Aminostannanes and aminostannylenes containing a C,N-chelated ligand

Article abstract of DOI:10.1016/j.jorganchem.2010.08.013

Aminotin(II and IV) compounds {[(2,6-i-Pr-C₆H ₃)(H)N]-μ-(Sn)-Cl}₂, {2-[(CH₃) ₂NCH₂]C₆H₄}₂Sn[N(H)(2,6- i-Pr-C₆H₃)]₂ and {2-[(CH₃) ₂NCH₂]C₆H₄}Sn[N(2,6-i-Pr-C ₆H₃)(SiMe₃)] were prepared by lithium halide elimination from tin halides and corresponding lithium complexes. [(2,6-i-Pr-C₆H₃)(H)N]Li (1) reacts with one half of molar equivalent of SnCl₂ to give {[(2,6-i-Pr-C₆H ₃)(H)N]-μ-(Sn)-Cl}₂. The same lithium amide (1) gave with R₃SnCl corresponding aminostannanes. Further reactions of these compounds with n-butyllithium gave the starting 1 and tetraorganostannanes. {2-[(CH₃)₂NCH₂]C₆H₄} ₂SnBr₂ reacts with two equivalents of 1 to {2-[(CH ₃)₂NCH₂]C₆H₄} ₂Sn[N(H)(2,6-i-Pr-C₆H₃)]₂. The dimeric heteroleptic stannylene {[(2,6-i-Pr-C₆H₃) (SiMe₃)N](μ₂-Cl)Sn}₂ reacts with 2-[(CH ₃)₂NCH₂]C₆H₄Li to the monomeric {2-[(CH₃)₂NCH₂]C₆H ₄}Sn[N(2,6-i-Pr-C₆H₃)(SiMe₃)]. The structure in the solid state and in solution and reactivity of products is also discussed. The unique decatin cluster has been isolated by hydrolysis of {[(2,6-i-Pr-C₆H₃)(H)N]-μ-(Sn)-Cl}₂. The structure of some compounds was also evaluated by theoretical DFT methods.

Full text of DOI:10.1016/j.jorganchem.2010.08.013

Journal of Organometallic Chemistry 695 (2010) 2651e2657
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Aminostannanes and aminostannylenes containing a C,N-chelated ligand
a
a
a
b
,
c
a,
ꢀ
*
ꢀ
ꢀ
ꢀ
ꢀ ꢁꢀ ꢀ
Zdenka Padelková , Ales Havlík , Petr Svec , Mikhail S. Nechaev , Ales Ruzicka
a
ꢀ
Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, nám. Cs. legií 565, CZ-532 10, Pardubice, Czech Republic
b Department of Chemistry, Moscow State University, Leninskie gory, 1 (3), GSP-2, Moscow 119992, Russian Federation
c A.V. Topchiev Institute of Petrochemical Synthesis, RAS, Leninsky Prosp., 29, Moscow 119991, Russian Federation
a r t i c l e i n f o
a b s t r a c t
Article history:
Aminotin(II and IV) compounds {[(2,6-i-Pr-C6H3)(H)N]-m-(Sn)-Cl}2, {2-[(CH3)2NCH2]C6H4}2Sn[N(H)
(2,6-i-Pr-C6H3)]2 and {2-[(CH3)2NCH2]C6H4}Sn[N(2,6-i-Pr-C6H3)(SiMe3)] were prepared by lithium
halide elimination from tin halides and corresponding lithium complexes. [(2,6-i-Pr-C6H3)(H)N]Li
Received 18 March 2010
Received in revised form
9 August 2010
Accepted 13 August 2010
Available online 20 August 2010
(1) reacts with one half of molar equivalent of SnCl2 to give {[(2,6-i-Pr-C6H3)(H)N]-m-(Sn)-Cl}2. The
same lithium amide (1) gave with R3SnCl corresponding aminostannanes. Further reactions of these
compounds with n-butyllithium gave the starting 1 and tetraorganostannanes. {2-[(CH3)2NCH2]
C6H4}2SnBr2 reacts with two equivalents of 1 to {2-[(CH3)2NCH2]C6H4}2Sn[N(H)(2,6-i-Pr-C6H3)]2. The
dimeric heteroleptic stannylene {[(2,6-i-Pr-C6H3)(SiMe3)N](m2-Cl)Sn}2 reacts with 2-[(CH3)2NCH2]
C6H4Li to the monomeric {2-[(CH3)2NCH2]C6H4}Sn[N(2,6-i-Pr-C6H3)(SiMe3)]. The structure in the
solid state and in solution and reactivity of products is also discussed. The unique decatin cluster has
ꢀ
Dedicated to Dr. Bohumil Stíbr on the
occasion of his 70th birthday in recognition
of his outstanding contributions to the area
of boron and organometallic chemistry.
been isolated by hydrolysis of {[(2,6-i-Pr-C6H3)(H)N]-
was also evaluated by theoretical DFT methods.
m
-(Sn)-Cl}2. The structure of some compounds
Keywords:
Tin(II and IV) compounds
Bulky amino group
C,N-Chelating ligand
DFT calculations
Ó 2010 Elsevier B.V. All rights reserved.
ꢁ
1. Introduction
or XRD techniques oscillate around the value of 2.05 A. The structure
and reactivity of some stannaimines of R2Sn ¼ NR’ type have also
been investigated previously [6]. The 15N NMR parameters of above
mentioned compounds were reviewed by Wrackmeyer [7].
The group of aminostannanes [1] is well established and
compounds with covalent Sn-N bonds, particularly compounds of
Sn-NR2 type playan interesting role in structural chemistryand they
provide a route to various new types of compounds, mainly due to
the high reactivity of SneN bond. Especially the reactivity of these
compounds, where NR2 group can act as a mild nucleophile, in
substitution or addition reactions is very important. Also the prod-
ucts of reactions with protic acids, heterocumulenes or other singly-
or doubly bonded electrophiles [2] constitute interesting groups of
molecules. The structure of aminostannanes strongly depends on
steric hindrance and electronic demand of tin and nitrogen
substituents which is illustrated in the next paragraph. The
(Me3Sn)3N [3] and ArN(SnMe3)2 [4] (Ar ¼ 2,6-(diisopropyl)phenyl e
Fig. 1) are monomeric, and (t-Bu2SnN-t-Bu)2 is dimeric [5] with
planar four membered ring, all of them having planar geometry at
nitrogen atoms. On the other hand, in (t-Bu2SnNH)3, the ring is again
planar but the nitrogen atoms display a distorted pyramidal
configuration. The SneN interatomic distances determined by GED
The Sn-N donor interaction is frequently involved as a driving force
to electronic and kinetic stabilization of compounds where the tin
atom is present in lower [8] oxidation states. These thermally robust
complexes in which amino substituents, whether bulky or not, are
involved, are studied as a higher congeners of N-heterocyclic carbenes
which are useful in transition metal coordination and catalysis [9].
The unusual 1,3-diaza-2,4-distannylcyklobutanide with an
aromaticity bonding character within the ring has been prepared by
reaction of {[(Me3Si)2N]2Sn-m-Cl}2 with AgOCN [10]. Similar
compounds with bridging chlorine atoms [11] reveal different reac-
tivity, and {[(2,6-i-Pr-C6H3)(SiMe3)N](m2-Cl)Sn}2 [12] is the only
compound of this type which can be reduced to the endo Sn15 cluster.
The phosphorus and arsenic analogues of amino-bridged
compounds are But2E15SneCl (E15 ¼ P or As) as the centrosym-
metric dimers with bridging E15But2 groups with unusually short
interatomic E15eSn distances [13].
In this paper we present the joint effect of tin atom stabilization
by both bulky amino substituents and C,N-chelating ligand, used
for similar purposes recently [14].
* Corresponding author. Tel.: þ42 04 6603 7151; fax: þ42 04 6603 7068.
ꢁꢀ ꢀ
E-mail address: ales.ruzicka@upce.cz (A. Ruzicka).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.08.013

ꢀ
2652
Z. Padelková et al. / Journal of Organometallic Chemistry 695 (2010) 2651e2657
THF
R3SnCl + ArN(H)Li
R3SnN(H)Ar
R = nBu(2), Ph(3)
- LiCl
(1)
THF
- LiCl
THF
R3SnN(H)Ar + nBuLi
R3Sn-nBu + ArN(H)Li
(LCN)2SnBr2 + 2 ArN(H)Li
(LCN)2Sn[N(H)Ar]2
- LiBr
(5)
(4)
Cl
Sn
THF
2 SnCl2 + 2 ArN(H)Li
Cl
Ar(H)N
Cl
N(H)Ar
- LiCl
Sn
(6)
THF
+ 2 LCNLi
2 LCNSnN[(SiMe3)(Ar)]
[Ar(SiMe3)]NSn
SnN[Ar(SiMe )]
3
- LiCl
(7)
(8)
Cl
6´
6´
5´
(CH3)2N
2´
2
Ar
3
1´
3´
4´
1
LCN
4
6´
2´
6
5
5´
3´
6´
Fig. 1. Reactivity and numbering (NMR) of compounds studied.
ꢁ
2. Results and discussion
(Sn1eN41 4.7880(18) A). The tin coordination geometry is that of
deformed trigonal bipyramid with the atom N31 of chelating
ligand and one of the arylamino substituents (distance Sn1eN1
All the compounds mentioned in the text are sensitive to air and
moisture. The reactions of [(2,6-i-Pr-C6H3)(H)N]Li (1) with Ph3SnCl
and nBu3SnCl (Fig. 1) yielded corresponding aminostannanes of
R3Sn[N(H)-(2,6-i-Pr-C6H3)] type (R ¼ nBu (2), Ph (3) as yellowish
oils in high yields. The trialkytin(IV) derivative 2 as well as the
triaryltin(IV) compound 3 reveal one set of rather broad signals in
1H NMR spectra with the approximate half-height line-width about
300 Hz. Also the signals found in 119Sn NMR spectra are rather
broad at room temperature e with the approximate half-height
line-width about 650 Hz. Values of the chemical shifts of 2 and 3 are
in line with previously published shifts for related aminostannanes
[15] Compounds 2 and 3 react with one equivalent of 1-butyl-
lithium or with lithium diisopropylamide to give the products of
transmetallation e [(2,6-i-Pr-C6H3)(H)N]Li [16] and tetraorganotin
(IV) compounds at ꢀ78 ꢁC.
ꢁ
is 2.0971(15) A) in axial positions. The ipso carbon atoms and the
remaining nitrogen atom of the aniline substituents are located
in equatorial positions. The distance of the plane defined by
Reaction of one to 2 M equivalents of [(2,6-i-Pr-C6H3)(H)N]Li (1)
with 1 M equivalent of doubly C,N-chelated diorganotin(IV)
dibromide (4) gives compound {2-[(CH3)2NCH2]C6H4}2Sn[N(H)
(2,6-i-Pr-C6H3)]2 (5) essentially quantitatively. Compound
5
displays a single relatively sharp signal (half-height line-width
about 80 Hz) with the chemical shift value ꢀ161.1 ppm in 119Sn
NMR spectrum. This value is within the range for diorganotin(IV)
compounds carrying C,N-chelating ligands [17] In the 1H NMR
spectrum at room temperature, both anilinate moieties are
isochronous but both dimethylaminomethyl groups resonate at the
same frequency. The same non-equivalence for N-aryl groups is
also visible from 13C and 15N NMR spectra parameters where two
distinct sets of signals for anilinate moieties were found (Fig. 2).
On the other hand, the molecular structure determination of
5 in the solid state shows two different dimethylamino groups
where the first one is medium-weakly coordinated to the tin
Fig. 2. The molecular structure (ORTEP 50% probability level) of 5, hydrogen atoms are
ꢁ
ꢁ
omitted for clarity. Selected interatomic distances [A] and angles [ ]: Sn1eN1 2.0971
(15), Sn1eN2 2.0680(16), Sn1eN31 2.6987(16), Sn1eN41 4.7880(18), Sn1eC31 2.1427
(19), Sn1eC41 2.1511(19), N1eSn1eN2 97.66(6), N1eSn1eN31167.86(6), N1eSn1eC31
102.57(7), N2eSn1eC31 117.60(7), N1eSn1eC41 105.05(7), N2eSn1eC41 122.47(7),
C31eSn1eC41 107.94(7).
ꢁ
atom (Sn1eN31 distance is 2.6987(16) A) and the second
nitrogen atom is out of the tin primary coordination sphere

ꢀ
Z. Padelková et al. / Journal of Organometallic Chemistry 695 (2010) 2651e2657
2653
ꢁ
these three atoms from the tin atom is 0.427(2) A. There is
significant difference between SneN (aryleN1 and N2) distances
caused probably by a trans- effect of dimethylamino group anꢁd
terminal Sn(IV)eN bonds to the same ligand are present. The SneN
distances are almost equal in the first one polymorph but rather
distinct in the centrosymmetric polymorph of 6. The chlorine
atoms lie at the same side bellow the Sn2N2 ring with SneCl bond
being almost perpendicular to the ring. The SneCl bond lengths are
similar to values found in Cambridge Crystallographic Database for
typical SneCl terminal bonds. The small difference in SneCl
distances between both polymorphs is probably caused by
a slightly larger repulsion in the centrosymmetric polymorph.
Surprisingly, the NeH bonds are oriented toward the same side of
the Sn2N2 ring as the two SneCl bonds. The structure of 6 can be
compared to the compounds described previously in the literature.
There is a number of compounds with tin(II) atoms bridged by
amino ligands, some of them are oligomeric, mainly tetranuclear
with a heterocubane structure [18], others having trinuclear six-
membered ring arrangement [19], and the remaining ones contain
two tin atoms as described mainly by Veith, Lappert or Khrustalev
[20e24]. These compounds are chloro aminogermylene and ami-
nostannylene of formulae R2NeE14eCl (E14 ¼ Ge or Sn) which form
dimers through the singly of doubly bridging amino ligands, with
terminal chloro ligands in mutual trans configuration. When
compared to 6, the tin compound of Khrustalev [24],
(Me2NeSneCl)2, has an almost planar Sn2N2 ring and a trans
configuration of the SneCl bonds. The same orientation of SneCl
bonds in 5 could be explained by the discrepancy in steric bulk of
the nitrogen substituents. The remaining interatomic distances and
angles are similar.
ꢁꢁ
a weak H-bridge N2eH2/N31 being 2.993(2) A and 89.3 .
Heating of colorless crystals of 5 under vacuo to 160 ꢁC, led to the
formation of a dark red insoluble slurry and the elimination of
the parent amine (2,6-i-Pr-C6H3NH2 e proven by GC/MS).
The reaction of 1 M equivalent of [(2,6-i-Pr-C6H3)(H)N]Li with
SnCl2 gave compound 6 as a sole product. The white crystalline
compound 6 is soluble in organic solvents and reveals instability
towards air and moisture. The 1H NMR spectrum of 6 reveals two
broad signals for CH moieties of isopropyl groups at 3.62 and
2.75 ppm, respectively, indicating their non-equivalency in solution
at room temperature. The remaining signals are broad and only the
signal at 5.82, attributed to NH group, shows satellites due to
the coupling with tin 22.3 Hz. This signal is significantly shifted to
the higher value in comparison to appropriate signals found in 1H
NMR spectrum of 6 (3.34 and 3.98 ppm). In the 119Sn NMR spec-
trum, one broad signal at ꢀ29.5 ppm is found at 295K but all the
attempts to find a decoalescence temperature failed. The 119Sn NMR
chemical shift of 6 shifts to low frequency upon temperature
decrease, which suggests a possible fast dynamic equilibrium
between dimer 6 and its monomeric unit, decreasing the temper-
ature favouring dimer formation. Alternatively, this can reflect the
N->Sn interaction becoming increasingly strong when the
temperature is lowered, which leads to increased 119Sn nucleus
shielding. The chemical shift value is comparable to the value found
for 7 [12] where the tin atom is also three coordinated and ligated
by the same ligand.
Tin amido chlorides CleSneNRR0 can adopt different types of
structures in solid state (Scheme 1): chloro-bridged dimer B
(R ¼ R0 ¼ SiMe3, [11]) and trimer C (R ¼ SiMe3, R0 ¼ Mes, [19]),
amido bridged dimers D (R ¼ R0 ¼ Me, [24]) and E (R ¼ H, R0 ¼ Dipp,
5). Monomeric structures of the type A are not known to date. This
seems natural since steric protection of tin by bulky substituents of
amido group can block the central atom only from one side while
the other side is accesible for coordination by at least chlorine atom.
We performed DFT study of structures of CleSneNRR0 type.
Relative energies of monomers, dimers and trimers in gas phase
were calculated at PBE/TZ2P level (Table 1). All compounds under
study can adopt any type of structures BeE, although relative
energies in respect to monomers A lie in a wide range. Notably, the
lowest calculated energies correspond to structures found
experimentally.
The structure of 6 has been determined by X-ray diffraction. Two
different polymorphs of 6 and 60 were identified. Both polymorphs
crystallize in monoclinic crystal system (see Experimental part) and
the main differences are associated with slight changes in bond
distances and interatomic angles. In the centrosymmetric poly-
morph, the SneCl bonds are almost parallel, in the second one, the
angle between the planes defined by mentioned bonds and the
centroid of the ring is 8.2ꢁ. The tin atoms are bridged by nitrogen
atoms forming thus a four membered diazadistanna heterocycle
(Fig. 3). The SneN bonds in 6 and 60 are elongated by approximately
ꢁꢁ
0.2 A in comparison to appropriate distances found in 5, where the
Compounds bearing the most bulky substituents at nitrogen
adopt structures B and C, respectively. These are the only structures
for which relative energies are negative. The least substituted
adopts amido bridged structure D (ꢀ7.3 kcal/mol) with trans-
arrangement of chlorine atoms. We suppose that chlorine atoms
occupy mutual trans-positions to avoid steric congestion, 6-E with
R'
N
R
N
Cl
R
R
R
R
Sn Sn R'
Cl
Cl Sn N
R'
A
N Sn Sn N
Cl
Cl
Cl
Sn
N
R'
R'
R'
R
B
C
R R'
R R'
N
N
Fig. 3. The molecular structure (ORTEP 50% probability level) of 60. Selected inter-
Cl Sn Sn Cl Cl Sn Sn Cl
ꢁ
ꢁ
N
R R'
N
R R'
atomic distances [A] and angles [ ]; the appropriate parameters for the centrosym-
metric polymorph (5) are given in parentheses: Sn1eN1 2.272(3) (2.243(7)), Sn1eN2
2.267(3) (2.308(6)), Sn2eN1 2.272(3), Sn2eN2 2.265(3), Sn1eCl1 2.4401(11) (2.481
(2)), Sn2eCl2 2.4356(10), N1eSn1eN2 76.29(11) (78.5(2)), N1eSn1eCl1 86.94(8)
(84.42(15)), N2eSn1eCl1 89.84(8) (89.26(16)), N1eSn2eN2 76.33(11), N1eSn2eCl2
87.28(8), N2eSn2eCl2 89.17(8), Sn1eN2eSn2 100.49(12).
D
E
Scheme 1.

ꢀ
Z. Padelková et al. / Journal of Organometallic Chemistry 695 (2010) 2651e2657
2654
Table 1
Calculated relative Gibbs free energies of mono and oligomers of CleSneNRR0 AeE
(6G in kcal/mol in respect to one subunit, structures found experimentally in bold).
Type
R ¼ SiMe3
R ¼ SiMe3
R ¼ SiMe3
R ¼ Mes
R ¼ Me
R0 ¼ Me
R ¼ H
R0 ¼ Dipp
A
B
C
D
E
0.0
ꢀ0.4
0.8
6.0
6.7
0.0
0.4
ꢀ0.5
13.7
15.3
0.0
0.5
1.9
0.0
ꢀ0.5
1.6
ꢀ7.3
ꢀ3.2
ꢀ5.8
ꢀ7.5
cis-arrangement of chlorides has a higher in energy (ꢀ5.8 kcal/
mol). In 6 each nitrogen atom bears one bulky 2,6-diisopropyl-
phenyl (Dipp) group, even though nitrogen to tin coordination can
still occur in 6-E (ꢀ7.5 kcal/mol). In this case, cis-arrangement of
chlorides decreases steric repulsion from Dipp groups, vide supra.
Relative energy of 6-D is 4.3 kcal/mol higher than of 6-E.
Notably, in the absence of steric congestion about nitrogen atom
bridging by amido groups favours over bridging by chlorides.
Otherwise, only chloro-bridged dimers would be formed inde-
pendently from steric congestion of amido groups. Heavy steric
loading of amido groups only leads to formation of weakly bound
chloro-dimers. Formation of amido-dimers gains more than 7 kcal/
mol in free energy, while the bridging by chlorides gains less than
1 kcal/mol.
Fig. 4. The molecular structure (ORTEP 50% probability level) of 6a, some hydrogen
atoms are omitted for clarity. Selected interatomic distances [A] and angles [ꢁ]:
ꢁ
Sn2eO1b 2.051(4), Sn2eO1a 2.052(4), Sn2eO1 2.052(4), Sn2eO2b 2.068(4), Sn2eO2a
2.068(4), Sn2eO2 2.069(4), Sn2eSn1b 3.2301(6), Sn2eSn1a 3.2310(6), Sn2eSn1 3.2318
(6), Sn3eO3 2.0822(8), Sn3eO1 2.098(4), Sn3eCl1 2.822(2), Sn4eO2 2.090(4), Sn4eCl2
2.455(2), Sn1eO2 2.096(4), Sn1eO1 2.106(4), Sn1eN1 2.261(5), O3eSn3b 2.0808(8),
O3eSn3a 2.0822(8), N1eSn4 2.253(5), Cl1aeSn3 2.792(2), O1beSn2eO1a 99.68(15),
O1eSn2eO1b 99.68(15), O1eSn2eO1a 99.64(15), O1beSn2eO2b 79.06(16),
O1aeSn2eO2b 165.39(16), O1eSn2eO2b 94.91(17), O1beSn2eO2a 94.94(17),
O1aeSn2eO2a 79.02(16), O1aeSn2eO2 165.32(16), O2beSn2eO2a 86.56(17),
O1eSn2eO2b 165.39(16), O1eSn2eO2a 94.88(17), O1eSn2eO2 79.00(16),
O2eSn2eO2b 86.53(17), O2eSn2eO2a 86.53(17), Sn1beSn2eSn1a 119.220(5),
O3eSn3eO1 87.6(2), O3eSn3eCl1a 80.85(5), O1eSn3eCl1a 82.38(13), O1eSn3eCl1
89.19(13), Cl1eSn3eCl1a 159.42(6), O2eSn4eN1a 89.28(17), Sn2eO1eSn3 125.1(2),
Sn2eO1eSn1 102.01(18), Sn3eO1eSn1 124.3(2), Sn3beO3eSn3a 119.29(6).
Many reactions of compound 6 were also investigated including
attempts to reduce 6 by different reagents as for example potas-
sium, potassium graphite, lithium naphthenide etc. but only
inseparable mixtures of unidentified products and reactants were
obtained.
atoms containing three terminal chlorine atoms and one bridging
amino ligand connecting this level with upper tin atoms.
The interatomic distances found in 6a are comparable to usual
distances found for similar bonds in the Cambridge Crystallo-
graphic Database. The SneCl distances (Table 2) are also
comparable to those found in tetranuclear compound published
by us very recently, where also terminal and bridging SneCl
bonds are present [25].
Last, the reaction of the heteroleptic aminostannylene 7, used
also by one of us for preparation of Sn15 endo cluster [12], with the
lithium salt of C,N-chelating ligand was investigated (Scheme 1).
This reaction gave compound 8 (Fig. 5) as yellowish crystals in
essentially quantitative yield.
When the compound 6 was left in a freezer and the stopcock
was not greased enough, the unique oxo-decatin cluster 6a was
isolated by pure luck as a single crystalline insoluble material.
The attempts to prepare 6a were made many times but we were
not successful to reproduce the primary result anymore. The
compound 6a (Scheme 2 and Fig. 4) crystallizes in trigonal
system and consists of ten tin, six chlorine, seven oxygen atoms
and three e [N(H)(2,6-i-Pr-C6H3)] ligands. Four different types of
tin atoms are present in the structure of 6a: i) three atoms on the
top of the cluster connected by OH group in the middle of the
triangle, three chlorine and three oxygen atoms to the lower
level, ii) the middle tin atom is associated to the remaining nine
tin atoms by oxygen bridges, iii) the middle level is made up by
three tin atoms each of which is connected by two oxygen atoms
to the lower as well as upper levels and one bridging amino
ligand to the lower level, iv) the lowest level consists of three tin
One set of relatively narrow signals was found in 1H NMR
spectrum of 8. In 119Sn NMR spectrum, there is only one sharp
signal at 326.9 ppm which is between the values for homoleptic
stannylenes {2-[(CH3)2NCH2]C6H4}2Sn (144.5 ppm) [14] and Sn[N
(SiMe3)(2,6-i-Pr-C6H3)]2 (439.6 ppm) [26] which are formed if 8 is
heated or is left for a couple of days in toluene solution. 8 can be
Cl
Sn
H
O
Cl
Sn
O
Table 2
Sn
ꢁ
Selected bond lengths [A] for compounds 5e8.
Cl
O
Compound
Sn1eN1
Sn1eN2
Sn1eCl1
Sn
O
5
6
2.0971(15)
2.272(3)a
2.272(3)
2.243(7)
2.261(5)
2.133(3)
2.0680(16)
2.267(3)
2.265(3)
2.308(6)
2.253(5)b
2.368(3)
e
Sn
O
2.4401(11)
2.4356(10)
O
Sn
Sn
O
60
6a
8
2.481(2)
2.822(2)c, 2.455(2)d, 2.792(2)e
Sn
Cl
Sn
Cl
N
e
N
Sn
Cl
H
H
a
Ar
N
Two independent molecules.
N1eSn4.
Sn3eCl1.
Sn4eCl2.
Cl1aeSn3.
b
c
Ar
H
Ar
d
e
Scheme 2.

ꢀ
Z. Padelková et al. / Journal of Organometallic Chemistry 695 (2010) 2651e2657
2655
4. Preparation of compounds studied
4.1. (n-Bu)3SnN(H)Ar (2)
(n-Bu)3SnCl (1.814 g, 5.57 mmol) was dissolved in 30 mL of
benzene and suspension of ArN(H)Li (1.021 g, 5.57 mmol) in 30 mL
of benzene was added in 15 min. The reaction mixture was stirred
at room temperature for 12 h. Afterwards the reaction mixture was
filtered and the filtrate was evaporated in vacuo to dryness giving
a yellow oily product. Yield 2.208 g (85%). 1H NMR (C6D6, 295 K,
ppm): 7.12 (d, 2H, H(30)), 6.95 (t, 1H, H(40)), 3.32 (m, 2H, H(50)), 2.76
(s, 1H, NH), 1.58 (m, 6H, H(10)), 1.35 (m, 6H, H(20)), 1.27 (d, 12H, H
(60)), 1.12 (m, 6H, H(30)), 0.97 (t, 9H, H(40)). 119Sn NMR (C6D6, 295 K,
ppm): 40.1. Elemental analysis (%): found: C, 62.0; H, 9.9; N, 2.8;
calcd for C24H45NSn (466.32): C, 61.82; H, 9.73; N, 3.00.
4.2. Ph3SnN(H)Ar (3)
Ph3SnCl (1.673 g, 4.34 mmol) was dissolved in 30 mL of benzene
and a suspension of ArN(H)Li (0.795 g, 4.34 mmol) in 30 mL of
benzene was added in 15 min. The reaction mixture was stirred at
room temperature for 12 h. Afterwards the reaction mixture was
filtered and the filtrate was evaporated in vacuo to dryness giving
yellow oily product. Yield 2.033 g (89%). 1H NMR (C6D6, 295 K,
ppm): 7.60 (d, 6H, H(20)), 7.35 (m, 12H, H(30), H(40)), 7.12 (d, 2H, H
(30)), 6.98 (t, 1H, H(40)), 3.32 (m, 2H, H(50)), 2.72 (s, 1H, NH), 1.12 (d,
12H, H(60)). 119Sn NMR (C6D6, 295 K, ppm): ꢀ111.5. Elemental
analysis (%): found: C, 68.7; H, 6.2; N, 2.8; calcd for C30H33NSn
(526.29): C, 68.47; H, 6.32; N, 2.66.
Fig. 5. The molecular structure (ORTEP 50% probability level) of 8,ꢁhydrogen atoms are
ꢁ
omitted for clarity. Selected interatomic distances [A] and angles [ ]: Sn1eN1 2.133(3),
Sn1eN2 2.368(3), Sn1eC13 2.205(3), Si1eN1 1.725(3), Si1eC22 1.870(4), Si1eC23
1.862(4), Si1eC24 1.863(4), N1eSn1eN2 104.48(11), N1eSn1eC13 97.22(12),
N2eSn1eC13 76.49(12), C1eN1eSi1 120.4(2), C1eN1eSn1 113.7(2), Si1eN1eSn1
121.00(15).
prepared also by mixing of stannylene {2-[(CH3)2NCH2]C6H4}2Sn
with Li[N(SiMe3)(2,6-i-Pr-C6H3)], where 2-[(CH3)2NCH2]C6H4Li is
isolated as a byproduct.
4.3. (LCN)2Sn[N(H)Ar]2 (5)
The polyhedral structure of 8 around the tin atom is a triangular
pyramid defined by one carbon and two nitrogen atoms with nearly
ideal interatomic angles around the tin atom. The distances
Sn1eN1 and Sn1eC13 bond lengths are slightly higher than in 5,
because of lower oxidation state of the tin atom. On the other hand,
(LCN)2SnBr2 (1.395 g, 2.55 mmol) was dissolved in 30 mL of diethyl
ether and a solution of ArN(H)Li (0.935 g, 5.10 mmol) in 30 mL of
diethyl ether was added dropwise at ꢀ78 ꢁC. The reaction mixture
was then slowly warmed up and stirred for 1 h at room temperature.
Afterwards the reaction mixture was filtered and the filtrate was
evaporated in vacuo to dryness giving the sole product. Yield 1.811 g
(96%). Single crystals of 4 were obtained from saturated diethyl ether
solution at ꢀ30 ꢁC. M.p. 218e221 ꢁC.1H NMR (C6D6, 295 K, ppm): 8.20
(d, 2H, H(6), 3J(119Sn, 1H) ¼ 72.1 Hz), 7.28 (t, 1H, H(4)), 7.23 (m, 2H, H
(3,5)), 7.15 (d, 2H, H(3)), 7.13 (d, 2H, H(30)), 6.98 (t, 1H, H(4)), 6.95 (t,
1H, H(40)), 3.98 (br, 1H, N0H), 3.49 (m, 2H, H(5)), 3.34 (br, 1H, N0H),
3.21 (s, 2H, NCH2), 2.77 (m, 2H, H(50)), 1.93 (s, 6H, N(CH3)2), 1.24 (d,
24H, H(6)). 13C NMR (C6D6, 295 K, ppm): 141.84 (C1, 1J(119Sn,
13C) ¼ 782.5 Hz), 137.3 (C6, 2J(119Sn, 13C) ¼ 47.7 Hz), 129.97 (C4),
129.45 (C3), 127.68 (C5), 123.44 (C40), 66.16 (NCH2, 3J(119Sn,
13C) ¼ 27.6 Hz), 45.94 (N(CH3)2), 29.55 (C50), 28.5 (C50), 24.1 (C70),
22.8 (C70). 15N NMR (C6D6, 295 K, ppm): ꢀ351.3 (CH2N(CH3)2), ꢀ335.1
(NH), ꢀ330.2 (NH). 119Sn NMR (C6D6, 295 K, ppm): ꢀ161.1. Elemental
analysis (%): found: C, 68.0; H, 8.3; N, 7.7; calcd for C42H60N4Sn
(739.66): C, 68.20; H, 8.18; N, 7.57.
ꢁ
the Sn1eN2 bond distance of 2.368(3) A is significantly lower than
in homoleptic stannylene {2-[(CH3)2NCH2]C6H4}2Sn (2.516 and
ꢁ
2.660 A) [14] and is the second shortest SneN distance found for
a tin atom substituted by the 2-[(CH3)2NCH2]C6H4-ligand, to be
ꢁ
compared with 2.258 A for cationic four-coordinated complex
described previously [27].
Reactivity of interest of 8 is limited to low temperatures, because
at higher temperatures, the reaction products can be formulated as
resulting from the reactivity of the parent homoleptic stannylenes
(for example the oxidation with chalcogens) [28] because of the
decomposition of 8 to {2-[(CH3)2NCH2]C6H4}2Sn and Sn[N(SiMe3)
(2,6-i-Pr-C6H3)]2.
To conclude, we investigated both the reactivity and structure of
aminotin compounds containing bulky amino as well as the
C,N-chelating ligands. Both tin(IV) and tin(II) compounds were
prepared including dimeric and monomeric stannylenes. Dimeric
stannylene reacts with water to unique cluster.
4.4. [Ar(H)NSnCl]2 (6)
3. Experimental
A suspension of ArN(H)Li (0.855 g, 4.67 mmol) in 40 mL of
benzene was added dropwise to suspension of SnCl2 (0.885 g,
4.67 mmol) in 20 mL of benzene. The reaction mixture was stirred for
12 h at room temperature. The precipitate was filtered off and the
filtrate was evaporated to dryness in vacuo giving a crude solid
product. The crude product was washed twice with 20 mL of hexane
giving white crystalline 6. Yield 0.799 g (52%). M.p. 227e229 ꢁC. 1H
NMR (Tol-d8, 295 K, ppm): 7.02 (d, 4H, H(30)), 6.89 (t, 2H, H(40)), 5.82
(s, 2H, NH, 2J(119Sn, 1H) ¼ 22.3 Hz), 3.62 and 2.75 (br, 4H, H(50)), 1.14
(d, 24H, H(60)). 119Sn VT-NMR (Tol-d8, ppm): ꢀ22.1 (320 K), ꢀ29.5
(LCN)2SnBr2 (4) [17] and [(Ar)(SiMe3)NSnCl]2 (7) [12] were
prepared according to published procedures. All solvents and
starting compounds were obtained from commercial sources
(SigmaeAldrich). Toluene, THF, diethyl ether, benzene,
n-hexane, n-pentane were dried over and distilled from potas-
sium/sodium alloy with benzophenone, degassed and stored
over potassium mirror under argon. Standard Schlenk tech-
niques were used for all manipulations under an argon
atmosphere.

ꢀ
Z. Padelková et al. / Journal of Organometallic Chemistry 695 (2010) 2651e2657
2656
(295 K), ꢀ47.8 (250 K), ꢀ55.2 (220 K). Elemental analysis (%): found:
C, 43.8; H, 5.6; N, 4.1; calcd for C24H36N2Cl2Sn2 (660.86): C, 43.62; H,
5.49; N, 4.24.
nitromethane (
Me4Sn (0.0 ppm).
d
(
15N) ¼ 0.0), and 119Sn chemical shifts to external
4.7. Crystallography
4.5. LCNSnN[(SiMe3)Ar] (8)
The X-ray data (Table 3) for colorless crystals of 5, 6, 60, 6a and 8
were obtained at 150K using Oxford Cryostream low-temperature
A suspension of LCNLi (0.545 g, 3.86 mmol) in 30 mL of diethyl
ether was added to a solution of 7 (1.555 g, 1.93 mmol) in diethyl
ether (30 mL) at ꢀ30 ꢁC in 20 min. The reaction mixture was
slowly warmed up to room temperature and stirred overnight.
The colour of the mixture changed from light to deep yellow.
Afterwards, the reaction mixture was evaporated to dryness in
vacuo and the solid residue was extracted with hexane
(2 ꢂ 20 mL). Evaporation of volatiles from the hexane extracts
gave yellowish crystalline 8. Yield 1.029 g (54%). M.p. 44e47 ꢁC.
1H NMR (Tol-d8, 300 K, ppm): 7.97 (d, 1H, H(6), 3J(119Sn,
1H) ¼ 62.2 Hz), 7.36 (m, 3H, H(4, 40, 5)), 7.08 (d, 2H, H(30)), 7.01 (d,
1H, H(3)), 3.64 (m, 2H, H(50)), 3.43 (s, 2H, NCH2), 2.34 (s, 3H,
NCH3), 2.27 (s, 3H, NCH3), 1.42 (d, 12H, H(60)), 0.30 (s, 9H, SiMe3).
119Sn NMR (Tol-d8, 300 K, ppm): 326.9. Elemental analysis (%):
found: C, 57.7; H, 7.7; N, 5.4; calcd for C24H38N2SiSn (501.36): C,
57.50; H, 7.64; N, 5.59.
device on a Nonius KappaCCD diffractometer with MoKa radiation
ꢁ
(l
¼ 0.71073 A), a graphite monochromator, and the
4 and c scan
mode. Data reductions were performed with DENZO-SMN [29]. The
absorption was corrected by integration methods [30]. Structures
were solved by direct methods (Sir92) [31] and refined by full
matrix least-square based on F2 (SHELXL97) [32]. Hydrogen atoms
were mostly localized on a difference Fourier map, however to
ensure uniformity of the treatment of the crystal, all hydrogen
atoms were recalculated into idealized positions (riding model) and
assigned temperature factors Hiso(H) ¼ 1.2 Ueq(pivot atom) or of
ꢁ
1.5Ueq for the methyl moiety with CeH ¼ 0.96, 0.97, and 0.93 A for
methyl, methylene and hydrogen atoms in aromatic rings, respec-
ꢁ
tively, 0.86 and 0.82 A for NeH and OeH groups, respectively. There
are disordered solvent benzene molecules in this structure.
Attempts were made to model this disorder or split it into two
positions, but were unsuccessful. PLATON/SQUEZZE [33] was used
to correct the data for the presence of disordered solvent. A
potential total solvent volume of 1566 Å3 was found. 569 electrons
per unit cell worth of scattering were located in the voids. The
calculated stoichiometry of solvent was calculated to be twelve
molecules of benzene per unit cell which results in 504 electrons
per unit cell.
4.6. NMR spectroscopy
The NMR spectra were recorded from solutions in toluene-d8 or
benzene-d6 on a Bruker Avance 500 spectrometer (equipped with
Z-gradient 5 mm probe) at frequencies 1H (500.13 MHz), 13C{1H}
(125.76 MHz), 15N{1H} (50.65 MHz), and 119Sn{1H} (186.50 MHz)
and at 220e320 K. The solutions were obtained by dissolving of
40 mg of each compound in 0.5 ml of deuterated solvents. The
values of 1H chemical shifts were calibrated to internal standard -
4.8. Theoretical calculations
All calculations were conducted at the DFT level using the PBE
functional [34]. Valence electrons were treated using a TZ2P basis
set. Innermost electrons of Sn, Cl, C, and N atoms were emulated
using effective core potentials ECP-SBKJC [35]. Calculations were
made using the PRIRODA program [36].
tetramethylsilane (
d
(1H) ¼ 0.00 ppm) or to residual signals of
benzene (
d
(1H) ¼ 7.16 ppm), toluene (
d
(1H) ¼ 2.09 ppm). The values
of 13C chemical shifts were calibrated to signals of benzene (
d
(
13C)
¼
128.3 ppm), 15N chemical shifts to external neat
Table 3
Crystallographic data for 5, 6, 60, 6a and 8.
Compound
5
60
6
6a
8
Empirical formula
Crystal system
Space group
C
42H60N4Sn
C24H36Cl2N2Sn2
Monoclinic
C2/c
23.6781(9)
9.4303(12)
12.1867(8)
109.46(6)
4
C54H78Cl2N2Sn2
Monoclinic
P 21/c
24.9031(12)
8.8753(14)
36.3628(13)
133.099(9)
8
C36H55Cl6N3O7Sn10$C6H6
Trigonal
C24H38N2SiSn$4C6H6
Orthorhombic
Pbca
15.6031(14)
16.1323(18)
19.8168(15)
90
Monoclinic
P 21/n
P ꢀ3
ꢁ
a (A)
11.0461(2)
19.5800(3)
19.0449(3)
105.6781(8)
4
17.0032(12)
17.0032(18)
22.3289(12)
ꢁ
b (A)
ꢁ
c (A)
b
(ꢁ)
90,
2
g
¼ 120
Z
8
3
ꢁ
V (A )
3965.82(11)
1.239
2565.6(2)
1.711
5868.2(11)
1.584
5590.5(11)
1.303
4988.1(8)
1.335
Dc/g cmꢀ3
Crystal size (mm)
Crystal shape
m
0.32 ꢂ 0.30 ꢂ 0.20
Colorless prism
0.677
0.29 ꢂ 0.15 ꢂ 0.15
Colorless block
2.169
0.17 ꢂ 0.15 ꢂ 0.11
Colorless plate
1.902
0.41 ꢂ 0.31 ꢂ 0.12
Colourless plate
2.363
0.25 ꢂ 0.14 ꢂ 0.14
Yellow block
1.084
(mmꢀ1
)
F (000)
h; k; l range
range/ꢁ
Reflections measured
1560
1312
2792
2060
2080
ꢀ14, 14; ꢀ25, 25; ꢀ24, 24 ꢀ29, 30; ꢀ12, 12; ꢀ15, 15 ꢀ32, 32; ꢀ11, 11; ꢀ47, 47 ꢀ22, 18; ꢀ18, 22; ꢀ29, 25 ꢀ17, 20; ꢀ16, 20; ꢀ25,22
q
3.04; 27.51
56173
9096 (0.0281)
3.12; 27.5
16777
2916 (0.1253)
1785
2.55; 27.5
121477
13483 (0.0517)
10191
2.29; 27.5
24924
8294 (0.1089)
4869
3.26; 27.5
23595
5703 (0.0744)
3795
a
e independent (Rint
)
e observed [I > 2
s(I)] 6780
Parameters refined
445
136
595
190
253
ꢁꢀ3
Max/min Dr/eA
0.838/ꢀ0.455
1.565/ꢀ2.698
1.069/ꢀ1.196
0.974/ꢀ1.296
1.565/ꢀ2.698
b
GOF
R
1.018
1.056
1.095
0.916
1.068
c/wR c
0.0268/0.0590
0.0646/0.1214
0.0397/0.0629
0.0531/0.1259
0.0450/0.0626
a
b
c
Rint ¼ SjF2o ꢀ F2o,meanj/SF2o.
½
GOF ¼ [S(w(F2o ꢀ F2c)2)/(Ndiffrs ꢀ Nparams)] for all data.
R(F) ¼ SkFoj ꢀ jFck/SjFojfor observed data, wR(F2) ¼ [S(w(Fo2 ꢀ Fc2)2)/(Sw(Fo2)2)] for all data.
½

ꢀ
Z. Padelková et al. / Journal of Organometallic Chemistry 695 (2010) 2651e2657
2657
[13] A.H. Cowley, D.M. Giolando, R.A. Jones, C.M. Nunn, J.M. Power, Polyhedron 7
(1988) 1317.
Acknowledgements
[14] (a) K. Angermund, K. Jonas, C. Kruger, J.L. Latten, Y.-H. Tsay, J. Organomet.
Chem. 353 (1988) 17;
The Pardubice group would like to thank the Grant Agency of Czech
Academy of Science (KJB401550802), the Science Foundation (P106/
10/0924) and the Ministry of Education of the Czech Republic
(VZ0021627501) for financial support.
(b) J.T.B.H. Jastrzebski, G. van Koten, Adv. Organomet. Chem. 35 (1993) 241;
ꢀ
ꢀ
ꢀ
ꢁꢀ ꢀ
(c) Z. Padelková, M.S. Nechaev, Z. Cernosek, J. Brus, A. Ruzicka, Organome-
tallics 27 (2008) 5303;
ꢀ
ꢀ
ꢀ
(d) Z. Padelková, H. Vankátová, I. Císarová, M.S. Nechaev, T.A. Zevaco,
O. Walter, A. Ruzicka, Organometallics 28 (2009) 2629;
(e) J. Bares, P. Richard, P. Meunier, N. Pirio, Z. Padelková, Z. Cernosek,
ꢁꢀ ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Appendix A. Supplementary material
ꢀ
ꢁꢀ ꢀ
I. Císarová, A. Ruzicka, Organometallics 28 (2009) 3105;
ꢀ
ꢀ
ꢁꢀ ꢀ
(f) Z. Padelková, M.S. Nechaev, A. Lycka, J. Holubová, T.A. Zevaco, A. Ruzicka,
Eur. J. Inorg. Chem. 14 (2009) 2058.
CCDC Nos. 765424, 765420, 765421, 765423 and 765422 contain
crystallographic data for the structural analysis of compound 5, 60,
6, 6a and 8, respectively. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.ccdc.
cam.ac.uk/data_request/cif.
[15] (a) T.P. Lockhart, J. Organomet. Chem. 287 (1985) 179;
(b) B. Wrackmeyer, Annu. Rep. NMR Spectrosc. 16 (1985) 73;
(c) B. Wrackmeyer, Annu. Rep. NMR Spectrosc. 38 (1999) 203.
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
[16] J. Bares, V. Sourek, Z. Padelková, P. Meunier, N. Pirio, I. Císarová, J. Holecek,
ꢁꢀ ꢀ
A. Ruzicka, Collect. Czech. Chem. Commun. 75 (2010) 121.
[17] (a) G. van Koten, J.T.B.H. Jastrzebski, J.G. Noltes, J. Organomet. Chem. 177
(1979) 283;
References
ꢁꢀ ꢀ
ꢀ
ꢀ
(b) A. Ruzicka, V. Pejchal, J. Holecek, A. Lycka, K. Jacob, Collect. Czech. Chem.
Commun. 63 (1998) 977;
[1] A.G. Davies, Organotin Chemistry. VCH, Weinheim, FRG, 1997
(Chapter 16).
[2] M.F. Lappert, B. Prokai, Adv. Organomet. Chem. 5 (1967) 225.
[3] L.S. Khaikin, A.V. Belyakov, G.S. Koptev, A.V. Golubinskii, L.V. Vilkov, J. Mol.
Struct. 66 (1980) 0191.
[4] S. Diemer, H. Nöth, K. Polborn, W. Storch, Chem. Ber. 125 (1992) 389.
[5] H. Puff, D. Hänssgen, N. Beckermann, A. Roloff, W. Schuh, J. Organomet. Chem.
373 (1989) 37.
[6] (a) H. Grützmacher, H. Pritzkow, F.T. Edelmann, Organometallics 10 (1991) 23;
(b) G. Ossig, A. Meller, S. Freitag, R. Herbst-Irmer, J. Chem. Soc. Chem. Com-
mun. (1993) 497;
(c) H. Grützmacher, H. Pritzkow, Angew. Chem. Int. Ed. Engl. 30 (1991) 1017.
[7] B. Wrackmeyer, E. Kupce, Top. Phys. Org. Chem. (1992) 4.
[8] For selected reviews on compounds with a tin atom in a lower oxidation state
see: (a) M. Kira, J. Organomet. Chem. 689 (2004) 4475;
& 2004,
ꢀ
ꢀ
ꢀ
ꢁꢀ ꢀ
ꢀ
(c) P. Novák, Z. Padelková, L. Kolárová, I. Císarová, A. Ruzicka, J. Holecek, Appl.
Organomet. Chem. 19 (2005) 1101.
[18] H. Chen, R.A. Bartlett, H.V. Rasika Dias, M.M. Olmstead, P.P. Power, Inorg.
Chem. 30 (1991) 3390.
[19] Y. Tang, A.M. Felix, L.N. Zakharov, A.L. Rheingold, R.A. Kemp, Inorg. Chem. 43
(2004) 7239.
[20] M. Veith, M. Jarczyk, V. Huch, Chem. Ber 121 (1988) 347.
[21] M. Veith, B. Schillo, V. Huch, Angew. Chem. Int. Ed. Engl. 38 (1999) 182.
[22] M. Veith, P. Hobein, R. Rosler, Z. Naturforsch., B. J. Chem. Sci. 44 (1989) 1067.
[23] A.G. Avent, C. Drost, B. Gehrhus, P.B. Hitchcock, M.F. Lappert, Z. Anorg. Allg.
Chem. 630 (2004) 2090.
[24] V.N. Khrustalev, I.V. Glukhov, I.V. Borisova, N.N. Zemlyansky, Appl. Organo-
met. Chem. 21 (2007) 551.
ꢀ
ꢁꢀ ꢀ
[25] J. Turek, Z. Padelková, M.S. Nechaev, A. Ruzicka, Eur, J. Inorg. Chem. 695 (2010)
1843.
(b) K.W. Klinkhammer, in: Z. Rappoport (Ed.), Chemistry of Organic Germa-
nium, Tin and Lead Compounds, vol. 2, Wiley, NewYork, 2002, pp. 283e357;
(c) N.J. Hill, R. West, J. Organomet. Chem. 689 (2004) 4165;
(d) B. Gehrhus, M.F. Lappert, J. Organomet. Chem. 617 (2001) 209;
(e) O. Kühl, Coord. Chem. Rev. 248 (2004) 411;
[26] J.R. Babcock, L. Liable-Sands, A.L. Rheingold, L.R. Sita, Organometallics 18
(1999) 4437.
ꢀ
ꢀ
ꢁꢀ ꢀ
ꢀ
ꢀ
[27] J. Turek, Z. Padelková, Z. Cernosek, M. Erben, A. Lycka, M.S. Nechaev,
ꢀ
I. Císarová, A. Ruzicka, J. Organomet. Chem. 694 (2009) 3000.
[28] Z. Padelková, I. Císarová, M.S. Nechaev, A. Ruzicka, J. Organomet. Chem. 694
(2009) 2871.
ꢀ
ꢀ
ꢁꢀ ꢀ
(f) N.N. Zemlyanskii, I.V. Borisova, M.S. Nechaev, V.N. Khrustalev, V.V. Lunin,
M.Yu Antipin, Yu.A. Ustynyuk, Russ. Chem. Bull. Int. Ed. 53 (2004) 980;
(g) A.V. Zabula, F.E. Hahn, Eur. J. Inorg. Chem. (2008) 5165;
(h) V.Ya Lee, A. Sekiguchi, Eur. J. Inorg. Chem. 7 (2005) 1209;
(i) Y. Mizuhata, T. Sasamori, N. Tokitoh, Chem. Rev. 109 (2009) 3483.
[9] For selected reviews on N-heterocyclic carbenes see: (a) S.P. Nolan (Ed.),
N-Heterocyclic Carbenes in Synthesis, Wiley-VCH, Weinheim, Germany,
2006;
(b) F. Glorius, N-Heterocyclic Carbenes in Transition Metal Catalysis.
Springer, Berlin, 2007;
(c) S.T. Liddle, I.S. Edworthy, P.L. Arnold, Chem. Soc. Rev. 36 (2007) 1732.
[10] H. Cox, P.B. Hitchcock, M.F. Lappert, L.J.-M. Pierssens, Angew. Chem. Int. Ed.
Engl. 43 (2004) 4500.
[29] Z. Otwinowski, W. Minor, Methods Enzymol. 276 (1997) 307.
[30] P. Coppens, in: F.R. Ahmed, S.R. Hall, C.P. Huber (Eds.), Crystallographic
Computing, Munksgaard, Copenhagen, 1970, pp. 255e270.
[31] A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, J. Appl. Crystallogr. 26
(1993) 343.
[32] G.M. Sheldrick, SHELXL-97. University of Göttingen, Göttingen, 1997;
[33] A.L. Spek, Acta Crystallogr. Sect. A 46 (1990) C34.
[34] (a) J.P. Perdew, K. Burke, M. Ernzerhoff, Phys. Rev. Lett. 77 (1996) 3865;
(b) M. Ernzerhoff, G.E. Scuseria, J. Chem. Phys. 110 (1999) 5029;
(c) C. Adamo, V. Barone, J. Chem. Phys. 110 (1999) 6158.
[35] (a) W.J. Stevens, H. Basch, M. Krauss, J. Chem. Phys. 81 (1984) 6026;
(b) W.J. Stevens, M. Krauss, H. Basch, P.G. Jasien, Can. J. Chem. (1992) 612;
(c) T.R. Cundari, W.J. Stevens, J. Chem. Phys. 98 (1993) 5555.
[36] (a) D.N. Laikov, Chem. Phys. Lett. 281 (1997) 151;
[11] R.W. Chorley, P.B. Hitchcock, B.S. Jolly, M.F. Lappert, G.A. Lawless, Chem.
Commun. (1991) 1302.
[12] M. Brynda, R. Herber, P.B. Hitchcock, M.F. Lappert, I. Nowik, P.P. Power,
(b) D.N. Laikov, Y.A. Ustynyuk, Russ. Chem. Bull. Int. Ed. 54 (2005) 820.
ꢁꢀ ꢀ
A.V. Protchenko, A. Ruzicka, J. Steiner, Angew. Chem. Int. Ed. Engl. 45 (2006) 4333.