Berry exchange coordinate geometry in 3-methyl-2-hydroxycyclopenten-1-one tin esters

Article abstract of DOI:10.1016/j.jorganchem.2005.12.036

Three new penta- and hexacoordinated tin compounds (1-3) were prepared from PhSnCl₃, Ph₂SnCl₂ and Ph₃SnOH and 3-methyl-2-hydroxy-2-cyclopenten-1-one (L). Compounds 1-3 were characterized by IR, mass spectra, elemental analysis, ¹H, ¹³C, and ¹¹⁹Sn NMR. The ligand acts as a bidentate giving the tin esters and coordinating the tin by the carbonyl group. Compound 1 (PhSnCl₂L ? EtOH) has an hexacoordinated tin atom, with an octahedral distorted geometry, which is a stereogenic center. Compounds 2 (Ph₂SnClL) and 3 (Ph₃SnL) have pentacoordinated tin atoms. The structures were determined by X-ray diffraction analyses. In the solid state 1 presents a racemic pair, linked by strong hydrogen bonds and 2 and 3 Berry exchange coordinate geometry.

Full text of DOI:10.1016/j.jorganchem.2005.12.036

Journal of Organometallic Chemistry 691 (2006) 1590–1597
www.elsevier.com/locate/jorganchem
Berry exchange coordinate geometry in
3-methyl-2-hydroxycyclopenten-1-one tin esters
a
b
b
´
´
Carlos Camacho-Camacho , Victor M. Jimenez-Perez , Juan Carlos Galvez-Ruiz ,
b,
b,
*
Angelina Flores-Parra *, Rosalinda Contreras
a
Departamento de Sistemas Biolo´gicos, Universidad Auto´noma Metropolitana, Xochimilco, Calzada del Hueso 1100,
Colonia Villa Quietud, C.P. 04960 Mexico, D.F., Mexico
b
Departamento de Qu´ımica, Cinvestav, A.P. 14-740, C.P. 07000 Mexico, D.F., Mexico
Received 7 December 2005; accepted 8 December 2005
Available online 3 February 2006
Abstract
Three new penta- and hexacoordinated tin compounds (1–3) were prepared from PhSnCl3, Ph2SnCl2 and Ph3SnOH and 3-methyl-2-
hydroxy-2-cyclopenten-1-one (L). Compounds 1–3 were characterized by IR, mass spectra, elemental analysis, 1H, 13C, and 119Sn NMR.
The ligand acts as a bidentate giving the tin esters and coordinating the tin by the carbonyl group. Compound 1 (PhSnCl2L Æ EtOH) has
an hexacoordinated tin atom, with an octahedral distorted geometry, which is a stereogenic center. Compounds 2 (Ph2SnClL) and 3
(Ph3SnL) have pentacoordinated tin atoms. The structures were determined by X-ray diffraction analyses. In the solid state 1 presents
a racemic pair, linked by strong hydrogen bonds and 2 and 3 ‘‘Berry exchange coordinate’’ geometry.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Berry exchange coordinate geometry; 3-Methyl-2-hydroxycyclopenten-2-one tin compounds; Penta- and hexacoordinated tin derivatives
1. Introduction
We have reported a series of organotin tropolonate
compounds, which demonstrate that the tropolone may
give different tin derivatives, depending on the reagents
ratio and on the number of organyl–tin bonds, Scheme 1.
The reported derivatives containing from one to three trop-
olone molecules, and with tin coordination numbers vary-
ing from five to seven, were submitted to detailed NMR
and X-ray diffraction studies [10]. It has been reported that
the tin atom could extend its coordination number until
eight by bonding to four tropolone molecules [11]. The
tropolone ligand in tin compounds present two O–Sn
We are interested in the structural analysis of hyperva-
lent tin compounds and in the role of the coordination of
oxygen atoms in expanding the tin valence. An important
question in these studies is the understanding of the O–Sn
bond nature. In this context, we have investigated the use
of 3-methyl-2-hydroxy-cyclopenten-1-one as a versatile
ligand for tin-organometallic compounds because it could
act as a bidentate dione or ketoenol giving stable coordina-
tion structures. An additional interest in the a-hydroxy-
ketones is their application as food additives [1] or
ribonucleotide reductase inhibitor [2] or as antifungal or
antibacterial agents [3]. Some a-hydroxyketones derived
from Sn, Zn and Cu are used in oral care formulations
[4–7]. And some others bonded to Sn(IV) are promising
in the treatment of cancer [8,9].
˚
bonds, almost similar in length (2.12–2.35 A). In this
context, the Ph3Sn(tropolone), merits some comments,
Fig. 1: it presents a tbp distorted geometry, the angle
between the apical atoms (C8–Sn–O2) is 156.93ꢁ, whereas
equatorial angles are C14–Sn–C20 117.67ꢁ, C20–Sn–O1
113.71ꢁ and O1–Sn–C14 123.37ꢁ and the 119Sn NMR
data correspond to a pentacoordinated compound [d =
ꢀ181.9 ppm 1J(119Sn, 13C) = 668.3 Hz]. Our interest to
understand the bond between the carbonyl group and the
*
Corresponding authors. Tel.: +55 5061 3720; fax: +55 5061 3389.
E-mail address: aflores@cinvestav.mx (A. Flores-Parra).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.12.036

C. Camacho-Camacho et al. / Journal of Organometallic Chemistry 691 (2006) 1590–1597
1591
O
O
O
O
O
SnR2
SnR
SnR3
O 2
3
R = n-Bu or Ph
Scheme 1. Reported tin compounds derived from 1,2-tropolone [10].
Fig. 2. X-Ray data of an oxalamide diphenyltin ester [13] have been used
for atomic charges calculation [Sn1, +0.96; Sn2, +0.97; N1, ꢀ0.35; N2,
ꢀ0.38; O1, ꢀ0.60; O2, ꢀ0.66; O3, ꢀ0.65; O4, ꢀ0.63; C10, +0.39; C11,
+0.38; C12, +0.15; C13, +0.28; C18, +0.01; C24, +0.02; C30, +0.02 and
C36, +0.03].
cyclopentadione as it was clear from examination of IR
and NMR spectra in CDCl3, their data in Tables 1 and 2
Fig. 1. X-ray data of triphenyltropolone compound [10] have been used
for calculation of atomic charges [Sn, +0.98; O1, ꢀ0.60; O2, ꢀ0.59; C1,
+0.30; C2, ꢀ0.13; C3, ꢀ0.17; C4, ꢀ0.15; C5, ꢀ0.18; C6, ꢀ0.14; C7, +0.31;
C8, ꢀ0.02; C14, ꢀ0.02 and C20, ꢀ0.001]. Angles (ꢁ) around tin atom
inform about a distorted bpt geometry: O2–Sn–O1, 71.39ꢁ; O2–Sn–C14,
87.44ꢁ; O2–Sn–C20, 88.61ꢁ; O1–Sn–C8, 85.80ꢁ; C8–Sn–C14, 102.85ꢁ; C8–
Sn–C20, 104.18ꢁ and the C–C bond lengths of the tropolone ring show
that it is a p-delocalized system C1–C2 1.394, C2–C3 1.381, C3–C4 1.378,
1
were assigned by a H–13C COLOC experiment.
2. Results and discussion
Three new Sn(IV) compounds (1–3) from 3-ethyl-2-
hydroxy-2-cyclopenten-1-one and PhSnCl3, Ph2SnCl2 and
Ph3SnOH were synthesized, Scheme 2. The reactions were
performed in ligand/tin molar ratios of 3/1, 2/1 and 1/1,
˚
C4–C5 1.397, C5–C6 1.368, C6–C7 1.414 and C7–C1 1.464 A.
1
tin atom, motivated us to use the reported X-ray diffraction
data [10] of the Ph3Sn(tropolone) in order to calculate its
atomic charges, Fig. 1. The atomic charges and the C–C
bond lengths indicated that coordination favored the delo-
calization of the positive charge affording a stable tin com-
pound. Some reported metal derivatives of tropolonates
(Na(trop), Ir(trop)3 and Rh(trop)3) studied by NMR
showed that 13C NMR spectra C1 and C2 are equivalent
(d 13C, 184.7, 188.6 and 187.9 ppm, respectively) as a con-
sequence of a delocalized aromatic system where both
carbonyl groups show a partial double bond character [12].
Another example of a strong tin carbonyl coordination
has been found in diphenol–oxalamide tin esters, where
C@O–Sn bonds are very short (O1–Sn1 2.04; O2–Sn1
respectively. The products were characterized by H, 13C,
and 119Sn NMR, IR, mass spectra and elemental analysis.
Tin compounds were recrystallized from CH2Cl2/ethanol
and suitable crystals for their X-ray diffraction studies were
obtained.
2.1. Spectroscopic analysis
Spectroscopic analyses have shown in compounds 1–3
that one chlorine or one OH group was substituted by
one hydroxyketone molecule. In the IR spectra the stretch-
ing C@O bands indicate the tin coordination, the free
ligand forms a strong hydrogen bond and it is also found
in the same range of frequencies. [m(C@O): free ligand
1655.0; 1 1647.1; 2 1658.3 and 3 1679.2 cmꢀ1]. The trend
indicate that C@O–Sn coordination becomes weaker in
going from 1 to 3. The mass spectra of compounds 1–3 cor-
respond to the proposed structures.
˚
2.29 and O3–Sn2 2.21 A), almost as covalent bonds (O1–
˚
Sn1 2.04 and O4–Sn2 2.06 A) and the resulting positive
charges are distributed in the oxalamide delocalized system
[13], Fig. 2.
In order to continue with our research, we decided to
investigate the 3-methyl-2-hydroxy-2-cyclopenten-1-one
and to examine the tin carbonyl coordination. The penta-
cyclic ketoenol is the stable tautomer of the 3-methyl-1,2-
1H, 13C and 119Sn NMR data of 1–3 are listed in Tables
1 and 2. The assignment of the resonances of the phenyl
n
groups was based on their J(13C, 117/119Sn) coupling con-
stants. In solution the 119Sn chemical shifts of 1–3, the

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C. Camacho-Camacho et al. / Journal of Organometallic Chemistry 691 (2006) 1590–1597
Table 1
13C and 119Sn NMR data of compounds 1–3, (d, ppm) and [nJ(13C,119/117Sn), Hz] in CDCl3 at 25 ꢁC
Compound
Free ligand
1a
2
3
25 ꢁC
ꢀ90 ꢁC
C6
C4
C5
C3
C2
C1
14.1
27.1
32.1
149.3
145.9
203.7
16.4
28.8
30.5 [30]
156.6
152.4 [70]
210.0 [83.4]
15.5
28.5
30.5
153.3
150.5 [30.5]
210.7
15.0
27.1
31.1
152.3 [10]
144.5 [21.3]
206.4
15.2
27.1
31.1
151.3
142.1
207.4
Ci
137.2 [1230/1123]
135.2 [63.5]
132.0 [31]
141.0 [935/894]
136.2 [60.5]
130.6 [17.7]
128.9 [89]
142.2 [657/628]
137.1 [48]
129.5 [12.8]
128.6 [62]
142.1 [658/630]
137.2 [45.3]
129.9
Co
Cp
Cm
129.9 [84.5]
128.7 [61.4]
119Sn
–
ꢀ407.6
ꢀ143.6
ꢀ114.1
ꢀ113.5
a
Ethyl group signals appear at: 58.9 and 18.5 ppm.
1
coordination number six is deduced for compound 1 (d
119Sn = ꢀ407.6 ppm), whereas for 2 and 3 (ꢀ143.6 and
ꢀ114.1 ppm, respectively) the resonances are in between
the tetra- and pentacoordination, this could indicate that
a possible internal coordination does not have a significant
effect [14,15]. However, an indication of the coordination
number can be found in the J(119Sn,13C) of the ipso-car-
bon of the phenyl groups, of 1 (1230 Hz), which is consid-
ered adequate for a six coordinated compound [for
example, the Ph2Sn(tropolone)2 has a coupling constant
of 939.7 Hz [10,14,15]] whereas for compounds 2 and 3
their coupling constants (935 and 657 Hz) correspond to
pentacoordinated compounds, as it can be validated by
comparison with the coupling constant value (668.3 Hz)
reported for the pentacoordinated Ph3Sn(tropolone) [10].
The assignment of the proton resonances for 1–3 was
based in 1H–13C COLOC experiments, and the phenyl pro-
tons, in all cases, appear as complex patterns.
Table 2
1H NMR data of compounds 1–3 (d, ppm) [3J(1H,119Sn), Hz], in CDCl3 at
25 ꢁC
Chemical shifts in 13C spectra indicate that the tin atom
is bonded to the enol tautomer, C2 signals [152.4 (1), 150.5
(2) and 144.5 ppm (3)] are characteristic for an enol C–O
bond. All compounds exhibit a double C@O bond [210.0
(1), 210.7 (2) and 206.5 ppm (3)]. A 119Sn variable temper-
ature experiment was performed on compound 3, in order
to check if at low temperature the tin resonance would
change to lower frequencies, due to a better Sn–O coordi-
nation; however, we have not found evidence of any differ-
ence in the tin chemical shift at ꢀ80 ꢁC, this result indicates
that coordination cannot be stronger.
Compound Free
liganda
1b
2
3
25 ꢁC
ꢀ90 ꢁC
H4
H5
H6
Ho
2.38 m 2.76 bc
2.34 m 2.70 bc
2.54 b
2.60 b
2.11 s
2.38 s
2.38 s
2.08 s
2.32 bc
2.36 bc
2.03 s
1.94 s
2.29 s
2.2. X-ray diffraction structures
7.7 m [40] 7.95 m [78] 7.78 m [54] 7.75 m
[57.8]
Compounds 1 and 2 crystallized in the orthorhombic
system, space groups Pcab and P21/cn, respectively. The
crystals of compound 3 were monoclinic with space group
Cc. Relevant structural parameters are summarized in
Table 3.
Hm,p
7.5 m
7.42 m
7.40 m
7.39 m
a
d (ppm) Hydroxy group: 7.15 ppm s.
Ethyl group: 3.73 (q, 7.6), 1.25 ppm (t, 7.6).
Close to the slow exchange limit. Coupling constant in Hz J(1H, H)
b
c
n
1
in parentheses. Abbreviations: s, singlet; m, complex pattern; b, broad.

C. Camacho-Camacho et al. / Journal of Organometallic Chemistry 691 (2006) 1590–1597
1593
OH
H3C
O
PhSnCl3
EtOH
Ph2SnCl2
EtOH
Ph3SnOH
toluene
Cl
H
Cl
O
8
7
CH3
Sn
O
Cl
Sn
O
O
Sn
O
6
2
CH3
O
CH3
CH3
3
O
1
4
5
1
2
3
Scheme 2. Synthesis of compounds 1–3.
The X-ray diffraction structures of compounds 1–3 show
that the ligand combines a single bond Sn–O2 [2.109(3) A
ered that the coordination bond in compound 3 is too long,
but literature search showed data for apical O–Sn bonds
with monodentate ligands, in pentacoordinated com-
pounds, which present bonds as long as 2.48–2.51 A [16–
18]. Therefore, the distance found for O–Sn in compound
˚
˚
˚
1, 2.032(4) and 2.034(4) A 2, 2.032(3) A 3] and a coordina-
˚
˚
tive bond C@O1 ! Sn [2.349(3) A 1, 2.342(3) and
˚
˚
2.359(3) A 2, 2.630(3) A 3], Tables 4–6. It could be consid-
Table 3
Crystal and data collection parameters of compounds 1–3
Compound
1
2
3
Empirical formula
Formula weight
Crystal size (mm)
Crystal system
Space group
C14H17Cl2O3Sn
422.87
0.25 · 0.28 · 0.30
Orthorhombic
Pcab
C18H17ClO2Sn
419.46
0.12 · 0.28 · 0.4
Orthorhombic
P21cn
9.22850(10)
12.90250(10)
29.9390(4)
90.00
90.00
90.00
3564.86(7)
8
1.563
C24H22O2Sn
461.11
0.12 · 0.28 · 0.42
Monoclinic
Cc
˚
a (A)
14.400(3)
13.445(3)
16.760(3)
90.00
90.00
90.00
3244.9(11)
8
15.754(3)
16.847(3)
8.105(2)
90.00
104.63(3)
90.00
2081.4(7)
4
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Z
qcalc (mg/mꢀ3
)
1.731
1.907
1672
1.471
1.242
928
l (mmꢀ1
F(000)
)
1.587
1664
Index range
ꢀ16 6 h 6 14, ꢀ17 6 k 6 17,
ꢀ9 6 h 6 11, ꢀ16 6 k 6 13,
ꢀ37 6 l 6 36
52.72
ꢀ18 6 h 6 18, ꢀ19 6 k 6 21,
ꢀ20 6 l 6 20
56.02
ꢀ9 6 l 6 10
52.70
2h (ꢁ)
Temperature (K)
Reflections collected
Reflections unique
Reflections observed (4r)
Rint
293(2)
16426
3295
2451
0.0723
182
0.02970/3.35490
1.074
0.0354
0.0743
0.609
293(2)
32177
6454
4373
0.0626
398
0.03060/0.00
0.980
0.0351
293(2)
6557
3596
3231
0.0355
210
0.03260/0.85150
1.058
0.0320
0.0765
0.600
Variables
Weighting schemea x/y
Goodness-of-fit
Final R (4r)
Final wR2
Largest res. peak (e/A
0.0604
0.663
ꢀ3
˚
)
2
a
1wꢀ1 ¼ r2F 2o þ ðxPÞ þ yP; P ¼ ðF o2 þ 2F 2c Þ=3.

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C. Camacho-Camacho et al. / Journal of Organometallic Chemistry 691 (2006) 1590–1597
Table 4
Table 5
Selected bond lengths (A) and angles (ꢁ) determined by X-ray analysis of 2
˚
˚
Selected bond lengths (A) and angles (ꢁ) determined by X-ray analysis of 1
Bond lengths
Bond angles
Sn1–O1
Sn1–O2
Sn1–Cl1
Sn1–Cl2
Sn1–C7
C1–C2
C2–C3
C3–C4
C4–C5
C5–C1
C1–O1
C2–O2
2.349(3)
2.109(3)
2.313(1)
2.474(1)
2.183(4)
1.432(6)
1.419(6)
1.543(7)
1.539(8)
1.563(7)
1.286(5)
1.418(5)
O1–Sn1–Cl1
O1–Sn1–Cl2
O1–Sn1–O3
O2–Sn1–C7
O2–Sn1–Cl1
O2–Sn1–O3
O3–Sn1–Cl1
O3–Sn1–C7
C7–Sn1–Cl1
C7–Sn1–Cl2
Cl1–Sn1–Cl2
82.51(9)
165.66(8)
86.4(1)
166.1(1)
85.87(8)
83.3(1)
166.1(1)
86.6(1)
102.4(1)
98.5(1)
Bond lengths
Bond angles
101.1(4)
Cl1–Sn1
C1–O1
C2–O2
2.412(1)
1.243(7)
1.357(7)
2.113(6)
2.112(7)
2.342(3)
2.032(4)
2.418(1)
1.243(6)
1.329(7)
2.104(7)
2.133(6)
2.359(3)
2.034(4)
O2–Sn1–C13
O2–Sn1–C7
C13–Sn1–C7
O2–Sn1–O1
C13–Sn1–O1
C7–Sn1–O1
O2–Sn1–Cl1
C13–Sn1–Cl1
C7–Sn1–Cl1
O1–Sn1–Cl1
O4–Sn2–C30
O4–Sn2–C31
C30–Sn2–C31
O4–Sn2–O3
C30–Sn2–O3
C31–Sn2–O3
O4–Sn2–Cl2
C30–Sn2–Cl2
C31–Sn2–Cl2
O3–Sn2–Cl2
118.1(2)
113.7(2)
125.6(3)
76.6(1)
86.0(2)
90.9(2)
88.1(1)
97.6(2)
99.2(1)
164.2(1)
116.9(2)
112.8(2)
127.7(2)
76.0(1)
86.6(2)
90.3(2)
88.0(1)
98.5(2)
98.5(2)
163.8(1)
C7–Sn1
C13–Sn1
O1–Sn1
O2–Sn1
Cl2–Sn2
C19–O3
C20–O4
C30–Sn2
C31–Sn2
O3–Sn2
O4–Sn2
3 could be considered as a weak coordination bond, but
nevertheless with a physical meaning.
In compound 1, the tin atom is six-coordinated, it is
linked to one ligand molecule, two Sn–Cl bonds, a Sn–Ph
group and a Sn-coordinated ethanol molecule, Fig. 3. A
similar tin connectivity was also reported in hexacoordi-
nated oxalamide tin esters [19]. The distorted octahedral
tin geometry is a consequence of the five membered ring
chelate, the atoms in anti position have angles smaller than
180ꢁ [O1–Sn1–Cl2 165.66(8)ꢁ, O2–Sn1–C7 166.1(1)ꢁ and
O3–Sn1–Cl1 166.1(1)ꢁ].
The tin atom in compound 1 is a stereogenic center and
therefore 12 possible isomers could be expected, however
only two enantiomers were found in the solid state. The
enantiomers form a racemic pair through very strong
˚
hydrogen bonds (1.96 A) between the proton of the ethanol
bipyramid, which can be depicted as a ‘‘Berry exchange
coordinate’’ [20], because the geometry distortion is formed
by the approach of the carbonyl oxygen atom to the tin
atom in order to form a tbp; however, a perfect trigonal
bypiramid is nor reached because of the ring tension and
the Lewis acid character of the tin atom. For compound
2 the apical positions are occupied by the oxygen of the
carbonyl and a chlorine atom [O1–Sn1–Cl1 164.2(1)ꢁ and
O3–Sn2–Cl2 163.8(1)ꢁ], Fig. 4. One oxygen atom and two
phenyl groups are in equatorial, they form angles not far
from 120ꢁ [O4–Sn2–C30 116.9(2)ꢁ, C30–Sn2–C31
127.7(2)ꢁ and O4.Sn2–C31 112.8(2)ꢁ]. The angles formed
by the carbonyl oxygen O3 and the equatorial atoms are
lesser than 90ꢁ [O3–Sn2–O4 76.0(1)ꢁ, O3–Sn2–C30
and the oxygen O2, the distance between both oxygen
0
˚
atoms (O2–O3 ) is 2.67 A. The hydrogen bonds linking
the dimer are forming an eight membered ring [O2–Sn–
˚
O3–H]2, Fig. 3. One Sn–Cl bond (2.313 A) is in trans posi-
˚
tion to the Sn–OHEt bond (2.122 A) both are the shortest
˚
bonds, whereas the longest are the O1–Sn (2.349 A) and
˚
Sn–Cl2 (2.474(2) A). The phenyl group is in the plane
formed by the tin atom, the ligand and Cl2; this fact is
attributed to two intramolecular hydrogen bonds O1–
˚
˚
H12 (2.561 A) and Cl2–H8 (3.020 A). Cl1 atom has two
˚
intermolecular hydrogen bonds with H4A (2.923 A) and
with H14A (2.774 A).
˚
Compounds 2 and 3 have pentacoordinate tin atoms,
their geometry can be considered as a distorted trigonal

C. Camacho-Camacho et al. / Journal of Organometallic Chemistry 691 (2006) 1590–1597
1595
Table 6
Selected bond lengths (A) and angles (ꢁ) determined by X-ray analysis of 3
˚
Fig. 4. One structure of compound 2 and the intramolecular hydrogen
bonds.
Bond lengths
Bond angles
of 2 are associated in the solid state by forming weak coor-
dinative hydrogen bonds via the atoms C11H–O4
(2.705 A). In both molecules the planes of the phenyl
groups are oriented in order to approach the ortho aro-
matic protons to the apical oxygen and chlorine atoms giv-
ing four hydrogen bonds.
Sn1–O1
Sn1–O2
Sn1–C7
Sn1–C13
Sn1–C19
C1–C2
C2–C3
C3–C4
C4–C5
C5–C1
C1–O1
C2–O2
2.630(3)
2.032(3)
2.163(4)
2.146(4)
2.139(4)
1.441(1)
1.318(9)
1.496(1)
1.479(1)
1.510(1)
1.238(9)
1.346(7)
O2–Sn1–C19
C19–Sn1–C13
C19–Sn1–C7
O2–Sn1–C7
O2–Sn1–C13
C13–Sn1–C7
O1–Sn1–C7
116.65(2)
118.91(1)
104.9(2)
91.9(2)
112.9(2)
106.9(2)
162.69
˚
Compound 3 has three phenyl groups and one ligand, its
geometry is similar to that found in 2, Fig. 5. The oxygen
O1 and a phenyl groups are in apical positions (O1–Sn–
C7 is 162.69ꢁ) and the angles for the three equatorial sub-
stituents are O2–Sn–C13 112.9(2)ꢁ, C13–Sn–C19 118.91(1)ꢁ
and C19–Sn–O2 116.65(2)ꢁ. As expected, the angles formed
between the apical oxygen O1 and three equatorial atoms
[O1–Sn–O2 71.84ꢁ, O1–Sn–C13 83.42ꢁ, O1–Sn–C19
80.27ꢁ] are smaller than 90ꢁ, whereas the angles with the
apical atom C7 [C7–Sn–C13 106.9(2)ꢁ, C7–Sn–O2
91.9(2)ꢁ and C7–Sn–C19 104.9(2)ꢁ] are larger than 90ꢁ,
Table 6. In compound 3, the phenyl group in apical is
aligned with the plane of the ligand in order to form a
86.6(2)ꢁ and O3–Sn2–C31 90.3(2)ꢁ], whereas the angles
formed between the chlorine and the equatorial atoms
are more open than 90ꢁ [Cl2–Sn2–O4 88.0(1)ꢁ, Cl2–Sn2–
C30 98.5(2)ꢁ and Cl2–Sn2–C31 98.5(2)ꢁ], Table 5.
The unit cell of compound 2 contains two independent
molecules, the bond lengths and angles in both molecules
do not differ beyond experimental error. The molecules
˚
hydrogen bond O2–H8 (2.38 A), another phenyl group in
Fig. 3. Racemic pair of compound 1 is shown as well as the hydrogen bonds between them.

1596
C. Camacho-Camacho et al. / Journal of Organometallic Chemistry 691 (2006) 1590–1597
3. Conclusion
Three new penta- and hexacoordinated tin compounds
(1–3) were obtained and characterized. The three com-
pounds present a weak dative Sn O bond that produces
hypervalent tin atoms. The weak coordination was mainly
established in the solid state, where the geometry implicates
the dative bond. Compound 1 has an hexacoordinate tin
atom, which is a stereogenic center. In the solid state it dis-
plays a racemic pair linked by strong hydrogen bonds. For
compounds 2 and 3 the tin atom is pentacoordinate. Com-
pound 3 has a long dative Sn O bond. Even if the 119Sn
chemical shift is not an argument for pentacoordination in
solution, the 1J(119Sn, 13C) of the tin atom and the ipso-car-
bon of the phenyl group is characteristic for pentacoordi-
nate tin and the Sn O is without question in the solid
state. All compounds present the distorted tbp geometry
with the carbonyl group in apical position and pointing
at the tin atom. Geometrical distortion is generated by
the ring tension. Compounds 2 and 3 showed a ‘‘Berry
exchange coordinate’’ geometries according to X-ray dif-
fraction analysis.
Fig. 5. Structure of compound 3 and the intramolecular hydrogen bonds.
equatorial is also aligned with the bond O1–Sn1 and a
˚
hydrogen bond is formed between H18 and O1 2.23 A,
Fig. 5.
For compound 1 the C1–O1 is more likely a double
bond [1.286(5) A], whereas the C2–O2 a single bond
4. Experimental
˚
˚
˚
˚
[1.418(5) A]. C1–C2 [1.432(6) A] and C2–C3 [1.419(6) A]
are delocalized bonds. For 3 where the O–Sn coordination
is weaker, the bond lengths values are C1–O1 1.238(9), C2–
4.1. General comments
All chemicals were reagent grade and were used without
further purification. Solvents were purified by usual meth-
ods. Melting point were obtained in Mel-Temp II appara-
tus and are uncorrected. IR (KBr, disc) were determined on
a Perkin–Elmer 16 FPC spectrometer. All 1H, 13C and
119Sn NMR spectra were run in CDCl3 on a Jeol Eclipse
400 spectrometer. d (ppm) being referenced to TMS for
˚
O2 1.346(7), C1–C2 1.441(1) and C2–C3 1.318(9) A.
Using the X-ray diffraction data we have calculated the
atomic charges of molecules 1–3 and the corresponding to
the ligand which are described in Table 7. The molecules
are neutral, the tin and C1 and C2 atoms have an impor-
tant positive charge, whereas the oxygen atoms bear the
negative charges. It is interesting that C3 does not share
the positive charge in an allylic delocalization.
1H and 13C and to Me4Sn for 119Sn. For H,13CꢀCOLOC
1
pulse sequence method used see Ref. [21,22]. Elemental
analyses were performed in Thermofinnigan Flash EA
1112 instrument. Atomic charges were calculated with the
MS Modeling program v3.2.0.0 from data of X-ray diffrac-
tion of the ketoenol ligand and compounds 1–3.
Table 7
Atomic charges calculated of the ketoenol ligand and the tin compounds
1–3
4.2. Syntheses
4.2.1. [(O–Sn)-Ethanol]-(3-methyl-2-oxo-cyclopentanen-1-
one-dichlorophenyltin) (1)
A mixture of 3-methyl-1,2-cyclopentanedione (6 mmol,
670 mg), SnPhCl3 (2 mmol, 604 mg) in ethanol (4 mL) is
stirred, at r.t. for 48 h. The white crystalline product was
filtered off. The tin compound was purified by recrystalliza-
tion from CH2Cl2/EtOH [3/1]. Yield: 754 mg, 89%. M.p.
102–104 ꢁC. IR (KBr) m (cmꢀ1): 3075 m, 1647 s, 1560 s,
1479 w, 1414 s, 1391 s, 1357 m, 1245 m, 1202 m, 1068 w,
1032 m, 871 w, 745 s, 699 m, 548 w, 521 w, 455 w. MS
(EI, 20 eV), m/z (%): 424 [M]+ꢀ, 377 (35), 301 (100), 266
(37). Anal. Calc. for C14H18O3Cl2Sn: C, 39.62; H, 4.27.
Found: C, 39.20; H, 4.09%.
Ligand
1
2
3
Sn
–
+1.514
ꢀ0.559
ꢀ0.467
+0.312
+0.343
ꢀ0.039
ꢀ0.345
ꢀ0.331
ꢀ0.470
+1.154
ꢀ0.609
ꢀ0.539
+0.325
+0.329
ꢀ0.013
ꢀ0.363
ꢀ0.299
ꢀ0.470
+1.115
ꢀ0.630
ꢀ0.548
+0.292
+0.327
ꢀ0.032
ꢀ0.382
ꢀ0.338
ꢀ0.474
+0.900
ꢀ0.613
ꢀ0.617
+0.312
+0.326
ꢀ0.015
ꢀ0.384
ꢀ0.326
ꢀ0.481
O1
O2
C1
C2
C3
C4
C5
C6
ꢀ0.416
ꢀ0.649
+0.434
+0.341
ꢀ0.045
ꢀ0.347
ꢀ0.293
ꢀ0.382

C. Camacho-Camacho et al. / Journal of Organometallic Chemistry 691 (2006) 1590–1597
1597
4.2.2. 3-Methyl-2-oxo-cyclopentanen-1-one-
chlorodiphenyltin (2)
Appendix A. Supplementary data
A
mixture of 3-methyl-1,2-cyclopentanedione (1)
Crystallographic data (excluding structure factors) for
compounds 1–3 have been deposited with the Cambridge
Crystallographic Data as supplementary Publications
Nos. CCDC-289015. Copies of the data can be obtained
free of charge on application to CCDC-289127 (1),
CCDC-289125 (2), CCDC-289126 (3), 12 Union Road,
Cambridge, CB2 1EZ, UK, fax: +44 1223 366 033, e-mail:
deposit@ccdc.ac.uk or on the web www: http://
www.ccdc.cam.ac.uk. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2005.12.036.
(4 mmol, 450 g), SnPh2Cl2 (2 mmol, 690 mg) and Et3N
(1 mmol) in ethanol (4 mL) was stirred at r.t. for 48 h. A
crystalline colorless product was filtered off and purified
by recrystallization from CH2Cl2/EtOH [3/1]. Yield:
750 mg, 89%. M.p. 116–118 ꢁC. IR (KBr) m (cmꢀ1): 3049
w, 2911 w, 1658 s, 1583 s, 1480 w, 1432 s, 1409 s, 1357 s,
1309 w, 1248 m, 1203 m, 1150 s, 1069 m, 996 w, 806 w,
743 s, 694 s, 542 w, 472 w, 498 w, 445 m. MS (EI,
20 eV), m/z (%): 419 [M]+ꢀ (3), 385 (18), 343 (100), 154
(54). Anal. Calc. for C18H17O2ClSn: C, 51.53; H, 4.09.
Found: C, 51.66; H, 4.14%.
References
4.2.3. 3-Methyl-2-oxo-cyclopentanen-1-one-triphenyltin (3)
A mixture of 3-methyl-1,2-cyclo-pentanedione (4 mmol,
450 mg), Ph3SnOH (4 mmol, 1.47 g) in toluene (8 mL) was
refluxed in a 50-mL flask equipped with a Dean Stark fun-
nel. After 5 h, the 50% of the initial solvent was distilled off
and the remaining solution was filtered. The solvent was
evaporated under vacuum and the crystalline colorless
product was purified by recrystallization from CH2Cl2/
EtOH [3/1]. Yield: 1.61 g, 88 %. M.p. 132–134 ꢁC. IR
(KBr) m (cmꢀ1): 3055 m, 2904 m, 1679 s, 1622 s, 1478 m,
1428 s, 1401 s, 1343 s, 1307 m, 1247 s, 1208 s, 1138 s,
1071 s, 995 m, 851 w, 811 w, 729 s, 697 s, 535 w, 441 s.
MS (EI, 20 eV), m/z (%): 385 (100), 351 (14), 231 (15).
Anal. Calc. for C24H22O2Sn: C, 62.51; H, 4.81. Found:
C, 62.78; H, 4.93%.
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˚
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´
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Acknowledgement
Financial support from Cinvestav, Conacyt and UAM-
X is acknowledged.
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