Pentacoordinate silicon complexes with N-(2-pyridylmethyl)salicylamide as a dianionic (ONN′) tridentate chelator

Article abstract of DOI:10.1002/zaac.201200084

The title compound, N-(2-pyridylmethyl)salicylamide (1), was synthesized by ester aminolysis of methyl salicylate and 2-picolylamine. In the presence of triethylamine as a supporting base, the salicylamide moiety reacts with the organodichlorosilanes RR'SiCl₂ to form the desired six-membered heterocycles of the type RR'Si-O-(o-C₆H₄)-C(=O)N(pic), with pic being the 2-pyridylmethyl (i.e., 2-picolyl) moiety and RR′ = Me, Me (2a); Me, Ph (2b); Ph, Ph (2c); Bn, Bn (2d); All, Ph (2e) and Ph, H (2f). Despite the absence of notable ring strain release Lewis acidity (i.e., only a six-membered chelate is formed by the dianion, and smaller rings are not present in the compound), the poor electron withdrawal from silicon by its C- or H- substituents and the flexible methylene bridge between the salicylamide and the pyridine moiety, the pyridine N donor atom furnishes pentacoordinate silicon coordination spheres in all of these compounds 2a-2f. The coordination number of the silicon atom was confirmed by single-crystal X-ray diffraction analysis for the solid state and by ²⁹Si NMR spectroscopy for the solution state. Copyright

Full text of DOI:10.1002/zaac.201200084

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DOI: 10.1002/zaac.201200084
Pentacoordinate Silicon Complexes with N-(2-pyridylmethyl)salicylamide as
a Dianionic (ONNЈ) Tridentate Chelator
Dana Schwarz,[a] Erica Brendler,[b] Edwin Kroke,[a] and Jörg Wagler*[a]
Dedicated to Professor Klaus Jurkschat on the Occasion of His 60th Birthday
Keywords: Hypercoordination; Organosilicon complexes; Pentacoordination; Pyridine; Silicon
Abstract. The title compound, N-(2-pyridylmethyl)salicylamide (1), formed by the dianion, and smaller rings are not present in the com-
was synthesized by ester aminolysis of methyl salicylate and 2-picolyl-
pound), the poor electron withdrawal from silicon by its C– or H–
amine. In the presence of triethylamine as a supporting base, the sali- substituents and the flexible methylene bridge between the salicylam-
cylamide moiety reacts with the organodichlorosilanes RRЈSiCl2 to ide and the pyridine moiety, the pyridine N donor atom furnishes
form the desired six-membered heterocycles of the type RRЈSi–O–(o- pentacoordinate silicon coordination spheres in all of these compounds
C6H4)–C(=O)N(pic), with pic being the 2-pyridylmethyl (i.e., 2-pico-
2a–2f. The coordination number of the silicon atom was confirmed by
lyl) moiety and RRЈ = Me,Me (2a); Me,Ph (2b); Ph,Ph (2c); Bn,Bn single-crystal X-ray diffraction analysis for the solid state and by 29Si
(2d); All,Ph (2e) and Ph,H (2f). Despite the absence of notable ring NMR spectroscopy for the solution state.
strain release Lewis acidity (i.e., only a six-membered chelate is
Introduction
Among the ligands reported to be capable of forming hyper-
coordinate silicon complexes[1] pyridine is well known to react
with halosilanes to form adducts with an increased coordina-
tion number of the silicon atom,[2] and a variety of 4- or 3-
substituted pyridines was found to exhibit related ligand prop-
erties,[3] whereas the greater steric bulk of 2- or 2,6-substituted
Scheme 1. Examples of neutral and cationic halosilane pyridine ad-
pyridines lowers the stability of those Lewis acid base adducts
dramatically.[3b,4] The examples in Scheme 1 outline the gene-
ral coordination patterns encountered with pyridine silane
complexes, which may involve ionic dissociation of silicon
halide (Si–X) bonds. The use of chelating ligands with pyridine
functionality, e.g., 2,2Ј-bipyridyl or 1,10-phenanthroline, sup-
ports the formation of such Lewis acid base adducts.[2c,5]
Even though a large portfolio of halogen rich pyridine ha-
losilane complexes are known (mostly of silanes of the type
SiX4, HSiX3, H2SiX2; X = halide), the role of pyridine as an
additional lone pair donor towards silicon is evident for an
ducts with hexa- or pentacoordinate silicon atom.
even greater variety of silanes from the catalytic influence of
pyridines on substitution reactions at silanes, which include
mono-, di- and triorganosilane derivatives.[6] Structural evi-
dence for neutral pyridine adducts of monoorganosilanes, how-
ever, is limited to a few examples,[7] and to the best of our
knowledge there is no crystallographic evidence for neutral
pyridine diorganosilane adducts.[8] Some hypercoordinate sili-
con complexes with X2SiC2 skeleton and pyridine donor moi-
ety have been reported, but in most cases the pyridine nitrogen
atom was part of a rigid chelate construction, which forced the
pyridine nitrogen lone pair to point in a similar direction like
a lone pair of the second donor atom, e.g., 8-oxyquinolinate,
1,10-phenanthroline, the anion of 1,2,3,4-tetrahydro-1,10-
phenanthroline, and others (Scheme 2, top).[9] Gómez et al. and
Holmes et al. already reported on neutral pentacoordinate dior-
ganosilicon complexes with an additional pyridine donor moi-
ety bound to the ligand backbone via a flexible alkyl group,
but they needed to clamp the pyridine donor to silicon by using
two anionic anchors in 2,6-position of the pyridine (Scheme 2,
bottom left).[10] Recently, Tacke et al. reported on pentacoordi-
* Dr. J. Wagler
Fax: +49-3731-39 4058
E-Mail: joerg.wagler@chemie.tu-freiberg.de
[a] Institut für Anorganische Chemie
TU Bergakademie Freiberg
Leipziger Str. 29
09596 Freiberg, Germany
[b] Institut für Analytische Chemie
TU Bergakademie Freiberg
Leipziger Str. 29
09596 Freiberg, Germany
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201200084 or from the au-
thor.
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D. Schwarz, E. Brendler, E. Kroke, J. Wagler
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nate monoorganosilicon complexes with a pyridine donor moi-
Whereas the presence of one or a half water molecule per
ety, which was anchored to silicon via only one –CH2–N– arm ligand molecule could be camouflaged in the 1H NMR spectra
in 2-position, which offers rotational degrees of freedom, thus by rapid exchange with other acidic protons, the new crystal
not forcing the pyridine to bind to silicon (Scheme 2, bottom structure of 1 (Figure 1) revealed that it crystallizes in an anhy-
right).[11]
drous manner. Thus, the X-ray diffraction analysis underlines
the results of the elemental analysis, which are in accord with
the anhydrous nature of the gross product. In the crystal pack-
ing the asymmetric unit consists of one molecule of 1. To-
gether with an inversion-related molecule it forms a dimer via
intermolecular O–H···N hydrogen bonds to the pyridine nitro-
gen atom. The configuration of the molecule of 1 itself is
furthermore stabilized by an intramolecular N–H···O hydrogen
bond from the amide NH group to the hydroxyl oxygen atom.
The torsion angle C7–N1–C8–C9 [–82.7(1)°] indicates that the
pyridine nitrogen atom N2 is significantly out of the least-
squares plane of atoms C1–C7, O1, N1 [2.282(2) Å] and a
conformational change is required for in-plane coordination of
a silicon atom within the (ONNЈ) donor set.
Scheme 2. Silicon complexes with pyridine moieties anchored to sili-
con via anionic ligand backbones.
In the course of our investigations of (ONNЈ) donor systems
in the coordination sphere of silicon,[12] now we also have
included the neutral pyridine donor moiety as a dangling arm.
In contrast to the (SNNЈ) ligand system utilized by Tacke et
al., the dianionic (ONNЈ) donor ligand 1 depicted in Scheme 3,
left,[13] should primarily give rise to (ON)-chelated silacycles
devoid of notable ring strain, as a six-membered chelate is
formed, and we want to minimize effects such as ring strain
release Lewis acidity[14] for our current investigation. There-
fore, this ligand appeared suitable to study the influence of
different diorgano substitution patterns at silicon on the coordi- Figure 1. ORTEP[15] diagram of the molecular structure of 1 in the
crystal (carbon bound hydrogen atoms are omitted for clarity, thermal
nation behavior of the pendant pyridine moiety.
displacement ellipsoids represent the 50% probability level, selected
atoms are labeled). The asymmetric unit consists of one molecule of
1, which forms a centrosymmetric dimer with the (–x, 2–y, –z) sym-
metry related molecule via intermolecular O–H···N hydrogen bonds.
The reactions of 1 with the dichlorosilanes depicted in
Scheme 3 (using triethylamine as a supporting base) did pro-
ceed rapidly, as was obvious from the amount of triethylamine
hydrochloride which formed instantly upon addition of the si-
lane to a solution of ligand and triethylamine in tetra-
hydrofuran (THF). In all of the above cases the silicon com-
Scheme 3. Syntheses of silicon complexes with the dianion of 1 as an
(ONNЈ) donor ligand. R,RЈ = Me,Me (2a), Me,Ph (2b), Ph,Ph (2c),
Bn,Bn (2d), Ph,All (2e), Ph,H (2f).
plexes were soluble in THF, thus allowed for separation from
the hydrochloride by filtration. Upon removal of the solvent
from the filtrate (by trap condensation under reduced pressure)
the products remained as viscous oils, which required different
Results and Discussion
A synthesis route towards ligand 1 is reported in the litera- solvents for successful crystallization (see Experimental Sec-
ture,[13] but the authors report the crystallization of the hydrate tion). All compounds 2a–2f gave rise to crystals of good qual-
of this ligand, which needs to be circumvented when preparing ity for single-crystal X-ray diffraction analyses (Figure 2, Fig-
a ligand for silicon coordination chemistry. Furthermore, the ure 3, Figure 4, Figure 5, Figure 6, and Figure 7). Whereas
original procedure involved dimethylformamide as a solvent compounds 2a–2e crystallized in a solvent free lattice, com-
for the reaction and chloroform as a second solvent for extrac- pound 2f crystallized as THF solvate 2f·THF. Further note-
tion. We pursued a straightforward synthesis of 1, and the con- worthy features of the crystal structures were found with 2c,
densation of methyl salicylate and picolylamine in n-pentanol which comprises three molecules of this complex in the asym-
turned out to be successful yielding the crystalline anhydrous metric unit, and with 2e, the allyl group of which is twofold
ligand 1 directly from the reaction solution.
disordered in a cross-wise manner in ratio 0.917(4):0.083(4).
2
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Pentacoordinate Silicon Complexes with N-(2-pyridylmethyl)salicylamide
Figure 2. ORTEP[15] diagram of the molecular structure of 2a in the
crystal (hydrogen atoms are omitted for clarity, thermal displacement
ellipsoids represent the 50% probability level, selected atoms are lab-
eled). The asymmetric unit consists of one molecule of 2a. Selected
bond lengths /Å and angles /°: Si1–O1 1.742(1), Si1–N1 1.802(1),
Si1–N2 2.069(1), Si1–C14 1.874(2), Si1–C15 1.876(2), O1–Si1–N2
172.96(5), N1–Si1–C14 121.58(6), N1–Si1–C15 115.50(6), C14–Si1–
C15 121.12(7).
Figure 4. ORTEP[15] diagram of the molecular structure of one mole-
cule of 2c in the crystal (hydrogen atoms are omitted for clarity, ther-
mal displacement ellipsoids represent the 50% probability level, se-
lected atoms are labeled). The asymmetric unit consists of three mole-
cules of 2c, which reveal similar conformation, major differences can
be found in the relative orientation of the Si-bound phenyl groups.
Selected bond lengths /Å and angles /° of the depicted molecule: Si1–
O1 1.720(1), Si1–N1 1.796(1), Si1–N2 2.041(1), Si1–C14 1.879(2),
Si1–C20 1.898(2), O1–Si1–N2 174.60(6), N1–Si1–C14 114.16(7),
N1–Si1–C20 123.32(7), C14–Si1–C20 120.64(8).
Figure 3. ORTEP[15] diagram of the molecular structure of 2b in the
crystal (hydrogen atoms are omitted for clarity, thermal displacement
ellipsoids represent the 50% probability level, selected atoms are lab-
eled). The asymmetric unit consists of one molecule of 2b. Selected
bond lengths /Å and angles /°: Si1–O1 1.734(1), Si1–N1 1.798(1),
Si1–N2 2.053(1), Si1–C14 1.875(1), Si1–C15 1.881(1), O1–Si1–N2
174.18(2), N1–Si1–C14 121.27(2), N1–Si1–C15 117.17(2), C14–Si1–
C15 119.81(2).
Figure 5. ORTEP[15] diagram of the molecular structure of 2d in the
crystal (hydrogen atoms are omitted for clarity, thermal displacement
ellipsoids represent the 50% probability level, selected atoms are lab-
eled). The asymmetric unit consists of one molecule of 2d. Selected
bond lengths /Å and angles /°: Si1–O1 1.750(1), Si1–N1 1.799(1),
Si1–N2 2.043(1), Si1–C14 1.897(1), Si1–C21 1.904(1), O1–Si1–N2
173.33(5), N1–Si1–C14 122.68(5), N1–Si1–C21 115.79(5), C14–Si1–
C21 120.16(6).
The mutual feature of the silicon complex molecules 2a–2f
in their crystal structures is the distorted trigonal bipyramidal
coordination sphere about the silicon atom. Hence, the ligand 2a–2e range from 172.83(4)° (2e) to 175.94(7)° (one of the
has adopted a different conformation than in the solid-state three independent molecules of 2c). The notable deviation of
structure of its protonated form compound 1. The torsion 2f from this general coordination pattern can be rationalized
angles which correspond to C7–N1–C8–C9 in the structure of by the lower steric demand of the Si-bound hydrogen atom.
1 are now ranging from 160.9(1)° (2a, 2d) via 164.3(1)° (2b), The decreased axial angle in 2f is accompanied by a notable
167.3(1)° (2e) and 167.5(1)°, 171.2(1)°, 174.3(1)° (2c) to shortening of the bond Si1–N2 [1.993(1) Å in 2f], which ran-
179.5(1)° (2f). This order does not hint at any particular steric ges between 2.041(1) Å and 2.069(1) Å in compounds 2a–2e.
influence of the Si-bound substituents, and is therefore most The pyridine donor trans-influenced bond O1–Si1 [lengths in
likely dominated by the intermolecular packing in the crystal the range of 1.720(1) Å to 1.750(1) Å] is notably longer than
structure.
the related Si–O bond of 1.648(1) Å in the pyridine donor free
The greatest deviation from a trigonal bipyramidal coordina- molecule 3c depicted in Scheme 4.[9a] The Si1–N1 bonds
tion sphere is found in 2f, with an O1–Si1–N2 angle of [lengths in the range of 1.794(1) Å to 1.802(1) Å in 2a–2f] are
164.01(4)°, whereas the corresponding angles in compounds affected by the pyridine donor action to a similar extent, thus
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Scheme 4. Pyridine-free “benchmark” compounds, which are structur-
ally related to 2a, 2b, and 2c, respectively, with their 29Si NMR shifts.
Within the margins of 328.5° for an ideal tetrahedron and 360°
for a trigonal bipyramid, the sum of angles N1–Si1–C and C–
Si1–C provide a measure for the progress of the transition from
the tetrahedral to the trigonal bipyramidal coordination sphere.
With sums of equatorial angles ranging between 357.79° (in
one of the three independent molecules of 2c) and 358.63°
(2d), corresponding to 93.0% and 95.7% progress along this
idealized reaction coordinate, respectively, the above com-
plexes 2a–2f reflect similar donor influence from the pyridine
moiety.
Figure 6. ORTEP[15] diagram of the molecular structure of 2e in the
crystal (hydrogen atoms are omitted for clarity, thermal displacement
ellipsoids represent the 50% probability level, selected atoms are lab-
eled). The asymmetric unit consists of one molecule of 2e. The allyl
group is twofold disordered (in a cross-wise manner about the C=C
bond, site occupancies refined to 0.917(4) and 0.083(4)), only the pre-
dominant part is depicted. Selected bond lengths /Å and angles /°: Si1–
O1 1.733(1), Si1–N1 1.794(1), Si1–N2 2.069(1), Si1–C14 1.891(1),
Si1–C17 1.880(1), O1–Si1–N2 172.83(4), N1–Si1–C14 120.06(5),
N1–Si1–C17 119.47(5), C14–Si1–C17 118.95(5).
With reference to the complexes reported by Tacke et al.
(Scheme 2, bottom right),[11] the pyridine donor influence ap-
pears to be pronounced in their complexes, with Si–N(pyrid-
ine) bond lengths ranging between 1.970(1) Å (for R/X =
Ph/O3SCF3) and 2.029(2) Å (for R/X = Me/SePh). These
slightly shorter bond lengths can be attributed to various differ-
ences in the substitution pattern, i.e., a more electronegative
substituent in the equatorial plane, an additional five-mem-
bered chelate in the complex and, last but not least, the sulfur
atom trans to the pyridine donor. As to the role of sulfur versus
oxygen, in a previous study we had found similar behavior of
an N-donor, i.e., N–Si bond length shortening upon replacing
the trans-disposed substituent (F) by the heavier congener (Cl),
and Tacke et al. had found that in one of their silicon com-
plexes a thiophenolate substituent supported silicon pentaco-
ordination, whereas the corresponding phenoxy derivative
formed a compound with tetracoordinate silicon atom.[16] With
reference to the sum of equatorial angles about silicon the
above mentioned compounds from the report by Tacke et al.
exhibit similar features, i.e., sum of angles = 358.42° (for
R/X = Ph/O3SCF3) and 358.02° (for R/X = Me/SePh).
Figure 7. ORTEP[15] diagram of the molecular structure of 2f in the
crystal structure of 2f·THF (solvent molecule as well as carbon-bound
hydrogen atoms are omitted for clarity, thermal displacement ellipsoids
represent the 50% probability level, selected atoms are labeled). The
asymmetric unit consists of one molecule of 2f and one molecule of
tetrahydrofuran. Selected bond lengths /Å and angles /°: Si1–O1
1.723(1), Si1–N1 1.802(1), Si1–N2 1.993(1), Si1–C14 1.881(1), Si1–
H1a 1.388(14), O1–Si1–N2 164.01(4), N1–Si1–C14 111.60(4), N1–
Si1–H1a 132.8(6), C14–Si1–H1a 113.7(6).
The pentacoordination of the silicon atoms of above com-
pounds is generally retained in CDCl3 solution, as is apparent
from their 29Si NMR shifts [δ29Si(CDCl3)/δiso29Si(CP/MAS)]:
2a –46.1/–63.1, 2b –65.2/–75.7, 2c –81.2/–88.8, 2d –66.2/
–71.3, 2e –74.2/–77.2, 2f –90.7/–94.2. Without the additional
being also notably longer than the Si–N bond in the reference donor action of the pyridine nitrogen atom, compounds 2a, 2b,
molecule 3c in Scheme 4 [1.720(2) Å]. Only the Si–C bonds and 2c should exhibit 29Si chemical shifts similar to those of
[1.850(2) and 1.861(2) in 3c] are elongated to lesser extent, the compounds 3a, 3b, and 3c, respectively, which are depicted
resulting in Si–C(Ph) bond lengths of up to 1.90 Å in above in Scheme 4.[9a] The latter comprise a similar di-anionic che-
pentacoordinate silicon compounds.
late around the silicon atom, which furnishes a six-membered
With respect to the tetracoordinate silicon compounds in heterocycle. Even though the 29Si NMR shifts in CDCl3 solu-
Scheme 4, the additional pyridine donor action in 2a–2f can tion indicate pentacoordination of the silicon atom, some reso-
be interpreted along the coordinate of a capping of the tetrahe- nances already appear noticeably down-field shifted with re-
dral face opposite the Si–O bond, which results in planariz- spect to the resonance in the solid state. This feature is particu-
ation of the Si–N1 and Si–C bonds around the silicon atom. larly pronounced for compounds 2a and 2b (with down-field
4
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Pentacoordinate Silicon Complexes with N-(2-pyridylmethyl)salicylamide
shifts Δδ of 17 ppm and 10.5 ppm, respectively). 29Si variable mation of two NimineǞSi bonds, i.e., –32.65 kJ·mol–1 for one
temperature (VT) NMR studies of these two compounds re-
vealed significant response of the chemical shift to the tem-
N
imineǞSi bond).
As the Si–X (X = C, H) bond activation in hexacoordinate
perature, i.e., up-field shift upon cooling, down-field shift upon silicon complexes is a well-known phenomenon, and resultant
heating. This temperature dependence indicates the existence Si–X bond cleavage reactions have been observed in different
of equilibria between tetra- and pentacoordinate silicon com- complex systems (Scheme 5, top and middle),[17] we probed
pounds (as depicted in Scheme 3). Using the 29Si chemical the reactivity of compounds 2e and 2f towards benzaldehyde.
shifts of compounds 3a and 3b as approximate reference val- The respective complex was dissolved in CDCl3, benzaldehyde
ues for the chemical shifts of 2a and 2b, respectively, with (50% excess) was added, and the solution was monitored by
1
tetracoordinate silicon atom, and the chemical shifts from solid 29Si and H NMR spectroscopy over several days. The 29Si
state NMR experiments as references for the conformers with NMR spectra did not hint at significant additional donor action
pentacoordinate silicon atom, the temperature dependence of arising from the aldehyde oxygen atom, as we found the reso-
the equilibrium constant K can be determined from the posi- nance signals of the starting materials. Furthermore, a shift of
tion of δ29Si(T). From ln(K) vs. 1/T plots the thermodynamic X (H or allyl) should have given rise to new characteristic
data ΔH and ΔS for the N(pyridine)ǞSi coordination of these peaks in the 1H NMR spectrum, but we only observed the
two compounds were determined (for details see the Support- signals of the starting materials.
ing Information). The results (2a: ΔH = –16.4 kJ·mol–1, ΔS =
–46.5 J·mol–1·K–1; 2b: ΔH
=
–15.0 kJ·mol–1, ΔS
=
–36.0 J·mol–1·K–1 for the formation of the NpyridineǞSi coordi-
nation) appear counterintuitive. One would expect similar be-
havior of the reaction entropies because of the similar degrees
of freedom gained upon Npyridine–Si bond dissociation. We
need to point out that the data obtained for 2b has to be han-
dled with care because of the small fraction (ca. 20%) of its
chemical shift range (i.e., between the boundaries for the
chemical shifts of the isomers with tetra- and pentacoordinate
silicon atom) covered by the VT NMR experiment, whereas
the data for 2a cover more than 30% of its chemical shift
range. With respect to the reaction enthalpy, which appears to
be similar for 2a and 2b, we find that the pyridine coordination
is significantly less exothermic than the coordination of a di-
imine moiety to a silicon atom with SiO2Ph2 substitution
pattern within a ligand system as depicted in Scheme 5 top.[17a]
In the latter case we found ΔH = –65.3 kJ·mol–1 (for the for-
Conclusions
We have shown that the flexible pyridine moiety of N-(2-
pyridylmethyl)salicylamide coordinates to the silicon atom of
diorganosilicon groups within the salicylamide (ON) chelate.
The pyridine donor action is observed for both those com-
plexes with the more electronegative phenyl substituents and
those with the less electronegative methyl substituents in a
similar manner with respect to bond lengths in the silicon coor-
dination sphere. In general, the pentacoordination of the silicon
atom is retained in CDCl3 solution, but a more or less pro-
nounced down-field shift of the 29Si resonance relative to the
29Si chemical shift of the solid hints at Npyridine–Si bond disso-
ciation in dynamic equilibria. This hypothesis was confirmed
by VT NMR studies.
Experimental Section
Syntheses were performed in an inert atmosphere of dry argon using
Schlenk line techniques and anhydrous solvents. NMR spectra (of
CDCl3 solutions) were recorded with a BRUKER DPX 400 spectrome-
ter (10 mm probe) using SiMe4 as internal standard for 1H, 13C and
29Si spectra. 29Si VT NMR spectra were recorded with a BRUKER
AVANCE 500 spectrometer (5 mm probe). The temperature was ad-
justed by the internal spectrometer temperature control system together
with a BCU extreme cooling unit (BRUKER). Low temperature cali-
bration was done using a sample of 4% methanol in [D4]methanol,
high temperature calibration using a sample of 80% 1,2-ethandiol in
[D6]DMSO according to the procedure given in the literature.[18] 29Si
solid state NMR spectra were recorded with a BRUKER AVANCE
400 WB spectrometer using a 7 mm probe with zirconia spinners. Ele-
mental microanalyses were performed with a Vario Micro Cube (ELE-
MENTAR). X-ray diffraction data were recorded with a BRUKER
NONIUS X8 diffractometer with APEX II CCD detector (in combina-
tions of phi and omega scans) using graphite monochromated Mo-Kα
radiation. The structures were solved by direct methods (SHELXS)
and refined with full-matrix least-squares on F2 (SHELXL).[19] All
non-hydrogen atoms were refined anisotropically. C-bound hydrogen
atoms were refined isotropically in idealized positions (riding model),
Si-, O- and N-bound hydrogen atoms were located from the residual
electron density map and were refined without restraints.
Scheme 5. Hydrogen- and allyl-shift reactions in hypercoordinate sili-
con complexes and attempted analogous reaction with the compounds
2e and 2f.
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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
CH3). 13C NMR (CDCl3): δ = 169.2 (C=O), [157.0, 155.2, 143.7,
138.9, 133.6, 129.9, 123.4, 121.9, 120.5, 119.6, 119.4 (aryl)], 47.2
(CH2), 4.2 (CH3). 29Si NMR (CDCl3): δ = –46.1, (CP/MAS): δiso
=
data can be obtained free of charge on quoting the depository numbers –63.1 ppm.
CCDC-867781 (1), -867782 (2a), -867783 (2b), -867784 (2c), -867785
(2d), -867786 (2e), and -867787 (2f·THF) (Fax: +44-1223-336-033;
E-Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk).
Crystal Structure Analysis of 2a: Single crystals were obtained di-
rectly from the synthesis. C15H16N2O2Si, Mr = 284.39, T = 100(2) K,
monoclinic, space group P21/c, a = 7.3258(4), b = 13.3140(7), c =
14.3057(8) Å, β = 90.386(2)°, V = 1395.28(13) Å3, Z = 4, ρcalcd.
=
Synthesis of Compound 1: In the literature [13], a method for the
preparation of this ligand is reported, but the yield is not provided, the
final product crystallized as mono-hydrate (which would be unsuitable
for subsequent reactions with chlorosilanes), and the procedure in-
volved reaction in dimethylformamide and extraction with chloroform.
Thus, we aimed at a more convenient synthesis which should give
access to anhydrous compound 1 along a straightforward procedure.
In an atmosphere of dry argon a solution of 2-picolylamine (10.0 g,
92.6 mmol), methylsalicylate (14.0 g, 92.1 mmol), and two drops of
N-methylimidazole in n-pentanol (20 mL) was stirred at 165 °C (oil
bath temperature) for 8 h and the methanol formed was distilled off
the reaction flask. The initially colorless solution turned brownish-
yellow within this time. Upon cooling to room temperature the solution
was stored at 8 °C for 3 weeks to afford beige crystals of 1, which
were separated by decantation, repeatedly washed with ethanol
(3ϫ10 mL) and dried in air. Yield 6.65 g (29.1 mmol, 33%). M.p.
118 °C, Anal. found: C 68.43, H 5.09, N 12.25%, calcd. for
C13H12N2O2: C 68.41, H 5.30, N 12.27%. In CDCl3 solution the chem-
ical shifts of some 1H resonances are particularly concentration de-
1.354 Mg·m–3, μ(Mo-Kα) = 0.171 mm–1, F(000) = 600, 2θmax = 60.0°,
14028 collected reflections, 4078 unique reflections (Rint = 0.0386),
183 parameters, S = 1.037, R1 = 0.0428, wR2 = 0.1055 [I Ͼ 2σ(I)], R1
= 0.0672, wR2 = 0.1141 (all data), max./min. residual electron density
+0.594/–0.330 e·Å–3.
Synthesis of Compound 2b: A solution of ligand 1 (1.00 g,
4.63 mmol) and triethylamine (1.41 g, 13.9 mmol) in THF (30 mL)
was stirred at room temperature and methylphenyldichlorosilane
(0.97 g, 5.10 mmol) was added within 10 s. The mixture was stirred
for 2 h, whereupon the hydrochloride precipitate was filtered off and
washed with THF (10 mL). From the combined filtrate and washings
the solvent was removed under reduced pressure and the resultant
brownish oily residue was dissolved in warm toluene (1 mL) and THF
(4 mL). Upon storage at room temperature, crystallization commenced
within a few minutes. After 11 d the beige crystals were filtered off,
washed with 2.5 mL of a mixture of toluene and THF (1:4) and dried
in vacuo. Yield 1.0 g (3.5 mmol, 65%). M.p. 185 °C, Anal. found: C
69.47, H 5.25, N 8.08%, calcd. for C20H18N2O2Si: C 69.34, H 5.24,
pendent, the herein reported data refer to
a concentration of
1
0.15 mol·L–1. H NMR (CDCl3): δ = 12.44 (s broad, 1 H, OH), 8.58
(d 5.0 Hz, 1 H, aryl), 8.06 (s broad, 1, NH), 7.71 (m, 1 H, aryl), 7.57
(d 8.7 Hz, 1 H, aryl), 7.39 (m, 1 H, aryl), 7.33 (d 7.8 Hz, 1 H, aryl),
7.25 (m, 1 H, aryl), 6.98 (d 8.7 Hz, 1 H, aryl), 6.87 (m, 1 H, aryl),
4.61 (d 4.5 Hz, 2 H, CH2). 13C NMR (CDCl3): δ = 169.9 (C=O),
[161.5, 155.3, 148.9, 137.0, 134.2, 126.0, 122.7, 122.2, 118.7, 118.4,
114.4 (aryl)], 44.0 (CH2) ppm.
1
N 8.09%. H NMR (CDCl3): δ = 7.99 (dd 1.5 Hz, 7.6 Hz, 1 H, aryl),
7.88 (d, 5.1 Hz, 1 H, aryl), 7.83 (m, 1 H, aryl), 7.48 (d 7.9 Hz, 1 H,
aryl), 7.40–7.36 (mm, 2 H, aryl), 7.27–7.17 (mm, 5 H, aryl), 6.82 (m,
1 H, aryl), 6.75 (d 8.2 Hz, 1 H, aryl), 5.47, 5.06 (2d 19.6 Hz, 2 H,
CH2), 0.68 (s, 3 H, CH3). 13C NMR (CDCl3): δ = 170.1 (C=O), [157.2,
154.6, 143.5, 140.6, 139.5, 133.6, 132.7, 129.6, 128.5, 127.5, 123.4,
121.6, 120.2, 119.6, 119.2 (aryl)], 47.7 (CH2), 4.5 (CH3). 29Si NMR
(CDCl3): δ = –65.2, (CP/MAS): δiso = –75.7 ppm.
Crystal Structure Analysis of 1: Single crystals were obtained di-
rectly from the synthesis. C13H12N2O2, Mr = 228.25, T = 100(2) K,
monoclinic, space group P21/c, a = 10.7455(3), b = 13.2524(2), c =
Crystal Structure Analysis of 2b: Single crystals were obtained di-
rectly from the synthesis. C20H18N2O2Si, Mr = 346.45, T = 97(2) K,
monoclinic, space group P21/c, a = 12.6835(3), b = 8.5894(2), c =
7.5870(2) Å, β = 97.332(2)°, V = 1071.58(5) Å3, Z = 4, ρcalcd.
=
15.8348(3) Å, β = 98.486(1)°, V = 1706.21(7) Å3, Z = 4, ρcalcd.
=
1.415 Mg·m–3, μ(Mo-Kα) = 0.097 mm–1, F(000) = 480, 2θmax = 64.0°,
17157 collected reflections, 3682 unique reflections (Rint = 0.0420),
162 parameters, S = 1.088, R1 = 0.0480, wR2 = 0.1191 [I Ͼ 2σ(I)], R1
= 0.0718, wR2 = 0.1274 (all data), max./min. residual electron density
+0.469/–0.259 e·Å–3.
1.349 Mg·m–3, μ(Mo-Kα) = 0.154 mm–1, F(000) = 728, 2θmax = 104.0°,
118597 collected reflections, 19400 unique reflections (Rint = 0.0318),
227 parameters, S = 1.072, R1 = 0.0373, wR2 = 0.1147 [I Ͼ 2σ(I)], R1
= 0.0618, wR2 = 0.1238 (all data), max./min. residual electron density
+0.669/–0.350 e·Å–3.
Synthesis of Compound 2a: A solution of ligand 1 (1.00 g,
4.63 mmol) and triethylamine (1.41 g, 13.9 mmol) in tetrahydrofuran Synthesis of Compound 2c:
(THF, 30 mL) was stirred at room temperature and dimethyldichlorosi- 4.63 mmol) and triethylamine (1.41 g, 13.9 mmol) in THF (30 mL)
lane (0.66 g, 5.10 mmol) was added within 10 s. The mixture was was stirred at room temperature and diphenyldichlorosilane (1.29 g,
stirred for 1 h and stored at room temperature overnight, whereupon 5.10 mmol) was added within 10 s. The mixture was stirred for 2 h,
A solution of ligand 1 (1.00 g,
the hydrochloride precipitate was filtered off and washed with THF
(10 mL). From the combined filtrate and washings the solvent was
removed under reduced pressure and the resultant brownish oily resi-
whereupon the hydrochloride precipitate was filtered off and washed
with THF (7.5 mL). From the combined filtrate and washings the sol-
vent was removed under reduced pressure and the resultant brownish
due was dissolved in toluene (1.2 mL) and hexane (0.5 mL). Upon oily residue was dissolved in warm toluene (1.5 mL) and the solution
storage at 8 °C for 3 d the first beige crystals appeared, whereupon
further hexane (0.6 mL) was added and the mixture was stored at 8 °C
was stored at 8 °C for crystallization. After 4 d the beige crystals were
filtered off, washed with 1.5 mL of a mixture of toluene and THF (2:1)
for 4 weeks. Afterwards, the crystals were filtered off, washed with and dried in vacuo. Yield 1.64 g (4.01 mmol, 90%). M.p. 278 °C,
4 mL of a mixture of toluene and hexane (1:1) and dried in vacuo. Anal. found: C 72.89, H 4.94, N 6.71%, calcd. for C25H20N2O2Si: C
Yield 0.30 g (1.05 mmol, 23%). M.p. 139 °C, Anal. found: C 63.05,
H 5.49, N 9.86%, calcd. for C15H16N2O2Si: C 63.35, H 5.67, N
9.85%. 1H NMR (CDCl3): δ = 8.40 (d 5.4 Hz, 1 H, aryl), 8.04 (dd
1.6 Hz, 7.7 Hz, 1 H, aryl), 7.87 (m, 1 H, aryl), 7.49–7.25 (mm, 3 H,
73.50, H 4.93, N 6.86%. 1H NMR (CDCl3): δ = 7.97 (dd 1.5 Hz,
7.8 Hz, 1 H, aryl), 7.83 (m, 1 H, aryl), 7.70 (d 5.4 Hz, 1 H, aryl), 7.56–
7.51 (mm, 5 H, aryl), 7.27 (mm, 7 H, aryl), 7.15–7.09 (m, 1 H, aryl),
6.82–6.76 (mm, 2 H, aryl), 5.41 (s, 2 H, CH2). 13C NMR (CDCl3): δ
aryl), 6.95–6.86 (mm, 2 H, aryl), 5.11 (s, 2 H, CH2), 0.45 (s, 6 H, = 170.7 (C=O), [157.3, 154.7, 144.4, 140.5, 139.9, 133.7, 133.5, 129.5,
6
www.zaac.wiley-vch.de © 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Z. Anorg. Allg. Chem. 0000, 0–0

Job/Unit: Z12084
/KAP1
Date: 20-06-12 16:58:28
Pages: 9
Pentacoordinate Silicon Complexes with N-(2-pyridylmethyl)salicylamide
128.6, 127.7, 123.2, 121.4, 120.1, 119.8, 119.1 (aryl)], 47.7 (CH2). 29Si
NMR (CDCl3): δ = –81.2, (CP/MAS): δiso = –88.8 ppm.
140.5, 139.7, 134.5, 133.6, 129.5, 128.5, 123.3, 121.2, 120.2, 119.6,
119.0, 113.3 (aryl, allyl C=C)], 48.0 (N-CH2), 30.2 (allyl CH2). 29Si
NMR (CDCl3): δ = –74.2, (CP/MAS): δiso = –77.2 ppm.
Crystal Structure Analysis of 2c: Single crystals were obtained di-
rectly from the synthesis. C25H20N2O2Si, Mr = 408.52, T = 150(2) K, Crystal Structure Analysis of 2e: Single crystals were obtained di-
monoclinic, space group P21/n, a = 15.2057(3), b = 14.7503(3), c = rectly from the synthesis. C22H20N2O2Si, Mr = 372.49, T = 150(2) K,
27.2041(5) Å, β = 100.592(1)°, V = 5997.6(2) Å3, Z = 12, ρcalcd.
=
triclinic, space group P1, a = 9.8407(2), b = 9.9004(2), c =
¯
1.357 Mg·m–3, μ(Mo-Kα) = 0.143 mm–1, F(000) = 2568, 2θmax = 50.0°, 10.7876(2) Å, α = 93.128(1), β = 91.212(1), γ = 117.923(1)°, V =
55511 collected reflections, 10433 unique reflections (Rint = 0.0391), 925.96(3) Å3, Z = 2, ρcalcd. = 1.336 Mg·m–3, μ(Mo-Kα) = 0.147 mm–1,
811 parameters, S = 1.073, R1 = 0.0419, wR2 = 0.1037 [I Ͼ 2σ(I)], R1 F(000) = 392, 2θmax = 60.0°, 21179 collected reflections, 5323 unique
= 0.0729, wR2 = 0.1139 (all data), max./min. residual electron density
+0.354/–0.271 e·Å–3.
reflections (Rint = 0.0257), 263 parameters, S = 1.061, R1 = 0.0374,
wR2 = 0.0984 [I Ͼ 2σ(I)], R1 = 0.0487, wR2 = 0.1034 (all data), max./
min. residual electron density +0.420/–0.264 e·Å–3.
Synthesis of Compound 2d: A solution of ligand 1 (1.23 g,
5.70 mmol) and triethylamine (1.73 g, 6.30 mmol) in THF (20 mL) Synthesis of Compound 2f:
A solution of ligand 1 (1.00 g,
was stirred at room temperature and a solution of dibenzyldichlorosil-
ane[6a] (1.76 g, 6.30 mmol) in THF (10 mL) was added within 10 s.
The mixture was stirred for 2 h, whereupon the hydrochloride precipi-
tate was filtered off and washed with THF (10 mL). From the com-
bined filtrate and washings the solvent was removed under reduced
pressure and the resultant brownish oily residue was dissolved in warm
toluene (1 mL) and the solution was stored at –25 °C for crystalli-
4.63 mmol) and triethylamine (1.41 g, 13.9 mmol) in THF (30 mL)
was stirred at room temperature and phenyldichlorosilane (1.10 g,
5.10 mmol) was added within 10 s. The mixture was stirred for 2 h,
whereupon the hydrochloride precipitate was filtered off and washed
with THF (10 mL). From the combined filtrate and washings the sol-
vent was removed under reduced pressure and the resultant brownish
oily residue was dissolved in a mixture of toluene (1.5 mL) and THF
zation. After 4 weeks the beige crystals were filtered off, washed with (2 mL) and the solution was stored at room temperature for crystalli-
9 mL of toluene and dried in vacuo. Yield 1.27 g (2.91 mmol, 65%). zation. After 2 days the colorless crystals were filtered off, washed
M.p. 135 °C, Anal. found: C 73.93, H 5.33, N 6.36%, calcd. for with 6 mL of a mixture of toluene and THF (1:1) and briefly dried in
C27H24N2O2Si: C 74.28, H 5.54, N 6.42%. 1H NMR (CDCl3): δ =
8,42 (d 5.4 Hz, 1 H, aryl), 7.95 (d 7.9 Hz, 1 H, aryl), 7.82 (m, 1 H,
vacuo. The product crystallized as the solvate 2f·THF (according to
single crystal structure analysis and H NMR spectroscopic data of a
1
aryl), 7.42 (t, 7.9 Hz, 1 H, aryl), 7.35 (m, 1 H, aryl), 7.16 (d 8.1 Hz, sample prepared immediately after isolating the solid product). Yield
1 H, aryl), 6.99–6.86 (mm, 7 H, aryl), 6.80 (d 8.2 Hz, 1 H, aryl), 6.70 2.11 g (5.22 mmol, 62%). Anal. found: C 68,26, H 5.15, N 8.72%.
(d 6.6 Hz, 4 H, aryl), 4.37 (s, 2 H, N-CH2), 2.68 (d 13.1 Hz, 2 H, This composition hints at loss of solvent during preparation of the
SiCH2), 2.49 (d 13.1 Hz, 2 H, SiCH2). 13C NMR (CDCl3): δ = 169.9 sample, as it corresponds to the values calculated for the solvent free
(C=O), [157.5, 155.5, 142.8, 139.5, 139.0, 133.5, 129.5, 128.3, 127.9,
product. Calcd. for C23H24N2O3Si: C 68.29, H 5.98, N 6.92%, calcd.
1
124.3, 123.1, 121.2, 119.9, 119.3, 119.0 (aryl)], 47.2 (N-CH2), 30.2 for C19H16N2O2Si: C 68.65, H 4.85, N 8.43%. H NMR (CDCl3): δ
(SiCH2). 29Si NMR (CDCl3): δ = –66.2, (CP/MAS): δiso = –71.3 ppm.
= 8.15 (d 5.9 Hz, 1 H, aryl, 8.00–7.94 (mm, 2 H, aryl), 7.59 (d 7.8 Hz,
1 H, aryl), 7.40 (t 6.6 Hz, 1 H, aryl), 7.36–7.25 (mm, 3 H, aryl), 7.21–
7.14 (mm, 3 H, aryl), 6.85 (mm, 2 H, aryl), 5.88 (s, 1 H, Si-H; with
29Si-satellites of 1J 290 Hz), 5.31 (d 20.5 Hz, 1 H, CH2), 5.18 (d
20.5 Hz, 1 H, CH2). 13C NMR (CDCl3): δ = 170.5 (C=O), [157.4,
154.1, 141.9, 140.6, 133.7, 133.6, 129.7, 129.0, 127.8, 124.1, 121.9,
119.8 (2x), 119.2 (aryl)], 48.3 (CH2). 29Si NMR (CDCl3): δ = –90.7
(1J SiH = 290 Hz), (CP/MAS): δiso = –94.2 ppm.
Crystal Structure Analysis of 2d: Single crystals were obtained di-
rectly from the synthesis. C27H24N2O2Si, Mr = 436.57, T = 100(2) K,
orthorhombic, space group Pna21, a = 8.7355(2), b = 19.3266(4), c =
13.0917(2) Å, V = 2210.24(8) Å3, Z = 4, ρcalcd. = 1.312 Mg·m–3, μ(Mo-
Kα) = 0.134 mm–1, F(000) = 920, 2θmax = 64.0°, 30364 collected re-
flections, 7551 unique reflections (Rint = 0.0317), 289 parameters, S =
1.033, χ(Flack) = 0.02(7), R1 = 0.0328, wR2 = 0.0792 [I Ͼ 2σ(I)], R1
= 0.0386, wR2 = 0.0820 (all data), max./min. residual electron density
+0.302/–0.194 e·Å–3.
Crystal Structure Analysis of 2f·THF: Single crystals were obtained
directly from the synthesis. C23H24N2O3Si, Mr = 404.53, T = 100(2)
K, monoclinic, space group P21/c, a = 14.9381(3), b = 8.8942(2), c =
15.4527(3) Å, β = 105.488(1)°, V = 1978.53(7) Å3, Z = 4, ρcalcd.
=
Synthesis of Compound 2e:
A solution of ligand 1 (1.00 g,
1.358 Mg·m–3, μ(Mo-Kα) = 0.147 mm–1, F(000) = 856, 2θmax = 70.0°,
29248 collected reflections, 8701 unique reflections (Rint = 0.0369),
266 parameters, S = 1.084, R1 = 0.0410, wR2 = 0.1074 [I Ͼ 2σ(I)], R1
= 0.0640, wR2 = 0.1156 (all data), max./min. residual electron density
+0.524/–0.309 e·Å–3.
4.63 mmol) and triethylamine (1.41 g, 13.9 mmol) in THF (30 mL)
was stirred at room temperature and allylphenyldichlorosilane (1.10 g,
5.10 mmol) was added within 10 s. The mixture was stirred for 2 h,
whereupon the hydrochloride precipitate was filtered off and washed
with THF (10 mL). From the combined filtrate and washings the sol-
vent was removed under reduced pressure and the resultant brownish
oily residue was dissolved in chloroform (5 mL) and the solution was 3a, 3b, 3c: The syntheses of 3b and 3c are reported in reference [9a],
stored at room temperature for crystallization. After 3 d the beige crys-
tals were filtered off, washed with 3 mL of chloroform and dried in
vacuo. Yield 1.19 g (5.88 mmol, 66%). M.p. 226 °C, Anal. found: C
70.92, H 5.41, N 7.48%, calcd. for C22H20N2O2Si: C 70.94, H 5.41,
N 7.52%. 1H NMR (CDCl3): δ = 7.96 (m, 1 H, aryl), 7.90–7.84 (mm,
and compound 3a was synthesized in analogy: To a solution of N-
benzyl-2-hydroxyacetophenoneimine (0.20 g, 0.89 mmol) and triethyl-
amine (0.25 g, 2.5 mmol) in THF (10 mL) dimethyldichlorosilane
(0.13 g, 1.0 mmol) was added at room temperature, whereupon triethyl-
amine hydrochloride precipitated immediately and the initially yellow
2 H, aryl), 7.39 (d 7.8 Hz, 1 H, aryl), 7.37 (mm, 2 H, aryl), 7.30–7.10 solution turned colorless. The mixture was stored at 6 °C for 30 min,
(mm, 5 H, aryl), 6.78 (mm, 2 H, aryl), 5.85 (m, 1 H, CH2–CH=CH2), finally the hydrochloride was filtered off and from the filtrate the vola-
5.48 (d 19.5 Hz, 1 H, NCH2), 4.90 (d 19.5 Hz, 1 H, NCH2), 4.59 [d tiles (THF, excess Et3N and Me2SiCl2) were removed in vacuo to yield
10.2 Hz, 1 H, CH2–CH=CHH(E)], 4.31 [d 17.2 Hz, 1 H, CH2–
CH=CHH(Z)], 2.39 (m, 1 H, CH2–CH=CH2), 1.88 (m, 1 H, CH2–
an almost colorless oil of 3a (0.24 g, 0.85 mmol, 96%). 1H NMR
(CDCl3): δ = 7.55 (dd, 8.0 Hz, 1.5 Hz, 1 H, aryl), 7.15–7.35 (mm, 6 H,
CH=CH2). 13C NMR (CDCl3): δ = 170.5 (C=O), [157.6, 155.5, 143.3, aryl), 6.85–6.95 (mm, 2 H, aryl), 4.54 (d, 1.3 Hz, 1 H, C=CH2), 4.43
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
7

Job/Unit: Z12084
/KAP1
Date: 20-06-12 16:58:28
Pages: 9
D. Schwarz, E. Brendler, E. Kroke, J. Wagler
ARTICLE
Ceram. Soc. Jpn. 2006, 114, 567–570; c) S. Nahar-Borchert, E.
Kroke, R. Riedel, B. Boury, R. J. P. Corriu, J. Organomet. Chem.
2003, 686, 127–133; d) D. S. Kim, E. Kroke, R. Riedel, A. O.
Gabriel, S. C. Shim, Appl. Organomet. Chem. 1999, 13, 495–499.
[7] G. W. Fester, J. Wagler, E. Brendler, U. Böhme, D. Gerlach, E.
Kroke, J. Am. Chem. Soc. 2009, 131, 6855–6864.
(d, 1.3 Hz, 1 H, C=CH2), 3.86 (s, 2 H, N-CH2), 0.34 (s, 6 H, Si–CH3).
13C NMR (CDCl3): δ = 151.0 (C–O), 145.8 (C=C–N), 138.3, 129.5,
128.4, 127.1, 126.6, 126.4, 124.7, 121.4, 120.1, 85.1 (C=CH2), 47.9 (N–
CH2), –1.0 (Si–CH3). 29Si NMR (CDCl3): δ = 2.8 ppm.
[8] According to a search of the Cambridge Crystal Structure Data
Base, February 2012, ConQuest version 1.14, searching for the
general pyridine core, N···Si bound (type “any bond”) to a SiC2
fragment.
Acknowledgements
We gratefully acknowledge the NMR spectroscopy service performed
by DI(FH) Beate Kutzner, DC Conny Wiltzsch and DC Katrin Lippe
(Institut für Anorganische Chemie, TU Bergakademie Freiberg).
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Roewer, Z. Naturforsch. 2005, 60b, 1054–1064; b) E. Brendler,
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[10] a) T. K. Prakasha, A. Chandrasekaran, R. O. Day, R. R. Holmes,
Inorg. Chem. 1996, 35, 4342–4346; b) E. Gómez, V. Santes, V.
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Received: February 28, 2012
Published Online: ᭿
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Job/Unit: Z12084
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Date: 20-06-12 16:58:28
Pages: 9
Pentacoordinate Silicon Complexes with N-(2-pyridylmethyl)salicylamide
D. Schwarz, E. Brendler, E. Kroke, J. Wagler* ............... 1–9
Pentacoordinate Silicon Complexes with N-(2-pyridylmethyl)-
salicylamide as a Dianionic (ONNЈ) Tridentate Chelator
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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