14
B.A. Iglesias et al. / Journal of Organometallic Chemistry 752 (2014) 12e16
Fig. 3. The molecular structure with the atom-labeling scheme of the [PbII{O2N(C6H4)
NNN(O)Ph}2] with 40% thermal ellipsoids (using DIAMOND software [20]).
squares on F2, with anisotropic displacement parameters for all
non-hydrogen atoms. Hydrogen atoms were included in the
refinement in calculated positions. Drawings were done using
DIAMOND for Windows [20]. Crystal data and more details of the
data collection and refinements are contained in Table 1.
Fig. 2. Section of the extended one-dimensional tecton of the N-oxide ligand with 40%
thermal ellipsoids (using DIAMOND software [20]). Symmetry operations used to
generate equivalent atoms: (#) 1 ꢁ x, ꢁy, ꢁz.
4. Results and discussion
4.1. Crystal structure
The ligand triazene-1-oxide was synthesized from a classical
diazotization reaction [21,22]. The crystal structure of the N-oxide
ligand consists of atoms of an organic molecule with the functional
diazoamino group N11]N12eN13 featuring an asymmetric tri-
azene, the molecule is composed of aromatic rings linked to the
terminal nitrogens (N11 and N13). The ring attached to the terminal
nitrogen N13 has a nitro function (ꢁNO2) and the other ring
attached to the terminal nitrogen N11 is presented only as a phenyl
ring (Fig. 1).
under stirring to a solution of 0.03 g (0.116 mmol) of 1-phenyl-3-
(4-nitrophenyl) triazene 1-oxide in 20 mL of THF. To the dark-
purple solution of the deprotonated ligand, 0.018
g
(0.058 mmol) of Pb(SCN)2 was dissolved in 5 mL of absolute
MeOH. After 1 h, 2 g of anhydrous MgSO4 was added and the
mixture was stirred for an additional 20 min. The mixture was
filtered and the solvent was evaporated. The residual orange
solid was dissolved in an absolute mixture of methanol/pyridine
(10:2 v/v) see Scheme 1. Prismatic light-orange crystals were
obtained within three days after slow evaporation of the solvent
at room temperature. Yield of 60% (0.034 mmol) based on tri-
azene taken.
ꢀ
The length of the N12eN13 bond [1.333(2) A] is less than the
ꢀ
characteristic value for a single NeN bond (1.44 A), while the length
ꢀ
of the N11eN12 bond [1.276(2) A] is larger than the bond length for
ꢀ
a typical C]N double bond (1.24 A). All these afore mentioned
Properties: prismatic light-orange crystalline substance
24H18N8O6Pb (721.65 g molꢁ1) and melting point of 290 ꢀC. IR
(KBr) lead(II) triazenide complex: 1222 [s, (N/O)]; 1107 [s, (Ne
N)]; 1334 [s, (NO2)]; and 1311 [vs, (NNN)] e the (NeH) is absent.
Ultravioletevisible (EtOH, qualitative analysis) in (nm): 386
[n/ *, N]N], 250 [n/
*, NNN]. 1H NMR (400.0 MHz) in DMSO-
d6 lead(II) triazenide complex, with values in (ppm): 8.27 (d, 2H,
e
values indicate that the bonds have a partial double-bond char-
C
acter, implying a relocation of the
p electrons in the chains N11e
n
n
N12]N13 (selected distances and angles are discussed in Table 2).
Observing the packing of the molecule, one can see that the
H13A atom of the triazene chain produces intermolecular in-
teractions with forked receptor geometry (D1, H1,H2, D2)/A
(D ¼ donor atom, A ¼ receptor atom) [21,23] [16,18]. Consequently,
the molecules of the triazene are related via these connections. The
atoms considered to be donor atoms are N13 (H13AeN13) and C22
(C22eH22), where as the receptor is the O1 oxygen atom of the N-
oxide function (Fig. 2). Distances and angles are described in
Table 3.
Crystal data and the experimental conditions for
[PbII(RC6H4NNNC6H5)2] (R ¼ p-NO2) are given in Table 1. Selected
bond distances and angles are listed in Table 2 and Fig. 3 shows the
molecular structure of the single complex in a thermal ellipsoid
representation with 40% thermal ellipsoids (using DIAMOND soft-
ware [20]).
n
n
n
l
p
s
d
J ¼ 8.1 Hz); 8.16 (d, 2H, J ¼ 7.6 Hz); 7.70 (d, 2H, J ¼ 8.1 Hz); and 7.61
(dd, 3H, J ¼ 7.5 Hz).
3. Crystallography
Data were collected using a Bruker APEX II CCD area-detector
diffractometer and employing graphite-monochromatized MoK
a
radiation. The structures from the ligand and the complex were
solved by direct methods using SHELXS-97 [18]. Subsequent
Fourier-difference map analyses yielded the positions of the non-
hydrogen atoms. Refinements were done with the SHELXL-97
package [19]. All refinements were done by full matrix least-
In a single complex, two deprotonated 1,3-diaryl-substituted
triazenide ligands are inversely coordinated to one Pb(II) ion by
means of two primary PbeN bonds and two primary PbeO in-
teractions (Fig. 3). The asymmetric unit is formally related with just
two molecules of the ligand and the Pb(II) ion. Thus, the complex is
not planar, but has highly distorted quadratic geometry.
The translation operated moieties are stacked unidimensionally
Table 3
ꢀ
ꢀ
Secondary interactions: lengths (A) and angles ( ) for N-oxide ligand complex.
DeH/Aa
DeH
H/A
D/A
DeH/A
N13eH1/O1b
C26eH26/O3b
0.861(3)
0.930(2)
2.185(1)
2.570(1)
2.957(2)
3.304(3)
149.15(11)
136.10(13)
along the crystallographic b axis through Pb-h6earene
p in-
a
D ¼ donor and A ¼ acceptor. Symmetry operations used to generate equivalent
teractions between the Pb(II) ion and carbons atoms of the phenyl
rings of neighboring complexes.
atoms.
b
1 ꢁ x, ꢁy, ꢁz.
Iglesias, Bernardo A.
