Heptacoordinated diphenyllead; hexa- and pentacoordinated triphenyllead and tin compounds derived from 5H-benzimidazo[1,2-c]quinazoline-6-thione

Article abstract of DOI:10.1016/j.jorganchem.2008.05.022

Heptacoordinated diphenyllead; hexa- and pentacoordinated triphenyllead and tin compounds derived from 5H-benzimidazo[1,2-c]quinazoline-6-thione are reported. The same molecular structures were found in solution by ¹¹⁹Sn and ²⁰⁷Pb NMR and in the solid state by X-ray diffraction analysis. The ligand was bound through S and N giving a four-membered ring. Due to the tension of the chelate ring in the penta- and hexacoordinated compounds, the nitrogen approaches the metal atom from an oblique direction giving a weak coordination. Hexacoordinated metal atoms were obtained by Lewis bases coordination to the polycyclic tin and lead compounds, which was possible because the M-phenyl groups form a cavity that allows the bases to approach from the opposite direction to the sulfur atom. In some crystals, two molecules formed a cavity where a solvent molecule was included. A heptacoordinated diphenyllead bound to two ligands and having the less common pentagonal bipyramidal geometry and cis-mer configuration with two sulfur atoms lying very close together was obtained.

Full text of DOI:10.1016/j.jorganchem.2008.05.022

Journal of Organometallic Chemistry 693 (2008) 2739–2747
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Journal of Organometallic Chemistry
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Heptacoordinated diphenyllead; hexa- and pentacoordinated triphenyllead and
tin compounds derived from 5H-benzimidazo[1,2-c]quinazoline-6-thione
*
*
Adriana Esparza-Ruiz, Adrián Peña-Hueso, Iris Ramos-García, Angelina Flores-Parra , Rosalinda Contreras
Department of Chemistry, Cinvestav, México, A.P. 14-740, 07000 México D.F., Mexico
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 23 April 2008
Received in revised form 14 May 2008
Accepted 14 May 2008
Available online 22 May 2008
Heptacoordinated diphenyllead; hexa- and pentacoordinated triphenyllead and tin compounds derived
from 5H-benzimidazo[1,2-c]quinazoline-6-thione are reported. The same molecular structures were
found in solution by 119Sn and 207Pb NMR and in the solid state by X-ray diffraction analysis. The ligand
was bound through S and N giving a four-membered ring. Due to the tension of the chelate ring in the
penta- and hexacoordinated compounds, the nitrogen approaches the metal atom from an oblique direc-
tion giving a weak coordination. Hexacoordinated metal atoms were obtained by Lewis bases coordina-
tion to the polycyclic tin and lead compounds, which was possible because the M-phenyl groups form a
cavity that allows the bases to approach from the opposite direction to the sulfur atom. In some crystals,
two molecules formed a cavity where a solvent molecule was included. A heptacoordinated diphenyllead
bound to two ligands and having the less common pentagonal bipyramidal geometry and cis–mer config-
uration with two sulfur atoms lying very close together was obtained.
Keywords:
5H-Benzimidazo[1,2-c]quinazoline-6-
thione
119Sn and 207Pb NMR
Hypervalent phenyl lead and tin
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
metallic coordination modes. It has been proposed that compound
1 is a thiol [1,17].
We are interested in the study of planar polycyclic aromatic
compounds bearing nitrogen and sulfur atoms which could have
relevance as cytotoxic or antitumor agents through DNA intercala-
tion. Derivatives of 5H-benzimidazo[1,2-c]quinazoline-6-thione
(1) are interesting due to their cytotoxic [1], antihelmintic [2], vir-
ucides and neoplasm inhibitors [3] or antibacterial activities [4]. In
addition, heterocyclic compounds having the C@S group have bio-
cidal and antitumoral activities and application in analytical chem-
istry and medicine [5–7].
The lone pairs and labile protons of the nitrogen aromatic het-
erocycles make them suitable ligands for metal atoms. In this con-
text, we have especially focused our studies on their coordination
to metal atoms with environmental and toxicological relevance,
such as tin and lead, which give a rich variety of coordination num-
bers and geometries [8–11]. Lead derivatives are especially inter-
esting because they give more stable compounds with higher
coordination numbers and are the less explored.
2. Results and discussion
2.1. General comments
Herein, we report the syntheses of phenyl tin and phenyl lead
organometallic compounds derived from 5H-benzimidazo[1,2-
c]quinazoline-6-thione (1). Reactions were performed using the
sodium amide (2) of 1 and MPh3Cl (M@Sn and Pb) or PbPh2Cl2 in
THF, Scheme 1.
Structures of the starting heterocycle and the coordination
compounds were analyzed in solution by 1H, 13C, 15N, 119Sn and
207Pb NMR. Unequivocal assignments were performed by 2D
experiments [COSY, HETCOR and COLOC]. Crystalline structures
were studied by X-ray diffraction.
The aromatic tetracycle 1 has, as possible reactive sites, a basic
sp2 nitrogen atom, a thione or a thiol group and a labile N–H pro-
ton that could be located at N1, N16 or at the sulfur atom, giving
three possible tautomers. Therefore, not only the preferred tauto-
mer of 1, but the structure of the tin and lead compounds depends
on the competition between the different reactive sites, Scheme 2.
The 13C NMR spectrum of 1 in DMSO (+28 °C) showed the char-
acteristic thione signal at 169.2 ppm, whereas its 15N spectrum in
DMSO-d6 (+80 °C) presented three signals assigned by comparison
with reported indolizine compounds [19]: two singlets, at
In spite of numerous and diverse syntheses of 1 [1,2,4,12–18],
and that it is a starting material for biologically active compounds
and pharmaceuticals [12,13], neither its X-ray diffraction structure
nor its 13C NMR spectrum have been reported. This information is
important in order to establish its preferred tautomer and possible
* Corresponding authors. Tel.: +55 5061 3720; fax: +55 5061 3389.
E-mail address: aflores@cinvestav.mx (A. Flores-Parra).
À195.6 ppm (N3) and À146.3 ppm (N1) and
a doublet at
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.05.022

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A. Esparza-Ruiz et al. / Journal of Organometallic Chemistry 693 (2008) 2739–2747
N
N
N
11
N
12
N 16
1) NaH, THF
2) MPh3Cl
N
S
Ph
Ph
H
S
M
1
Ph
1) NaH, THF
2) 1/2PbPh2Cl2
3 M = Sn; 4 M = Pb
Ph
B
.
.
Fig. 1. X-ray diffraction structure of compound 1 showing the preferred tautomer
and intramolecular hydrogen bonds.
N
N
Pb
Ph
N
N
N
N
5(DMSO) B: DMSO
5(THF) B: THF
frequencies C2 (
D
d = 3.2 ppm), C10 (
Dd = 2.1 ppm), C11 (Dd =
S
S
8.4 ppm) and C12 (
D
d = 8.6 ppm) which confirmed that N16 was
protonated in compound 1. The 15N spectrum indicated that the
N16 signal was shifted from d = À225.2 ppm in 1 to À158.9 ppm
in 2. The other two signals remained constant (N1 d = À142,7 ppm,
N3 d = À191.1 ppm). Compound 2 was reacted in situ with SnPh3Cl,
PbPh3Cl and Ph2PbCl2.
Scheme 1.
À225.6 ppm for N16–H {1J(15N–1H) = 93.6 Hz}, which clearly
shows that the preferred tautomer in solution has the labile proton
at N16.
2.2. Tin compounds
The solid state structure of 1 was obtained by X-ray diffraction
analyses, one polymorph was crystallized from CHCl3 (1a) and a
second (1b) from acetone or EtOH. Both crystalline structures have
a proton at N16, Fig. 1. It has two intramolecular hydrogen bonds,
one between H4 and sulfur, and the other between N1 and H15,
Fig. 1.
The polymorph 1a (monoclinic, C2/c) forms a polymer orga-
nized in planar ribbons by the presence of cooperative hydrogen
bonds, Fig. 2. The second polymorph 1b (monoclinic, P21/n) pre-
The reaction of 2 with SnPh3Cl in THF afforded a light brown
crystalline powder (3), Scheme 1. The 13C NMR spectra (CDCl3 or
DMSO-d6) showed the C–S single bond character (152.5 ppm)
and the shift of C11 and C12 to higher frequencies showed the
presence of a lone pair at the N16. The 119Sn resonance in CDCl3
or THF appeared at À114.7 ppm, shifted by 50 ppm to lower fre-
quencies when compared with the value for a thiophenolate tin
compound [SnPh3SPh (CDCl3) appears at À64.3 ppm, Table 1].
The tin signal of 3 is similar to that of a 2-thiolpyridine triphenyltin
derivative (d = À116.3 ppm) [20], therefore, it was concluded that
tin was bonded to the sulfur and coordinated by N16. The nitrogen
and sulfur chelate forms a four-membered ring, giving a pentacy-
clic fused system bearing a pentacoordinated tin atom. This type
of chelate has been reported for tin and lead compounds [20–25].
sents two intermolecular hydrogen bonds and
p stacking, Fig. 3.
The sodium amide (2) was obtained by reaction of compound 1
with NaH in THF and directly analyzed by NMR. The 1H NMR spec-
trum did not show the NH proton signal. The electron withdrawing
effect of the N16-lone pair shifted the 13C resonances to higher
H
N
7
14
12
N1
N
N
15
8
6
5
10
13
2
3
N
9
N
S
11
4
17
N
16
N
N
S
H
H
S
Scheme 2. Tautomers of compound 1.
Fig. 2. H-bonds, NÁ Á ÁH–C, C@SÁ Á ÁH–N and C@SÁ Á ÁH–C, in the cell of polymorph 1a crystallized from CHCl3.

A. Esparza-Ruiz et al. / Journal of Organometallic Chemistry 693 (2008) 2739–2747
2741
Fig. 3. Interactions in the net of the polymorph 1b obtained from acetone.
Table 1
radii [27], with the exception of the structure having DMSO (3e),
Fig. 5. In crystals 3e, the oxygen atom of the DMSO is pointing to
the tin within a distance of 3.05(2) Å. Sulfur and oxygen atoms
are in trans position, forming a S–Sn–O angle of 174.6°. Compound
3 in the different crystals 3a–3e with or without solvent has the
same structure with similar angles and bond lengths, Table 2.
The tin geometry in crystals 3a–3e is a distorted tbp, the apical
positions are occupied by a phenyl group and the nitrogen atom
[N16–Sn–C32 angles are in the range of 152.3(2)–159.4(2)°]. The
distance N ? Sn (from 2.82 to 2.88 Å) is shorter than the sum of
119Sn or 207Pb and 13C NMR data of 3–5 and other related compounds
Tin compounds – solvent
SnPh3SPh – CDCl3
SnPh3SPh – THF-d8
SnPh3SPh – DMSO-d6
3 – THF
d
119Sn
À64.3
À66.5
M–Ci 1J(119/117Sn, 13C)
137.6 (561, 536)
137.8 (571, 531)
142.2 (568, 541)
140.0 (606, 579)
140.0 (599, 576)
143.7 (766, 732)
M–Ci, 1J(207Pb,13C)
153.1 (491.1)
153.4 (508.1)
156.1 (not obs.)
156.5 (553.5)
160.3 (754.7)
173.4 (1729.3)
À140.1
À114.7
À114.7
À231.7
3 – CDCl3
3 – DMSO-d6
Lead compounds – solvent
PbPh3SPh – CDCl3
PbPh3SPh – THF-d8
PbPh3SPh – DMSO-d6
4 – CDCl3
d
207Pb
À14
À24
the van der Waals radii
(Rrcov Sn–N = 2.15 Å; RrvdW Sn–
À100
À68
N = 3.85 Å) [27]. Other reported tin compounds bound to thiourea
aromatic molecules form S,N four-membered ring chelates, their
bond lengths Sn–S appear between 2.44 and 2.53 Å and N ? Sn
bonds between 2.43 and 3.16 Å [20,21,24,25]. Crystals 3a–3e are
4 – DMSO-d6
5 – DMSO-d6
À227
À523
stabilized by C–HÁ Á ÁN, C–HÁ Á Á
p hydrogen bonds and p interactions,
Figs. 6 and 7.
The 119Sn spectrum of compound 3 dissolved in DMSO-d6
showed a signal at À231.7 ppm, characteristic of a hexacoordinate
tin atom, Scheme 3, as a result of DMSO coordination [26].
Crystallization of compound 3 from THF/DMSO (10:1) gave
crystals (3a) without solvent in the lattice, Fig. 4. Crystallization
from CDCl3 (3b), THF (3c), acetone (3d) and DMSO (3e) gave iso-
ꢀ
morphous crystals (triclinic P1) which contain a solvent molecule
in the cavity formed by the cones of two SnPh3 groups, Fig. 5.
Crystals 3b–3e contain solvent (disordered) which can appear
in either of two orientations. The distances of the solvent mole-
cules to the tin atoms are longer than the sum of the van der Waals
N
N
N
S
Ph
Ph
Ph
M
O
CD3
S
D3C
Scheme 3. Hexacoordinated compounds (M@Sn) and (M@Pb).
Fig. 4. ORTEP diagram of compound 3a.

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A. Esparza-Ruiz et al. / Journal of Organometallic Chemistry 693 (2008) 2739–2747
Fig. 5. X-ray diffraction of crystalline structure of isomorph 3e.
2.3. Lead compounds
Table 2
Bond lengths (Å) and angles (°) of compound 3 in crystals 3a–3e
Lead(IV) compounds were prepared from PbPh3Cl and Pb Ph2Cl2
and 1 or 2 equiv. of the sodium amide 2 in THF. The reaction prod-
ucts were analyzed by 207Pb NMR. The reaction between amide 2
and PbPh3Cl in equimolar ratio afforded mainly compound 4, and
2% of a compound identified as 5. 13C and 1H NMR analyses of 4
confirmed that it has a similar structure to tin compound 3, with
the lead chelated by sulfur and nitrogen atoms, Scheme 1.
Comparison of 207Pb data and coupling constants 1J(207Pb–13C)
of compound 4 with Ph3PbSPh in different solvents allows evalua-
tion of the N ? Pb coordination bond in compound 4, Table 1. The
strong effect of the DMSO-d6 on the chemical shift of compound 4
(d = À227.0 ppm) shows that the solvent coordination afforded the
hexacoordinated lead compound 4a, Scheme 3.
The reaction of 2 equiv. of ligand 2 and PbPh2Cl2 gave com-
pound 5, Scheme 1. The 207Pb chemical shift of compound
5(DMSO) (d = À523 ppm) in DMSO corresponds to a highly coordi-
nated compound, bound by two ligands and DMSO. The heptacoor-
dinated structure was confirmed later by X-ray diffraction analysis
of the corresponding THF complex 5(THF).
C17
S18
N16
C17
S18
N16
C20
C26
C20
C26
Sn
Sn
C32
O38
3e
C32
3a-3d
Átoms
3a
3b
3c
3d
3e
N16–Sn
S18–Sn
C17–S18
C17–N16
2.819(4)
2.479(2)
1.742(5)
1.290(6)
–
159.4(2)
110.9(1)
114.2(2)
100.9(2)
116.5(2)
107.2(2)
105.5(2)
2.883(3)
2.460(1)
1.743(4)
1.302(4)
4.402(4)
153.7(1)
110.6(1)
113.1(1)
95.50(1)
120.5(2)
106.9(1)
107.1(1)
2.881(3)
2.465(1)
1.746(4)
1.293(4)
3.81(3)
153.7(1)
112.5(1)
110.6(1)
95.8(1)
2.872(3)
2.463(1)
1.746(4)
1.294(5)
4.46(1)
153.6(1)
113.4(1)
111.0(1)
95.5(1)
2.901(4)
2.473(2)
1.747(5)
1.289(7)
3.05(2)
152.3(2)
109.6(2)
111.2(1)
94.7(2)
SnÁ Á ÁCl or O38
N16–Sn–C32
S18–Sn–C20
S18–Sn–C26
S18–Sn–C32
C20–Sn–C26
C26–Sn–C32
C32–Sn–C20
From the reaction product containing the mixture of 4 and 5,
crystals of each compound were obtained and their structures
determined by X-ray diffraction. Compound 4, co-crystallized with
120.8(2)
106.7(1)
107.1(1)
119.8(2)
107.1(2)
106.8(1)
122.3(2)
107.8(2)
107.6(2)
ꢀ
a CHCl3 molecule (triclinic P1), has a similar structure to 3b. It is a
Fig. 6. C–HÁ Á ÁN, C–HÁ Á Á
p H-bonds in 3a.

A. Esparza-Ruiz et al. / Journal of Organometallic Chemistry 693 (2008) 2739–2747
2743
Fig. 7.
p-Interactions and H-bonds in 3b.
pentacoordinated triphenyllead compound with a covalent bond to
sulfur and coordination to the nitrogen atom. Two molecules form
a cavity, where a solvent molecule is found. The lead molecule 4
The S–Pb bonds [2.65 Å (
N16–Pb bonds [2.77 Å (
distortion of the geometry around the lead atom. The sulfur
R
rvdW = 3.80 Å)] are shorter than
R
rvdW = 3.55 Å)]. There is an interesting
forms dimers by
p
-stacking, Fig. 8.
atoms are in cis position, with a short interligand SÁ Á ÁS contact
Compound 5, has a heptacoordinated lead atom, bound to two
ligands (cis–mer isomer) and two phenyl groups. One molecule of
THF was also coordinated to the lead atom (Pb–O26 3.26 Å;
of 3.40 Å, (RrvdW S–S = 3.60 Å), the angle S–Pb–S is very closed
(79.74°) whereas the N–Pb–N is very open (165.47°). The C–Pb–
C bonds have an angle of 145.8° instead of the expected value
of 180°. There is no steric reason for the small S–Pb–S angle
and the short SÁ Á ÁS distance as there is enough room for the
two chelates which would allow the sulfur atoms to separate
themselves, according to VSEPR theory [28]. A coordinated THF
occupies the cavity formed between the two phenyl and two phe-
nylene groups, although this does not appear to be the reason for
the open N–Pb–N angle. There are examples of other diphenyltin
and diphenyllead compounds having two S N four-membered
chelates rings, which have the same distortion with closed S–
R
rvdW = 3.52 Å), Fig. 9.
The lead atom is a distorted pentagonal bipyramid with the
phenyl groups occupying the apical positions and a pentagonal
plane depicted by two sulfurs, two nitrogens and the oxygen of
the THF, Fig. 10. The two ligands are arranged in the equatorial
plane. Selected bond lengths and angles are in Table 3. To our
knowledge, compound 5 is the second example of a heptacoordi-
nated diphenyllead atom having an O ? Pb coordination bond,
the first being reported by Casas et al. [23].
Fig. 8.
p-Stacking in compound 4.

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A. Esparza-Ruiz et al. / Journal of Organometallic Chemistry 693 (2008) 2739–2747
Table 3
Bond lengths (Å) and angles (°) for compound 5(THF)
Ph
O 26
16
11
10
19
N
N
2
Pb
1N
17
N
N
N
18S
S
3
8
20
9
N1–C2
N1–C8
C2–N3
C2–C10
N3–C9
1.304(5)
1.388(7)
1.402(5)
1.433(7)
1.408(5)
1.392(4)
1.391(5)
N16–C17
N16–Pb
C17–S18
S18–Pb
Pb–C20
Pb–O32
1.295(5)
2.765(3)
1.718(4)
2.6500(9)
2.191(4)
3.258(5)
Fig. 9. Solid state structure of compound 5(THF).
N3–C17
C11–N16
C2–N1–C8
N1–C2–N3
N1–C2–C10
N3–C2–C10
C2–N3–C9
C2–N3–C17
C9–N3–C17
C7–C8–N1
N1–C8–C9
N3–C9–C8
N3–C9–C4
N16–C17–S18
C17–S18–Pb
S18–Pb–N16
105.2(4)
112.6(4)
129.9(4)
117.5(3)
106.6(3)
121.4(3)
132.0(3)
128.7(5)
111.9(4)
103.7(4)
133.7(4)
119.2(3)
89.1(1)
C10–C11–N16
C12–C11–N16
C11–N16–C17
C11–N16–Pb
C17–N16–Pb
N3–C17–N16
N3–C17–S18
S18–Pb–C20
N16–Pb–C20
Pb–C20–C21
Pb–C20–C25
O26–Pb–S18
O26–Pb–C20
C20–Pb–C20
121.7(4)
118.7(4)
120.8(3)
145.0(2)
94.1(2)
121.0(3)
119.8(3)
105.6(1)
87.3(1)
119.2(3)
121.0(3)
140.1(1)
72.9(1)
57.54(7)
145.8(1)
Fig. 10. Coordination sphere around the lead atom in 5.
Pb–S and C–Pb–C angles and an open N–Pb–N angle [29–32]. An
example is shown in Fig. 11 [22].
The distortion of compound 5 could be the result of a stabilizing
interaction between the sulfur atoms SÁ Á ÁS, as it has been pointed
out for molybdenum compounds such as in Fig. 12 [33], or the ef-
fect of
p-donor ligands competing for a given set of metal d-orbi-
tals [28].
The THF coordination in compound 5(THF) merits some com-
ments. In addition to the O ? Pb coordination, the THF was also
bound by two hydrogen bonds between the ortho CH protons of
the phenylene groups and the oxygen atom, which becomes penta-
coordinated (O26Á Á ÁH12, 2.55 Å, O26–H12–C12 = 173.2°), Fig. 13.
Each nitrogen atom forms two hydrogen bonds with the ortho C–
H of the Pb-phenyl groups producing a pentacoordinated nitrogen
atom N16Á Á ÁH25 (2.46 Å, N16–H25–C25 = 135.6°), N16Á Á ÁH21
(2.47 Å, N16–H21–C21 = 140.1°). Sulfur atoms also present intra-
molecular H-bonds S18Á Á ÁH4 (2.64 Å, S18–H4–C4 = 122.7°), Fig. 14.
Fig. 11. Distorted geometry in a reported hexacoordinated lead compound [22].
Angles values are N–Pb–N 161.9°, S–Pb–S 83.96° and C–Pb–C 142.8°.
3. Summary
The preferred tautomer of the ligand 5H-benzimidazo[1,2-
c]quinazoline-6-thione 1 and the corresponding phenyl lead and
tin organometallic derivatives were fully characterized in solid
state and in solution. 119Sn and 207Pb NMR gave enough informa-
tion to determine the coordination number of the metal atoms
and the ligand coordination mode in solution. The ligand was
bound through S and N forming four-membered rings. Due to the
tension of the chelate ring, the nitrogen approaches the metal atom
from an oblique direction giving, by a weak coordination, the pen-
ta- or hexacoordination of the metal atom. The polycyclic tin and
Fig. 12. Hexacoordinate dioxomolybdenum(VI) complexes containing a non-octa-
hedral, cis–mer structure presenting a short SÁ Á ÁS contact [33].
lead compounds were coordinated by Lewis bases, which approach
the metal atom from a direction opposed to the S–M bond through
the cavity formed by the M-phenyl groups. In some crystals a

A. Esparza-Ruiz et al. / Journal of Organometallic Chemistry 693 (2008) 2739–2747
2745
were purchased from Aldrich and used without further purifica-
tion, PbPh2Cl2 was synthesized according to the literature [34].
The melting points were obtained on a Mel-Temp II apparatus
and are uncorrected. Mass spectra in the EI mode were recorded
at 20 eV on a Hewlett–Packard HP 5989 spectrometer. High resolu-
tion mass spectra were obtained by LC/MSD TOF on an Agilent
Technologies instrument with APCI as ionization source. Elemental
analyses were performed on Eager 300 equipment. 1H, 13C [
25.145020, Si(CH3)4], 15N 10.136767, CH3NO2], 119Sn
= 37.290 Sn(CH3)4] and 207Pb [ 20 920 597, Pb(CH3)4]. 15N
N
[N
[N
N
spectra were obtained with single pulse experiments, whereas
119Sn and 207Pb were obtained by single pulse with broad decou-
pling experiments. NMR spectra were obtained on a Jeol GSX-
270, Jeol Eclipse 400 MHz and Bruker Advance 300 MHz. IR spectra
were taken in KBr disc using a FT Spectrum GX Perkin–Elmer
spectrometer.
4.2. Syntheses
4.2.1. 5H-benzimidazo[1,2-c]quinazoline-6-thione (1)
2-(1H-benzimidazol-2-yl)-phenylamine (500 mg, 2.39 mmol)
was reacted with KOH (268 mg, 4.78 mmol) in DMF (20 mL). The
solution was stirred for 2 h, then cooled to 0 °C and an excess of
CS2 (11.6 mmol, 0.7 mL) was added and stirred for another 2 h.
The reaction mixture was neutralized with aqueous HCl, filtered
and washed with CHCl3. The product is a light brown powder. Light
brown plates were obtained by recrystallization from CHCl3
(570 mg, 95%). M.p. 284–285 °C. 1H NMR (DMSO-d6), d (ppm):
13.45 (s, N–H), 9.35 (d, 3J 8.3 Hz, H-4), 8.33 (d, 3J 7.9 Hz, H-15),
7.87 (d, 3J 7,9 Hz, H-7), 7.67 (t, 3J 7.9 Hz, H-13), 7.54 (t, 3J 7.9 Hz,
H-6), 7.45 (dd, 3J 7.9, 8.3 Hz, H-5), 7.43 (t, 3J 7.9 Hz, H-14), 6.88
(d, 3J 7.9 Hz, H-12). 13C NMR (DMSO-d6), d (ppm): 169.2 (C17),
145.1 (C2), 144.2 (C8), 135.6 (C11), 132.4 (C13), 132.1 (C9), 125.9
(C6), 125.0 (C14), 124.3 (C15), 123.2 (C5), 119.2 (C7), 116.9 (C4),
115.9 (C12), 113.2 (10). 15N NMR (DMSO-d6), d (ppm): À225.6 (1J
93.6 Hz, N16), À195.6 (N3), À146.3 (N1). EM: m/z (%): 251(100)
[M]+, 219(8.0) [MÀS]+, 207(6.0) [MÀCS]+. Anal. Calc. for
Fig. 13. Solid state structure of compound 5(THF) showing the two hydrogen bonds
to the THF oxygen atom (2.545 Å).
C14H9N3S: C, 66.91; H, 3.61; N, 16.72. Found: C, 66.59; H, 3.66; N,
16.76%. IR (KBr),
m
(cmÀ1): 1633 (C@N), 1326 (C–N), 1176 (C@S),
3464 (N–H). A polymorph of 1 was obtained from recrystallization
in acetone, as light brown plates. M.p. 298 °C. EM: m/z (%):
251(100) [M]+, 219(36) [MÀS]+, 207(28) [MÀCS]+. Anal. Calc. for
C14H9N3S: C, 66.91; H, 3.61; N, 16.72. Found: C, 66.58; H, 3.98; N,
16.52%. IR (KBr),
3454 (N–H).
m
(cmÀ1): 1628 (C@N), 1324 (C–N), 1168 (C@S),
4.2.2. (Benzimidazo[1,2-c]quinazoline-jN)-6-thiolate-jS]triphenyl tin
(3) 1J{119Sn–13C}
Fig. 14. Solid state structure of 5(THF) showing the N16Á Á ÁH25 (2.46 Å, N16–H25–
C25 = 135.6°), N16Á Á ÁH21 (2.47 Å, N16–H21–C21 = 140.1°) and S18Á Á ÁH4 (2.636 Å)
hydrogen bonds.
Compound 1 (86 mg, 34 mmol) was dissolved in THF and
8.2 mg (34 mmol) of NaH was added. The solution was cooled to
À70 °C and (C6H5)3SnCl (132 mg, 34 mmol) was added and the
reaction mixture stirred for 15 h at r.t., then filtered and the solvent
evaporated under vacuum. A light brown powder was obtained
(175 mg, 85%). M.p. 298–300 °C. 1H NMR (CDCl3), d (ppm): 8.86
(d, 3J 8.2 Hz, H-4), 8.63 (d, 3J 7.4 Hz, H-15), 8.02 (d, 3J 8.0 Hz, H-
7), 7.59 (H-6), 7.56 (H-13), 7.52 (H-5), 7.50 (H-14), 7.29 (d, 3J
8.1 Hz, H-12). 13C NMR (CDCl3), d (ppm): 152.5 (C17), 147.7 (C2),
144.3 (C8), 142.2 (C11), 140.0 (1J{119Sn–13C} 606.0 and
1J{117Sn–13C} 579.1 Hz, CI), 136.6 (1J{119Sn–13C} 46.5 Hz, Co), 131.8
(C13), 130.2 (C9), 129.9 (1J{119Sn–13C} 13.1 Hz, Cp), 129.1
(1J{119Sn–13C} 62.0 Hz, Cm), 126.6 (C14), 126.0 (C6), 124.6 (C12),
124.5 (C15), 123.1 (C5), 119.8 (C7), 117.2 (C10), 115.6 (C4). 1H
NMR (DMSO-d6), d (ppm): 9.23 (H-4), 8.35 (H-15), 7.85 (H-7),
7.50 (H-6), 7.62 (H-13), 7.44 (H-5), 7.41 (H-14), 7.48 (H-12). 13C
NMR (DMSO-d6), d (ppm): 159.1 (C17), 147.0 (C2), 143.7 (C8),
141.7 (C11), 143.5 (1J{119Sn–13C} 766.0 and 1J{117Sn–13C}
solvent molecule was included in the cavity formed by two organo-
metallic molecules. A heptacoordinated diphenyl lead compound
having the less common pentagonal bipyramidal geometry was
obtained. The isomer formed is the cis–mer, with the sulfur atoms
lying very close together and stabilized by SÁ Á ÁS interaction.
4. Experimental
4.1. General comments
Vacuum line techniques were employed for all manipulations of
air and moisture sensitive compounds. THF was dried by distilla-
tion from sodium-benzophenone under a nitrogen atmosphere
prior to use. Dry CDCl3, DMSO-d6, THF-d8, SnPh3Cl and PbPh3Cl

2746
A. Esparza-Ruiz et al. / Journal of Organometallic Chemistry 693 (2008) 2739–2747
732.2 Hz, CI), 136.0 (2J{119Sn–13C} 45.5 Hz, Co), 131.5 (C13), 130.7
(C9), 128.9 (Cp), 128.4 (3J{119Sn–13C} 67.7 Hz, Cm), 124.8 (C14),
125.0 (C6), 123.4 (C12), 123.6 (C15), 121.9 (C5), 118.8 (C7), 115.4
All non-hydrogen atoms were refined anisotropically. For 1a–
1b, 3b–3e and 5 all hydrogen atoms were located using a differ-
ence map, except those of the disordered solvent molecules which
were geometrically place. For 1a and 1b only the NH positions
were refined, the rest were included as riding atoms. The position
of the hydrogen atoms in 3a and 3b were refined whereas in 3d, 3e
and 4 the hydrogen atoms were replaced in ideal positions and in-
cluded as riding atoms. In compound 5 only the positions of all aro-
matic hydrogen were refined. Selected bond lengths and angles are
presented in Table 3.
(C10), 116.7 (C4). IR (KBr),
m
(cmÀ1): 1625 (C@N), 1347 (C–N),
697 (C–S). EM: m/z (%): 601(2.9) [M]+, 524(100) [M–C6H5]+,
251(98.7) [M–Sn(C6H5)3]+. Anal. Calc. for C32H23N3SnS: C, 64.03;
H, 3.86; N, 7.00. Exp.: C, 63.86; H, 3.95; N, 6.89%.
4.2.3. (Benzimidazo[1,2-c]quinazoline-jN)-6-thiolate-jS]triphenyl
lead (4)
Compound 1 (400 mg, 1.59 mmol) was dissolved in 30 mL of
THF, 42 mg (1.75 mmol) of NaH were added followed by
(C6H5)3PbCl (754 mg, 1.59 mmol). The reaction mixture was stirred
for 3 days at r.t., then filtered and the solvent evaporated under
vacuum. A light brown powder was obtained (850 mg, 77%). M.p.
290 °C. 1H NMR (CDCl3), d (ppm): 9.01 (H-4), 8.63 (H-15), 8.07
(H-7), 7.55 (H-6), 7.58 (H-13), 7.47 (H-5), 7.50 (H-14), 7.36 (H-
12). 13C NMR (CDCl3), d (ppm): 153.1 (C17), 147.6 (C2), 143.8
(C8), 142.3 (C11), 156.5 (1J{207Pb–13C} 553.5 Hz, CI), 136.5
(1J{207Pb–13C} 84.6 Hz, Co), 131.2 (C13), 130.2 (C9), 129.9
(1J{207Pb–13C} 123.1 Hz, Cm), 129.3 (1J{207Pb–13C} 22.7 Hz, Cp),
125.7 (C14), 125.2 (C6), 124.6 (C12), 124.0 (C15), 122.3 (C5),
119.2 (C7), 116.7 (C10), 115.9 (C4). 1H NMR (DMSO-d6), d (ppm):
9.23 (H-4), 8.35 (H-15), 7.85 (H-7), 7.50 (H-6), 7.62 (H-13), 7.48
(H-12), 7.44 (H-5), 7.41 (H-14). 13C NMR (DMSO-d6), d (ppm):
160.3 (C17), 160.3 (1J{207Pb–13C} 754.7 Hz, CI), 146.9 (C2), 143.7
(C8), 141.3 (C11), 136.2 (1J{207Pb–13C} 83.3 Hz, Co), 131.7 (C13),
130.4 (C9), 129.8 (1J{207Pb–13C} 109.1 Hz, Cm), 129.6
(1J{207Pb–13C} 23.3 Hz, Cp), 125.4 (C6), 125.2 (C14), 123.7 (C15),
122.2 (C12, C5), 119.0 (C7), 116.6 (C4), 115.6 (C10). TOF-MS:
Acknowledgements
Financial support from Conacyt-Mexico and Cinvestav is
acknowledged as well as Conacyt-Mexico scholarships for A.E.-R.
and A. P.-H. The authors are grateful to A. Paz-Sandoval and J.
Guthrie for valuable comments and discussions.
Supplementary material
CCDC 683576, 683577, 683578, 683579, 683580, 683581,
683582, 683583 and 683584 contain the supplementary crystallo-
graphic data for 1a, 1b, 3a, 3b, 3c, 3d, 3e, 4 and 5. These data can be
obtained free of charge from The Cambridge Crystallographic Data
Centre via http://www.ccdc.cam.ac.uk/data_request/cif. Supple-
mentary data associated with this article can be found, in the on-
line version, at doi:10.1016/j.jorganchem.2008.05.022.
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