Amino Acid Functionalized Organotin Trichlorides and Their Tin Sulfide Clusters

Article abstract of DOI:10.1002/ejic.201900528

We present a new synthesis of functionalized tin sulfide clusters via organotin trichlorides with boc-protected amino acids (R^AAcSnCl₃). In this work we used non-polar (alanine, valine, leucine, phenylalanine and methionine), polar/neutral (serine and tyrosine) and basic (histidine) amino acids. We obtained single crystals from a Boc-protected valine derivative of the originally used organotin trichloride R¹SnCl₃ [R¹ = CMe₂CH₂C(O)Me] and determined its structure by means of X-ray diffraction. A subsequent reaction with sulfide sources led to a variety of respective cluster structures. By using either (Me₃Si)₂S or Na₂S, the reaction product turns out to be the defect-heterocubane cluster [(R^AAcSn)₃S₄Cl] or the “doppeldecker”-type cluster [(R^AAcSn)₄S₆], respectively, according to ¹¹⁹Sn NMR spectroscopy.

Full text of DOI:10.1002/ejic.201900528

A Journal of
Accepted Article
Title: Amino Acid-Functionalized Organotin Trichlorides and Their Tin
Sulfide Clusters
Authors: Annikka Engel and Stefanie Dehnen
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10.1002/ejic.201900528
European Journal of Inorganic Chemistry
FULL PAPER
Amino Acid-Functionalized Organotin Trichlorides and Their Tin
Sulfide Clusters
Annikka Engel[a] and Stefanie Dehnen*[a]
Abstract: We present a new synthesis of functionalized tin sulfide
clusters via organotin trichlorides with boc-protected amino acids
(RAAcSnCl3). In this work we used non-polar (alanine, valine, leucine,
phenylalanine and methionine), polar/neutral (serine and tyrosine)
and basic (histidine) amino acids. We were able to obtain single
crystals from a boc-protected valine derivative of the originally used
sulfide clusters by an amino acid derivatives (AAc; equation 1),
and second, cluster formation under employment of
corresponding bio-organotin trichloride reactants (equation 2).
A2S may be any source of sulfide.
organotin trichloride R1SnCl3 (R1
= CMe2CH2C(O)Me), and
determined its structure by means of X-ray diffraction. A subsequent
reaction with sulfide sources led to a variety of respective cluster
structures. By using either (Me3Si)2S or Na2S, the reaction product
turns out to be the defect-heterocubane cluster [(RASSn)3S4Cl] or the
“doppeldecker”-type cluster [(RASSn)4S6], respectively, according to
119Sn NMR spectroscopy.
In previous works, the syntheses of organotin sulfide clusters
were generally carried out according to the post-functionalization
route sketched in equation 1.[7] However, upon addition of amino
acid derivatives being added, this led to intramolecular
condensation reactions between the keto-functionalized
substituent R1 at one cluster Sn atom and a terminal amine group
at the amino acid attached to R1 at another cluster Sn atom.[18]
To suppress reactions of this kind, we decided to make use of
boc-protection of the amino group during the cluster formation,
which is presented herein. Boc-protected amino acid hydrazides
are prepared according to literature starting from the boc-
protected amino acid methyl ester which is reacted with
hydrazine hydrate in methanol.[20] Besides this variation of
equation 1, we also report a new versatile synthesis route
according to equation 2, in which the keto group of the R1 ligand
is reacted prior to the cluster synthesis, hence before any further
condensation reaction is going to take place.
Introduction
Chalcogenidometallate clusters provide a perspective into a wide
field of applications,[1-3] Some organotetrel chalcogenide clusters
that combine tetrel atoms Si, Ge, or Sn and chalcogen atoms S,
Se, or Te with different organic substituents R, for instance, show
extreme nonlinear optical properties.[4,5] Such clusters have been
isolated in many different inorganic core architectures, with the
most dominant ones possessing a defect-heterocubane-type
[(RSn)3S4Cl], a “doppeldecker”-type [(RSn)4S6], and the isomeric
adamantane-type structure [(RSn)4S6], respectively.[5-13]
Metalchalcogenide clusters furthermore play an important role
for bio-relevant developments.[14] Here, tin sulfide clusters can be
potentially useful as cytotoxic agents, as they decompose under
slightly acidic conditions to release cytotoxic H2S.[15] This may
allow for a targeted delivery of H2S to undesirable cells, the
environment of which can be more acidic than that of healthy
cells.[16] However, for this, it will be necessary to (a) make the
clusters bio-compatible regarding solubility and transport
through membranes, and (b) to provide a platform for a potential
attachment of specific units for bio-recognition.
Results and Discussion
With the intention to pursue a reaction strategy according to
equation 1, the pre-functionalized cluster [(R1Sn)3S4Cl] was
prepared according to literature, by reaction of 4-methyl-4-
(trichlorostannyl)pentane-2-one with 1.30 eq of (Me3Si)2S.[21]
However, it is known that the reaction does not proceed
quantitatively, which leads to a mixture of side products and
remaining starting material,[7] so addition of boc-protected valine
hydrazide in the second step allowed for a side reaction with the
starting material to take place. Crystals of RBocValSnCl3 (1; RBocVal
= CMe2CH2C(NNHBocVal)Me) were obtained after storage for
several months at room temperature. The compound crystallizes
in a mixture of the enantiopure crystals in the tetragonal space
groups P41212 and P432121, respectively (Z = 8). Figure 1 (top)
depicts the molecular structure of the species that crystallized in
P41212. The Sn atom in 1 possesses a distorted octahedral
coordination environment due to the back-coordination of the
organic ligand via Sn1···O1 (2.202(7) Å) and Sn1···N1
(2.265(9) Å). The Sn–Cl bond lengths range from 2.367(3) to
2.523(3) Å which is naturally slightly longer than in the keto-
functionalized, four-coordinate organotin trichloride (2.3286(7) –
2.3866(8) Å),[22] but similar to distances in other RSnCl3 species
Beyond this background, we are currently interested in the
formation of tin sulfide clusters with bio-organic decoration to
enable a more targeted study under physiological conditions.[17-
19]
For reaching this goal two strategies are generally feasible:
First, post-functionalization of pre-functionalized organotin
[a]
A. Engel, Prof. Dr. S. Dehnen
Fachbereich Chemie and Wissenschaftliches Zentrum für
Materialwissenschaften (WZMW)
Philipps-Universität Marburg
Hans-Meerwein-Straße 4, 35043 Marburg
E-mail: dehnen@chemie.uni-marburg.de
Homepage: https://www.uni-marburg.de/fb15/ag-dehnen
Supporting information for this article is given via a link at the end of
the document.
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10.1002/ejic.201900528
European Journal of Inorganic Chemistry
FULL PAPER
with coordination numbers larger than four (2.3601(12) to
2.5484(129 Å).[19] The elongation of the Sn1-Cl3 bond arises from
One of the products of these reactions, compound 2, was
obtained in single-crystalline form. Like compound 1, it also
crystallizes in a mixture of enantiopure crystals in the tetragonal
space groups P412121 and P432121 (Z = 8), shown for the other
enantiomer that crystallized in P432121 in Figure 1 (bottom).
an intermolecular Cl···H-N coordination and
a Cl···H-C
coordination with one methyl substituent of the valine side chain.
The isolation of 1 prompted us to change the synthesis strategy
towards the route according to equation 2, and to extend this
approach to various amino acids. The hydrazide-functionalized
amino acids are subsequently reacted with 4-methyl-4-
(trichlorostannyl)pentane-2-one to form the corresponding
organotin trichlorides, RBocValSnCl3 (1), RBocAlaSnCl3 (2),
RBocLeuSnCl3,(3), RBocPheSnCl3 (4), RBocMetSnCl3 (5), RBocSerSnCl3
(6), RBocTyrSnCl3 (7), and RBocHisSnCl3 (8).
The general synthesis route is illustrated in Scheme 1, and the
products are summarized in Scheme 2. All compounds were
characterized by means of NMR spectroscopy and ESI(–) mass
spectrometry.
Figure 1. Molecular structures (ball-and-stick models) of RBocValSnCl3
(1; RBocVal = CMe2CH2C(NNHBocVal)Me and RBocAlaSnCl3 (2;
RBocAla = CMe2CH2C(NNHBocAla)Me).
Non-relevant
hydrogen
atoms are omitted for clarity. Intramolecular coordination of N and O
donor atoms to the central Sn atom are indicated by blue dashed
lines, intramolecular hydrogen bonds are indicated by pink dashed
lines.
As in 1, the tin atom is situated in a slightly distorted octahedral
environment. Sn–Cl bond length vary from 2.372(3) to 2.439(4)
Å. This is shorter on average than in the valine derivative, which
may be explained by replacement of intermolecular interactions
involving the Cl– ligands in 1 (see Figure 2) by intramolecular
Cl···H interactions. Similarly, the Sn···N (2.190(8) Å) and the
Sn···O bond lengths (2.223(8) Å) are inverted with regard to the
situation in 1. Two chlorine atoms form intramolecular hydrogen
bonds with the terminal methyl groups, as indicated by dashed
lines in Figure 1.
Scheme 1. Synthesis route for the preparation of amino acid
functionalized tin sulfide clusters. In the first step, a boc-protected
amino
acid
hydrazide
is
reacted
with
4-methyl-4-
(trichlorostannyl)pentane-2-one to yield the corresponding organotin
trichloride RAAcSnCl3, which is subsequently reacted with (Me3Si)2S
in DCM or with Na2S in acetone to form tin sulfide clusters of the
general formula [(RAAcSn)3S4Cl] or [(RAAcSn)4S6], respectively.
Figure 2. Section of the crystal structure of compound 1, indicating
the existence of intermolecular hydrogen bonding (pink dashed
lines).
Scheme 2. Boc-protected amino acid-functionalized organotin
trichlorides RBocValSnCl3 (1), RBocAlaSnCl3 (2), RBocLeuSnCl3 (3),
RBocPheSnCl3 (4), RBocMetSnCl3 (5), RBocSerSnCl3 (6), RBocTyrSnCl3 (7),
and RBocHisSnCl3 (8).
Characterization of 1 – 8 by means of 1H NMR spectroscopy
shows that upon attachment to R1SnCl3, the methine groups
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10.1002/ejic.201900528
European Journal of Inorganic Chemistry
FULL PAPER
(CH) and the NH protons of the amino acid substituent are
slightly shifted downfield compared to the boc-protected amino
acid hydrazide reactant. In a few cases (2, 4 and 8), the NH
protons are not observable due to solvent effects. The methyl
and methylene groups of the R1 part of the RAAc substituent are
shifted highfield compared to the keto-functionalized organotin
trichloride reactants. The signals of the methyl groups on the boc
protection group and the signals of the side chains of the amino
acid show marginal deviations only from with those of the starting
materials. The only significant observation in the NMR spectra is
made in case of the reaction with boc-protected cysteine. Here,
spectroscopy and mass spectrometry. Up to date, we have not
been able to grow single-crystals of any of the products, even at
lower temperature, which we ascribe to the extremely high
flexibility of the substituents. 1H and 13C NMR spectroscopy
indicates that the organic substituent stays intact during the
reaction with (Me3Si)2S. 119Sn NMR spectra of the tin sulfide
clusters shows two signals, one at around –60 and a second one
at around –90 ppm. Both signals are shifted downfield as
compared to those of the corresponding organotin trichlorides.
The signal at –60 ppm is most probably assigned to the Sn atom
carrying an additional Cl substituent owing to the higher extent
of deshielding. A second batch of signals for the organic
substituent attached to this very Sn atom is not observed in the
1H or 13C NMR spectra, most probably, as the electronic effect is
not distinct enough here.
For getting more information about the cluster compositions, the
products were additionally studied by ESI(+) mass spectrometry
The mass spectra indeed prove clean formation of the clusters,
showing up as fragments upon release of the chloride substituent,
[M–Cl]+ = [(RAAcSn)3S4]+, with almost no fragments. However, the
spectra further indicate that amino acid substituents with alcohol
groups in their side chains undergo a side reaction with Me3SiCl
released during the cluster formation reaction (see Scheme 1),
which is a common reactant for alcohol group protection under
formation of HCl. Therefore, for the clusters terminated by boc-
protected serine (14) and tyrosine (15), the product tin sulfide
clusters comprise three silyloxyl groups (Figure 3).
1
the H NMR spectrum gave no evidence for product formation,
so we assume that organotin trichloride was decomposed by
reaction with the thiol side group. We therefore reacted the
methionine derivative, the thiole group of which is protected by a
methyl substituent. This reaction took place as expected, thereby
confirming our assumption. ESI(–) mass spectra of compounds
1 – 8 show the molecular peaks after deprotonation and
additional release of 1-2 equivalents of HCl (see Supporting
Information).
For the subsequent cluster synthesis of defect-heterocubane-
type clusters of the formula [(RAAcSn)3S4Cl] (9 – 16), the
functionalized organotin trichlorides 1 – 8 were reacted with
1.30 eq of (Me3Si)2S, which accords with the common synthesis
of the defect-heterocubane-type cluster.[7] Increasing the amount
of (Me3Si)2S only leads to a higher yield. The solvent can be
either dichloromethane or toluene, which does not affect yield or
purity of the products. The products were characterized by NMR
Figure 3. ESI(+) mass spectrum of a fresh solution of compound 15 in DCM. The main signal at m/z = 1830.3927 corresponds to the sum
formula [C69H114N9O12Si3S4Sn3]+. The alcohol function of the amino acid side chain was silylated by the Me3Si group from (Me3Si)2S or Me3SiCl.
A structural diagram is suggested in the inset.
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10.1002/ejic.201900528
European Journal of Inorganic Chemistry
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Reactions of compounds 1 – 3 with 1.00 eq of Na2S in an
acetone water mixture at –10 °C served to prepare clusters
with “doppeldecker”-type structure, [(RAAcSn)4S6] (17 – 19). In
contrast to the synthesis of the related keto-functionalized
compound [R1Sn)4S6], which precipitates after a few minutes
from the reaction solution,[23] the clusters equipped with RAAc
ligands do not precipitate at all. For this, the solvent was
removed in vacuo, whereupon a colorless solid was obtained
in all cases. The products were re-dissolved in DCM to
separate them from sodium chloride, which precipitates during
the reaction with Na2S. Mass spectra of these solutions
informed about the chemical composition of the products.
1H and 13C NMR spectra show that the organic substituent is
not decomposed; yet, the spectra give no information about
the cluster type. The chemical shifts of the signals are almost
identical with those observed for the defect-heterocubane-type
clusters (9 – 16). 119Sn NMR spectra, however, are clearly
different. They exhibit relatively broad signals between –113
and –116 ppm. The signal width is in agreement with highly
mobile substituents, and the appearance of one main signal
each corresponds with the expectations according with the
chemical equivalence of the tin atoms. Minor signals that
appear downfield-shifted by about 50 ppm, between –43 and
–62 ppm, indicate a partial change in the ligand conformation
and corresponding loss of the back-coordination, such as
reported in previous studies.[23] In summary, the 119Sn NMR
spectra of the two cluster types possess signals at distinctly
different chemical shifts (see Supporting Information), with the
major signals of compounds 17 – 19 being shifted upfield in
comparison to those of compounds 9 – 16.
In agreement with previous works on clusters of the general
formula [(RSn)4Sn6] that adopted the “doppeldecker”-type
structure,[24] the ESI(+) mass spectra indicate
a re-
organization of the structure under ESI-MS conditions: the m/z
values accord with formulae that can be assigned to tin sulfide
clusters possessing a defect-heterocubane-type core. Figure
4 shows the EIS(+) mass spectrum of a fresh solution of
compound 18 in DCM as an example.
Figure 4. ESI(+) mass spectrum of a fresh solution of compound 18 in DCM. The main signal at m/z = 1464.3310 corresponds to a species
with the sum formula [C51H96N9O9S4Sn3]+. The spectrum accords with a defect-heterocubane-type cluster, hence indicates a re-organization
of the inorganic core from [Sn4S6] to [Sn3S4], which was previously observed for related clusters with other organic ligands. A structural
diagram is suggested in the inset.
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10.1002/ejic.201900528
European Journal of Inorganic Chemistry
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Synthesis of BocValN2H3 (a): 1.00 mL (4.60 mmol, 1.00 eq) of boc-
protected L-valine methylester were dissolved in 10 mL methanol and
0.9 mL (13.8 mmol, 3.00 eq) were added at room temperature and stirred
overnight. The solvent was removed under reduced pressure and a
colorless solid was obtained.
Conclusions
Herein, we present a new route into amino acid-functionalized
organotin trichlorides RAAcSnCl3, by condensation of 4-methyl-4-
(trichlorostannyl)pentane-2-one with a variety of amino acid
hydrazides, and their follow-up reactions towards bio-organo-
functionalized tin sulfide clusters. We were able to obtain eight
different organotin trichlorides and characterize them by means of
NMR spectroscopy and mass spectrometry, as well as by single-
crystal X-ray diffraction for the underlying amino acids being
valine and alanine. By subsequent reactions of these compounds
with (Me3Si)2S or Na2S, we selectively generated clusters with the
sum formulae [(RAAcSn)3S4Cl] or [(RAAcSn)4S6], respectively.
These clusters were characterized by 1H and 13C NMR
spectroscopy as well as by mass spectrometry. As the highly
flexible bio-organic substituents prohibited the formation of single-
crystals under the given reaction conditions, the type of the cluster
core was determined by means of 119Sn NMR spectroscopy.
Future work will point into two directions. We will first address de-
protection of the amino acid termini of the ligands and their
subsequent reactions with activated amino acids to grow
oligopeptides for better fit to physiological conditions. Second, we
aim at hydrolysis studies under various physiological conditions
to study the targeted release of H2S.
1H NMR DMSO-d6, 300 MHz, δ (ppm): 9.01 (s, 1H, NH), 7.15 (d, 3J = 8.2
Hz, NH), 6.61 (d, 3J = 8.8 Hz, 1H, NH), 4.22 (s, 2H, NH2), 3.88-3.64 (m,
1H, CH), 2.05-1.78 (m, 1H, CH), 1.37 (s, 9H, CH3), 0.83 (ddd, 4J = 13.8 Hz,
3J = 6.7 Hz, 3J = 3.4 Hz, 6H, CH3). 13C NMR DMSO-d6, 75 MHz, δ (ppm):
170.6 (Cquart), 155.2 (Cquart), 77.8 (Cquart), 59.3 (CH), 58.5 (CH), 30.4 (CH),
28.1 (CH3), 19.1 (CH3), 18.4 (CH3).
Synthesis of BocAlaN2H3 (b): 1.00 g (4.90 mmol, 1.00 eq) of boc-
protected L-alanine methylester were dissolved in 10 mL methanol and
0.9 mL (14.76 mmol, 3.00 eq) of hydrazine hydrate (80% in methanol)
were added. The solution was stirred overnight, the solvent evaporated
under reduced pressure and a colorless solid was obtained.
1H NMR DMSO-d6, 300 MHz, δ (ppm): 8.96 (s, 1H, NH), 6.82 (d,
3J = 7.5 Hz, 1H, NH), 4.18 (s, 2H, NH2), 3.97-3.85 (m, 1H CH), 1.36 (s, 9H,
CH3) 1.14 (d, 3J = 7.1 Hz, CH3). 13C NMR DMSO-d6,75 MHz, δ (ppm):
172.1 (Cquart), 154.9 (Cquart), 77.9 (Cquart), 48.3 (CH), 28.2 (CH3), 18.4 (CH3).
Synthesis of BocLeuN2H3 (c): 1.00 g (4.07 mmol, 1.00 eq) of boc-
protected L-leucine methylester were dissolved in 10 mL of methanol and
0.8 mL (12.23 mmol, 3.00 eq) of hydrazine hydrate (80% in methanol)
were added. The solution was stirred overnight, the solvent evaporated
under reduced pressure and a colorless solid was obtained.
1H NMR DMSO-d6, 300 MHz, δ (ppm): 9.01 (s, 1H, NH), 6.77 (d,
3J = 8.4 Hz, 1H, NH), 4.18 (s, 2H, NH2), 3.92 (dd, 2J = 14.5 Hz, 3J = 8.8 Hz,
1H, CH), 3.61 (s, 1H, CH), 1.62-1.46 (m, 1H, CH), 1.36 (s, 9H, CH3), 0.89-
0.80 (m, 6H, CH3). 13C NMR DMSO-d6, 75 MHz, δ (ppm): 171.7 (Cquart),
77.8 (Cquart), 51.6 (CH), 51.3 (CH), 41.1 (Cquart), 28.2 (CH3), 24.2 (CH), 22.8
(CH3), 21.6 (CH3).
Experimental Section
Reactions of products containing metal atoms were performed under Ar
atmosphere with Schlenk techniques. All solvents were dried and freshly
distilled or degassed prior to use and stored over 3 Å molecular sieve.
Nuclear magnetic resonance spectroscopy: 1H NMR (300 MHz) and
13C NMR (75 MHz) measurements were carried out using a Bruker AV II
spectrometer at 25 °C. 1H NMR (500 MHz), 13C NMR (126 MHz) and119Sn
NMR (187 MHz) measurements were carried out using a Bruker AV III HD
spectrometer at 25 °C. Note that only 13C{1H} experiments were carried
out in this work. Chemical shifts (δ) are given in ppm relative to the
respective solvent residual peaks: Acetone-d6: δ = 2.05 and
29.84/206.26 ppm; CDCl3: δ = 7.26 and 77.16 ppm; CD2Cl2: δ = 5.32 and
53.84 ppm; DMSO-d6: δ = 2.50 and 39.52 ppm. Data are reported as
follows: multiplicity s = singlet, d = doublet, t = triplet, q = quartet, m =
multiplet, br = broad, or combinations thereof.
Synthesis of BocPheN2H3 (d): 1.00 g (3.58 mmol, 1.00 eq) of boc-
protected L-phenylalanine methylester were dissolved in 10 mL methanol
and 0.7 mL (10.78 mmol, 3.00 eq) of hydrazine hydrate (80% in methanol)
were added. The solution was stirred overnight, the solvent evaporated
under reduced pressure and a colorless solid was obtained.
1H NMR DMSO-d6, 300 MHz, δ (ppm): 9.10 (s, 1H, NH), 7.31-7.13 (m, 5H,
Harom.), 6.89 (d, 3J = 8.7 Hz, 1H NH), 4.23 (s, 2H, NH2), 4.10 (td, 3J = 9.4 Hz,
3J = 4.9 Hz, 1H, CH), 2.80 (ddd, 2J = 23.5 Hz, 2J = 13.5 Hz, 3J = 7.5 Hz,
2H, CH2), 1.29 (s, 9H, CH3). 13C NMR DMSO-d6, 75 MHz, δ (ppm): 170.9
(Cquart), 138.1 (Cquart), 129.1 (Carom.), 128.0 (Carom.), 126.1 (Carom.), 77.8
(Cquart), 54.38 (CH), 37.79 (CH2), 28.1 (CH3).
Mass spectrometry: ESI(+)- and ESI(–)-MS measurements were carried
out using a LTQ-FT Ultra from Thermo Fischer Scientific with syringe pump
infusion method.
Synthesis of BocMetN2H3 (e): 2.74 g (10.42 mmol, 1.00 eq) of boc-
protected L-phenylalanine methylester were dissolved in 30 mL methanol
and 1.0 mL (31.26 mmol, 3.00 eq) of hydrazine hydrate (80% in methanol)
were added. The solution was stirred overnight and the solvent removed
in vacuo to afford a colorless powder.
X-ray diffractometry: Data collection was performed on a STOE IPDS 2
diffractometer using MoKα radiation (λ = 71.073 pm) at 100 K and on a
STOE StadiVari diffractometer CuKα radiation (λ = 154.186 pm) at 230 K.
Structure solution and refinement was done by direct methods and full-
matrix-least-squares on F2, respectively, using SHELXTL software.[25]
Details of the measurements, structure solutions, and refinements are
summarized in Table S1 in the Supporting Information. CCDC 1915264-
1915265 contain the supplementary crystallographic data for this paper.
These data are provided free of charge by The Cambridge
Crystallographic Data Centre.
1H NMR DMSO-d6, 300 MHz, δ (ppm): 9.02 (s, 1H, NH), 6.90 (d,
3J = 8.0 Hz, 1H, NH), 4.22 (s, 2H, NH2), 3.96 (dd, 2J = 14.1 Hz, 3J = 7.6 Hz,
1H, CH), 3.32 (s, 1H, CH), 2.39-2.31 (m, 2H, CH2), 2.02 (s, 3H, CH3), 1.83-
170 (m, 2H, CH2), 1.37 (s, 9H, CH3). 13C NMR DMSO-d6, 75 MHz, δ (ppm):
171.0 (Cquart.), 155.2 (Cquart.), 78.9 (Cquart.), 52.2 (CH), 32.0 (CH3), 29.6
(CH2), 28.2 (CH3), 14.6 (CH3).
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10.1002/ejic.201900528
European Journal of Inorganic Chemistry
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Synthesis of BocSerN2H3 (f): 1.00 g (4.56 mmol, 1.00 eq) of boc-
protected L-serine methylester were dissolved in 8 mL methanol and
0.9 mL (13.68 mmol, 3.00 eq) of hydrazine hydrate (80% in methanol)
were added. The solution was stirred overnight, the solvent evaporated
under reduced pressure and a colorless solid was obtained.
119Sn NMR Acetone-d6, 186 MHz,
δ
(ppm): –369. ESI(–)-MS
[C14H25Cl3N3O3Sn]- calc.: 507.9973, found: 507.9980.
Synthesis of RBocLeuSnCl3 (3): 0.050 g (0.154 mmol, 1.00 eq) of 4-
methyl-4-(trichlorostannyl)pentane-2-one and 0.038 g (0.154 mmol,
1.00 eq) of boc-protected leucine hydrazide c were dissolved in 5 mL
dichloromethane. After stirring for 12 hours, the solvent was removed in
vacuo and a colorless powder was obtained.
1H NMR DMSO-d6, 300 MHz, δ (ppm): 8.99 (s, 1H, NH), 6.54 (d,
3J = 8.1 Hz, 1H, NH), 4.85-4.65 (m, 1H, NH), 4.19 (s, 2H, NH2), 3.93 (dd,
2J = 13.5 Hz, 3J = 5.6 Hz, 1H, CH), 3.50 (d, 3J = 4.5 Hz, 2H, CH2), 1.37 (s,
9H, CH3). 13C NMR DMSO-d6, 75 MHz, δ (ppm): 169.6 (Cquart.), 155.0
(Cquart.), 78.1 (Cquart.), 61.9 (CH2), 55.5 (CH), 28.1 (CH3).
1H NMR CDCl3, 300 MHz, δ (ppm): 11.38 (br s, 1H, NH), 5.25 (s, 1H, NH),
4.41 (d, 3J = 6.5 Hz, 1H, CH), 2.83 (s, 2H, CH2), 2.16 (s, 3H, CH3), 1.86-
1.67 (m, 3H, CH, CH2), 1.48 (s, 9H, CH3), 1.46 (d, 4J = 14.71 Hz, 6 H, CH3),
0.97 (d, 3J = 5.9 Hz, 3H, CH3), 0.93 (d, 3J = 5.9 Hz, 3H, CH3). 13C NMR
CDCl3, 75 MHz, δ (ppm): 171.6 (C=O), 157.2 (C=O), 77.4 (Cquart), 52.0
(CH), 51.5 (CH2), 44.1 (Cquart), 39.4 (CH), 28.5 (CH3), 24.8 (CH2), 27.6
(CH3), 27.2 (CH3), 22.9 (CH3), 21.7 (CH3), 20.6 (CH3). 119Sn NMR CD2Cl2,
112 MHz, δ (ppm): –339. ESI(–)-MS [C17H31Cl3N3O3Sn]- calc.: 550.0443,
found: 550.0460.
Synthesis of BocTyrN2H3 (g): 1.00 g (3.39 mmol, 1.00 eq) of boc-
protected L-tyrosine methylester were dissolved in 8 mL methanol and
0.7 mL (10.16 mmol, 3.00 eq) of hydrazine hydrate (80% in methanol)
were added. The solution was stirred overnight, the solvent evaporated
under reduced pressure and a colorless solid was obtained.
1H NMR DMSO-d6, 300 MHz, δ (ppm): 9.12 (s, 1H, OH), 9.04 (s, 1H, NH),
3
3
7.01 (d, J = 8.3 Hz, 2H, Harom.), 6.79 (d, J = 8.4 Hz, 1H, Harom.), 6.63 (d,
3J = 8.3 Hz, 2H, Harom.), 4.18 (s, 2H, NH2), 4.05-3.93 (m, 1H, CH), 2.79-
2.55 (m, 2H, CH2), 1.30 (s, 9H, CH3).13C NMR DMSO-d6, 75 MHz, δ (ppm):
171.0 (Cquart.), 130.0 (Carom.), 128.1 (Carom.,quart.), 114.8 (Carom.), 86.9 (Cquart.),
54.7 (CH), 28.1 (CH3).
Synthesis of RBocPheSnCl3 (4): 0.050 g (0.154 mmol, 1.00 eq) of 4-
methyl-4-(trichlorostannyl)pentane-2-one and 0.043 g (0.154 mmol,
1.00 eq) of boc-protected phenylalanine hydrazide d were dissolved in
5 mL dichloromethane. After stirring for 12 hours, the solvent was removed
in vacuo and a colorless powder was obtained.
Synthesis of BocHisN2H3 (h): 0.50 g (1.85 mmol, 1.00 eq) of boc-
protected L-histidine methylester were dissolved in 5 mL methanol and
0.4 mL (5.57 mmol, 3.00 eq) of hydrazine hydrate (80% in methanol) were
added. The solution was stirred overnight, the solvent evaporated under
reduced pressure and a colorless solid was obtained.
1H NMR CDCl3, 300 MHz, δ (ppm): 7.38-7.21 (m, 5H, Harom), 4.62 (dd,
2J = 14.8 Hz, 3J = 7.8 Hz, 1H, CH), 3.37-3.00 (m, 2H, CH2), 2.84 (d,
3J = 6.4 Hz, 2H, CH2), 2.03 (s, 3H, CH3), 1.51 (d, 2J = 10.4 Hz, 6H, CH2),
1.43 (s, 9H, CH3). 13C NMR CDCl3, 75 MHz, δ (ppm): 170.7 (C=O), 136.1
(Cquart), 129.9 (Carom), 129.5 (Carom), 127.9 (Carom), 54.6 (CH), 51.6 (CH2),
37.0 (CH2), 28.6 (CH3), 27.7 (CH3), 27.3 (CH3), 20.6 (CH3). 119Sn NMR
CD2Cl2, 187 MHz, δ (ppm): –334. ESI(–)-MS [C20H29Cl3N3O3Sn]- calc.:
584.0287, found: 584.0307.
1H NMR DMSO-d6, 300 MHz, δ (ppm): 9.03 (s, 1H, NH), 7.51 (s, 1H NH),
6.81 (d, 3J = 8.1 Hz, 1H, Harom.), 6.74 (s, 1H, Harom.), 4.11 (dd, 2J = 13.7 Hz,
3J = 8.0 Hz, 2H, NH2), 2.76 (qd, 2J = 14.7 Hz, 3J = 7.0 Hz, 2H, CH2), 1.34
(s, 9H, CH3). 13C NMR DMSO-d6, 75 MHz, δ (ppm): 170.9 (Cquart.), 155.1
(Carom.), 134.7 (Carom.), 78.1 (Cquart.), 53.2 (CH), 28.2 (CH3).
Synthesis of RBocMetSnCl3 (5): 0.050 g (0.154 mmol, 1.00 eq) of 4-methyl-
4-(trichlorostannyl)pentane-2-one and 0.041 g (0.154 mmol, 1.00 eq) of
boc-protected methionine hydrazide
e
were dissolved in 5 mL
Synthesis of RBocValSnCl3 (1): 0.050 g (0.154 mmol, 1.00 eq) of 4-methyl-
4-(trichlorostannyl)pentane-2-one and 0.036 g (0.154 mmol, 1.00 eq) of
boc-protected valine hydrazide b were dissolved in 5 mL dichloromethane.
After stirring for 12 hours, a colorless solid precipitates and the solvent was
removed in vacuo to afford a colorless powder.
dichloromethane. After stirring for 12 hours, the solvent was removed in
vacuo and a colorless powder was obtained.
1H NMR CDCl3, 300 MHz, δ (ppm): 11.69 (br s, 1H, NH), 5.70 (s, 1H, CH),
4.60 (dd, 4J = 13.6 Hz, 3J = 7.0 Hz, 1H, CH), 2.85 (s, 1H, CH2), 2.65 (t,
3J = 6.2 Hz, 1H, CH2), 2.29-2.00 (m, 8H, 2xCH3, 1xCH2), 1.54-1.37 (m, 15
H, CH3). 13C NMR CDCl3, 75 MHz, δ (ppm): 171.1 (C=O), 156.9 (C=O),
82.17 (Cquart), 52.3 (CH), 51.5 (CH2), 44.2 (Cquart), 30.62 (Cquart), 30.0 (CH2),
28.5 (CH3), 27.5 (CH3), 26.2 (Cquart), 20.5 (CH3), 15.5 (CH3). 119Sn NMR
CD2Cl2, 112 MHz, δ (ppm): –332. ESI(–)-MS [C16H29Cl3N3O3SnS]- calc.:
568.0006, found: 568.0008.
1H NMR Acetone-d6, 300 MHz, δ (ppm): 6.71 (d, 3J = 8.67 Hz, 1H, NH),
4.17-4.08 (m, 1H, CH), 2.89 (s, 2H, CH2), 2.37 (s, 3H, CH3), 2.21 (td, 2J =
13.6 Hz, 3J = 6.9 Hz, 1H, CH), 1.42 (d, 4J = 4.37 Hz, 6H, CH3), 1.41 (s, 9H,
CH3), 1.06 (t, 3J = 6.1 Hz, 6H, CH3). 13C NMR Acetone-d6, 75 MHz, δ
(ppm): 209.9 (C=O), 173.0 (C=N), 164.7 (C=O), 80.1 (Cquart), 59.5 (CH),
54.9 (CH2), 47.2 (Cquart), 42.4 (CH), 28.6 (CH3), 26.6 (CH3), 19.4 (CH3),
19.3 (CH3). 119Sn-NMR Acetone-d6, 186 MHz, δ (ppm): –373. ESI(–)-MS
[C16H29Cl3N3O3Sn]- calc.: 536.0287, found: 536.0288.
Synthesis of RBocSerSnCl3 (6): 0.050 g (0.154 mmol, 1.00 eq) of 4-methyl-
4-(trichlorostannyl)pentane-2-one and 0.036 g (0.154 mmol, 1.00 eq) of
boc-protected serine hydrazide f were dissolved in 5 mL dichloromethane.
After stirring for 12 hours, the solvent was removed in vacuo and a
colorless powder was obtained.
Synthesis of RBocAlaSnCl3 (2): 0.05 g (0.154 mmol, 1.00 eq) of of 4-
methyl-4-(trichlorostannyl)pentane-2-one and 0.031 g (0.154 mmol,
1.00 eq) of boc-protected alanine hydrazide a were dissolved in 5 mL
dichloromethane. After stirring for several hours, the compound
crystallizes in almost quantitative yield.
1H NMR CDCl3, 300 MHz, δ (ppm): 5.87 (br s, 1H, OH), 4.55 (s, 1H, CH),
4.19-3.79 (m, 2H, CH2), 2.87 (s, 2H, CH2), 2.25 (s, 3H, CH3), 1.45 (s, 15H,
CH3). 13C NMR CDCl3, 75 MHz, δ (ppm): 156.4 (C=O), 81.7 (Cquart), 62.3
(CH2), 53.6 (CH), 51.5 (CH2), 45.3 (Cquart), 28.5 (CH3), 27.4 (CH3), 26.3
(Cquart), 21.0 (CH3). 119Sn NMR CDCl3, 112 MHz, δ (ppm): –340. ESI(–)-
MS [C14H25Cl3N3O4Sn]- calc.: 523.9922, found: 523.9910.
1H NMR Acetone-d6, 500 MHz, δ (ppm): 6.74 (d, 3J = 6.7 Hz, 1H, NH), 4.47
(m, 1H, CH), 3.80 (s, 1H, CH), 2.88 (s, 2H, CH2), 2.34 (s, 3H, CH3), 1.46
(d, 3J = 7.2 Hz, 3H, CH3), 1.43-1.39 (m, 15H, CH3). 13C NMR Acetone-d6,
125 MHz, δ (ppm): 174.3 (C=O), 165.1 (C=N), 156.3 (C=O), 80.1 (Cquart),
52.1 (CH), 49.6 (CH2), 28.5 (CH3), 27.9 (CH3), 19.5 (CH3), 17.4 (CH3).
This article is protected by copyright. All rights reserved.

10.1002/ejic.201900528
European Journal of Inorganic Chemistry
FULL PAPER
Synthesis of RBocTyrSnCl3 (7): 0.050 g (0.154 mmol, 1.00 eq) of 4-methyl-
stirred for 3 days at room temperature. The solvent was removed in vacuo
4-(trichlorostannyl)pentane-2-one and 0.046 g (0.154 mmol, 1.00 eq) of
to afford a colorless solid.
boc-protected tyrosine hydrazide
g
were dissolved in 5 mL
1H NMR CDCl3, 300 MHz, δ (ppm): 5.38 (s, 3H, CH), 4.53-4.04 (m, 3H,
CH), 2.78 (br s, 9H, CH2), 1.92 (s, 9H, CH3), 1.73 (br s, 9H, CH, CH2), 1.43
(s, 45H, CH3), 0.94 (s, 18H, CH3). 13C NMR CDCl3, 75 MHz, δ (ppm): 203.0
(Cquart), 79.8 (Cquart), 53.3 (CH), 51.0 (CH2), 41.2 (Cquart), 28.6 (CH3), 26.8
(CH3), 24.9 (CH, CH2), 23.3 (CH3), 21.7 (CH3). 119Sn NMR CDCl3, 186 MHz,
δ (ppm): –126. ESI(+)-MS [C51H96N9O9S4Sn3]+ calc.: 1464.3286, found:
1464.3291.
dichloromethane. After stirring for 12 hours, a colorless solid precipitates
and the solvent was removed in vacuo to afford a colorless powder.
1H NMR CD2Cl2, 300 MHz, δ (ppm): 7.07 (d, 3J = 7.8 Hz, 2H, Harom), 6.76
(d, 3J = 8.0 Hz, 2H, Harom), 5.50 (s, 1H, CH), 4.56 (d, 3J = 6.5 Hz, 1H, CH),
3.23-2.90 (m, 2H, CH2), 2.82 (s, 2H, CH2), 2.45 (s, 1H, CH), 2.04 (s, 3H,
CH3), 1.53-126 (m, 15H, CH3). 13C NMR CD2Cl2, 75 MHz, δ (ppm): 171.7
(C=N), 157.4 (C=O), 155.8 (Cquart), 131.3 (Carom), 127.5 (Cquart), 116.5
(Carom), 82.9 (Cquart), 55.6 (CH), 52.0 (CH), 44.7 (Cquart), 37.1 (CH2), 28.7
(CH3), 28.0 (CH3), 27.6 (CH3), 26.5 (Cquart), 20.56 (CH3). 119Sn NMR
CD2Cl2, 300 MHz, δ (ppm): –192. ESI(–)-MS [C20H29Cl3N3O4Sn]- calc.:
600.0237, found: 600.0251.
Synthesis of [(RBocPheSn)3S4Cl] (12): 0.185 g (0.309 mmol, 1.00 eq) of
compound 4 were dissolved in 5 mL toluene and 0.03 mL (0.15 mmol,
0.50 eq) of (Me3Si)2S were added at room temperature. The suspension
was stirred for 3 days during which the solid dissolved and a colorless
solution is obtained. The solvent was removed in vacuo and a colorless
solid was obtained.
Synthesis of RBocHisSnCl3 (8): 0.050 g (0.154 mmol, 1.00 eq) of 4-methyl-
4-(trichlorostannyl)pentane-2-one and 0.042 g (0.154 mmol, 1.00 eq) of
1H NMR CDCl3, 300 MHz, δ (ppm): 10.22 (s, 3H, NH), 9.36 (s, 3H, NH),
9.13 (s, 3H, NH), 7.35-71.13 (m, 15H, Harom), 5.18 (s, 3H, CH), 4.53 (s, 3H,
CH), 3.53-2.88 (m, 6H, CH2), 2.88-2.50 (m, 6H, CH2), 1.90 (s, 9H, CH3),
1.31 (s, 45H, CH3). 13C NMR CDCl3, 75 MHz, δ (ppm): 215.2 (Cquart), 168.3
(C=O), 155.5 (C=O), 129.7 (Carom), 128.5 (naphthalene), 128.4 (Carom),
126.8 (Carom), 125.9 (naphthalene), 79.9 (Cquart), 51.1 (CH2), 28.4 (CH3),
26.8 (CH3), 21.7 (CH3). 119Sn NMR CDCl3, 186 MHz, δ (ppm): –66, –94.
ESI(+)-MS [C60H90N9O9S4Sn3]+ calc.: 1566.2820, found: 1566.2838.
boc-protected histidine hydrazide
dichloromethane. After stirring for 12 hours, the solvent was removed in
vacuo and a colorless powder was obtained.
h
were dissolved in 5 mL
1H NMR Acetone-d6, 300 MHz, δ (ppm): 8.91 (s, 1H, Harom), 7.58 (s, 1H,
Harom), 6.12 (s, 1H, NH), 4.46 (s, 1H, CH), 3.29 (s, 2H, CH2), 2.68 (s, 2H,
CH2), 2.15-1.95 (m, 3H, CH3), 1.93-1.79 (m, 1H, CH), 1.40 (s, 15H, CH3).
13C NMR Acetone-d6, 75 MHz, δ (ppm): 210.0 (C=O), 171.1 (C=N), 162.0
(C=O), 155.8 (Cquart), 134.3 (Carom), 130.2 (Cquart,arom), 118.8 (Carom), 79.7
(Cquart), 69.3 (Cquart), 53.9 (CH), 52.2 (CH2), 41.7 (Cquart), 28.8 (CH3), 20.1
(CH), 18.38 (CH3). 119Sn NMR Acetone-d6, 112 MHz, δ (ppm): –385.
ESI(–)-MS [C17H28Cl3N5O3Sn]- calc.: 574.0192, found: 574.0206
Synthesis of [(RBocMetSn)3S4Cl] (13): 0.087 g (0.154 mmol, 1.00 eq) of
compound 5 were dissolved in 4 mL dichloromethane and 0.04 mL
(0.20 mmol, 1.3 eq) (Me3Si)2S were added. The solution was stirred
overnight and the volatile compounds removed in vacuo to afford a
colorless solid.
Synthesis of [(RBocValSn)3S4Cl] (9): 0.165 g (0.309 mmol, 1.00 eq) of
compound 1 were dissolved in 5 mL toluene. 0.06 mL (0.309 mmol,
1.00 eq) of (Me3Si)2S were added at room temperature. After 3 days, the
solvent was removed in vacuo and a colorless solid was obtained.
1H NMR CDCl3, 300 MHz, δ (ppm): 9.26 (br s, 3H, NH), 5.56 (br s, 3H, NH),
4.39 (s, 3H, CH), 2.73 (br s, 6H, CH2), 2.56 (br s, 6H, CH2) 2.05 (s, 9H,
CH3), 1.91 (s, 9H, CH3), 1.41 (s, 45H, CH3). 13C NMR CDCl3, 75 MHz, δ
(ppm): 168.3 (Cquart), 155.5 (Cquart), 79.9 (Cquart), 53.9 (Cquart), 51.1 (CH2),
32.1 (CH2), 30.4 (CH2), 28.5 (CH3), 26.5 (CH3), 21.6 (CH3), 15.6 (CH3).
119Sn NMR CDCl3, 112 MHz, δ (ppm): –66. ESI(+)-MS [C48H90N9O9S7Sn3]+
calc.: 1518.1972, found: 1518.1992.
1H NMR CDCl3, 300 MHz, δ (ppm): 10.11 (br s, 3H, NH), 9.16 (s, 3H, NH),
5.46-5.16 (m, 3H, CH), 4.48-4.08 (m, 3H, CH), 2.90-2.29 (m, 6H, CH2),
1.91 (s, 9H, CH3), 1.52-1.25 (m, 45H, CH3), 1.06-0.83 (m, 18H, CH3). 13
NMR CDCl3, 75 MHz, δ (ppm): 155.9 (C=O), 128.0 (naphthalene), 125.9
(naphthalene), 79.6 (Cquart), 59.1 (CH), 51.2 (CH2), 31.3 (Cquart), 28.8 (CH3),
28.5 (CH3), 26.7 (CH3), 25.9 (CH3), 21.6 (CH3), 19.9 (CH3), 17.8 (CH3).
119Sn NMR CDCl3, 186 MHz,
[C40H90N9O9S4Sn3]+ calc.: 1422.2815, found: 1422.2830.
C
Synthesis of [(RBocSerSn)3S4Cl] (14): 0.081 g (0.154 mmol, 1.00 eq) of
compound 6 were dissolved in 5 mL dichloromethane and 0.04 mL
(0.20 mmol, 1.30 eq) (Me3Si)2S were added. The solution was stirred
overnight and the solvent was removed in vacuo to afford a colorless solid.
δ (ppm): –62, –92. ESI(+)-MS
Synthesis of [(RBocAlaSn)3S4Cl] (10): 0.078 g (0.154 mmol, 1.00 eq) of
compound 2 were dissolved in 4 mL dichloromethane. To this suspension
0.04 mL (0.200 mmol, 1.30 eq) of (Me3S)2S were added. After stirring the
suspension for 14 hours, it turned into a solution and the solvent was
removed in vacuo to afford a colorless powder.
1H NMR CDCl3, 500 MHz, δ (ppm): 9.14 (br s, 3H, NH), 5.66-5.30 (m, 3H,
NH), 4.57-4.16 (m, 3H, CH), 4.04-3.56 (m, 6H, CH2), 2.89-2.48 (m, 6H,
CH2), 1.96-1.80 (m, 9H, CH3), 1.53-1.37 (m, 45H, CH3), 0.33 (s, 27H,
CH3).13C NMR CDCl3, 126 MHz, δ (ppm): 176.0 (Cquart), 166.6 (Cquart),
155.3 (Cquart), 79.8 (Cquart), 55.5 (Cquart), 50.6 (CH2), 28.6 (CH2), 28.4 (CH3),
26.0 (CH3), 21.4 (CH3). 119Sn NMR CDCl3, 186 MHz, δ (ppm): –65, –88.
ESI(+)-MS [C51H102N9O12Si3S4Sn3]+ calc.: 1602.2908, found: 1602.2908.
1H NMR CDCl3, 500 MHz, δ (ppm): 9.00 (br s, 3H, NH), 5.50 (br s, 3H, NH),
4.30 (br s, 3H, CH), 2.88-2.57 (m, 6H, CH2), 1.95-1.84 (m, 9H, CH3), 1.50-
1.36 (m, 15H CH3), 1.35-1.29 (m, 9H, CH3). 13C NMR CDCl3, 125 MHz, δ
(ppm): 170.0 (C=N), 155.4(C=O), 79.8 (Cquart), 51.1 (CH), 50.1 (CH2), 28.5
(CH3), 26.7 (CH3), 26.0 (CH3), 21.6 (CH3), 18.5 (CH3). 119Sn NMR CDCl3,
186 MHz, δ (ppm): –67, –95. ESI(+)-MS [C42H78N9O9S4Sn3]+ calc.:
1336.1870, found: 1336.1902.
Synthesis of [(RBocTyrSn)3S4Cl] (15): 0.092 g (0.154 mmol, 1.00 eq) of
compound 7 were dissolved in 5 mL dichloromethane and 0.04 mL
(0.20 mmol, 1.30 eq) (Me3Si)2S were added. The solution was stirred
overnight and the solvent was removed in vacuo to afford a colorless solid.
Synthesis of [(RBocLeuSn)3S4Cl] (11): 0.170 g (0.309 mmol, 1.00 eq) of
compound 3 were dissolved in 5 mL toluene. After adding 0.03 mL
(0.15 mmol, 0.50 eq) (Me3Si)2S the solution remained colorless and was
1H NMR CD2Cl2, 300 MHz, δ (ppm): 7.22-7.03 (m, 6 H, Harom), 6.75 (s, 6H,
Harom), 4.48 (s, 3H, CH), 3.38-2.83 (m, 6H, CH2), 2.83-2.53 (m, 6H, CH2),
1.87 (s, 9H, CH3), 1.32 (s, 45 H, CH3), 0.23 (s, 27H, CH3). 13C NMR CD2Cl2,
75 MHz, δ (ppm): 155.8 (Cquart), 154.6 (Cquart), 131.1 (CH2), 120.4 (CH2),
This article is protected by copyright. All rights reserved.

10.1002/ejic.201900528
European Journal of Inorganic Chemistry
FULL PAPER
80.1 (Cquart), 56.0 (Cquart), 51.3 (CH2), 28.6 (CH3), 26.8 (CH3), 21.9 (CH3).
δ (ppm): –68, –92. ESI(+)-MS
[C69H114N9O12Si3S4Sn3]+ calc.: 1830.3852, found: 1830.3852.
155.5 (C=O), 136.8 (Cquart), 129.6 (Carom), 128.5 (Carom), 126.8 (Carom), 80.0
(Cquart), 55.3 (CH), 51.0 (CH2), 37.9 (CH2), 31.9 (CH3), 29.4 (CH3), 28.4
(CH3), 26.3 (CH3), 21.7 (CH3). 119Sn NMR CD2Cl2, 186 MHz, δ (ppm):
–115. ESI(+)-MS [C60H90N9O9S4Sn3]+ calc.: 1566.2820, found: 1566.2848.
119Sn NMR CD2Cl2, 186 MHz,
Synthesis of [(RBocHisSn)3S4Cl] (16): 0.088 g (0.154 mmol, 1.00 eq) of
compound 8 were dissolved in 4 mL dichloromethane and 0.04 mL
(0.20 mmol, 1.30 eq) (Me3Si)2S were added. The solution was stirred
overnight and the volatile compounds removed in vacuo to afford a
colorless solid.
Acknowledgments
We thank Eike Dornsiepen and the X-Ray Department of the Philipps-
Universität Marburg for the crystal structure measurement. This work
was financially supported by LOEWE “SynChemBio”.
1H NMR CDCl3, 300 MHz, δ (ppm): 6.95 (br s, 3H, Harom), 6.43-5.87 (m,
3H, Harom), 4.55 (br s, 3H, CH), 3.32-2.55 (m, 12H, CH2), 2.10-1.72 (m, 9H,
CH3), 1.61-1.15 (m, 45H, CH3). 13C NMR CDCl3, 75 MHz, δ (ppm): 155.6
(C=O), 80.0 (Cquart), 51.0 (CH2), 28.5 (CH3), 23.5 (CH3), 21.6(CH3). Due to
bad solubility of the cluster as well as dynamic effects, we were not able
to get a 13C NMR spectrum that shows all signals. 119Sn NMR CD2Cl2, 186
MHz, δ (ppm): –69, –86. ESI(+)-MS [C51H84N15O9S4Sn3]+ calc.: 1536.2531,
found: 1536.2555.
Keywords: bio-organotin halides • bio-organotin chalcogenide
clusters • NMR spectroscopy • ESI mass spectrometry • X-ray
diffraction
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Synthesis of [(RBocValSn)4S6] (17): 0.992 g (1.80 mmol, 1.00 eq) of
compound 1 were dissolved in 15 mL acetone. At –10 °C 0.450 g
(1.80 mmol, 1.00 eq) of Na2S•9H2O in an acetone water mixture (3 mL
each) was added. The colorless solution was stirred for 10 minutes. The
solvent was removed then in vacuo, and the solid was dried overnight. The
colorless solid was re-dissolved in dichloromethane and filtered. After
removing the solvent in vacuo a colorless solid was obtained.
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1H NMR CDCl3, 300 MHz, δ (ppm): 9.02 (br s, 2H, NH), 4.22 (br s, 4H, CH),
2.95-2.68 (m, 8H, CH2), 2.36-1.81 (m, 12H, CH3), 1.41 (s, 60H, CH3), 1.07-
0.84 (m, 24H, CH3). 13C NMR CDCl3, 75 MHz, δ (ppm): 210.9 (C=O), 168.6
(C=N), 156.3 (C=O), 80.3 (Cquart), 59.0 (CH), 51.0 (CH2), 31.2 (CH), 28.6
(CH3), 28.4 (CH3), 26.2 (CH3), 25.7 (CH3), 21.9 (CH3), 19.9 (CH3), 18.2
(CH3), 17.8 (CH3). 119Sn NMR CDCl3, 186 MHz, δ (ppm): –62, –116.
ESI(+)-MS [C48H90N9O9S4Sn3]+ calc.: 1420.2809, found: 1422.2873.
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compound 3 were dissolved in 5 mL acetone. The solution was cooled to
–10 °C. A solution of 0.450 mg (1.80 mmol, 1.00 eq) Na2S•9H2O in a
mixture of acetone and degassed water (3 mL each), was added. After
several minutes, a colorless solid precipitated and the solvent was
removed in vacuo. After drying overnight, the solid was re-dissolved in
dichloromethane and filtered. The solvent was removed in vacuo again to
afford a colorless solid.
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210.9 (C=O), 169.5 (C=N), 155.7 (C=O), 79.8 (Cquart), 53.3 (CH), 50.9
(CH2), 41.3 (Cquart), 28.5 (CH3), 26.2 (CH3), 24.8 (CH), 23.2 (CH3), 21.7
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solution of 0.45 g (1.80 mmol, 1.00 eq) Na2S•9H2O in 3 mL acetone and
3 mL degassed water was added. A suspension was formed and the
solvent was removed after 10 minutes. The residue was dried overnight
and then re-dissolved in dichloromethane and filtered. After removing the
solvent in vacuo a colorless solid was obtained.
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4H, CH), 3.45-2.90 (m, 8H, CH2), 2.07-1.78 (m, 12H, CH3), 1.54-1.18 (m,
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10.1002/ejic.201900528
European Journal of Inorganic Chemistry
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10.1002/ejic.201900528
European Journal of Inorganic Chemistry
FULL PAPER
Entry for the Table of Contents
FULL PAPER
We present a new versatile route
to amino acid-functionalized tin
sulfide clusters. After condensation
of boc-protected amino acid
hydrazides with a keto
functionalized organotin trichloride,
reaction with either (Me3Si)2S or
Na2S leads to the corresponding
defect-heterocubane-type or
“doppeldecker”-type clusters. The
compounds were characterized by
means of single-crystal X-ray
diffraction, 1H,13C and 119Sn NMR
spectroscopy, as well as by mass
spectrometry.
Bio-organotin chalcogenides
Annikka Engel, Stefanie Dehnen*
Page No. – Page No.
Amino Acid-Functionalized
Organotin Trichlorides and Their
Tin Sulfide Clusters
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