To Rearrange or not to Rearrange: Reactivity of NHCs towards Chloro- and Hydrostannanes R2SnCl2(R = Me, Ph) and Ph3SnH

Article abstract of DOI:10.1002/zaac.201600271

The reaction of 1,3-diisopropylimidazolin-2-ylidene (iPr₂Im) with diphenyldichlorostannane and dimethyldichlorostannane, respectively, leads to the formation of the adducts (iPr₂Im)·SnPh₂Cl₂(1) and (iPr₂Im)·SnMe₂Cl₂(2). These compounds are stable in solution to temperatures up to 80 °C for several days and rearrangement to backbone-tethered bis(imidazolium) salts or ring expansion reaction to six membered heterocyclic rings was not observed. The reaction of iPr₂Im with triphenylstannane Ph₃SnH leads to reductive dehydrocoupling of the stannane to yield distannane Sn₂Ph₆and iPr₂ImH₂. Thus, the reactivity of these tin compounds is completely different compared to those of the lighter congener silicon, for which rearrangement (chlorides) and NHC ring expansion (hydrides) was reported earlier.

Full text of DOI:10.1002/zaac.201600271

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DOI: 10.1002/zaac.201600271
To Rearrange or not to Rearrange: Reactivity of NHCs towards Chloro- and
Hydrostannanes R2SnCl2 (R = Me, Ph) and Ph3SnH
Heidi Schneider,[a] Mirjam J. Krahfuß,[a] and Udo Radius*[a]
Keywords: N-heterocyclic carbene; Stannanes; Reductive dehydrocoupling; Tin
Abstract. The reaction of 1,3-diisopropylimidazolin-2-ylidene (iPr2Im) bered heterocyclic rings was not observed. The reaction of iPr2Im with
with diphenyldichlorostannane and dimethyldichlorostannane, respec-
triphenylstannane Ph3SnH leads to reductive dehydrocoupling of the
tively, leads to the formation of the adducts (iPr2Im)·SnPh2Cl2 (1) and stannane to yield distannane Sn2Ph6 and iPr2ImH2. Thus, the reactivity
(iPr2Im)·SnMe2Cl2 (2). These compounds are stable in solution to tem- of these tin compounds is completely different compared to those of
peratures up to 80 °C for several days and rearrangement to backbone- the lighter congener silicon, for which rearrangement (chlorides) and
tethered bis(imidazolium) salts or ring expansion reaction to six mem-
NHC ring expansion (hydrides) was reported earlier.
ceptor orbital located at the carbene carbon atom, which makes
them – similar to most of the transition metal complexes – to
Lewis acids and Lewis bases in one molecule.[1] Thus, they are
capable to undergo oxidative addition reactions of non-polar
element hydride bonds.
Introduction
The application of N-heterocyclic carbenes (NHCs) and re-
lated molecules[1] is not restricted to their use as spectator li-
gands in transition-metal chemistry, as has been shown over
the last two decades. The importance of this class of com-
pounds, for example, in main-group element chemistry is con-
stantly growing.[2] Reactions of carbenes even with simple
main-group element compounds reveal an enormous richness
and lead into a variety of reaction pathways.[3] In dependence
on the nature of the main-group element compound, and on the
electronic and steric properties of the carbene used, different
reactivity may be observed. This can be exemplified for the
reactions of singlet carbenes with main-group element hy-
drides (Scheme 1). Because of the basic character of carbenes,
the reaction with (even rather weak) Brønsted acids like
alcohols or hydrogen halides leads to deprotonation of the sub-
strate with formation of the corresponding imidazolium salt
[Scheme 1 (i)].[4] In contrast, the reaction of NHCs with less
acidic and more basic element hydrides leads to a completely
different reaction pattern. We have shown for group 15 ele-
ment hydrides, for example, that secondary and primary phos-
phines may be converted with NHCs into diphosphines or cy-
clooligophosphines by reductive dehydrocoupling, using the
carbenes as E–H activator and hydrogen acceptor [Scheme 1
(ii)].[5] Furthermore, we and others have shown that NHCs and
related molecules such as CAACs and diamidocarbenes can
activate element hydrogen bonds, for example in boranes (B–
H), silanes (Si–H), and phosphines (P–H) [Scheme 1 (iii)].[6]
Singlet ground state carbenes possess an energetically high ly-
ing occupied donor orbital and an accessible unoccupied ac-
Scheme 1. NHC-mediated reactions of main-group element hydrogen
compounds.
In addition, ring expansion reactions (RER) of NHCs have
been established for certain group 2, 13, and 14 hydrides over
the last few years [Scheme 1 (iv)]. It has been demonstrated
that these RERs follow E–H bond activation reactions at
higher temperatures, for example for element hydrides of ber-
yllium, boron, and silicon.[7] Computational [8] and experimen-
tal studies on the mechanism of RERs have shown that the
* Prof. Dr. U. Radius
E-Mail: u.radius@uni-wuerzburg.de
[a] Institut für Anorganische Chemie
Julius-Maximilians-Universität Würzburg
Am Hubland
97074 Würzburg, Germany
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reaction progress can be divided into four steps that include (i) thus interested in the reactivity of NHCs toward tin hydrides
adduct formation between the Lewis basic NHC and the Lewis equipped with simple substituents such as methyl or phenyl.
acidic element hydride, (ii) hydride migration from the element Herein, we wish to report first investigations on the reactivity
hydride to the NHC carbene carbon atom (= oxidative addition of iPr2Im or iPr2Me2Im with Ph2SnCl2, Me2SnCl2, and
of E–H), (iii) C–N bond cleavage and ring expansion of the Ph3SnH.
NHC with insertion of the main-group element moiety into the
NHC ring, and (iv) stabilization of the ring expanded NHC,
Results and Discussion
for example via migration of another hydrogen atom to the
(former) NHC carbene carbon atom. For the reaction of iPr2Im
(iPr2Im = 1,3-diisopropylimidazolin-2-ylidene) with Ph3SiH,
for example, we have isolated and (also structurally) charac-
terized the ring expansion product A (Scheme 2).[7c] In con-
trast to that, we have also shown that the reaction of the NHC
iPr2Im with diphenyldichlorosilane Ph2SiCl2 enters a com-
pletely different pathway and leads to the adduct (iPr2Im)
·SiPh2Cl2 (Scheme 2 B), which rearranges to the backbone
tethered bis(imidazolium) salt [(aHiPr2Im)2SiPh2]2+2Cl– [“a”
denotes “abnormal” coordination of the NHC; Scheme 1 (v);
Scheme 2 C].[9] Although the mechanism of this reaction is
not clear yet, we currently assume that the rearrangement from
the “normal” to the “abnormal” coordination mode is triggered
by protonation/deprotonation steps in (iPr2Im)·SiPh2Cl2 with
concomitant dissociation of a chloride substituent and coordi-
nation of a second NHC, which rearranges in turn.
The reactivity of the N-heterocyclic carbene iPr2Im with
Ph2SnCl2 and Me2SnCl2 is summarized in Scheme 3. The
NHC iPr2Im reacts cleanly at –78 °C in thf or toluene with
diphenyldichlorostannane and dimethyldichlorostannane to af-
ford the NHC adducts (iPr2Im)·SnPh2Cl2 (1) and (iPr2Im)·
SnMe2Cl2 (2) in form of white solids. Compounds 1 and 2
were isolated in good yield (70% for 1, 67% for 2) and charac-
terized using multinuclear NMR spectroscopy, elemental
analysis and X-ray diffraction. In the 13C NMR spectra of 1
and 2 the resonances of the NHC carbene carbon atoms are
significantly high field shifted to 163.7 ppm for (iPr2Im)·
SnPh2Cl2 and to 161.3 ppm for (iPr2Im)·SnMe2Cl2 compared
to iPr2Im (δ = 211.6 ppm). The 119Sn{1H} NMR spectrum of
1 shows in accordance with literature known (iPr2Me2Im)·
SnPh2Cl2 (–314.4 ppm in CDCl3)[10]
a
resonance at
–317.7 ppm (1) in deuterobenzene, significantly shifted from
the resonance of Ph2SnCl2 at –26.4 ppm. The 119Sn NMR
spectrum of compound 2 gives rise to a resonance at
–227.0 ppm, also shifted from the signal of Me2SnCl2 (δ =
139.8 ppm). Signal pattern and the integration of the reso-
nances in the proton NMR account for the coordination of one
NHC to the central tin atom via the carbene carbon atom.
Scheme 3. The reactivity of the N-heterocyclic carbene iPr2Im with
Ph2SnCl2 and Me2SnCl2.
Scheme 2. The reactivity the NHC iPr2Im towards chloro- and hydro-
silanes.
The molecular structures of compounds 1 and 2 were deter-
mined by X-ray diffraction and are presented in Figure 1 and
Since the investigations in our group have clearly estab- Figure 2. Single crystals of 1 were grown from a saturated n-
lished significant differences in the reactivity of NHCs with hexane solution of this compound at –30 °C. (iPr2Im)·
silicon hydrides and chlorides, which ended in both cases in SnPh2Cl2 (1) crystallizes in the orthorhombic space group
novel pathways, we were interested to explore the reactivity P212121 with one molecule in the asymmetric unit. The central
of NHCs such as iPr2Im with stannanes and tin chlorides. tin atom is distorted trigonal bipyramidal coordinated with two
Some NHC adducts of tin organyl halides are already phenyl groups, two chloride substituents, and one NHC ligand.
known,[10] but none of them was tested on their behavior at The two chloride atoms occupy the axial positions of the bi-
higher temperatures. It is currently unknown if these molecules pyramid, whereas the two phenyl groups and iPr2Im occupy
rearrange or not. For tin hydrides, Wesemann et al. reported the the equatorial positions. The distance between the NHC carb-
NHC-mediated dehydrocoupling of organotin dihydride (trip) ene carbon atom C(1) and the tin atom of 2.1773(19) Å is in
2SnH2 and trihydride tripSnH3 with the sterically demanding perfect agreement with the distance found for (iPr2Me2Im)·
trip (trip = 2,4,6-triisopropylphenyl) substituent using 1,3-di- SnPh2Cl2 (2.179(3) Å],[10] the tin aryl and Sn–Cl bond lengths
ethyl-4,5-dimethylimidazolin-2-ylidene (Et2Me2Im) as the show no significant deviations as well. Both chloride substitu-
carbene.[11] These reactions led to compounds with Sn–Sn ents are bend towards the NHC ligand with an angle Cl1–Sn–
bonds such as trip2(H)Sn–Sn(H)trip2 and Sn6trip6. We were Cl2 of 163.037(18)°, significantly smaller than 180°.
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both tin adducts (iPr2Im)·SnPh2Cl2 (1) and (iPr2Im)·SnMe2Cl2
(2) in thf or benzene for several days to 80 °C did not result in
any change of the NMR spectra or formation of any insoluble
precipitate. However, small amounts of imidazolium salt
[iPr2ImH]+ Cl– were detected after several days. For (iPr2Im)
·SiPh2Cl2 it was observed that [(aHiPr2Im)2SiPh2]2+2Cl– pre-
cipitated in form of a white solid at similar conditions.[9] These
findings account for a much larger stability of the NHC ad-
ducts 1 and 2 of the more Lewis-acidic tin compounds R2SnCl2
compared to the corresponding silicon compound Ph2SiCl2,
and thus no transformation of the carbene from its “normal”
Figure 1. Molecular structure of (iPr2Im)·SnPh2Cl2 (1) in the solid
state (ellipsoids set at 50% probability level). Hydrogen atoms are coordination mode to an “abnormal” coordination mode was
omitted for clarity. Selected bond lengths /Å and bond angles /°: Sn–
C1 2.1773(19), Sn–C11 2.1454(19), Sn–C21 2.1465(19), Sn–Cl1
The reaction of triphenylstannane Ph3SnH with iPr2Im or
2.5479(5), Sn–Cl2 2.5381(5); C1–Sn–C11 119.45(7), C1–Sn–C21
detected.
iPr2Me2Im in the stoichiometric ratio of 2:1 for 18 h at 80 °C
116.47(7), C1–Sn–Cl1 81.50(5), C1–Sn–Cl2 81.54(5), C11–Sn–C21
in benzene or toluene leads with formation of iPr2ImH2 (4) or
iPr2Me2ImH2 (5) to the dehydrocoupling product Ph6Sn2 (3)
in good yield of 60% and 69%, respectively (see Scheme 4).
To prove that the reaction pathway is independent on substitu-
ents on the backbone, we tested for this reaction both with
backbone methylated iPr2Me2Im, as the Wesemann group did,
and backbone unsubstituted iPr2Im. However, in both cases
dehydrocoupling of Ph3SnH to the distannane 3 was observed
in quantitative yield, if performed on NMR scale. The distan-
124.08(7), C11–Sn–Cl1 93.74(8), C11–Sn–Cl2 94.12(8), C21–Sn–Cl1
93.54(8), C21–Sn–Cl2 94.46(8), Cl1–Sn–Cl2 163.034(18).
1
nane 3 was characterized by H and 119Sn NMR spectroscopy
(resonance at –141.3 ppm for Ph6Sn2 [12]) and elemental analy-
sis. The hydrogenated carbenes, e.g. iPr2ImH2 (4) can be easily
detected in the proton NMR spectrum. Compound 4 reveals a
sharp singlet at δ = 3.98 ppm for the two hydrogen atoms at
the former carbene carbon atom. The corresponding septet of
the methine protons was detected at δ = 2.48 ppm, resonances
for the protons of the backbone of the NHC and the methyl
groups of the isopropyl arms are observed as a singlet at 5.51
and as a doublet at δ = 0.96 ppm. Similarly, the 13C NMR
spectrum reveals a resonance for the methylene unit of iP-
r2ImH2 (4) at δ = 73.9 ppm, significantly shifted from the reso-
nance of the NHC carbene carbon atom of iPr2Im at δ =
211.9 ppm.
Figure 2. Molecular structure of (iPr2Im)·SnMe2Cl2 2 in the solid state
(ellipsoids set at 50% probability level). Hydrogen atoms are omitted
for clarity. Selected bond lengths /Å and bond angles /°: Sn–C1
2.1908(55), Sn–C11 2.1246(62), Sn–C12 2.1293(60), Sn–Cl1
2.5689(16), Sn–Cl2 2.5820(16); C1–Sn–C11 119.424(231), C1–Sn–
C12 118.701(213), C1–Sn–Cl1 84.304(157), C1–Sn–Cl2 83.552(145),
C11–Sn–C12 121.866(239), C11–Sn–Cl1 94.306(176), C11–Sn–Cl2
91.359(178), C12–Sn–Cl1 92.148(166), C12–Sn–Cl2 93.973(168),
Cl1–Sn–Cl2 167.851(45).
Single crystals of 2 suitable for X-ray diffraction were
grown by recrystallization from toluene. The adduct (iPr2Im)·
SnMe2Cl2 (2) crystallizes in the monoclinic space group P21/c
with one molecule in the asymmetric unit. Similar to (iPr2Im)·
SnPh2Cl2 (1), the central tin atom is trigonal bipyramidally
surrounded by two methyl groups, two chloride substituents,
and the NHC ligand. The NHC–C(1)–Sn distance of
2.1908(55) Å is slightly longer than that of compound 1,
whereas the tin methyl bond lengths as well as the tin chloride
Scheme 4. NHC-mediated reductive dehydrocoupling of Ph3SnH to
Ph6Sn2 with the NHC as hydrogen acceptor.
No formation of an adduct of the type (iPr2Im)·SnPh3H was
bond distances are almost identical to those found for com- observed spectroscopically, neither at room temperature, nor if
pound 1. The axially coordinated chloride substituents are also a stoichiometric ratio Ph3SnH:NHC of 1:1 was used. Also, no
strongly bend towards the NHC ligand with an angle Cl1–Sn– ring expanded product was detected for the reaction of iPr2Im
Cl2 of 167.851(46)°. However, the trigonal plane is ideally with Ph3SnH, which is in significant contrast to the reactivity
arranged with a sum of the angles between the equatorial li- we have found for the lighter homologue Ph3SiH. Instead, de-
gands (NHC, and the two methyl groups) of 359.99°.
hydrocoupling of the stannane prevails, which confirms the
Compounds 1 and 2 are in contrast to the silicon analogue findings of Wesemann et al. on the reactivity of NHC with aryl
(iPr2Im)·SiPh2Cl2 readily soluble in solvents like benzene or stannanes with bulky aryl substituents.[11] In dependence on
toluene and are stable even after prolonged heating to the boil- the ratio of carbene to stannane used, Wesemann’s group de-
ing point of these solvents. Continuous heating of solutions of tected adduct formation and subsequent dehydrocoupling to
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(iPr2Im)·SnMe2Cl2 (2): iPr2Im (209 mg, 1.37 mmol) was added at
yield distannane Sn2H2trip4 (starting from trip2SnH2) or tin
–78 °C to a solution of dimethyldichlorostannane (300 mg, 1.37 mmol)
in thf (20 mL) and allowed to warm up to room temperature overnight.
All volatiles were removed in vacuo and the residue was suspended in
n-hexane (20 mL). The precipitate was filtered off and dried in vacuo
to afford 339 mg (911 μmol, yield: 67%) of a colorless powder.
C11H22Cl2N2Sn [371.92 g·mol–1]: calcd. (found): C: 35.52 (33.59), H:
cluster compounds such as Sn6trip6 (starting from tripSnH3).
As observed here or for the dehydrocoupling of primary or
secondary phosphines the NHC acts simultaneously as Sn–H
activator and hydrogen acceptor to form hydrogenated
NHC·H2.
1
5.96 (5.80), N: 7.53 (6.87)%. H NMR (400.4 MHz, C6D6, 298 K): δ
3
= 1.16 (s, 6 H, Sn-CH3), 1.54 (d, 12 H, JHH = 6.7 Hz, iPr–CH3), 5.13
(sept, 2 H, 3JHH = 6.7 Hz, iPr–CH), 7.60 (s, 2 H, NCHCHN). 13C{1H}
NMR (100.7 MHz, C6D6, 298 K): δ = 11.7 (Sn–CH3), 23.0 (iPr–CH3),
32.8 (iPr–CH), 119.0 (NCHCHN), 161.5 (NCN). 119Sn{1H}
(149.3 MHz, C6D6, 298 K): δ = –227.0 ppm.
Conclusions
To summarize, we have shown that the reactivity of aryl tin
hydrides and aryl tin chlorides with N-heterocyclic carbenes
such as iPr2Im differs significantly from the situation we have
found for the corresponding silicon compounds.[7c,9] The reac-
tion of Ph2SiCl2 with iPr2Im leads to formation of an adduct
(iPr2Im)·SiPh2Cl2, which is thermally unstable and rearranges
at elevated temperatures to a backbone-silicon-tethered bis(im-
idazolium) salt. In contrast to this, the novel NHC adducts
(iPr2Im)·SnR2Cl2 [R = Ph (1) Me (2)] remain intact upon pro-
longed heating to higher temperatures over several days, which
accounts for a much higher stability of these adducts compared
to their silicon analogues. For the reaction of iPr2Im with the
silicon compound Ph3SiH we have observed ring expansion
with incorporation of Ph2Si into the five membered ring of the
NHC before. In sharp contrast to this we report here dehy-
drocoupling of the tin hydride Ph3SnH with Sn–Sn bond for-
mation using iPr2Im as hydrogen acceptor. This interesting re-
action seems to be rather general for tin hydrides and has to
be exploited in the future.
Ph6Sn2 (3): Synthesis via reaction of Ph3SnH with iPr2Im: Tri-
phenylstannane (779 mg, 2.22 mmol) was added at room temperature
to a solution of iPr2Im (169 mg, 1.11 mmol) in toluene (10 mL) and
heated to 100 °C for 1 d. During this time a colorless precipitate was
formed, which was filtered off, washed with n-hexane (5 mL) twice
and dried in vacuo to afford 465 mg (664 μmol, yield: 60%) Ph6Sn2
as colorless powder. Synthesis via reaction of Ph3SnH with iPr2Me2Im:
Triphenylstannane (779 mg, 2.22 mmol) was added at room tempera-
ture to a solution of iPr2Me2Im (200 mg, 1.11 mmol) in toluene
(10 mL) and heated to 100 °C for 1 d. During this time a colorless
precipitate was formed, which was filtered off, washed with n-hexane
(5 mL) twice and dried in vacuo to afford 537 mg (767 μmol, yield:
69%) Ph6Sn2 in form of a colorless powder. C21H26Cl2N2Sn [700.06 g·
1
mol–1]: calcd. (found): C: 61.77 (61.32), H: 4.32 (4.49)%. H NMR
(400.4 MHz, C6D6, 298 K): δ = 7.08–7.10 (m, 18 H, aryl-CH), 7.60–
7.74 (m, 12 H, aryl-CH). 13C{1H} NMR (100.7 MHz, C6D6, 298 K):
δ = 129.2, 137.9, 139.5 (aryl-C); 119Sn{1H} NMR (149.3 MHz, C6D6,
298 K): δ = –141.3 ppm.
NMR Spectroscopic Experiments: Conversion of 1 equiv. of iPr2Im
and 2 equiv. of Ph3SnH in C6D6: Triphenylstannane (103 mg,
293 μmol) was added at room temperature to a solution of iPr2Im
(22.0 mg, 145 μmol) in C6D6 (700 μL) and heated to 80 °C for 18 h.
Identified products: iPr2ImH2 (4): 1H NMR (400.4 MHz, C6D6,
Experimental Section
General Procedure: All reactions and subsequent manipulations were
performed in an argon atmosphere using standard Schlenk tech-
niques.[13] Elemental analysis were performed in the microanalytical
laboratory at the department of the University Würzburg with an Ele-
mentar vario micro cube. NMR spectra were recorded with a Bruker
Avance 400 (1H, 400.4 MHz; 13C, 100.7 MHz; 119Sn, 149.3 MHz),
using C6D6 as the solvent and referenced to the internal C6D5H signal
(1H, δ = 7.16, 13C, δ = 128.1 ppm). The NHCs iPr2Im (1,3-diisoprop-
ylimidazolin-2-ylidene)[14] and iPr2Me2Im (1,3-diisopropyl-4,5-di-
methylimidazolin-2-ylidene)[15] were prepared according to published
procedures. Ph3SnH was prepared by reduction of Ph3SnCl with Li-
AlH4 and purified by fractionated distillation. Ph2SnCl2 and Me2SnCl2
were purchased from ABCR and used as received.
3
298 K): δ = 0.96 (d, 12 H, JHH = 6.4 Hz, iPr-CH3), 2.48 (sept, 2 H,
3JHH = 6.4 Hz, iPr-CH), 3.98 (s, 2 H, NCH2N), 5.51 (s, 2 H,
NCHCHN). 13C NMR (100.7 MHz, C6D6, 298 K): δ = 21.1 (iPr-CH3),
52.6 (iPr-CH), 73.8 (NCH2N), 118.5 (NCHCHN). Ph6Sn2 (3): 1H
NMR (400.4 MHz, C6D6, 298 K): δ = 7.08–7.11 (m, 18 H, aryl-CH),
7.60–7.75 (m, 12 H, aryl-CH). 13C NMR (100.7 MHz, C6D6, 298 K):
δ = 129.2 (aryl-C), 137.9 (aryl-C), 139.5 (aryl-Cipso). 119Sn{1H} NMR
(149.3 MHz, C6D6, 298 K): δ = –141.4. Conversion of 1 equiv. of
iPr2Me2Im and 2 equiv. of Ph3SnH in C6D6: Triphenylstannane
(62.2 mg, 177 μmol) was added at room temperature to a solution of
iPr2Me2Im (16.0 mg, 88.7 μmol) in C6D6 (700 μL) and heated to 80 °C
(iPr2Im)·SnPh2Cl2 (1): iPr2Im (133 mg, 873 μmol) was added at for 18 h. Identified products: iPr2Me2ImH2 (5): 1H NMR
3
–78 °C to a solution of diphenyldichlorostannane (300 mg, 873 μmol) (400.4 MHz, C6D6, 298 K): δ = 0.98 (d, 12 H, JHH = 6.7 Hz, iPr–
in thf (20 mL)and allowed to warm up to room temperature overnight. CH3), 1.61 [s, 6 H, NC(CH3)C(CH3)N], 3.32 (sept, 2 H, 3JHH = 6.7 Hz,
All volatiles were removed in vacuo and the residue was suspended in
iPr–CH), 4.21 (s, 2 H, NCH2N). 13C NMR (100.7 MHz, C6D6, 298 K):
n-hexane (20 mL). The precipitate was filtered off and dried in vacuo δ = 18.4 (iPr–CH3), 10.5 [NC(CH3)C(CH3)N], 47.1 (iPr–CH), 61.6
to afford 302 mg (609 μmol, yield: 70%) of a colorless powder. (NCN), 121.2 (NCCN). Ph6Sn2 (3): vide supra.
C21H26Cl2N2Sn [496.06 g·mol–1]: calcd. (found): C: 50.85 (51.18), H:
1
5.28 (5.34), N: 5.65 (5.18)%. H NMR (400.4 MHz, C6D6, 298 K): δ
Single Crystal X-ray Diffraction: Crystal data of 1 and 2 were col-
lected with a Bruker X8 Apex-II diffractometer with a CCD area detec-
3
3
= 1.32 (d, 12 H, JHH = 6.7 Hz, iPr–CH3), 4.90 (sept, 2 H, JHH
=
6.7 Hz, iPr–CH), 7.31 – 7.40 (m, 6 H, aryl-CH), 7.53 (s, 2 H, tor and graphite- or mirror-monochromated Mo-Kα radiation at 100 K.
NCHCHN), 8.48 – 8.53 (m,
H, aryl-CH). 13C{1H} NMR The structures were solved by intrinsic phasing method (SHELXT)
(100.7 MHz, C6D6, 298 K): δ = 22.6 (iPr-CH3), 53.3 (iPr-CH), 118.6 and refined with the SHELXL program.[16] All non-hydrogen atoms
4
(NCHCHN), 128.7, 130.0, 137.58 143.0 (aryl-C), 163.7 (NCN);
119Sn{1H} NMR (149.3 MHz, C6D6, 298 K): δ = –316.7 ppm.
were refined anisotropically and all hydrogen atoms were assigned to
idealized geometric positions.
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48, 798–800; d) V. Jancik, L. W. Pineda, J. Pinkas, H. W. Roesky,
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this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
numbers CCDC-1496678 (1) and CCDC-1496679 (2) (Fax: +44-1223-
336-033; E-Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.
uk).
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Crystal Data of (iPr2Im)·SnPh2Cl2 (1): C28H34N2Sn, Mr = 588.16,
colorless block, 0.29ϫ0.23ϫ0.20 mm, orthorhombic space group
P212121, a = 11.5079(6) Å, b = 13.7960(7) Å, c = 17.5383(9) Å, α =
β = γ = 90°, V = 2784.4(2) Å3, T = 100 K, Z = 4, ρcalcd. = 1.403 g·cm–3,
μ = 1.127 mm–1, F(000) = 1200, 36338 reflections in h(–14/14),
k(–17/17), l(–21/21) measured in the range 1.878° Ͻ θ Ͻ 26.073°,
completeness 99.9%, 5503 independent reflections, 5323 observed re-
flections [I Ͼ 2σ(I)], 304 parameters, 0 restraints; all data: R1 = 0.0169
and wR2 = 0.0419, I Ͼ 2σ(I): R1 = 0.0159 and wR2 = 0.0408, Goof
1.048, largest difference peak/hole 0.427/–0.205 e·Å–3.
Crystal Data of (iPr2Im)·SnMe2Cl2 (2): C11H22N2Sn, Mr = 371.89,
colorless block, 0.12ϫ0.05ϫ0.04 mm, monoclinic space group P21/
c, a = 6.5815(13) Å, b = 15.339(3) Å, c = 15.895(3) Å, β = 95.74(3)
α = γ = 90°, V = 1596.6(6) Å3, T = 100 K, Z = 4, ρcalcd. = 1.547 g·cm–3,
μ = 1.915 mm–1, F(000) = 744, 4493 reflections in h(–8/8), k(0/18),
l(0/19) measured in the range 1.849° Ͻ θ Ͻ 26.019°, completeness
99.9%, 4493 independent reflections, 4189 observed reflections [I Ͼ
2σ(I)], 152 parameters, 0 restraints; all data: R1 = 0.0399 and wR2 =
0.0767, I Ͼ 2σ(I): R1 = 0.0348 and wR2 = 0.0743, Goof 0.839, largest
difference peak/hole 0.680/–0.839 e·Å–3.
Acknowledgements
This work was supported by the Julius-Maximilians-Universität
Würzburg and the Deutsche Forschungsgemeinschaft (DFG, RA720/
13–1).
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Received: July 29, 2016
Published Online: ᭿
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Journal of Inorganic and General Chemistry
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ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
H. Schneider, M. J. Krahfuß, U. Radius* ......................... 1–6
To Rearrange or not to Rearrange: Reactivity of NHCs towards
Chloro- and Hydrostannanes R2SnCl2 (R = Me, Ph) and
Ph3SnH
Z. Anorg. Allg. Chem. 0000, 0–0
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