Dinuclear tin(II) complex of a bulky cis-oxamide: Synthesis, characterization, crystal structure, and DFT studies

Article abstract of DOI:10.1002/zaac.201200212

The reaction of the di-lithiated oxamide of 1 with two equivalents of SnCl₂ provided the tin trans-oxamide 3. In solution, spectroscopic analysis suggests exclusively the formation of a trans-oxamide (trans-3). However, the solid state shows an

Full text of DOI:10.1002/zaac.201200212

Job/Unit: Z12212
/KAP1
Date: 31-07-12 10:25:12
Pages: 6
ARTICLE
DOI: 10.1002/zaac.201200212
Dinuclear Tin(II) Complex of a Bulky cis-Oxamide: Synthesis,
Characterization, Crystal Structure, and DFT Studies
Marisol Ibarra-Rodríguez,[a] H. V. Rasika Dias,*[b] Víctor M. Jiménez-Pérez,*[a]
Blanca M. Muñoz-Flores,[a] Angelina Flores-Parra,[c] and Sonia Sánchez[c]
Dedicated to Professor Herbert W. Roesky on the Occasion of His Birthday
Keywords: Oxamides; Tin; 119Sn NMR spectroscopy; Crystal structure; Density functional calculations
Abstract. The reaction of the di-lithiated oxamide of 1 with two equiv-
alents of SnCl2 provided the tin trans-oxamide 3. In solution, spectro-
scopic analysis suggests exclusively the formation of a trans-oxamide
oxamide (trans-3) was performed however, at lower temperature no
additional signal was observed, which confirmed the absence of a dy-
namic equilibrium. Dispersion-corrected density functional calcula-
(trans-3). However, the solid state shows an atypical cis-oxamide (cis- tions revealed that the cis conformation of this tin(II) oxamide complex
3), where the oxamide fragment acts as an anti-Janus head ligand. An
is more stable than the trans isomer by 1.4 kcal·mol–1.
119Sn-NMR variable temperature experiment ([D8]THF) of the trans-
amide nitrogen and the gallium atom.[16] Based on that, Zi-
emkowska et al. reinvestigated the reactions of aluminum ox-
amide complexes varying the substituents on nitrogen atoms
and a mixture of two configurational isomers was determined
by 13C-NMR spectroscopy.[17]
Introduction
N,NЈ-Disubstituted oxamides have been of great importance
to crystal engineering,[1] pharmaceutical,[2] and coordination
chemistry.[3] Oxamides as ligands show a diversity of bonding
modes (Scheme 1)[4–6] and several synthetic advantages as: (i)
high yields, (ii) simple synthetic routes, (iii) short time reac-
tions, and (iv) easy isolation. Particularly, trans-oxamide (III)
and cis-oxamide (VIII) could be considered as Janus head[7]
and anti-Janus head complexes, respectively. Both conforma-
tions with transition metal oxamides have been reported.[8] Ox-
amides with anti-Janus head conformation are typically syn-
thesized in a step-wise pathway.[9] On the other hand, com-
plexes with main group elements (B, Al, Ga, Si, Ge, Sn, and
Sb) in trans conformation were synthesized,[10–15] whereas
those with cis conformation are quite scarce. In 1977 Fischer
and Stezowski reported that both isomers III and VIII come
from the same reaction and the configurational isomerism de-
pends upon both size and nature of the substituents at the ox-
Scheme 1. Different coordination modes for oxamide ligands.
* Dr. V. M. Jiménez-Pérez, H. V. Rasika Dias
Fax: +52-81-83762929
Thus, in this contribution we describe the synthesis and mo-
lecular structure of the first dinuclear SnII-cis-oxamide com-
plex. 119Sn VT-NMR and DFT calculations show that disper-
sion in such systems is fundamental to describe correctly the
energetic of the title system.
E-Mail: vjimenezperez@yahoo.com
[a] Facultad de Ciencias Químicas
Universidad Autónoma de Nuevo León, Ciudad Universitaria
Av. Universidad s/n.
Nuevo León, México
[b] Department of Chemistry and Biochemistry
The University of Texas at Arlington
Arlington, Texas 76019–0065, USA
[c] Departamento de Química
Results and Discussion
CINVESTAV
Reaction of oxalylchloride with the corresponding disubsti-
tuted aniline provided the sterically crowded oxamides 1 and
2 in good yields (Scheme 2) as colorless sharp melting crystal-
line materials with good solubility in THF, CHCl3, and
A. P. 14–740
C. P. 07000, D. F. México
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201200212 or from the au-
thor.
Z. Anorg. Allg. Chem. 0000, ᭿,(᭿), 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1

Job/Unit: Z12212
/KAP1
Date: 31-07-12 10:25:12
Pages: 6
H. V. Rasika Dias, V. M. Jiménez-Pérez et al.
ARTICLE
CH2Cl2. The molecular structure of 1, as determined by single- group P21/n. Bond lengths, bond angles, and torsion angles are
crystal X-ray diffraction analysis, is depicted in Figure 1, (se- given in the Supporting Information. The molecular structure
lected bond lengths and angles are given in the Supporting of cis-3 (Figure 2) reveals three interesting features: (a) In con-
Information). The crystal structure of the oxamide 1, crys- trast to the free ligand 1, the oxamide crystallizes in a cis con-
tallized from slow evaporation at room temperature after one formation of point group symmetry C1, e.g., this compound
week, shows trans conformation with C2 symmetry. The low could be considered as an anti-Janus head complex; meaning
symmetry is due to a non-planar array of the aromatic rings that the oxamide fragment consists of two different coordina-
(torsion angle C1–N2–C3–C8
=
66.7°). The C1–O1 tion sites pointing towards opposite directions. (b) It is a dinu-
[1.208(4) Å], C1–N2 [1.327(4) Å], and C1–C11 [1.509(4) Å] clear SnII complex, in which Sn2 is surrounded by two oxygen
bond lengths are slightly shorter than those of similar already atoms; fused cycle SnO2Cl(O), whereas Sn1 is chelated by two
reported oxamides (Me3C6H2NHCO)2, [C–O 1.2188(4) Å, C– nitrogen sites of oxamide ligand; fused cycle SnN2Cl(O). Each
N 1.337(5) Å, C–C 1.5338(3) Å].[18] Reaction of the di-lithi- tin atom is further coordinated to a THF molecule resulting in
ated oxamides of 1 and 2 with two equivalents of SnCl2 in a tetracoordinate pseudo-trigonal bipyramidal arrangement.
THF at low temperature provided, after work-up, compounds The tin electron lone pairs are probably an orbital with a strong
trans-3 and trans-4, respectively, as amorphous materials in s character.[20] Finally, both tetracoordinate (pseudo-tbp) tin
approximately 52% yield (Scheme 2).
atoms are stereogenic centers and, therefore, an isomeric mix-
ture should be expected; however, the reactions yielded only
one isomer of 36 isomers (3!·3! = 36), which can be considered
as a stereoselective reaction.[21] In the solid state, intermo-
lecular weak interactions forms a dimer of compound cis-2
(Figure 3), where the distance from Sn2 (with less steric de-
mand) to the centroid of the ring C6 is 3.402 Å [η6-(2,6-
Me2C6H3)···Sn2], which less than the sum of the van der Waals
radii (ΣrvdW Sn–C = 3.85 Å)[22] and longer than the Cp*2Sn
distance (2.401 Å).[23] Moreover, both oxamide planes are co-
planar.
Scheme 2. Synthesis of compounds 1–4.
Scheme 3. Configurational isomer of dinuclear SnII cis-oxamide 3 iso-
lated in solid state.
Figure 1. ORTEP view of 1. Thermal ellipsoids are drawn at 30%
probability level.
The room temperature 119Sn NMR spectra of trans-3 and
trans-4, in C6D6, exhibit only one sharp resonance at δ =
–147 ppm (Δν1/2 = 79 Hz) and δ = –190 ppm (Δν1/2 = 84 Hz),
respectively, which indicates a tetracoordinate tin atom with
pseudo-square pyramidal arrangement.[19] At – 80 °C, in
[D8]THF the signals are shifted to δ = –162 ppm (Δν1/2
=
596 Hz) and δ = –226 ppm (Δν1/2 = 432 Hz), respectively. The
observation of exclusively one resonance for each solution is
consistent with the existence in solution of a single species,
either trans-3 or trans-4. Even though cis-3 (Scheme 3) was
never detected in solution, this complex crystallized from the
THF solution of trans-3 at – 20 °C after 2 weeks. The forma-
tion of cis-3 might be explained on the basis of a trans-3 isom-
erization by simultaneous Sn–O and Sn–N bond rupture, rota-
tion about the C–C bond and reformation of Sn–O and Sn–N
Figure 2. Molecular structure of cis-3. Thermal ellipsoids are drawn
bonds. Compound cis-3 crystallizes in the monoclinic space at 50% probability level (hydrogen atoms are omitted for clarity).
2
www.zaac.wiley-vch.de © 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Z. Anorg. Allg. Chem. 0000, 0–0

Job/Unit: Z12212
/KAP1
Date: 31-07-12 10:25:12
Pages: 6
Dinuclear Tin(II) Complex of a Bulky cis-Oxamide
isomer is slightly more stable than the cis form by only
0.5 kcal·mol–1. Adding the dispersion correction, this energy
difference is inverted; now the anti-Janus head complex is
now more stable than the trans form by 1.4 kcal·mol–1. The
absolute dispersion to this isomerization is around 2 kcal·mol–1,
which is large enough to make a decisive contribution in
practice. This indicates that the steric effect is one of the main
factors to stabilize the cis isomer and the dispersion stabiliza-
tion occurs for bulky oxamides. Given that dispersion is al-
ways attractive, it thermodynamically stabilizes large bulky
oxamide complexes compared to small ones.
Finally, the experimentally observed cis structure in a con-
densed phase has one extra can be rationalized taking into ac-
count the difference between the dipole moments of cis and
trans forms. Given the local symmetry of trans-2, it is ex-
pected that the dipole moment in cis-2 should be larger. The
calculated dipole moments are 1.64 and 0.25 D, respectively.
In a condensed phase, the initial aggregation is dominated by
the long-range electrostatic interaction. The stronger dipole-
Figure 3. Dimeric aggregate of cis-3, Sn(2)···C6 (3.402 Å) contact is dipole interaction of a pair, cis-2···cis-2, will drive the system
shown (hydrogen atoms are omitted for clarity).
to a preferential cis arrangement instead of the structure in the
gas phase is quite competitive. This dipole-dipole interactions
Finally, in order to better understand the early results, we and the dispersion contribution will stabilize the cis form in
carried out a series of DFT calculations at the BP86/def2-SVP the solid state.
level. The most relevant geometrical parameters are summa-
rized in Figure 4. The computed bond lengths are in reasonable
Conclusions
agreement with the experimental values. The most significant
changes are observed in the dative bonds, but it is well-known
that these kinds of bonds are shorter in the solid state than in
the gas phase.[24] Interestingly, our calculations indicate the
trans form is slightly more stable as the cis isomer by only
0.5 kcal·mol–1 (including the zero-point energy). The energy
difference is small enough that in principle both isomers could
be observed, as the experiments show. However, how could
we explain the exclusive cis preference?
We described the synthesis, characterization, and X-ray
structures of the first example of a dinuclear SnII anti-Janus
head complex with a bulky cis-oxamide. The calculated geo-
metries are consistent to the X-ray experimental results. Our
calculations show that the absolute dispersion to this isomer-
ization is around 2 kcal·mol–1, stabilizing the anti-Janus head
form. This indicates that the steric effect is one of the main
factors to stabilize the cis isomer and the dispersion interaction
stabilizes bulky oxamides. In the solid state, the dipole-dipole
interactions also contribute in the stabilization of the cis form.
Experimental Section
Materials and General Methods: All manipulations were performed
in a nitrogen atmosphere by using standard Schlenk techniques[27] or
inside a glovebox. The THF was dried with Na/benzophenone prior
to use in a nitrogen atmosphere. Chemical reagents were commercial
available and used as received. Mass spectrum in the EI mode was
recorded at 20 eV with a Hewlett-Packard HP 5989 spectrometer and
high- resolution mass spectra were obtained by LC/MSD TOF on an
Agilent Technologies instrument with APCI as ionization source. IR
spectra were obtained with a FT-IR 1600 Perkin-Elmer. The C6D6 sol-
vent used for NMR measurements was distilled from Na/K alloy prior
to use and CDCl3 used without further purification. Elemental analyses
were performed with the Perkin-Elmer Series II CHNS/O analyzer.
Melting points were obtained with a Mel-Temp II apparatus. NMR
Figure 4. Selected internuclear distances /Å calculated for cis-3 and
trans-3.
Recently, Grimme and co-workers discussed in detail the
importance of the dispersion energy for the thermodynamic
stability of molecules.[25] Given that our ligand has a medium
size, the dispersion contribution could be important. Using the
implementation of Grimme’s DFT-D method for calculating
dispersion corrections for DFT functionals[26] we found re-
1
spectra were recorded with a JEOL GSX 270: H (270.16 MHz), 13C
(67.9 MHz) and JEOL 300 1H (300 MHz), 119Sn (112.07 MHz): instru-
ments all equipped with multinuclear units. Variable temperature
119Sn-NMR spectra were recorded with a Bruker Avance DPX
markable effects. Without added dispersion energy, the trans 400 MHz.
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
3

Job/Unit: Z12212
/KAP1
Date: 31-07-12 10:25:12
Pages: 6
H. V. Rasika Dias, V. M. Jiménez-Pérez et al.
ARTICLE
Crystal Structure Determination: The data for 1 was collected at 6.86%; found: C 76.53, H 9.99, N 7.06%.1H NMR (400.13 MHz,
298(1) K and a suitable crystal of cis-2 was covered with a layer of CDCl3): δ = 8.89 (s, N-H, 2 H), 7.24 (d, 4 H), 7.22 (t, 2 H), 3.08 (sept,
hydrocarbon oil that was selected and mounted with paratone-N oil on
a cryo-loop, and immediately placed in the low-temperature nitrogen δ = 159.67 (C=O, 2C), 145.86 (Cq, C2), 129.83 (Cq, C3), 123.83 (C4),
iPr, 4 H), 1.24 (d, CH3, 24 H) ppm. 13C NMR (100.5 MHz, CDCl3):
stream at 100(2) K. The data for 1 was collected on Siemens P4, with
129.0 (C5), 29.17 (C6), 23.66 (C7) 158.17 (C1), 132.38 (C3), 135.07
a graphite monochromator. The data for cis-3 was recorded with a (C4), 128.4 (C5 and C6), 18.54 (C7) ppm. TOF-MS: [M+]
Bruker SMART APEX CCD area detector system equipped with a C26H36N2O2: 409.2849 a.m.u, found: 409.2851 a.m.u. (Error = -
Oxford Cryosystems 700 Series Cryostream cooler, a graphite mono-
0.002ppm). IR (KBr): ν˜ = 3225 (N–H), 2964 (C–H), 1663 (C=O),
chromator, and a Mo-Kα fine-focus sealed tube (λ = 0.71073 Å). Both 1497 (C–N), 1218 (C–O), 903, 801, 728 cm–1.
structures were solved by direct methods using SHELXS-97[28] and
Synthesis of Complex 3: A solution of n-butyllithium in n-hexane
refined against F2 on all data by full-matrix least-squares with
SHELXL-97.[29]
(1.6 m, 4.22 mL, 6.75 mmol) was added dropwise at 0 °C to a solution
of 1 (0.8 g, 2.7 mmol) in THF (25 mL). After 30 min, a suspension of
SnCl2 (1.02 g, 5.4 mmol) in dry THF (15 mL) was added slowly at –
78 °C. The reaction mixture was slowly warmed to room temperature
and stirred for 16 h. After removal of all volatiles, the residue was
extracted with toluene (10 mL) to yield an orange solution of 2. Yield
0.98 g (52%), M.p. 98 °C. The product is soluble in benzene, toluene
and THF. C18H18N2Cl2O2Sn2·2THF (746.52 g·mol–1): calcd. C 41.83,
H 4.55, N 3.75%; found: C 42.54, H 5.29, N 3.89%. 1H NMR
(300 MHz, C6D6): δ = 7.23 (m, 6 H, H-3 and H-2), 2.20 (s, 12 H, H-
1). 119Sn NMR (112.07 MHz, C6D6): δ = –147 ppm. MS [EI, m/z (%)]
= 701 [M+– 3 CH3 (4)], 533[M+–2Cl, - 2THF (2.5)], 415 [M+–2Cl–
Sn–2THF (8)]. IR (KBr): ν˜ = 2958 (C–H), 1614 (C=O), 1091 (C–O)
cm–1.
Crystal Data for 1: Mr = 296.37, orthorhombic, space group Pcab, a
= 10.016(7) Å, b = 11.773(7) Å, c = 26.129(15) Å, α = 90°, β =
99.142(2)°, γ = 90°, V = 3081(3) Å3, Z = 2, ρ calcd. = 1.278 g·cm–3,
R(reflections) = 0.0735(2699), wR2(reflections) = 0.1774(10119).
Crystal Data for cis-Oxamide 2: Mr = 746.83, monoclinic, space
group P21/n, a = 8.0473(3) Å, b = 11.6507(4) Å, c = 30.9617(11) Å,
α = 90°, β = 93.0780(10)°, γ = 90°, V = 2898.68(18) Å3, Z = 4, ρ
calcd. = 1.711 g·cm–3, R(reflections) = 0.0226(5990), wR2(reflections)
= 0.0236(24134).
Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
numbers CCDC-804037 for 1 and CCDC-803607 for cis-3 (Fax: +44-
1223-336-033; E-Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.ca-
m.ac.uk).
Note: After the work-up, the trans-3 solution was stored in a freezer
at –20 °C for 2 weeks to afford yellow crystals of tin cis-oxamide 3
complex (0.31 g, 15.5%). IR (KBr): ν˜ = 2958 (C–H), 1614.21 (C=O)
and 1568 (C=O), 1095 (C–O) cm–1.
Synthesis of Complex 4: The procedure was similar to the synthesis
of the oxamide 3. Yield 0.88 g (52%), M.p. 190 °C.
C26H34N2Cl2O2Sn2·2THF (858.6 g·mol–1): calcd. C 47.55, H 5.82, N
3.26%; found: C 47.35, H 5.70, N 3.59%. 1H NMR (300 MHz, C6D6):
δ = 7.23 (m, 6 H), 3.60 (sept, iPr, 4 H), 1.25 (s, CH3, 24 H) ppm.
119Sn NMR (112.07 MHz, C6D6): δ = –146.05 ppm. MS [EI, m/z (%)]
= 757 [M+–Cl, (1)], 647 [M+–2Cl, (1)], 525.3 [M+–2Cl-Sn], (36)].
Theoretical Calculations: All structures were fully optimized at the
BP86/def2-SVP level using the Gaussian 03 suite of programs. Every
stationary point was characterized as a local minimum on the potential
energy surface (PES) by a harmonic (frequency) analysis. Zero-point
vibrational energies and thermal corrections to enthalpy were also
computed at the unscaled BP86/def2-SVP level. The dispersion were
included using the implementation of Grimme’s DFT-D method for
calculating dispersion corrections for DFT functionals.[26]
Supporting Information (see footnote on the first page of this article):
Selected bond lengths and angles and details of the X-ray crystallo-
graphic analysis for 1 and cis-3. 1H, 13C, 119Sn NMR spectra for li-
gands and tin(II) complexes.
Synthesis of N,N’-2,6-Dimethylphenyl-oxamide (1): A 250 mL two-
neck-flask containing a solution of oxalyl chloride (1.74 mL, 20 mmol)
in dry THF (30 mL) in a nitrogen atmosphere was cooled in an ice
bath, and a solution 2,6-dimethylaniline of (4.9 mL, 40 mmol) in THF
(40 mL) was slowly added with a dropping funnel. This equipment
was connected to a saturated NaOH solution for the release of HCl. A
white precipitate immediately formed and after 1 h the temperature
raised to room temperature and the resulting solid was recovered by
filtration, washed with H2O (10 mL) and dried overnight in air and
finally in vacuo. Compound 1 was recrystallized from Et2O/THF to
give suitable single crystals for X-ray diffraction study. Yield 5.07 g
(85%), M.p. 235–237 °C. C18H20N2O2 (296.37 g·mol–1): calcd. C
72.95, H 6.80, N 9.45%; found: C 72.71, H 7.26, N 9.41%. 1H NMR
(270 MHz, CDCl3): δ = 8.89 (s, 2 H, H-2), 7.15 (m, 6 H, H-5 and H-
6), 2.27 (s, 12 H, H-7) ppm. 13C NMR (67.93 MHz, CDCl3): δ =
158.17 (C1), 132.38 (C3), 135.07 (C4), 128.4 (C5 and C6), 18.54 (C7)
ppm. TOF-MS: [M+] C18H20N2O2: 297.1598 a.m.u, found: 297.1597
a.m.u (Error = –0.0545 ppm). IR (KBr): ν˜ = 3294 (N–H), 2962-
(C–H), 1665 (C=O), 1497 (C–N), 1220 (C–O), 1039, 802, 672 cm–1.
Acknowledgement
This work was supported by CONACYT (grant 82605). H. V. R. D.
thanks the Robert Welch Foundation (grant Y-1289) for the financial
support. We thank Prof. Dr. Herbert Roesky for his valuable comments
during the preparation of this manuscript. M. I.-R. thanks for a scholar-
ship from CONACYT. We also thank Sylvain Bernès and Daniel
Muñoz-George for performing the X-ray diffraction of 1 and comments
on mathematical calculations respectively.
References
[1] T. L. Nguyen, F. W. Fowler, J. W. Lauher, J. Am. Chem. Soc.
2001, 123, 11057–11064.
[2] R. Bernini, A. Cutolo, A. Irace, P. Spirito, L. Zeni, P. K. Jadhav,
M. Hon-Wah, Tetrahedron Lett. 1996, 37, 1153–1164.
[3] H. Ojima, K. Nonoyama, Coord. Chem. Rev. 1988, 92, 85–277.
[4] a) F. A. Cotton, C. Y. Liu, C. A. Murrillo, D. Villagran, X. Wang,
J. Am. Chem. Soc. 2003, 125, 13564–13575; b) F. A. Cotton, C. Y.
Liu, C. A. Murrillo, Q. Zhao, Inorg. Chem. 2007, 46, 2604–2611.
Synthesis of N,N’-2,6-Diisopropylphenyl-oxamide (2): The pro-
cedure was similar to the synthesis of oxamide 1. Yield 7.59 g (93%),
M.p. 301 °C. C26H36N2O2 (408.52 g·mol–1): calcd. C 76.43, H 8.88, N
4
www.zaac.wiley-vch.de
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 0000, 0–0

Job/Unit: Z12212
/KAP1
Date: 31-07-12 10:25:12
Pages: 6
Dinuclear Tin(II) Complex of a Bulky cis-Oxamide
[5] a) W. Maringgele, G. M. Sheldrick, A. Meller, N. Noltemeyer, [16] P. Fischer, R. Gräf, J. J. Stezowski, J. J. Weidlein, J. Am. Chem.
Soc. 1977, 99, 6131–6132.
Chem. Ber. 1984, 117, 2112–2114; b) L. Cronin, P. A. McGregor,
S. Parsons, S. Teat, R. O. Gould, V. A. White, N. J. Long, N.
Robertson, Inorg. Chem. 2007, 46, 2604–2611; c) B. Kruss, M. L.
Ziegler, Z. Anorg. Allg. Chem. 1973, 401, 89–96.
[17] W. Ziemkowska, E. Jaskowska, E. Zygadlo-Monikowska, M. K.
Cyranski, J. Organomet. Chem. 2011, 696, 2079–2085.
[18] B. Piotrkowska, M. Gdaniec, M. J. Milewska, T. Polon´ski, Crys-
tEngComm 2007, 9, 868–870.
[6] O. S. Wandiga, Pure Appl. Chem. 1999, 71, 1019–1024.
[7] a) F. Armbruster, I. Fernández, F. Breher, Dalton Trans. 2009,
5612–5626; b) I. Krummenacher, I. Fernández, H. Rüegger, F.
Weigend, F. Breher, Dalton Trans. 2009, 5335–5347.
[8] R. Ruiz, J. Faus, F. Lloret, M. Julve, Y. Journaux, Coord. Chem.
Rev. 1999, 193–195, 1069–1117.
[9] a) J.-K. Tang, Y. O.-Yang, H.-B. Zhou, Y.-Z. Li, D.-Z. Liao, Z.-
H. Jiang, S.-P. Yan, P. Cheng, Cryst. Growth Des. 2005, 5, 813–
819; b) Y. Journaux, J. Sletten, O. Kahn, Inorg. Chem. 1985, 24,
4063–4069.
[19] B. Wrackmeyer, Annu. Rep. NMR Spectrosc. 1985, 16, 73–186.
[20] Y. Mizuhata, T. Sasamori, N. Tokitoh, Chem. Rev. 2009, 109,
3479–3511.
[21] V. M. Jiménez-Pérez, H. Noeth, A. Ariza, A. Flores-Parra, R.
Contreras, J. Organomet. Chem. 2006, 691, 1584–1589.
[22] B. Bondi, J. Phys. Chem. 1964, 68, 441–451.
[23] P. Jutzi, F. Kohl, P. Hoffmann, C. Kruger, Y.-H. Tsay, Chem. Ber.
1980, 113, 757–767.
[24] a) G. Merino, V. I. Bakhmutov, A. Vela, J. Phys. Chem. A 2002,
106, 8491–8494; b) M. Buhl, T. Steinke, P. Schleyer, R. Boese,
Angew. Chem. Int. Ed. Engl. 1991, 30, 1160–1161; c) K. R. Leo-
pold, A. W. Burns, J. Am. Chem. Soc. 1993, 115, 11622–11623;
d) V. Jonas, G. Frenking, T. M. Reetz, J. Am. Chem. Soc. 1994,
116, 8741–8756.
[25] S. Grimme, J. Comput. Chem. 2006, 27, 1787–1799.
[26] S. Grimme, R. Huenerbein, S. Ehrlich, ChemPhysChem 2011, 12,
1258–1261.
[10] U. Beckmann, E. Bill, T. Weyhermüller, K. Wieghardt, Eur. J.
Inorg. Chem. 2003, 1768–1777.
[11] W. Ziemkowska, J. Kochanowski, M. K. Cyranski, J. Organomet.
Chem. 2010, 695, 1205–1209.
[12] V. M. Jiménez-Pérez, C. Camacho-Camacho, A. Ramos-Or-
ganillo, R. Ramírez-Trejo, A. Peña-Hueso, R. Contreras, A. Flo-
res-Parra, J. Organomet. Chem. 2007, 692, 5549–5554.
[13] R. Contreras, V. M. Jiménez-Pérez, C. Camacho-Camacho, M.
Güizado-Rodríguez, B. Wrackmeyer, J. Organomet. Chem. 2000,
604, 229–233.
[14] V. M. Jiménez-Pérez, C. Camacho-Camacho, M. Güizado-
Rodríguez, H. Nöth, R. Contreras, J. Organomet. Chem. 2000,
604, 283–293.
[27] D. F. Shriver, M. A. Drezdon, The Manipulation of Air-Sensitive
Compounds, 2nd ed., Wiley, New York, 1986.
[28] G. M. Sheldrick, Acta Crystallogr., Sect. A 1990, 46, 467–473.
[29] G. M. Sheldrick, SHELX-97, Program for the Solution and Re-
finement of Crystal Structures, Universität Göttingen, Göttingen,
Germany, 1997.
Received: May 9, 2012
[15] V. M. Jiménez-Pérez, Dr. Phil. Thesis, CINVESTAV-IPN, 2005.
Published Online: ᭿
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
5

Job/Unit: Z12212
/KAP1
Date: 31-07-12 10:25:12
Pages: 6
H. V. Rasika Dias, V. M. Jiménez-Pérez et al.
ARTICLE
M. Ibarra-Rodríguez, H. V. Rasika Dias,* V. M. Jiménez-
Pérez,* B. M. Muñoz-Flores, A. Flores-Parra,
S. Sánchez ......................................................................... 1–6
Dinuclear Tin(II) Complex of a Bulky cis-Oxamide: Synthesis,
Characterization, Crystal Structure, and DFT Studies
6
www.zaac.wiley-vch.de
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 0000, 0–0