Structure of β-diketiminates and β-aminoketones made from anisidines or chloroanilines: Tin and lithium complexes

Article abstract of DOI:10.1515/mgmc-2012-0002

Three series of methoxyphenyl substituted β-diketiminate and β-enaminoketonate and chlorophenyl β-enaminoketonate ligands were prepared and studied by IR, ¹H and ¹³C NMR spectroscopy in solution and X-ray diffraction techniques in solid state. The crystal structures of [2-(MeO)C₆H₄]N=(H)-CCH(H)C[2-(MeO)C ₆H₄]NH.HCl,[2-(MeO)C₆H₄]N=(H)CCH(H) C[2-(MeO)C₆H₄]NH, [4-(MeO)C₆H ₄]N=(H)CCH-(H)C[4-(MeO)C₆H₄]NH, [4-ClC ₆H₄]N(H)(Me)CCH(Me)C=O, [2-(MeO)C₆H ₄]N=(Me)CCH(Me)C[2-(MeO)C₆H₄]NH and 7-methoxy-2,4-dimethylquinoline-toluenesulfonylacid adduct as ligands, their precursors and a byproduct isolated during the synthesis of [3-(MeO)C ₆H₄]N(H)(Me)CCH(Me)C=O were determined. One of the ligands the meta-methoxyphenyl substituted β-enaminone has been treated with n-butyllithium to give {[3-ClC₆H₄]N(Me)CCH(Me)C=O}Li which reveals tetrameric structure in the solid state. Further reactions of this lithium complex with tri- and diorganotin(IV) chlorides and hydride give appropriate organotin(IV) complexes with five coordinated tin atom. The direct reaction of bis(para-methoxyphenyl) substituted β-diketimine with Sn[N(SiMe₃)₂]₂ gives [4-(MeO)C ₆H₄]N=(H)CCH(H)C[4-(MeO)C₆H₄] NSnN(SiMe₃)₂. Structure of these complexes was evaluated by ¹H, ⁷Li and ¹¹⁹Sn NMR spectroscopy and X-ray diffraction analysis for two examples.

Full text of DOI:10.1515/mgmc-2012-0002

Main Group Met. Chem., 2012;35(1-2):13–27 © 2012 by Walter de Gruyter • Berlin • Boston. DOI 10.1515/mgmc-2012-0002
Structure of β-diketiminates and β-aminoketones made from
anisidines or chloroanilines: tin and lithium complexes
Roman Olejník1, Zdenˇka Padeˇlková1,
2010), as a single source precursor for material chemistry and
last but not least for kinetic stabilization of low valent metal
Michal Horácˇek2 and Aleš Ru˚žicˇka1,*
centers. These ligands can be applied as a bidentate monoan-
1 Department of General and Inorganic Chemistry, Faculty
ionic species with a delocalized π-electron system (Figure 1),
of Chemical Technology, University of Pardubice,
but another type of β-diketiminato complexes, for example,
Studentská 573, CZ-53210 Pardubice, Czech Republic
compounds with non-planar ligand central ring, three differ-
2 J. Heyrovský Institute of Physical Chemistry, Academy
ent types bimetallic complexes (Piesik et al., 2009), etc., are
of Sciences of the Czech Republic, v.v.i., Dolejškova 3,
known. These bonding modes with considerable diversity
CZ-18223 Prague 8, Czech Republic
are described in a review by Lappert (Bourget-Merle et al.,
2002). Recently, these complexes were successfully used for
stabilization of groups 13 (Kuhn et al., 1989; Gornitzka and
*Corresponding author
e-mail: ales.ruzicka@upce.cz
Stalke, 1994; Qian et al., 1998) and 14 (Ding et al., 2001a)
elements in low valence states. These six-membered hetero-
cycles are reviewed by Jones and Driess (Asay et al., 2011),
Abstract
showing high potential of β-diketiminato ligands with high
sterical demand to stabilize such a reactive species, for
example, Mg(I) (Bonyhady et al., 2010; Platts et al., 2011),
Three series of methoxyphenyl substituted β-diketiminate
and β-enaminoketonate and chlorophenyl β-enaminoketonate
1
ligands were prepared and studied by IR, H and 13C NMR
Si(II) (Meltzer et al., 2010; Xiong et al., 2010; Azhakar
spectroscopy in solution and X-ray diffraction techniques in
et al., 2011), Ge(I) (Woodul et al., 2011), Sn(I) (Choong et al.,
solid state. The crystal structures of [2-(MeO)C6H4]N=(H)-
CCH(H)C[2-(MeO)C6H4]NH.HCl, [2-(MeO)C6H4]N =
2012) and others.
β-Diketimines as precursors for alkaline metal
(H)CCH(H)C[2-(MeO)C6H4]NH, [4-(MeO)C6H4]N=(H)CCH-
(H)C[4-(MeO)C6H4]NH,[4-ClC6H4]N(H)(Me)CCH(Me)C=O,
[2-(MeO)C6H4]N=(Me)CCH(Me)C[2-(MeO)C6H4]NH and
7-methoxy-2,4-dimethylquinoline-toluenesulfonyl acid adduct
as ligands, their precursors and a byproduct isolated during the
synthesis of [3-(MeO)C6H4]N(H)(Me)CCH(Me)C=O were
determined. One of the ligands the meta-methoxyphenyl substi-
tuted β-enaminone has been treated with n-butyllithium to give
{[3-ClC6H4]N(Me)CCH(Me)C=O}Li which reveals tetrameric
structure in the solid state. Further reactions of this lithium com-
plex with tri- and diorganotin(IV) chlorides and hydride give
appropriate organotin(IV) complexes with five coordinated tin
atom. The direct reaction of bis(para-methoxyphenyl) substi-
tuted β-diketimine with Sn[N(SiMe3)2]2 gives [4-(MeO)C6H4]
N=(H)CCH(H)C[4-(MeO)C6H4]NSnN(SiMe3)2. Structure of
these complexes was evaluated by 1H, 7Li and 119Sn NMR spec-
troscopy and X-ray diffraction analysis for two examples.
β-diketiminato complexes are usually prepared by a conden-
sation reaction of diones (Carey et al., 2003; Chen et al., 2005)
or 1,1,3,3-tetraalkoxypropanes (Feldman et al., 1997; Cheng
et al., 2001; Stender et al., 2001; Jung and Kim, 2006) with
anilines (Scheme 1). Common byproducts in the reactions
of diones are β-enaminones which can also be deprotonated
(Kakaliou et al., 1999; Kao et al., 2008) by a strong base;
further reactivity of appropriate conjugated base with a metal
halide give another interesting class of main group metal
complexes (Dixit and Tandon, 1989; Singh et al., 2000).
In a series of both types of compounds, the majority of
examples contain a bulky phenyl (McGeachin, 1968) or naph-
thyl (Monillas et al., 2010) ligand. The complexes where an
aliphatic, trimethylsilyl or an adjacent coordination group is
employed are also known (Figure 2) (Bradley et al., 2008;
El-Zoghbi et al., 2010; Norman et al., 2010). The number of
papers on compounds where a donor group is directly bonded
to the phenyl ring is rather limited. The o-methoxy-substi-
tuted β-diketiminato complexes of Li (Carey et al., 2003), Y
(Shang et al., 2007), Lu (Liu et al., 2007; Shang et al., 2007),
Sc (Zhang et al., 2008) and Mg (Chisholm et al., 2005) are
described. Mg complex is useful for polymerization of rac-
lactides (Chisholm et al., 2005). For catalytic purposes, also
the o- and p-methoxy-substituted β-diketiminato complex of
zinc has been studied (Chisholm et al., 2005; Biyikal et al.,
2010).
Keywords: β-diketimines; β-enaminones; lithium; tin.
Introduction
The chemistry of metal complexes containing a β-diketiminate
as a spectator ligand is a phenomenon of approximately the
past two decades. These complexes are usually studied for
their possible catalytic applications (Dove et al., 2006;
Champouret et al., 2010) in a plethora of different organic
chemistry transformations (Cheng et al., 2000; Jana et al.,
In this paper, we concentrate on systematic IR, NMR and
solid state studies of two classes of methoxy-substituted
β-diketiminates and β-enaminoketonato ligands where the
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14 R. Olejník et al.
Figure 1 General description of (i) structure of β-diketimine (L) or β-enaminone (L1/2), (ii) resonance structures, (iii) β-diketiminate anion or
β-enaminoketonato ligand, and (iv) metal complexes.
majority of compounds were prepared much earlier (for ref-
erences see Table 1, Figure 3) and H NMR spectra of three
2-, 3- or 4-methoxy substituted β-enaminones, similar to stud-
ies reported earlier (Sanchez et al., 1997; Zhuo, 1997; Zhang
et al., 2006) (LCO1/2H , LC1M/2H and LCP1/2H ), in approximately
20% yield or 2-, 3- or 4-methoxy substituted β-diketimines
(LCOH , LCMH and LCPH ) (Carey et al., 2003; Chen et al.,
2005) in approximately 25% yield, respectively. The yield
of all compounds is independent of the amount of reactants,
p-toluenesulfonic acid as a catalyst, and the temperature of
reaction mixture. Extension of reaction time also did not affect
higher yields. The comparative series of chloro-substituted
β-enaminones, LCClO1/2H (Musker and Sakhawat, 1966) and
LCClP1/2H (Zhuo, 1997), were prepared by similar reactions
from chloro anilines where only the molar ratio of reactants
1:1 was used. The yield of these compounds is usually a half
of the yield of previous series.
1
compounds were measured in DMSO (hydrochlorides of
LHOH, LHMH and LHPH; see Table 1 and Figure 3). The com-
parison with appropriate chloro-substituted complexes will
also be performed. Two of these compounds studied, the
meta-methoxyphenyl substituted β-enaminone (LC1M/2H ) and
the para-methoxyphenyl-substituted β-diketimine (LHPH ),
were selected to be tested for complexation abilities.
Results and discussion
Synthesis
Althoughthepreparationofsomeofthecompoundsisreported
in the literature, modified and more detailed approaches are
described here. The reactions of 2,4-pentandione with two
or one molar equivalents of 2-, 3- or 4-methoxyaniline give
The reactions of 1,1,3,3-tetramethoxypropane with appro-
priate methoxyanilines give hydrochlorides of 2-, 3- or
4-methoxy substituted β-diketimines, LHOH.HCl (Richards
and Webb, 1976), LHMH.HCl and LHPH.HCl (Kikugawa
Scheme 1 General preparation of β-diketiminates a β-enaminones.
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Sn and Li complexes of β-diketiminates/β -aminoketones 15
Figure 2 Different types of β-diketimines.
and Sugimura, 1986), in moderate yields. Free β-diketimines
(LHOH , LHMH and LHPH ) are prepared by addition of sodium
carbonate or hydroxide.
The reaction of LCM1/2H with n-BuLi gives essential almost
quantitative yield (conversion considered by 1H NMR)
of LCM1/2Li at -78°C. The further reaction of LCM1/2Li with
organotin(IV) halides gives desired β-enaminoketonato
organotin(IV) complexes in high yield (Figure 4).
750 cm-1, =C-N bands at 1360–1250 cm-1 and C=C, C=N
stretching vibrations where the biggest values were deter-
mined in the LH ligand series. Based on this finding and
similarities in 1H and 13C NMR spectra, no IR spectra of com-
plexes were measured.
NMR studies
The ability of one of the ligands to coordinate tin(II) spe-
cies is demonstrated in the direct reaction of LHPH with the
Lappert’s stannylene (Harris and Lappert, 1974; Davidson
et al., 1976) by elimination of bis(trimethylsilyl)amine and
the subsequent formation of LHPSnN[Si(CH3)3]2 (Figure 5).
Although many of β-diketiminato tin(II) complexes are sub-
ject of various studies (Asay et al., 2011), no study pointed
to the non-substituted -NCHCHCHN- β-diketiminato ligand.
The stability of this compound towards moisture and air
gases is comparable to the reported complexes (Asay et al.,
2011).
All compounds prepared were subjected to multinuclear
NMR studies in solution. All 1H NMR spectra reveal one set
of signals attributable to the specific position of the hydrogen
atom in the molecule except for spectrum measured for LCM
H
where some signals are anisochronous, probably due to the
steric barrier of methoxy and methyl groups. The typical sig-
nal found at ∼12.4 ppm is attributed to NH hydrogen atom. In
hydrochlorides LHOH.HCl, LHMH.HCl and LHPH.HCl, there
is another signal found with the similar chemical shift value.
The next typical signals in 1H NMR spectra are those for CH
groups at approximately 5 ppm for free β-enaminoketones
and β-diketimines which are shifted to the lower field when
the free ligand is protonated by HCl. The methoxy groups
resonate in the range from 3.5 to 3.9 ppm. For all complexes
prepared (LCM1/2Li, LCM1/2Bu3Sn, LCM1/2Ph3Sn, LCM1/2Ph2SnCl
and LHPSnN[Si(CH3)3]2) , the signal at ∼12.5 ppm disap-
peared, and the rest of the signals slightly change their posi-
tions. Values for CH resonances slightly increased, and by
contrast the values for methoxy resonances decreased.
There are also a couple of specific signals in 13C NMR
spectra. The most significant signal is the resonance belong-
ing to the CH carbon in the center of the ligand which is found
in very narrow range from 94.4 to 99.6 ppm for both types of
ligands and lithium complexes, respectively. The presence of
methoxy groups as well as the methyl groups originated from
the starting acetylacetone in the case of LC type of ligands is
reflected in sharp resonances in specific regions (see Table 2
and experimental section), except the case of LCM1/2H , where
two discrete sets of signals were found similar to the 1H NMR
spectra of those compounds. Surprisingly, there are no obvi-
ous trends in 13C chemical shift values for free ligands as well
as their lithium complexes.
The IR spectra of all free ligands were measured to evalu-
ate the electronic structure of compounds and expected
changes in H-bonding. Surprisingly, only small changes were
observed for characteristic N-H deformation vibrations around
Table 1 Abbreviations used for prepared compounds (see Scheme 1).
Compound
R1
R4
o-
m-
p-
LCOH a
H
LCPH b
-CH3
-CH3
-CH3
-H
-H
-H
-H
-H
-H
-OCH3
–
–
-OCH3
–
–
-OCH3
–
–
–
–
–
LCM
-OCH3
–
–
-OCH3
–
–
-OCH3
–
–
-OCH3
–
–
LHOH .H C l c,x
LHMH .H C l x
LHPH .H C l c,d,x
LHOH c
LHM
H
-OCH3
–
LHPHc,d
-OCH3
LCO1/2H e
LCM1/2H f
LCP1/2H g
LCClO1/2H h
LCClP1/2H f
LCM1/2L i
-CH3
-CH3
-CH3
-CH3
-CH3
-CH3
-OCH3
–
–
-Cl
–
–
–
–
-OCH3
–
–
–
–
-OCH3
–
-Cl
–
7
The Li NMR spectra of LCM1/2H were recorded to prove
the structure differences in different types of solvents. The 7Li
NMR spectrum measured in toluene is rather different from
that measured in THF. It means that the structure of LCM1/2H in
THF solution probably split to monomeric blocks where the
lithium atom is coordinated by two THF molecules, as found
for four coordinated lithium amidinates previously (Chlupatý
-OCH3
b
c
aCarey et al. (2003), Gong and Ma (2008), Richards and Webb
d
e
(1976), (Kikugawa and Sugimura (1986), Sanchez et al. (1997),
fZhuo (1997), Zhang et al. (2006), Musker and Sakhawat (1966);
g
h
xhydrochlorides; L for β-diketimine, L1/2 for β-enaminone.
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16 R. Olejník et al.
Figure 3 Compounds used as ligands in this study.
et al., 2011). By contrast, the -3.22 ppm value found in the 7Li
NMR spectrum measured in toluene which can be attributed
to the tetrameric character of the compound in this solvent.
To evaluate the complexation ability of the ligand LCM1/2H ,
three organotin(IV) complexes were prepared by a conver-
sion of LCM1/2Li with organotin(IV) halide (Figure 4). From
the comparison of chemical shift values of chemical shifts in
119Sn NMR spectra of prepared complexes and starting chlo-
rides (20–120 ppm), it is seen that the coordination number
of the tin central atom increased from four to five. This is
caused by the bidentate coordination of LCM1/2H ligand via
nitrogen and oxygen atoms to the tin atom. The bidentate
coordination of LHP ligand to the tin atom is also expected
in LHPSnN[Si(CH3)3]2 where the δ (119Sn) is found at -164.1
ppm similar to β-diketiminato tin(II) amides reported by
Roesky (Jana et al., 2009) and Barrau (Akkari et al., 2001)
(-134.5 and -151.8 ppm).
anion prolongates the connection to the oxygen atom (Figure
1) of the water molecule, which is present in the unit cell.
The water molecule is further connected to the N2-H2 group
of adjacent molecule oriented perpendicularly to the original
molecule.
The product of the first deprotonation of LHOH.HCl is
compound LHOH with less complex molecular structure
(Figure 7). The π-electron delocalization detected in the
structure of previous compound (LHOH.HCl) is nearly miss-
ing in this molecule. To the best of our knowledge, there is
no crystal structure of free β-diketimine derived form 1,3-
unsubstituted -NCHCHCHN- reported to date. The main dif-
ferences are reflected in bond lengths C-C and C-N, where
the C9-C10 bond can be assigned to be a multiple bond but
the C8-C9 is the typical single bond with a limited degree of
π-electron delocalization. On the basis of C-N atoms sepa-
rations, one can predict that the N1 atom is of an imino type
and the N2 atom of an amino type. In addition, the degree
of planarity of the molecule is much lower than in LHO
H
Solid state studies
precursor, although the N2, C10 and C9 atoms nearly lie
in the plane defined by the phenyl ring C11-C16, the C8
and N1 atoms deviate from this plane significantly (0.314
and 0.454 Å), and the interplanar angle between both phenyl
ring planes is 35.21°. The intramolecular contact between
N2-H2 and N1 atoms is the only hydrogen bond found in
the molecule of LHOH.
During the course of these studies eight new crystal structures
of all types of studied compounds were determined by X-ray
crystallographic techniques. To evaluate the bonding situa-
tion on each ligand, the structure of the central core of each
compound is discussed.
The first compound was crystallized from the first step of
preparation of LHOH . The structure of LHOH.HCl is planar
with a zig-zag chain within the central fragment of the mol-
ecule. There is a high degree of delocalization of π-electrons
within the whole system. In comparison to other protonated
β-diketimine molecules (Kulpe and Schulz, 1981; Brownstein
et al., 1983; Kuhn et al., 2000), this particular hydrochloride
reveals rather short C-C and C-N distances (see Figure 6 cap-
tion). There is the extensive hydrogen bonding in the structure
of LHO.HCl. There are intramolecular hydrogen bonds NH...O
of both NH groups to the appropriate methoxy groups, while
the NH group of N1 atom is also connected to the chloride
The structure of the LHPH (Figure 8) is similar to the struc-
ture of LHOH with the exception of a slightly higher degree of
π-electron delocalization within the system which is reflected
in the shortening of the central core C-C bonds and elongation
of the C-N bonds in LHPH in comparison to LHOH which is
probably caused by the presence of an ortho effect in LHOH.
The phenyl rings are deviated with the same orientation from
the central NC3N plane by 26.67(12)°. There is only one intra-
molecular N1-H1a…N1d contact in the molecule of LHP
H
which is of similar magnitude as the appropriate hydrogen
bond in LHOH.
The only solid compound from the β-diketimine series
– LCClP1/2H (Sanchez et al., 1997; Zhuo, 1997; Zhang et
al., 2006) is prepared to compare this class of compounds
with related β-diketiminates. The centrosymmetric dimer
of LCClP1/2H (Figure 9) is formed via two intermolecular
hydrogen bridges in the solid state. The central NC3N planes
in the dimer are coplanar with the interplanar distance of
1.211(3) Å. The intermolecular H-bonding (N1-H1…O2)
is much weaker than the intramolecular bonding (N1-H1…
O1), which are in the magnitude comparable to analogous
Figure 4 Preparation of Sn(IV) derivatives of LCM
.
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Sn and Li complexes of β-diketiminates/β -aminoketones 17
Figure 5 Preparation of Sn(II) derivative of LHP
.
connections previously discussed LHOH and LHPH. Although
the planarity of the central NC3N core is nearly ideal, the
degree of delocalization within the system is rather low. The
major illustration of this fact are the interatomic distances
C7-N1 and C9-O1, where the first one is attributed to the
single bond, and by contrast the second one is a typical value
for C=O bond type. The interplanar angle of the phenyl ring
and the central NC3N plane is a bit higher [45.41(9)°] than
that found for LHPH.
The adduct of 7-methoxy-2,4-dimethylquinoline with
p-toluenesulfonic acid has been obtained as a minor byprod-
uct of catalyzed reaction of 2,4-pentandione with m-anisidine
(Figure 10). Both parts of adduct (Figure 11) are intercon-
nected by strong H-bridge O2-H…N1. All other interatomic
distances are in the typical range for analogous functional
groups previously reported in the literature (Mehta et al.,
2003) or the Cambridge Structural Data Base. To the best of
our knowledge, there is no molecular structure of 2,4-dicarba-
7-oxo substituted quinoline determined to date.
localization of a multiple bond between C9-N2 and C8-C7
atoms is taking place. The phenyl rings are twisted by
28.75(12)° for the ring connected by a hydrogen bridge
from O1 atom to the N1-H1 group and 48.67(13)° for the
second ring which reveals that there is no interaction of
this type. The intramolecular N1-H1…O1 connection is a
bit stronger than in previously discussed compounds with-
out methyl decoration of the central NC3N fragment (see
Figure 12 caption). The N1-H1...O1 connection is also
responsible for widening of C7-N1-C1 angle. In compari-
son to the LHOH and LHPH , the N1-N2 distance in LCOH is
shorter by 0.05 Å, which is in line with the literature values
for known β-diketimines (Crimmin et al., 2010; Monillas
et al., 2011).
Although the structure of LCO1/2Li (Figure 13) seems to be
heterocubane-like, the symmetry of this molecule is fairly
low. By contrast, the interatomic distances and angles of the
same type are of similar values, which allow us to discuss
the average values or the values for a virtual quarter of het-
erocubane moiety separately. The compound consists of the
rather deformed Li4O4 cube (Figure 14), where the oxygen
From the interatomic distances in the planar central
moiety of LCOH (Figure 12), it is clearly visible that the
Table 2 Selected NMR chemical shifts (ppm).
Compound
δ (1H(-NH))/δ(119Sn)/δ(7Li)
-N(H)CHCHCHN- or
-N(H)C(CH3)CHC(CH3)N-
-OCH3
δ(1H)
δ(13C)
δ(1H)
δ(13C)
LCOH a
12.73
12.54
12.57
12.21
4.94
5.13
4.87
5.17
5.17
5.05
5.12
5.05
5.09
97.9
97.4
96.4
95.9
95.8
94.4
97.6
97.3
96.8
98.5
98.0
99.6b/98.0c
–
3.79
3.65, 3.62
3.80
3.88
3.82
3.81
3.75
3.54
3.71
55.7
54.7, 54.3
55.5
55.4
55.0
55.7
55.4
54.6
LCMH a
LCPH a
LHOH a
LHMH a
12.48
12.22
12.29
12.35
12.26
12.40
12.42
-3.22b/1.40c
28.1
LHPH a
LCO1/2H a
LCM1/2H a
LCP1/2H a
55.3
–
LCClO1/2H a
LCClP1/2H a
LCM1/2L i
5.16
5.17
–
–
–
4.90b/4.73c
5.14
3.39b/3.67c
3.52
54.6b/55.2c
LCM1/2Bu3Snb
LCM1/2Ph3Snb
LCM1/2Ph2SnClb
LHPS n N [ S i ( C H 3)3]2
–
–
–
-119.8
-45.1
-164.1
5.85
5.61
4.97
–
–
96.6
3.27
3.43
3.72
c
55.7
aMeasured in CDCl3. bMeasured in toluene-d8. cMeasured in THF-d8.
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18 R. Olejník et al.
C2
C1d
N1d
C1
C4d
C4
N1
H1a
C5d
C6d
C5
C3d
C8d
C3
C8
01d
01
C6
C7
C7d
C9d
C9
Figure 8 Molecular structure of LHPH (ORTEPview, 50% probabil-
ity level). Hydrogen atoms are omitted for clarity (except for hydro-
gen atoms which are included in H-bonding). Selected interatomic
distances (Å) and angles (°): C3-N1 1.408(3); N1-C1 1.322(3);
C1-C2 1.390(3); C1-C1d 1.390(3); C1d-N1d 1.322(3); N1d-C3d
1.408(3); C3-N1-C1 121.784(19); N1-C1-C2 124.02(2); C1-C2-
C1d 124.50(3); C2-C1a-N1d 124.02(2); C1d-N1d-C3d 121.84(19);
N1-H1a…N1d 2.750(2).
Figure 6 Molecular structure of LHOH.HCl (ORTEP view, 50%
probability level). Hydrogen atoms are omitted for clarity (except for
hydrogen atoms which are included in H-bonding). Selected inter-
atomic distances (Å) and angles (°): C2-N1 1.411(5); N1-C8 1.323(6);
C8-C9 1.368(5); C9-C10 1.371(6); C10-N2 1.326(5); N2-C11
1.406(6); C2-N1-C8 125.09(4); N1-C8-C9 123.69(4); C8-C9-C10
118.34(4); C9-C10-N2 124.20(4); C10-N2-C11 125.32(4); N1-H1…
O1 2.601(5); N1-H1…Cl1 3.374(5); O3-H3…N2-H2 6.209(6);
N2-H2…O2 2.600(5).
between the ketimine central cores and phenyl rings are again
nearly perpendicular (∼87.5°). The elongation of the C10-O1
bond is caused by the bridging character of the C=O system
and an interaction of oxygen atom with two lithium atoms.
By contrast, the double bond character of C8-C9 interaction
remains unchanged.
The molecular structure of LHPSnN[Si(CH3)3]2 (Figure 15)
is a member of the family of tin(II) β-diketiminato complexes
which are of current interest (Asay et al., 2011). There is
approximately 40 crystal structures of tin(II) β-diketiminato
complexes reported to date, but none of them has unsubsti-
tuted CHCHCH central moiety. The central NC3N moiety in
LHPSnN[Si(CH3)3]2 has rather delocalized character similar
to the starting ligand LHPH. The phenyl rings are twisted from
this plane by 32.73(9)° and 49.36(12)°, respectively. The tin
atom is a bit above [0.195(4) Å] the plane defined by NC3N
atoms. In the case of β-diketiminato tin(II) alcoholate, an
atoms originated from the LCM1/2H ligand and interact with
three lithium atoms. These are further coordinated by nitro-
gen atoms from the essentially planar ligand similar to the
analogous ligand substituted by isopropyl fragment (Brehon
et al., 1997). The similarities in bonding of both ligands are
also seen from the interatomic distances and angles within
the ketimine fragments. In LCM1/2Li heterocubane core, the
ligands from neighboring lithium atoms are oriented in a
mutual perpendicular way (∼84°) and all interplanar angles
C9
C10
C8
N1
C16
C6
C11
C12
C5
C4
C1
N2
C15
C14
H2
C2
02
01
C3
C13
C17
C7
Figure 7 Molecular structure of LHOH (ORTEP view, 50% prob-
ability level). Hydrogen atoms are omitted for clarity (except for
hydrogen atoms which are included in H-bonding). Selected inter-
atomic distances (Å) and angles (°): C1-N1 1.413(3); N1-C8 1.291(3);
C8-C9 1.427(3); C9-C10 1.350(3); C10-N2 1.353(3); C1-N1-C8
118.73(18); N1-C8-C9 122.91(19); C8-C9-C10 124.39(19);
C9-C10-N2 124.30(2); C10-N2-C11 125.67(18); N2-H2…N1
2.728(2).
Figure 9 Molecular structure of LCClP1/2H (ORTEP view, 50%
probability level). Hydrogen atoms are omitted for clarity (except
for hydrogen atoms which are included in H-bonding). Selected
interatomic distances (Å) and angles (°): C4-N1 1.417(2); N1-C7
1.348(2); C7-C8 1.375(2); C8-C9 1.424(3); C9-O1 1.243(2);
C4-N1-C7127.55(15);N1-C7-C8121.44(15);C7-C8-C9124.82(15);
C8-C9-O1 123.74(17); N2-O1-N1 115.95(15); O1-N1-O2 64.05(15);
N1-H1…O1 2.705(2); N1-H1…O2 3.116(2).
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Sn and Li complexes of β-diketiminates/β -aminoketones 19
C18
C17
C8
C7
C9
C19
N1
02
H1
C6
N2
C12
C10
C11
C1
C2
Figure 10 Formation of 7-methoxy-2,4-dimethylquinoline.
C5
C15
C14
C13
01
C4
extreme deviation of the tin atom from that plane is found to
be 1.056(3) Å (Ferro et al., 2011). By contrast, this deviation
is nearly negligible in the case of tin(II) cation (Taylor et al.,
2011) or non-planar central ring of β-diketiminato tin(II) chlo-
ride (Woodul et al., 2010). The tin atom in LHPSnN[Si(CH3)3]2
is three coordinated with the coordination polyhedron of trig-
onal pyramid where the lone electron pair is virtually situ-
ated in an apical position. When the interatomic distances and
angles in LHPSnN[Si(CH3)3]2 are compared to the appropri-
ate parameters found for four known β-diketiminato tin(II)
amides, a conclusion is made that the Sn-N distances and
angles within the β-diketiminato tin(II) fragment are simi-
lar to the reported structures but Sn1-N3 [2.135(3) Å] dis-
tance and C9-Sn1-N3 angle [106.14(8)°] are much closer to
the values found for bulkier amides (Ding et al., 2001b; Jana
et al., 2009) than was found for less bulky dimethylamides
[2.038(4) Å, 88.82(9)° and 2.054(3) Å, 85.34(12)°] (Dove
et al., 2006).
C3
C16
Figure 12 Molecular structure of LCOH (ORTEP view, 50%
probability level). Hydrogen atoms are omitted for clarity (except
for hydrogen atoms which are included in H-bonding). Selected
interatomic distances (Å) and angles (°): C10-N2 1.415(3); N1-C7
1.363(2); C7-C8 1.372(3); C8-C9 1.435(3); C9-N2 1.301(2); N1-C1
1.406(2); C1-N1-C7 130.09(15); N1-C7-C8 120.02(16); C7-C8-C9
127.39(17); C8-C9-N2 120.35(17); C9-N2-C10 121.91(16);
N1-H1…N2 2.698(2); N1-H1…O1 2.605(2).
the differences in delocalization of π-electrons within the
NC3N system is made in the solid state. The highest degree
of this virtual parameter is observed for protonated LHO
.
HCl and ortho-substituted ligand LHOH and its complex
LHOSnN(SiMe3)2. By contrast, in the rest of the compounds
the conjugation – alternating of double and single bonds –
within this system is seen. This fact cannot be supported by
any NMR spectroscopy parameter observed in solution. The
LCM1/2H ([3-(MeO)C6H4]N(H)(Me)CCH(Me)C=O) can be
deprotonated by n-butyllithium and the respective lithium
salt is useful for preparation of organotin(IV) complexes
where the ligand is bidentately bonded to the tin atom. The
Conclusion
Within the series of studied methoxyphenyl- or chloro-
substituted β-diketiminate and β- enaminoketonate ligands
and its lithium and tin complexes, the conclusion about
elimination of HN(SiMe3)2 is taking place when the LHO
H
is added to the Lappert’s stannylene in equimolar ratio, thus
forming the β-diketiminato complex LHOSnN(SiMe3)2. This
approach can be a useful method in future preparation of
similar compounds.
C10
01
C1
C7
C9
04a
S1a
C2
N1
C18a
C17a
C16a
C8
Experimental
C19a
C3
C13a
General methods
03a
02a
C6
C15a
C14a
H1
NMR spectroscopy NMR spectra were recorded from solutions
in CDCl3, THF-d8, toluene-d8 or DMSO-d6 on a Bruker Avance 500
spectrometer (Bruker Biospin, Rheinstetten, Germany) (equipped
C12
C4
C5
1
C11
with Z-gradient 5 mm probe) at frequencies for H (500.13 MHz),
13C{1H} (125.76 MHz), 119Sn{1H} (186.50 MHz) and 7Li (194.4
MHz) at 295 K. In the case of air sensitive complexes were deu-
terated solvents distilled, degassed and then stored over K-mirror
under an argon atmosphere. Solutions were obtained by dissolving
approximately 30 mg of each compound in approximately 0.5 ml
of deuterated solvents. Values of 1H chemical shifts were calibrated
to internal standard – tetramethylsilane [δ(1H)=0.00] or to residual
signals of CDCl3 [δ(1H)=7.27], THF [δ(1H)=3.58 or 1.73], toluene-
d8 [δ(1H)=2.08] or DMSO-d6 [δ(1H)=2.50]. Values of 13C chemi-
cal shifts were calibrated to signals of CDCl3 [δ(13C)=77.16], THF
Figure 11 Molecular structure of 7-methoxy-2,4-dimethylquin-
olinium 4-methylbenzenesulfonate (ORTEP view, 50% probability
level). Hydrogen atoms are omitted for clarity (except for hydro-
gen atoms which are included in H-bonding). Selected interatomic
distances (Å) and angles (°): C3-N1 1.377(3); N1-C4 1.334(3);
C4-C5 1.397(3); C5-C6 1.377(3); C6-C7 1.427(3); C7-C3 1.409(3);
C3-N1-C4 122.80(18); N1-C4-C5 119.28(2); C4-C5-C6 121.56(2);
C5-C6-C7 118.31(19); C6-C7-C3 119.03(2); C7-C3-N1 119.01(19);
N1…O2a-H 2.720(3).
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20 R. Olejník et al.
Figure 13 Molecular structure of LCM1/2Li (ORTEP view, 60% probability level). Hydrogen atoms are omitted for clarity. Selected inter-
atomic distances (Å) and angles (°): C1-N1 1.423(5); N1-C8 1.298(5); C8-C9 1.437(6); C9-C10 1.363(6); C10-O1 1.304(4); C1-N1-C8
120.20(3); N1-C8-C9 122.40(4); C8-C9-C10 128.80(4); C9-C10-O1 124.90(3).
[δ(13C)=67.21 or 25.31], toluene-d8 [δ(13C)=20.43] and DMSO-d6
Elemental analyses The compositional analyses were determined
7
[δ(13C) =39.52]. The Li NMR spectra were calibrated to external
(under an inert atmosphere of argon if necessary) on the automatic
analyzer EA 1108 by FISONS Instruments (Parkton, UK).
1 m LiCl in D2O [δ(7Li)=0.0 ppm]. 119Sn chemical shift values are
referred to external neat tetramethylstannane [δ(119Sn)=0.0 ppm].
IR spectroscopy IR spectra of samples in KBr pellets were
measured in an air-protecting cuvette on a Nicolet Avatar FT
IR spectrometer (Thermo Electron Scientific Instruments LLC,
Fitchburg, WI, USA) in the range 400–4000 cm-1. KBr pellets
were prepared in a glovebox Labmaster 130 (mBraun) under puri-
fied nitrogen. IR spectra of neat liquid samples were measured
among KBr slides on a Nicolet Avatar FT IR spectrometer in the
range 400–4000 cm-1.
Positive chemical shift values denote shifts to the higher frequencies
relative to the standards. 119Sn NMR spectra were measured using the
inverse gated-decoupling mode. All 13C NMR spectra were measured
using the standard proton-decoupled experiment and CH and CH3 vs.
C and CH2 were differentiated by the standard APT method (Patt and
Shoolery, 1982).
Figure 15 Molecular structure of LHPSnN[Si(CH3)3]2 (ORTEP
view, 30% probability level). Hydrogen atoms are omitted for clarity.
Selected interatomic distances (Å) and angles (°): C11-N2 1.428(5);
N2-C10 1.322(4); C10-C9 1.387(6); C9-C8 1.389(5); C8-N1
1.320(4); N1-C1 1.427(5); N2-Sn1 2.226(3); N1-Sn1 2.221(3);
Sn1-N3 2.135(3); Sn1-Si1 3.228(10); C11-N2-C10 118.6(3);
N2-C10-C9 128.3(3); C10-C9-C8 127.03(3); C9-C8-N1 127.01(4);
C8-N1-C1 118.1(3); N2-Sn1-N1 84.82(10); N2-Sn1-N3 100.70(10);
N1-Sn1-N3 97.96(10); C9-Sn1-N3 106.14(9).
Figure 14 Detail of deformed heterocubane of molecular struc-
ture of LCM1/2Li (ORTEP view, 60% probability level). Some of
the ligands and hydrogen atoms are omitted for clarity. Selected
interatomic distances (Å) and angles (°): Li1-O1 1.922(6); Li1-O4
1.963(6); Li1-O3 1.963(6); Li1-N1 1.963(6); O4-Li1-O1 93.50(3);
O4-Li1-O3 94.10(3); O4-Li1-N1 140.10(3); O1-Li1-N1 96.40(3).
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Sn and Li complexes of β-diketiminates/β -aminoketones 21
Crystallography The X-ray data obtained from colorless crys-
tals for all compounds were acquired at 150 K using an Oxford
Cryostream low-temperature device on a Nonius KappaCCD dif-
fractometer (Bruker-Nonius, Delft, The Netherlands) with MoKα
radiation (λ=0.71073 Å), a graphite monochromator, and in the Φ
and χ scan mode. Data reductions were performed with DENZO-
SMN (Otwinowski and Minor, 1997). The absorption was corrected
by integration methods (Coppens, 1970). Structures were solved by
direct methods (Sir92) (Altomare et al., 1993) and refined by full
matrix least-square based on F2 (SHELXL97) (Sheldrick, 1997).
Hydrogen atoms were mostly localized on a difference Fourier map,
but to ensure uniformity of the treatment of the crystal, all hydro-
gen atoms were recalculated into idealized positions (riding model)
and assigned temperature factors Hiso(H)=1.2 Ueq (pivot atom) or of
1.5 Ueq for the methyl moiety with C-H=0.96, 0.97, 0.98 and
0.93 Å for methyl, methylene, methine and hydrogen atoms in aro-
matic rings, or multiply bounded C-H groups, respectively. Protons
on N and O were located on the Fourier difference map. The water
molecule in the structure of LHO.HCl is disordered into two positions
and is treated by standard constrains and restrains in the SHELXL97
program (Sheldrick, 1997).
Kim, 2006). Reaction mixture was heated to 70°C. Orange-red pre-
cipitate was formed immediately. After filtration the precipitate was
washed twice with petrolether (30 ml).
Compounds LHOH.HCl and LHPH.HCl can be prepared by reac-
tion of concentrated HCl (5 ml, 36%, 0.06 mol), which was added
through a reflux cooler to methoxyaniline (0.04 mol) in a round bot-
tomed flask equipped with a condenser. After a short time, 1,1,3,3-
tetramethoxypropane (3.3 ml, 0.02 mol) was added and the reaction
mixture was heated to reflux for 11 h (Richards and Webb, 1976;
Kikugawa and Sugimura, 1986). After cooling to room temperature
dark red product was filtered, washed with petrolether (20 ml) and
recrystallized from ethanol.
The second alternative syntheses of ligands LHOH.HCl and LHPH.
HCl is reaction 1,1,3,3-tetramethoxypropane (3.3 ml, 0.02 mol),
which was added to the solution of HCl (5 ml, 36%, 0.06 mol) in
ethanol (40 ml). The reaction mixture was heated to reflux for 5 h.
Red precipitate was filtered, washed with hexane (30 ml) and recrys-
tallized from ethanol.
General procedure of preparation of LHOH, LHMH and LHPH from
their hydrochlorides Protonated ligands LH.HCl were dissolved
in CHCl3 (ca. 30 ml) or in a mixture of CH2Cl2 and Et2O (5:1, ca.
40 ml). The solution was extracted with water solution of NaOH
(0.2 m, ca. 20 ml) or Na2CO3 (20%, ca. 40 ml). Organic phase was
separated, dried with anhydrous Na2SO4 and filtered. Pure products
were obtained after evaporation of solvents in vacuo.
Crystallographic data (Table 3) for structural analysis have been
deposited with the Cambridge Crystallographic Data Center. Copies
of this information may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EY, UK (fax: +44-1223-
336033; e-mail: deposit@ccdc.cam.ac.uk or www: http:// www.ccdc.
cam.ac.uk). CCDC deposition numbers 860307–860314.
General procedure of preparation of Sn(IV) complexes from
LCM1/2Li All syntheses were performed using standard Schlenk tech-
niques under inert argon atmosphere. Sn(IV) compounds were sus-
pended in dried Et2O (15 ml) and cooled to -78°C. Then, LCM1/2Li in
Et2O (15 ml) was added. The reaction mixture was slowly warmed to
room temperature and LiCl formed during the warming was filtered.
Syntheses
General procedures Preparation of LCM1/2Li, LCM1/2Bu3Sn,
LCM1/2Ph3Sn, LCM1/2Ph2SnCl and LHPSnN[Si(Me)3]2 complexes
was performed using standard Schlenk techniques under inert at-
mosphere of argon. Solvents and reactants were purchased from
commercial sources. Solvents (Et2O, hexane) were distilled over
K/Na alloy, degassed and then stored over a K-mirror under argon
atmosphere.
LCOH; N,N′-pent-2-en-2-yl-4-ylidene-bis(2-methoxyanyline) (Carey
et al., 2003) Yellow solid. Yield 12.5 g (17%). Elemental anal. (%)
for C19H22N2O2: C, 73.52; H, 7.14; N, 9.03. Found: C, 73.4; H, 7.0; N,
1
9.0. Melting point 123–125°C. H NMR CDCl3 (500 MHz, CDCl3,
298 K): δ 12.73 (s, 1H, NH), 7.11 (d, JH-H=8.00 Hz, 4H, Ar), 6.92–
6.88 (m, 4H, Ar), 4.94 (s, 1H, NHC(CH3)CHC(CH3)N), 3.79 (s, 6H,
OCH3), 1.99 (s, 6H, NHC(CH3)CHC(CH3)N). 13C NMR (125 MHz,
CDCl3, 298 K): δ 159.9 (C=N), 151.2 (C-NH, aromatic C), 135.3
(C-OCH3, aromatic C), 123.6, 123.0, 120.5 and 111.5 (aromatic CH),
97.9 (NHC(CH3)CHC(CH3)N), 55.7 (OCH3), 21.2 (NHC(CH3)-
CHC(CH3)N). IR (KBr, cm-1): 3068–3004 (m, CaromH), 2971–2938
(m, CH3), 2833 (m, OCH3), 1630 (s), 1594 (m), 1557 (vs), 1480 (m),
1382 (m), 1286 (s), 1231 (s), 1189 (m, C-Nstretching), 1118 (m), 1026
(s), 746 (s, CH out of plane bending, o-substituted benzenes).
General procedure of preparation of LCO
H 2,4-Pentandione (25
ml, 0.24 mol), 2-methoxyaniline (60 ml, 0.53 mol) and toluene (ca.
200 ml) were mixed in a 500 ml round bottomed flask (Carey et
al., 2003). A catalytic amount of p-toluensulfonic acid (30 mg, 0.17
mmol) was added. Resultant yellow-brown mixture was stirred and
heated to reflux for 5 h. The water (ca. 8 ml) formed by the reaction
was continually distilled off using a Dean-Stark apparatus. The ma-
jority of toluene (150 ml) was then removed off by distillation and
the residue was cooled slowly to room temperature and then stored
in a freezer (-28°C) for 5 h. Yellow-brown solid product was filtered,
washed twice with petrolether (20 ml) and recrystallized twice from
chloroform.
LCO1/2H; 4-[(2-methoxyphenyl)amino]pent-3-en-2-one (Sanchez
et al., 1997) In a slight modification of the literature procedure
(Carey et al., 2003; Chen et al., 2005), 2,4-pentandione (25 ml, 0.24
mol) and o-anisidine (27 ml, 0.24 mol) reacted equimolar. The prod-
uct was collected as pale yellow oil at 130–137°C (pressure 266 Pa).
Yield 25.5 g (52%). Elemental anal. (%) for C12H15NO2: C, 70.22; H,
General procedure of preparation of LCO1/2H, LCMH, LCM1/2H,
LCPH, LCP1/2H, LCClO1/2H and LCClP1/2H In a slight modification of
the literature procedure (Carey et al., 2003; Chen et al., 2005), all
toluene was distilled off from the reaction mixture. The residue was
vacuum-distilled. Two major fractions were collected: the first was
β-aminoketone and the second desired β-diketiminate.
1
7.37; N, 6.82. Found: C, 70.2; H, 7.4; N, 6.7. H NMR (500 MHz,
CDCl3, 298 K): δ 12.29 (s, 1H, NH), 7.03 (t, JH-H=7.75 Hz, 2H, Ar),
6.82 (d, JH-H=9.60 Hz, 2H, Ar), 5.12 (s, 1H, NHC(CH3)CHC(CH3)-
O), 3.75 (s, 3H, OCH3), 2.01 (s, 3H, NHC(CH3)CHC(CH3)O), 1.90
(s, 3H, NHC(CH3)CHC(CH3)O). 13C NMR (125 MHz, CDCl3, 298
K): δ 195.4 (C=O), 160.0 (C-N), 152.4 (C-NH, aromatic C), 127.7
(C-OCH3 aromatic C), 125.9, 124.6, 120.0 and 111.0 (aromatic CH),
97.6 (NHC(CH3)CHC(CH3)O), 55.4 (OCH3), 28.9 (NHC(CH3)-
CHC(CH3)O), 19.7 (NHC(CH3)CHC(CH3)O). IR (neat, cm-1):
General procedure of preparation of LHOH.HCl, LHMH.HCl and
LHPH.HCl A mixture of HCl (10 ml, 36%, 0.12 mol) and methoxya-
niline (0.13 mol) in distilled water (150 ml) was added dropwise to
the solution of 1,1,3,3-tetramethoxypropane (10 ml, 0.06 mol) and
HCl (8 ml, 36%, 0.094 mol) in distilled water (100 ml) (Jung and
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22 R. Olejník et al.
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Sn and Li complexes of β-diketiminates/β -aminoketones 23
3068–3001 (m, CaromH), 2963–2914 (m, CH3), 2837 (m, OCH3),
1616 (vs, C=Ostretching), 1571 (vs, C=Ostretching), 1482 (m), 1355 (m),
1279 (s), 1248 (m), 1174 (m, C-Nstretching), 1117 (m), 1027 (s), 750 (s,
CH out of plane bending, o-substituted benzenes).
NH), 6.96 (d, JH-H=8.69 Hz, 2H, Ar), 6.75 (d, JH-H=8.80 Hz, 2H, Ar),
5.09 (s, 1H, NHC(CH3)CHC(CH3)O), 3.71 (s, 3H, OCH3), 2.01 (s,
3H, NHC(CH3)CHC(CH3)O), 1.83 (s, 3H, NHC(CH3)CHC(CH3)O).
13C NMR (125 MHz, CDCl3, 298 K): δ 195.6 (C=O), 168.5 (C-N),
161.2 (C-NH, aromatic C), 131.3 (C-OCH3 aromatic C), 126.5 and
114.4 (aromatic CH), 96.8 (NHC(CH3)CHC(CH3)O), 55.3 (OCH3),
28.9 (NHC(CH3)CHC(CH3)O), 19.5 (NHC(CH3)CHC(CH3)O). IR
(neat, cm-1): 3066–3000 (w, CaromH), 2999–2910 (m, CH3), 2836 (m,
OCH3), 1614 (vs, C=Ostretching), 1570 (s, C=Ostretching), 1516 (vs), 1279
(m), 1248 (vs), 1187 (m, C-Nstretching), 1034 (m), 842 (s, CH out of
plane bending, p-substituted benzenes), 745 (w, NHdef).
LCMH; N,N′-pent-2-en-2-yl-4-ylidene-bis(3-methoxyanyline) Yellow
orange oil. Collected at 130–133°C (pressure 266 Pa). Yield 20.0 g
(27%). Elemental anal. (%) for C19H22N2O2: C, 73.52; H, 7.14; N, 9.03.
Found: C, 73.4; H, 7.1; N, 9.0. 1H NMR (500 MHz, CDCl3, 298 K):
δ 12.54 (s, 1H, NH), 7.14 (t, JH-H=8.02 Hz, 1H, Ar), 6.96 (t, JH-H=7.97
Hz, 1H, Ar), 6.66 (d, JH-H=8.35 Hz, 1H, Ar), 6.62 (d, JH-H=7.88 Hz,
1H, Ar), 6.59 (s, 1H, Ar), 6.23 (d, JH-H=8.16 Hz, 1H, Ar), 6.20 (d,
JH-H=7.90 Hz, 1H, Ar), 6.16 (s, 1H, Ar), 5.13 (s, 1H, NHC(CH3)-
CHC(CH3)N), 3.65 (s, 3H, OCH3), 3.62 (s, 3H, OCH3), 2.05 (s, 3H,
NHC(CH3)CHC(CH3)N), 1.92 (s, 3H, NHC(CH3)CHC(CH3)N). 13C
NMR (125 MHz, CDCl3, 298 K): δ 160.3 (C=N), 148.1 (C-NH aro-
matic C), 139.4 (C-OCH3, aromatic C), 109.7, 107.7, 103.0 and 100.3
(aromatic CH), 97.4 (NHC(CH3)CHC(CH3)N), 54.7 (OCH3), 54.3
(OCH3), 19.3 (NHC(CH3)CHC(CH3)N). IR (neat, cm-1): 3062–3008
(m, CaromH), 2999–2945 (m, CH3), 2835 (m, OCH3), 1621 (vs), 1600
(vs), 1573 (vs), 1496 (m), 1357 (m), 1287 (s), 1207 (m, C-Nstretching),
1158 (s), 1041 (m), 957 (m), 846 (m), 762 (m, NHdef), 689 (m, CH out
of plane bending, m-substituted benzenes).
LHOH.HCl; 2-methoxy-N-{3-[(2-methoxyphenyl)amino]prop-2-en-1-
ylidene}anilinium chloride (Richards and Webb, 1976) The prod-
uct was collected as red solid. Yield 11.5 g (65%). Elemental anal.
(%) for C17H19ClN2O2: C, 64.05; H, 6.01; Cl, 11.12; N, 8.79. Found:
C, 64.15; H, 6.0; Cl, 11.0; N, 8.8. Melting point 125–133°C. 1H NMR
(500 MHz, DMSO-d6, 298 K): δ 11.85 (d, JH-H=13.85 Hz, 2H, NH),
8.93 (t, JH-H=12.01 Hz, 2H, NHCHCHCHNH), 7.56 (d, JH-H=7.87
Hz, 2H, Ar), 7.27 (t, JH-H=7.57 Hz, 2H, Ar), 7.18 (d, JH-H=8.23 Hz,
2H, Ar), 7.07 (t, JH-H=7.61 Hz, 2H, Ar), 6.74 (t, JH-H=11.64 Hz,
1H, NHCHCHCHNH), 3.93 (s, 6H, OCH3). 13C NMR (125 MHz,
DMSO-d6, 298 K): δ 161.7 (C=N), 151.0 (C-NH, aromatic C), 130.3
(C-OCH3, aromatic C), 128.8, 122.2, 119.7 and 113.5 (aromatic CH),
100.7 (NHCHCHCHN), 57.1 (OCH3).
LCM1/2H;
4-[(3-methoxyphenyl)amino]pent-3-en-2-one
(Zhuo,
1997) The product was yellow oil and was collected as secondary
product at 115–119°C (pressure 266 Pa). Yield 15.0 g. Elemental
anal. (%) for C12H15NO2: C, 70.22; H, 7.37; N, 6.82. Found: C,
LHMH.HCl; 3-methoxy-N-{3-[(3-methoxyphenyl)amino]prop-2-en-1-
ylidene}anilinium chloride The product was collected as red solid.
Yield 10.6 g (60%). Elemental anal. (%) for C17H19ClN2O2: C, 64.05;
H, 6.01; Cl, 11.12; N, 8.79. Found: C, 64.2; H, 6.1; Cl, 11.0; N, 8.9.
1
70.1; H, 7.2; N, 6.8. H NMR (500 MHz, CDCl3, 298 K): δ 12.35
(s, 1H, NH), 6.99 (t, JH-H=8.04 Hz, 1H, Ar), 6.50 (d, JH-H=8.31 Hz,
1H, Ar), 6.47 (d, JH-H=7.85 Hz, 1H, Ar), 6.42 (s, 1H, Ar), 5.05 (s,
1H, NHC(CH3)CHC(CH3)O), 3.54 (s, 3H, OCH3), 1.88 (s, 3H,
NHC(CH3)CHC(CH3)O), 1.79 (s, 3H, NHC(CH3)CHC(CH3)O). 13C
NMR (125 MHz, CDCl3, 298 K): δ 195.4 (C=O), 159.7 (C-N), 159.4
(C-NH, aromatic C), 139.4 (C-OCH3 aromatic C), 129.3, 116.1,
111.3 and 110.3 (aromatic CH), 97.3 (NHC(CH3)CHC(CH3)O), 54.6
(OCH3),30.2(NHC(CH3)CHC(CH3)O),19.3(NHC(CH3)CHC(CH3)-
O). IR (neat, cm-1): 3064–3000 (m, CaromH), 2961–2903 (m, CH3),
2836 (m, OCH3), 1600 (vs, C=Ostretching), 1576 (vs, C=Ostretching), 1494
(m), 1320 (m), 1281 (s), 1188 (m, C-Nstretching), 1157 (s), 1048 (m),
957 (m), 851 (m), 757 (m, NHdef), 693 (m, CH out of plane bending,
m-substituted benzenes).
1
Melting point 125–135°C. H NMR (500 MHz, DMSO-d6, 298 K):
δ 12.64 (d, JH-H=13.90 Hz, 2H, NH), 9.03 (t, JH-H=13.13 Hz, 2H,
NHCHCHCHNH), 7.35 (t, JH-H=8.05 Hz, 2H, Ar), 7.07 (s, 2H, Ar),
7.02 (d, JH-H=7.85 Hz, 2H, Ar), 6.82 (d, JH-H=8.15 Hz, 2H, Ar), 6.49
(t, JH-H=11.43 Hz, 1H, NHCHCHCHNH), 3.81 (s, 6H, OCH3). 13C
NMR (125 MHz, DMSO-d6, 298 K): δ 161.4 (C=N), 159.5 (C-NH2,
aromatic C), 140.8 (C-OCH3, aromatic C), 131.8, 112.6, 110.9 and
104.0 (aromatic C), 99.6 (NHCHCHCHN), 56.5 (OCH3).
LHPH.HCl; 4-methoxy-N-{3-[(4-methoxyphenyl)amino]prop-2-en-1-
ylidene}anilinium chloride (Richards and Webb, 1976; Kikugawa
and Sugimura, 1986) The product was collected as red solid. Yield
8.8 g (50%). Elemental anal. (%) for C17H19ClN2O2: C, 64.05; H,
6.01; Cl, 11.12; N, 8.79. Found: C, 64.1; H, 6.1; Cl, 11.0; N, 8.8.
LCPH; N,N′-pent-2-en-2-yl-4-ylidene-bis(4-methoxyanyline) (Gong
and Ma, 2008) The product was collected as distillation residue and
recrystallized from chloroform. The product was dark viscous oil.
Yield 10.0 g (13%). Elemental anal. (%) for C19H22N2O2: C, 73.52;
H, 7.14; N, 9.03. Found: C, 73.6; H, 7.1; N, 9.0. 1H NMR (500 MHz,
CDCl3, 298 K): δ 12.57 (br s, 1H, NH), 7.13 (d, JH-H=7.58 Hz, 4H,Ar),
6.87 (d, JH-H=8.69 Hz, 4H, Ar), 4.87 (s, 1H, NHC(CH3)CHC(CH3)N),
3.80 (s, 6H, OCH3), 1.99 (s, 6H, NHC(CH3)CHC(CH3)N). 13C NMR
(125 MHz, CDCl3, 298 K): δ 160.2 (C=N), 156.0 (C-NH aromatic
C), 138.9 (C-OCH3, aromatic C), 124.2 and 114.2 (aromatic CH),
96.4 (NHC(CH3)CHC(CH3)N), 55.5 (OCH3), 20.7 (NHC(CH3)-
CHC(CH3)N). IR (KBr, cm-1): 3034–3001 (w, CaromH), 2957–2901
(m, CH3), 2833 (m, OCH3), 1623 (s), 1542 (s), 1501 (vs), 1276 (m),
1243 (vs), 1187 (m, C-Nstretching), 1034 (m), 839 (s, CH out of plane
bending, p-substituted benzenes), 770 (w, NHdef).
1
Melting point 128–133°C. H NMR (500 MHz, DMSO-d6, 298 K):
δ 12.47 (d, JH-H=14.10 Hz, 2H, NH), 8.81 (t, JH-H=11.70 Hz, 2H,
NHCHCHCHNH), 7.39 (d, JH-H=8.99 Hz, 4H, Ar), 7.00 (d, JH-H=8.92
Hz, 4H, Ar), 6.41 (t, JH-H=11.56 Hz, 1H, NHCHCHCHNH), 3.76 (s,
6H, OCH3). 13C NMR (125 MHz, DMSO-d6, 298 K): δ 158.2 (C=N),
133.1 (C-NH2, aromatic C), 125.5 (C-OCH3, aromatic C), 119.7 and
116.0 (aromatic C), 98.7 (NHCHCHCHN), 56.4 (OCH3).
LHOH; N,N′-prop-1-en-1-yl-3-ylidene-bis(2-methoxyaniline) (Richards
and Webb, 1976) The product was collected as yellow solid. Yield 3.5
g (55% overall, calculated on 2,4-pentandione). Elemental anal. (%)
for C17H18N2O2: C, 72.32; H, 6.43; N, 9.92. Found: C, 72.3; H, 6.4; N,
1
9.9. Melting point 120–122°C. H NMR (500 MHz, CDCl3, 298 K):
δ 12.21 (br s, 1H, NH), 7.75 (d, JH-H=5.05 Hz, 2H, NHCHCHCHN),
7.05–7.01 (m, 4H, Ar), 6.96–6.91 (m, 4H, Ar), 5.17 (t, JH-H=6.00 Hz,
1H, NHCHCHCHNH), 3.88 (s, 6H, OCH3). 13C NMR (125 MHz,
CDCl3, 298 K): δ 150.0 (C=N), 148.1 (C-NH2, aromatic C), 136.6
(C-OCH3, aromatic C), 123.3, 120.9, 114.9 and 110.8 (aromatic C),
95.9 (NHCHCHCHN), 55.4 (OCH3). IR (KBr, cm-1): 3084–3014 (m,
CaromH), 2958–2914 (m, CH3), 2837 (m, OCH3), 1631 (vs), 1594 (m),
LCP1/2H; 4-[(4-methoxyphenyl)amino]pent-3-en-2-one (Zhang et al.,
2006) The product was yellow oil and was collected as secondary
product at 135–145°C (pressure 266 Pa). Yield 25.0 g. Elemental
anal. (%) for C12H15NO2: C, 70.22; H, 7.37; N, 6.82. Found: C, 70.2;
H, 7.3; N, 6.8. 1H NMR (500 MHz, CDCl3, 298 K): δ 12.26 (s, 1H,
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24 R. Olejník et al.
1542 (vs), 1462 (m), 1386 (m), 1279 (s), 1248 (s), 1178 (m, C-Nstretching),
1118 (m), 1029 (s), 750 (s, CH out of plane bending, o-substituted
benzenes).
(NHC(CH3)CHC(CH3)O), 30.0 (NHC(CH3)CHC(CH3)O), 19.9
(NHC(CH3)CHC(CH3)O). IR (KBr, cm-1): 3186–3023 (m, CaromH),
2933–2901 (w, CH3), 2874 (w, OCH3), 1600 (s), 1564 (s), 1533 (vs),
1489 (vs), 1310 (s), 1290 (m), 1220 (m), 1164 (s), 1033 (m), 1011
(m), 815 (m, CH out of plane bending, p-substituted benzenes), 681
(s, C-C chlorine compounds), 569 (m).
LHMH; N,N′-prop-1-en-1-yl-3-ylidene-bis(3-methoxyaniline) The
product was collected as red viscous oil. Yield 2.3 g (51% overall,
calculated on 2,4-pentandione). Elemental anal. (%) for C17H18N2O2:
C, 72.32; H, 6.43; N, 9.92. Found: C, 72.3; H, 6.5; N, 9.9. 1H NMR
(500 MHz, CDCl3, 298 K): δ 12.48 (br s, 1H, NH), 7.69 (d, JH-H=6.80
Hz, 2H, NHCHCHCHN), 7.24 (t, JH-H=8.05 Hz, 2H, Ar), 6.69 (d,
JH-H=8.13 Hz, 2H, Ar), 6.65–6.62 (m, 4H, Ar), 5.17 (t, JH-H=6.03 Hz,
1H, NHCHCHCHNH), 3.82 (s, 6H, OCH3). 13C NMR (125 MHz,
CDCl3, 298 K): δ 156.7 (C=N), 149.2 (C-NH2, aromatic C), 140.5
(C-OCH3, aromatic C), 117.1, 114.0, 109.3 and 108.7 (aromatic C),
95.8 (NHCHCHCHN), 55.0 (OCH3). IR (KBr, cm-1): 3062–3008 (m,
CaromH), 2965–2939 (m, CH3), 2835 (m, OCH3), 1653 (vs), 1599 (vs),
1483 (m), 1365 (m), 1286 (m), 1196 (m, C-Nstretching), 1049 (s), 931
(m), 829 (m), 764 (m, NHdef), 685 (m, CH out of plane bending, m-
substituted benzenes).
Preparation of 7-methoxy-2,4-dimethylquinolinium 4-methylbenze-
nesulfonate The product was collected as pale yellow solid. Yield
1.0 g (1%). Elemental anal. (%) for C19H21NO4S: C, 63.49; H, 5.89;
N, 3.90; S, 8.92. Found: C, 63.5; H, 5.8; N, 3.8. 1H NMR (500 MHz,
DMSO-d6, 298 K): δ 8.31 (d, JH-H=9.31 Hz, 1H, Ar), 7.68 (s, 1H,
Ar), 7.55 (d, JH-H=7.01 Hz, 1H, Ar), 7.52 (d, JH-H=7.97 Hz, 2H, Ar-
SO3), 7.47 (s, 1H, Ar), 7.15 (d, JH-H=7.80 Hz, 2H, Ar-SO3), 4.02 (s,
3H, OCH3), 2.87 (s, 3H, C(CH3)CH(CH3)CN), 2.85 (s, 3H, C(CH3)-
CH(CH3)CN), 2.32 (s, 3H, CH3-Ar-SO3). The signal for -SO3H or
NH+ was not observed. 13C NMR (125 MHz, DMSO-d6, 298 K): δ
163.1 (C=N), 155.7 (C-N), 145.2, 139.7, 128.0 and 125.4 (aromatic
CH3-Ar-SO3), 138.8 (aromatic C-OCH3), 127.3, 121.5, 121.3 and
120.5 (aromatic C), 99.7 (C(CH3)CH(CH3)CN), 56.1 (OCH3), 20.7
(CH3-Ar-SO3), 20.2 (C(CH3)CH(CH3)CN), 19.0 (C(CH3)CH(CH3)-
CN).
LHPH; N,N′-prop-1-en-1-yl-3-ylidene-bis(4-methoxyaniline) (Richards
and Webb, 1976; Kikugawa and Sugimura, 1986) The product was
collected as yellow solid. Yield 2.0 g (43% overall, calculated on 2,4-
pentandione). Elemental anal. (%) for C17H18N2O2: C, 72.32; H, 6.43;
N, 9.92. Found: C, 72.3; H, 6.4; N, 9.8. Melting point 121–123°C.
1H NMR (500 MHz, CDCl3, 298 K): δ 12.22 (br s, 1H, NH), 7.64
(d, JH-H=6.33 Hz, 2H, NHCHCHCHN), 7.05 (d, JH-H=8.67 Hz,
4H, Ar), 6.89 (d, JH-H=8.83 Hz, 4H, Ar), 5.05 (t, JH-H=5.56 Hz, 1H,
NHCHCHCHNH), 3.81 (s, 6H, OCH3). 13C NMR (125 MHz, CDCl3,
298 K): δ 156.4 (C=N), 148.2 (C-NH2, aromatic C), 140.6 (C-OCH3,
aromatic C), 119.4, 114.8 (aromatic C), 94.4 (NHCHCHCHN), 55.7
(OCH3). IR (KBr, cm-1): 3072–3006 (w, CaromH), 2959–2901 (m, CH3),
2839 (m, OCH3), 1647 (s), 1557 (m), 1516 (vs), 1290 (s), 1244 (vs),
1033 (m), 1179 (m, C-Nstretching), 830 (s, CH out of plane bending,
p-substituted benzenes), 757 (w, NHdef).
Preparation of LCM1/2Li·({[3-ClC6H4]N(Me)CCH(Me)C=O}Li) The
lithiation of ligand LCM1/2H was carried out under an argon atmo-
sphere. The ligand LCM1/2H (1.33 g, 0.065 mol) was dissolved
in dried Et2O (15 ml). Yellow solution was formed and cooled to
-78°C. 1.6 m Solution of n-BuLi in hexane (4.1 ml, 6.56 mmol) was
added dropwise to the reaction mixture. Orange-white suspension
of LCM1/2Li was formed immediately. At the end of the reaction, the
solution was slowly warmed to room temperature. Lithium LCM1/2Li
salt was used without further purification for reactions with Sn(IV)
1
compounds immediately. H NMR (500 MHz, toluene-d8, 298 K):
δ 7.01 (t, JH-H=7.92 Hz, 1H, Ar), 6.47 (d, JH-H=8.16 Hz, 1H, Ar),
6.40–6.37 (m, 2H, Ar), 4.90 (s, 1H, NC(CH3)CHC(CH3)O), 3.39
(s, 3H, OCH3), 1.65 (s, 3H, NC(CH3)CHC(CH3)O), 1.58 (s, 3H,
NC(CH3)CHC(CH3)O). 13C NMR (125 MHz, toluene-d8, 298 K): δ
175.8 (C=O), 168.5 (C-N), 160.8 (C-N, aromatic C), 153.7 (C-OCH3
aromatic C), 129.7, 114.6, 109.0 and 107.8 (aromatic CH), 99.6
(NC(CH3)CHC(CH3)O), 54.6 (OCH3), 28.1 (NC(CH3)CHC(CH3)O),
LCClO1/2H; 4-[(2-chlorophenyl)amino]pent-3-en-2-one (Musker and
Sakhawat, 1966) In a slight modification of the literature proce-
dure (Carey et al., 2003; Chen et al., 2005), 2,4-pentandione (25 ml,
0.24 mol) and o-chloroaniline (25 ml, 0.24 mol) reacted equimolar.
The product was collected as yellow oil at 115–135°C (pressure
266 Pa). Yield 7.5 g (15%). Elemental anal. (%) for C17H18N2O2: C,
63.01; H, 5.77; Cl, 16.91; N, 6.68. Found: C, 63.1; H, 5.8; Cl, 16.8;
7
21.9 (NC(CH3)CHC(CH3)O). Li NMR (194 MHz, toluene-d8, 298
K): δ -3.22. 1H NMR (500 MHz, THF-d8, 298 K): δ 7.05 (t, JH-H=7.74
Hz, 1H, Ar), 6.47 (d, JH-H=7.73 Hz, 1H, Ar), 6.34–6.32 (m, 2H, Ar),
4.73 (s, 1H, NC(CH3)CHC(CH3)O), 3.67 (s, 3H, OCH3), 1.69 (s,
3H, NC(CH3)CHC(CH3)O), 1.65 (s, 3H, NC(CH3)CHC(CH3)O).
13C NMR (125 MHz, THF-d8, 298 K): δ 178.7 (C=O), 167.1 (C-N),
161.1 (C-N, aromatic C), 155.1 (C-OCH3 aromatic C), 129.7, 115.8,
108.9 and 108.5 (aromatic CH), 98.0 (NC(CH3)CHC(CH3)O), 55.2
(OCH3), 28.5 (NC(CH3)CHC(CH3)O), 21.9 (NC(CH3)CHC(CH3)O).
7Li NMR (194 MHz, THF-d8, 298 K): δ 1.40.
1
N, 6.7. H NMR (500 MHz, CDCl3, 298 K): δ 12.40 (s, 1H, NH),
7.33–7.15 (m, 4H, Ar), 5.16 (s, 1H, NHC(CH3)CHC(CH3)O), 2.03 (s,
3H, NHC(CH3)CHC(CH3)O), 1.75 (s, 3H, NHC(CH3)CHC(CH3)O.
13C NMR (125 MHz, CDCl3, 298 K): δ 197.5 (C=O), 159.15 (C-N),
140.2 (C-NH, aromatic C), 130.5 (C-Cl, aromatic C), 128.5, 127.2,
123.8 and 121.4 (aromatic CH), 98.5 (NHC(CH3)CHC(CH3)O), 29.3
(NHC(CH3)CHC(CH3)O), 19.8 (NHC(CH3)CHC(CH3)O).
LCClP1/2H; 4-[(4-chlorophenyl)amino]pent-3-en-2-one (Zhuo, 1997)
In a slight modification of the literature procedure (Carey et al.,
2003), 2,4-pentandione (25 ml, 0.24 mol) and o-chloroaniline (30 g,
0.24 mol) reacted equimolar. Most of the toluene was distilled of the
reaction mixture. The product was collected as yellow brown solid.
Yield 6.0 g (12%). Elemental anal. (%) for C17H18N2O2: C, 63.01;
H, 5.77; Cl, 16.91; N, 6.68. Found: C, 63.1; H, 5.8; Cl, 16.7; N,
6.5. 1H NMR (500 MHz, CDCl3, 298 K): δ 12.42 (s, 1H, NH), 7.25
(d, JH-H=8.67 Hz, 2H, Ar), 6.98 (d, JH-H=8.62 Hz, 2H, Ar), 5.17 (s,
1H, NHC(CH3)CHC(CH3)O), 2.06 (s, 3H, NHC(CH3)CHC(CH3)O),
1.94 (s, 3H, NHC(CH3)CHC(CH3)O. 13C NMR (125 MHz, CDCl3,
298 K): δ 196.5 (C=O), 159.7 (C-N), 138.4 (C-NH, aromatic C),
130.9 (C-Cl, aromatic C), 128.9 and 127.3 (aromatic CH), 98.0
Preparation of LCM1/2Bu3Sn·({[3-ClC6H4]N(Me)CCH(Me)C=O}Sn-
n-Bu3) from LCM1/2Li and n-Bu3SnCl n-Bu3SnCl (1.46 ml, 0.0054
mol) was suspended in Et2O (15 ml) and cooled to -78°C. LCM1/2Li in
Et2O (15 ml) prepared from LCM1/2H (1.12 g, 0.0054 mol) was added.
The reaction mixture was slowly warmed to room temperature and
then filtered from LiCl. The crude reaction mixture was washed twice
1
with hexane (yield 86%). H NMR (500 MHz, toluene-d8, 298 K):
δ 6.35–6.13 (m, 4H, Ar), 5.14 (s, 1H, NC(CH3)CHC(CH3)O), 3.52
(s, 3H, OCH3), 2.51 (m, 6H, Sn(CH2CH2CH2CH3)3), 1.70 (m, 6H,
Sn(CH2CH2CH2CH3)3), 1.57 (s, 3H, NC(CH3)CHC(CH3)O), 1.41
(m, 6H, Sn(CH2CH2CH2CH3)3), 1.34 (s, 3H, NC(CH3)CHC(CH3)O),
0.92 (m, 9H, Sn(CH2CH2CH2CH3)3). 119Sn-NMR (134 MHz, toluene-
d8, 298 K): δ 28.05.
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Sn and Li complexes of β-diketiminates/β -aminoketones 25
Alternative preparation of LCM1/2Bu3Sn from LCM1/2H and n-Bu3-
SnH n-Bu3SnH (1.74 ml, 0.0065 mol) was suspended in Et2O (15
ml) and cooled to -78°C. LCM1/2H (1.33 g, 0.0065 mol) in Et2O (15
ml) was added. The reaction mixture was slowly warmed to room
temperature and vacuum evaporated to give essentially the same
NMR spectra as in the previous case with similar yield of 82%.
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Preparation of LCM1/2Ph3Sn·({[3-ClC6H4]N(Me)CCH(Me)C=O}-
SnPh3) Ph3SnCl (2.47 g, 0.0064 mol) was suspended in Et2O (15
ml) and cooled to -78°C. LCM1/2Li in Et2O (15 ml) prepared from
LCM1/2H (1.32 g, 0.0064 mol) was added. The reaction mixture was
slowly warmed to room temperature and then filtered from LiCl.
The crude reaction mixture was washed twice with hexane (yield
72%). 1H NMR (500 MHz, toluene-d8, 298 K): δ 7.89–7.59 (m, 8H,
Ar), 7.15 (s, 1H, Ar), 6.96 (t, JH-H=6.36 Hz, 1H, Ar), 6.82–6.70 (m,
6H, Ar), 6.32–6.20 (m, 3H, Ar), 5.85 (s, 1H, NC(CH3)CHC(CH3)O),
3.27 (s, 3H, OCH3), 1.47 (s, 3H, NC(CH3)CHC(CH3)O), 1.25 (s, 3H,
NC(CH3)CHC(CH3)O). 119Sn-NMR (134 MHz, toluene-d8, 298 K):
δ -119.8.
Preparation of LCM1/2Ph2SnCl·({[3-ClC6H4]N(Me)CCH(Me)C=O}-
SnPh2Cl) Ph2SnCl2 (1.96 ml, 0.0057 mol) was suspended in Et2O
(15 ml) and cooled to -78°C. LCM1/2Li in Et2O (15 ml) prepared from
LCM1/2H (1.17 g, 0.0057 mol) was added. The reaction mixture was
slowly warmed to room temperature and then filtered from LiCl. The
crude reaction mixture was washed twice with hexane (yield 68%).
1H NMR (500 MHz, toluene-d8, 298 K): δ 7.62–7.51 (m, 8H, Ar),
7.38–7.15 (m, 6H, Ar), 5.61 (s, 1H, NC(CH3)CHC(CH3)O), 3.43
(s, 3H, OCH3), 1.30 (s, 3H, NC(CH3)CHC(CH3)O), 1.15 (s, 3H,
NC(CH3)CHC(CH3)O). 119Sn-NMR (134 MHz, toluene-d8, 298 K):
δ -45.1.
Preparation of LHPSnN[Si(CH3)3]2·([4-(MeO)C6H4]N=(H)CCH(H)-
C[4-(MeO)C6H4]NSnN(SiMe3)2) The preparation was car-
ried out under inert atmosphere of argon. Lappert’s stannylene
(Sn{N[Si(Me)3]2}2) (Harris and Lappert, 1974; Davidson et al., 1976)
was dissolved in hexane and cooled to -78°C. Suspension of LHP
H
in dried hexane was added dropwise. Dark red reaction mixture was
slowly warmed to room temperature. The reaction mixture was crys-
tallized from toluene (yield 77%). 1H NMR (500 MHz, THF-d8, 298
K): 7.40 (d, JH-H=7.02 Hz, 2H, NHCHCHCHN), 7.28 (d, JH-H=8.72
Hz, 4H, Ar), 6.89 (d, JH-H=8.72 Hz, 4H, Ar), 4.96 (t, JH-H=6.52 Hz,
1H, NHCHCHCHNH), 3.72 (s, 6H, OCH3), 0.19 (s, 18H, NSi(CH3)3).
13C NMR (125 MHz, THF-d8, 298 K): δ 158.4 (C=N), 154.7 (C-N,
aromatic C), 143.7 (C-OCH3, aromatic C), 123.7, 115.3 (aromatic C),
96.6 (NHCHCHCHN), 55.7 (OCH3), 6.52 (NSi(CH3)3). 119Sn-NMR
(134 MHz, THF-d8, 298 K): δ -164.1.
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Received February 16, 2012; accepted March 6, 2012; previously
published online April 18, 2012
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