Synthesis, characterization, crystal structure and luminescence properties of phosphinic silver(I) complexes with thiourea derivatives

Article abstract of DOI:10.1016/j.ica.2007.03.025

Reaction of phenylisothiocyanate with different aromatic amines allowed the synthesis of compounds containing the thiourea moiety. By reacting silver bis(triphenylphosphine)nitrate with suitable ligands belonging to this family of sulphurated compounds, t

Full text of DOI:10.1016/j.ica.2007.03.025

Inorganica Chimica Acta 360 (2007) 3233–3240
www.elsevier.com/locate/ica
Synthesis, characterization, crystal structure
and luminescence properties of phosphinic silver(I) complexes with
thiourea derivatives
*
Marisa Belicchi Ferrari, Franco Bisceglie, Enrico Cavalli, Giorgio Pelosi ,
Pieralberto Tarasconi, Vincenzo Verdolino
`
Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Viale G.P. Usberti 17/a, Universita di Parma, 43100 Parma, Italy
Received 26 September 2006; received in revised form 25 January 2007; accepted 18 March 2007
Available online 23 March 2007
Abstract
Reaction of phenylisothiocyanate with different aromatic amines allowed the synthesis of compounds containing the thiourea moiety.
By reacting silver bis(triphenylphosphine)nitrate with suitable ligands belonging to this family of sulphurated compounds, three new
complexes have been afforded. Ligands and complexes were characterized also by X-ray diffraction. The structures reveal remarkable
differences in the silver coordination geometry in function of the nature and size of the ligand. The emission properties of all compounds
were characterized at 10 and at 298 K.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Thioureic ligands; Silver; Structure elucidation; Luminescence
1. Introduction
tronic and sterical factors peculiar to the ligands. The
structural characterization of these compounds is of
extreme importance in order to shed light on the factors
that influence the reaction mechanism and to gain control
over the synthesis towards the formation of complexes
with predictable geometric requirements. Moreover, it
constitutes the starting point for reliable quantomechani-
cal calculations on these systems.
We have recently undertaken a work about this subject
by reacting [(PPh3)2AgNO3] with thiourea derivatives hav-
ing different geometrical and electronic peculiarities.
In this paper, we report the synthesis and the character-
ization of derivatives of [(PPh3)2AgNO3] with ligands
obtained by condensation of phenylisothiocyanate with 2-
aminopyridine, 2-aminomethylpyridine and 2-aminofluo-
rene, namely 1-phenyl-3-(2-pyridyl)-2-thiourea (Phpytu,
1), 1-phenyl-3-(2-methylpyridyl)-2-thiourea (Phmepytu, 2)
and 1-phenyl-3-(2-fluorenyl)-2-thiourea (Phflotu, 3),
respectively.
The reaction of inorganic silver(I) salts with ternary
organophosphorus derivatives leads to the formation of
different adducts where the metal–ligand ratio varies from
one to four depending on the nature of the ligand, the
stoichiometric ratio between the reagents and the experi-
mental conditions [1]. These compounds can be usefully
employed as precursors of d10 metal complexes with
mixed ligands having different stoichiometries and geome-
tries. These complexes often show interesting lumines-
cence properties involving charge transfer excited states,
whose nature can be assessed only on the basis of reliable
calculations [2]. The coordination chemistry of the d10
metal centres varies markedly as a function of the elec-
*
Corresponding author.
E-mail address: giorgio@unipr.it (G. Pelosi).
0020-1693/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.03.025

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M. Belicchi Ferrari et al. / Inorganica Chimica Acta 360 (2007) 3233–3240
2. Results and discussion
2.1. General
C9
The vibrational spectra of the synthesized compounds
have been recorded and some selected bands are summa-
rized and assigned in the experimental section. Based on
the spectral comparison, the shifts of the mCS and mCN
bands are indicative of metal–ligand interactions. In partic-
ular, the bands assigned to the C@S stretching in the com-
plexes are shifted to lower energies and are less intense if
compared with the corresponding bands of the free ligands.
This behaviour shows a coordination mode via sulphur
atom for all complexes. For complex 5 also the downward
shift observed for the pyridine carbon–nitrogen stretching
shows an S, N coordination. On the contrary, the stretch-
ing assignments of the covalently linked NO3 group in
complex 4 are not so obvious because signals are over-
lapped with other stretching modes of thioureic absorp-
tions [3]. For the other complexes the bands centred at
about 824 cmꢀ1 can be reasonably attributed to the ionic
C10
C11
C8
C7
P1
Ag1
S1
C12
P2
N2
C1
N1
O1
N3
C2
C3
C6
N4
C4
O3
O2
C5
Fig. 1. ORTEP drawing of complex 4 (thermal ellipsoids are drawn at the
50% probability level).
2.2. Crystal structure
ꢀ
NO3 group.
It can be concluded that in general the differences
between the molecular structures found for Ag(I) com-
plexes with the three thioureic derivatives are determined
by topological and rigidity constraints of the used ligands.
The structure of compound 4 consists of neutral com-
plexes represented in Fig. 1. The silver atom presents a
distorted tetrahedral geometry involving two triphenyl-
phosphine phosphorus atoms, a sulphur of the ligand
Table 1
˚
Selected bond distances (A) and angles (ꢁ) for compounds 1, 2 and 4–6
1
2
4
5
6
S1–C1
N1–C1
N1–C2
N2–C1
N2–C7
N3–C2
N3–C6
C2–C3
C3–C4
C4–C5
C5–C6
1.682(2)
1.369(3)
1.398(3)
1.333(3)
1.424(3)
1.328(3)
1.346(3)
1.392(3)
1.374(3)
1.371(4)
1.366(4)
S1–C1
N1–C1
N1–C2
N2–C1
N2–C8
N3–C3
N3–C7
C2–C3
C3–C4
C4–C5
C5–C6
C6–C7
1.683(3)
1.334(3)
1.454(4)
1.343(4)
1.426(4)
1.336(4)
1.337(6)
1.503(6)
1.367(5)
1.379(6)
1.353(5)
1.362(6)
Ag1–S1
Ag1–P1
Ag1–P2
Ag1–O1
S1–C1
N1–C1
N1–C2
N2–C1
N2–C7
2.550(2)
2.479(2)
2.439(2)
2.408(4)
1.694(4)
1.350(7)
1.395(6)
1.311(5)
1.414(7)
Ag1–S1
Ag1–P1
Ag1–P2
Ag1–N3
S1–C1
N1–C1
N1–C2
N2–C1
N2–C8
N3–C3
C2–C3
2.5992(4)
2.4685(5)
2.4867(8)
2.4755(3)
1.693(3)
1.335(2)
1.455(3)
1.348(3)
1.441(2)
1.334(5)
1.511(2)
Ag1–S1
Ag1–P1
Ag1–P2
S1–C1
N1–C1
N1–C2
N2–C1
2.529(1)
2.478(1)
2.483(1)
1.700(3)
1.352(4)
1.434(4)
1.338(4)
S1–Ag1–P1
S1–Ag1–P2
P1–Ag1–P2
Ag1–S1–C1
114.38(4)
114.38(4)
125.40(4)
107.9(1)
S1–Ag1–P1
S1–Ag1–P2
S1–Ag1–O1
P1–Ag1–P2
P1–Ag1–O1
P2–Ag1–O1
Ag1–S1–C1
Ag1–O1–N4
104.07(5)
119.35(5)
98.9(1)
124.64(5)
102.6(1)
102.7(1)
106.9(2)
122.2(4)
C1–N1–C2
C1–N2–C7
C2–N3–C6
S1–C1–N1
S1–C1–N2
N1–C1–N2
N1–C2–N3
N1–C2–C3
N3–C2–C3
C2–C3–C4
C3–C4–C5
C4–C5–C6
N3–C6–C5
N2–C7–C8
N2–C7–C12
130.14(18)
125.96(18)
117.5(2)
118.79(15)
124.42(17)
116.78(18)
118.7(2)
118.61(19)
122.7(2)
118.1(2)
120.0(3)
118.1(3)
123.6(2)
118.91(18)
121.23(19)
S1–Ag1–P1
S1–Ag1–P2
S1–Ag1–N3
P1–Ag1–P2
P1–Ag1–N3
P2–Ag1–N3
Ag1–S1–C1
Ag1–N3–C3
Ag1–N3–C7
111.55(1)
C1–N1–C2
C1–N2–C8
C3–N3–C7
S1–C1–N1
S1–C1–N2
N1–C1–N2
N1–C2–C3
N3–C3–C2
N3–C3–C4
C2–C3–C4
C3–C4–C5
C4–C5–C6
C5–C6–C7
N3–C7–C6
N2–C8–C9
N2–C8–C13
122.1(3)
106.61(1)
101.54(8)
124.25(1)
109.55(7)
100.61(8)
104.0(1)
118.7(3)
118.7(3)
127.0(3)
116.7(3)
122.9(2)
119.9(2)
117.2(3)
113.7(3)
117.0(3)
122.4(3)
120.6(3)
119.0(4)
119.6(4)
117.8(4)
124.5(4)
118.3(3)
121.9(3)

M. Belicchi Ferrari et al. / Inorganica Chimica Acta 360 (2007) 3233–3240
3235
and a nitrate oxygen atom. Selected bond distances and
angles are reported in Table 1. The P1–Ag–P2 angle of
124.64(5)ꢁ approaches very closely the average value found
in similar compounds containing a silver(I) bound to two
triphenylphosphines [1a,4–6] but much smaller than the
value found in the starting nitrate salt [139.4ꢁ] [7]. Conse-
quently, the opposite angle O1–Ag–S1 deviates from the
ideal angle for a tetrahedron presenting a value of
98.90(13)ꢁ. The Ag–P bond distances agree well with the
values found for complexes where the silver atom is tetra-
hedrally coordinated to two phosphorus atoms [4–7]. The
Ag–S bond distance agrees with the mean value found in
analogous compounds [8]. The structure of coordinate
monodentate ligand 1 can be described as built up from
three parts: the phenyl ring, the thiourea fragment and
the pyridine ring. The single units are planar and the pyri-
dine ring is almost coplanar with the thiourea fragment
[8.2(2)ꢁ] thanks to a strong hydrogen bond between the
pyridine nitrogen and a protonated thiourea NH group
(Fig. 3). In this fashion the tetrahedral silver coordination
geometry becomes more regular and the S–Ag–N3 is
101.54(8)ꢁ and the P1–Ag–P2 124.25(1)ꢁ (Table 1). The
ligand molecule is considerably distorted from planarity
and the three components (phenyl ring, thiourea and pyr-
idyl ring) form among them angles of 60.7(2)ꢁ and
73.8(1)ꢁ, respectively, owing to the insertion of a methylene
group that prevents the formation of the intramolecular
N2–H2ꢁ ꢁ ꢁN3 bond determining the conformation in the
free ligand 1 and in its complex 4. The nitrate ion is bound
to the complex through two hydrogen bonds between the
two thiourea NH and two oxygens of the inorganic anion
˚
[N2ꢁ ꢁ ꢁO2 (2 ꢀ x,1 ꢀ y,2 ꢀ z) = 2.792(6) A, N2–Hꢁ ꢁ ꢁO2 =
˚
147(3)ꢁ and N1ꢁ ꢁ ꢁO3 (2 ꢀ x,1 ꢀ y,2 ꢀ z) = 3.029(5) A,
N1–Hꢁ ꢁ ꢁO3 = 156(3)ꢁ].
The geometry of the free ligand Phmepytu 2 (Fig. 4) dif-
fers considerably from that of ligand 1. The presence of the
methylene group between the phenyl ring and the pyridyl
thiourea moiety determines a relevant distortion as
observed also when the ligand is coordinated via N,S in
complex 5. The dihedral angle formed by the phenyl and
thiourea planes is 65.3(1)ꢁ and that between thiourea and
pyridyl ring 83.7(1)ꢁ. As in free ligand 1 the packing is
characterized by dimers formed by N–Hꢁ ꢁ ꢁS hydrogen
˚
[N2ꢁ ꢁ ꢁN3 = 2.675(7) A]. The phenyl, on the contrary,
forms an angle of 71.2(2)ꢁ with the thiourea moiety for
sterical reasons. The nitrate anion behaves as monodentate
and its orientation is affected by a bifurcated hydrogen
bond between the thiourea nitrogen N1 and two of the
˚
nitrate ion oxygens (O1 and O2) [N1ꢁ ꢁ ꢁO1 = 3.068(6) A,
˚
N1–Hꢁ ꢁ ꢁO1 = 143(4)ꢁ and N1ꢁ ꢁ ꢁO2 = 2.955(8) A, N1–
Hꢁ ꢁ ꢁO2 = 153(4)ꢁ].
C13
C12
In the corresponding free ligand 1 (Fig. 2) the conforma-
tion is the same, determined by the strong intramolecular
C8
C2
C1
C4
˚
N2
C9
hydrogen bond [N2ꢁ ꢁ ꢁN3 = 2.642(3) A]. Also in this case
O2
C11
C10
C5
N1
S1
the single units are planar, the pyridine ring and the thio-
urea moiety are almost coplanar [5.4(1)ꢁ] while the phenyl
ring forms an angle of 57.9(1)ꢁ with the thiourea moiety.
The packing is characterized by dimers formed by N–
N4
C3
N3
C6
C7
O3
Ag1
O1
Hꢁ ꢁ ꢁS hydrogen bonds across a centre of symmetry
P2
P1
˚
[N1ꢁ ꢁ ꢁS1(1 ꢀ x,ꢀy,ꢀz) = 3.415(2) A,
N1–H1ꢁ ꢁ ꢁS1 =
166.7(1)ꢁ] and these dimers are packed by van der Waals
interactions.
In complex 5 [Ag(Phmepytu)(PPh3)2]NO3 the organic
ligand replaces completely the nitrate anion showing a
bidentate N,S behaviour and the methylene spacer allows
the formation of
a
seven-membered chelation ring
Fig. 3. ORTEP drawing of complex 5 (thermal ellipsoids are drawn at the
50% probability level).
C6
C9
S1
N3
C6
C8
C9
N3
C5
N2
C10
C7
C10
C1
C7
N2
C5
N1
C8
C13
C4
C11
C12
C4
C1
N1
C3
C11
C2
C3
C2
C12
S1
Fig. 2. ORTEP drawing of ligand 1 (thermal ellipsoids are drawn at the
Fig. 4. ORTEP drawing of ligand 2 (thermal ellipsoids are drawn at the
50% probability level).
50% probability level).

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M. Belicchi Ferrari et al. / Inorganica Chimica Acta 360 (2007) 3233–3240
˚
bonds [N1ꢁ ꢁ ꢁS1(1/2 ꢀ x,3/2 ꢀ y,ꢀz) = 3.376(3) A, N1–
H1ꢁ ꢁ ꢁS1 168(3)ꢁ] and these dimers are packed by van der
Waals interactions.
adducts of the Ag(I)-triphenylphosphine. New attractive
luminescent compounds have been recently synthesized
and their optical spectra have been measured and discussed
on the basis of quantum-mechanical calculations [2]. We
have measured the 10 (LT) and 298 K (RT) luminescence
spectra of the synthesized ligands and complexes in the
solid state. At RT the emission intensities are very low
and often negligible, so we have concentrated our attention
exclusively on the LT spectra. These are shown in Fig. 6.
The spectrum of ligand 1 consists of a broadband with
maximum at about 460 nm and a complex vibronic struc-
ture involving low energy (lattice) phonons. The spectrum
of complex 4 is 20 nm shifted towards the lower energies
and does not present vibronic structure. It has to be
pointed out that the spectrum of pure triphenylphosphine,
reported in Ref. [1a], consists of a broadband peaking at
447 nm. The comparison between these spectra indicates
that the emission properties cannot be preferentially
ascribed to a particular fragment of the complex, but
involve the whole molecule. The same holds for ligand 2
and complex 5, whose spectra are nearly superimposed
with maxima at about 480 and 490 nm, respectively, and
both present some weak vibrational structure. The spectra
of ligand 3 and complex 6 still overlap on to another (max-
ima at about 500 nm), but in this case they show a vibra-
tional progression involving phonons of the order of
700 cmꢀ1, which have correspondence in the IR spectra
of both Ag(I)-triphenylphosphine and ligand (dC–HAr, see
Section 4.2.3). From these considerations, it is evident that
the definition of the states responsible of the luminescence
properties is a difficult task. TD–DFT calculations are in
progress in order to obtain information about the compo-
Introducing the bulky and rigid ligand Phflotu (3) in the
coordination sphere of silver(I) a dramatic change takes
place: its coordination geometry becomes planar trigonal
with angles of 125.40(4)ꢁ, 114.38(4)ꢁ and 114.38(4)ꢁ for
P1–Ag–P2, P1–Ag–S and P2–Ag–S, respectively [9]. The
P1–Ag–S and P2–Ag–S angles are identical, but the
P2SAg unit is not perfectly planar (sum of angles at
Ag = 354.16(5)ꢁ) probably because of a p interaction
between the Ag atom and the aromatic bond C8–C9 of flu-
˚
orenyl moiety (the distance Ag–C1M is 3.11(2) A, where
C1M is the mean point of C8–C9 bond). The angle between
the Ag–C1M line and the normal to the coordination mean
plane is 32.1(2)ꢁ. The formula of complex is [Ag(Phflo-
tu)(PPh3)2]NO3(6) (Fig. 5). The organic ligand, monoden-
tate, shows a remarkable distortion from planarity; in
fact the dihedral angles between the thiourea and phenyl
ring, phenyl and fluorenyl moiety are 50.5(1)ꢁ and
ꢀ
25.0(2)ꢁ, respectively. Also in this case the NO3 ion is
bound through two hydrogen bonds to the two NH of
˚
the thiourea fragment [N1ꢁ ꢁ ꢁO3(ꢀx,ꢀy,ꢀz) = 2.846(5) A,
N1–Hꢁ ꢁ ꢁO3
156.0(2)ꢁ
and
N2ꢁ ꢁ ꢁO1(ꢀx,ꢀy,ꢀz) =
˚
2.782(5) A, N2–Hꢁ ꢁ ꢁO1 170.3(2)ꢁ].
2.3. Emission spectra
A number of Cu(I)- and Au(I)-triphenylphosphine com-
plexes with organic molecules have been extensively inves-
tigated in the past for their interesting emission properties
[10]. Presently these studies are being extended to the
O2
N3
O1
O3
P1
C4
C3
S1
Ag1
C10
C15
C9
C16
C5
C6
C1
C14
C8
N1
C11
P2
C2
C12
C7
N2
C17
C13
C19
C18
C20
Fig. 5. ORTEP drawing of complex 6 (thermal ellipsoids are drawn at the 50% probability level, the fluorenyl moiety was drawing in its highest s.o.f.).

M. Belicchi Ferrari et al. / Inorganica Chimica Acta 360 (2007) 3233–3240
3237
Fig. 6. Emission spectra (10 K) of the synthesized ligands and complexes.
sition of the excited states involved in the optical transi-
4.2. Preparation of the ligands
tions. On the basis of preliminary results, these can be
ascribed to a combination of metal to ligand charge trans-
fer and inter ligand charge transfer processes.
The ligands are obtained in good yields by slowly mixing
appropriate amounts of phenylisothiocyanate and amine in
absolute ethanol at reflux temperature.
3. Conclusions
4.2.1. Phpytu (1)
A round-bottom flask was charged with 0.50 g
In this paper, we report the synthesis of three new thi-
oureic ligands and of their complexes with [(PPh3)2-
AgNO3]. All compounds have been characterized by IR
spectroscopy and X-ray diffraction, and their structural
and conformational properties have been thoroughly dis-
cussed in terms of rigidity and steric hindrance of the
ligand units. It is interesting to point out that the coordina-
tion geometry around the silver atom varies from tetrahe-
dral in complexes 4 and 5 to trigonal in 6, owing to the
differences in the ligands flexibility and in the intramolecu-
lar electronic interactions. Both ligands and complexes are
luminescent at low temperature. Their emission spectra evi-
dence a complex structure of the excited states, as con-
firmed by preliminary TD–DFT calculations.
(5.6 mmol) of 2-aminopyridine and 50 mL of absolute eth-
anol. To this solution phenylisothiocyanate (0.51 mL,
4.3 mmol) was added using a graduated syringe and the
resulting mixture was stirred for 2 h under reflux. After
cooling colourless needles were separated from the solution.
Yield 75%. M.p. 161.5 ꢁC. Anal. Calc. for C12H11N3S
(229.29): C, 62.86; H, 4.84; N, 18.32; S, 13.98. Found: C,
62.17; H, 5.01; N, 18.0; S, 14.15%. Selected IR bands:
3218 (mNAH), 3037 (mCAHAr), 1590 (mC@CAr), 1552 (band B
thiourea + mC@Npy), 1427 (band C thiourea), 1268 (mC@S),
772, 743, 692 (dCAHAr) cmꢀ1. Mass spectrum m/z: 229 (M+).
4.2.2. Phmepytu (2)
To 1.16 mL (9.7 mmol) of phenylisothiocyanate, previ-
ously dissolved in 40 mL of absolute ethanol, 1.00 mL
(9.7 mmol) of 2-aminomethylpyridine was slowly added.
The resultant solution was subsequently stirred for two
hours under reflux. After about 1 h a distinct change in col-
our is observed. At first the solution becomes yellowish and
its pH drops, from the original value of 8, to 7 and then the
colour turns deep green with a further pH decrease to 6.
The solution remains green, also after the separation by fil-
tration of a light yellow crystalline precipitate. Yield 65%.
M.p. 114.0 ꢁC. Anal. Calc. for C13H13N3S (243.32): C,
64.17; H, 5.38; N, 17.27; S, 13.18. Found: C, 63.88; H,
5.52; N, 17.22; S, 13.49%. Selected IR bands: 3340 (mNAH),
3170 (mCAHAr), 2930 (mCAH), 1592 (mC@CAr), 1530 (band B
thiourea + mC@Npy), 1436 (band C thiourea), 1186 (mC@S),
761, 691 (dCAHAr) cmꢀ1. Mass spectrum m/z: 243 (M+).
4. Experimental
4.1. Materials and instruments
All manipulations were performed in air using commer-
cial grade solvents. 2-Aminopyridine (Aldrich, 99%), 2-
aminomethylpyridine (Aldrich, 99%), 2-aminofluorene
(Aldrich, 99%), phenylisothiocyanate (Aldrich, 99%), tri-
phenylphosphine (Aldrich, 99%), AgNO3 (Carlo Erba)
were commercially available and used without further
purification.
Elemental analyses (C, H, N, S) were performed with a
Carlo Erba model EA 1108 automatic analyzer. IR spectra
(4000–400 cmꢀ1) for KBr discs were recorded on a Nicolet
5PC FT. Mass spectra were run on a Finnigan 1020 spec-
trometer (CI). Melting points were determined with a Gal-
lenkamp instrument. The emission spectra were measured
by means of a modified SPEX Fluorolog system. The sam-
ples, in form of pellets, were mounted onto the cold finger
of a He closed cycle cryostat (Air Products), and the mea-
surements were carried out at 10 and 298 K.
4.2.3. Phflotu (3)
To a solution of absolute ethanol containing 0.50 g
(2.76 mmol) of 2-aminofluorene was added 0.33 mL
(2.76 mmol) of phenylisothiocyanate. After stirring for
1 h under reflux a white microcrystalline solid separates.

3238
M. Belicchi Ferrari et al. / Inorganica Chimica Acta 360 (2007) 3233–3240
Yield 85%. M.p. 223.0ꢁC. Anal. Calc. for C20H16N2S
(316.43): C, 75.91; H, 5.10; N, 8.85; S, 10.13. Found: C,
75.83; H, 5.06; N, 8.86; S, 10.20%.
Selected IR bands: 3285 (mNAH), 3052 (mCAHAr), 1590
(mC@CAr), 1538 (band B thiourea + mC@Npy), 1396 (band C
4.3.3. [Ag(Phflotu)(PPh3)2]NO3 (6)
At ambient temperature two solutions are prepared, one
made up from 0.09 g (0.28 mmol) of the ligand in 30 mL of
solvent (acetone:acetonitrile 1:1 v/v) and the other from
0.19 g (0.26 mmol) of triphenylphosphinesilver precursor
dissolved in a solvent mixture having the same composition
as the previous one. The two solutions were then mixed
together in a round bottom flask and stirred in the dark
for 2 h. After three days the solution afforded white crystals
suitable for a structure determination by single-crystal X-
ray diffraction. Yield 96%. T dec. 168 ꢁC. Anal. Calc. for
C56H46AgN3O3P2S (1009.87): C, 66.60; H, 4.49; N, 4.16;
S, 3.18. Found: C, 66.97; H, 4.26; N, 4.20; S, 3.06%.
Selected IR bands: 3052 (mCAHAr), 1591(mC@CAr), 1556
(band B thiourea), 1434, 998 (mPACAr), 1385 (mNO3ꢀþ
band C thioureaÞ, 1130 (mC@S), 828 (mNO3ꢀ), 744, 693
thiourea), 1260 (mC@S), 824, 767, 756, 734, 699 (dCAHAr
)
cmꢀ1. Mass spectrum m/z: 316 (M+).
4.3. Preparation of the complexes
Complexes [Ag(Phpytu)(PPh3)2(NO3)] (denoted by 4),
[Ag(Phmepytu)(PPh3)2]NO3 (5), and [Ag(Phflotu)(PPh3)2]-
NO3 (6), were obtained by mixing in the dark at room tem-
perature the silver salt with equimolar or with a small
excess of the corresponding ligand in an acetone/acetoni-
trile = 1/1 (v/v) mixture. Complexes 5 and 6 were also iso-
lated by mixing equimolar amounts of metal salt and the
ligand both dissolved in dichloromethane in the dark at
room temperature. The compounds isolated were white
or lightly coloured.
(dCAHAr) cmꢀ1
.
4.4. X-ray crystallography
Relevant data concerning data collection and details of
structure refinement are summarized in Tables 2a and 2b.
The intensity data for the ligands were collected with Cu
Ka radiation for 1 on an ENRAF-NONIUS CAD4 and
for 2 on a Siemens diffractometers single-crystal computer
controlled by the h–2h technique. All intensity data for
4.3.1. [Ag(Phpytu)(PPh3)2NO3](4)
A solution obtained by dissolving 0.100 g (0.14 mmol)
of Ag(PPh3)2NO3 in 20 mL of a mixture 1:1 (v:v) of ace-
tone–acetonitrile was poured in 20 mL of the same solvent
mixture containing 0.035 g (0.15 mmol) of Phpytu. The
final volume is stirred for 2 h in the dark. After a few days
this solution yielded white microcrystals. Recrystallization
afforded white crystals suitable for single-crystal X-ray dif-
fraction experiments. Yield 90%. M.p. >300.0 ꢁC. Anal.
Calc. for C48H41AgN4O3P2S (923.75): C, 62.41; H, 4.47;
N, 6.06; S, 3.47. Found: C, 62.07; H, 4.46; N, 6.12; S,
3.14%. Selected IR bands: 3050 (mCAHAr), 1600 (mC@CAr),
1540 (band B thiourea + mC@Npy), 1434, 998 (mPACAr),
1385 (mNAO asym. + band C thiourea), 1299 (mNAO sym.),
Table 2a
Crystal data and structure refinements parameters for ligands 1 and 2
Compound
1
2
Formula
C12H11N3S
C13H13N3S
243.32
C2/c
17.488(5)
8.751(2)
16.970(5)
90.0
108.78(1)
90.0
2459(1)
8
512
1.31
2.44
0.71069
Mo Ka
3–30
ꢀ22 < h < 23,
0 < k < 11,
0 < l < 22
0.4 · 0.4 · 0.3
6509
1302
207
0.59 and ꢀ0.32
Molecular weight
Space group
229.29
P21/n
5.872(1)
22.511(6)
8.750(2)
90.0
98.77(1)
90.0
1143.1(4)
4
˚
a (A)
˚
b (A)
1193 (mC@S), 783, 743, 694 (dCAHAr) cmꢀ1
.
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
4.3.2. [Ag(Phmepytu)(PPh3)2]NO3 (5)
In two aliquotes of 20 mL of a mixture acetone–acetoni-
trile 1:1 (v/v) are dissolved separately 0.09 g (0.097 mmol)
of the triphenylphosphinesilver precursor and 0.03 g
(0.12 mmol) of the ligand Phmepytu. The two solutions were
poured into a round-bottom flask and stirring continued for
2 h protected from light. A white powder precipitated and
was then recrystallized in the dark from the same solvent
and after a few days the solution gave pale green prismatic
crystals. The same product was also obtained by reacting
the two reagents in equimolar ratio in 20 mL of dichloro-
methane. From this reaction crystals form directly from
the reaction solution. Yield 92%. M.p. 216.5 ꢁC. Anal. Calc.
for C49H43AgN4O3P2S (937.78): C, 62.76; H, 4.62; N, 5.97; S,
3.41. Found: C, 62.57; H, 4.69; N, 5.83; S, 3.14%. Selected IR
bands: 3052 (mCAHAr), 1590(mC@CAr), 1555 (mC@CAr),
1477 (band B thiourea + mC@Npy), 1434 (mPACAr), 1400
(mNO3ꢀ þ band C thiourea), 1140 (mC@S), 820 (mNO3ꢀ),
3
˚
V (A )
Z
F(000)
Dcalc (Mg/m3)
480
1.33
23.0
l (cmꢀ1
)
˚
k (A)
1.54178
Cu Ka
3–69
ꢀ7 < h < 7,
0 < k < 27,
0 < l < 10
0.7 · 0.6 · 0.4
2356
Radiation
h Range (ꢁ)
Index ranges
Crystal size (mm)
Measured reflection
Observed reflection
Refined parameters
2034
145
Maximumꢀa3nd minimum
0.33 and ꢀ0.36
˚
DF (e A
)
P
P
R = jjFoj ꢀ jFcjj/ jFoj 0.0495
0.0640
0.2140
Rw2
Weighing scheme
0.1462
2
1=½r2ðF 2oÞ þ ð0:0777 ꢂ PÞ 1=½r2ðF 2oÞ
745, 695 (dCAHAr) cmꢀ1
.
2
þ0:41 ꢂ Pꢃ
þð0:1464 ꢂ PÞ ꢃ

M. Belicchi Ferrari et al. / Inorganica Chimica Acta 360 (2007) 3233–3240
3239
Table 2b
Crystal data and structure refinements parameters for complexes 4–6
Complex
4
5
6
Formula
C48H41AgN4O3P2S
923.75
C49H43AgN4O3P2S
937.78
C56H46AgN3O3P2S
1010.87
Molecular weight
Space group
ꢀ
ꢀ
ꢀ
P1
P1
P1
˚
a (A)
13.136(8)
18.398(7)
10.292(6)
102.74(4)
112.11(5)
91.69(4)
2230(2)
2
13.441(3)
16.969(2)
11.017(4)
99.45(1)
96.26(1)
109.85(1)
2294(1)
2
15.296(6)
14.473(5)
11.993(1)
113.40(2)
98.29(2)
90.56(4)
2405(2)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Z
F(000)
948
1.38
6.15
964
1.36
5.99
1040
1.40
5.77
Dcalc (Mg/m3)
l (cmꢀ1
)
˚
k (A)
0.71069
Mo Ka
3–28
ꢀ17 < h < 15,
ꢀ24 < k < 20,
0 < l < 13
0.7 · 0.7 · 0.5
10352
0.71069
Mo Ka
3–30
ꢀ18 < h < 18,
ꢀ23 < k < 23,
0 < l < 15
0.7 · 0.6 · 0.5
13360
0.71069
Mo Ka
3–30
ꢀ21 < h < 21,
ꢀ20 < k < 20,
0 < l < 16
0.7 · 0.6 · 0.5
14014
Radiation
h Range (ꢁ)
Index ranges
Crystal size (mm)
Measured reflection
Observed reflection
Refined parameters
4528
557
4465
714
6920
665
ꢀ3
˚
Maximum and minimum DF (e A
)
0.72 and ꢀ0.79
0.35 and ꢀ0.27
1.24 and ꢀ1.05
P
P
R = jjFoj ꢀ jFcjj/ jFoj
0.0524
0.0358
0.0486
Rw2
Weighing scheme
0.1554
1=½r2ðF 2oÞ þ ð0:106 ꢂ PÞ ꢃ
0.0836
1=½r2ðF 2oÞ þ ð0:019 ꢂ PÞ ꢃ
0.1342
1=½r2ðF 2oÞ þ ð0:064 ꢂ PÞ ꢃ
2
2
2
complexes were collected with Mo Ka radiation on differ-
ent single-crystal computer controlled by the h–2h tech-
nique diffractometers: a Siemens AED for complex 4, on
an ENRAF-NONIUS CAD4 for 5 and on a Philips for
6. The structures were solved using direct methods (SIR-92
[11] for ligands 1, 2 and SIR-97 [12] for complexes 4–6).
Refinements were carried out by full-matrix least-squares
cycles SHELXL97 [13] for all compounds. Anisotropic ther-
mal motion was assumed for all non-hydrogen atoms. In
complex 6 the fluorenyl moiety adopted two orientations
which were related by a rotation of 180ꢁ about the external
C8–N2 bond. The refined values of occupation factors were
0.7 and 0.3 for the two orientations, respectively. During
the refinement both the phenyl rings was treated as rigid
body having D6h symmetry. For ligand 1 the hydrogen
atoms were included in the ideal positions and not refined,
for 2 the hydrogen atoms were located on a difference map
and refined in the last cycle. In complex 4 the hydrogen
atoms were partly located on a difference map but not
refined and partly were included in the ideal positions
and allowed to ride on their respective parent carbon
atoms. In complex 5 the hydrogen atoms were located on
a difference map and refined, while in complex 6 all hydro-
gen atoms (except those of the fluorenyl moiety) were
included in the ideal positions and allowed to ride on their
respective parent carbon. Atomic scattering factors were
taken from Ref. [14]. Molecular geometry calculations were
performed using the PARST [15] computer program and the
structure drawings obtained with the ORTEPIII [16] and PLA-
TON [17] programs.
5. Supplementary material
CCDC 615626, 615627, 615628, 615629 and 615630 con-
tain the supplementary crystallographic data for 1 2, 4, 5
and 6. These data can be obtained free of charge via
http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from
the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK, fax: (+44) 1223-336-
033, or e-mail: deposit@ccdc.cam.ac.uk.
Acknowledgement
The authors are grateful to Prof. R. Cammi for his help
in performing the TD–DFT calculations.
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