c
c
c
Effendy a,b, Giancarlo Gioia Lobbia , Fabio Marchetti , Maura Pellei ,
c,
c
c
Claudio Pettinari *, Riccardo Pettinari , Carlo Santini ,
b
Brian W. Skelton , Allan H. White
b
a
Jurusan Kimia, FMIPA Universitas Negeri Malang, Jalan Surabaya 6, Malang 65145, Indonesia
Department of Chemistry, The University of Western Australia, Crawley, WA 6009, Australia
`
Dipartimento di Scienze Chimiche, Universita degli Studi di Camerino, via S. Agostino 1, 62032 Camerino MC, Italy
b
c
Received 19 April 2004; accepted 12 June 2004
Available online 30 July 2004
Abstract
Silver(I) derivatives [Ag(L)(PiBu3)] (L=H2B(tz)2 (dihydrobis(1H-1,2,4-triazol-1-yl)borate), HB(tz)3 (hydrotris(1H-1,2,4-triazol-
1-yl)borate), Tp (hydrotris(1H-pyrazol-1-yl)borate), Tp (hydrotris(3,5-dimethyl-1H-pyrazol-1-yl)borate), TpMe (hydrotris(3-me-
*
thyl-1H-pyrazol-1-yl)borate), TpCF3 (hydrotris(3-trifluoromethyl-1H-pyrazol-1-yl)borate), Tp4Br (hydrotris(4-bromo-1H-pyrazol-
1-yl)borate), HB(btz)3 (hydrotris(1H-1,2,4-benzotriazol-1-yl)borate), Tm (hydrotris(3-methy-1-imidazolyl-2-thione)borate), pzTp
(tetrakis(1H-pyrazol-1-yl)borate), pz0TpMe (tetrakis(3-methyl-1H-pyrazol-1-yl)borate) have been synthesized from the reaction of
[Ag(NO3)(PiBu3)2] with ML (M=Na or K) and characterized both in solution (1H- and 31P{1H} NMR, ESI MS spectroscopy, con-
ductivity) and in the solid state (IR, single crystal X-ray structure analysis).These complexes are air-stable and light-sensitive and
non-electrolytes in CH2Cl2 and acetone in which they slowly decompose, even with the strict exclusion of oxygen and light, yielding
metallic silver and/or azolate (Az) species of formula [Ag(Az)(PiBu3)x] upon breaking of the bridging B–N(azole) bond.The solid state
structures of [Ag(Tp)(PiBu3)], [Ag(TpMe)(PiBu3)], [Ag(TpCF3)(PiBu3)], [Ag{HB(btz)3}(PiBu3)], and [Ag(Tm)(PiBu3)] show that
the silver atom adopts a distorted tetrahedral coordination geometry.[Ag(L)(PPh3)] can be easily obtained from the reaction of
[Ag(L)(PiBu3)] with excess PPh3, whereas from the reverse reaction of [Ag(L)(PPh3)] with PiBu3 a mixture of[Ag(L)(PiBu3)] and
[Ag(L)]2 and [Ag(L)(PPh3)] was recovered. 31P{1H} NMR variable temperature NMR studies showed that in the pz0Tpx derivatives
the scorpionate ligand acts as a bidentate donor, whereas tridentate coordination is found for all tris(azolyl)borate derivatives, both
in solution and in the solid state. ESI MS data suggest the existence in solution of species such as [Ag(PiBu3)2]+ upon dissociation of
the L ligand, and also the formation of dimeric species of the form [Ag2(L)(PiBu3)2]+.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Scorpionates; Silver(I); Triorganophosphines; X-ray; 31P NMR; ESI MS
1. Introduction
Since the first report of Trofimenko [1], poly(pyrazo-
lyl)borates or scorpionate ligands [2], have been exten-
*
Corresponding author. Tel.: +39-0737-402234; fax: +39-0737-
sively employed as anionic r-donor ligands in a
wide variety of metal complexes [3]. These ligands are
637345.
E-mail address: claudio.pettinari@unicam.it (C. Pettinari).
0020-1693/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2004.06.020

4248
Effendy et al. / Inorganica Chimica Acta 357 (2004) 4247–4256
extremely versatile because the number of pyrazolate
groups and the substituents thereon or at the B center
can be readily modified in order to obtain ligands with dif-
ferent steric and/or electronic profiles. They have been
extensively used to synthesize complexes of main and
transition group metals and they are particularly useful
for the synthesis of monomeric derivatives in which the
coordination sphere of the metal can be carefully control-
led [4–9]. Important modifications to poly(pyrazolyl)bor-
ates can be made by changing the substituents on the
heterocyclic ring or also by replacement of the pyrazolyl
rings with triazolyl [10], benzotriazolyl [11], imidazolyl
[12,13], and methimazolyl moieties [14–21]. These
replacements have led to new scorpionates able to bridge
between different metal centers, yielding dimers or coordi-
nation polymers characterized by peculiar spectroscopic
and structural features. Some of these new ligands are
very promising for the synthesis of inorganic materials
with inner cavities useful for the catalysis of organic reac-
tions [22,23] or with collective magnetic phenomena for
the design of molecular-based ferromagnets [24].
We have recently initiated an investigation into the
structural and spectroscopic properties of mixed phos-
phine/N-donor derivatives of copper(I) [25], silver(I)
[26–32] and gold(I) [33]. As a part of this study we have
been interested in the exploration of complexes incorpo-
rating poly(azolyl)borate and phosphine ligands with
different steric and electronic profiles. In our research
concerning modifications of the poly(pyrazolyl)borate
ligands in which the pyrazolyl rings are replaced by
1,2,4-triazolyl or imidazolyl rings, some interesting sin-
gle-stranded silver(I) coordination polymers containing
bridging poly(1-imidazolyl)borates have been reported
[30].
We have also previously reported the substitution of
triazole for pyrazole in poly(pyrazolyl)alkanes to form
poly(triazolyl)alkanes such as the bis(1,2,4-triazolyl)alk-
ane ligand, able to coordinate silver(I) salts through the
nitrogen atoms, yielding two- and three-dimensional
coordination polymers [34]. We have now extended this
work to the investigation of different N- or S-donor
scorpionate ligands with silver(I) salts in the presence
of competitor phosphine ligands, in order to build new
complexes with different solid state structure and prop-
erties. Here we describe the results of the interaction
of various bis- and tris-(azolyl)borate ligands with
AgNO3 in the presence of the tris(isobutyl)phosphine
coligand.
ard Schlenk techniques or a glove box. All solvents were
dried, degassed and distilled prior to use. All chemicals
were purchased from Aldrich and used without further
purification. Potassium dihydrobis(1H-1,2,4-triazol-1-
yl)borate K[H2B(tz)2], potassium hydrotris(1H-1,2,4-tri-
azol-1-yl)borate K[HB(tz)3] [25], sodium hydrotris(1H-
pyrazol-1-yl)borate Na(Tp) [35], potassium hydro-
tris(3,5-dimethyl-1H-pyrazol-1-yl)borate K(Tp ) [35],
*
sodium
hydrotris(3-methyl-1H-pyrazol-1-yl)borate
Na(TpMe), potassium tetrakis(1H-pyrazol-1-yl)borate
K(pzTp) [35], potassium tetrakis(3-methyl-1H-pyrazol-
1-yl)borate K(pz0TpMe) [35], sodium hydrotris(3-tri-
fluoromethyl-1H-pyrazol-1-yl)borate Na(TpCF3
) [36],
potassium hydrotris(4-bromo-1H-pyrazol-1-yl)borate
K(Tp4Br) [37,38], potassium hydrotris(1H-1,2,4-benzo-
triazol-1-yl)borate, K[HB(btz)3] [39] and potassium
hydrotris(3-methy-1-imidazolyl-2-thione)borate, K(Tm)
[26] were synthesized in accordance with literature meth-
ods. Elemental analyses (C, H, N, S) were performed in
house with a Fisons Instruments 1108 CHNS-O Ele-
mental Analyser. IR spectra (selected data are available
as Supplementary material) were recorded from 4000 to
100 cmꢀ1 with a Perkin–Elmer System 2000 FT-IR
1
instrument. H, and 31P NMR spectra were recorded
1
on a VXR-300 Varian spectrometer (300 MHz for H,
and 121.4 MHz for 31P). H chemical shifts are reported
in ppm versus SiMe4, P chemical shifts in ppm versus
H3PO4 85%. The electrical conductances of the acetone,
dichloromethane, DMSO and acetonitrile solutions
were measured with a Crison CDTM 522 conductimeter
at room temperature. Positive and negative electrospray
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 rea-
gent grade acetone or acetonitrile. For the ESI-MS data,
masses and intensities were compared to those calcu-
lated by using the IsoPro isotopic abundance simulator
version 2.1 [40]; peaks containing silver(I) ions are iden-
tified as the centers of isotopic clusters.
2.2. Syntheses
2.2.1. [Ag(NO3)(PiBu3)2]
PiBu3 (0.809 g, 4.0 mmol) was added at room temper-
ature, under an atmosphere of dry oxygen-free dinitro-
gen, to an anhydrous THF solution (20 ml) of AgNO3
(0.338 g, 2.0 mmol). After the addition, the solution
was stirred under an atmosphere of dry oxygen-free
dinitrogen for 24 h and subsequently the solvent was re-
moved with a rotary evaporator. n-hexane (30 ml) was
added; a brown precipitate was formed, which was fil-
tered off and washed with n-hexane to give complex
[Ag(NO3)(PiBu3)2] as a colorless micro-crystalline solid
2. Experimental
2.1. Materials and methods
1
All syntheses and handling were carried out under an
atmosphere of dry oxygen-free dinitrogen, using stand-
in 85% yield, m.p. 73–76 ꢁC. H NMR (CDCl3, 293
K): d 0.99 (sbr, 6H, CH2CH–(CH3)2), 1.58 (sbr, 2H,

Effendy et al. / Inorganica Chimica Acta 357 (2004) 4247–4256
4249
CH2CH–(CH3)2), 1.81 (br, 1H, CH2CH–(CH3)2).
1
C, 41.1; H, 6.5; N, 24.0. Found: C, 41.5; H, 6.8; N,
23.5%.
31P{1H} NMR (CDCl3, 293 K): d ꢀ13.64 (dd, J(31P,
107Ag)=480 Hz, 1J(31P, 109Ag)=554 Hz). IR (nujol,
cmꢀ1): 812s (NO3). ESI MS (+): 511 [100] [Ag(PiBu3)2]+.
(ꢀ) 62.2 [90] (NO3)ꢀ, 230.9 [100] [Ag(NO3)2]ꢀ. Anal.
Calc. for C24H54AgNP2O3: C, 50.2; H, 9.5; N, 2.4.
Found: C, 49.8; H, 9.8; N, 2.3%.
2.2.4. [Ag{Tp}(PiBu3)] (3)
Compound 3 was prepared similarly to compound 1,
by using Na(Tp) (0.236 g, 1 mmol) and [Ag(NO3)(Pi-
Bu3)2] (0.574 g, 1.0 mmol); it was re-crystallized from
methanol/CHCl3 (2:1) to give complex 3 as a colorless
micro-crystalline grey solid in 75% yield, m.p. 119–122
ꢁC. 1H NMR (CDCl3, 293 K): d 1.11 (d, 18H,
CH2CH–(CH3)2), 1.61 (pt, 6H, CH2CH–(CH3)2), 1.98
(m, 3H, CH2CH–(CH3)2), 6.10 (t, 3H, 4-CH), 7.43 (d,
3H, 5-CH), 7.65 (d, 3H, 3-CH). 31P{1H} NMR (CDCl3,
293 K): d ꢀ11.22 (d, 1J(31P, Ag)=629 Hz; 31P{1H}
2.2.2. [Ag{H2B(tz)2}(PiBu3)] (1)
K[H2B(tz)2] (0.188 g, 1.0 mmol) was added at room
temperature to a methanol solution (30 ml) of [Ag-
(NO3)(PiBu3)2] (0.574 g, 1.0 mmol). After the addition,
the solution was stirred for 2 h and subsequently the sol-
vent was removed with a rotary evaporator. Chloroform
(30 ml) was added. The suspension was filtered and the
solution was concentrated under reduced pressure.
Diethyl ether (30 ml) and n-hexane (20 ml) were then
added; a colorless precipitate was formed, which was fil-
tered off and washed with diethyl ether/n-hexane. Re-
crystallization from chloroform/methanol (1:2) gave
complex 1 as a colorless micro-crystalline solid in 78%
1
NMR (CDCl3, 218 K): d ꢀ8.72 (d, J(31P, Ag)=636
Hz). IR (nujol, cmꢀ1): 2457s (BH). ESI MS (+): 511
[100] [Ag(PiBu3)2]+, 833.7 [90] [Ag2{Tp}(PiBu3)2]+; (ꢀ)
231.9 [20] {Tp}ꢀ. Anal. Calc. for C21H37AgBN6P: C,
48.2; H, 7.1; N, 16.1. Found: C, 48.4; H, 7.5; N, 15.8%.
2.2.5. [Ag{TpMe}(PiBu3)] (4)
1
yield, m.p. 104–107 ꢁC. H NMR (CDCl3, 293 K): d
Compound 4 was prepared similarly to compound 1,
by using Na[HB(3-Mepz)3] (0.278 g, 1 mmol) and [Ag-
(NO3)(PiBu3)2] (0.574 g, 1.0 mmol); it was re-crystallized
from CHCl3/n-hexane (1:1) to give complex 4 as a color-
less micro-crystalline solid in 76% yield, m.p. 151–154
1.12 (d, 18H, CH2CH–(CH3)2), 1.63 (pt, 6H, CH2CH–
(CH3)2), 1.90 (m, 3H, CH2CH–(CH3)2), 7.86 (s, 2H, 5-
CH), 8.14 (s, 2H, 3-CH). 31P{1H} NMR (CDCl3, 293
K): d ꢀ14.69 (br); 31P{1H} NMR (CDCl3, 218 K): d
1
1
1
ꢀ15.3 (dd, J(31P, 107Ag)=626 Hz, J(31P, 109Ag)=721
Hz). IR (nujol, cmꢀ1): 2418s (BH). Anal. Calc. for
C16H33AgBN6P: C, 41.9; H, 7.2; N, 18.3. Found: C,
42.3; H, 7.6; N, 18.0%. Silver(I) derivatives [Ag(scorp-
ionate)(PiBu3)] have been synthesized from the reaction
of [Ag(NO3)(PiBu3)2] with sodium or potassium scorp-
ionate salts and characterized both in solution and in
the solid state.
ꢁC. H NMR (CDCl3, 293 K): d 1.04, 1.08 (dbr, 18H,
CH2CH–(CH3)2), 1.60 (br, 6H, CH2CH–(CH3)2), 1.90
(mbr, 3H, CH2CH–(CH3)2), 2.24 (s, 9H, 3-CH3), 5.86
1
(d, 3H, 4-CH), 7.50 (d, 3H, 5-CH); H NMR (CDCl3,
223 K): d 1.00, 1.08 (d, 18H, CH2CH–(CH3)2), 1.60
(br, 6H, CH2CH–(CH3)2), 1.95 (mbr, 3H, CH2CH–
(CH3)2), 2.22 (s, 9H, 3-CH3), 5.87 (d, 3H, 4-CH), 7.51
(d, 3H, 5-CH). 31P{1H} NMR (CDCl3, 293 K): d
ꢀ18.74 (dd, 1J(31P, 107Ag)=590 Hz, 1J(31P,
109Ag)=680 Hz); 31P{1H} NMR (CDCl3, 218 K): d
ꢀ23.12 (dd, 1J(31P, 107Ag)=591 Hz, 1J(31P,
109Ag)=681 Hz). IR (nujol, cmꢀ1): 2409m (BH). Anal.
Calc. for C24H43AgBN6P: C, 51.0; H, 7.7; N, 14.9.
Found: C, 49.6; H, 8.0; N, 14.5%.
2.2.3. [Ag{HB(tz)3}(PiBu3)] (2)
K[HB(tz)3] (0.255 g, 1.0 mmol) was added at room
temperature to a methanol solution (30 ml) of [Ag-
(NO3)(PiBu3)2] (0.574 g, 1.0 mmol). After the addition,
the solution was stirred for 2 h. and subsequently the
solvent was removed with a rotary evaporator. Chloro-
form (30 ml) was added. The suspension was filtered and
the solution was concentrated under reduced pressure.
Diethyl ether (30 ml) was added; a yellow precipitate
was formed, which was filtered off and washed with
diethyl ether/n-hexane. Re-crystallization from metha-
nol/CHCl3 (2:1) gave complex 2 as a colorless micro-
crystalline solid in 44% yield, m.p. 119–122 ꢁC. 1H
NMR (CDCl3, 293 K): d 1.10 (d, 18H, CH2CH–
(CH3)2), 1.66 (pt, 6H, CH2CH–(CH3)2), 1.95 (m, 3H,
CH2CH–(CH3)2), 7.89 (s, 3H, 5-CH), 8.27 (s, 3H, 3-
CH). 31P{1H} NMR (CDCl3, 293 K): d ꢀ12.31 (dd,
1J(31P, 107Ag)=629 Hz, 1J(31P, 109Ag)=716 Hz);
2.2.6. [Ag{TpCF3}(PiBu3)] (5)
Compound 5 was prepared similarly to compound 1,
by using Na(TpCF3) (0.440 g, 1 mmol) and [Ag(NO3)(Pi-
Bu3)2] (0.574 g, 1.0 mmol); it was re-crystallized from
CHCl3/methanol (1:1) to give complex 5 as a colorless
micro-crystalline solid in 65% yield, m.p. 125–129 ꢁC.
1H NMR (CDCl3, 293 K): d 0.99, 1.10 (d, 18H,
CH2CH–(CH3)2), 1.55, 1.60 (d, 6H, CH2CH–(CH3)2),
1.84, 2.11 (mbr, 3H, CH2CH–(CH3)2), 6.42 (d, 3H, 4-
CH), 7.66 (d, 3H, 5-CH). 31P{1H} NMR (CDCl3, 293
K): d ꢀ17.25 (dd, 1J(31P, 107Ag)=654 Hz, 1J(31P,
109Ag)=749 Hz); 31P{1H} NMR (CDCl3, 218 K): d
ꢀ24.01 (dd, 1J(31P, 107Ag)=649 Hz, 1J(31P,
109Ag)=746 Hz). IR (nujol, cmꢀ1): 2457s (BH). ESI
MS (+): 511 [100] [Ag(PiBu3)2]+, 1038 [20]
1
31P{1H} NMR (CDCl3, 218 K): d ꢀ10.9 (dd, J(31P,
107Ag)=624 Hz, 1J(31P, 109Ag)=719 Hz). IR (nujol,
cmꢀ1): 2483m (BH). Anal. Calc. for C18H34AgBN9P:

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Effendy et al. / Inorganica Chimica Acta 357 (2004) 4247–4256
[Ag2{TpCF3}(PiBu3)2]+; (ꢀ) 417 [10] {TpCF3}ꢀ,434 [40]
[Ag{NO3}2(PiBu3)]ꢀ. Anal. Calc. for C24H34AgBF9N6P:
C, 39.6; H, 4.7; N, 11.6. Found: C, 40.3; H, 5.0; N,
11.2%.
C, 53.3; H, 6.0; N, 18.6. Found: C, 53.0; H, 6.2; N,
18.3%.
2.2.10. [Ag{Tm}(PiBu3)] (9)
Compound 9 was prepared similarly to compound 1,
by using KTm (0.390 g, 1 mmol), and [Ag(NO3)(PiBu3)2]
(0.574 g, 1.0 mmol); it was re-crystallized from CHCl3/
methanol (1:2) to give complex 9 as a colorless micro-
crystalline solid in 92% yield, m.p. 185–188 ꢁC. 1H
NMR (CDCl3, 293 K): d 1.03 (d, 18H, CH2CH–
(CH3)2), 1.51 (pt, 6H, CH2CH–(CH3)2), 1.94 (m, 3H,
CH2CH–(CH3)2), 3.60 (s, 9H, CH3), 6.67 (d, 3H, CH),
6.77 (d, 3H, CH). 31P{1H} NMR (CDCl3, 293 K): d
ꢀ15.34 (d, 1J(31P, Ag)=529 Hz); 31P{1H} NMR
2.2.7. [Ag{Tp4Br}(PiBu3)] (6)
Compound 6 was prepared similarly to compound 1,
by using K(Tp4Br) (0.488 g, 1 mmol), and [Ag(NO3)(Pi-
Bu3)2] (0.574 g, 1.0 mmol); it was re-crystallized from
CHCl3/methanol (1:1) to give complex 6 as a colorless
micro-crystalline solid in 73% yield, m.p. 215–217 ꢁC.
1H NMR (CDCl3, 293 K): d 1.12 (d, 18H, CH2CH–
(CH3)2), 1.61 (pt, 6H, CH2CH–(CH3)2), 1.96 (m, 3H,
CH2CH–(CH3)2), 7.36 (s, 3H, 5-CH), 7.63 (s, 3H, 3-
CH). 31P{1H} NMR (CDCl3, 293 K): d ꢀ12.36 (dd,
1J(31P, 107Ag)=614 Hz, 1J(31P, 109Ag)=707 Hz);
1
107
(CDCl3, 218 K): d ꢀ23.56 (dd, J(31P, Ag)=460 Hz,
1J(31P, 109Ag)=530 Hz). IR (nujol, cmꢀ1): 2379m
(BH). ESI MS (+): 769 (45) [Ag2{Tm}(PiBu3)]+. Anal.
Calc. for C24H43AgBN6PS3: C, 43.6; H, 6.5; N, 12.7;
S, 14.7. Found: C, 43.2; H, 7.2; N, 12.4; S, 14.4%.
31P{1H} NMR (CDCl3, 218 K): d ꢀ10.74 (dd, J(31P,
1
107Ag)=613 Hz, 1J(31P, 109Ag)=708 Hz). IR (nujol,
cmꢀ1): 2413m (BH). Anal. Calc. for C21H34AgBBr3N6P:
C, 33.2; H, 4.5; N, 11.1. Found: C, 33.3; H, 4.8; N,
11.0%.
2.2.11. [{B(pz)4}Ag(PiBu3)] (10)
Compound 10 was prepared similarly to compound
1, by using K[B(pz)4] (0.319 g, 1 mmol) and [(PiBu3)Ag-
NO3] (0.574 g, 1.0 mmol); it was re-crystallized from
CHCl3/n-hexane (1:1) to give complex 10 as a colorless
micro-crystalline solid in 63% yield, m.p. 98–100 ꢁC.
1H NMR (CDCl3, 293 K): d 1.04, 1.10 (d, 18H,
CH2CH–(CH3)2), 1.50 (pt, 6H, CH2CH–(CH3)2), 1.79
(br, 3H, CH2CH–(CH3)2), 6.22 (t, 4H, 4-CH), 7.09 (d,
4H, 3- or 5-CH), 7.63 (d, 4H, 3- or 5-CH). 31P{1H}
NMR (CDCl3, 293 K): d ꢀ10.5 (dbr); 31P{1H} NMR
2.2.8. [Ag{Tp }(PiBu )] (7)
Compound 7 was prepared similarly to compound 1,
*
3
by using K[HB(3,5-Me2Pz)3] (0.336 g,
1 mmol),
and [Ag(NO3)(PiBu3)2] (0.574 g, 1.0 mmol); it was re-
crystallized from CHCl3/methanol (1:1) to give complex
7 as a colorless micro-crystalline solid in 47% yield, m.p.
1
174–178 ꢁC. H NMR (CDCl3, 293 K): d 1.06, 1.12 (d,
18H, CH2CH–(CH3)2), 1.53, 1.67 (pt, 6H, CH2CH–
(CH3)2), 1.90–2.05 (mc, 3H, CH2CH–(CH3)2), 2.19 (s,
9H, CH3), 2.37 (s, 9H, CH3), 5.66 (s, 3H, 4-CH).
1
(CDCl3, 218 K): d ꢀ9.98 (dd, J(31P, 107Ag)=618 Hz,
31P{1H} NMR (CDCl3, 293 K): d ꢀ19.75 (dd, J(31P,
1J(31P,
109Ag)=713
Hz).
Anal.
Calc.
for
1
107Ag)=585 Hz, 1J(31P, 109Ag)=675 Hz); 31P{1H}
C24H39AgBN8P: C, 48.9; H, 6.7; N, 19.0. Found: C,
49.2; H, 7.0; N, 18.8%.
NMR (CDCl3, 218 K):
107Ag)=586 Hz, 1J(31P, 109Ag)=677 Hz). IR (nujol,
d
ꢀ24.90 (dd, 1J(31P,
cmꢀ1): 2516m (BH). 511 [100] [Ag(PiBu3)2]+, 917 [80]
2.2.12. [{B(3-Mepz)4}Ag(PiBu3)] (11)
[Ag {Tp }(PiBu ) ]+; (ꢀ) 417 [10] {TpCF3}ꢀ,434 [40]
Compound 11 was prepared similarly to compound
1, by using K[B(3-Mepz)4] (0.374 g, 1 mmol) and [(Pi-
Bu3)AgNO3] (0.574 g, 1.0 mmol); it was re-crystallized
from CHCl3/n-hexane (1:1) to give complex 11 as a col-
orless micro-crystalline solid in 72% yield, m.p. 117–120
ꢁC. 1H NMR (CDCl3, 293 K): d 1.02 (d, 18H, CH2CH–
(CH3)2), 1.51 (pt, 6H, CH2CH–(CH3)2), 1.73 (m, 3H,
CH2CH–(CH3)2), 2.28 (s, 9H, CH3), 5.95 (d, 4H, 4-
CH), 7.03 (d, 4H, 5-CH). 31P{1H} NMR (CDCl3, 293
K): d ꢀ14.58 (dd, 1J(31P, 107Ag)=616 Hz, 1J(31P,
109Ag)=702 Hz); 31P{1H} NMR (CDCl3, 218 K): d
ꢀ16.42 (dd, 1J(31P, 107Ag)=610 Hz, 1J(31P,
109Ag)=704 Hz). Anal. Calc. for C28H47AgBN8P: C,
52.1; H, 7.3; N, 17.4. Found: C, 51.7; H, 7.5; N, 17.0%.
*
2
3 2
[Ag{NO3}2(PiBu3)]ꢀ. Anal. Calc. for C27H49AgBN6P:
C, 53.4; H, 8.1; N, 13.8. Found: C, 53.0; H, 8.3; N,
13.5%.
2.2.9. [Ag{HB(btz)3}(PiBu3)] (8)
Compound 8 was prepared similarly to compound 1,
by using K[HB(btz)3] (0405 g, 1 mmol), and [Ag(NO3)-
(PiBu3)2] (0.574 g, 1.0 mmol); it was re-crystallized from
CHCl3/methanol (1:2) to give complex 8 as a colorless
micro-crystalline solid in 92% yield, m.p. 177–181 ꢁC.
1H NMR (CDCl3, 293 K): d 1.16 (d, 18H, CH2CH–
(CH3)2), 1.77 (br, 6H, CH2CH–(CH3)2), 2.13 (br, 3H,
CH2CH–(CH3)2), 7.26–8.08 (mc, 12H, CH). 31P{1H}
NMR (CDCl3, 293 K):
107Ag)=659 Hz, 1J(31P, 109Ag)=748 Hz); 31P{1H}
d
ꢀ15.19 (dd, 1J(31P,
2.3. Structure determinations
NMR (CDCl3, 218 K):
107Ag)=653 Hz, 1J(31P, 109Ag)=754 Hz). IR (nujol,
cmꢀ1): 2477m (BH). Anal. Calc. for C30H40AgBN9P:
d
ꢀ18.87 (dd, 1J(31P,
Full spheres of CCD area-detector diffractometer
data were measured (Bruker AXS instrument, x-scans;

Effendy et al. / Inorganica Chimica Acta 357 (2004) 4247–4256
4251
Table 1
Crystal/refinement data
Compound
3b
4
5
8
9
Formula
Mr (Da)
C
523.2
21H37AgBN6P
C24H43AgBN6P
565.3
C24H34AgBF9N6P
727.2
C30H40AgBN9P
676.4
cubic
C24H43AgBN9PS3
661.5
rhombohedral
Crystal system
Space group
monoclinic
P21/c (No. 14)
8.5920(5)
17.245(1)
17.340(1)
94.524(1)
2561
monoclinic
P21/c (No. 14)
13.199(2)
11.978(2)
18.200(2)
91.435(2)
2876
monoclinic
P21/c (No. 14)
15.864(2)
9.877(1)
60.410(8)
93.963(2)
9443
a
ꢀ
ꢀ
Pa3 (No. 205)
18.877(2)
R3 (No. 148)
15.121(1)
˚
a (A)
˚
b (A)
˚
c (A)
23.360(2)
b (ꢁ)
3
˚
V (A )
6740
1.336 (8)
0.68
4626
1.425(6)
0.93
Dcalc (gcmꢀ3) (Z (f.u.))
1.357(4)
0.87
1.305 (4)
0.78
1.534 (12)
0.77
lMo (mmꢀ1
)
Specimen (mm)
Tmin/max
2hmax (ꢁ)
Nt
0.36·0.20·0.17
0.86
75
0.34·0.08·0.06
0.86
58
0.16·0.06·0.05
0.90
53
0.25·0.15·0.12
0.90
70
0.24·0.22·0.18
0.87
51030
13350
87447
59530
2858 (0.038)
2317
32145
N(Rint
No
R
)
13245 (0.025)
10178
0.029
3369 (0.029)
3160
0.032
19296 (0.075)
13813
0.073
4536 (0.029)
3951
0.029
0.035
0.056
Rw
a
0.086
0.044
0.10
0.041
Hexagonal setting.
Refinement on F2.
b
˚
monochromatic Mo Ka radiation, k=0.71073 A; T ca.
153 K) yielding Nt(otal) reflections, these merging to N
unique (Rint cited) after ÔempiricalÕ/multiscan absorption
correction, No with F>4r(F) considered ÔobservedÕ and
used in the full matrix least squares refinements, refining
anisotropic displacement parameter forms for the non-
interaction of one equivalent of [Ag(NO3)(PiBu3)2]
freshly prepared with one equivalent of K(HnB(tz)4 ꢀ n
(n=1 or 2), M(Tpx) (M=Na or K; Tp=Tp, Tp , TpMe
TpCF3, Tp4Br), M(pz0Tpx) (M=Na or K, pz0Tpx =pzTp
or pz0TpMe), K(Tm) and K(HB(btz)3) in organic sol-
vents at room temperature, complexes 1–11 have been
obtained in high yield (Eq. 1)
)
,
*
hydrogen atoms, (x,y,z,Uiso H included constrained at
)
estimates. Conventional residuals R, Rw on jFj are
quoted at convergence (weights: (r2(F)+0.0004F2)ꢀ1),
neutral atom complex scattering factors being employed
within the XTAL 3.7 program system [41]. Pertinent re-
sults are given in Tables 1 and 2 and Fig. 1, the latter
showing 50% probability amplitude displacement ellip-
soids for the non-hydrogen atoms, hydrogen atoms
½AgðNO3ÞðPiBu3Þ ꢁ þ ML
2
! ½AgðLÞðPiBu3Þꢁ þ MðNO3Þ þ PiBu3
ð1Þ
The derivatives [Ag(NO3)(PiBu3)2] and 1–11 show
good solubility in chlorinated solvents, but are insoluble
in diethyl ether, aliphatic and aromatic hydrocarbons.
They are non-electrolytes in acetone, acetonitrile,
DMSO and CH2Cl2 solution. In the former solvent the
conductivity values are always less than 2.0
Xꢀ1 cm2 molꢀ1. They are air-stable and somewhat
light-sensitive. With exception of 1, 2, 8, 10 and 11 the
chloroform solutions of the scorpionate complexes often
rapidly darken, even with strict exclusion of oxygen and
light. In complexes 3–7 containing Tpx ligands, this is
presumably due to the strong reducing power of the bor-
ate anion (retaining one hydrogen in the Tp derivatives)
which immediately converts the complex into metallic
silver, in accordance with the following Eq. 2:
˚
where shown having arbitrary radii of 0.1 A. In 5, con-
siderable disorder is evident, all modelled in terms of
pairs of components of site occupancies set at 0.5 after
trial refinement for the i-butyl groups of molecule 1 (pre-
sumably concerted) by inversion of the secondary car-
bons, and CF3 groups 113, 123, by rotation about the
C–C(ring) pendant. The very long primitive axis pre-
sented some difficulty in data acquisition.
3. Results and discussion
2½AgðTpÞðPiBu3Þꢁ ! H2 þ 2Ag þ ½BðpzÞ ꢁ
3.1. Syntheses and spectroscopy
3 2
þ 2PiBu3
ð2Þ
An excess of PiBu3 reacts with AgNO3 under an
atmosphere of dry oxygen-free dinitrogen yielding [Ag-
(NO3)(PiBu3)2] in high yields. Further, no other com-
pounds were identified in the reaction mixture also when
a large excess of the P-donor was employed. From the
In some cases colorless powders were recovered from
the chloroform solutions of 3–7. These have been pre-
liminarily identified as a mixture of [Ag(pzx)(PiBu3)n]
and [Ag(PiBu3)n(Hpzx)(NO3)] complexes (n=1 or 2;

4252
Effendy et al. / Inorganica Chimica Acta 357 (2004) 4247–4256
Table 2
Selected molecular geometries
Cpd/mol
4
5
5/1,2,3
9
10a
˚
Distances (A)
Ag–P
2.3469(3)
2.379(1)
2.348(1)
2.361(1)
0.250(3)
0.059(3)
0.282(3)
2.345(1)
2.431(5)
2.298(5)
2.415(5)
1.350(9)
0.118(10)
0.250(10)
2.378(2), 2.380(2), 2.391(2)
2.475(6), 2.424(7), 2.423(6)
2.393(6), 2.407(6), 2.433(6)
2.410(6), 2.458(7), 2.460(6)
0.28(1), 0.55(2), 0.52(1)
0.04(1), 0.17(1), 0.43(2)
0.03(1), 0.43(1), 0.38(2)
2.3783(6)
2.432(2)
2.4035(6)
2.5953(3)
Ag–N(12)
Ag–N(22)
Ag–N(32)
dAg(1)b
dAg(2)
0.014(3)
2.337(3)
dAg(3)
Angles (ꢁ)
P–Ag–N(12)
113.82(3)
128.38(3)
129.60(3)
84.09(4)
79.99(4)
82.45(4)
110.4(1)
110.8(1)
110.1(1)
123.4(1)
135.8(1)
131.4(1)
81.3(2)
128.2(1), 131.1(2), 133.6(1)
131.3(2), 133.4(2), 133.3(2)
134.1(2), 129.9(2), 128.4(2)
82.2(2), 81.2(2), 80.1(2)
132.83(4)
78.86(6)
109.0(2)
118.19(1)
99.51(1)
112.6(1)
P–Ag–N(22)
P–Ag–N(32)
N(12)–Ag–N(22)
N(12)–Ag–N(32)
N(22)–Ag–N(32)
N(11)–B–N(21)
N(11)–B–N(31)
N(21)–B–N(31)
84.0(2)
82.5(2)
80.2(2), 81.1(2), 79.2(2)
81.4(2), 80.3(2), 82.0(2)
112.6(5)
108.2(5)
110.6(5)
110.6(6), 111.8(7), 111.6(7)
111.3(6), 110.8(6), 110.4(7)
111.5(6), 108.3(6), 110.4(7)
Torsion angles (ꢁ)
N(trans)–Ag–P–C(111)
N(trans)–Ag–P–C(211)
N(trans)–Ag–P–C(311)
Ag–P–C(111)–C(112)
Ag–P–C(211)–C(212)
Ag–P–C(311)–C(312)
P–C(111)–C(112)–H(112)
P–C(211)–C(212)–H(212)
P–C(311)–C(312)–H(312)
a
161.55(6)
170.58(6)
162.37(6)
43.8(1)
31.0(1)
61.7(1)
41
163.7(3)
169.4(3)
173.3(3)
52.0(6)
50.0(4)
51.2(5)
42
ꢀ158.3(7)/166.9(5), 164.5(4), ꢀ171.7(3)
ꢀ162.8(6)/168.1(6), 166.9(4), ꢀ165.6(4)
ꢀ155.6(6)/170.0(6), 167.8(5), ꢀ165.5(3)
ꢀ56(2)/57(1), 49.8(9), ꢀ49.7(7)
ꢀ55(1)/53(1), 52.6(8), ꢀ47.1(6)
ꢀ56(2)/54(1), 50.6(11), ꢀ61.2(6)
ꢀ50/34, 42, ꢀ45
ꢀ1.4(1)c
28.5(2)
ꢀ56
ꢀ164.18(6)
ꢀ31.9(4)
46
ꢀ53
39
45
ꢀ47/36, 44, 29
54
ꢀ32/35, 46, ꢀ35
For N(n2) read S; Ag–S–C(2) is 98.09(4)ꢁ.
b
d Ag(n) is the deviation of the silver atom from ligand plane. +Labelling of the C, H atoms may have more or less digits depending on the
complexity of the structure.
c
The cis-angle in an ÔeclipsedÕ array.
Hpzx =a generic pyrazole), presumably due to breaking
of the B–N bond in the scorpionate ligand and conse-
quent coordination of the azole or of the azolate to
the silver metal center.
and m4 is ca. 80 cmꢀ1, in accordance with a bidentate
nitrato group. This has been confirmed by the presence
of at least two broad bands in the overtones region at
2400–2300 and 1800–1700 cmꢀ1, typical of a bidentate
O2NO group [43].
The infrared spectra of 1–11 (available as Supporting
information) show all the bands required by the pres-
ence of the organic nitrogen donor and of the PiBu3 lig-
and. In all compounds we found the m(CH) of the
heterocyclic ring above 3100 cmꢀ1, the breathing of
In the far-IR spectra of all compounds a number of
weak to medium bands in the region 300–100 cmꢀ1, ab-
sent in the spectra of the alkali metal scorpionate salt
and of [Ag(NO3)(PiBu3)2], can be assigned to Ag–N
and Ag–P vibrations in accordance with previous
assignments. As expected in the far-IR spectrum of 9
we have found several bands due to m(C–S) coupled with
m(Ag–S) bands at ca. 280 cmꢀ1, which suggest ligand thi-
one S-donation [26].
the heterocyclic rings in the range 1600–1500 cmꢀ1
,
and finally the B–N stretching vibration as a band of
medium intensity at ca. 1400 cmꢀ1. In the Tp deriva-
*
tive 7 the B–H stretching appears as a single peak at
ca. 2500 cmꢀ1, suggesting symmetric j3-hapticity [42]
of the ligand (Fig. 2), whereas a closer examination of
the spectra of 3 and 6 reveals a medium absorption at
ca. 2450 cmꢀ1 and the presence of other weaker absorp-
tions at ca. 2400 cmꢀ1, in keeping with the existence of
independent molecules in the solid state, perhaps also
containing the scorpionate ligand in a less symmetric
tripodal chelating fashion (see Section 3.2). In the spec-
trum of [Ag(NO3)(PiBu3)2] the separation between m1
1
In the H NMR spectra of all compounds, recorded
in CDCl3 (see Section 2), the signals due to the tris-
(iso-butyl)phosphine lie in the range 1.0–1.1 (multiplet
due to the methyl), 1.7–2.0 (multiplet due to CH2),
2.1–2.2 (multiplet due to CH), showing a pattern of sig-
nals and chemical shifts different from those found for
free PiBu3 and for [Ag(NO3)(PiBu3)2], and suggesting
the existence of the complexes in solution.

Effendy et al. / Inorganica Chimica Acta 357 (2004) 4247–4256
4253
Fig. 1. Projections, normal to the (quasi-) 3 axes of 3, 4, 5 (three molecules), 8, 9.
1
The room temperature H NMR spectra of the Tpx,
H2B(tz)2, HB(tz)3, HB(btz)2 and Tm exhibit similar sig-
nals for their azolyl groups also at low temperature, sug-
gesting highly fluxional species with either a rocking
or complete dissociation and reassociation of the azolyl
nitrogens or sulfurs occurring rapidly at lower tempera-
ture; in fact, on cooling the CDCl3 solutions to 193 K, no
additional signals due to azolyl protons appeared [44].
The pz0TpMe derivative 11 shows a different behav-
ior: at room temperature only one set of signals is found
+
motion of the Ag(PiBu3)2 moieties between the two or
three nitrogen or sulfur atoms of the scorpionate ligands,

4254
Effendy et al. / Inorganica Chimica Acta 357 (2004) 4247–4256
The coupling constant values of 1–11 well fit into the
correlation previously reported between 1J(109Ag–31P)
N
N
1
and J(107Ag–31P) and the inverse of the cone angle of
H B
Ag
N
N
the phosphorous donor [26]. The values are not strongly
dependent on the steric hindrance of the substituents on
the scorpionate ligands, but are dependent on their elec-
tronic features, the highest values being found for the
N
N
Fig. 2. Symmetric j3-hapticity of Tp in derivative 3.
derivative containing the fluorinated ligand TpCF3
.
We also tested the reactivity of compound
for the protons of the four pyrazolyl groups, whereas
from ca. 203 K each resonance type splits into three with
2/1/1 integrated intensity, indicating that these species
are fluxional at room temperature, but not below 203
K. At this temperature two of the four pyrazolyl groups
appear to be coordinated to silver in an N2AgP trigonal
environment (Fig. 3). In the case of the pzTp derivative
10 at 183 K very broad signals only were detected sug-
gesting that fluxionality is almost lost at this tempera-
ture. The difference between 10 and 11 may be
ascribed to the steric hindrance of the methyl groups
in the pz0TpMe derivative 11.
[Ag{Tp }(PiBu )] (7) toward PPh , monitoring the reac-
*
3
3
tion both by H and 31P NMR. When equimolar quan-
tities of 7 and PPh3 were mixed in CDCl3, a mixture
1
containing equimolar quantities of [Ag{Tp }(PiBu )]
and [Ag{Tp }(PPh )] formed in accordance with com-
*
3
*
3
plete redistribution of the TpAg moiety between the
two P-donors. Interestingly, a large excess of PPh3 reacts
with
7
completely displacing PiBu3 and yielding
[Ag{Tp }(PPh )] in quantitative yield. The full displace-
*
ment reaction does not take place when
3
[Ag{Tp }(PPh )] reacts with excess of PiBu3,
[Ag{Tp }(PPh )] being the most abundant species iso-
*
3
The 31P NMR data for all compounds (chemical
shifts, 109Ag–31P and 107Ag–31P coupling constants) in
CDCl3 solution have been reported in Section 2.
*
3
lated. Interestingly the reaction of [Ag{Tp }(PiBu )]
*
3
with P(o-tolyl)3 does not take place either when a large
excess of P(o-tolyl)3 is employed.
It should be noted that the free phosphine signal (ca.
ꢀ43 ppm) appears upfield of the silver(I) complexes.
Dd(31P)=d(31Pcomplex)ꢀd(31Pligand), the differences in
shift between PiBu3 and the silver complexes lie in the
range 20–35 ppm. It is further worth noting that the
shift is a function of the steric hindrance on the scorp-
ionate ligands, the lower Dd(31P) values being found
The positive electrospray mass spectra of complexes
1–11 (the most relevant data are reported in Section 2)
indicate that these derivatives generally undergo loss
of the anionic scorpionate ligand, the [Ag(PiBu3)x]+ spe-
cies being easily detected. The isotopic distribution of
these species is in accord with the calculated composi-
tion. Some dimeric [Ag2(PiBu3)2(scorpionate)]+ species
have been found in certain cases, their detection presum-
ably being due to the different solubilities of the com-
plexes in acetonitrile solution. The spectra are
independent of the solvent employed, no adducts con-
taining CH3CN being detected at concentration 10ꢀ4 M.
Under our conditions in the solution containing Tp
for the TpMe, Tp and pz0TpMe complexes. The
*
Dd(31P) is greater not only with respect to the values ob-
served in the copper(I) complexes containing scorpion-
ate and monodentate P-donor ligands [25,31,40], in
which a weak bonding interaction has been hypothe-
sized in solution, but is also greater with respect to those
reported for other silver(I) phosphino species [26–30,32].
In contrast to previous observations all scorpionate
compounds and [Ag(NO3)(PiBu3)2] exhibit at room tem-
perature two doublets in which the separate coupling of
31P to the 107Ag and 109Ag are resolved, in accordance
with a stopped or slow phosphine exchange process.
The 1J(109Ag–31P) and 1J(107Ag–31P) coupling constants
for [Ag(NO3)(PiBu3)2] are smaller than those found for
the monophosphine scorpionate complexes, as expected,
and of the same order of magnitude of those reported
for analogous silver(I) phosphino species [45,46].
and Tp , TpMe and TpCF3 complexes, aggregates con-
*
taining two silver atoms, two phosphines and one Tpx
dominate or are equivalent with adducts containing
one silver atom and two phosphine donors, whereas
all other ligands (Tm, pz0Tpx) in solution seem to favor
aggregates containing only one silver center coordinated
by two phosphine donors. In some cases oxidation of
the phosphine is also evident. 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 [NO3]ꢀ, [Ag(NO3)2]ꢀ, and [Ag(NO2)(NO3)]ꢀ [47].
N
N
N
N
N
N
N
N
3.2. Single crystal X-ray studies
B
P
Ag
The results of the single crystal X-ray studies are
consistent with the formulations of 3, 4, 5, 8 in terms
of stoichiometry and connectivity as neutral molecular
1:1 silver(I) tris(azolyl)borate:tris(i-butyl)phosphine
Fig. 3. The N2AgP trigonal environment of compound 11.

Effendy et al. / Inorganica Chimica Acta 357 (2004) 4247–4256
4255
complexes, the silver in each case having a four-coordi-
3.3. Conclusions
nate PAgN3 environment, the tris(azolyl)borate behav-
ing as an N,N0,N00-tripod ligand through the three
2-nitrogen atoms of the three rings; in the case of 9, a
similar array is found except that the three nitrogen
atoms are supplanted by the three sulfur atoms at the
2-ring sites. In 8 and 9, the molecules lie disposed with
their Ag–P bonds lying on crystallographic 3-axes, one
third of the molecule comprising the asymmetric unit of
the structure in each case. In 3 and 4, one, and in 5,
three, complete molecules, devoid of crystallographic
symmetry comprise the asymmetric unit. In all com-
pounds the silver tris(azolyl)borate component has
potential 3m symmetry, realized crystallographically in
none, the rings canted to a greater or lesser degree from
the incipient plane, the distortions evidenced also in the
deviations of the silver atoms from each plane. In 9,
where the donor capability of the sulfur has no copla-
nar imperative, the deviation is very large and the twist
of the ligand plane away from the 3m ideal very consid-
erable. With the phosphine ligand constant, Ag–P are
rather variable, unsurprisingly so in the case of the
New silver tris(iso-butyl)phosphine derivatives con-
taining different bis-, tris- and tetrakis-azolylborates
(L) and also the S3-donor ligand tris(imidazolyl-2-thi-
one)borate Tm have been synthesized and fully charac-
terized in the solid state and solution. The silver/
phosphine/scorpionate ratio is always 1:1:1, even with
the N2-donor H2B(tz)2, where silver atom is likely 3-co-
ordinate. In all complexes containing the N3- and S3-do-
nor ligands the silver atom is four-coordinated in a
skewed tetrahedral coordination environment, whereas
in the complex containing the pz0TpMe ligand, the silver
is 3-coordinated, at least in solution, as indicated by
NMR data. Most of the silver derivatives are quite
light-sensitive and decompose both in chloroform and
acetone solution, yielding metallic silver and/or azolate
species. ESI-MS data indicate the formation in solution
of species as [Ag(PiBu3)2]+ and [Ag2(L)(PiBu3)2]+,
which likely represent intermediates in the decomposi-
tion pattern.
˚
PAgS3 array of 9, where Ag–P is longest, 2.4035(6) A.
Ag–N in those species devoid of crystallographic sym-
metry, are much more variable, with concomitant vari-
ations within ÔequivalentÕ P, N–Ag–N sets. (Æ)N–B–N(æ)
ranges from 109.0(2)ꢁ in 8 to 112.6(1)ꢁ in 9. Considera-
tion of the C–P–Ag–N(S) torsions shows the immediate
phosphorus substituents to be more nearly ÔtransÕ-/stag-
gered to a similar degree in all cases except 8 where they
are ÔcisÕ-/eclipsed. The PiBu3 array forms an ÔumbrellaÕ
at that end of the molecule, jAg–P–C((ln)1)–C((ln)2)j
all being acute, range 28.5(2)–57(1)ꢁ. The subsequent
P–C–C–H torsion in each string is also acute, but,
depending on whether its sign is the same as or the
opposite of, its associated Ag–P–C–C precursor, the
tertiary hydrogen lies directed approximately parallel
to the Ag–P axis and ÔinwardÕ and ÔaxialÕ toward the
other ligand, or ÔequatorialÕ with the three hydrogens
presumably (see 5 below) concerted in direction in ac-
cord with quasi-3 symmetry. The former is found in 3
(two groups), 8 and 9, in situations where the azolyl
rings have no 3 substituent (8) (there are no close inter-
ligand Hꢂ ꢂ ꢂN contacts here which suggest themselves as
drivers of the ÔeclipsedÕ conformation) or where it is re-
moved from the inner ambience by insertion of the sul-
fur (9). The other form (ÔequatorialÕ) is found in 4 and
5, where CH3 or CF3 substituents are found at the 3-
positions of the aza rings, presumably exercising some
interligand steric effect, also in one of the substituents
in 3. 5 is complicated by disorder in some i-butyl sub-
stituents and CF3 groups, most notably in molecule 1
where all i-butyl groups are disordered (presumably in
concert) as if by inversion at the tertiary carbon. Anom-
alously in molecule 3, one of the tertiary hydrogens is
ÔaxialÕ.
Acknowledgements
We thank University of Camerino (Progetto di Ric-
erca Strategico di Ateneo) and CARIMA Foundation
for financial help.
Appendix A. Supporting materials
Selected IR data for all compounds 1–11. Five X-ray
crystallographic files, in CIF format. full cif. depositions
reside also with the Cambridge Crystallographic Data
Centre, #236319-236323. Supplementary data associ-
ated with this article can be found, in the online version
at 10.1016/j.ica.2004.06.020.
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